[Federal Register Volume 78, Number 36 (Friday, February 22, 2013)]
[Notices]
[Pages 12542-12584]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-03681]
[[Page 12541]]
Vol. 78
Friday,
No. 36
February 22, 2013
Part IV
Department of Commerce
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National Oceanic and Atmospheric Administration
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Takes of Marine Mammals Incidental to Specified Activities; Taking
Marine Mammals Incidental to an Exploration Drilling Program in the
Chukchi Sea, Alaska; Notice
Federal Register / Vol. 78, No. 36 / Friday, February 22, 2013 /
Notices
[[Page 12542]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XC494
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to an Exploration Drilling Program in
the Chukchi Sea, AK
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments.
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SUMMARY: NMFS received an application from ConocoPhillips Company (COP)
for an Incidental Harassment Authorization (IHA) to take marine
mammals, by harassment, incidental to offshore exploration drilling on
Outer Continental Shelf (OCS) leases in the Chukchi Sea, Alaska.
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting
comments on its proposal to issue an IHA to COP to take, by Level B
harassment only, 12 species of marine mammals during the specified
activity.
DATES: Comments and information must be received no later than March
25, 2013.
ADDRESSES: Comments on the application should be addressed to Michael
Payne, Chief, Permits and Conservation Division, Office of Protected
Resources, National Marine Fisheries Service, 1315 East-West Highway,
Silver Spring, MD 20910. The mailbox address for providing email
comments is [email protected]. NMFS is not responsible for email
comments sent to addresses other than the one provided here. Comments
sent via email, including all attachments, must not exceed a 25-
megabyte file size.
Instructions: All comments received are a part of the public record
and will generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information
(for example, name, address, etc.) voluntarily submitted by the
commenter may be publicly accessible. Do not submit Confidential
Business Information or otherwise sensitive or protected information.
A copy of the application, which contains several attachments,
including COP's marine mammal mitigation and monitoring plan and Plan
of Cooperation, used in this document may be obtained by writing to the
address specified above, telephoning the contact listed below (see FOR
FURTHER INFORMATION CONTACT), or visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm. Documents cited in this
notice may also be viewed, by appointment, during regular business
hours, at the aforementioned address.
FOR FURTHER INFORMATION CONTACT: Candace Nachman, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
direct the Secretary of Commerce to allow, upon request, the
incidental, but not intentional, taking of small numbers of marine
mammals by U.S. citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and either regulations are issued or, if the taking
is limited to harassment, a notice of a proposed authorization is
provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s), will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses (where
relevant), and if the permissible methods of taking and requirements
pertaining to the mitigation, monitoring and reporting of such takings
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103
as ``* * *an impact resulting from the specified activity that cannot
be reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.''
Section 101(a)(5)(D) of the MMPA established an expedited process
by which citizens of the U.S. can apply for an authorization to
incidentally take small numbers of marine mammals by harassment.
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of
an application followed by a 30-day public notice and comment period on
any proposed authorizations for the incidental harassment of marine
mammals. Within 45 days of the close of the comment period, NMFS must
either issue or deny the authorization.
Except with respect to certain activities not pertinent here, the
MMPA defines ``harassment'' as:
any act of pursuit, torment, or annoyance which (i) has the
potential to injure a marine mammal or marine mammal stock in the
wild [``Level A harassment'']; or (ii) has the potential to disturb
a marine mammal or marine mammal stock in the wild by causing
disruption of behavioral patterns, including, but not limited to,
migration, breathing, nursing, breeding, feeding, or sheltering
[``Level B harassment''].
Summary of Request
NMFS received an application on March 1, 2012, from COP for the
taking, by harassment, of marine mammals incidental to offshore
exploration drilling on OCS leases in the Chukchi Sea, Alaska. However,
before NMFS had an opportunity to review and comment on the March 1,
2012, submission, COP notified NMFS that they were making changes to
the request and submitted a new application on July 16, 2012. NMFS
reviewed COP's application and identified a number of issues requiring
further clarification. After addressing comments from NMFS, COP
modified its application and submitted a final revised application on
December 6, 2012. NMFS carefully evaluated COP's application, including
their analyses, and determined that the application was complete. The
December 6, 2012, submission (2nd application revision) is the one
available for public comment (see ADDRESSES) and considered by NMFS for
this proposed IHA.
COP plans to drill up to two exploration wells on OCS leases
offshore in the Chukchi Sea, Alaska, at the Devils Paw prospect during
the 2014 Arctic open-water season (July through October). Impacts to
marine mammals may occur from noise produced by the drill rig and
support vessels alongside the drill rig in dynamic positioning (DP)
mode, vertical seismic profile (VSP) surveys, and supporting vessels
(including icebreakers) and aircraft. COP has requested an
authorization to take 12 marine mammal species by Level B harassment,
and NMFS is proposing to authorize take incidental to COP's offshore
exploration drilling in the Chukchi Sea of the following species:
beluga whale (Delphinapterus leucas); bowhead whale (Balaena
mysticetus); gray whale (Eschrichtius robustus); killer whale (Orcinus
orca); minke whale (Balaenoptera acutorostrata); fin whale
(Balaenoptera physalus); humpback whale (Megaptera novaeangliae);
harbor porpoise (Phocoena phocoena); bearded seal (Erignathus
barbatus); ringed seal (Phoca hispida); spotted seal (P. largha); and
ribbon seal (Histriophoca fasciata).
Description of the Specified Activity and Specified Geographic Region
COP plans to conduct an offshore exploration drilling program on
U.S.
[[Page 12543]]
Department of the Interior (DOI), Bureau of Ocean Energy Management
(BOEM) Alaska OCS leases located greater than 70 mi (113 km) from the
Chukchi Sea coast during the 2014 open-water season. During the 2014
drilling program, COP plans to drill up to two exploration wells at the
prospect known as Devils Paw. See Figure 1 in COP's application for the
lease block and drill site locations (see ADDRESSES). The purpose of
COP's program is to test whether oil deposits are present in a
commercially viable quantity and quality. COP has stated that only if a
significant accumulation of hydrocarbons is discovered will the company
consider proceeding with development and production of the field.
Exploration Drilling
All of the possible Chukchi Sea offshore drill sites are located
approximately 120 mi (193 km) west of Wainwright, the community
proposed to be used for permanent infrastructure support for the
project. Approximate distances from the exploration drilling project
area to other communities along the Chukchi coast are 200 mi (322 km)
from Barrow, 90 mi (145 km) from Point Lay, and 175 mi (282 km) from
Point Hope. Water depths at the potential drill sites range from 132-
138 ft (40.2-42 m). Table 2 in COP's application provides the
coordinates for the potential drill sites (see ADDRESSES).
(1) Drill Rig Mobilization and Positioning
COP proposes to use a jack-up rig, instead of a drillship, to
conduct the proposed program. Generally, jack-up rigs consist of a
buoyant steel hull with three or more legs on which the hull can be
``jacked'' up or down. The jack-up drill rig has no self-propulsion
capability and therefore needs to be transported by a heavy-lift vessel
(HLV) from its original location to an area in the Bering Sea where it
would then be placed in a floating mode under the control of three
towing vessels. After delivering the jack-up rig, the HLV would depart
immediately via the Bering Strait and would not return until completion
of the project. When weather and ice conditions at the Devils Paw
Prospect are favorable, the support vessels will tow the rig into
position over the DP-5 drill site and initiate offloading.
Offloading procedures are estimated to take from 24 to 36 hrs,
dependent on weather. Initial drill rig placement and orientation would
be determined by logistics, current and forecasted weather events, ice
extent, ice type, underwriter requirements, and safety considerations.
Actual positioning of the rig would be determined by the well design,
geology, shallow hazards, and seabed conditions. The rig would then be
jacked up, manned with a crew, and provisioned for commencing drilling.
The horizontal dimensions of the rig will be approximately 230 x 225 ft
(70 x 68 m). When operating, the hull will be about 40 ft (12 m) above
seawater surface. Maximum dimension of one leg spud can, which is the
part on the seafloor, is about 60 ft (18 m).
If weather and ice conditions at the Devils Paw Prospect area are
initially unfavorable, the HLV would transport the jack-up rig to the
alternate staging area located about 20 mi (32 km) south of Kivalina
and 6 mi (9.7 km) offshore (see Figure 1 in COP's application), offload
the rig, and depart the Chukchi Sea via the Bering Strait. This
alternative location has been chosen based on its proximity to
infrastructure and likelihood to be ice free at the time of transfer.
It may take up to 3 days to reach the prospect location from the
alternate staging area (approximately 190 mi away [306 km]).
If the rig is offloaded at the alternate staging area, it would be
placed into standby mode, which means it would be temporarily jacked up
and manned by a limited crew to wait for conditions to improve at the
prospect. In addition, support helicopters would be mobilized to Red
Dog Mine near Kotzebue as necessary. Once ice conditions and weather at
the Devils Paw Prospect area turn favorable, the anchor handling supply
tug (AHST) and other vessels standing by in the immediate vicinity of
the rig would move the rig to the prospect area. The rig would then be
jacked up, manned with a crew, and supplied to commence drilling. (2)
Support Vessel and Aircraft Movements
Various vessels will be involved in the drilling project, as
summarized in Table 1 of COP's application (see ADDRESSES). The vessels
involved in supporting the drilling operations will remain at about 5.5
mi (9 km) distance from the drill rig when they are not actively
supporting the drilling operations. Several vessels will also be
available for oil spill response purposes (see Table 1 in COP's
application). Most of these vessels are relatively small and will be
located aboard a mother vessel, either the oil spill response barge or
the landing craft. These vessels will not be deployed in the water,
unless needed to respond to a spill or to conduct oil spill response
exercises as directed by DOI's Bureau of Safety and Environmental
Enforcement (BSEE). The oil spill response vessel (OSRV) will also be
on standby at 5.5 mi (9 km) from the drill rig. In addition to the
vessels required for the actual drilling operations, a science vessel
will be conducting monitoring activities. Figure 3 in COP's application
provides an overview of the approximate locations of the vessels
relative to the rig. The vessels will be located upwind from the rig,
and, as such, they could be moved to any quadrant (A, B, C, or D)
denoted in the figure, depending on the prevailing wind and currents.
COP also intends to have two helicopters and one fixed-wing
airplane available as part of the operations. Helicopters would be used
for personnel and equipment transport between shore and the drill rig
consistently during operations. The airplane would be used for
personnel and equipment transport between onshore locations. Wainwright
would be the principal port from which crew transfers would take place;
however, it is possible that under certain circumstances these
activities might need to be conducted through Barrow or another
location.
(3) Drill Rig Resupply
Transport of supplies to and from the drill rig will primarily be
done with the ware vessel and offshore supply vessels (OSVs), although
any other project vessel with the capability of DP could be used. The
supplies would be loaded in Wainwright onto the large landing craft
from where they would be transferred to the supply vessels. This
transfer of supplies will take place somewhere between 5.5 mi (9 km) of
the drill rig and 5 mi (8 km) offshore of Wainwright. When not engaged
in transfers of supplies, the ware vessel and OSVs will be located
about 5.5 mi (9 km) from the drill rig. The large landing craft will be
located somewhere between 5.5 mi (9 km) of the drill site and 5 mi (8
km) offshore of Wainwright.
The duration of each supply trip by the ware vessel and OSV is
estimated to be up to 7 hrs, assuming the vessels depart from their
standby location at about 5.5 mi (9 km) of the rig. It would take
approximately 0.5 hr to travel one-way to the drill rig (cruising
mode). The supply vessel would be dynamically positioned next to the
rig for about 6 hrs for each transfer of fuel and less than 6 hrs for
each transfer of other supplies. The transit time between the large
landing craft and the supply vessels is about 3 hrs one-way.
The ware vessel is estimated to make about two to three trips per
week to the rig but could make an average of almost four resupply trips
per week over 14 weeks. Based on an estimated 53 trips per season and a
maximum of 6 hrs for
[[Page 12544]]
supply transfer, the ware vessel would be in DP mode up to a total of
318 hrs over the drilling season. The OSVs are estimated to make four
and a half resupply trips per week over 14 weeks. Based on an estimated
total of 63 trips, unloading supplies from the OSV to the rig would
take up to a total of 378 hrs (in DP mode) over the course of the
drilling season. Assuming that at any time only one supply vessel will
be in DP alongside the drill rig, the total duration of DP is 696 hrs.
(4) Personnel Transfer and Refueling
About 300 persons are estimated to be involved in the proposed
exploration drilling overall. The jack-up drill rig, support and oil
spill response vessels will be self-contained, and the crew will live
aboard the rig and vessels. Air support will be necessary to meet
personnel and supply needs once the rig is operational. The helicopter
will fly a direct route between Wainwright and the drill rig, eight to
ten times per week.
Three refueling events per well are expected to be required for the
drill rig, depending on the circumstances. The duration of a rig-
fueling event will be approximately 6 hrs. All refueling operations
will follow procedures approved by the U.S. Coast Guard.
Vertical Seismic Profile Test
COP intends to conduct two or three VSP data acquisition runs
inside the wellbore to obtain high-resolution seismic images with
detailed time-depth relationships and velocity profiles of the various
geological layers. The VSP data can be used to help reprocess existing
2D or 3D seismic data prior to drilling a potential future appraisal
well in case oil or gas is discovered during the proposed exploration
drilling.
The procedure of one VSP data acquisition run can be summarized as
follows (Figure 2 in COP's application provides a schematic of the
layout):
The source of energy for the VSP data acquisition,
typically consisting of one or more airguns, will be lowered from the
drilling platform or a vessel to a depth of approximately 10 ft (3 m)
to 30 ft (10 m) below the water surface (depending on sea state). The
total volume of the airgun(s) is not expected to exceed 760 in\3\.
A minimum of two geophones positioned 50 ft (15.2 m) apart
will be placed at the end of a wireline cable, which will be lowered
into the wellbore to total depth. Once total depth has been reached,
the wireline cable will be pulled up and stopped at predefined depths
(geophone stations). Data will be acquired by producing a series of
sound pulses from the airgun(s) over a period of approximately 1 min.
The sound waves generated by the source and reflected from various
geological layers will be recorded by the two geophones.
After each 1-minute airgun activity, the wireline cable
with the geophones will be pulled up to a shallower position in the
well after which the airgun(s) will again produce a series of sound
pulses over a period of approximately 1 min. This process will be
repeated until data have been acquired at all pre-identified geophone
stations.
Two or three VSP data acquisition runs will be conducted; the first
run will take place upon reaching the bottom of the 17.5-in (44.5 cm)
borehole at approximately 5,220 ft (1,590 m) below sea level (bsl), the
second run upon reaching the bottom of the 13.5 and 8.5 in (34.2 and
21.5 cm) borehole at approximately 9,580 ft (2,920 m) bsl, and a
possible third run upon reaching the bottom of the 6.5 in (16.5 cm)
borehole at approximately 11,020 ft (33,590 m) bsl. If the integrity of
the 8.5 in borehole allows drilling to 11,020 ft without the need for
an extra casing a third VSP run might not be needed. The number of
geophone stations for each of the three VSP data acquisition runs
varies depending on the length of the wellbore to be surveyed. The time
required to finish a VSP data acquisition run depends on the depth of
the wellbore (resulting in longer time to lower and pull up the wire
cable with geophones) and the number of stations (resulting in longer
data acquisition time). The period between VSP data acquisition runs is
about 7-10 days, depending on the drilling progress. The total amount
of time that airguns are operating for the three runs combined that
might be performed in a well is about 2 hrs, not including ramp up. In
case a second well is drilled, two or three additional VSP data
acquisition runs might be conducted, meaning an additional 2 hrs of
airgun operations over the course of the entire open-water drilling
season.
Ice Management
Understanding ice systems and monitoring their movement are
important aspects of COP's Chukchi Sea operations. COP has monitored
Chukchi Sea ice since 2008 and would continue that monitoring through
the proposed drilling season. Initial monitoring would incorporate
satellite imagery to observe the early stages of sea ice retreat. Upon
arrival in the project area, the ice management vessel, possibly with
one other project vessel, would operate at the edge of the ice pack and
monitor ice activity, updating all interested parties on ice pack
coordinates to help determine scheduling for mobilization of the rig.
COP has submitted an Ice Alerts Plan to BOEM for approval in connection
with the Exploration Plan. The Ice Alerts Plan summarizes historic ice
monitoring results which has assisted COP in estimating the timing and
placement of the rig and support vessels. Under the COP Ice Alerts
Plan, an ice monitoring and management center based out of Anchorage
will monitor and interpret information collected from project vessels
and satellite imagery during the entire drilling operation. A summary
of the major components of COP's Ice Alerts Plan is provided below.
The ice edge position will be tracked in near real time using
observations from satellite images, from the ice management vessel or
other project vessels. The ice management and project vessels used for
ice observations will remain on standby within about 5.5 mi (9 km) of
the drill rig, unless deployed to investigate migrating ice-floes. When
investigating ice, the vessels will likely stay within about 75 mi (121
km) of the rig. The Ice Alerts Plan includes a process for determining
how close hazardous ice can approach before the well needs to be
secured and the jack-up rig moved. This critical distance is a function
of rig operations at that time, the speed and direction of the ice, the
weather forecast, and the method of ice management.
Based on available historical and more recent ice data, there is
low probability of ice entering the drilling area during the open water
season. However, if hazardous ice is on a trajectory to approach the
rig, the ice management vessel will be available to respond. One option
for responding is to use the vessels fire monitor (water cannon) to
modify the trajectory of the floe. Another option is to redirect the
ice by applying pressure with the bow of the ice management vessel,
slowly pushing the ice away from the direction of the drill rig. At
these slow speeds, the vessel would use low power and slow propeller
rotation speed, thereby reducing noise generation from propeller
rotation effects in the water. Icebreaking is not planned as a way to
manage ice that may be on a trajectory toward the drilling rig. In case
the jack-up rig needs to be moved due to approaching ice, the support
vessels will tow the rig to a secure location.
Timeframe of Activities
COP's anticipated start and end dates of the mobilization, drilling
operations, and demobilization are on or about June 15, 2014, and
November 16, 2014,
[[Page 12545]]
respectively, with actual activities in the lease sale area taking
place roughly from July through October. Vessels would not arrive at
the prospect prior to July 1. The HLV with the jack-up drill rig is
expected to originate from Southeast Asia or the North Sea. The HLV
will depart the area as soon as it has offloaded the rig. The AHST,
OSVs, and ware vessel will mobilize from the Gulf of Mexico in early
June and will be traveling north in close proximity to the HLV and
jack-up rig. The ice management vessel will be the first to mobilize to
the drill site to provide information on ice conditions to the HLV and
other vessels.
COP anticipates the drilling of one well will take approximately 40
days. After the first Devils Paw well is drilled, it will be plugged
and abandoned. If there is enough time, as estimated by the ice
monitoring system, COP intends to drill a second well, which could take
another 40 days. Relocation of the rig from the first to the second
well would take approximately 24-48 hrs. If a second well is drilled,
it would also be plugged and abandoned.
When drilling is completed, the jack-up rig will be demobilized and
excess material transferred from the rig to supply vessels. The rig
will then be jacked down and taken under tow by the AHST and OSVs to
the load-out site, anticipated to be located south of the Devils Paw
prospect area. The rig will remain in tow by the AHST until the HLV
arrives. In case the drilling season ends earlier than anticipated, the
rig may be towed to the alternate staging area and jacked up until the
HLV arrives. In that situation, helicopters will be mobilized to Nome
or the Red Dog Mine to support the rig as necessary. Once the AHST has
the jack-up rig under tow, all other support vessels would be
dismissed. The AHST and OSVs would accompany the rig until it is loaded
onto the HLV. Once the rig has been loaded onto the HLV, the AHST,
supply vessels, and air support will be demobilized.
Exploratory Drilling Program Sound Characteristics
Potential impacts to marine mammals could occur from the noise
produced by the jack-up rig and its support vessels (including the ice
management vessels and during DP), aircraft, and the airgun array
during VSP tests. The drill rig produces continuous noise into the
marine environment. NMFS currently uses a threshold of 120 dB re 1
[mu]Pa (rms) for the onset of Level B harassment from continuous sound
sources. This 120 dB threshold is also applicable for the support
vessels during DP. The airgun array proposed to be used by COP for the
VSP tests produces pulsed noise into the marine environment. NMFS
currently uses a threshold of 160 dB re 1 [mu]Pa (rms) for the onset of
Level B harassment from pulsed sound sources.
(1) Drill Rig Sounds
The main contributors to the underwater sound levels from jack-up
rig drilling activities are the use of generators and drilling
machinery. Few underwater noise measurements exist from operations
using a drill rig. Here we summarize the results from the drilling rig
Ocean General and its two support vessels in the Timor Sea, Northern
Australia (McCauley, 1998) and the jack-up rig Spartan 151 in Cook
Inlet, Alaska (MAI, 2011). For comparison, COP also included
information on drilling sound measurements from a concrete drilling
island and drillship. However, the sound propagation of a jack-up rig
is substantially less than that of a drillship because the components
that generate sound from a jack-up rig sit above the surface of the
water instead of in the water.
McCauley (1998) conducted measurements under three different
conditions: (a) Drilling rig sounds without drilling; (b) actively
drilling, with the support vessel on anchor; and (c) drilling with the
support vessel loading the rig (McCauley, 1998). The primary noise
sources from the drill rig itself were from mechanical plants, fluid
discharges, pumping systems and miscellaneous banging of gear on the
rig. The overall noise level was low (117 dB re 1[mu]Pa at 410 ft [125
m]) mainly because the deck of the rig was well above the waterline
(which is also the case for jack-up rigs). When the rig was actively
drilling, the drill rig noise dominated the drilling sounds to a
distance of about 1,312 ft (400 m). Beyond that distance, the energy
from the drill string tones (in the 31 and 62 Hz \1/3\ octaves) became
apparent and resulted in an increase in the overall received noise
level. With the rig drilling, the highest noise levels encountered were
on the order of 117 dB re 1[mu]Pa at 410 ft (125 m) and 115 dB
re1[mu]Pa at 1,228 ft (405 m). The noise source that far exceeded the
previous two was from the support vessel standing alongside the rig for
loading purposes. The thrusters and main propellers were engaged to
keep the vessel in position and produced high levels of cavitation
sound. The sound was broadband in nature, with highest levels of 137 dB
1[mu]Pa at 1,328 ft (405 m) and levels of 120 dB re 1[mu]Pa at 1.8-2.4
mi (3-4 km) from the well head.
Acoustic measurements of the drilling rig Spartan 151 were
conducted to report on underwater sound characteristics as a function
of range using two different systems (moored hydrophone and real time
system). Both systems provided consistent results. Primary sources of
rig-based underwater sounds were from the diesel engines, mud pump,
ventilation fans (and associated exhaust), and electrical generators.
The loudest source levels (from the diesel engines) were estimated at
137 dB re 1 [mu]Pa at 1 m (rms) in the 141-178 Hz \1/3\ octave band.
Based on this estimate, the 120 dB (rms) re 1 [mu]Pa sound pressure
level would be at about 154 ft (50 m) away from where the energy enters
the water (jack-up leg or drill riser).
Hall and Francine (1991) measured drilling sounds from an offshore
concrete island drilling structure. Source sound pressure level was 131
dB re 1[mu]Pa at 1 m for the drilling structure at idle (no drilling),
and a transmission loss rate of 2.6 dB per doubling of distance,
slightly less than theoretical cylindrical spreading. At a distance of
912 ft (278 m) from the drilling island the broadband sound pressure
level was 109 dB re 1[mu]Pa. Strong tonal components at 1.375-1.5 Hz
were detected in the acoustic records during drilling activities. These
were likely associated with the rotary turntable, which was rotating
between 75 and 110 rpm (which corresponds to 1.25-1.83 Hz). The
received broadband sound pressure level at 849 ft (259 m) was 124 dB re
1[mu]Pa. The sounds measured from the concrete drilling island were
almost entirely (>95%) composed of energy below 20 Hz.
Sound pressure levels of drilling activities from the concrete
drilling island were substantially less than those reported for drill
ships (Greene, 1987a). At a range of 557 ft (170 m) the 20-1000 Hz band
level was 122-125 dB for the drillship Explorer I, with most energy
below 600 Hz (although tones up to 1850 Hz were recorded). Drilling
activity from the Explorer was measured as 134 dB at a range of 656 ft
(200 m), with all energy below 600 Hz. Underwater sound measurements
from the drillship Kulluk at 3,215 ft (980 m) were substantially higher
(143 dB re 1[mu]Pa). Underwater sound levels recorded from the
drillship Stena Forth in Disko Bay, Greenland, corresponded to
measurements from other drillships and were higher than sound levels
reported for semi-submersibles and drill rigs (Kyhn et al., 2011). The
broadband source levels were similar to a fast
[[Page 12546]]
moving merchant vessel with source levels up to 184-190 dB re 1 [mu]Pa
during drilling and maintenance work, respectively. At a range of 1,640
ft (500 m) from the drillship the 10-1000 Hz band level during drilling
at 295 ft (90 m) ranged from approximately 100-128 dB re1 [mu]Pa, with
the highest sound level at 100 and 400 Hz. Sound levels were <=110 dB
re1 [mu]Pa at 1.2 mi (2 km) distance.
Expected sound pressure levels for the proposed drilling activities
have been modeled by JASCO Applied Research, Inc. for drilling sounds
only and for drilling sounds in combination with the proximity of a
support vessel using DP. The acoustic modeling results show that the
maximum radii to received sound levels of 120 and 160 dB re 1 [mu]Pa
from drilling operations alone are 689 ft (210 m) and <33 ft (10 m),
respectively (O'Neill et al., 2012). More detailed results are included
in Attachment A of COP's IHA application.
(2) Vessel Sounds
In addition to the drill rig, various types of vessels will be used
in support of the operations including ice management vessels, anchor
handlers, supply vessels and oil-spill response vessels. Like other
industry-generated sound, underwater sound from vessels is generally
most apparent at relatively low frequencies (20-500 Hz). The sound
characteristic of each vessel is unique depending upon propulsion unit,
machinery, hull size and shape. These characteristics change with load,
vessel speed and weather conditions. For example, increase in vessel
size, power and speed produces increasing broadband and tonal noise.
The sound produced by vessels is generated by engine machinery and
propeller cavitation. When a vessel increases speed, broadband sound
from propeller cavitation and hull vibration becomes dominant over
machinery sound. It has been estimated that propeller cavitation
produces at least 90% of all ship generated ambient noise (Ross, 2005).
Sound from large vessels is generally higher at low frequencies. Small
high-powered (>100 horse power [HP]) propeller driven boats often
exceed large vessel sound at frequencies above 1 kHz.
Ice management vessels operating in thick ice require a greater
amount of power and propeller cavitation and hence produce higher sound
levels than ships of similar size during normal operation in open water
(Richardson et al., 1995b). Roth and Schmidt (2010) examined ice
management vessel sound pressure levels during different sea ice
conditions and modes of propulsion. Comparison of source spectra in
open-water and while breaking moderate ice showed increases as much as
15 dB between 20 Hz and 2 kHz. For low frequencies, a sound pressure
level of about 193 dB re 1[mu]Pa at 1 m was estimated to be a
reasonable peak value.
Numerous measurements of underwater vessel sound have been
performed since 2000 (for review see Wyatt, 2008) mostly in support of
industry activity. Results of underwater vessel sounds that have been
measured in the Chukchi and Beaufort Seas were reported in various 90-
day and comprehensive reports since 2007 (e.g., Aerts et al., 2008;
Hauser et al., 2008; Brueggeman et al., 2009a; Ireland et al., 2009).
Due to the highly variable conditions under which these measurements
were conducted, including equipment and methodology used, it is
difficult to compare source levels (i.e., back calculated sound levels
at a theoretical 1 m from the source) or even received levels between
vessels. For example, source sound pressure levels of the same tug with
barge varied from 173 dB to 182 dB re 1[mu]Pa at 1 m, depending on the
speed and load at the time of measurement (Zykov and Hannay, 2006).
Sound pressure levels of a drill rig support vessel traveling at a
speed of about 11 knots (20 kph) was measured to be 136 dB re 1[mu]Pa
at 1,312 ft (400 m) (McCauley, 1998). Acoustic measurements of an
anchor handling support tug of similar size and horsepower traveling at
4.3 knots (8 kph) resulted in sound pressure levels of approximately
137 dB re 1[mu]Pa at 1,312 ft (400 m) and 120 dB re 1[mu]Pa at 4,855 ft
(1,480 m) (Funk et al., 2008).
(3) Aircraft Sounds
Helicopters are proposed to be used for personnel and equipment
transport to and from the drill rig. Over calm water away from shore,
the maximum transmission of rotor and engine sounds from helicopters
into the water can generally be visualized as a 26[deg] cone under the
aircraft. The size of the water surface area where transmission of
sound can take place is therefore generally larger with a higher flight
altitude, though the sound levels will be much lower due to the larger
distance from the water. In practice, the width of the area where
aircraft sounds will be received is usually wider than the 26[deg] cone
and varies with sea state because waves provide suitable angles for
additional transmission of the sound. In shallow water, scattering and
absorption will limit lateral propagation. Dominant tones in noise
spectra from helicopters are generally below 500 Hz (Greene and Moore,
1995). Harmonics of the main rotor and tail rotor usually dominate the
sound from helicopters; however, many additional tones associated with
the engines and other rotating parts are sometimes present. Because of
Doppler shift effects, the frequencies of tones received at a
stationary site diminish when an aircraft passes overhead. The apparent
frequency is increased while the aircraft approaches and is reduced
while it moves away. Aircraft flyovers are not heard underwater for
very long, especially when compared to how long they are heard in air
as the aircraft approaches an observer.
Underwater sounds were measured for a Bell 212 helicopter (Greene
1982, 1985; Richardson et al., 1990). These measurements show that
there are numerous prominent tones at frequencies up to about 350 Hz,
with the strongest measured tone at 20-22 Hz. Received peak sound
levels of a Bell 212 passing over a hydrophone at an altitude of
approximately 1,000 ft (300 m), varied between 106-111 dB re 1[mu]Pa at
29 and 59 ft (9 and 18 m) water depth. Two Class 1 or Group A type
helicopters will fly to and from the jack-up rig for transportation of
manpower and supplies. Helicopters will be operated by a flight crew of
two and capable of carrying 12 to 13 passengers.
(4) Vertical Seismic Profile Airgun Sounds
Airguns function by venting high-pressure air into the water. The
pressure signature of an individual airgun consists of a sharp rise and
then fall in pressure, followed by several positive and negative
pressure excursions caused by oscillation of the resulting air bubble.
Most energy emitted from airguns is at relatively low frequencies.
Typical high-energy airgun arrays emit most energy at 10-120 Hz.
However, the pulses contain significant energy up to 500-1000 Hz and
some energy at higher frequencies (Goold and Fish, 1998; Potter et al.,
2007). Studies in the Gulf of Mexico have shown that the horizontally-
propagating sound can contain significant energy above the frequencies
that airgun arrays are designed to emit (DeRuiter et al., 2006; Madsen
et al., 2006; Tyack et al., 2006). Energy at frequencies up to 150 kHz
was found in tests of single 60-in\3\ and 250-in\3\ airguns (Goold and
Coates, 2006). Nonetheless, the predominant energy is at low
frequencies.
The strengths of airgun pulses can be measured in different ways,
and it is important to know which method is being used when
interpreting quoted source or received levels. Geophysicists usually
quote peak-to-peak (p-p) levels, in bar-meters or (less often) dB re 1
[mu]Pa.
[[Page 12547]]
Peak level (zero-to-peak [0-p]) for the same pulse is typically
approximately 6 dB less. In the biological literature, levels of
received airgun pulses are often described based on the average or rms
level, where the average is calculated over the duration of the pulse.
The rms value for a given airgun pulse is typically approximately 10 dB
lower than the peak level and 16 dB lower than the p-p value (Greene,
1997; McCauley et al., 1998, 2000). A fourth measure that is
increasingly used is the Sound Exposure Level (SEL), in dB re 1
[mu]Pa2s. Because the pulses, even when stretched by propagation
effects (see below), are usually <1 s in duration, the numerical value
of the energy is usually lower than the rms pressure level. However,
the units are different.
Because the level of a given pulse will differ substantially
depending on which of these measures is being applied, it is important
to be aware which measure is in use when interpreting any quoted pulse
level. NMFS refers to rms levels when discussing levels of pulsed
sounds that may harass marine mammals; these are the units used in this
IHA notice. Specifics about the VSP airgun(s) and expected radii of
various received rms sound levels are included in the acoustic modeling
report of JASCO Applied Sciences (Attachment A of COP's application).
The airgun array proposed for use will not exceed 760 in\3\. The VSP
airgun operations differ from normal marine seismic surveys in that the
airguns are fixed to one location (the drill rig), and a limited number
of shots will be fired (a total of about 2 hrs of airgun activity per
well, not including time required for ramp ups).
Although there will be several support vessels in the drilling
operations area, NMFS considers the possibility of collisions with
marine mammals highly unlikely. Once on location, the majority of the
support vessels will remain in the area of the drill rig throughout the
2014 drilling season and will not be making trips between the shorebase
and the offshore vessels (with the exception of the resupply transits).
As noted earlier in this document and in Figure 3 of COP's application,
the majority of the vessels will sit on standby mode approximately 5.5
mi (9 km) upwind of the drill rig. As the crew change/resupply
activities are considered part of normal vessel traffic and are not
anticipated to impact marine mammals in a manner that would rise to the
level of taking, those activities are not considered further in this
document.
Description of Marine Mammals in the Area of the Specified Activity
The Chukchi Sea supports a diverse assemblage of marine mammals,
including: bowhead, gray, beluga, killer, minke, humpback, and fin
whales; harbor porpoise; ringed, ribbon, spotted, and bearded seals;
narwhals (Monodon monoceros); polar bears (Ursus maritimus); and
walruses (Odobenus rosmarus divergens; see Table 3 in COP's
application). The bowhead, humpback, and fin whales are listed as
``endangered'' under the Endangered Species Act (ESA) and as depleted
under the MMPA. The ringed and bearded seals are listed as
``threatened'' under the ESA. Certain stocks or populations of gray,
beluga, and killer whales and spotted seals are listed as endangered or
are proposed for listing under the ESA; however, none of those stocks
or populations occur in the proposed activity area. Additionally, the
ribbon seal is considered a ``species of concern'' under the ESA. Both
the walrus and the polar bear are managed by the U.S. Fish and Wildlife
Service (USFWS) and are not considered further in this proposed IHA
notice.
Of these species, 12 are expected to occur in the area of COP's
proposed operations. These species include: the bowhead, gray,
humpback, minke, fin, killer, and beluga whales; harbor porpoise; and
the ringed, spotted, bearded, and ribbon seals. Beluga, bowhead, gray,
and killer whales, harbor porpoise, and ringed, bearded, and spotted
seals are anticipated to be encountered more than the other four marine
mammal species mentioned here. The marine mammal species that is likely
to be encountered most widely (in space and time) throughout the period
of the proposed drilling program is the ringed seal. Encounters with
bowhead and gray whales are expected to be limited to particular
seasons. Where available, COP used density estimates from peer-reviewed
literature in the application. In cases where density estimates were
not readily available in the peer-reviewed literature, COP used other
methods to derive the estimates. NMFS reviewed the density estimate
descriptions and documents and determined that they were acceptable for
these purposes. The explanation for those derivations and the actual
density estimates are described later in this document (see the
``Estimated Take by Incidental Harassment'' section).
The narwhal occurs in Canadian waters and occasionally in the
Alaskan Beaufort Sea and the Chukchi Sea, but it is considered
extralimital in U.S. waters and is not expected to be encountered.
There are scattered records of narwhal in Alaskan waters, including
reports by subsistence hunters, where the species is considered
extralimital (Reeves et al., 2002). Due to the rarity of this species
in the proposed project area and the remote chance it would be affected
by COP's proposed Chukchi Sea drilling activities, this species is not
discussed further in this proposed IHA notice.
COP's application contains information on the status, distribution,
seasonal distribution, abundance, and life history of each of the
species under NMFS jurisdiction mentioned in this document. When
reviewing the application, NMFS determined that the species
descriptions provided by COP correctly characterized the status,
distribution, seasonal distribution, and abundance of each species.
Please refer to the application for that information (see ADDRESSES).
Additional information can also be found in the NMFS Stock Assessment
Reports (SAR). The Alaska 2011 SAR is available at: http://www.nmfs.noaa.gov/pr/pdfs/sars/ak2011.pdf.
Brief Background on Marine Mammal Hearing
When considering the influence of various kinds of sound on the
marine environment, it is necessary to understand that different kinds
of marine life are sensitive to different frequencies of sound. Based
on available behavioral data, audiograms have been derived using
auditory evoked potentials, anatomical modeling, and other data,
Southall et al. (2007) designate ``functional hearing groups'' for
marine mammals and estimate the lower and upper frequencies of
functional hearing of the groups. The functional groups and the
associated frequencies are indicated below (though animals are less
sensitive to sounds at the outer edge of their functional range and
most sensitive to sounds of frequencies within a smaller range
somewhere in the middle of their functional hearing range):
Low frequency cetaceans (13 species of mysticetes):
functional hearing is estimated to occur between approximately 7 Hz and
22 kHz (however, a study by Au et al. (2006) of humpback whale songs
indicate that the range may extend to at least 24 kHz);
Mid-frequency cetaceans (32 species of dolphins, six
species of larger toothed whales, and 19 species of beaked and
bottlenose whales): functional hearing is estimated to occur between
approximately 150 Hz and 160 kHz;
[[Page 12548]]
High frequency cetaceans (eight species of true porpoises,
six species of river dolphins, Kogia, the franciscana, and four species
of cephalorhynchids): functional hearing is estimated to occur between
approximately 200 Hz and 180 kHz; and
Pinnipeds in Water: functional hearing is estimated to
occur between approximately 75 Hz and 75 kHz, with the greatest
sensitivity between approximately 700 Hz and 20 kHz.
As mentioned previously in this document, 12 marine mammal species
(four pinniped and eight cetacean species) are likely to occur in the
proposed drilling area. Of the eight cetacean species likely to occur
in COP's project area, five are classified as low frequency cetaceans
(i.e., bowhead, gray, humpback, minke, and fin whales), two are
classified as mid-frequency cetaceans (i.e., beluga and killer whales),
and one is classified as a high-frequency cetacean (i.e., harbor
porpoise) (Southall et al., 2007).
Underwater audiograms have been obtained using behavioral methods
for four species of phocinid seals: the ringed, harbor, harp, and
northern elephant seals (reviewed in Richardson et al., 1995a; Kastak
and Schusterman, 1998). Below 30-50 kHz, the hearing threshold of
phocinids is essentially flat down to at least 1 kHz and ranges between
60 and 85 dB re 1 [mu]Pa. There are few published data on in-water
hearing sensitivity of phocid seals below 1 kHz. However, measurements
for one harbor seal indicated that, below 1 kHz, its thresholds
deteriorated gradually to 96 dB re 1 [mu]Pa at 100 Hz from 80 dB re 1
[mu]Pa at 800 Hz and from 67 dB re 1 [mu]Pa at 1,600 Hz (Kastak and
Schusterman, 1998). More recent data suggest that harbor seal hearing
at low frequencies may be more sensitive than that and that earlier
data were confounded by excessive background noise (Kastelein et al.,
2009a,b). If so, harbor seals have considerably better underwater
hearing sensitivity at low frequencies than do small odontocetes like
belugas (for which the threshold at 100 Hz is about 125 dB).
Pinniped call characteristics are relevant when assessing potential
masking effects of man-made sounds. In addition, for those species
whose hearing has not been tested, call characteristics are useful in
assessing the frequency range within which hearing is likely to be most
sensitive. The four species of seals present in the study area, all of
which are in the phocid seal group, are all most vocal during the
spring mating season and much less so during late summer. In each
species, the calls are at frequencies from several hundred to several
thousand hertz--above the frequency range of the dominant noise
components from most of the proposed oil exploration activities.
Cetacean hearing has been studied in relatively few species and
individuals. The auditory sensitivity of bowhead, gray, and other
baleen whales has not been measured, but relevant anatomical and
behavioral evidence is available. These whales appear to be specialized
for low frequency hearing, with some directional hearing ability
(reviewed in Richardson et al., 1995a; Ketten, 2000). Their optimum
hearing overlaps broadly with the low frequency range where exploration
drilling activities, airguns, and associated vessel traffic emit most
of their energy.
The beluga whale is one of the better-studied species in terms of
its hearing ability. As mentioned earlier, the auditory bandwidth in
mid-frequency odontocetes is believed to range from 150 Hz to 160 kHz
(Southall et al., 2007); however, belugas are most sensitive above 10
kHz. They have relatively poor sensitivity at the low frequencies
(reviewed in Richardson et al., 1995a) that dominate the sound from
industrial activities and associated vessels. Nonetheless, the noise
from strong low frequency sources is detectable by belugas many
kilometers away (Richardson and Wursig, 1997). Also, beluga hearing at
low frequencies in open-water conditions is apparently somewhat better
than in the captive situations where most hearing studies were
conducted (Ridgway and Carder, 1995; Au, 1997). If so, low frequency
sounds emanating from drilling activities may be detectable somewhat
farther away than previously estimated.
Call characteristics of cetaceans provide some limited information
on their hearing abilities, although the auditory range often extends
beyond the range of frequencies contained in the calls. Also,
understanding the frequencies at which different marine mammal species
communicate is relevant for the assessment of potential impacts from
manmade sounds. A summary of the call characteristics for bowhead,
gray, and beluga whales is provided next.
Most bowhead calls are tonal, frequency-modulated sounds at
frequencies of 50-400 Hz. These calls overlap broadly in frequency with
the underwater sounds emitted by many of the activities to be performed
during COP's proposed exploration drilling program (Richardson et al.,
1995a). Source levels are quite variable, with the stronger calls
having source levels up to about 180 dB re 1 [mu]Pa at 1 m. Gray whales
make a wide variety of calls at frequencies from <100-2,000 Hz (Moore
and Ljungblad, 1984; Dalheim, 1987).
Beluga calls include trills, whistles, clicks, bangs, chirps and
other sounds (Schevill and Lawrence, 1949; Ouellet, 1979; Sjare and
Smith, 1986a). Beluga whistles have dominant frequencies in the 2-6 kHz
range (Sjare and Smith, 1986a). This is above the frequency range of
most of the sound energy produced by the proposed exploratory drilling
activities and associated vessels. Other beluga call types reported by
Sjare and Smith (1986a,b) included sounds at mean frequencies ranging
upward from 1 kHz.
The beluga also has a very well developed high frequency
echolocation system, as reviewed by Au (1993). Echolocation signals
have peak frequencies from 40-120 kHz and broadband source levels of up
to 219 dB re 1 [mu]Pa-m (zero-peak). Echolocation calls are far above
the frequency range of the sounds produced by the devices proposed for
use during COP's Chukchi Sea exploratory drilling program. Therefore,
those industrial sounds are not expected to interfere with
echolocation.
Potential Effects of the Specified Activity on Marine Mammals
The likely or possible impacts of the proposed exploratory drilling
program in the Chukchi Sea on marine mammals could involve both non-
acoustic and acoustic effects. Potential non-acoustic effects could
result from the physical presence of the equipment and personnel.
Petroleum development and associated activities introduce sound into
the marine environment. Impacts to marine mammals are expected to
primarily be acoustic in nature. Potential acoustic effects on marine
mammals relate to sound produced by drilling activity, supply and
support vessels on DP, and aircraft, as well as the VSP airgun array.
The potential effects of sound from the proposed exploratory drilling
program might include one or more of the following: tolerance; masking
of natural sounds; behavioral disturbance; non-auditory physical
effects; and, at least in theory, temporary or permanent hearing
impairment (Richardson et al., 1995a). However, for reasons discussed
later in this document, it is unlikely that there would be any cases of
temporary, or especially permanent, hearing impairment resulting from
these activities. As outlined in previous NMFS documents, the effects
of noise on marine mammals are highly variable, and can be categorized
as follows (based on Richardson et al., 1995b):
[[Page 12549]]
(1) The noise may be too weak to be heard at the location of the
animal (i.e., lower than the prevailing ambient noise level, the
hearing threshold of the animal at relevant frequencies, or both);
(2) The noise may be audible but not strong enough to elicit any
overt behavioral response;
(3) The noise may elicit reactions of variable conspicuousness and
variable relevance to the wellbeing of the marine mammal; these can
range from temporary alert responses to active avoidance reactions such
as vacating an area at least until the noise event ceases but
potentially for longer periods of time;
(4) Upon repeated exposure, a marine mammal may exhibit diminishing
responsiveness (habituation), or disturbance effects may persist; the
latter is most likely with sounds that are highly variable in
characteristics, infrequent, and unpredictable in occurrence, and
associated with situations that a marine mammal perceives as a threat;
(5) Any anthropogenic noise that is strong enough to be heard has
the potential to reduce (mask) the ability of a marine mammal to hear
natural sounds at similar frequencies, including calls from
conspecifics, and underwater environmental sounds such as surf noise;
(6) If mammals remain in an area because it is important for
feeding, breeding, or some other biologically important purpose even
though there is chronic exposure to noise, it is possible that there
could be noise-induced physiological stress; this might in turn have
negative effects on the well-being or reproduction of the animals
involved; and
(7) Very strong sounds have the potential to cause a temporary or
permanent reduction in hearing sensitivity. In terrestrial mammals, and
presumably marine mammals, received sound levels must far exceed the
animal's hearing threshold for there to be any temporary threshold
shift (TTS) in its hearing ability. For transient sounds, the sound
level necessary to cause TTS is inversely related to the duration of
the sound. Received sound levels must be even higher for there to be
risk of permanent hearing impairment. In addition, intense acoustic or
explosive events may cause trauma to tissues associated with organs
vital for hearing, sound production, respiration and other functions.
This trauma may include minor to severe hemorrhage.
Potential Acoustic Effects From Exploratory Drilling Activities
(1) Tolerance
Numerous studies have shown that underwater sounds from industry
activities are often readily detectable by marine mammals in the water
at distances of many kilometers. Numerous studies have also shown that
marine mammals at distances more than a few kilometers away often show
no apparent response to industry activities of various types (Miller et
al., 2005; Bain and Williams, 2006). This is often true even in cases
when the sounds must be readily audible to the animals based on
measured received levels and the hearing sensitivity of that mammal
group. Although various baleen whales, toothed whales, and (less
frequently) pinnipeds have been shown to react behaviorally to
underwater sound such as airgun pulses or vessels under some
conditions, at other times mammals of all three types have shown no
overt reactions (e.g., Malme et al., 1986; Richardson et al., 1995;
Madsen and Mohl, 2000; Croll et al., 2001; Jacobs and Terhune, 2002;
Madsen et al., 2002; Miller et al., 2005). In general, pinnipeds and
small odontocetes seem to be more tolerant of exposure to some types of
underwater sound than are baleen whales. Richardson et al. (1995b)
found that vessel noise does not seem to strongly affect pinnipeds that
are already in the water. Richardson et al. (1995b) went on to explain
that seals on haul-outs sometimes respond strongly to the presence of
vessels and at other times appear to show considerable tolerance of
vessels, and Brueggeman et al. (1992, cited in Richardson et al.,
1995b) observed ringed seals hauled out on ice pans displaying short-
term escape reactions when a ship approached within 0.25-0.5 mi (0.4-
0.8 km).
(2) Masking
Masking is the obscuring of sounds of interest by other sounds,
often at similar frequencies. Marine mammals are highly dependent on
sound, and their ability to recognize sound signals amid other noise is
important in communication, predator and prey detection, and, in the
case of toothed whales, echolocation. Even in the absence of manmade
sounds, the sea is usually noisy. Background ambient noise often
interferes with or masks the ability of an animal to detect a sound
signal even when that signal is above its absolute hearing threshold.
Natural ambient noise includes contributions from wind, waves,
precipitation, other animals, and (at frequencies above 30 kHz) thermal
noise resulting from molecular agitation (Richardson et al., 1995b).
Background noise also can include sounds from human activities. Masking
of natural sounds can result when human activities produce high levels
of background noise. Conversely, if the background level of underwater
noise is high (e.g., on a day with strong wind and high waves), an
anthropogenic noise source will not be detectable as far away as would
be possible under quieter conditions and will itself be masked.
Although some degree of masking is inevitable when high levels of
manmade broadband sounds are introduced into the sea, marine mammals
have evolved systems and behavior that function to reduce the impacts
of masking. Structured signals, such as the echolocation click
sequences of small toothed whales, may be readily detected even in the
presence of strong background noise because their frequency content and
temporal features usually differ strongly from those of the background
noise (Au and Moore, 1988, 1990). The components of background noise
that are similar in frequency to the sound signal in question primarily
determine the degree of masking of that signal.
Redundancy and context can also facilitate detection of weak
signals. These phenomena may help marine mammals detect weak sounds in
the presence of natural or manmade noise. Most masking studies in
marine mammals present the test signal and the masking noise from the
same direction. The sound localization abilities of marine mammals
suggest that, if signal and noise come from different directions,
masking would not be as severe as the usual types of masking studies
might suggest (Richardson et al., 1995b). The dominant background noise
may be highly directional if it comes from a particular anthropogenic
source such as a ship or industrial site. Directional hearing may
significantly reduce the masking effects of these noises by improving
the effective signal-to-noise ratio. In the cases of high-frequency
hearing by the bottlenose dolphin, beluga whale, and killer whale,
empirical evidence confirms that masking depends strongly on the
relative directions of arrival of sound signals and the masking noise
(Penner et al., 1986; Dubrovskiy, 1990; Bain et al., 1993; Bain and
Dahlheim, 1994). Toothed whales, and probably other marine mammals as
well, have additional capabilities besides directional hearing that can
facilitate detection of sounds in the presence of background noise.
There is evidence
[[Page 12550]]
that some toothed whales can shift the dominant frequencies of their
echolocation signals from a frequency range with a lot of ambient noise
toward frequencies with less noise (Au et al., 1974, 1985; Moore and
Pawloski, 1990; Thomas and Turl, 1990; Romanenko and Kitain, 1992;
Lesage et al., 1999). A few marine mammal species are known to increase
the source levels or alter the frequency of their calls in the presence
of elevated sound levels (Dahlheim, 1987; Au, 1993; Lesage et al.,
1993, 1999; Terhune, 1999; Foote et al., 2004; Parks et al., 2007,
2009; Di Iorio and Clark, 2009; Holt et al., 2009).
These data demonstrating adaptations for reduced masking pertain
mainly to the very high frequency echolocation signals of toothed
whales. There is less information about the existence of corresponding
mechanisms at moderate or low frequencies or in other types of marine
mammals. For example, Zaitseva et al. (1980) found that, for the
bottlenose dolphin, the angular separation between a sound source and a
masking noise source had little effect on the degree of masking when
the sound frequency was 18 kHz, in contrast to the pronounced effect at
higher frequencies. Directional hearing has been demonstrated at
frequencies as low as 0.5-2 kHz in several marine mammals, including
killer whales (Richardson et al., 1995b). This ability may be useful in
reducing masking at these frequencies. In summary, high levels of noise
generated by anthropogenic activities may act to mask the detection of
weaker biologically important sounds by some marine mammals. This
masking may be more prominent for lower frequencies. For higher
frequencies, such as that used in echolocation by toothed whales,
several mechanisms are available that may allow them to reduce the
effects of such masking.
Masking effects of underwater sounds from COP's proposed activities
on marine mammal calls and other natural sounds are expected to be
limited. For example, beluga whales primarily use high-frequency sounds
to communicate and locate prey; therefore, masking by low-frequency
sounds associated with drilling activities is not expected to occur
(Gales, 1982, as cited in Shell, 2009). If the distance between
communicating whales does not exceed their distance from the drilling
activity, the likelihood of potential impacts from masking would be low
(Gales, 1982, as cited in Shell, 2009). At distances greater than 660-
1,300 ft (200-400 m), recorded sounds from drilling activities did not
affect behavior of beluga whales, even though the sound energy level
and frequency were such that it could be heard several kilometers away
(Richardson et al., 1995b). This exposure resulted in whales being
deflected from the sound energy and changing behavior. These minor
changes are not expected to affect the beluga whale population
(Richardson et al., 1991; Richard et al., 1998). Brewer et al. (1993)
observed belugas within 2.3 mi (3.7 km) of the drilling unit Kulluk
during drilling; however, the authors do not describe any behaviors
that may have been exhibited by those animals.
There is evidence of other marine mammal species continuing to call
in the presence of industrial activity. Annual acoustical monitoring
near BP's Northstar production facility during the fall bowhead
migration westward through the Beaufort Sea has recorded thousands of
calls each year (for examples, see Richardson et al., 2007; Aerts and
Richardson, 2008). Construction, maintenance, and operational
activities have been occurring from this facility since the late 1990s.
To compensate and reduce masking, some mysticetes may alter the
frequencies of their communication sounds (Richardson et al., 1995b;
Parks et al., 2007). Masking processes in baleen whales are not
amenable to laboratory study, and no direct measurements on hearing
sensitivity are available for these species. It is not currently
possible to determine with precision the potential consequences of
temporary or local background noise levels. However, Parks et al.
(2007) found that right whales (a species closely related to the
bowhead whale) altered their vocalizations, possibly in response to
background noise levels. For species that can hear over a relatively
broad frequency range, as is presumed to be the case for mysticetes, a
narrow band source may only cause partial masking. Richardson et al.
(1995b) note that a bowhead whale 12.4 mi (20 km) from a human sound
source, such as that produced during oil and gas industry activities,
might hear strong calls from other whales within approximately 12.4 mi
(20 km), and a whale 3.1 mi (5 km) from the source might hear strong
calls from whales within approximately 3.1 mi (5 km). Additionally,
masking is more likely to occur closer to a sound source, and distant
anthropogenic sound is less likely to mask short-distance acoustic
communication (Richardson et al., 1995b).
Although some masking by marine mammal species in the area may
occur, the extent of the masking interference will depend on the
spatial relationship of the animal and COP's activity. Almost all
energy in the sounds emitted by drilling and other operational
activities is at low frequencies, predominantly below 250 Hz with
another peak centered around 1,000 Hz. Most energy in the sounds from
the vessels and aircraft to be used during this project is below 1 kHz
(Moore et al., 1984; Greene and Moore, 1995; Blackwell et al., 2004b;
Blackwell and Greene, 2006). These frequencies are mainly used by
mysticetes but not by odontocetes. Therefore, masking effects would
potentially be more pronounced in the bowhead and gray whales that
might occur in the proposed project area. If, as described later in
this document, certain species avoid the proposed drilling locations,
impacts from masking are anticipated to be low. Moreover, the very
small radius of the 120 dB isopleth of the drill rig (670 ft [210 m])
will reduce the possibility of masking even further. The larger 120 dB
isopleth of the drill rig while a support vessel is in DP mode beside
it (5 mi [8 km]) and over the VSP airguns (3 mi [5 km]) are also not
anticipated to result in substantial or long-term masking effects as
these activities will only occur for a short time during the entire
open-water season (696 hrs and 2-4 hrs total, respectively).
(3) Behavioral Disturbance Reactions
Behavioral responses to sound are highly variable and context-
specific. Many different variables can influence an animal's perception
of and response to (in both nature and magnitude) an acoustic event. An
animal's prior experience with a sound or sound source affects whether
it is less likely (habituation) or more likely (sensitization) to
respond to certain sounds in the future (animals can also be innately
pre-disposed to respond to certain sounds in certain ways; Southall et
al., 2007). Related to the sound itself, the perceived nearness of the
sound, bearing of the sound (approaching vs. retreating), similarity of
a sound to biologically relevant sounds in the animal's environment
(i.e., calls of predators, prey, or conspecifics), and familiarity of
the sound may affect the way an animal responds to the sound (Southall
et al., 2007). Individuals (of different age, gender, reproductive
status, etc.) among most populations will have variable hearing
capabilities and differing behavioral sensitivities to sounds that will
be affected by prior conditioning, experience, and current activities
of those individuals. Often, specific acoustic features of the sound
and contextual variables (i.e., proximity, duration, or recurrence of
the sound or the current behavior that the marine
[[Page 12551]]
mammal is engaged in or its prior experience), as well as entirely
separate factors such as the physical presence of a nearby vessel, may
be more relevant to the animal's response than the received level
alone.
Exposure of marine mammals to sound sources can result in (but is
not limited to) no response or any of the following observable
responses: increased alertness; orientation or attraction to a sound
source; vocal modifications; cessation of feeding; cessation of social
interaction; alteration of movement or diving behavior; avoidance;
habitat abandonment (temporary or permanent); and, in severe cases,
panic, flight, stampede, or stranding, potentially resulting in death
(Southall et al., 2007). On a related note, many animals perform vital
functions, such as feeding, resting, traveling, and socializing, on a
diel cycle (24-hr cycle). Behavioral reactions to noise exposure (such
as disruption of critical life functions, displacement, or avoidance of
important habitat) are more likely to be significant if they last more
than one diel cycle or recur on subsequent days (Southall et al.,
2007). Consequently, a behavioral response lasting less than one day
and not recurring on subsequent days is not considered particularly
severe unless it could directly affect reproduction or survival
(Southall et al., 2007).
Detailed studies regarding responses to anthropogenic sound have
been conducted on humpback, gray, and bowhead whales and ringed seals.
Less detailed data are available for some other species of baleen
whales, sperm whales, small toothed whales, and sea otters. The
following sub-sections provide examples of behavioral responses that
provide an idea of the variability in behavioral responses that would
be expected given the different sensitivities of marine mammal species
to sound.
Baleen Whales--Richardson et al. (1995a) reported changes in
surfacing and respiration behavior and the occurrence of turns during
surfacing in bowhead whales exposed to playback of underwater sound
from drilling activities. These behavioral effects were localized and
occurred at distances up to 1.2-2.5 mi (2-4 km).
Some bowheads appeared to divert from their migratory path after
exposure to projected icebreaker sounds. Other bowheads however,
tolerated projected icebreaker sound at levels 20 dB and more above
ambient sound levels. The source level of the projected sound however,
was much less than that of an actual icebreaker, and reaction distances
to actual icebreaking may be much greater than those reported here for
projected sounds. However, icebreaking is not a component of COP's
proposed operations.
Brewer et al. (1993) and Hall et al. (1994) reported numerous
sightings of marine mammals including bowhead whales in the vicinity of
offshore drilling operations in the Beaufort Sea. One bowhead whale
sighting was reported within approximately 1,312 ft (400 m) of a
drilling vessel although most other bowhead sightings were at much
greater distances. Few bowheads were recorded near industrial
activities by aerial observers. After controlling for spatial
autocorrelation in aerial survey data from Hall et al. (1994) using a
Mantel test, Schick and Urban (2000) found that the variable describing
straight line distance between the rig and bowhead whale sightings was
not significant but that a variable describing threshold distances
between sightings and the rig was significant. Thus, although the
aerial survey results suggested substantial avoidance of the operations
by bowhead whales, observations by vessel-based observers indicate that
at least some bowheads may have been closer to industrial activities
than was suggested by results of aerial observations.
Richardson et al. (2008) reported a slight change in the
distribution of bowhead whale calls in response to operational sounds
on BP's Northstar Island. The southern edge of the call distribution
ranged from 0.47 to 1.46 mi (0.76 to 2.35 km) farther offshore,
apparently in response to industrial sound levels. This result however,
was only achieved after intensive statistical analyses, and it is not
clear that this represented a biologically significant effect.
Patenaude et al. (2002) reported fewer behavioral responses to
aircraft overflights by bowhead compared to beluga whales. Behaviors
classified as reactions consisted of short surfacings, immediate dives
or turns, changes in behavior state, vigorous swimming, and breaching.
Most bowhead reaction resulted from exposure to helicopter activity and
little response to fixed-wing aircraft was observed. Most reactions
occurred when the helicopter was at altitudes <=492 ft (150 m) and
lateral distances <=820 ft (250 m; Nowacek et al., 2007).
During their study, Patenaude et al. (2002) observed one bowhead
whale cow-calf pair during four passes totaling 2.8 hours of the
helicopter and two pairs during Twin Otter overflights. All of the
helicopter passes were at altitudes of 49-98 ft (15-30 m). The mother
dove both times she was at the surface, and the calf dove once out of
the four times it was at the surface. For the cow-calf pair sightings
during Twin Otter overflights, the authors did not note any behaviors
specific to those pairs. Rather, the reactions of the cow-calf pairs
were lumped with the reactions of other groups that did not consist of
calves.
Richardson et al. (1995a) and Moore and Clarke (2002) reviewed a
few studies that observed responses of gray whales to aircraft. Cow-
calf pairs were quite sensitive to a turboprop survey flown at 1,000 ft
(305 m) altitude on the Alaskan summering grounds. In that survey,
adults were seen swimming over the calf, or the calf swam under the
adult (Ljungblad et al., 1983, cited in Richardson et al., 1995b and
Moore and Clarke, 2002). However, when the same aircraft circled for
more than 10 minutes at 1,050 ft (320 m) altitude over a group of
mating gray whales, no reactions were observed (Ljungblad et al., 1987,
cited in Moore and Clarke, 2002). Malme et al. (1984, cited in
Richardson et al., 1995b and Moore and Clarke, 2002) conducted playback
experiments on migrating gray whales. They exposed the animals to
underwater noise recorded from a Bell 212 helicopter (estimated
altitude=328 ft [100 m]), at an average of three simulated passes per
minute. The authors observed that whales changed their swimming course
and sometimes slowed down in response to the playback sound but
proceeded to migrate past the transducer. Migrating gray whales did not
react overtly to a Bell 212 helicopter at greater than 1,394 ft (425 m)
altitude, occasionally reacted when the helicopter was at 1,000-1,198
ft (305-365 m), and usually reacted when it was below 825 ft (250 m;
Southwest Research Associates, 1988, cited in Richardson et al., 1995b
and Moore and Clarke, 2002). Reactions noted in that study included
abrupt turns or dives or both. Green et al. (1992, cited in Richardson
et al., 1995b) observed that migrating gray whales rarely exhibited
noticeable reactions to a straight-line overflight by a Twin Otter at
197 ft (60 m) altitude. Restrictions on aircraft altitude will be part
of the proposed mitigation measures (described in the ``Proposed
Mitigation'' section later in this document) during the proposed
drilling activities, and overflights are likely to have little or no
disturbance effects on baleen whales. Any disturbance that may occur
would likely be temporary and localized.
Southall et al. (2007, Appendix C) reviewed a number of papers
describing the responses of marine mammals to non-pulsed sound, such as
that produced during exploratory drilling
[[Page 12552]]
operations. In general, little or no response was observed in animals
exposed at received levels from 90-120 dB re 1 [mu]Pa (rms).
Probability of avoidance and other behavioral effects increased when
received levels were from 120-160 dB re 1 [mu]Pa (rms). Some of the
relevant reviews contained in Southall et al. (2007) are summarized
next.
Baker et al. (1982) reported some avoidance by humpback whales to
vessel noise when received levels were 110-120 dB (rms) and clear
avoidance at 120-140 dB (sound measurements were not provided by Baker
but were based on measurements of identical vessels by Miles and Malme,
1983).
Malme et al. (1983, 1984) used playbacks of sounds from helicopter
overflight and drilling rigs and platforms to study behavioral effects
on migrating gray whales. Received levels exceeding 120 dB induced
avoidance reactions. Malme et al. (1984) calculated 10%, 50%, and 90%
probabilities of gray whale avoidance reactions at received levels of
110, 120, and 130 dB, respectively. Malme et al. (1986) observed the
behavior of feeding gray whales during four experimental playbacks of
drilling sounds (50 to 315 Hz; 21- min overall duration and 10% duty
cycle; source levels of 156-162 dB). In two cases for received levels
of 100-110 dB, no behavioral reaction was observed. However, avoidance
behavior was observed in two cases where received levels were 110-120
dB.
Richardson et al. (1990) performed 12 playback experiments in which
bowhead whales in the Alaskan Arctic were exposed to drilling sounds.
Whales generally did not respond to exposures in the 100 to 130 dB
range, although there was some indication of minor behavioral changes
in several instances.
McCauley et al. (1996) reported several cases of humpback whales
responding to vessels in Hervey Bay, Australia. Results indicated clear
avoidance at received levels between 118 to 124 dB in three cases for
which response and received levels were observed/measured.
Palka and Hammond (2001) analyzed line transect census data in
which the orientation and distance off transect line were reported for
large numbers of minke whales. The authors developed a method to
account for effects of animal movement in response to sighting
platforms. Minor changes in locomotion speed, direction, and/or diving
profile were reported at ranges from 1,847 to 2,352 ft (563 to 717 m)
at received levels of 110 to 120 dB.
Biassoni et al. (2000) and Miller et al. (2000) reported behavioral
observations for humpback whales exposed to a low-frequency sonar
stimulus (160- to 330-Hz frequency band; 42-s tonal signal repeated
every 6 min; source levels 170 to 200 dB) during playback experiments.
Exposure to measured received levels ranging from 120 to 150 dB
resulted in variability in humpback singing behavior. Croll et al.
(2001) investigated responses of foraging fin and blue whales to the
same low frequency active sonar stimulus off southern California.
Playbacks and control intervals with no transmission were used to
investigate behavior and distribution on time scales of several weeks
and spatial scales of tens of kilometers. The general conclusion was
that whales remained feeding within a region for which 12 to 30 percent
of exposures exceeded 140 dB.
Frankel and Clark (1998) conducted playback experiments with
wintering humpback whales using a single speaker producing a low-
frequency ``M-sequence'' (sine wave with multiple-phase reversals)
signal in the 60 to 90 Hz band with output of 172 dB at 1 m. For 11
playbacks, exposures were between 120 and 130 dB re 1 [mu]Pa (rms) and
included sufficient information regarding individual responses. During
eight of the trials, there were no measurable differences in tracks or
bearings relative to control conditions, whereas on three occasions,
whales either moved slightly away from (n = 1) or towards (n = 2) the
playback speaker during exposure. The presence of the source vessel
itself had a greater effect than did the M-sequence playback.
Finally, Nowacek et al. (2004) used controlled exposures to
demonstrate behavioral reactions of northern right whales to various
non-pulse sounds. Playback stimuli included ship noise, social sounds
of conspecifics, and a complex, 18-min ``alert'' sound consisting of
repetitions of three different artificial signals. Ten whales were
tagged with calibrated instruments that measured received sound
characteristics and concurrent animal movements in three dimensions.
Five out of six exposed whales reacted strongly to alert signals at
measured received levels between 130 and 150 dB (i.e., ceased foraging
and swam rapidly to the surface). Two of these individuals were not
exposed to ship noise, and the other four were exposed to both stimuli.
These whales reacted mildly to conspecific signals. Seven whales,
including the four exposed to the alert stimulus, had no measurable
response to either ship sounds or actual vessel noise.
Toothed Whales--Most toothed whales have the greatest hearing
sensitivity at frequencies much higher than that of baleen whales and
may be less responsive to low-frequency sound commonly associated with
oil and gas industry exploratory drilling activities. Richardson et al.
(1995a) reported that beluga whales did not show any apparent reaction
to playback of underwater drilling sounds at distances greater than
656-1,312 ft (200-400 m). Reactions included slowing down, milling, or
reversal of course after which the whales continued past the projector,
sometimes within 164-328 ft (50-100 m). The authors concluded (based on
a small sample size) that the playback of drilling sounds had no
biologically significant effects on migration routes of beluga whales
migrating through pack ice and along the seaward side of the nearshore
lead east of Point Barrow in spring.
At least six of 17 groups of beluga whales appeared to alter their
migration path in response to underwater playbacks of icebreaker sound
(Richardson et al., 1995a). Received levels from the icebreaker
playback were estimated at 78-84 dB in the 1/3-octave band centered at
5,000 Hz, or 8-14 dB above ambient. If beluga whales reacted to an
actual icebreaker at received levels of 80 dB, reactions would be
expected to occur at distances on the order of 6.2 mi (10 km). Finley
et al. (1990) also reported beluga avoidance of icebreaker activities
in the Canadian High Arctic at distances of 22-31 mi (35-50 km). In
addition to avoidance, changes in dive behavior and pod integrity were
also noted.
Patenaude et al. (2002) reported that beluga whales appeared to be
more responsive to aircraft overflights than bowhead whales. Changes
were observed in diving and respiration behavior, and some whales
veered away when a helicopter passed at <=820 ft (250 m) lateral
distance at altitudes up to 492 ft (150 m). However, some belugas
showed no reaction to the helicopter. Belugas appeared to show less
response to fixed-wing aircraft than to helicopter overflights.
In reviewing responses of cetaceans with best hearing in mid-
frequency ranges, which includes toothed whales, Southall et al. (2007)
reported that combined field and laboratory data for mid-frequency
cetaceans exposed to non-pulse sounds did not lead to a clear
conclusion about received levels coincident with various behavioral
responses. In some settings, individuals in the field showed profound
(significant) behavioral responses to exposures from 90-120 dB, while
others failed to exhibit such responses for exposure to received levels
from 120-
[[Page 12553]]
150 dB. Contextual variables other than exposure received level, and
probable species differences, are the likely reasons for this
variability. Context, including the fact that captive subjects were
often directly reinforced with food for tolerating noise exposure, may
also explain why there was great disparity in results from field and
laboratory conditions--exposures in captive settings generally exceeded
170 dB before inducing behavioral responses. A summary of some of the
relevant material reviewed by Southall et al. (2007) is next.
LGL and Greeneridge (1986) and Finley et al. (1990) documented
belugas and narwhals congregated near ice edges reacting to the
approach and passage of icebreaking ships. Beluga whales responded to
oncoming vessels by (1) Fleeing at speeds of up to 12.4 mi/hr (20 km/
hr) from distances of 12.4-50 mi (20-80 km), (2) abandoning normal pod
structure, and (3) modifying vocal behavior and/or emitting alarm
calls. Narwhals, in contrast, generally demonstrated a ``freeze''
response, lying motionless or swimming slowly away (as far as 23 mi [37
km] down the ice edge), huddling in groups, and ceasing sound
production. There was some evidence of habituation and reduced
avoidance 2 to 3 days after onset.
The 1982 season observations by LGL and Greeneridge (1986) involved
a single passage of an icebreaker with both ice-based and aerial
measurements on June 28, 1982. Four groups of narwhals (n = 9 to 10, 7,
7, and 6) responded when the ship was 4 mi (6.4 km) away (received
levels of approximately 100 dB in the 150- to 1,150-Hz band). At a
later point, observers sighted belugas moving away from the source at
more than 12.4 mi (20 km; received levels of approximately 90 dB in the
150- to 1,150-Hz band). The total number of animals observed fleeing
was about 300, suggesting approximately 100 independent groups (of
three individuals each). No whales were sighted the following day, but
some were sighted on June 30, with ship noise audible at spectrum
levels of approximately 55 dB/Hz (up to 4 kHz).
Observations during 1983 (LGL and Greeneridge, 1986) involved two
icebreaking ships with aerial survey and ice-based observations during
seven sampling periods. Narwhals and belugas generally reacted at
received levels ranging from 101 to 121 dB in the 20- to 1,000-Hz band
and at a distance of up to 40.4 mi (65 km). Large numbers (100s) of
beluga whales moved out of the area at higher received levels. As noise
levels from icebreaking operations diminished, a total of 45 narwhals
returned to the area and engaged in diving and foraging behavior.
During the final sampling period, following an 8-h quiet interval, no
reactions were seen from 28 narwhals and 17 belugas (at received levels
ranging up to 115 dB).
The final season (1984) reported in LGL and Greeneridge (1986)
involved aerial surveys before, during, and after the passage of two
icebreaking ships. During operations, no belugas and few narwhals were
observed in an area approximately 16.8 mi (27 km) ahead of the vessels,
and all whales sighted over 12.4-50 mi (20-80 km) from the ships were
swimming strongly away. Additional observations confirmed the spatial
extent of avoidance reactions to this sound source in this context.
Buckstaff (2004) reported elevated dolphin whistle rates with
received levels from oncoming vessels in the 110 to 120 dB range in
Sarasota Bay, Florida. These hearing thresholds were apparently lower
than those reported by a researcher listening with towed hydrophones.
Morisaka et al. (2005) compared whistles from three populations of
Indo-Pacific bottlenose dolphins. One population was exposed to vessel
noise with spectrum levels of approximately 85 dB/Hz in the 1- to 22-
kHz band (broadband received levels approximately 128 dB) as opposed to
approximately 65 dB/Hz in the same band (broadband received levels
approximately 108 dB) for the other two sites. Dolphin whistles in the
noisier environment had lower fundamental frequencies and less
frequency modulation, suggesting a shift in sound parameters as a
result of increased ambient noise.
Morton and Symonds (2002) used census data on killer whales in
British Columbia to evaluate avoidance of non-pulse acoustic harassment
devices (AHDs). Avoidance ranges were about 2.5 mi (4 km). Also, there
was a dramatic reduction in the number of days ``resident'' killer
whales were sighted during AHD-active periods compared to pre- and
post-exposure periods and a nearby control site.
Monteiro-Neto et al. (2004) studied avoidance responses of tucuxi
(Sotalia fluviatilis) to Dukane[supreg] Netmark acoustic deterrent
devices. In a total of 30 exposure trials, approximately five groups
each demonstrated significant avoidance compared to 20 pinger off and
55 no-pinger control trials over two quadrats of about 0.19 mi\2\ (0.5
km\2\). Estimated exposure received levels were approximately 115 dB.
Awbrey and Stewart (1983) played back semi-submersible drillship
sounds (source level: 163 dB) to belugas in Alaska. They reported
avoidance reactions at 984 and 4,921 ft (300 and 1,500 m) and approach
by groups at a distance of 2.2 mi (3.5 km; received levels were
approximately 110 to 145 dB over these ranges assuming a 15 log R
transmission loss). Similarly, Richardson et al. (1990) played back
drilling platform sounds (source level: 163 dB) to belugas in Alaska.
They conducted aerial observations of eight individuals among
approximately 100 spread over an area several hundred meters to several
kilometers from the sound source and found no obvious reactions.
Moderate changes in movement were noted for three groups swimming
within 656 ft (200 m) of the sound projector.
Two studies deal with issues related to changes in marine mammal
vocal behavior as a function of variable background noise levels. Foote
et al. (2004) found increases in the duration of killer whale calls
over the period 1977 to 2003, during which time vessel traffic in Puget
Sound, and particularly whale-watching boats around the animals,
increased dramatically. Scheifele et al. (2005) demonstrated that
belugas in the St. Lawrence River increased the levels of their
vocalizations as a function of the background noise level (the
``Lombard Effect'').
Several researchers conducting laboratory experiments on hearing
and the effects of non-pulse sounds on hearing in mid-frequency
cetaceans have reported concurrent behavioral responses. Nachtigall et
al. (2003) reported that noise exposures up to 179 dB and 55-min
duration affected the trained behaviors of a bottlenose dolphin
participating in a TTS experiment. Finneran and Schlundt (2004)
provided a detailed, comprehensive analysis of the behavioral responses
of belugas and bottlenose dolphins to 1-s tones (received levels 160 to
202 dB) in the context of TTS experiments. Romano et al. (2004)
investigated the physiological responses of a bottlenose dolphin and a
beluga exposed to these tonal exposures and demonstrated a decrease in
blood cortisol levels during a series of exposures between 130 and 201
dB. Collectively, the laboratory observations suggested the onset of a
behavioral response at higher received levels than did field studies.
The differences were likely related to the very different conditions
and contextual variables between untrained, free-ranging individuals
vs. laboratory subjects that were rewarded with food for tolerating
noise exposure.
Pinnipeds--Pinnipeds generally seem to be less responsive to
exposure to
[[Page 12554]]
industrial sound than most cetaceans. Pinniped responses to underwater
sound from some types of industrial activities such as seismic
exploration appear to be temporary and localized (Harris et al., 2001;
Reiser et al., 2009).
Blackwell et al. (2004) reported little or no reaction of ringed
seals in response to pile-driving activities during construction of a
man-made island in the Beaufort Sea. Ringed seals were observed
swimming as close as 151 ft (46 m) from the island and may have been
habituated to the sounds which were likely audible at distances <9,842
ft (3,000 m) underwater and 0.3 mi (0.5 km) in air. Moulton et al.
(2003) reported that ringed seal densities on ice in the vicinity of a
man-made island in the Beaufort Sea did not change significantly before
and after construction and drilling activities.
Southall et al. (2007) reviewed literature describing responses of
pinnipeds to non-pulsed sound and reported that the limited data
suggest exposures between approximately 90 and 140 dB generally do not
appear to induce strong behavioral responses in pinnipeds exposed to
non-pulse sounds in water; no data exist regarding exposures at higher
levels. It is important to note that among these studies, there are
some apparent differences in responses between field and laboratory
conditions. In contrast to the mid-frequency odontocetes, captive
pinnipeds responded more strongly at lower levels than did animals in
the field. Again, contextual issues are the likely cause of this
difference.
Jacobs and Terhune (2002) observed harbor seal reactions to AHDs
(source level in this study was 172 dB) deployed around aquaculture
sites. Seals were generally unresponsive to sounds from the AHDs.
During two specific events, individuals came within 141 and 144 ft (43
and 44 m) of active AHDs and failed to demonstrate any measurable
behavioral response; estimated received levels based on the measures
given were approximately 120 to 130 dB.
Costa et al. (2003) measured received noise levels from an Acoustic
Thermometry of Ocean Climate (ATOC) program sound source off northern
California using acoustic data loggers placed on translocated elephant
seals. Subjects were captured on land, transported to sea, instrumented
with archival acoustic tags, and released such that their transit would
lead them near an active ATOC source (at 939-m depth; 75-Hz signal with
37.5- Hz bandwidth; 195 dB maximum source level, ramped up from 165 dB
over 20 min) on their return to a haul-out site. Received exposure
levels of the ATOC source for experimental subjects averaged 128 dB
(range 118 to 137) in the 60- to 90-Hz band. None of the instrumented
animals terminated dives or radically altered behavior upon exposure,
but some statistically significant changes in diving parameters were
documented in nine individuals. Translocated northern elephant seals
exposed to this particular non-pulse source began to demonstrate subtle
behavioral changes at exposure to received levels of approximately 120
to 140 dB.
Kastelein et al. (2006) exposed nine captive harbor seals in an
approximately 82 x 98 ft (25 x 30 m) enclosure to non-pulse sounds used
in underwater data communication systems (similar to acoustic modems).
Test signals were frequency modulated tones, sweeps, and bands of noise
with fundamental frequencies between 8 and 16 kHz; 128 to 130 [ 3] dB source levels; 1- to 2-s duration [60-80 percent duty
cycle]; or 100 percent duty cycle. They recorded seal positions and the
mean number of individual surfacing behaviors during control periods
(no exposure), before exposure, and in 15-min experimental sessions (n
= 7 exposures for each sound type). Seals generally swam away from each
source at received levels of approximately 107 dB, avoiding it by
approximately 16 ft (5 m), although they did not haul out of the water
or change surfacing behavior. Seal reactions did not appear to wane
over repeated exposure (i.e., there was no obvious habituation), and
the colony of seals generally returned to baseline conditions following
exposure. The seals were not reinforced with food for remaining in the
sound field.
Potential effects to pinnipeds from aircraft activity could involve
both acoustic and non-acoustic effects. It is uncertain if the seals
react to the sound of the helicopter or to its physical presence flying
overhead. Typical reactions of hauled out pinnipeds to aircraft that
have been observed include looking up at the aircraft, moving on the
ice or land, entering a breathing hole or crack in the ice, or entering
the water. Ice seals hauled out on the ice have been observed diving
into the water when approached by a low-flying aircraft or helicopter
(Burns and Harbo, 1972, cited in Richardson et al., 1995a; Burns and
Frost, 1979, cited in Richardson et al., 1995a). Richardson et al.
(1995a) note that responses can vary based on differences in aircraft
type, altitude, and flight pattern. Additionally, a study conducted by
Born et al. (1999) found that wind chill was also a factor in level of
response of ringed seals hauled out on ice, as well as time of day and
relative wind direction.
Blackwell et al. (2004a) observed 12 ringed seals during low-
altitude overflights of a Bell 212 helicopter at Northstar in June and
July 2000 (9 observations took place concurrent with pipe-driving
activities). One seal showed no reaction to the aircraft while the
remaining 11 (92%) reacted, either by looking at the helicopter (n=10)
or by departing from their basking site (n=1). Blackwell et al. (2004a)
concluded that none of the reactions to helicopters were strong or long
lasting, and that seals near Northstar in June and July 2000 probably
had habituated to industrial sounds and visible activities that had
occurred often during the preceding winter and spring. There have been
few systematic studies of pinniped reactions to aircraft overflights,
and most of the available data concern pinnipeds hauled out on land or
ice rather than pinnipeds in the water (Richardson et al., 1995a; Born
et al., 1999).
Born et al. (1999) determined that 49 percent of ringed seals
escaped (i.e., left the ice) as a response to a helicopter flying at
492 ft (150 m) altitude. Seals entered the water when the helicopter
was 4,101 ft (1,250 m) away if the seal was in front of the helicopter
and at 1,640 ft (500 m) away if the seal was to the side of the
helicopter. The authors noted that more seals reacted to helicopters
than to fixed-wing aircraft. The study concluded that the risk of
scaring ringed seals by small-type helicopters could be substantially
reduced if they do not approach closer than 4,921 ft (1,500 m).
Spotted seals hauled out on land in summer are unusually sensitive
to aircraft overflights compared to other species. They often rush into
the water when an aircraft flies by at altitudes up to 984-2,461 ft
(300-750 m). They occasionally react to aircraft flying as high as
4,495 ft (1,370 m) and at lateral distances as far as 1.2 mi (2 km) or
more (Frost and Lowry, 1990; Rugh et al., 1997).
(4) Hearing Impairment and Other Physiological Effects
Temporary or permanent hearing impairment is a possibility when
marine mammals are exposed to very strong sounds. Non-auditory
physiological effects might also occur in marine mammals exposed to
strong underwater sound. Possible types of non-auditory physiological
effects or injuries that theoretically might occur in mammals close to
a strong sound source include stress, neurological effects, bubble
formation, and other types of organ or tissue damage. It is possible
that some
[[Page 12555]]
marine mammal species (i.e., beaked whales) may be especially
susceptible to injury and/or stranding when exposed to strong pulsed
sounds. However, as discussed later in this document, there is no
definitive evidence that any of these effects occur even for marine
mammals in close proximity to industrial sound sources, and beaked
whales do not occur in the proposed activity area. Additional
information regarding the possibilities of TTS, permanent threshold
shift (PTS), and non-auditory physiological effects, such as stress, is
discussed for both exploratory drilling activities and VSP surveys in
the following section (``Potential Effects from VSP Activities'').
Potential Effects from VSP Activities
(1) Tolerance
Numerous studies have shown that pulsed sounds from airguns are
often readily detectable in the water at distances of many kilometers.
Weir (2008) observed marine mammal responses to seismic pulses from a
24 airgun array firing a total volume of either 5,085 in\3\ or 3,147
in\3\ in Angolan waters between August 2004 and May 2005. Weir recorded
a total of 207 sightings of humpback whales (n = 66), sperm whales (n =
124), and Atlantic spotted dolphins (n = 17) and reported that there
were no significant differences in encounter rates (sightings/hr) for
humpback and sperm whales according to the airgun array's operational
status (i.e., active versus silent). For additional information on
tolerance of marine mammals to anthropogenic sound, see the previous
subsection in this document (``Potential Effects from Exploratory
Drilling Activities'').
(2) Masking
As stated earlier in this document, masking is the obscuring of
sounds of interest by other sounds, often at similar frequencies. For
full details about masking, see the previous subsection in this
document (``Potential Effects from Exploratory Drilling Activities'').
Some additional information regarding pulsed sounds is provided here.
There is evidence of some marine mammal species continuing to call
in the presence of industrial activity. McDonald et al. (1995) heard
blue and fin whale calls between seismic pulses in the Pacific.
Although there has been one report that sperm whales cease calling when
exposed to pulses from a very distant seismic ship (Bowles et al.,
1994), a more recent study reported that sperm whales off northern
Norway continued calling in the presence of seismic pulses (Madsen et
al., 2002). Similar results were also reported during work in the Gulf
of Mexico (Tyack et al., 2003). Bowhead whale calls are frequently
detected in the presence of seismic pulses, although the numbers of
calls detected may sometimes be reduced (Richardson et al., 1986;
Greene et al., 1999; Blackwell et al., 2009a). Bowhead whales in the
Beaufort Sea may decrease their call rates in response to seismic
operations, although movement out of the area might also have
contributed to the lower call detection rate (Blackwell et al.,
2009a,b). Additionally, there is increasing evidence that, at times,
there is enough reverberation between airgun pulses such that detection
range of calls may be significantly reduced. In contrast, Di Iorio and
Clark (2009) found evidence of increased calling by blue whales during
operations by a lower-energy seismic source, a sparker.
There is little concern regarding masking due to the brief duration
of these pulses and relatively longer silence between airgun shots (9-
12 seconds) near the sound source. However, at long distances (over
tens of kilometers away) in deep water, due to multipath propagation
and reverberation, the durations of airgun pulses can be ``stretched''
to seconds with long decays (Madsen et al., 2006; Clark and Gagnon,
2006). Therefore it could affect communication signals used by low
frequency mysticetes when they occur near the noise band and thus
reduce the communication space of animals (e.g., Clark et al., 2009a,b)
and cause increased stress levels (e.g., Foote et al., 2004; Holt et
al., 2009). Nevertheless, the intensity of the noise is also greatly
reduced at long distances. Therefore, masking effects are anticipated
to be limited, especially in the case of odontocetes, given that they
typically communicate at frequencies higher than those of the airguns.
Moreover, because of the extremely short time period over which airguns
will be used during operations (a total of 2 hrs per well), masking is
not anticipated to occur.
(3) Behavioral Disturbance Reactions
As was described in more detail in the previous sub-section
(``Potential Effects of Exploratory Drilling Activities''), behavioral
responses to sound are highly variable and context-specific. Summaries
of observed reactions and studies are provided next.
Baleen Whales--Baleen whale responses to pulsed sound (e.g.,
seismic airguns) have been studied more thoroughly than responses to
continuous sound (e.g., drillships). Baleen whales generally tend to
avoid operating airguns, but avoidance radii are quite variable. Whales
are often reported to show no overt reactions to pulses from large
arrays of airguns at distances beyond a few kilometers, even though the
airgun pulses remain well above ambient noise levels out to much
greater distances (Miller et al., 2005). However, baleen whales exposed
to strong noise pulses often react by deviating from their normal
migration route (Richardson et al., 1999). Migrating gray and bowhead
whales were observed avoiding the sound source by displacing their
migration route to varying degrees but within the natural boundaries of
the migration corridors (Schick and Urban, 2000; Richardson et al.,
1999; Malme et al., 1983). Baleen whale responses to pulsed sound
however may depend on the type of activity in which the whales are
engaged. Some evidence suggests that feeding bowhead whales may be more
tolerant of underwater sound than migrating bowheads (Miller et al.,
2005; Lyons et al., 2009; Christie et al., 2010).
Results of studies of gray, bowhead, and humpback whales have
determined that received levels of pulses in the 160-170 dB re 1 [mu]Pa
rms range seem to cause obvious avoidance behavior in a substantial
fraction of the animals exposed. In many areas, seismic pulses from
large arrays of airguns diminish to those levels at distances ranging
from 2.8-9 mi (4.5-14.5 km) from the source. For the much smaller
airgun array used during the VSP survey (total discharge volume of 760
in\3\), distances to received levels in the 170-160 dB re 1 [mu]Pa rms
range are estimated to be 1.44-3 mi (2.31-5 km). Baleen whales within
those distances may show avoidance or other strong disturbance
reactions to the airgun array. Subtle behavioral changes sometimes
become evident at somewhat lower received levels, and recent studies
have shown that some species of baleen whales, notably bowhead and
humpback whales, at times show strong avoidance at received levels
lower than 160-170 dB re 1 [mu]Pa rms. Bowhead whales migrating west
across the Alaskan Beaufort Sea in autumn, in particular, are unusually
responsive, with avoidance occurring out to distances of 12.4-18.6 mi
(20-30 km) from a medium-sized airgun source (Miller et al., 1999;
Richardson et al., 1999). However, more recent research on bowhead
whales (Miller et al., 2005) corroborates earlier evidence that, during
the summer feeding season, bowheads are not as sensitive to seismic
sources. In summer, bowheads typically
[[Page 12556]]
begin to show avoidance reactions at a received level of about 160-170
dB re 1 [micro]Pa rms (Richardson et al., 1986; Ljungblad et al., 1988;
Miller et al., 2005).
Malme et al. (1986, 1988) studied the responses of feeding eastern
gray whales to pulses from a single 100 in\3\ airgun off St. Lawrence
Island in the northern Bering Sea. They estimated, based on small
sample sizes, that 50% of feeding gray whales ceased feeding at an
average received pressure level of 173 dB re 1 [mu]Pa on an
(approximate) rms basis, and that 10% of feeding whales interrupted
feeding at received levels of 163 dB. Those findings were generally
consistent with the results of experiments conducted on larger numbers
of gray whales that were migrating along the California coast and on
observations of the distribution of feeding Western Pacific gray whales
off Sakhalin Island, Russia, during a seismic survey (Yazvenko et al.,
2007).
Data on short-term reactions (or lack of reactions) of cetaceans to
impulsive noises do not necessarily provide information about long-term
effects. While it is not certain whether impulsive noises affect
reproductive rate or distribution and habitat use in subsequent days or
years, certain species have continued to use areas ensonified by
airguns and have continued to increase in number despite successive
years of anthropogenic activity in the area. Gray whales continued to
migrate annually along the west coast of North America despite
intermittent seismic exploration and much ship traffic in that area for
decades (Appendix A in Malme et al., 1984). Bowhead whales continued to
travel to the eastern Beaufort Sea each summer despite seismic
exploration in their summer and autumn range for many years (Richardson
et al., 1987). Populations of both gray whales and bowhead whales grew
substantially during this time. Bowhead whales have increased by
approximately 3.4% per year for the last 10 years in the Beaufort Sea
(Allen and Angliss, 2012). In any event, the brief exposures to sound
pulses from the proposed airgun source (the airguns will only be fired
for a period of 2 hrs for each of the two wells) are highly unlikely to
result in prolonged effects.
Toothed Whales--Few systematic data are available describing
reactions of toothed whales to noise pulses. Few studies similar to the
more extensive baleen whale/seismic pulse work summarized earlier in
this document have been reported for toothed whales. However,
systematic work on sperm whales is underway (Tyack et al., 2003), and
there is an increasing amount of information about responses of various
odontocetes to seismic surveys based on monitoring studies (e.g.,
Stone, 2003; Smultea et al., 2004; Moulton and Miller, 2005).
Seismic operators and marine mammal observers sometimes see
dolphins and other small toothed whales near operating airgun arrays,
but, in general, there seems to be a tendency for most delphinids to
show some limited avoidance of seismic vessels operating large airgun
systems. However, some dolphins seem to be attracted to the seismic
vessel and floats, and some ride the bow wave of the seismic vessel
even when large arrays of airguns are firing. Nonetheless, there have
been indications that small toothed whales sometimes move away or
maintain a somewhat greater distance from the vessel when a large array
of airguns is operating than when it is silent (e.g., Goold, 1996a, b,
c; Calambokidis and Osmek, 1998; Stone, 2003). The beluga may be a
species that (at least at times) shows long-distance avoidance of
seismic vessels. Aerial surveys during seismic operations in the
southeastern Beaufort Sea recorded much lower sighting rates of beluga
whales within 6.2-12.4 mi (10-20 km) of an active seismic vessel. These
results were consistent with the low number of beluga sightings
reported by observers aboard the seismic vessel, suggesting that some
belugas might be avoiding the seismic operations at distances of 6.2-
12.4 mi (10-20 km) (Miller et al., 2005).
Captive bottlenose dolphins and (of more relevance in this project)
beluga whales exhibit changes in behavior when exposed to strong pulsed
sounds similar in duration to those typically used in seismic surveys
(Finneran et al., 2002, 2005). However, the animals tolerated high
received levels of sound (p-p level >200 dB re 1 [mu]Pa) before
exhibiting aversive behaviors.
Reactions of toothed whales to large arrays of airguns are variable
and, at least for delphinids, seem to be confined to a smaller radius
than has been observed for mysticetes. However, based on the limited
existing evidence, belugas should not be grouped with delphinids in the
``less responsive'' category.
Pinnipeds--Pinnipeds are not likely to show a strong avoidance
reaction to the airgun sources proposed for use. Visual monitoring from
seismic vessels has shown only slight (if any) avoidance of airguns by
pinnipeds and only slight (if any) changes in behavior. Ringed seals
frequently do not avoid the area within a few hundred meters of
operating airgun arrays (Harris et al., 2001; Moulton and Lawson, 2002;
Miller et al., 2005). Monitoring work in the Alaskan Beaufort Sea
during 1996-2001 provided considerable information regarding the
behavior of seals exposed to seismic pulses (Harris et al., 2001;
Moulton and Lawson, 2002). These seismic projects usually involved
arrays of 6 to 16 airguns with total volumes of 560 to 1,500 in\3\. The
combined results suggest that some seals avoid the immediate area
around seismic vessels. In most survey years, ringed seal sightings
tended to be farther away from the seismic vessel when the airguns were
operating than when they were not (Moulton and Lawson, 2002). However,
these avoidance movements were relatively small, on the order of 328 ft
(100 m) to a few hundreds of meters, and many seals remained within
328-656 ft (100-200 m) of the trackline as the operating airgun array
passed by. Seal sighting rates at the water surface were lower during
airgun array operations than during no-airgun periods in each survey
year except 1997. Similarly, seals are often very tolerant of pulsed
sounds from seal-scaring devices (Mate and Harvey, 1987; Jefferson and
Curry, 1994; Richardson et al., 1995a). However, initial telemetry work
suggests that avoidance and other behavioral reactions by two other
species of seals to small airgun sources may at times be stronger than
evident to date from visual studies of pinniped reactions to airguns
(Thompson et al., 1998). Even if reactions of the species occurring in
the present study area are as strong as those evident in the telemetry
study, reactions are expected to be confined to relatively small
distances and durations, with no long-term effects on pinniped
individuals or populations. Additionally, the airguns are only proposed
to be used for a very short time during the entire exploration drilling
program (approximately 2 hrs for each well, for a total of 4 hrs over
the entire open-water season, which lasts for approximately 4 months,
if both wells are drilled).
(4) Hearing Impairment and Other Physiological Effects
TTS--TTS is the mildest form of hearing impairment that can occur
during exposure to a strong sound (Kryter, 1985). While experiencing
TTS, the hearing threshold rises, and a sound must be stronger in order
to be heard. At least in terrestrial mammals, TTS can last from minutes
or hours to (in cases of strong TTS) days, can be limited to a
particular frequency range, and can be in varying degrees (i.e., a loss
of a certain number of dBs of sensitivity). For sound exposures at or
somewhat
[[Page 12557]]
above the TTS threshold, hearing sensitivity in both terrestrial and
marine mammals recovers rapidly after exposure to the noise ends. Few
data on sound levels and durations necessary to elicit mild TTS have
been obtained for marine mammals, and none of the published data
concern TTS elicited by exposure to multiple pulses of sound.
Marine mammal hearing plays a critical role in communication with
conspecifics and in interpretation of environmental cues for purposes
such as predator avoidance and prey capture. Depending on the degree
(elevation of threshold in dB), duration (i.e., recovery time), and
frequency range of TTS and the context in which it is experienced, TTS
can have effects on marine mammals ranging from discountable to
serious. For example, a marine mammal may be able to readily compensate
for a brief, relatively small amount of TTS in a non-critical frequency
range that takes place during a time when the animal is traveling
through the open ocean, where ambient noise is lower and there are not
as many competing sounds present. Alternatively, a larger amount and
longer duration of TTS sustained during a time when communication is
critical for successful mother/calf interactions could have more
serious impacts if it were in the same frequency band as the necessary
vocalizations and of a severity that it impeded communication. The fact
that animals exposed to levels and durations of sound that would be
expected to result in this physiological response would also be
expected to have behavioral responses of a comparatively more severe or
sustained nature is also notable and potentially of more importance
than the simple existence of a TTS.
Researchers have derived TTS information for odontocetes from
studies on the bottlenose dolphin and beluga. For the one harbor
porpoise tested, the received level of airgun sound that elicited onset
of TTS was lower (Lucke et al., 2009). If these results from a single
animal are representative, it is inappropriate to assume that onset of
TTS occurs at similar received levels in all odontocetes (cf. Southall
et al., 2007). Some cetaceans apparently can incur TTS at considerably
lower sound exposures than are necessary to elicit TTS in the beluga or
bottlenose dolphin.
For baleen whales, there are no data, direct or indirect, on levels
or properties of sound that are required to induce TTS. The frequencies
to which baleen whales are most sensitive are assumed to be lower than
those to which odontocetes are most sensitive, and natural background
noise levels at those low frequencies tend to be higher. As a result,
auditory thresholds of baleen whales within their frequency band of
best hearing are believed to be higher (less sensitive) than are those
of odontocetes at their best frequencies (Clark and Ellison, 2004),
meaning that baleen whales require sounds to be louder (i.e., higher dB
levels) than odontocetes in the frequency ranges at which each group
hears the best. From this, it is suspected that received levels causing
TTS onset may also be higher in baleen whales (Southall et al., 2007).
Since current NMFS practice assumes the same thresholds for the onset
of hearing impairment in both odontocetes and mysticetes, NMFS' onset
of TTS threshold is likely conservative for mysticetes. For this
proposed activity, COP expects no cases of TTS given the strong
likelihood that baleen whales would avoid the airguns before being
exposed to levels high enough for TTS to occur. The source levels of
the drillship are far lower than those of the airguns.
In pinnipeds, TTS thresholds associated with exposure to brief
pulses (single or multiple) of underwater sound have not been measured.
However, systematic TTS studies on captive pinnipeds have been
conducted (Bowles et al., 1999; Kastak et al., 1999, 2005, 2007;
Schusterman et al., 2000; Finneran et al., 2003; Southall et al.,
2007). Initial evidence from more prolonged (non-pulse) exposures
suggested that some pinnipeds (harbor seals in particular) incur TTS at
somewhat lower received levels than do small odontocetes exposed for
similar durations (Kastak et al., 1999, 2005; Ketten et al., 2001; cf.
Au et al., 2000). The TTS threshold for pulsed sounds has been
indirectly estimated as being an SEL of approximately 171 dB re 1
[mu]Pa\2\[middot]s (Southall et al., 2007) which would be equivalent to
a single pulse with a received level of approximately 181 to 186 dB re
1 [mu]Pa (rms), or a series of pulses for which the highest rms values
are a few dB lower. Corresponding values for California sea lions and
northern elephant seals are likely to be higher (Kastak et al., 2005).
For harbor seal, which is closely related to the ringed seal, TTS onset
apparently occurs at somewhat lower received energy levels than for
odonotocetes. The sound level necessary to cause TTS in pinnipeds
depends on exposure duration, as in other mammals; with longer
exposure, the level necessary to elicit TTS is reduced (Schusterman et
al., 2000; Kastak et al., 2005, 2007). For very short exposures (e.g.,
to a single sound pulse), the level necessary to cause TTS is very high
(Finneran et al., 2003). For pinnipeds exposed to in-air sounds,
auditory fatigue has been measured in response to single pulses and to
non-pulse noise (Southall et al., 2007), although high exposure levels
were required to induce TTS-onset (SEL: 129 dB re: 20
[mu]Pa2s; Bowles et al., unpub. data).
NMFS has established acoustic thresholds that identify the received
sound levels above which hearing impairment or other injury could
potentially occur, which are 180 and 190 dB re 1 [mu]Pa (rms) for
cetaceans and pinnipeds, respectively (NMFS 1995, 2000). The
established 180- and 190-dB re 1 [mu]Pa (rms) criteria are the received
levels above which, in the view of a panel of bioacoustics specialists
convened by NMFS before additional TTS measurements for marine mammals
became available, one could not be certain that there would be no
injurious effects, auditory or otherwise, to marine mammals. TTS is
considered by NMFS to be a type of Level B (non-injurious) harassment.
The 180- and 190-dB levels are shutdown criteria applicable to
cetaceans and pinnipeds, respectively, as specified by NMFS (2000) and
are used to establish exclusion zones (EZs), as appropriate.
Additionally, based on the summary provided here and the fact that
modeling indicates the source level of the drill rig will be below the
180 dB threshold (O'Neill et al., 2012), TTS is not expected to occur
in any marine mammal species that may occur in the proposed drilling
area since the source level will not reach levels thought to induce
even mild TTS. While the source level of the airgun is higher than the
190-dB threshold level, an animal would have to be in very close
proximity to be exposed to such levels. Additionally, the 180- and 190-
dB radii for the airgun are 0.6 mi (920 m) and 525 ft (160 m),
respectively, from the source. Because of the short duration that the
airguns will be used (no more than 4 hrs throughout the entire open-
water season) and mitigation and monitoring measures described later in
this document, hearing impairment is not anticipated.
PTS--When PTS occurs, there is physical damage to the sound
receptors in the ear. In some cases, there can be total or partial
deafness, whereas in other cases, the animal has an impaired ability to
hear sounds in specific frequency ranges (Kryter, 1985).
There is no specific evidence that exposure to underwater
industrial sound associated with oil exploration can cause PTS in any
marine mammal (see Southall et al., 2007). However,
[[Page 12558]]
given the possibility that mammals might incur TTS, there has been
further speculation about the possibility that some individuals
occurring very close to such activities might incur PTS (e.g.,
Richardson et al., 1995, p. 372ff; Gedamke et al., 2008). Single or
occasional occurrences of mild TTS are not indicative of permanent
auditory damage in terrestrial mammals. Relationships between TTS and
PTS thresholds have not been studied in marine mammals but are assumed
to be similar to those in humans and other terrestrial mammals
(Southall et al., 2007; Le Prell, in press). PTS might occur at a
received sound level at least several decibels above that inducing mild
TTS. Based on data from terrestrial mammals, a precautionary assumption
is that the PTS threshold for impulse sounds (such as airgun pulses as
received close to the source) is at least 6 dB higher than the TTS
threshold on a peak-pressure basis and probably greater than 6 dB
(Southall et al., 2007).
It is highly unlikely that marine mammals could receive sounds
strong enough (and over a sufficient duration) to cause PTS during the
proposed exploratory drilling program. As mentioned previously in this
document, the source levels of the drillship are not considered strong
enough to cause even slight TTS. Given the higher level of sound
necessary to cause PTS, it is even less likely that PTS could occur. In
fact, based on the modeled source levels for the drillship, the levels
immediately adjacent to the drillship may not be sufficient to induce
PTS, even if the animals remain in the immediate vicinity of the
activity. Modeled source levels for a jack-up drill rig suggest that
marine mammals located immediately adjacent to the rig would likely not
be exposed to received sound levels of a magnitude strong enough to
induce PTS, even if the animals remain in the immediate vicinity of the
proposed activity location for a prolonged period of time. Because the
source levels do not reach the thresholds of 190 dB currently used for
pinnipeds and 180 dB currently used for cetaceans, it is highly
unlikely that any type of hearing impairment, temporary or permanent,
would occur as a result of the exploration drilling activities.
Additionally, Southall et al. (2007) proposed that the thresholds for
injury of marine mammals exposed to ``discrete'' noise events (either
single or multiple exposures over a 24-hr period) are higher than the
180- and 190-dB re 1 [mu]Pa (rms) in-water threshold currently used by
NMFS. Table 1 in this document summarizes the sound pressure levels
(SPL) and SEL levels thought to cause auditory injury to cetaceans and
pinnipeds in-water. For more information, please refer to Southall et
al. (2007).
Table 1--Injury Criteria for Cetaceans and Pinnipeds Exposed to ``Discrete'' Noise Events (Either Single Pulses, Multiple Pulses, or Non-Pulses Within a
24-Hr Period; Cited in Southall et al., 2007). This Table Reflects Thresholds Based on Studies Reviewed in Southall et al. (2007) But Do Not Influence
the Estimation of Take in This Proposed IHA Notice as No Injury Is Anticipated To Occur
--------------------------------------------------------------------------------------------------------------------------------------------------------
Single pulses Multiple pulses Non pulses
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low-frequency cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sound pressure level.................. 230 dB re 1 [mu]Pa (peak) 230 dB re 1 [mu]Pa (peak) 230 dB re 1 [mu]Pa (peak) (flat)
(flat). (flat).
Sound exposure level.................. 198 dB re 1 [mu]Pa\2\-s (Mlf) 198 dB re 1 [mu]Pa\2\-s (Mlf) 215 dB re 1 [mu]Pa\2\-s (Mlf)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mid-frequency cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sound pressure level.................. 230 dB re 1 [mu]Pa (peak) 230 dB re 1 [mu]Pa (peak) 230 dB re 1 [mu]Pa (peak) (flat)
(flat). (flat).
Sound exposure level.................. 198 dB re 1 [mu]Pa\2\-s (Mlf) 198 dB re 1 [mu]Pa\2\-s (Mlf) 215 dB re 1 [mu]Pa\2\-s (Mlf)
--------------------------------------------------------------------------------------------------------------------------------------------------------
High-frequency cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sound pressure level.................. 230 dB re 1 [mu]Pa (peak) 230 dB re 1 [mu]Pa (peak) 230 dB re 1 [mu]Pa (peak) (flat)
(flat). (flat).
Sound exposure level.................. 198 dB re 1 [mu]Pa\2\-s (Mlf) 198 dB re 1 [mu]Pa\2\-s (Mlf) 215 dB re 1 [mu]Pa\2\-s (Mlf)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pinnipeds (in water)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sound pressure level.................. 218 dB re 1 [mu]Pa (peak) 218 dB re 1 [mu]Pa (peak) 218 dB re 1 [mu]Pa (peak) (flat)
(flat). (flat).
Sound exposure level.................. 186 dB re 1 [mu]Pa\2\-s (Mpw) 186 dB re 1 [mu]Pa\2\-s (Mpw) 203 dB re 1 [mu]Pa\2\-s (Mpw)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Non-auditory Physiological Effects--Non-auditory physiological
effects or injuries that theoretically might occur in marine mammals
exposed to strong underwater sound include stress, neurological
effects, bubble formation, and other types of organ or tissue damage
(Cox et al., 2006; Southall et al., 2007). Studies examining any such
effects are limited. If any such effects do occur, they probably would
be limited to unusual situations when animals might be exposed at close
range for unusually long periods. It is doubtful that any single marine
mammal would be exposed to strong sounds for sufficiently long that
significant physiological stress would develop.
Classic stress responses begin when an animal's central nervous
system perceives a potential threat to its homeostasis. That perception
triggers stress responses regardless of whether a stimulus actually
threatens the animal; the mere perception of a threat is sufficient to
trigger a stress response (Moberg, 2000; Sapolsky et al., 2005; Seyle,
1950). Once an animal's central nervous system perceives a threat, it
mounts a biological response or defense that consists of a combination
of the four general biological defense responses: behavioral responses;
autonomic nervous system responses; neuroendocrine responses; or immune
responses.
In the case of many stressors, an animal's first and most
economical (in terms of biotic costs) response is behavioral avoidance
of the potential stressor or avoidance of continued exposure to a
stressor. An animal's second line of defense to stressors involves the
sympathetic part of the autonomic nervous system and the classical
``fight or flight'' response, which includes the cardiovascular system,
the gastrointestinal system, the exocrine glands, and the adrenal
medulla to produce changes in heart
[[Page 12559]]
rate, blood pressure, and gastrointestinal activity that humans
commonly associate with ``stress.'' These responses have a relatively
short duration and may or may not have significant long-term effects on
an animal's welfare.
An animal's third line of defense to stressors involves its
neuroendocrine or sympathetic nervous systems; the system that has
received the most study has been the hypothalmus-pituitary-adrenal
system (also known as the HPA axis in mammals or the hypothalamus-
pituitary-interrenal axis in fish and some reptiles). Unlike stress
responses associated with the autonomic nervous system, virtually all
neuroendocrine functions that are affected by stress--including immune
competence, reproduction, metabolism, and behavior--are regulated by
pituitary hormones. Stress-induced changes in the secretion of
pituitary hormones have been implicated in failed reproduction (Moberg,
1987; Rivier, 1995), altered metabolism (Elasser et al., 2000), reduced
immune competence (Blecha, 2000), and behavioral disturbance. Increases
in the circulation of glucocorticosteroids (cortisol, corticosterone,
and aldosterone in marine mammals; see Romano et al., 2004) have been
equated with stress for many years.
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and distress is the biotic cost
of the response. During a stress response, an animal uses glycogen
stores that can be quickly replenished once the stress is alleviated.
In such circumstances, the cost of the stress response would not pose a
risk to the animal's welfare. However, when an animal does not have
sufficient energy reserves to satisfy the energetic costs of a stress
response, energy resources must be diverted from other biotic
functions, which impair those functions that experience the diversion.
For example, when mounting a stress response diverts energy away from
growth in young animals, those animals may experience stunted growth.
When mounting a stress response diverts energy from a fetus, an
animal's reproductive success and fitness will suffer. In these cases,
the animals will have entered a pre-pathological or pathological state
which is called ``distress'' (sensu Seyle, 1950) or ``allostatic
loading'' (sensu McEwen and Wingfield, 2003). This pathological state
will last until the animal replenishes its biotic reserves sufficient
to restore normal function. Note that these examples involved a long-
term (days or weeks) stress response exposure to stimuli.
Relationships between these physiological mechanisms, animal
behavior, and the costs of stress responses have also been documented
fairly well through controlled experiment; because this physiology
exists in every vertebrate that has been studied, it is not surprising
that stress responses and their costs have been documented in both
laboratory and free-living animals (for examples see, Holberton et al.,
1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004;
Lankford et al., 2005; Reneerkens et al., 2002; Thompson and Hamer,
2000). Although no information has been collected on the physiological
responses of marine mammals to anthropogenic sound exposure, studies of
other marine animals and terrestrial animals would lead us to expect
some marine mammals to experience physiological stress responses and,
perhaps, physiological responses that would be classified as
``distress'' upon exposure to anthropogenic sounds.
For example, Jansen (1998) reported on the relationship between
acoustic exposures and physiological responses that are indicative of
stress responses in humans (e.g., elevated respiration and increased
heart rates). Jones (1998) reported on reductions in human performance
when faced with acute, repetitive exposures to acoustic disturbance.
Trimper et al. (1998) reported on the physiological stress responses of
osprey to low-level aircraft noise while Krausman et al. (2004)
reported on the auditory and physiology stress responses of endangered
Sonoran pronghorn to military overflights. Smith et al. (2004a, 2004b)
identified noise-induced physiological transient stress responses in
hearing-specialist fish (i.e., goldfish) that accompanied short- and
long-term hearing losses. Welch and Welch (1970) reported physiological
and behavioral stress responses that accompanied damage to the inner
ears of fish and several mammals.
Hearing is one of the primary senses marine mammals use to gather
information about their environment and communicate with conspecifics.
Although empirical information on the relationship between sensory
impairment (TTS, PTS, and acoustic masking) on marine mammals remains
limited, it seems reasonable to assume that reducing an animal's
ability to gather information about its environment and to communicate
with other members of its species would be stressful for animals that
use hearing as their primary sensory mechanism. Therefore, we assume
that acoustic exposures sufficient to trigger onset PTS or TTS would be
accompanied by physiological stress responses because terrestrial
animals exhibit those responses under similar conditions (NRC, 2003).
More importantly, marine mammals might experience stress responses at
received levels lower than those necessary to trigger onset TTS. Based
on empirical studies of the time required to recover from stress
responses (Moberg, 2000), NMFS also assumes that stress responses could
persist beyond the time interval required for animals to recover from
TTS and might result in pathological and pre-pathological states that
would be as significant as behavioral responses to TTS. However, as
stated previously in this document, the source level of the drill rig
is not loud enough to induce PTS or even TTS.
Resonance effects (Gentry, 2002) and direct noise-induced bubble
formations (Crum et al., 2005) are implausible in the case of exposure
to an impulsive broadband source like an airgun array. If seismic
surveys disrupt diving patterns of deep-diving species, this might
result in bubble formation and a form of the bends, as speculated to
occur in beaked whales exposed to sonar. However, there is no specific
evidence of this upon exposure to airgun pulses. Additionally, no
beaked whale species occur in the proposed exploration drilling area.
In general, very little is known about the potential for strong,
anthropogenic underwater sounds to cause non-auditory physical effects
in marine mammals. Such effects, if they occur at all, would presumably
be limited to short distances and to activities that extend over a
prolonged period. The available data do not allow identification of a
specific exposure level above which non-auditory effects can be
expected (Southall et al., 2007) or any meaningful quantitative
predictions of the numbers (if any) of marine mammals that might be
affected in those ways. The low levels of continuous sound that will be
produced by the drillship are not expected to cause such effects.
Additionally, marine mammals that show behavioral avoidance of the
proposed activities, including most baleen whales, some odontocetes
(including belugas), and some pinnipeds, are especially unlikely to
incur auditory impairment or other physical effects.
Stranding and Mortality
Marine mammals close to underwater detonations of high explosives
can be killed or severely injured, and the auditory organs are
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995).
However, explosives are
[[Page 12560]]
no longer used for marine waters for commercial seismic surveys; they
have been replaced entirely by airguns or related non-explosive pulse
generators. Underwater sound from drilling, support activities, and
airgun arrays is less energetic and has slower rise times, and there is
no proof that they can cause serious injury, death, or stranding, even
in the case of large airgun arrays. However, the association of mass
strandings of beaked whales with naval exercises involving mid-
frequency active sonar, and, in one case, a Lamont-Doherty Earth
Observatory (L-DEO) seismic survey (Malakoff, 2002; Cox et al., 2006),
has raised the possibility that beaked whales exposed to strong pulsed
sounds may be especially susceptible to injury and/or behavioral
reactions that can lead to stranding (e.g., Hildebrand, 2005; Southall
et al., 2007).
Specific sound-related processes that lead to strandings and
mortality are not well documented, but may include:
(1) Swimming in avoidance of a sound into shallow water;
(2) A change in behavior (such as a change in diving behavior) that
might contribute to tissue damage, gas bubble formation, hypoxia,
cardiac arrhythmia, hypertensive hemorrhage or other forms of trauma;
(3) A physiological change, such as a vestibular response leading
to a behavioral change or stress-induced hemorrhagic diathesis, leading
in turn to tissue damage; and
(4) Tissue damage directly from sound exposure, such as through
acoustically-mediated bubble formation and growth or acoustic resonance
of tissues.
Some of these mechanisms are unlikely to apply in the case of
impulse sounds. However, there are indications that gas-bubble disease
(analogous to ``the bends''), induced in supersaturated tissue by a
behavioral response to acoustic exposure, could be a pathologic
mechanism for the strandings and mortality of some deep-diving
cetaceans exposed to sonar. However, the evidence for this remains
circumstantial and is associated with exposure to naval mid-frequency
sonar, not seismic surveys or exploratory drilling programs (Cox et
al., 2006; Southall et al., 2007).
Both seismic pulses and continuous drillship sounds are quite
different from mid-frequency sonar signals, and some mechanisms by
which sonar sounds have been hypothesized to affect beaked whales are
unlikely to apply to airgun pulses or drill rigs. Sounds produced by
airgun arrays are broadband impulses with most of the energy below 1
kHz, and the low-energy continuous sounds produced by drill rigs have
most of the energy between 20 and 1,000 Hz. Additionally, the non-
impulsive, continuous sounds produced by the jack-up rig proposed to be
used by COP does not have rapid rise times. Rise time is the
fluctuation in sound levels of the source. The type of sound that would
be produced during the proposed drilling program will be constant and
will not exhibit any sudden fluctuations or changes. Typical military
mid-frequency sonar emits non-impulse sounds at frequencies of 2-10
kHz, generally with a relatively narrow bandwidth at any one time. A
further difference between them is that naval exercises can involve
sound sources on more than one vessel. Thus, it is not appropriate to
assume that there is a direct connection between the effects of
military sonar and oil and gas industry operations on marine mammals.
However, evidence that sonar signals can, in special circumstances,
lead (at least indirectly) to physical damage and mortality (e.g.,
Balcomb and Claridge, 2001; NOAA and USN, 2001; Jepson et al., 2003;
Fern[aacute]ndez et al., 2004, 2005; Hildebrand, 2005; Cox et al.,
2006) suggests that caution is warranted when dealing with exposure of
marine mammals to any high-intensity ``pulsed'' sound.
There is no conclusive evidence of cetacean strandings or deaths at
sea as a result of exposure to seismic surveys, but a few cases of
strandings in the general area where a seismic survey was ongoing have
led to speculation concerning a possible link between seismic surveys
and strandings. Suggestions that there was a link between seismic
surveys and strandings of humpback whales in Brazil (Engel et al.,
2004) were not well founded (IAGC, 2004; IWC, 2007). In September 2002,
there was a stranding of two Cuvier's beaked whales in the Gulf of
California, Mexico, when the L-DEO vessel R/V Maurice Ewing was
operating a 20 airgun (8,490 in\3\) array in the general area. The link
between the stranding and the seismic surveys was inconclusive and not
based on any physical evidence (Hogarth, 2002; Yoder, 2002).
Nonetheless, the Gulf of California incident, plus the beaked whale
strandings near naval exercises involving use of mid-frequency sonar,
suggests a need for caution in conducting seismic surveys in areas
occupied by beaked whales until more is known about effects of seismic
surveys on those species (Hildebrand, 2005). No injuries of beaked
whales are anticipated during the proposed exploratory drilling program
because none occur in the proposed area.
Oil Spill Response Preparedness and Potential Impacts of an Oil Spill
As noted above, the specified activity involves the drilling of
exploratory wells and associated activities in the Chukchi Sea during
the 2012 open-water season. The impacts to marine mammals that are
reasonably expected to occur will be acoustic in nature. The likelihood
of a large or very large oil spill occurring during COP's proposed
exploratory drilling program is remote. A total of 35 exploration wells
have been drilled between 1982 and 2003 in the Chukchi and Beaufort
seas, and there have been no blowouts. In addition, no blowouts have
occurred from the approximately 98 exploration wells drilled within the
Alaskan OCS (MMS, 2007a). BOEM's Supplemental Environmental Impact
Statement for the Chukchi Sea Oil and Gas Lease Sale 193 (BOEM, 2011)
provides a discussion of the extremely low likelihood of an oil spill
occurring (available on the Internet at: http://www.boem.gov/About-BOEM/BOEM-Regions/Alaska-Region/Environment/Environmental-Analysis/OCS-EIS/EA-BOEMRE-2011-041.aspx). For more recent updates on occurrence
rates for offshore oil spills from drilling platforms, including spills
greater than or equal to 1,000 barrels (bbls) and greater than or equal
to 10,000 bbls, we refer to the BOEM-funded study of McMahon-Anders et
al. (2012). However, this study did not focus solely on the Alaskan
OCS. Another BOEM-directed study discusses most recent oil spill
occurrence estimators and their variability for the Beaufort and
Chukchi Seas for various sizes of spills as small as 50 bbls (Bercha,
2011). Bercha (2011) notes that because of the difference in oil spill
indicators between non-Arctic OCS areas and the Beaufort and Chukchi
Seas OCS areas, the non-Arctic areas are likely to result in a somewhat
higher oil spill occurrence probability than comparable developments in
the Chukchi or Beaufort Seas.
COP will have various measures and protocols in place that will be
implemented to prevent oil releases from the wellbore, such as:
Using information from previous wells in addition to
recent data collected from 3D seismic and shallow hazard surveys, where
applicable, to increase knowledge of the subsurface environment;
Using skilled personnel and providing them with project-
specific training. Implementing frequent drills to keep personnel
alert;
Implementation of visual and automated procedures for the
early detection of a spill:
[[Page 12561]]
[cir] The drilling operation will be monitored continuously by Pit-
Volume Totalizer equipment and visual monitoring of the mud circulating
system.
[cir] Alarms will be sounded if there is a significant volume
increase of drilling mud in the pits due to an influx into the
wellbore.
[cir] Multiple walk-through inspections of the rig are performed
every day by each crew to inspect and verify all control systems are
functioning properly.
[cir] Mobile Offshore Drilling Unit's (MODU) Central Control &
Radio Room monitors all safety aspects of the rig and is manned 24 hrs
per day by qualified rig personnel.
[cir] Established emergency shutdown philosophies will be
documented in the Contractor's Operations manuals and the crews will be
trained accordingly. An emergency shutdown can be initiated manually by
operators at the instrument/control panels or automatically under
certain conditions.
Maintaining a minimum of two barriers; the jack-up rig has
the capability of utilizing advanced well control barriers:
[cir] Surface blow out preventer (BOP) located on the rig in a
place that is easily accessible. This BOP can close in well on drill
pipe or open hole.
[cir] Thick walled high strength riser designed to contain full
well pressure.
[cir] Pre-Positioned Capping Device (PCD) will be installed above
the wellhead on the sea floor. The PCD can keep the well isolated with
pressure containment, even if the rig is moved off location. The PCD
can be triggered remotely from the drill rig or from support vessels.
Mechanical containment and recovery is COP's primary form of
response. Actual spill response decisions depend on safety
considerations, weather, and other environmental conditions. It is the
discretion of the Incident Commander and Unified Command to select any
sequence, response measure, or take as much time as necessary, to
employ an effective response. COP's spill response fleet is mobile and
capable of responding to incidents affecting open-water, nearshore, and
shoreline environments. Offshore spill response would be provided by
the following vessels:
Oil Spill Response Vessel (OSRV), the primary offshore oil
spill response platform, located within about 5.5 mi (9 km) of the
drilling rig;
Offshore Supply Vessel (OSV), a vessel of opportunity
response platform, located within about 5.5 mi (9 km) of the drilling
rig;
Four workboats, two are located on the OSRV and two on the
OSV; and
One Oil Spill Tanker (OST), with a storage capacity of at
least 520,000 barrels, also located within about 5.5 mi (9 km) from the
drilling rig.
Alaska Clean Seas personnel will be stationed on OSRV, OSV, and the
drill rig. OSRV is the primary spill response vessel; it will also be
used to support refueling of the jack-up rig. In the event of an
emergency, OSV will provide oil spill response and fast response craft
capability near the ware vessel. During non-emergency operations, OSV
will provide operational drill rig support, including standby support
during vessel refueling operations. From the standby locations, it will
take about 30 min for the vessels to arrive at the rig.
Spill response support for nearshore operations will be located
about 5.5 mi (9 km) from the drill rig location and approximately 5 mi
(8 km) offshore of Wainwright. Nearshore spill response operations are
provided by the following vessels:
One Oil Spill Response Barge (OSRB) and tug with a storage
capacity of 40,000 bbls;
Four workboats, located on the OSRB;
One large landing craft, located adjacent to the OSRB; and
Four 32-foot shallow draft landing craft located on the
large landing craft.
The OSRB and large landing craft are designed to carry and deploy a
majority of the nearshore and onshore spill response assets. In the
event of a spill, additional responders would be mobilized to man the
OSRB, large landing craft, and other support vessels. From 5 mi (8 km)
offshore of Wainwright it will take about 24 hrs for the OSRB to arrive
at the rig, assuming a travel speed of 5 knots and including
notification time. However, because this barge is equipped primarily
for nearshore response, it is unlikely to be needed offshore near the
rig.
Despite concluding that the risk of serious injury or mortality
from an oil spill in this case is extremely remote, NMFS has
nonetheless evaluated the potential effects of an oil spill on marine
mammals. While an oil spill is not a component of COP's specified
activity for which NMFS is proposing to authorize take, potential
impacts on marine mammals from an oil spill are discussed in more
detail below and will be addressed further in the Environmental
Assessment.
Potential Effects of Oil on Cetaceans
The specific effects an oil spill would have on cetaceans are not
well known. While mortality is unlikely, exposure to spilled oil could
lead to skin irritation, baleen fouling (which might reduce feeding
efficiency), respiratory distress from inhalation of hydrocarbon
vapors, consumption of some contaminated prey items, and temporary
displacement from contaminated feeding areas. Geraci and St. Aubin
(1990) summarize effects of oil on marine mammals, and Bratton et al.
(1993) provides a synthesis of knowledge of oil effects on bowhead
whales. The number of cetaceans that might be contacted by a spill
would depend on the size, timing, and duration of the spill and where
the oil is in relation to the animals. Whales may not avoid oil spills,
and some have been observed feeding within oil slicks (Goodale et al.,
1981). These topics are discussed in more detail next.
In the case of an oil spill occurring during migration periods,
disturbance of the migrating cetaceans from cleanup activities may have
more of an impact than the oil itself. Human activity associated with
cleanup efforts could deflect whales away from the path of the oil.
However, noise created from cleanup activities likely will be short
term and localized. In fact, whale avoidance of clean-up activities may
benefit whales by displacing them from the oil spill area.
There is no direct evidence that oil spills, including the much
studied Santa Barbara Channel and Exxon Valdez spills, have caused any
deaths of cetaceans (Geraci, 1990; Brownell, 1971; Harvey and Dahlheim,
1994). It is suspected that some individually identified killer whales
that disappeared from Prince William Sound during the time of the Exxon
Valdez spill were casualties of that spill. However, no clear cause and
effect relationship between the spill and the disappearance could be
established (Dahlheim and Matkin, 1994). The AT-1 pod of transient
killer whales that sometimes inhabits Prince William Sound has
continued to decline after the Exxon Valdez oil spill (EVOS). Matkin et
al. (2008) tracked the AB resident pod and the AT-1 transient group of
killer whales from 1984 to 2005. The results of their photographic
surveillance indicate a much higher than usual mortality rate for both
populations the year following the spill (33% for AB Pod and 41% for
AT-1 Group) and lower than average rates of increase in the 16 years
after the spill (annual increase of about 1.6% for AB Pod compared to
an annual increase of about 3.2% for other Alaska killer whale pods).
In killer whale pods, mortality rates are usually higher for non-
reproductive animals and very low for reproductive animals and
adolescents
[[Page 12562]]
(Olesiuk et al., 1990, 2005; Matkin et al., 2005). No effects on
humpback whales in Prince William Sound were evident after the EVOS
(von Ziegesar et al., 1994). There was some temporary displacement of
humpback whales out of Prince William Sound, but this could have been
caused by oil contamination, boat and aircraft disturbance,
displacement of food sources, or other causes.
Migrating gray whales were apparently not greatly affected by the
Santa Barbara spill of 1969. There appeared to be no relationship
between the spill and mortality of marine mammals. The higher than
usual counts of dead marine mammals recorded after the spill
represented increased survey effort and therefore cannot be
conclusively linked to the spill itself (Brownell, 1971; Geraci, 1990).
The conclusion was that whales were either able to detect the oil and
avoid it or were unaffected by it (Geraci, 1990).
(1) Oiling of External Surfaces
Whales rely on a layer of blubber for insulation, so oil would have
little if any effect on thermoregulation by whales. Effects of oiling
on cetacean skin appear to be minor and of little significance to the
animal's health (Geraci, 1990). Histological data and ultrastructural
studies by Geraci and St. Aubin (1990) showed that exposures of skin to
crude oil for up to 45 minutes in four species of toothed whales had no
effect. They switched to gasoline and applied the sponge up to 75
minutes. This produced transient damage to epidermal cells in whales.
Subtle changes were evident only at the cell level. In each case, the
skin damage healed within a week. They concluded that a cetacean's skin
is an effective barrier to the noxious substances in petroleum. These
substances normally damage skin by getting between cells and dissolving
protective lipids. In cetacean skin, however, tight intercellular
bridges, vital surface cells, and the extraordinary thickness of the
epidermis impeded the damage. The authors could not detect a change in
lipid concentration between and within cells after exposing skin from a
white-sided dolphin to gasoline for 16 hours in vitro.
Bratton et al. (1993) synthesized studies on the potential effects
of contaminants on bowhead whales. They concluded that no published
data proved oil fouling of the skin of any free-living whales, and
conclude that bowhead whales contacting fresh or weathered petroleum
are unlikely to suffer harm. Although oil is unlikely to adhere to
smooth skin, it may stick to rough areas on the surface (Henk and
Mullan, 1997). Haldiman et al. (1985) found the epidermal layer to be
as much as seven to eight times thicker than that found on most whales.
They also found that little or no crude oil adhered to preserved
bowhead skin that was dipped into oil up to three times, as long as a
water film stayed on the skin's surface. Oil adhered in small patches
to the surface and vibrissae (stiff, hairlike structures), once it made
enough contact with the skin. The amount of oil sticking to the
surrounding skin and epidermal depression appeared to be in proportion
to the number of exposures and the roughness of the skin's surface. It
can be assumed that if oil contacted the eyes, effects would be similar
to those observed in ringed seals; continued exposure of the eyes to
oil could cause permanent damage (St. Aubin, 1990).
(2) Ingestion
Whales could ingest oil if their food is contaminated, or oil could
also be absorbed through the respiratory tract. Some of the ingested
oil is voided in vomit or feces but some is absorbed and could cause
toxic effects (Geraci, 1990). When returned to clean water,
contaminated animals can depurate this internal oil (Engelhardt, 1978,
1982). Oil ingestion can decrease food assimilation of prey eaten (St.
Aubin, 1988). Cetaceans may swallow some oil-contaminated prey, but it
likely would be only a small part of their food. It is not known if
whales would leave a feeding area where prey was abundant following a
spill. Some zooplankton eaten by bowheads and gray whales consume oil
particles and bioaccumulation can result. Tissue studies by Geraci and
St. Aubin (1990) revealed low levels of naphthalene in the livers and
blubber of baleen whales. This result suggests that prey have low
concentrations in their tissues, or that baleen whales may be able to
metabolize and excrete certain petroleum hydrocarbons. Whales exposed
to an oil spill are unlikely to ingest enough oil to cause serious
internal damage (Geraci and St. Aubin, 1980, 1982) and this kind of
damage has not been reported (Geraci, 1990).
(3) Fouling of Baleen
Baleen itself is not damaged by exposure to oil and is resistant to
effects of oil (St. Aubin et al., 1984). Crude oil could coat the
baleen and reduce filtration efficiency; however, effects may be
temporary (Braithwaite, 1983; St. Aubin et al., 1984). If baleen is
coated in oil for long periods, it could cause the animal to be unable
to feed, which could lead to malnutrition or even death. Most of the
oil that would coat the baleen is removed after 30 min, and less than
5% would remain after 24 hr (Bratton et al., 1993). Effects of oiling
of the baleen on feeding efficiency appear to be minor (Geraci, 1990).
However, a study conducted by Lambertsen et al. (2005) concluded that
their results highlight the uncertainty about how rapidly oil would
depurate at the near zero temperatures in arctic waters and whether
baleen function would be restored after oiling.
(4) Avoidance
Some cetaceans can detect oil and sometimes avoid it, but others
enter and swim through slicks without apparent effects (Geraci, 1990;
Harvey and Dahlheim, 1994). Bottlenose dolphins in the Gulf of Mexico
apparently could detect and avoid slicks and mousse but did not avoid
light sheens on the surface (Smultea and Wursig, 1995). After the Regal
Sword spill in 1979, various species of baleen and toothed whales were
observed swimming and feeding in areas containing spilled oil southeast
of Cape Cod, MA (Goodale et al., 1981). For months following EVOS,
there were numerous observations of gray whales, harbor porpoises,
Dall's porpoises, and killer whales swimming through light-to-heavy
crude-oil sheens (Harvey and Dalheim, 1994, cited in Matkin et al.,
2008). However, if some of the animals avoid the area because of the
oil, then the effects of the oiling would be less severe on those
individuals.
(5) Factors Affecting the Severity of Effects
Effects of oil on cetaceans in open water are likely to be minimal,
but there could be effects on cetaceans where both the oil and the
whales are at least partly confined in leads or at ice edges (Geraci,
1990). In spring, bowhead and beluga whales migrate through leads in
the ice. At this time, the migration can be concentrated in narrow
corridors defined by the leads, thereby creating a greater risk to
animals caught in the spring lead system should oil enter the leads.
This situation would only occur if there were an oil spill late in the
season and COP could not complete cleanup efforts prior to ice covering
the area. The oil would likely then be trapped in the ice until it
began to thaw in the spring.
In fall, the migration route of bowheads can be close to shore
(Blackwell et al., 2009c). If fall migrants were moving through leads
in the pack ice or were concentrated in nearshore waters, some bowhead
whales might not be able to avoid oil slicks and could be
[[Page 12563]]
subject to prolonged contamination. However, the autumn migration
through the Chukchi Sea extends over several weeks, and some of the
whales travel along routes north or inland of the area, thereby
reducing the number of whales that could approach patches of spilled
oil. Additionally, vessel activity associated with spill cleanup
efforts may deflect whales traveling near the Devils Paw prospect in
the Chukchi Sea, thereby reducing the likelihood of contact with
spilled oil.
Bowhead and beluga whales overwinter in the Bering Sea (mainly from
November to March). In the summer, the majority of the bowhead whales
are found in the Canadian Beaufort Sea, although some have recently
been observed in the U.S. Beaufort and Chukchi Seas during the summer
months (June to August). Data from the Barrow-based boat surveys in
2009 (George and Sheffield, 2009) showed that bowheads were observed
almost continuously in the waters near Barrow, including feeding groups
in the Chukchi Sea at the beginning of July. The majority of belugas in
the Beaufort stock migrate into the Beaufort Sea in April or May,
although some whales may pass Point Barrow as early as late March and
as late as July (Braham et al., 1984; Ljungblad et al., 1984;
Richardson et al., 1995a). Therefore, a spill in summer would not be
expected to have major impacts on these species. Additionally, humpback
and fin whales are only sighted in the Chukchi Sea in small numbers in
the summer, as this is thought to be the extreme northern edge of their
range. Therefore, impacts to these species from an oil spill would be
extremely limited.
Potential Effects of Oil on Pinnipeds
Ice seals are present in open-water areas during summer and early
autumn. Externally oiled phocid seals often survive and become clean,
but heavily oiled seal pups and adults may die, depending on the extent
of oiling and characteristics of the oil. Prolonged exposure could
occur if fuel or crude oil was spilled in or reached nearshore waters,
was spilled in a lead used by seals, or was spilled under the ice when
seals have limited mobility (NMFS, 2000). Adult seals may suffer some
temporary adverse effects, such as eye and skin irritation, with
possible infection (MMS, 1996). Such effects may increase stress, which
could contribute to the death of some individuals. Ringed seals may
ingest oil-contaminated foods, but there is little evidence that oiled
seals will ingest enough oil to cause lethal internal effects. There is
a likelihood that newborn seal pups, if contacted by oil, would die
from oiling through loss of insulation and resulting hypothermia. These
potential effects are addressed in more detail in subsequent
paragraphs.
Reports of the effects of oil spills have shown that some mortality
of seals may have occurred as a result of oil fouling; however, large
scale mortality had not been observed prior to the EVOS (St. Aubin,
1990). Effects of oil on marine mammals were not well studied at most
spills because of lack of baseline data and/or the brevity of the post-
spill surveys. The largest documented impact of a spill, prior to EVOS,
was on young seals in January in the Gulf of St. Lawrence (St. Aubin,
1990). Brownell and Le Boeuf (1971) found no marked effects of oil from
the Santa Barbara oil spill on California sea lions or on the mortality
rates of newborn pups.
Intensive and long-term studies were conducted after the EVOS in
Alaska. There may have been a long-term decline of 36% in numbers of
molting harbor seals at oiled haul-out sites in Prince William Sound
following EVOS (Frost et al., 1994a). However, in a reanalysis of those
data and additional years of surveys, along with an examination of
assumptions and biases associated with the original data, Hoover-Miller
et al. (2001) concluded that the EVOS effect had been overestimated.
The decline in attendance at some oiled sites was more likely a
continuation of the general decline in harbor seal abundance in Prince
William Sound documented since 1984 (Frost et al., 1999) rather than a
result of EVOS. The results from Hoover-Miller et al. (2001) indicate
that the effects of EVOS were largely indistinguishable from natural
decline by 1992. However, while Frost et al. (2004) concluded that
there was no evidence that seals were displaced from oiled sites, they
did find that aerial counts indicated 26% fewer pups were produced at
oiled locations in 1989 than would have been expected without the oil
spill. Harbor seal pup mortality at oiled beaches was 23% to 26%, which
may have been higher than natural mortality, although no baseline data
for pup mortality existed prior to EVOS (Frost et al., 1994a). There
was no conclusive evidence of spill effects on Steller sea lions
(Calkins et al., 1994). Oil did not persist on sea lions themselves (as
it did on harbor seals), nor did it persist on sea lion haul-out sites
and rookeries (Calkins et al., 1994). Sea lion rookeries and haul out
sites, unlike those used by harbor seals, have steep sides and are
subject to high wave energy (Calkins et al., 1994).
(1) Oiling of External Surfaces
Adult seals rely on a layer of blubber for insulation, and oiling
of the external surface does not appear to have adverse
thermoregulatory effects (Kooyman et al., 1976, 1977; St. Aubin, 1990).
Contact with oil on the external surfaces can potentially cause
increased stress and irritation of the eyes of ringed seals (Geraci and
Smith, 1976; St. Aubin, 1990). These effects seemed to be temporary and
reversible, but continued exposure of eyes to oil could cause permanent
damage (St. Aubin, 1990). Corneal ulcers and abrasions, conjunctivitis,
and swollen nictitating membranes were observed in captive ringed seals
placed in crude oil-covered water (Geraci and Smith, 1976) and in seals
in the Antarctic after an oil spill (Lillie, 1954).
Newborn seal pups rely on their fur for insulation. Newborn ringed
seal pups in lairs on the ice could be contaminated through contact
with oiled mothers. There is the potential that newborn ringed seal
pups that were contaminated with oil could die from hypothermia.
However, COP's activities will not occur during pupping season or when
lairs are built.
(2) Ingestion
Marine mammals can ingest oil if their food is contaminated. Oil
can also be absorbed through the respiratory tract (Geraci and Smith,
1976; Engelhardt et al., 1977). Some of the ingested oil is voided in
vomit or feces but some is absorbed and could cause toxic effects
(Engelhardt, 1981). When returned to clean water, contaminated animals
can depurate this internal oil (Engelhardt, 1978, 1982, 1985). In
addition, seals exposed to an oil spill are unlikely to ingest enough
oil to cause serious internal damage (Geraci and St. Aubin, 1980,
1982).
(3) Avoidance and Behavioral Effects
Although seals may have the capability to detect and avoid oil,
they apparently do so only to a limited extent (St. Aubin, 1990). Seals
may abandon the area of an oil spill because of human disturbance
associated with cleanup efforts, but they are most likely to remain in
the area of the spill. One notable behavioral reaction to oiling is
that oiled seals are reluctant to enter the water, even when intense
cleanup activities are conducted nearby (St. Aubin, 1990; Frost et al.,
1994b, 2004).
(4) Factors Affecting the Severity of Effects
Seals that are under natural stress, such as lack of food or a
heavy infestation by parasites, could
[[Page 12564]]
potentially die because of the additional stress of oiling (Geraci and
Smith, 1976; St. Aubin, 1990; Spraker et al., 1994). Female seals that
are nursing young would be under natural stress, as would molting
seals. In both cases, the seals would have reduced food stores and may
be less resistant to effects of oil than seals that are not under some
type of natural stress. Seals that are not under natural stress (e.g.,
fasting, molting) would be more likely to survive oiling.
In general, seals do not exhibit large behavioral or physiological
reactions to limited surface oiling or incidental exposure to
contaminated food or vapors (St. Aubin, 1990; Williams et al., 1994).
Effects could be severe if seals surface in heavy oil slicks in leads
or if oil accumulates near haul-out sites (St. Aubin, 1990). An oil
spill in open-water is less likely to impact seals.
Potential Effects Conclusion
The potential effects to marine mammals described in this section
of the document do not take into consideration the proposed monitoring
and mitigation measures described later in this document (see the
``Proposed Mitigation'' and ``Proposed Monitoring and Reporting''
sections).
Anticipated Effects on Marine Mammal Habitat
The primary potential impacts to marine mammals and other marine
species are associated with elevated sound levels produced by the
exploratory drilling program (i.e. the drill rig and the airguns).
However, other potential impacts are also possible to the surrounding
habitat from physical disturbance, discharges, and an oil spill (should
one occur). This section describes the potential impacts to marine
mammal habitat from the specified activity. Because the marine mammals
in the area feed on fish and/or invertebrates there is also information
on the species typically preyed upon by the marine mammals in the area.
Common Marine Mammal Prey in the Area
All of the marine mammal species that may occur in the proposed
project area prey on either marine fish or invertebrates. The ringed
seal feeds on fish and a variety of benthic species, including crabs
and shrimp. Bearded seals feed mainly on benthic organisms, primarily
crabs, shrimp, and clams. Spotted seals feed on pelagic and demersal
fish, as well as shrimp and cephalopods. They are known to feed on a
variety of fish including herring, capelin, sand lance, Arctic cod,
saffron cod, and sculpins. Ribbon seals feed primarily on pelagic fish
and invertebrates, such as shrimp, crabs, squid, octopus, cod, sculpin,
pollack, and capelin. Juveniles feed mostly on krill and shrimp.
Bowhead whales feed in the eastern Beaufort Sea during summer and
early autumn but continue feeding to varying degrees while on their
migration through the central and western Beaufort Sea in the late
summer and fall (Richardson and Thomson [eds.], 2002). Aerial surveys
in recent years have sighted bowhead whales feeding in Camden Bay on
their westward migration through the Beaufort Sea. When feeding in
relatively shallow areas, bowheads feed throughout the water column.
However, feeding is concentrated at depths where zooplankton is
concentrated (Wursig et al., 1984, 1989; Richardson [ed.], 1987;
Griffiths et al., 2002). Lowry and Sheffield (2002) found that copepods
and euphausiids were the most common prey found in stomach samples from
bowhead whales harvested in the Kaktovik area from 1979 to 2000. Areas
to the east of Barter Island in the Beaufort Sea appear to be used
regularly for feeding as bowhead whales migrate slowly westward across
the Beaufort Sea (Thomson and Richardson, 1987; Richardson and Thomson
[eds.], 2002). However, in some years, sizable groups of bowhead whales
have been seen feeding as far west as the waters just east of Point
Barrow (which is more than 200 mi [322 km] east of COP's proposed drill
sites in the Chukchi Sea) near the Plover Islands (Braham et al., 1984;
Ljungblad et al., 1985; Landino et al., 1994). The situation in
September-October 1997 was unusual in that bowheads fed widely across
the Alaskan Beaufort Sea, including higher numbers in the area east of
Barrow than reported in any previous year (S. Treacy and D. Hansen,
MMS, pers. comm.). However, by the time most bowhead whales reach the
Chukchi Sea (October), they will likely no longer be feeding, or if it
occurs it will be very limited. The location near Point Barrow is
currently under intensive study as part of the BOWFEST program
(BOWFEST, 2011).
Beluga whales feed on a variety of fish, shrimp, squid, and octopus
(Burns and Seaman, 1985). Like several of the other species in the
area, harbor porpoise feed on demersal and benthic species, mainly
schooling fish and cephalopods. Killer whales from resident stocks
primarily feed on salmon while killer whales from transient stocks feed
on other marine mammals, such as harbor seals, harbor porpoises, gray
whale calves and other pinniped and cetacean species.
Gray whales are primarily bottom feeders, and benthic amphipods and
isopods form the majority of their summer diet, at least in the main
summering areas west of Alaska (Oliver et al., 1983; Oliver and
Slattery, 1985). Farther south, gray whales have also been observed
feeding around kelp beds, presumably on mysid crustaceans, and on
pelagic prey such as small schooling fish and crab larvae (Hatler and
Darling, 1974). Based on data collected from recent Aerial Survey of
Arctic Marine Mammals (ASAMM, formerly referred to as BWASP for the
Beaufort Sea or COMIDA for the Chukchi Sea) flights (Clarke and
Ferguson, 2010; Clarke et al., in prep.; Clarke et al., 2011; Clarke et
al., 2012) three primary feeding grounds have been identified as
currently used by gray whales in the Chukchi Sea: (1) Between Point
Barrow and Icy Cape within approximately 56 mi (90 km) of shore; (2)
nearshore from south of Point Hope to east of Cape Lisburne; and (3) in
the south-central Chukchi Sea. These latter two locations are located
substantial distances from COP's operating area. With the exception of
vessel transits, the first feeding area is also located outside of
COP's drilling area.
Three other baleen whale species may occur in the proposed project
area, although likely in very small numbers: minke, humpback, and fin
whales. Minke whales opportunistically feed on crustaceans (e.g.,
krill), plankton (e.g., copepods), and small schooling fish (e.g.,
anchovies, dogfish, capelin, coal fish, cod, eels, herring, mackerel,
salmon, sand lance, saury, and wolfish) (Reeves et al., 2002). Fin
whales tend to feed in northern latitudes in the summer months on
plankton and shoaling pelagic fish (Jonsgard, 1966a,b). Like many of
the other species in the area, humpback whales primarily feed on
euphausiids, copepods, and small schooling fish (e.g., herring,
capelin, and sand lance) (Reeves et al., 2002). However, the primary
feeding grounds for these species do not occur in the northern Chukchi
Sea.
Two kinds of fish inhabit marine waters in the study area: (1) true
marine fish that spend all of their lives in salt water, and (2)
anadromous species that reproduce in fresh water and spend parts of
their life cycles in salt water.
Most arctic marine fish species are small, benthic forms that do
not feed high in the water column. The majority of these species are
circumpolar and are found in habitats ranging from deep offshore water
to water as shallow as
[[Page 12565]]
16.4-33 ft (5-10 m; Fechhelm et al., 1995). The most important pelagic
species, and the only abundant pelagic species, is the Arctic cod. The
Arctic cod is a major vector for the transfer of energy from lower to
higher trophic levels (Bradstreet et al., 1986). In summer, Arctic cod
can form very large schools in both nearshore and offshore waters
(Craig et al., 1982; Bradstreet et al., 1986). Locations and areas
frequented by large schools of Arctic cod cannot be predicted but can
be almost anywhere. The Arctic cod is a major food source for beluga
whales, ringed seals, and numerous species of seabirds (Frost and
Lowry, 1984; Bradstreet et al., 1986).
Anadromous Dolly Varden char and some species of whitefish winter
in rivers and lakes, migrate to the sea in spring and summer, and
return to fresh water in autumn. Anadromous fish form the basis of
subsistence, commercial, and small regional sport fisheries. Dolly
Varden char migrate to the sea from May through mid-June (Johnson,
1980) and spend about 1.5-2.5 months there (Craig, 1989). They return
to rivers beginning in late July or early August with the peak return
migration occurring between mid-August and early September (Johnson,
1980). At sea, most anadromous corregonids (whitefish) remain in
nearshore waters within several kilometers of shore (Craig, 1984,
1989). They are often termed ``amphidromous'' fish in that they make
repeated annual migrations into marine waters to feed, returning each
fall to overwinter in fresh water.
Benthic organisms are defined as bottom dwelling creatures.
Infaunal organisms are benthic organisms that live within the substrate
and are often sedentary or sessile (bivalves, polychaetes). Epibenthic
organisms live on or near the bottom surface sediments and are mobile
(amphipods, isopods, mysids, and some polychaetes). The northeastern
Chukchi Sea supports a higher biomass of benthic organisms than do
surrounding areas (Grebmeier and Dunton, 2000). Some benthic-feeding
marine mammals, such as walruses and gray whales, take advantage of the
abundant food resources and congregate in these highly productive
areas. Harold and Hanna Shoals are two known highly productive areas in
the Chukchi Sea rich with benthic animals.
Many of the nearshore benthic marine invertebrates of the Arctic
are circumpolar and are found over a wide range of water depths (Carey
et al., 1975). Species identified include polychaetes (Spio filicornis,
Chaetozone setosa, Eteone longa), bivalves (Cryrtodaria kurriana,
Nucula tenuis, Liocyma fluctuosa), an isopod (Saduria entomon), and
amphipods (Pontoporeia femorata, P. affinis). Additionally, kelp beds
occur in at least two areas in the nearshore areas of the Chukchi Sea
(Mohr et al., 1957; Phillips et al., 1982; Phillips and Reiss, 1985),
but they are located within about 15.5 mi (25 km) of the coast, which
is much closer nearshore than COP's proposed activities.
Potential Impacts From Seafloor Disturbance on Marine Mammal Habitat
There is a possibility of seafloor disturbance or increased
turbidity in the vicinity of the drill sites. Seafloor disturbance
could occur with bottom founding of the drill rig legs and anchoring
system and also with the anchoring systems of support vessels. These
activities could lead to direct effects on bottom fauna, through either
displacement or mortality. Increase in suspended sediments from
seafloor disturbance also has the potential to indirectly affect bottom
fauna and fish. The amount and duration of disturbed or turbid
conditions will depend on sediment material.
Placement of the drill rig onto the seabed will include firm
establishment of its legs onto the seafloor. No anchors are required to
be deployed for stabilization of the rig. Displacement or mortality of
bottom organisms will likely occur in the area covered by the spud can
of the legs. The area of seabed that will be covered by these spud cans
is about 2,165 ft \2\ (200 m \2\) per spud, which is a total of 6,500
ft \2\ (600 m \2\) for three legs or 8,660 ft \2\ (800 m\2\) for four
legs. The mean abundance of benthic organisms in the Klondike area was
about 800 individuals/m \2\ (Blanchard et al., 2010) and consisted
mostly of polychaete worms and mollusks. The drill rig is a temporary
structure that will be removed at the end of the field season. Because
of the placement of the spud cans, benthic organisms are expected to
decolonize the relatively small disturbed patches from adjacent areas.
Impacts to marine mammals from such disturbance are anticipated to be
inconsequential.
Placement and demobilization of the drill rig can lead to an
increase in suspended sediment in the water column, with the potential
to affect zooplankton, including fish eggs and larvae. The magnitude of
any impact strongly depends on the concentration of suspended
sediments, the type of sediment, the duration of exposure, and also of
the natural turbidity in the area. Fish eggs and larvae have been found
to exhibit greater sensitivity to suspended sediments (Wilber and
Clarke, 2001) and other stresses than adult fish, which is thought to
be related to their relative lack of motility (Auld and Schubel, 1978).
Sedimentation could potentially affect fish by causing egg morbidity of
demersal fish feeding near or on the ocean floor (Wilber and Clarke,
2001). However, the increase in suspended sediments from drill rig
placement, demobilization and anchor handling is very limited,
localized and temporary, and will likely be indistinguishable from
natural variations in turbidity and sedimentation. No impacts on
zooplankton are therefore expected considering the high inter-annual
variability in abundance and biomass in the Devils Paw Prospect,
influenced by timing of sea ice melt, water temperatures, northward
transport of water masses, and nutrients and chlorophyll (Hopcroft et
al., 2011).
Benthic organisms inhabiting the Devils Paw Prospect will likely be
displaced or smothered. However, due to the limited area and duration
of the proposed drilling program and because the area is mainly
characterized as a pelagic system (Day et al., 2012) with a low density
of benthic feeding marine mammals, the limited loss or modification of
habitat is not expected to result in impacts to marine mammals or their
populations. Less than 0.0000001 percent of the fish habitat in the
Lease Sale 193 area would be directly affected by the bottom founding
of the drill rig legs and anchoring.
Potential Impacts from Sound Generation
With regard to fish as a prey source for odontocetes and seals,
fish are known to hear and react to sounds and to use sound to
communicate (Tavolga et al., 1981) and possibly avoid predators (Wilson
and Dill, 2002). Experiments have shown that fish can sense both the
strength and direction of sound (Hawkins, 1981). Primary factors
determining whether a fish can sense a sound signal, and potentially
react to it, are the frequency of the signal and the strength of the
signal in relation to the natural background noise level.
Fishes produce sounds that are associated with behaviors that
include territoriality, mate search, courtship, and aggression. It has
also been speculated that sound production may provide the means for
long distance communication and communication under poor underwater
visibility conditions (Zelick et al., 1999), although the fact that
fish communicate at low-frequency sound levels where the masking
effects of ambient noise are naturally highest suggests that very long
[[Page 12566]]
distance communication would rarely be possible. Fishes have evolved a
diversity of sound generating organs and acoustic signals of various
temporal and spectral contents. Fish sounds vary in structure,
depending on the mechanism used to produce them (Hawkins, 1993).
Generally, fish sounds are predominantly composed of low frequencies
(less than 3 kHz).
Since objects in the water scatter sound, fish are able to detect
these objects through monitoring the ambient noise. Therefore, fish are
probably able to detect prey, predators, conspecifics, and physical
features by listening to environmental sounds (Hawkins, 1981). There
are two sensory systems that enable fish to monitor the vibration-based
information of their surroundings. The two sensory systems, the inner
ear and the lateral line, constitute the acoustico-lateralis system.
Although the hearing sensitivities of very few fish species have
been studied to date, it is becoming obvious that the intra- and inter-
specific variability is considerable (Coombs, 1981). Nedwell et al.
(2004) compiled and published available fish audiogram information. A
noninvasive electrophysiological recording method known as auditory
brainstem response is now commonly used in the production of fish
audiograms (Yan, 2004). Generally, most fish have their best hearing in
the low-frequency range (i.e., less than 1 kHz). Even though some fish
are able to detect sounds in the ultrasonic frequency range, the
thresholds at these higher frequencies tend to be considerably higher
than those at the lower end of the auditory frequency range.
Literature relating to the impacts of sound on marine fish species
can be divided into the following categories: (1) Pathological effects;
(2) physiological effects; and (3) behavioral effects. Pathological
effects include lethal and sub-lethal physical damage to fish;
physiological effects include primary and secondary stress responses;
and behavioral effects include changes in exhibited behaviors of fish.
Behavioral changes might be a direct reaction to a detected sound or a
result of the anthropogenic sound masking natural sounds that the fish
normally detect and to which they respond. The three types of effects
are often interrelated in complex ways. For example, some physiological
and behavioral effects could potentially lead to the ultimate
pathological effect of mortality. Hastings and Popper (2005) reviewed
what is known about the effects of sound on fishes and identified
studies needed to address areas of uncertainty relative to measurement
of sound and the responses of fishes. Popper et al. (2003/2004) also
published a paper that reviews the effects of anthropogenic sound on
the behavior and physiology of fishes.
Potential effects of exposure to continuous sound on marine fish
include TTS, physical damage to the ear region, physiological stress
responses, and behavioral responses such as startle response, alarm
response, avoidance, and perhaps lack of response due to masking of
acoustic cues. Most of these effects appear to be either temporary or
intermittent and therefore probably do not significantly impact the
fish at a population level. The studies that resulted in physical
damage to the fish ears used noise exposure levels and durations that
were far more extreme than would be encountered under conditions
similar to those expected during COP's proposed exploratory drilling
activities.
The level of sound at which a fish will react or alter its behavior
is usually well above the detection level. Fish have been found to
react to sounds when the sound level increased to about 20 dB above the
detection level of 120 dB (Ona, 1988); however, the response threshold
can depend on the time of year and the fish's physiological condition
(Engas et al., 1993). In general, fish react more strongly to pulses of
sound rather than a continuous signal (Blaxter et al., 1981), such as
the type of sound that will be produced by the drillship, and a quicker
alarm response is elicited when the sound signal intensity rises
rapidly compared to sound rising more slowly to the same level.
Investigations of fish behavior in relation to vessel noise (Olsen
et al., 1983; Ona, 1988; Ona and Godo, 1990) have shown that fish react
when the sound from the engines and propeller exceeds a certain level.
Avoidance reactions have been observed in fish such as cod and herring
when vessels approached close enough that received sound levels are 110
dB to 130 dB (Nakken, 1992; Olsen, 1979; Ona and Godo, 1990; Ona and
Toresen, 1988). However, other researchers have found that fish such as
polar cod, herring, and capeline are often attracted to vessels
(apparently by the noise) and swim toward the vessel (Rostad et al.,
2006). Typical sound source levels of vessel noise in the audible range
for fish are 150 dB to 170 dB (Richardson et al., 1995a). (Based on
models, the 160 dB radius for the jack-up rig would extend
approximately 33 ft [10 m] approximately 0.4 mi [710 m] when a support
vessel is in DP mode next to the drill rig; therefore, fish would need
to be in close proximity to the drill rig for the noise to be audible).
In calm weather, ambient noise levels in audible parts of the spectrum
lie between 60 dB to 100 dB.
Sound will also occur in the marine environment from the various
support vessels. Reported source levels for vessels during ice-
management have ranged from 175 dB to 185 dB (Brewer et al., 1993, Hall
et al., 1994). However, ice management activities are not expected to
be necessary throughout most of the drilling season, so impacts from
that activity would occur less frequently than sound from the drill
rig. Sounds generated by drilling and ice-management are generally low
frequency and within the frequency range detectable by most fish.
COP also proposes to conduct seismic surveys with an airgun array
for a short period of time during the drilling season (a total of
approximately 2-4 hours over the course of the entire proposed drilling
program). Airguns produce impulsive sounds as opposed to continuous
sounds at the source. Short, sharp sounds can cause overt or subtle
changes in fish behavior. Chapman and Hawkins (1969) tested the
reactions of whiting (hake) in the field to an airgun. When the airgun
was fired, the fish dove from 82 to 180 ft (25 to 55 m) depth and
formed a compact layer. The whiting dove when received sound levels
were higher than 178 dB re 1 [micro]Pa (Pearson et al., 1992).
Pearson et al. (1992) conducted a controlled experiment to
determine effects of strong noise pulses on several species of rockfish
off the California coast. They used an airgun with a source level of
223 dB re 1 [micro]Pa. They noted:
Startle responses at received levels of 200-205 dB re 1
[micro]Pa and above for two sensitive species, but not for two other
species exposed to levels up to 207 dB;
Alarm responses at 177-180 dB for the two sensitive
species, and at 186 to 199 dB for other species;
An overall threshold for the above behavioral response at
about 180 dB;
An extrapolated threshold of about 161 dB for subtle
changes in the behavior of rockfish; and
A return to pre-exposure behaviors within the 20-60 minute
exposure period.
In summary, fish often react to sounds, especially strong and/or
intermittent sounds of low frequency. Sound pulses at received levels
of 160 dB re 1 [micro]Pa may cause subtle changes in behavior. Pulses
at levels of 180 dB may cause noticeable changes in behavior (Chapman
and Hawkins, 1969;
[[Page 12567]]
Pearson et al., 1992; Skalski et al., 1992). It also appears that fish
often habituate to repeated strong sounds rather rapidly, on time
scales of minutes to an hour. However, the habituation does not endure,
and resumption of the strong sound source may again elicit disturbance
responses from the same fish. Underwater sound levels from the drill
rig and other vessels produce sounds lower than the response threshold
reported by Pearson et al. (1992), and are not likely to result in
major effects to fish near the proposed drill sites.
Based on a sound level of approximately 140 dB, there may be some
avoidance by fish of the area near the jack-up while drilling, around
ice management vessels in transit and during ice management, and around
other support and supply vessels when underway. Any reactions by fish
to these sounds will last only minutes (Mitson and Knudsen, 2003; Ona
et al., 2007) longer than the vessel is operating at that location or
the drillship is drilling. Any potential reactions by fish would be
limited to a relatively small area within about 33 ft (10 m) of the
drill rig during drilling. Avoidance by some fish or fish species could
occur within portions of this area. No important spawning habitats are
known to occur at or near the drilling locations.
Some of the fish species found in the Arctic are prey sources for
odontocetes and pinnipeds. A reaction by fish to sounds produced by
COP's proposed operations would only be relevant to marine mammals if
it caused concentrations of fish to vacate the area. Pressure changes
of sufficient magnitude to cause that type of reaction would probably
occur only very close to the sound source, if any would occur at all
due to the low energy sounds produced by the majority of equipment
proposed for use. Impacts on fish behavior are predicted to be
inconsequential. Thus, feeding odontocetes and pinnipeds would not be
adversely affected by this minimal loss or scattering, if any, which is
not expected to result in reduced prey abundance.
Some mysticetes, including bowhead whales, feed on concentrations
of zooplankton. Bowhead whales primarily feed off Point Barrow in
September and October. Reactions of zooplankton to sound are, for the
most part, not known. Their ability to move significant distances is
limited or nil, depending on the type of zooplankton. A reaction by
zooplankton to sounds produced by the exploratory drilling program
would only be relevant to whales if it caused concentrations of
zooplankton to scatter. Pressure changes of sufficient magnitude to
cause that type of reaction would probably occur only very close to the
sound source, if any would occur at all due to the low energy sounds
produced by the drillship. However, Barrow is located approximately 200
mi (322 km) east of COP's Devils Paw prospect. Impacts on zooplankton
behavior are predicted to be inconsequential. Thus, bowhead whales
feeding off Point Barrow would not be adversely affected.
Gray whales are bottom feeders and suck sediment and the benthic
amphipods that are their prey from the seafloor. The species primary
feeding habitats are in the northern Bering Sea and Chukchi Sea
(Nerini, 1984; Moore et al., 1986; Weller et al., 1999). As noted
earlier in this document, most gray whale feeding locations in the
Chukchi Sea are located closer to shore. Several of the primary feeding
grounds are located much further south in the Chukchi Sea than COP's
proposed activity area. Additionally, Yazvenko et al. (2007) studied
the impacts of seismic surveys off Sakhalin Island, Russia, on feeding
gray whales and found that the seismic activity had no measurable
effect on bottom feeding gray whales in the area.
Potential Impacts From Drill Cuttings
Discharging drill cuttings or other liquid waste streams generated
by the drilling vessel could potentially affect marine mammal habitat.
Toxins could persist in the water column, which could have an impact on
marine mammal prey species. However, despite a considerable amount of
investment in research on exposures of marine mammals to
organochlorines or other toxins, there have been no marine mammal
deaths in the wild that can be conclusively linked to the direct
exposure to such substances (O'Shea, 1999).
Drilling muds and cuttings discharged to the seafloor can lead to
localized increased turbidity and increase in background concentrations
of barium and occasionally other metals in sediments and may affect
lower trophic organisms. Drilling muds are composed primarily of
bentonite (clay), and the toxicity is therefore low. Heavy metals in
the mud may be absorbed by benthic organisms, but studies have shown
that heavy metals do not bio-magnify in marine food webs (Neff et al.,
1989). There have been no field monitoring studies of effects of water-
based muds and cuttings discharges on biological communities of the
Alaskan Chukchi Sea and only a few in the development area of the
Alaskan Beaufort Sea (Neff et al., 2010). However, the results of these
studies are consistent with the results of many more comprehensive
microcosm and ecological investigations near cuttings discharge sites
in cold-water environments of the North Sea, the Barents Sea, off
Sakhalin Island in the Russian Far East, and in the Canadian Beaufort
Sea off the Mackenzie River (Neff et al., 2010). All the studies show
that water-based muds and cuttings discharges have no, or minimal and
very short-lived effects on zooplankton communities. This might, in
part, be due to the large inter-annual differences observed in the
planktonic communities. In the Chukchi Sea the inter-annual variability
of zooplankton biomass and community structure is influenced by
differences in ice melt timing, water temperatures, and the northward
rate of transport of water masses, and nutrients and chlorophyll
(Hopcroft et al., 2011). Effects on benthic communities are nearly
always restricted to a zone within about 328 to 492 ft (100 to 150 m)
of the discharge, where cuttings accumulations are greatest.
Discharges and drill cuttings could impact fish by displacing them
from the affected area. Additionally, sedimentation could impact fish,
as demersal fish eggs could be smothered if discharges occur in a
spawning area during the period of egg production. However, this is
unlikely in deeper offshore locations, and no specific demersal fish
spawning locations have been identified at the Devils Paw well
locations. The most abundant and trophically important marine fish, the
Arctic cod, spawns with planktonic eggs and larvae under the sea ice
during winter and will therefore have little exposure to discharges.
Based on this information, drilling muds and cutting wastes are not
anticipated to have long-term impacts to marine mammals or their prey.
Potential Impacts From Drill Rig Presence
The horizontal dimensions of the jack-up rig will be approximately
230 x 225 ft (70 x 68 m). Maximum dimension of one leg spud can, which
is the part on the seafloor, is about 60 ft (18 m). The dimensions of
the drill rig (less than one football field on either side) are not
significant enough to cause a large-scale diversion from the animals'
normal swim and migratory paths. Additionally, the eastward spring
bowhead whale migration will occur prior to the beginning of COP's
proposed exploratory drilling program. Moreover, any deflection of
bowhead whales or other marine mammal species
[[Page 12568]]
due to the physical presence of the drillship or its support vessels
would be very minor. The drill rig's physical footprint is small
relative to the size of the geographic region it will occupy and will
likely not cause marine mammals to deflect greatly from their typical
migratory route. Also, even if animals may deflect because of the
presence of the drill rig, the Chukchi Sea is much larger in size than
the length of the drill rig (many dozens to hundreds of miles vs. less
than one football field), and animals would have other means of passage
around the drill rig. While there are other vessels that will be on
location to support the drill rig, most of those vessels will remain
within a 5.5 mi (9 km) of the drill rig (with the exception of the ice
management vessels which will remain approximately 75 mi [121 km] from
the drill rig when conducting ice reconnaissance). In sum, the physical
presence of the drill rig is not likely to cause a significant
deflection to migrating marine mammals.
Potential Impacts From an Oil Spill
Lower trophic organisms and fish species are primary food sources
for Arctic marine mammals. However, as noted earlier in this document,
the offshore areas of the Chukchi Sea are not primary feeding grounds
for many of the marine mammals that may pass through the area.
Therefore, impacts to lower trophic organisms (such as zooplankton) and
marine fishes from an oil spill in the proposed drilling area would not
be likely to have long-term or significant consequences to marine
mammal prey. Impacts would be greater if the oil moves closer to shore,
as many of the marine mammals in the area have been seen feeding at
nearshore sites (such as bowhead and gray whales).
Due to their wide distribution, large numbers, and rapid rate of
regeneration, the recovery of marine invertebrate populations is
expected to occur soon after the surface oil passes. Spill response
activities are not likely to disturb the prey items of whales or seals
sufficiently to cause more than minor effects. Spill response
activities could cause marine mammals to avoid the disturbed habitat
that is being cleaned. However, by causing avoidance, animals would
avoid impacts from the oil itself. Additionally, the likelihood of an
oil spill is expected to be very low, as discussed earlier in this
document.
Potential Impacts From Ice Management Activities
Ice management activities include the physical pushing or moving of
ice to create more open-water in the proposed drilling area and to
prevent ice floes from striking the drill rig. Based on extensive
satellite data analyses of historic and present ice conditions in the
northeastern Chukchi Sea, it is unlikely that hazardous ice will be
present in the vicinity of the jack-up rig. COP therefore expects that
physical management of ice will not be required. However, to ensure
safe drilling operations, COP has developed an Ice Alerts Plan designed
to form an integral part of the drilling operations. The Ice Alerts
Plan contains procedures that will allow early predictions in advance
of potential hazardous ice that could cause damage if it were to come
into contact with the jack-up rig.
The first method of prevention is to identify the presence of
hazardous ice at a large distance from the rig (tens of miles). The ice
edge position will be tracked in near real time using observations from
satellite images and from vessels. Generally, the ice management vessel
will remain within 5.5 mi (9 km) of the drill rig, unless deployed to
investigate migrating ice floes. When investigating ice, vessels will
likely not travel farther than 75 mi (121 km) from the rig. The Ice
Alerts Plan contains procedures for determining how close hazardous ice
can approach before the well needs to be secured and the jack-up moved.
This critical distance is a function of rig operations at that time,
the speed and direction of the ice, the weather forecast, and the
method of ice management.
Based on available historical and more recent ice data, there is
low probability of ice entering the drilling area during the open-water
season. However, if hazardous ice is on a trajectory to approach the
rig, the ice management vessel will be available to respond. One option
for responding is to use the vessel's fire monitor (water cannon) to
modify the trajectory of the floe. Another option is to redirect the
ice by applying pressure with the bow of the ice management vessel,
slowly pushing the ice away from the direction of the drill rig. At
these slow speeds, the vessel uses low power and slow propeller
rotation speed, thereby reducing noise generation from propeller
rotation effects in the water. In case the jack-up rig needs to be
moved due to approaching ice, the support vessels will tow the rig to a
secure location.
Ringed, bearded, spotted, and ribbon seals (along with the walrus)
are dependent on sea ice for at least part of their life history. Sea
ice is important for life functions such as resting, breeding, and
molting. These species are dependent on two different types of ice:
Pack ice and landfast ice. Should ice management activities be
necessary during the proposed drilling program, COP would only manage
pack ice. Landfast ice would not be present during COP's proposed
operations.
The ringed seal is the most common pinniped species in the proposed
project area. While ringed seals use ice year-round, they do not
construct lairs for pupping until late winter/early spring on the
landfast ice. Therefore, since COP plans to conclude drilling by
October 31, COP's activities would not impact ringed seal lairs or
habitat needed for breeding and pupping in the Chukchi Sea. Aerial
surveys in the eastern Chukchi Sea conducted in late May-early June
1999-2000 found that ringed seals were four to ten times more abundant
in nearshore fast and pack ice environments than in offshore pack ice
(Bengtson et al., 2005). Ringed seals can be found on the pack ice
surface in the late spring and early summer in the northern Chukchi
Sea, the latter part of which may overlap with the start of COP's
proposed drilling activities. If an ice floe is pushed into one that
contains hauled out seals, the animals may become startled and enter
the water when the two ice floes collide.
Bearded seals breed in the Bering and Chukchi Seas from mid-March
through early May (several months prior to the start of COP's
operations). Bearded seals require sea ice for molting during the late
spring and summer period. Because this species feeds on benthic prey,
bearded seals occur over the pack ice front over the Chukchi Sea shelf
in summer (Burns and Frost, 1979) but were not associated with the ice
front when it receded over deep water (Kingsley et al., 1985).
The spotted seal does not breed in the Chukchi Sea. Spotted seals
molt most intensely during May and June and then move to the coast
after the sea ice has melted. Ribbon seals are not known to breed in
the Chukchi Sea. From July-October, when sea ice is absent, the ribbon
seal is entirely pelagic, and its distribution is not well known
(Burns, 1981; Popov, 1982). Therefore, ice used by bearded, spotted,
and ribbon seals needed for life functions such as breeding and molting
would not be impacted as a result of COP's drilling program since these
life functions do not occur in the proposed project area or at the same
time as COP's operations. For ringed seals, ice management activities
would occur during a time when life functions such as breeding,
pupping, and molting do not occur in the proposed activity area.
Additionally, these life functions normally occur on
[[Page 12569]]
landfast ice, which will not be impacted by COP's activity.
Based on the preceding discussion of potential types of impacts to
marine mammal habitat, overall, the proposed specified activity is not
expected to cause significant impacts on habitats used by the marine
mammal species in the proposed project area or on the food sources that
they utilize.
Proposed Mitigation
In order to issue an incidental take authorization (ITA) under
Sections 101(a)(5)(A) and (D) of the MMPA, NMFS must, where applicable,
set forth the permissible methods of taking pursuant to such activity,
and other means of effecting the least practicable impact on such
species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of such species or stock for taking for certain
subsistence uses (where relevant). This section summarizes the
mitigation measures proposed for implementation by COP. Later in this
document in the ``Proposed Incidental Harassment Authorization''
section, NMFS lays out the proposed conditions for review, as they
would appear in the final IHA (if issued).
Exclusion radii for marine mammals around sound sources are
customarily defined as the distances within which received sound levels
are greater than or equal to 180 dB re 1 [mu]Pa (rms) for cetaceans and
greater than or equal to 190 dB re 1 [mu]Pa (rms) for pinnipeds. These
exclusion criteria are based on an assumption that sounds at lower
received levels will not injure these animals or impair their hearing
abilities, but that higher received levels might have such effects. It
should be understood that marine mammals inside these exclusion zones
will not necessarily be injured, as the received sound thresholds which
determine these zones were established prior to the current
understanding that significantly higher levels of sound would be
required before injury would likely occur (see Southall et al., 2007).
With respect to Level B harassment, NMFS' practice has been to apply
the 120 dB re 1 [mu]Pa (rms) received level threshold for underwater
continuous sound levels and the 160 dB re 1 [mu]Pa (rms) received level
threshold for underwater impulsive sound levels. As noted earlier in
this document and in O'Neill et al. (2012), the source level of the
drill rig does not meet the criteria requiring exclusion zones.
Therefore, mitigation measures similar to those required for seismic
surveys are not proposed for the drilling only portion of the program.
General Mitigation Measures
COP proposes to implement several mitigation measures regarding
operation of vessels and aircraft. These measures would limit speed and
vessel movements in the presence of marine mammals and restrict flight
altitudes except during takeoff, landing, and in emergency situations.
The exact measures (as proposed) can be found later in this document in
the ``Proposed Incidental Harassment Authorization'' section.
VSP Airgun Mitigation Measures
COP proposes to implement standard mitigation measures used in
previous seismic surveys, including ramp-ups, power downs, and
shutdowns. The received sound levels have been estimated using an
acoustic model (see Attachment A of COP's IHA application). These
modeled distances will be used to establish exclusion zones for the
implementation of the mitigation measures during the first VSP data
acquisition run. The exclusion zones (i.e., 180 dB rms for cetaceans
and 190 dB rms for pinnipeds) might change for subsequent VSP data
acquisition runs after the distances have been verified based on
acoustic field measures (more details are provided in the ``Proposed
Monitoring and Reporting'' section later in this document). The VSP
data acquisition runs will start during daylight hours.
A ramp up of an airgun array provides a gradual increase in sound
levels and involves a step-wise increase in the number and total volume
of airguns firing until the full volume is achieved. The purpose of a
ramp up (or ``soft start'') is to ``warn'' cetaceans and pinnipeds in
the vicinity of the airguns and to provide the time for them to leave
the area and thus avoid any potential injury or impairment of their
hearing abilities.
Ramp-up will begin with the smallest airgun in the array. COP
intends to double the number of operating airguns at 1-min intervals.
Since the airgun operation at each geophone station only lasts about 1
min, this interval should be adequate and also reduces the total
emission of airgun sounds. During the ramp-up, observers will scan the
exclusion zone for the full airgun array for presence of marine
mammals.
The entire exclusion zone must be visible during the 30-minute
lead-in to a full ramp up. If the entire exclusion zone is not visible,
then ramp up from a cold start cannot begin. If a marine mammal(s) is
sighted within the exclusion zone during the 30-minute watch prior to
ramp up, ramp up will be delayed until the marine mammal(s) is sighted
outside of the applicable exclusion zone or the animal(s) is not
sighted for at least 15 minutes for small odontocetes and pinnipeds or
30 minutes for baleen whales. No ramp-up of airguns will be conducted
between 1-min airgun operations at subsequent geophone stations (i.e.,
following the relocation of the geophone within the wellbore) if the
duration of the relocation is 30 min or less, if the exclusion zone of
the full array has been visible, and no marine mammals have been
sighted within the applicable exclusion zones or during poor visibility
or darkness if one airgun has been operating continuously during the
geophone relocation period.
A power down is the immediate reduction in the number of operating
energy sources from all firing to some smaller number. A shutdown is
the immediate cessation of firing of all energy sources. The arrays
will be immediately powered down whenever a marine mammal is sighted
approaching close to or within the applicable exclusion zone of the
full arrays but is outside the applicable exclusion zone of the single
source. If a marine mammal is sighted within the applicable exclusion
zone of the single energy source, the entire array will be shutdown
(i.e., no sources firing). The same 15 and 30 minute sighting times
described for ramp up also apply to starting the airguns again after
either a power down or shutdown.
Oil Spill Response Plan
In accordance with BSEE regulations, COP has developed an Oil Spill
Response Plan (OSRP) for its Chukchi Sea exploration drilling program.
The OSRP is currently under review by DOI and will be shared with other
agencies, including NOAA, for their review as well. A final
determination on the adequacy of the COP's OSRP is expected prior to
the start of drilling operations. In the unlikely event of a large or
very large oil spill, COP would work with the Unified Command,
including representatives of the local communities, to use methods that
would mitigate impacts of a response on subsistence activities.
Proposed Mitigation Measure Conclusion
NMFS has carefully evaluated COP's proposed mitigation measures and
considered a range of other measures in the context of ensuring that
NMFS prescribes the means of effecting the least practicable impact on
the affected marine mammal species and stocks and their habitat. Our
evaluation of potential
[[Page 12570]]
measures included consideration of the following factors in relation to
one another:
The manner in which, and the degree to which, the
successful implementation of the measure is expected to minimize
adverse impacts to marine mammals;
The proven or likely efficacy of the specific measure to
minimize adverse impacts as planned; and
The practicability of the measure for applicant
implementation.
Proposed measures to ensure availability of such species or stock
for taking for certain subsistence uses is discussed later in this
document (see ``Impact on Availability of Affected Species or Stock for
Taking for Subsistence Uses'' section).
Proposed Monitoring and Reporting
In order to issue an ITA for an activity, Section 101(a)(5)(D) of
the MMPA states that NMFS must, where applicable, set forth
``requirements pertaining to the monitoring and reporting of such
taking''. The MMPA implementing regulations at 50 CFR 216.104 (a)(13)
indicate that requests for ITAs must include the suggested means of
accomplishing the necessary monitoring and reporting that will result
in increased knowledge of the species and of the level of taking or
impacts on populations of marine mammals that are expected to be
present in the proposed action area.
Monitoring Measures Proposed by COP
The monitoring plan proposed by COP can be found in the Marine
Mammal Monitoring and Mitigation Plan (4MP; Attachment B of COP's
application; see ADDRESSES). The plan may be modified or supplemented
based on comments or new information received from the public during
the public comment period or from the peer review panel (see the
``Monitoring Plan Peer Review'' section later in this document). A
summary of the primary components of the plan follows. Later in this
document in the ``Proposed Incidental Harassment Authorization''
section, NMFS lays out the proposed monitoring and reporting
conditions, as well as the mitigation conditions, for review, as they
would appear in the final IHA (if issued).
(1) Visual Observers
The distances at which received sound levels occur that have the
potential to cause Level B behavioral harassment (120 dB rms for
continuous sounds) are 689 ft (210 m) for drilling only and about 5 mi
(8 km) for drilling and support vessel activity (O'Neill et al., 2011).
Protected Species Observers (PSOs) at the drill rig will monitor this
zone, using big eye binoculars, documenting presence and behavior of
marine mammals during these activities. At least four PSOs will be
located on the drill rig to collect marine mammal data during drilling
and resupply operations. The PSOs will also collect data and implement
mitigation measures during the VSP data acquisition runs. Two PSOs will
be present on the ice management vessel, which will be on standby
within 5.5 mi (9 km) of the drill rig, except when conducting ice
reconnaissance.
Biologist-observers will have previous marine mammal observation
experience, and field crew leaders will be highly experienced with
previous vessel-based marine mammal monitoring projects. Resumes for
those individuals will be provided to NMFS so that NMFS can review and
accept their qualifications. Inupiat observers will be experienced in
the region, familiar with the marine mammals of the area, and complete
a NMFS approved observer training course designed to familiarize
individuals with monitoring and data collection procedures. A handbook,
adapted for the specifics of the planned COP drilling program, will be
prepared and distributed beforehand to all PSOs.
PSOs will watch for marine mammals from the best available vantage
point on the drillship and support vessels. PSOs will scan
systematically with the unaided eye and 7 x 50 reticle binoculars,
supplemented with ``Big-eye'' binoculars. Personnel on the bridge will
assist the PSOs in watching for marine mammals.
When a marine mammal sighting is made, the following information
will be recorded:
Species, group size, number of juveniles (where possible),
behavior when first sighted and after initial sighting, heading (if
consistent), bearing and distance from PSO, apparent reaction to
activities, and pace;
Time, location, vessel speed and activity (where
applicable), sea state, ice cover, visibility, and sun glare;
Positions of other vessels in the vicinity of the PSO
location or the position and distance of the jack-up rig from the
vessel, where applicable; and
Ship's position and speed (for PSO on vessels) or the
drill rig activity (i.e. drilling or not, for PSOs on the drill rig),
water depth, sea state, ice cover, visibility, and sun glare during the
watch.
During helicopter transfers to and from the drill rig, PSOs will
observe and record marine mammal sightings according to a standardized
protocol.
PSOs may use a laser rangefinder to test and improve their
abilities for visually estimating distances to objects in the water.
However, previous experience showed that a Class 1 eye-safe device was
not able to measure distances to seals more than about 230 ft (70 m)
away. The device was very useful in improving the distance estimation
abilities of the observers at distances up to about 1968 ft (600 m)--
the maximum range at which the device could measure distances to highly
reflective objects such as other vessels. Humans observing objects of
more-or-less known size via a standard observation protocol, in this
case from a standard height above water, quickly become able to
estimate distances within about 20% when given immediate
feedback about actual distances during training.
(2) Acoustic Monitoring
Sound levels from drilling activities and vessels are expected to
vary significantly with time due to variations in the operations and
the different types of equipment used at different times onboard the
drill rig. The goals of the project-specific acoustic monitoring
program are to (1) Quantify the absolute sound levels produced by
drilling and to monitor their variations with time, distance and
direction from the drill rig; (2) measure the sound levels produced by
vessels operating in support of drilling operations; (3) measure sounds
from VSP data acquisition runs; and (4) detect vocalization of marine
mammals. To accomplish these goals, implementation of autonomous
monitoring using bottom-founded acoustic recorders is proposed during
exploration drilling.
COP proposes that monitoring of sound levels from drilling and
vessel activities, as well as from the VSP airguns, will occur on a
continuous basis throughout the entire drilling season with a set of
bottom-founded acoustic recorders. At least four recorders will be
deployed on the seafloor at distances of approximately 0.31 mi (0.5
km), 0.62 mi (1 km), 2.5 mi (4 km), and 6.2 mi (10 km) from the drill
rig. The bottom-founded recorders will be set to record at a sample
rate of 16 or 32 kilohertz (kHz), providing useful acoustic bandwidth
to 8 or 16 kHz. Calibrated reference hydrophones will be used for the
measurements, capable of measuring absolute broadband sound levels
between 90 and 200 dB re [mu]Pa rms. The deployment of the bottom-
founded acoustic monitoring equipment will occur just prior to
placement of the drill rig at the location(s) where COP intends to
drill an exploration well.
[[Page 12571]]
After the first VSP data acquisition run, the recorders will be
retrieved and the data downloaded. Recorders will then be deployed
again and will remain in place until completion of all drilling
activities. The three main objectives of the bottom-founded autonomous
hydrophones are: (1) Provide long duration recordings capturing sound
levels of all operations performed at the drill rig and of all vessel
movements in the vicinity through post-season analyses; (2) calculate
source levels, and distances to sound levels of 160 dB and 120 dB re
1[mu]Pa rms from drilling activities and vessels supporting the drill
rig and distances to 160 dB from VSP airgun sounds; and (3) record
marine mammal vocalizations during the drilling season to be compared
with visual observations during post-season analyses.
Additional details on data analysis for the types of monitoring
described here (i.e., visual PSO and acoustic) can be found in the 4MP
in COP's application (see ADDRESSES).
Monitoring Plan Peer Review
The MMPA requires that monitoring plans be independently peer
reviewed ``where the proposed activity may affect the availability of a
species or stock for taking for subsistence uses'' (16 U.S.C.
1371(a)(5)(D)(ii)(III)). Regarding this requirement, NMFS' implementing
regulations state, ``Upon receipt of a complete monitoring plan, and at
its discretion, [NMFS] will either submit the plan to members of a peer
review panel for review or within 60 days of receipt of the proposed
monitoring plan, schedule a workshop to review the plan'' (50 CFR
216.108(d)).
NMFS convened an independent peer review panel, comprised of
experts in the fields of marine mammal ecology and underwater
acoustics, to review COP's 4MP for Offshore Exploration Drilling in the
Devils Paw Prospect, Chukchi Sea, Alaska. The panel met on January 8-9,
2013. NMFS anticipates receipt of the panel's report containing their
recommendations on the 4MP shortly. NMFS will consider all
recommendations made by the panel, incorporate appropriate changes into
the monitoring requirements of the IHA (if issued), and publish the
panel's findings and recommendations in the final IHA notice of
issuance or denial document.
Reporting Measures
(1) Sound Source Verification and Characterization Report
COP will be required to submit a report of the acoustic monitoring
results noting the source levels and received levels (in 10 dB
increments down to 120 dB) from the jack-up rig, support vessels (also
while in DP mode), and of the VSP airgun array. Additional information
to be reported is contained in COP's 4MP. Initial measurements must be
provided to NMFS within 120 hr of collection and analysis of those
data. This report will specify the distances of the exclusion zones
that were adopted for the VSP data acquisition runs. Prior to
completion of these measurements, COP will use the radii outlined in
their application and elsewhere in this document.
(2) Technical Reports
The results of COP's 2014 Chukchi Sea exploratory drilling
monitoring program (i.e., vessel-based, aerial, and acoustic) will be
presented in the ``90-day'' and Final Technical reports, as required by
NMFS under the proposed IHA. COP proposes that the Technical Reports
will include: (1) Summaries of monitoring effort (e.g., total hours of
effort for rig-based observations or observations from the ice
management vessel when stationary and total kilometer of effort for
non-stationary vessel-based observations); (2) effective area of
observation and marine mammal distribution through study period
(accounting for sea state and other factors affecting visibility and
detectability of marine mammals); (3) analyses of the effects of
various factors influencing detectability of marine mammals (e.g., sea
state, number of observers, and fog/glare); (4) species composition,
occurrence, and distribution of marine mammal sightings, including
date, numbers, age/size/gender categories (if determinable), group
sizes, and ice cover; (5) sighting rates of marine mammals during
periods with and without drilling activities (and other variables that
could affect detectability); (6) initial sighting distances and closest
point of approach versus drilling state; (7) observed behaviors and
types of movements versus drilling state; (8) numbers of sightings/
individuals seen versus drilling state; (9) distribution around the
drill rig and support vessels versus drilling state; and (10) estimates
of take by harassment.
The initial technical report is due to NMFS within 90 days of the
completion of COP's Chukchi Sea exploratory drilling program. The ``90-
day'' report will be subject to review and comment by NMFS. Any
recommendations made by NMFS must be addressed in the final report
prior to acceptance by NMFS.
(3) Notification of Injured or Dead Marine Mammals
COP will be required to notify NMFS' Office of Protected Resources
and NMFS' Stranding Network of any sighting of an injured or dead
marine mammal. Based on different circumstances, COP may or may not be
required to stop operations upon such a sighting. COP will provide NMFS
with the species or description of the animal(s), the condition of the
animal(s) (including carcass condition if the animal is dead),
location, time of first discovery, observed behaviors (if alive), and
photo or video (if available). The specific language describing what
COP must do upon sighting a dead or injured marine mammal can be found
in the ``Proposed Incidental Harassment Authorization'' section of this
document.
Estimated Take by Incidental Harassment
Except with respect to certain activities not pertinent here, the
MMPA defines ``harassment'' as: any act of pursuit, torment, or
annoyance which (i) has the potential to injure a marine mammal or
marine mammal stock in the wild [Level A harassment]; or (ii) has the
potential to disturb a marine mammal or marine mammal stock in the wild
by causing disruption of behavioral patterns, including, but not
limited to, migration, breathing, nursing, breeding, feeding, or
sheltering [Level B harassment]. Only take by Level B behavioral
harassment is anticipated as a result of the proposed drilling program.
Noise propagation from the drill rig, associated support vessels in DP
mode, and the airgun array are expected to harass, through behavioral
disturbance, affected marine mammal species or stocks. Additional
disturbance to marine mammals may result from aircraft overflights and
visual disturbance of the drill rig or support vessels. However, based
on the flight paths and altitude, impacts from aircraft operations are
anticipated to be localized and minimal in nature.
The full suite of potential impacts to marine mammals from various
industrial activities was described in detail in the ``Potential
Effects of the Specified Activity on Marine Mammals'' section found
earlier in this document. The potential effects of sound from the
proposed exploratory drilling program might include one or more of the
following: tolerance; masking of natural sounds; behavioral
disturbance; non-auditory physical effects; and, at least in theory,
temporary or permanent hearing impairment (Richardson et al., 1995b).
[[Page 12572]]
As discussed earlier in this document, NMFS estimates that COP's
activities will most likely result in behavioral disturbance, including
avoidance of the ensonified area or changes in speed, direction, and/or
diving profile of one or more marine mammals. For reasons discussed
previously in this document, hearing impairment (TTS and PTS) is highly
unlikely to occur based on the fact that most of the equipment to be
used during COP's proposed drilling program does not have source levels
high enough to elicit even mild TTS and/or the fact that certain
species are expected to avoid the ensonified areas close to the
operations. Additionally, non-auditory physiological effects are
anticipated to be minor, if any would occur at all. Finally, based on
the proposed mitigation and monitoring measures described earlier in
this document and the fact that the source level for the drill rig is
estimated to be below 170 dB re 1 [mu]Pa (rms), no injury or mortality
of marine mammals is anticipated as a result of COP's proposed
exploratory drilling program.
For continuous sounds, such as those produced by drilling
operations and during DP, NMFS uses a received level of 120-dB (rms) to
indicate the onset of Level B harassment. For impulsive sounds, such as
those produced by the airgun array during the VSP surveys, NMFS uses a
received level of 160-dB (rms) to indicate the onset of Level B
harassment. COP provided calculations for the 120-dB isopleths produced
by the jack-up rig and the support vessels in DP and then used those
isopleths to estimate takes by harassment. Additionally, COP provided
calculations for the 160-dB isopleth produced by the airgun array and
then used that isopleth to estimate takes by harassment. COP provides a
full description of the methodology used to estimate takes by
harassment in its IHA application (see ADDRESSES), which is also
provided in the following sections.
COP has requested authorization to take bowhead, gray, fin,
humpback, minke, killer, and beluga whales, harbor porpoise, and
ringed, spotted, bearded, and ribbon seals incidental to exploration
drilling, support vessels operating in DP mode, ice management, and VSP
activities.
COP's density estimates are based on the best available peer
reviewed scientific data, when available. In cases where the best
available data were collected in regions, habitats, or seasons that
differ from the proposed survey activities, adjustments to reported
population or density estimates were made to account for these
differences insofar as possible. In cases where the best available peer
reviewed data were based on data from more than a decade old, more
recent information was used. Species abundance information in the
northeastern Chukchi Sea from the 2008-2010 COMIDA (now referred to as
ASAMM) marine mammal aerial surveys (Clarke and Ferguson, 2010; Clarke
et al., 2011) and the 2008-2010 vessel-based Chukchi Sea Environmental
Studies Program (CSESP; Aerts et al., 2011) contain current knowledge
of some whale and seal species. The data from the COMIDA aerial survey
have undergone several reviews, so although not officially peer
reviewed, these recent abundance and distribution data were determined
to be more representative than older peer reviewed publications for
bowhead and gray whales. The CSESP data are as of yet preliminary so
are presently only used as a comparison to available peer reviewed
data, unless no other information was available. In those cases the
CSESP data were used to estimate densities. After reviewing the density
estimates, NMFS determined that the data used are appropriate.
Because most cetacean species show a distinct seasonal
distribution, density estimates for the northeastern Chukchi Sea have
been derived for two time periods: the summer period (covering July and
August) and the fall period (covering September and October). Animal
densities encountered in the Chukchi Sea during both of these time
periods will further depend on the presence of ice. However, if ice is
present close to the project area, drilling operations will not start
or will be halted, so cetacean densities related to ice conditions are
not included in COP's IHA application. Pinniped species in the Chukchi
Sea do not show a distinct seasonal distribution during the period
July-October (Aerts et al., 2011) and as such density estimates derived
for seal species are used for both the summer and fall periods.
Some sources from which densities were used include correction
factors to account for perception and availability bias in the reported
densities. Perception bias is associated with diminishing probability
of sighting with increasing lateral distance from the trackline, where
an animal is present at the surface but could be missed. Availability
bias refers to the fact that the animal might be present but is not
available at the surface. In cases where correction factors were not
included in the reported densities, the best available correction
factors were applied.
To account for variability in marine mammal presence, COP derived
maximum density estimates were in addition to average density
estimates. Except where specifically noted, the maximum estimates have
been calculated as double the average estimates. COP determined that
this factor was large enough to allow for chance encounters with
unexpected large groups of animals or for overall higher densities than
expected. Table 8 in COP's IHA application indicates that the ``average
estimate'' for humpback, fin, minke, and killer whales is either zero
or one. Additionally, Table 8 in the application indicates that the
``average estimate'' for harbor porpoise and beluga whales is low.
Therefore, to account for the fact that these species listed as being
potentially taken by harassment in this document may occur in COP's
proposed drilling sites during active operations, NMFS either used the
``maximum estimates'' or made an estimate based on typical group size
for a particular species.
Estimated densities of marine mammals in the Chukchi Sea project
area during the summer (July-August) and fall (September-October)
periods are presented in Table 4 in COP's application and Table 1 here.
Descriptions of the individual density estimates shown in the tables
are presented next.
Cetacean Densities
Eight cetacean species are known to occur in the northeastern
Chukchi Sea. Of these, bowhead, beluga, gray, and killer whales and
harbor porpoise are likely to be encountered in the proposed project
area. Fin, humpback, and minke whales may occur but likely in lower
numbers than the other cetacean species.
(1) Beluga Whales
Summer densities of belugas in offshore waters of the Chukchi Sea
are expected to be low, with higher densities at the ice-margin and in
nearshore areas. Aerial surveys have recorded few belugas in the
offshore Chukchi Sea during the summer months (Moore et al., 2000b).
COMIDA aerial surveys flown in 2008, 2009, and 2010 reported a total of
733 beluga sightings during >32,202 mi (51,824 km) of on-transect
effort, resulting in 0.0141 beluga whales per km (Clarke et al., 2011).
Belugas were seen every month except September, with most sightings in
July.
There was one sighting of nearly 300 belugas nearshore between
Wainwright and Icy Cape in 2009, and several hundred belugas were
sighted in Elson Lagoon, east of Pt. Barrow in 2010. Group size ranged
from 1 to 480 individuals. Highest sighting rate per
[[Page 12573]]
depth zone was in shallow water (<= 115 ft [35 m] depth), which was
likely due to the large groups described above. No beluga whales were
sighted during the 2008-2010 vessel-based marine mammal CSESP surveys
that covered the Devils Paw prospect and two other lease areas in the
northeastern Chukchi Sea (Brueggeman et al., 2009b, 2010; Aerts et al.,
2011). Some beluga vocalizations were detected in October 2009 around
Barrow and in the Burger lease area by acoustic recorders deployed as
part of the CSESP program, but none in the Devils Paw prospect (Delarue
et al., 2011). Also, no beluga sightings were reported during >11,185
mi (18,000 km) of vessel-based effort in good visibility conditions
during 2006-2008 industry operations in the northeastern Chukchi Sea
(Haley et al., 2010).
The COMIDA aerial survey summer and fall data (Clarke et al., 2011)
were used to calculate expected average densities in the Devils Paw
prospect. Because the reported densities (Whales Per Unit Effort) are
not corrected for perception or availability bias, a f(0) value of
2.841 and g(0) value of 0.58 from Harwood et al. (1996) were applied to
arrive at estimated corrected densities, using the equation from
Buckland et al. (2001). In the months July and August, two on-transect
beluga sightings of five animals were observed in water depths of 118-
164 ft (36-50 m) along 7,447 mi (11,985 km) line transect. After
applying the correction factors mentioned above, this resulted in a
density of 0.0010 whales/km\2\ (Table 4 in COP's application and Table
1 here). The three on-transect beluga sightings of six animals recorded
in the period September-October along 6,236 mi (10,036 km) effort
resulted in a corrected density of 0.0015 whales/km\2\.
The absence of any beluga sightings during the 2008-2010 CSESP
marine mammal research (Brueggeman et al., 2009b, 2010; Aerts et al.,
2011), the 2006-2008 industry programs (Haley et al., 2010), and the
low number of acoustic detections in the vicinity of the project area
(Delarue et al., 2011), are consistent with the relative low summer and
fall densities in water depths of 118-164 ft (36-50 m) as calculated
with the COMIDA aerial survey data.
(2) Bowhead Whales
Most bowhead whales that will be observed in the northeastern
Chukchi Sea are either migrating north to feeding grounds in the
eastern Beaufort Sea during spring (prior to the start of COP's
proposed activities), or migrating south to their wintering grounds in
the Bering Sea during the fall. By July, most bowhead whales have
passed Point Barrow, although some have been visually and acoustically
detected during the entire summer in low numbers in the northeastern
Chukchi Sea (Moore et al., 2010; Thomas et al., 2010; Quakenbush et
al., 2010; Clarke and Ferguson, in prep.). Bowheads are more widely
scattered in the northeastern Chukchi Sea during the fall migration but
generally keep an offshore route. During aerial surveys in the COMIDA
area from 1982-1991 and 2008-2010, a total of 88 on-effort sightings of
121 bowhead whales were observed. Bowhead whales were seen in all
months from June to October, with the greatest number of sightings
occurring in October (Clarke et al., 2011; Clarke and Ferguson, in
prep.). Similarly, bowhead whales were sighted in July-August during
nearshore aerial surveys conducted in 2006-2008 in the northeastern
Chukchi Sea but with increasing number of sightings in September and
October (Thomas et al., 2010). Vessel-based CSESP marine mammal surveys
conducted in Devils Paw prospect and two other lease areas in the
northeastern Chukchi Sea recorded a total of 40 sightings of 59 animals
during 2008-2010 with all but one sighting in October (Brueggeman et
al., 2009, 2010; Aerts et al., 2011).
The estimate of summer and fall bowhead whale density in the
Chukchi Sea was calculated using the 2008-2010 COMIDA aerial survey
data (Clarke and Ferguson, in prep.). No bowhead whales were sighted
during the 7,447 mi (11,985 km) of survey effort in waters of 118-164
ft (36-50 m) during July-August. However, for density estimates in this
IHA, COP assumed there was one sighting of one bowhead. To improve the
understanding of what factors significantly affect bowhead whale
detections from aerial surveys, a distance detection function was
estimated using 25 years of aerial line transect surveys in the Bering,
Chukchi and Beaufort Seas (Givens et al., 2010). Because the correction
factor from this study is lower than the estimates by Thomas et al.
(2002), COP used the higher values to estimate densities for the
purpose of this IHA. When applying a f(0) value of 2 and a g(0) value
of 0.07 from Thomas et al. (2002), the summer density was estimated to
be 0.0012 whales/km\2\ (Table 4 in COP's application and Table 1 here).
Clarke and Ferguson (in prep.) reported 14 sightings of 15 individuals
during 6,236 mi (10,036 km) of on transect aerial survey effort in
September and October 2008-2010. Applying the same f(0) and g(0) values
as for the summer density estimate, the bowhead density estimate for
the fall is 0.0214 whales/km\2\ (Table 4 in COP's application and Table
1 here). A total of 36 on-transect sightings of 55 bowheads were
observed along 8,169 mi (13,146 km) transect effort during the vessel-
based CSESP marine mammal surveys in September and October. Applying
the same correction factors as above resulted in a corrected bowhead
density of 0.0598 whales/km\2\. This high density coincided with a peak
in whale migration the first week of October, which was also apparent
on the acoustic records (Delarue et al., 2011). Although none of these
sightings were in the Devils Paw prospect, the maximum fall bowhead
density estimate has been calculated as triple the average estimates,
to cover for such migration peaks.
(3) Gray Whales
Gray whale densities are expected to be highest in nearshore areas
during the summer months with decreasing numbers in the fall. Moore et
al. (2000b) reported a scattered distribution of gray whales generally
limited to nearshore areas where most whales were observed in water
less than 115 ft (35 m) deep. Nearshore aerial surveys along the
Chukchi coast also reported substantial declines in the sighting rates
of gray whales in the fall (Thomas et al., 2010). The average open-
water summer and fall densities presented in Table 4 in COP's
application and Table 1 here were calculated from the 2008-2010 COMIDA
aerial survey data (Clarke and Ferguson, in prep.). The summer data for
water depths 118-164 ft (36-50 m) included 54 sightings of 73
individuals during 7,447 mi (11,985 km) of on-transect effort. Applying
the correction factors f(0) = 2.49 and g(0) = 0.95 (Forney and Barlow,
1998 Table 1, based on aerial survey data) resulted in a summer density
of 0.0080 whales/km\2\ (Table 4 in COP's application and Table 1 here).
The number of gray whale sightings in the offshore study areas during
the 2008-2010 CSESP marine mammal survey were limited in July and
August; eight sightings of nine animals along 4,223 mi (6,796 km) on-
transect effort. Most of these animals were observed nearshore of
Wainwright (Brueggeman et al., 2009, 2010; Aerts et al., 2011) and only
two sightings of three animals were recorded in the Devils Paw
Prospect. Densities from vessel based surveys in the Chukchi Sea during
non-seismic periods and locations in July and August of 2006-2008
(Haley et al., 2010) ranged from 0.0021 to 0.0080 whales/km\2\ with a
maximum 95 percent CI of 0.0336.
[[Page 12574]]
In the fall, gray whales may be dispersed more widely through the
northern Chukchi Sea (Moore et al., 2000b; Clarke and Ferguson, in
prep.), but overall densities are likely to be decreasing as the whales
begin migrating south. The average fall density was calculated from 15
sightings of 19 individuals during 6,236 mi (10,036 km) of on-transect
effort in water 118-164 ft (36-50 m) deep during September and October
(Clarke and Ferguson, in prep.). Applying the same f(0) and g(0) values
as for the summer density, resulted in 0.0025 whales/km\2\ (Table 4 in
COP's application and Table 1 here). During the CSESP survey in
September and October, 25 gray whale sightings of 36 individuals were
observed along 8,169 mi (13,146 km) of on-transect effort, resulting in
an uncorrected density of 0.0027 whales/km\2\. Most of these whales
were, however, observed nearshore of Wainwright (within 31 mi [50 km]
from the coast) and none in the Devils Paw Prospect. Densities from
vessel based surveys in the Chukchi Sea during non-seismic periods and
locations in July and August of 2006-2008 (Haley et al., 2010) ranged
from 0.0026 to 0.0042 whales/km\2\ with a maximum 95% CI of 0.0277.
(4) Harbor Porpoise
Distribution and abundance data of harbor porpoise were very
limited prior to 2006, and presence of the harbor porpoise was expected
to be very low in the northeastern Chukchi Sea.
Starting in 2006, several vessel-based marine mammal observer
programs took place in the northeastern Chukchi Sea as part of seismic
and shallow hazard survey monitoring and mitigation plans (Haley et
al., 2010). During these surveys, 37 sightings of 61 harbor porpoises
were reported. Three on-transect sightings of seven harbor porpoises
were observed in the Devils Paw prospect in July and August along 4,223
mi (6,796 km) of on-transect effort during the CSESP marine mammal
surveys. No harbor porpoises were observed in the fall (Brueggeman et
al., 2009, 2010; Aerts et al., 2011). COP used the 2008-2010 CSESP data
to calculate densities for the purpose of this IHA. The uncorrected
average density for the summer based on the three year CSESP data is
0.0010 porpoises/km\2\ (Table 4 in COP's application and Table 1 here).
As a comparison, summer density estimates from 2006-2008 marine mammal
monitoring and mitigation programs during non-seismic periods ranged
from 0.0008 to 0.0015 animals/km\2\ with a maximum 95 percent CI of
0.0079 animals/km\2\ (Haley et al., 2010).
Assuming that one sighting of one animal would have been observed
along 8,169 mi (13,146 km) transect effort during the 2008-2010 CSESP
surveys in the fall, the average uncorrected fall density is 0.0001
porpoises/km\2\ (Table 4 in COP's application and Table 1 here). Harbor
porpoise densities recorded during non-seismic periods in the fall
months of 2006-2008 ranged from 0.0002 to 0.0011 animals/km\2\ with a
maximum 95 percent CI of 0.0093 animals/km\2\. The maximum value of
0.0011 animals/km\2\ from these surveys was used as the maximum fall
density estimate for this IHA (Table 4 in COP's application and Table 1
here).
(5) Other Cetaceans
The remaining cetacean species that could be encountered in the
Chukchi Sea during COP's planned activities include the humpback, fin,
minke, and killer whales. The northeastern Chukchi Sea is at the
northern edge of the known distribution range of most of these animals,
although in recent years several sightings of some of these cetaceans
were recorded in the area. During the 2008-2010 marine mammal aerial
surveys in the COMIDA area, one humpback and one fin whale were
observed, but none were observed in 1982-1991 in the same area (Clarke
et al., 2011). Two sightings of four fin whales were recorded in 2008
in the northeastern Chukchi Sea during 2006-2008 marine mammal
monitoring programs from seismic and shallow hazard survey vessels
(Haley et al., 2010). During the vessel-based 2008-2010 CSESP marine
mammal surveys, two killer whale pods of 9 individuals were observed in
the Devils Paw prospect and also one minke whale (Brueggeman et al.,
2009, 2010; Aerts et al., 2011). Although there is evidence of the
occurrence of these animals in the Chukchi Sea, it is unlikely that
more than a few individuals will be encountered during the proposed
activities. The expected average densities of these species for the
purpose of this IHA are therefore estimated at 0.0001 animal/km\2\. The
maximum density estimates have been calculated as quadruple the average
estimates to account for the increasing trend in number of observations
during recent years (Table 4 in COP's application and Table 1 here).
Pinniped Densities
Four species of pinnipeds under NMFS jurisdiction occur in the
Chukchi Sea during COP's proposed activities of which three are most
likely to be encountered: ringed seal, bearded seal, and spotted seal.
Each of these species is associated with presence of ice and the
nearshore area. For ringed and bearded seals the ice margin is
considered preferred habitat during most seasons (as compared to the
nearshore areas). Spotted seals are considered to be predominantly a
coastal species except in the spring when they may be found in the
southern margin of the retreating sea ice. Satellite tagging studies
have shown that spotted seals sometimes undertake long excursions into
offshore waters during summer (Lowry et al., 1994, 1998). Ribbon seals
were observed during the vessel-based CSESP surveys in 2008, when ice
was present in the area (Brueggeman et al., 2009), and they were also
reported in very small numbers within the northeastern Chukchi Sea by
observers on industry vessels (Haley et al., 2010).
Table 1--Estimated Densities of Cetaceans and Pinnipeds in the Northeastern Chukchi Sea Expected During the
Proposed Drilling Operations in the Devils Paw Prospect During the 2014 Open-Water Season
----------------------------------------------------------------------------------------------------------------
July/August September/October
Density in numbers per square km ---------------------------------------------------
Avg Max Avg Max
----------------------------------------------------------------------------------------------------------------
Beluga whale................................................ 0.0010 0.0020 0.0015 0.0030
Killer whale................................................ 0.0001 0.0004 0.0001 0.0004
Harbor porpoise............................................. 0.0010 0.0020 0.0001 0.0011
Bowhead whale............................................... 0.0012 0.0024 0.0214 0.0641
Gray whale.................................................. 0.0080 0.0160 0.0025 0.0050
Humpback whale.............................................. 0.0001 0.0004 0.0001 0.0004
Fin whale................................................... 0.0001 0.0004 0.0001 0.0004
Minke whale................................................. 0.0001 0.0004 0.0001 0.0004
[[Page 12575]]
Bearded seal................................................ 0.0135 0.0248 0.0135 0.0248
Ringed seal................................................. 0.0516 0.1256 0.0516 0.1256
Spotted seal................................................ 0.0244 0.0355 0.0244 0.0355
Ribbon seal................................................. 0.0020 0.0060 0.0020 0.0060
----------------------------------------------------------------------------------------------------------------
Note: Species listed under the U.S. ESA as Endangered are in italics.
Table 2--Modeled Distances to Received Sound Pressure Level Criteria Used by NMFS for the Relevant Sound Sources
of the Proposed Project and the Areas Used to Estimate the Number of Potential Takes by Harassment
----------------------------------------------------------------------------------------------------------------
Received SPL Modeled Area (km\2\)
Sound source (dB re 1 [mu]Pa) distance (km) used *
----------------------------------------------------------------------------------------------------------------
Continuous sound source
Drilling................................................... 160 db <0.01 .............
120 dB 0.21 .............
Support vessel in dynamic positioning...................... 160 dB 0.71 .............
120 dB 7.90 201
Ice management............................................. 160 dB 0.71 .............
120 dB 7.90 201
Pulsed sound source
VSP airguns................................................ 190 dB 0.16 .............
180 dB 0.92 .............
160 dB 4.90 78.5
120 dB ** 71.0 .............
----------------------------------------------------------------------------------------------------------------
* Areas ensonified with continuous sound levels of 120 dB and pulsed sound levels of 160 dB displayed in this
column were used to estimate the number of marine mammals potentially exposed to these levels (see Section
6.2.1).--means not applicable
** Contours of 120 dB re 1 [mu]Pa for airgun sounds extended beyond the modeling area and as such the distance
shown is based on extrapolation of the data and therefore uncertain.
Aerial survey data from Bengston et al. (2005) were initially used
for bearded and ringed seal densities. However, because these surveys
were conducted in the spring during the seal basking season, the
reported densities might not be applicable for the open-water summer
and fall period. Therefore, the 2008-2010 CSESP vessel-based marine
mammal survey data were used to calculate seal densities. The densities
for spotted and ribbon seals were also based on the 2008-2010 CSESP
marine mammal survey data (Aerts et al., 2011). Perception bias was
accounted for in the CSESP densities, but the number of animals missed
because they were not available for detection was not taken into
account. The assumption was made that all animals available at distance
zero from the observer, this is on the transect line, were detected
[g(0)=1]. The amount of animals missed due to perception bias was
calculated using distance sampling methodology (Buckland et al., 2001;
Buckland et al., 2004). Program Distance 6.1 release 1 (Thomas et al.,
2010) was used to analyze effects of distance and environmental factors
(e.g., sea state, visibility) on the probability of detecting marine
mammal species.
During the CSESP studies, a relatively large percentage of seal
sightings were classified as ringed/spotted seals (meaning it was
either a spotted or a ringed seal) and unidentified seals (meaning it
could be any of the four seal species observed). These sightings had to
be taken into account to avoid an underestimation of densities for each
separate seal species. The ratio of ringed versus spotted seal
densities for each study area and year was used to estimate the
proportional density of each of these two species from the combined
ringed/spotted seal densities. This estimated proportional density was
then added to the observed densities. The same method was used to
proportionally divide the unidentified seal sightings over spotted,
ringed, and bearded seal sightings. Applying the ratio of identified
seal species to the unidentified individuals assumes that the
disability of identification is similar for each species. Considering
the conditions of these occurrences (animals either far away or only at
the surface for a very brief moment), this is likely to be true. The
above described adjustment increased densities for each species but did
not change observed trends in occurrence.
(1) Bearded Seals
Densities from 1999-2000 spring surveys in the offshore pack ice
zone (zone 12P) of the northern Chukchi Sea (Bengtson et al., 2005)
were initially consulted for bearded seal average and maximum summer
densities. A correction factor for bearded seal availability bias,
based on haul out and diving patterns was not available and therefore
not included in the reported densities. Average density of bearded
seals on the offshore pack ice in zone 12P was 0.018 seals/km\2\, with
a maximum density of 0.027 seals/km\2\ (Bengston et al., 2005). During
the 2008-2010 CSESP marine mammal survey, bearded seal density in the
Devils Paw prospect from July-October was 0.025 seals/km\2\ in 2008,
0.004 seals/km\2\ in 2009, and 0.011 seals/km\2\ in 2010 (Aerts et al.,
2011). The average density over these three years was 0.014 seals/
km\2\, and the maximum density was 0.025 seals/km\2\. The average
[[Page 12576]]
density of the CSESP surveys is about 30% lower than reported by
Bengston et al. (2005) and the maximum CSESP densities about 10% lower.
It was decided to use the CSESP average and maximum densities data as
these were gathered in the area of operation during the same season as
the proposed operations (Table 4 in COP's application and Table 1
here).
(2) Ringed Seals
Ringed seal average and maximum summer densities were also
calculated from the 1999-2000 spring aerial survey data in the offshore
pack ice zone (zone 12P) of the northern Chukchi Sea (Bengtson et al.,
2005). Ringed seal availability bias, g(0), based on haul out and
diving patterns was used in the reported densities. Average density of
ringed seals on the offshore pack ice in zone 12P was 0.052 seals/km\2\
and the maximum density 0.81 seals/km\2\ (Bengston et al., 2005).
During the 2008-2010 CSESP marine mammal survey, ringed seal density in
the Devils Paw prospect from July-October was 0.126 seals/km\2\ in
2008, 0.018 seals/km\2\ in 2009, and 0.012 seals/km\2\ in 2010 (Aerts
et al., 2011). The average density over these 3 years was 0.052 seals/
km\2\ and the maximum density 0.126 seals/km\2\. The average density of
the CSESP surveys is very similar to that reported by Bengston et al.
(2005), but the maximum CSESP density was about 6 times lower. As with
the bearded seal density, it was decided to use the CSESP average and
maximum densities data as these were gathered in the area of operation
during the same season as the proposed operations (Table 4 in COP's
application and Table 1 here). The maximum density was obtained in a
year when ice was present in the area.
(3) Spotted Seals
Little information is available on spotted seal densities in
offshore areas of the Chukchi Sea. Spotted seal densities were
calculated based on the data collected during the CSESP marine mammal
survey (Aerts et al., 2011). Spotted seal density in the Devils Paw
prospect from July-October was 0.036 seals/km\2\ in 2008, 0.019 seals/
km\2\ in 2009, and 0.018 seals/km\2\ in 2010 (Aerts et al., 2011). The
average density over these three years was 0.024 seals/km\2\ and the
maximum density 0.036 seals/km\2\ (Table 4 in COP's application and
Table 1 here).
(4) Ribbon Seals
Four ribbon seal sightings of four individuals were recorded in the
Devils Paw prospect during the CSESP survey from July-October 2008
(Brueggeman et al., 2009). No ribbon seals were sighted in 2009 and
2010 (Brueggeman et al., 2010; Aerts et al., 2011). Density calculated
from this limited number of sightings in 2008 was 0.006 seals/km\2\.
The average and maximum densities were 0.002 seals/km\2\ and 0.006
seals/km\2\, respectively. Note that the 2008 density calculated for
this IHA had, as expected, an extremely large coefficient of variation
due to the limited number of sightings.
Estimated Area Exposed to Sounds >120 dB or >160 dB re 1 [mu]Pa rms
An acoustic propagation model (i.e. JASCO's Marine Operations Noise
Model) was used to estimate distances to received rms SPLs of 190, 180,
160, and 120 dB re 1[mu]Pa from the drill rig, support vessel on DP
alongside the drill rig, and from the VSP airguns. The distances to
reach received sound levels of 120 dB re 1 [mu]Pa (for continuous sound
sources, such as drilling activities, support vessels, and ice
management) and 160 dB re 1 [mu]Pa (for pulsed sound sources, such as
the VSP airguns) are used to calculate the potential numbers of marine
mammals potentially harassed by the proposed activities. The distances
to received levels of 180 dB and 190 dB re 1 [mu]Pa (rms) will be used
to establish exclusion zones for mitigation purposes (see the
``Proposed Mitigation'' section earlier in this document). Three
scenarios were considered for modeling:
1. Jack-up rig performing drilling operations (without support
vessels);
2. Jack-up rig performing drilling operations with the support
vessel alongside in DP mode, i.e., maintaining position using
thrusters; and
3. 760 in\3\ ITAGA airgun array operating at the drill site as
representative for VSP data acquisition runs.
The results of these model runs are shown in the report ``Acoustic
Modeling of Underwater Noise from Drilling Operations at the Devils Paw
prospect in the Chukchi Sea'' (Attachment A of COP's application) and
are summarized in Table 5 of COP's application and Table 2 here.
The ice management vessel is part of an ice alerts system and
available to assist operations by conducting ice reconnaissance trips
and protecting the rig from potential ice hazards if necessary. COP
does not expect physical management of ice to be necessary during the
open-water season and does not intend to engage in icebreaking. If ice
floes are determined to require a managed response to protect the drill
rig, the use of fire monitors (water cannons) or the vessel itself to
modify ice floe trajectory is the most likely response. As summarized
earlier in this document, an SPL of about 193 dB re 1[mu]Pa at 1 m was
estimated to be a reasonable peak value for ice management vessels
during different sea ice conditions and modes of propulsion level (Roth
and Schmidt, 2010). Sound levels generated during physical management
of ice are not expected to be as intense as during icebreaking
activities described in most literature. Instead of actually breaking
ice, the vessel will redirect and reposition the ice with slow
movements, pushing it away from the direction of the drill rig at slow
speeds so that the ice floe does not form any hazard to the drilling
operations. At these slow speeds the vessel uses low power, with slow
propeller rotation speed, thereby reducing noise generation from
propeller rotation effects in the water. For the purpose of estimating
the number of marine mammals potentially eliciting behavioral
responses, COP assumed that the distance to received sound pressure
levels of 120 dB re 1[mu]Pa from physical ice management is similar to
that modeled for the support vessel on DP, i.e. 4.9 mi (7.9 km). This
is considered to be an overestimation, since source levels from the
proposed physical management of ice are expected to be much lower than
the 204 dB re 1[mu]Pa used for the support vessel and also lower than
the 193 dB re 1[mu]Pa reported for icebreaking activities.
Potential Number of Takes by Harassment
Although a marine mammal may be exposed to drilling, DP, or ice
management sounds =120 dB (rms) or airgun sounds
=160 dB (rms), not all animals react to sounds at this low
level, and many will not show strong reactions (and in some cases any
reaction) until sounds are much stronger. There are several variables
that determine whether or not an individual animal will exhibit a
response to the sound, such as the age of the animal, previous exposure
to this type of anthropogenic sound, habituation, etc.
The 160 dB criterion is applied to pulsed sounds generated by
airguns during the two or three VSP data acquisition runs that will be
of short duration (with a total of about 2 hrs of airgun activity for
two to three runs per well, not including time required for ramp up).
The 120 dB criterion is applied to sounds from the drill rig for
situations where the support vessel is located alongside the drill rig
in DP mode, i.e., the scenario with highest sound production. This
situation will occur about four times a week for a
[[Page 12577]]
maximum of 6 hrs per occurrence, i.e., about 318 hrs of DP based on 53
trips over the entire drilling season for the ware vessel and 4.5 times
a week, i.e., about 378 hrs for the OSV. The 120 dB criterion is also
applied to any physical management of ice that might occur. For
analytical purposes, physical ice management was conservatively
estimated at up to 72 hrs, only in July and August. The area ensonified
with continuous sound levels of 120 dB re1 [mu]Pa (rms) during drilling
activity only is so small (<0.2 km\2\) that it does not appreciably add
to the total estimated number of marine mammal exposures and is
therefore not included in the calculations.
The area around the drill rig ensonified with pulsed sound levels
>=160 dB re1 [mu]Pa (rms) during VSP runs is estimated at 30 mi\2\
(78.5 km\2\; radius of 3.1 mi or 5 km), and 78 mi\2\ (201 km\2\; radius
of 5 mi or 8 km) for continuous sound levels of >=120 dB re1 [mu]Pa
(rms) during times when the support vessel is attending the rig and
during physical management of ice (Table 5 in COP's application and
Table 2 here).
The potential number of each species that might be exposed to
received continuous SPLs of >=120 dB re 1 [mu]Pa (rms) and pulsed SPLs
of >=160 dB re 1 [mu]Pa (rms) was calculated by multiplying:
The expected (seasonal) species density as provided in
Table 4 of COP's application and Table 1 here;
the anticipated area to be ensonified by the 120 dB re 1
[mu]Pa (rms) SPL (support vessel in DP mode and ice management
activity) and 160 dB re 1 [mu]Pa (rms) SPL (VSP airgun operations); and
the estimated total duration of each of the three
activities within each season expressed in days (24 hrs).
To derive at an estimated total duration for each of the three
activities for each season (summer and fall) the following assumptions
were made:
The total duration during which the support vessel will be
in DP mode is 318 + 378 = 696 hrs. This is the equivalent of 29 days
over the entire season, with 14.5 days in July/August and 14.5 days in
September/October.
Physical management of ice was assumed to take place only
in the early season, and, for analytical purpose, estimated at a total
of 72 hrs. No physical management of ice is assumed in September or
October. If sea ice becomes an issue in October, drilling activities
will likely be halted and the drill rig prepared for demobilization.
The ensonified area of 120 dB re 1[mu]Pa for continuous
sounds of the support vessel in DP mode and active ice management are
assumed to be similar. To be conservative, COP assumed that the
ensonified areas of these two activities will not overlap. The duration
of both of these activities combined, used to calculate marine mammal
exposures to 120 dB re 1 [mu]Pa (rms), is therefore17.5 days (=14.5 +
3) for July/August and 14.5 days for September/October.
The total duration of the two or three VSP data
acquisition runs per well is estimated to be 24 hrs, during which the
airguns will be operating a total of about 2 hrs. Assuming COP will do
additional VSP data acquisition runs for a second well, the total time
of operating airgun activity is estimated about 4 hrs. To be
conservative, COP included airgun time for ramp ups. Therefore, COP
used 12 hrs (0.5 day) in July/August and 12 hrs (0.5 day) in September/
October for the calculations of potential exposures.
Table 6 in COP's application summarizes the number of marine
mammals potentially exposed to continuous SPLs of 120 dB re 1 [mu]Pa
from support vessels on DP and physical ice management. Table 7 in
COP's application summarizes the estimated number of marine mammals
potentially exposed to pulsed SPLs of 160 dB re 1 [mu]Pa during the VSP
runs. The total number of potential marine mammal exposures from all
three activities combined is provided in Table 8 of COP's application.
Additional information is contained in Section 6 of COP's IHA
application.
NMFS is proposing to authorize the maximum take estimates provided
in Table 8 of COP's application, except for the species noted earlier
in this section to account for typical group size of those species.
Table 3 in this document outlines the abundance, proposed take, and
percentage of each stock or population for the 12 species that may be
exposed to sounds =120 dB from the drill rig with support
vessels in DP mode and ice management activities and to sounds
=160 dB from VSP activities in COP's proposed Chukchi Sea
drilling area. Less than 1.3% of each species or stock would
potentially be exposed to sounds above the Level B harassment
thresholds. The take estimates presented here do not take any of the
mitigation measures presented earlier in this document into
consideration. These take numbers also do not consider how many of the
exposed animals may actually respond or react to the proposed
exploration drilling program. Instead, the take estimates are based on
the presence of animals, regardless of whether or not they react or
respond to the activities.
Table 3--Population Abundance Estimates, Total Proposed Level B Take Estimates (When Combining Takes From Drill
Rig Operations, Ice Management, DP, and VSP Surveys), and Percentage of Stock or Population That may be Taken
for the Potentially Affected Species That may Occur in COP's Proposed Chukchi Sea Drilling Area
----------------------------------------------------------------------------------------------------------------
Percentage of
Species Abundance \1\ Total proposed stock or
take population
----------------------------------------------------------------------------------------------------------------
Beluga Whale................................................. 3,710 16 0.4
Killer Whale................................................. 656 20 3
Harbor Porpoise.............................................. 48,215 10 0.02
Bowhead Whale................................................ \2\ 15,750 200 1.3
Fin Whale.................................................... 5,700 5 0.09
Gray Whale................................................... 18,017 72 0.4
Humpback Whale............................................... 2,845 5 0.2
Minke Whale.................................................. 810-1,233 5 0.4-0.6
Bearded Seal................................................. \3\ 155,000 161 0.1
Ribbon Seal.................................................. 49,000 15 0.03
Ringed Seal.................................................. 208,000-252,000 818 0.3-0.4
Spotted Seal................................................. 141,479 231 0.2
----------------------------------------------------------------------------------------------------------------
\1\ Unless stated otherwise, abundance estimates are taken from Allen and Angliss (2012).
[[Page 12578]]
\2\ Estimate from George et al. (2004) with an annual growth rate of 3.4%.
\3\ Beringia Distinct Population Segment (NMFS, 2010).
Negligible Impact and Small Numbers Analysis and Preliminary
Determination
NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ``* * *
an impact resulting from the specified activity that cannot be
reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.'' In making a negligible impact determination,
NMFS considers a variety of factors, including but not limited to: (1)
The number of anticipated mortalities; (2) the number and nature of
anticipated injuries; (3) the number, nature, intensity, and duration
of Level B harassment; and (4) the context in which the takes occur.
No injuries or mortalities are anticipated to occur as a result of
COP's proposed Chukchi Sea exploratory drilling program, and none are
proposed to be authorized. Injury, serious injury, or mortality could
occur if there were a large or very large oil spill. However, as
discussed previously in this document, the likelihood of a spill is
extremely remote. COP has implemented many design and operational
standards to mitigate the potential for an oil spill of any size. NMFS
does not propose to authorize take from an oil spill, as it is not part
of the specified activity. Additionally, animals in the area are not
expected to incur hearing impairment (i.e., TTS or PTS) or non-auditory
physiological effects. Instead, any impact that could result from COP's
activities is most likely to be behavioral harassment and is expected
to be of limited duration. Although it is possible that some
individuals may be exposed to sounds from drilling operations more than
once, during the migratory periods it is less likely that this will
occur since animals will continue to move across the Chukchi Sea
towards their wintering grounds.
Bowhead and beluga whales are less likely to occur in the proposed
project area in July and August, as they are found mostly in the
Canadian Beaufort Sea at this time. The animals are more likely to
occur later in the season (mid-September through October), as they head
west towards Russia or south towards the Bering Sea. Additionally,
while bowhead whale tagging studies revealed that animals occurred in
the Lease Sale 193 area, a higher percentage of animals were found
outside of the Lease Sale 193 area in the fall (Quakenbush et al.,
2010). Bowhead whales are not known to feed in areas near COP's leases
in the Chukchi Sea. The closest primary feeding ground is near Point
Barrow, which is more than 200 mi (322 km) east of COP's Devils Paw
prospect. Therefore, if bowhead whales stop to feed near Point Barrow
during COP's proposed operations, the animals would not be exposed to
continuous sounds from the drill rig or support operations above 120 dB
or to impulsive sounds from the airguns above 160 dB, as those sound
levels only propagate 689 ft (210 m), 4.9 mi (7.9 km), and 3 mi (4.9
km), respectively. Additionally, the 120-dB radius for the airgun array
has been modeled to propagate 44 mi (71 km) from the source. Therefore,
sounds from the operations would not reach the feeding grounds near
Point Barrow. Gray whales occur in the northeastern Chukchi Sea during
the summer and early fall to feed. However, the primary feeding grounds
lies outside of the 120-dB and 160-dB ensonified areas from COP's
activities. While some individuals may swim through the area of active
drilling, it is not anticipated to interfere with their feeding in the
Chukchi Sea. Other cetacean species are much rarer in the proposed
project area. The exposure of cetaceans to sounds produced by
exploratory drilling operations (i.e., drill rig, DP, ice management,
and airgun operations) is not expected to result in more than Level B
harassment.
Few seals are expected to occur in the proposed project area, as
several of the species prefer more nearshore waters. Additionally, as
stated previously in this document, pinnipeds appear to be more
tolerant of anthropogenic sound, especially at lower received levels,
than other marine mammals, such as mysticetes. COP's proposed
activities would occur at a time of year when the ice seal species
found in the region are not molting, breeding, or pupping. Therefore,
these important life functions would not be impacted by COP's proposed
activities. The exposure of pinnipeds to sounds produced by COP's
proposed exploratory drilling operations in the Chukchi Sea is not
expected to result in more than Level B harassment of the affected
species or stock.
Of the 12 marine mammal species likely to occur in the proposed
drilling area, three are listed as endangered under the ESA--the
bowhead, humpback, and fin whales--and two are listed as threatened--
ringed and bearded seals. All five species are also designated as
``depleted'' under the MMPA. Despite these designations, the Bering-
Chukchi-Beaufort stock of bowheads has been increasing at a rate of
3.4% annually for nearly a decade (Allen and Angliss, 2012), even in
the face of ongoing industrial activity. Additionally, during the 2001
census, 121 calves were counted, which was the highest yet recorded.
The calf count provides corroborating evidence for a healthy and
increasing population (Allen and Angliss, 2011). An annual increase of
4.8% was estimated for the period 1987-2003 for North Pacific fin
whales. While this estimate is consistent with growth estimates for
other large whale populations, it should be used with caution due to
uncertainties in the initial population estimate and about population
stock structure in the area (Allen and Angliss, 2012). Zeribini et al.
(2006, cited in Allen and Angliss, 2012) noted an increase of 6.6% for
the Central North Pacific stock of humpback whales in Alaska waters.
There are currently no reliable data on trends of the ringed and
bearded seal stocks in Alaska. Certain stocks or populations of gray
and beluga whales and spotted seals are listed as endangered or are
proposed for listing under the ESA; however, none of those stocks or
populations occur in the proposed activity area. The ribbon seal is a
``species of concern.'' None of the other species that may occur in the
project area are listed as threatened or endangered under the ESA or
designated as depleted under the MMPA. There is currently no
established critical habitat in the proposed project area for any of
these 12 species.
Potential impacts to marine mammal habitat were discussed
previously in this document (see the ``Anticipated Effects on Habitat''
section). Although some disturbance is possible to food sources of
marine mammals, the impacts are anticipated to be minor. Based on the
vast size of the Arctic Ocean where feeding by marine mammals occurs
versus the localized area of the drilling program, any missed feeding
opportunities in the direct project area would be of little
consequence, as marine mammals would have access to other feeding
grounds.
The estimated takes proposed to be authorized represent less than
1.3% of the affected population or stock for all species. These
estimates represent the percentage of each species or stock that could
be taken by Level B behavioral
[[Page 12579]]
harassment if each animal is taken only once. The estimated take
numbers are likely somewhat of an overestimate. First, COP did not
account for potential overlap of some of the sound sources if they are
operating simultaneously. This leads to an overestimation of ensonified
area. Additionally, the mitigation and monitoring measures (described
previously in this document) proposed for inclusion in the IHA (if
issued) are expected to reduce even further any potential disturbance
to marine mammals. Last, some marine mammal individuals, including
mysticetes, have been shown to avoid the ensonified area around airguns
at certain distances (Richardson et al., 1999), and, therefore, some
individuals would not likely enter into the Level B harassment zones
for the various types of activities.
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the proposed mitigation and
monitoring measures, NMFS preliminarily finds that the proposed
exploration drilling program will result in the incidental take of
small numbers of marine mammals, by Level B harassment only, and that
the total taking from the drilling program will have a negligible
impact on the affected species or stocks.
Impact on Availability of Affected Species or Stock for Taking for
Subsistence Uses
Relevant Subsistence Uses
The disturbance and potential displacement of marine mammals by
sounds from drilling activities are the principal concerns related to
subsistence use of the area. Subsistence remains the basis for Alaska
Native culture and community. Marine mammals are legally hunted in
Alaskan waters by coastal Alaska Natives. In rural Alaska, subsistence
activities are often central to many aspects of human existence,
including patterns of family life, artistic expression, and community
religious and celebratory activities. Additionally, the animals taken
for subsistence provide a significant portion of the food that will
last the community throughout the year. The main species that are
hunted include bowhead and beluga whales, ringed, spotted, and bearded
seals, walruses, and polar bears. (As mentioned previously in this
document, both the walrus and the polar bear are under the USFWS'
jurisdiction.) The importance of each of these species varies among the
communities and is largely based on availability.
The subsistence communities in the Chukchi Sea that have the
potential to be impacted by COP's offshore drilling program include
Point Hope, Point Lay, Wainwright, Barrow, and possibly Kotzebue and
Kivalina (however, these two communities are much farther to the south
of the proposed project area). Point Lay, Wainwright, Point Hope,
Barrow, and Kivalina are approximately 90 mi (145 km), 120 mi (193 km),
175 mi (282 km), 200 mi (322 km), and 225 mi (362 km) from the Devils
Paw prospect, respectively. The communities of Gambell and Savoonga on
St. Lawrence Island also have the potential to be impacted if vessels
pass close by the island during times of active hunting.
(1) Bowhead Whales
Bowhead whale hunting is a key activity in the subsistence
economies of northwest Arctic communities. The whale harvests have a
great influence on social relations by strengthening the sense of
Inupiat culture and heritage in addition to reinforcing family and
community ties.
An overall quota system for the hunting of bowhead whales was
established by the International Whaling Commission (IWC) in 1977. The
quota is now regulated through an agreement between NMFS and the Alaska
Eskimo Whaling Commission (AEWC). The AEWC allots the number of bowhead
whales that each whaling community may harvest annually (USDOI/BLM,
2005). The annual take of bowhead whales has varied due to (a) changes
in the allowable quota level and (b) year-to-year variability in ice
and weather conditions, which strongly influence the success of the
hunt.
Bowhead whales migrate around northern Alaska twice each year,
during the spring and autumn, and are hunted in both seasons. Bowhead
whales are hunted from Barrow during the spring and the fall migration.
The spring hunt along Chukchi villages and at Barrow occurs after leads
open due to the deterioration of pack ice; the spring hunt typically
occurs from early April until the first week of June. From 1984-2009,
bowhead harvests by the villages of Wainwright, Point Hope, and Point
Lay occurred only between April 14 and June 24 and only between April
23 and June 15 in Barrow (George and Tarpley, 1986; George et al.,
1987, 1988, 1990, 1992, 1995, 1998, 1999, 2000; Philo et al., 1994;
Suydam et al., 1995b, 1996, 1997, 2001b, 2002, 2003, 2004, 2005b, 2006,
2007, 2008, 2009, 2010). Point Lay landed its first whale in more than
70 years during the spring hunt in 2009 and another whale during the
2011 spring hunt. COP will not mobilize and move into the Chukchi Sea
prior to July 1.
The fall migration of bowhead whales that summer in the eastern
Beaufort Sea typically begins in late August or September. Fall
migration into Alaskan waters is primarily during September and
October. In the fall, subsistence hunters use aluminum or fiberglass
boats with outboards. Hunters prefer to take bowheads close to shore to
avoid a long tow during which the meat can spoil, but Braund and
Moorehead (1995) report that crews may (rarely) pursue whales as far as
50 mi (80 km). The autumn bowhead hunt usually begins in Barrow in mid-
September and mainly occurs in the waters east and northeast of Point
Barrow. Fall bowhead whaling has not typically occurred in the villages
of Wainwright, Point Hope, and Point Lay in recent years. However, a
Wainwright whaling crew harvested the first fall bowhead whale in 90
years or more on October 8, 2010, and again landed a whale in October
2011. Because of changing ice conditions, there is the potential for
these villages to resume a fall bowhead harvest.
Barrow participates in a fall hunt each year. From 1984-2009,
Barrow whalers harvested bowhead whales between August 31 and October
29. While this time period overlaps with that of COP's proposed
operations, the drill sites are located more than 200 mi (322 km) west
of Barrow, so the whales would reach the Barrow hunting grounds before
entering the sound field of COP's operations. COP will be flying
helicopters out to the drillship for resupply missions. In the past 35
years, however, Barrow whaling crews have harvested almost all whales
in the Beaufort Sea to the east of Point Barrow (Suydam et al., 2008),
indicating that relatively little fall hunting occurs to the west where
the flight corridor is located. COP intends to base its flights out of
Wainwright.
(2) Beluga Whales
Beluga whales are available to subsistence hunters along the coast
of Alaska in the spring when pack-ice conditions deteriorate and leads
open up. Belugas may remain in coastal areas or lagoons through June
and sometimes into July and August. The community of Point Lay is
heavily dependent on the hunting of belugas in Kasegaluk Lagoon for
subsistence meat. From 1983-1992 the average annual harvest was
approximately 40 whales (Fuller and George, 1997). Point Hope residents
hunt beluga primarily in the lead system during the spring (late March
to early June) bowhead hunt but also in open-
[[Page 12580]]
water along the coastline in July and August. Belugas are harvested in
coastal waters near these villages, generally within a few miles from
shore.
In Wainwright and Barrow, hunters usually wait until after the
spring bowhead whale hunt is finished before turning their attention to
hunting belugas. The average annual harvest of beluga whales taken by
Barrow for 1962-1982 was five (MMS, 1996). The Alaska Beluga Whale
Committee (ABWC) recorded that 23 beluga whales had been harvested by
Barrow hunters from 1987 to 2002, ranging from 0 in 1987, 1988 and 1995
to the high of 8 in 1997 (Fuller and George, 1997; ABWC, 2002 cited in
USDOI/BLM, 2005). Barrow residents typically hunt for belugas between
Point Barrow and Skull Cliffs in the Chukchi Sea (primarily April-June)
and later in the summer (July-August) on both sides of the barrier
island in Elson Lagoon/Beaufort Sea (MMS, 2008). Harvest rates indicate
that the hunts are not frequent. Wainwright residents hunt beluga in
April-June in the spring lead system, but this hunt typically occurs
only if there are no bowheads in the area. Communal hunts for beluga
are conducted along the coastal lagoon system later in July-August.
COP's proposed exploration drilling activities take place well
offshore, far away from areas that are used for beluga hunting by the
Chukchi Sea communities. For vessel movements in nearshore areas, such
as the alternate drill rig staging area or presence of oil spill
response vessels, COP will consult with the communities on measures to
mitigate potential impacts on subsistence hunts.
(3) Ringed Seals
Ringed seals are hunted mainly in the Chukchi Sea from late March
through July; however, they can be hunted year-round. In winter, leads
and cracks in the ice off points of land and along the barrier islands
are used for hunting ringed seals. The average annual ringed seal
harvest was 49 seals in Point Lay, 86 in Wainwright, and 394 in Barrow
(Braund et al., 1993; USDOI/BLM, 2003, 2005). Although ringed seals are
available year-round, the planned activities will not occur during the
primary period when these seals are typically harvested (March-July).
Also, the activities will be largely in offshore waters where they will
not influence ringed seals in the nearshore areas where they are
hunted.
(4) Spotted Seals
Most subsistence harvest of the spotted seal is conducted by the
communities of Wainwright and Point Lay during the fall (September and
October), when spotted seals migrate back to their wintering habitats
in the Bering Sea (USDOI/BLM, 2003). Available maps of recent and past
subsistence use areas for spotted seals indicate harvest of this
species within 30-40 mi (48-64 km) of the coastline. Spotted seals are
also occasionally hunted in the area off Point Barrow and along the
barrier islands of Elson Lagoon to the east (USDOI/BLM, 2005). The
planned activities will remain offshore of the coastal harvest area of
these seals and should not conflict with harvest activities.
(5) Bearded Seals
Bearded seals, although generally not favored for their meat, are
important to subsistence activities in Barrow and Wainwright because of
their skins. Six to nine bearded seal hides are used by whalers to
cover each of the skin-covered boats traditionally used for spring
whaling. Because of their valuable hides and large size, bearded seals
are specifically sought. While bearded seals can be hunted year-round
in the Chukchi Sea, they are primarily harvested in spring during
breakup of the ice (Bacon et al., 2009). The animals inhabit the
environment around the ice floes in the drifting nearshore ice pack, so
hunting usually occurs from boats in the drift ice. Most bearded seals
are harvested in coastal areas inshore of the proposed exploration
drilling area, so no conflicts with the harvest of bearded seals are
expected.
Potential Impacts to Subsistence Uses
NMFS has defined ``unmitigable adverse impact'' in 50 CFR 216.103
as an impact resulting from the specified activity that is likely to
reduce the availability of the species to a level insufficient for a
harvest to meet subsistence needs by causing the marine mammals to
abandon or avoid hunting areas; directly displacing subsistence users;
or placing physical barriers between the marine mammals and the
subsistence hunters; and that cannot be sufficiently mitigated by other
measures to increase the availability of marine mammals to allow
subsistence needs to be met.
Noise and general activity during COP's proposed drilling program
have the potential to impact marine mammals hunted by Native Alaskans.
In the case of cetaceans, the most common reaction to anthropogenic
sounds (as noted previously in this document) is avoidance of the
ensonified area. In the case of bowhead whales, this often means that
the animals divert from their normal migratory path by several
kilometers. Helicopter activity also has the potential to disturb
cetaceans and pinnipeds by causing them to vacate the area.
Additionally, general vessel presence in the vicinity of traditional
hunting areas could negatively impact a hunt. Native knowledge
indicates that bowhead whales become increasingly ``skittish'' in the
presence of seismic noise. Whales are more wary around the hunters and
tend to expose a much smaller portion of their back when surfacing
(which makes harvesting more difficult). Additionally, natives report
that bowheads exhibit angry behaviors in the presence of seismic
activity, such as tail-slapping, which translate to danger for nearby
subsistence harvesters.
Plan of Cooperation (POC)
Regulations at 50 CFR 216.104(a)(12) require IHA applicants for
activities that take place in Arctic waters to provide a POC or
information that identifies what measures have been taken and/or will
be taken to minimize adverse effects on the availability of marine
mammals for subsistence purposes. COP has developed a Draft POC for its
2014 Chukchi Sea, Alaska, exploration drilling program to minimize any
adverse impacts on the availability of marine mammals for subsistence
uses. A copy of the POC was provided to NMFS with the IHA application
(see ADDRESSES for availability). COP began conducting meetings with
potentially affected communities in 2008. Exhibit 1 of COP's POC
contains a list of all meetings that have taken place through November
2012. Communities contacted include: Barrow, Kivalina, Kotzebue, Point
Hope, Point Lay, and Wainwright. COP also presented this program at the
2012 Open Water Meeting in Anchorage, Alaska, and plans to present at
the 2013 Open Water Meeting, scheduled for March 5-7, 2013, in
Anchorage, Alaska.
COP intends to meet with the North Slope Borough, Northwest Arctic
Borough, and Alaska Native marine mammal commissions before and after
operations. COP will also communicate throughout operations as needed.
In order to reduce impacts on subsistence hunts, COP intends to
implement a Communication Plan. COP will establish a central
communication station (Com-Station) located at Wainwright and
communication outposts in Point Hope, Poing Lay, and Barrow. The
Wainwright Com-Station will coordinate communication between the
drilling rig, marine vessels, aircraft, and the communication outposts
in each community as well as the
[[Page 12581]]
subsistence hunters in Wainwright. Personnel on the drilling rig or ice
management vessel will provide information to the Com-Center about the
timing and location of planned vessel activity. The communication
outposts will provide information to the Com-Station about the timing
and location of planned hunts. The Com-Station will relay information
and facilitate communication so that vessel activities can be modified
as necessary to prevent avoidable conflicts with subsistence hunting.
Communication outposts may also be established and manned in other
villages, such as Kivalina and Kotzebue, if subsistence activities
associated with those villages are occurring near the exploration
operations. A communication representative may also be present in Wales
and Savoonga during mobilization and demobilization activities if
subsistence activities are occurring.
The Com-Station and outposts will be staffed by Inupiat
communicators, if available. The duty of the Com-Station operator will
be to stay in communication with outposts and with hunters regarding
their subsistence hunting activities, and to relay information about
subsistence hunting locations and activities to the drilling rig and
marine vessels. The Com-Station operator will also provide the location
of the drilling rig and marine vessels to the subsistence hunters and
outposts.
The drill rig, ice management vessel, and monitoring vessel will
carry on-board an Inupiat Communicator, who will also serve as a PSO,
during the operating season. If a vessel that is part of the drilling
program is in the vicinity of a hunting area and the hunters have
launched their boats, the Inupiat Communicator's primary duty will be
to stay in communication with the hunters and relay information to the
vessel captain about hunting location, activities, timing, and overall
plans. At all other times, the Inupiat Communicator will be serving as
a PSO and will be responsible for monitoring for bowhead whales and
other marine mammals.
COP will plan vessel routes to minimize potential conflict with
marine mammals and subsistence activities related to marine mammals.
Vessels will avoid areas of active hunting through communication with
the established Com-Station by the Inupiat Communicator stationed on
the rig. Moreover, many of the mitigation measures described earlier in
this document (see the ``Proposed Mitigation'' section) will also help
reduce impacts to subsistence hunts and subsistence uses of marine
mammals. These include vessel operating measures when in the vicinity
of marine mammals and helicopter flight altitude restrictions.
Additionally, COP will not enter the Chukchi Sea prior to July 1 and
will begin demobilization by October 31 so as to transit out of the
Bering Strait no later than November 15.
Unmitigable Adverse Impact Analysis and Preliminary Determination
COP's drill sites are located more than 70 mi (113 km) from shore,
and some of the activities will not begin until after the close of
spring hunts. Seal hunts typically do not co-occur with COP's proposed
activities and those that do occur close to shore. COP will utilize
Com-Stations to avoid conflicts with active hunts. After the close of
the July beluga whale hunts in the Chukchi Sea villages, very little
whaling occurs in Wainwright, Point Hope, and Point Lay. Although the
fall bowhead whale hunt in Barrow will occur while COP is still
operating (mid- to late September to October), Barrow is located 200 mi
(322 km) east of the proposed drill sites. Based on these factors,
COP's Chukchi Sea survey is not expected to interfere with the fall
bowhead harvest in Barrow. In recent years, bowhead whales have
occasionally been taken in the fall by coastal villages along the
Chukchi coast, but the total number of these animals has been small.
Wainwright landed its first fall whale in more than 90 years in October
2010 and again landed a whale in October 2011. Hunters from the
northwest Arctic villages prefer to harvest whales within 50 mi (80 km)
so as to avoid long tows back to shore.
COP will also support village Com-Stations in the Arctic
communities and employ local advisors from the Chukchi Sea villages to
provide consultation and guidance regarding the whale migration and
subsistence hunt. They will provide advice to COP on ways to minimize
and mitigate potential impacts to subsistence resources during the
drilling season. Support activities, such as helicopter flights, could
impact nearshore subsistence hunts. However, COP will use flight paths
and agreed upon flight altitudes to avoid adverse impacts to hunts and
will communicate regularly with the Com-Station.
In the unlikely event of a major oil spill in the Chukchi Sea,
there could be major impacts on the availability of marine mammals for
subsistence uses. As discussed earlier in this document, the
probability of a major oil spill occurring over the life of the project
is low. Additionally, COP developed an OSRP, which is currently under
review by DOI and will also be reviewed by NOAA. COP has also
incorporated several mitigation measures into its operational design to
reduce further the risk of an oil spill. Based on the information
available, the proposed mitigation measures that COP will implement,
and the extremely low likelihood of a major oil spill occurring, NMFS
has preliminarily determined that COP's activities will not have an
unmitigable adverse impact on the availability of marine mammals for
subsistence uses.
Proposed Incidental Harassment Authorization
This section contains a draft of the IHA itself. The wording
contained in this section is proposed for inclusion in the IHA (if
issued).
(1) This Authorization is valid from July 1, 2014, through October
31, 2014.
(2) This Authorization is valid only for activities associated with
COP's 2014 Devils Paw, Chukchi Sea, exploration drilling program. The
specific areas where COP's exploration drilling program will be
conducted are within COP lease holdings in the Outer Continental Shelf
Lease Sale 193 area in the Chukchi Sea.
(3)(a) The incidental taking of marine mammals, by Level B
harassment only, is limited to the following species: bowhead whale;
gray whale; beluga whale; minke whale; fin whale; humpback whale;
killer whale; harbor porpoise; ringed seal; bearded seal; spotted seal;
and ribbon seal.
(3)(b) The taking by injury (Level A harassment), serious injury,
or death of any of the species listed in Condition 3(a) or the taking
of any kind of any other species of marine mammal is prohibited and may
result in the modification, suspension or revocation of this
Authorization.
(4) The authorization for taking by harassment is limited to the
following acoustic sources (or sources with comparable frequency and
intensity) and from the following activities:
(a) airgun array with a total discharge volume of 760 in\3\;
(b) continuous drill rig sounds during active drilling operations
and from support vessels in dynamic positioning mode; and
(c) vessel sounds generated during active ice management.
(5) The taking of any marine mammal in a manner prohibited under
this Authorization must be reported immediately to the Chief, Permits
and Conservation Division, Office of Protected Resources, NMFS or his
designee.
(6) The holder of this Authorization must notify the Chief of the
Permits and
[[Page 12582]]
Conservation Division, Office of Protected Resources, at least 48 hours
prior to the start of exploration drilling activities (unless
constrained by the date of issuance of this Authorization in which case
notification shall be made as soon as possible).
(7) General Mitigation and Monitoring Requirements: The Holder of
this Authorization is required to implement the following mitigation
and monitoring requirements when conducting the specified activities to
achieve the least practicable impact on affected marine mammal species
or stocks:
(a) All vessels shall reduce speed to at least 5 knots when within
300 yards (274 m) of whales. The reduction in speed will vary based on
the situation but must be sufficient to avoid interfering with the
whales. Those vessels capable of steering around such groups should do
so. Vessels may not be operated in such a way as to separate members of
a group of whales from other members of the group. For purposes of this
Authorization, a group is defined as being three or more whales
observed within a 547-yd (500-m) area and displaying behaviors of
directed or coordinated activity (e.g., group feeding);
(b) Avoid multiple changes in direction and speed when within 300
yards (274 m) of whales and also operate the vessel(s) to avoid causing
a whale to make multiple changes in direction;
(c) When weather conditions require, such as when visibility drops,
support vessels must reduce speed and change direction, as necessary
(and as operationally practicable), to avoid the likelihood of injury
to whales;
(d) Check the waters immediately adjacent to the vessel(s) to
ensure that no whales will be injured when the propellers are engaged;
(e) Vessels should remain as far offshore as weather and ice
conditions allow and at least 5 mi (8 km) offshore during transit;
(f) Aircraft shall not fly within 1,000 ft (305 m) of marine
mammals or below 1,500 ft (457 m) altitude (except during takeoffs,
landings, or in emergency situations) while over land or sea;
(g) Utilize NMFS-qualified, vessel-based Protected Species
Observers (PSOs) to visually watch for and monitor marine mammals near
the drill rig or ice management vessels during active drilling, dynamic
positioning, or airgun operations (from nautical twilight-dawn to
nautical twilight-dusk) and before and during start-ups of airguns day
or night. The vessels' crew shall also assist in detecting marine
mammals, when practicable. PSOs shall have access to reticle binoculars
(7x50 Fujinon) and big-eye binoculars (25x150). PSO shifts shall last
no longer than 4 hours at a time and shall not be on watch more than 12
hours in a 24-hour period. PSOs shall also make observations during
daytime periods when active operations are not being conducted for
comparison of animal abundance and behavior, when feasible;
(h) When a mammal sighting is made, the following information about
the sighting will be recorded:
(i) Species, group size, age/size/sex categories (if determinable),
behavior when first sighted and after initial sighting, heading (if
consistent), bearing and distance from the PSO, apparent reaction to
activities (e.g., none, avoidance, approach, paralleling, etc.),
closest point of approach, and behavioral pace;
(ii) Time, location, speed, activity of the vessel, sea state, ice
cover, visibility, and sun glare; and
(iii) The positions of other vessel(s) in the vicinity of the PSO
location.
(iv) The ship's position, speed of support vessels, and water
depth, sea state, ice cover, visibility, and sun glare will also be
recorded at the start and end of each observation watch, every 30
minutes during a watch, and whenever there is a change in any of those
variables.
(v) Altitude and position of the aircraft if sightings are made
during helicopter crew transfers.
(i) PSO teams shall consist of Inupiat observers and experienced
field biologists. An experienced field crew leader will supervise the
PSO team onboard the survey vessel. New observers shall be paired with
experienced observers to avoid situations where lack of experience
impairs the quality of observations;
(j) PSOs will complete a training session on marine mammal
monitoring, to be conducted shortly before the anticipated start of the
2014 open-water season.
(k) If there are Alaska Native PSOs, the PSO training that is
conducted prior to the start of the survey activities shall be
conducted with both Alaska Native PSOs and biologist PSOs being trained
at the same time in the same room. There shall not be separate training
courses for the different PSOs;
(l) PSOs shall be trained using visual aids (e.g., videos, photos)
to help them identify the species that they are likely to encounter in
the conditions under which the animals will likely be seen;
(m) Within safe limits, the PSOs should be stationed where they
have the best possible viewing. Viewing may not always be best from the
ship bridge, and in some cases may be best from higher positions with
less visual obstructions (e.g., flying bridge);
(n) PSOs should be instructed to identify animals as unknown where
appropriate rather than strive to identify a species if there is
significant uncertainty;
(o) PSOs should maximize their time with eyes on the water. This
may require new means of recording data (e.g., audio recorder) or the
presence of a data recorder so that the observers can simply relay
information to them; and
(p) PSOs should plot marine mammal sightings in near real-time for
their vessel into a GIS software program and relay information
regarding the animal(s)' position between platforms and vessels with
emphasis placed on relaying sightings with the greatest potential to
involve mitigation or reconsideration of the vessel's course.
(8) VSP Mitigation and Monitoring Measures: The Holder of this
Authorization is required to implement the following mitigation and
monitoring requirements when conducting the specified activities to
achieve the least practicable impact on affected marine mammal species
or stocks:
(a) PSOs shall conduct monitoring while the airgun array is being
deployed or recovered from the water;
(b) PSOs shall visually observe the entire extent of the exclusion
zone (EZ) (180 dB re 1 [mu]Pa [rms] for cetaceans and 190 dB re 1
[mu]Pa [rms] for pinnipeds) using NMFS-qualified PSOs, for at least 30
minutes (min) prior to starting the airgun array (day or night). If the
PSO finds a marine mammal within the EZ, COP must delay the seismic
survey until the marine mammal(s) has left the area. If the PSO sees a
marine mammal that surfaces then dives below the surface, the PSO shall
continue the watch for 30 min. If the PSO sees no marine mammals during
that time, they should assume that the animal has moved beyond the EZ.
If for any reason the entire radius cannot be seen for the entire 30
min period (i.e., rough seas, fog, darkness), or if marine mammals are
near, approaching, or in the EZ, the airguns may not be ramped-up. If
one airgun is already running at a source level of at least 180 dB re 1
[mu]Pa (rms), the Holder of this Authorization may start the second
airgun without observing the entire EZ for 30 min prior, provided no
marine mammals are known to be near the EZ;
(c) Establish and monitor a 180 dB re 1 [mu]Pa (rms) and a 190 dB
re 1 [mu]Pa (rms) EZ for marine mammals before the airgun array is in
operation; and a 180 dB re 1 [mu]Pa (rms) and a 190 dB re 1 [mu]Pa
(rms) EZ before a single airgun is in
[[Page 12583]]
operation. For purposes of the field verification tests, described in
condition 10(b)(i) below, the 180 dB radius for the airgun array is
predicted to be 0.6 mi (920 m) and the 190 dB radius for the airgun
array is predicted to be 525 ft (160 m). New radii will be used upon
completion of the field verification tests described in the Monitoring
Measures section below (condition 10(b)(i));
(d) Implement a ``ramp-up'' procedure when starting up at the
beginning of seismic operations, which means start the smallest gun
first and double the number of operating airguns at one-minute
intervals. During ramp-up, the PSOs shall monitor the EZ, and if marine
mammals are sighted, a power-down, or shut-down shall be implemented as
though the full array were operational. Therefore, initiation of ramp-
up procedures from shutdown requires that the PSOs be able to view the
full EZ;
(e) Power-down or shutdown the airgun(s) if a marine mammal is
detected within, approaches, or enters the relevant EZ. A shutdown
means all operating airguns are shutdown (i.e., turned off). A power-
down means reducing the number of operating airguns to a single
operating airgun, which reduces the EZ to the degree that the animal(s)
is no longer in or about to enter it;
(f) Following a power-down, if the marine mammal approaches the
smaller designated EZ, the airguns must then be completely shutdown.
Airgun activity shall not resume until the PSO has visually observed
the marine mammal(s) exiting the EZ and is not likely to return, or has
not been seen within the EZ for 15 min for species with shorter dive
durations (small odontocetes and pinnipeds) or 30 min for species with
longer dive durations (mysticetes);
(g) Following a power-down or shutdown and subsequent animal
departure, airgun operations may resume following ramp-up procedures
described in Condition 8(d) above;
(h) VSP surveys may continue into night and low-light hours if such
segment(s) of the survey is initiated when the entire relevant EZs are
visible and can be effectively monitored;
(i) No initiation of airgun array operations is permitted from a
shutdown position at night or during low-light hours (such as in dense
fog or heavy rain) when the entire relevant EZ cannot be effectively
monitored by the PSO(s) on duty; and
(j) When utilizing the mitigation airgun, use a reduced duty cycle
(e.g., 1 shot/min).
(9) Subsistence Mitigation Measures: To ensure no unmitigable
adverse impact on subsistence uses of marine mammals, the Holder of
this Authorization shall:
(a) Not enter the Chukchi Sea prior to July 1 to minimize effects
on spring and early summer whaling;
(b) Implement the Communication Plan before initiating exploration
drilling operations to coordinate activities with local subsistence
users and Village Whaling Associations in order to minimize the risk of
interfering with subsistence hunting activities;
(c) Establish Com-Stations and Com-Station outposts. The Com
Centers shall operate 24 hours/day during the 2012 bowhead whale hunt;
(d) Employ local Inupiat communicators from the Chukchi Sea
villages to provide consultation and guidance regarding the whale
migration and subsistence hunt;
(e) Not operate aircraft below 1,500 ft (457 m) unless engaged in
marine mammal monitoring, approaching, landing or taking off, or unless
engaged in providing assistance to a whaler or in poor weather (low
ceilings) or any other emergency situations; and
(f) Helicopters may not hover or circle above areas with groups of
whales or within 0.5 mi (800 m) of such areas.
(10) Monitoring Measures:
(a) Vessel-based Monitoring: The Holder of this Authorization shall
designate biologically-trained PSOs to be aboard the drill rig and ice
management vessels. The PSOs are required to monitor for marine mammals
in order to implement the mitigation measures described in conditions 7
and 8 above;
(b) Acoustic Monitoring:
(i) Field Source Verification: the Holder of this Authorization is
required to conduct sound source verification tests for the drill rig,
support vessels in DP mode, and the airgun array. Sound source
verification shall consist of distances where broadside and endfire
directions at which broadband received levels reach 190, 180, 170, 160,
and 120 dB re 1 [mu]Pa (rms) for all active acoustic sources that may
be used during the activities. For the airgun array, the configurations
shall include at least the full array and the operation of a single
source that will be used during power downs. Initial results must be
provided to NMFS within 120 hours of completing the analysis.
(ii) The Holder of this Authorization shall deploy acoustic
recorders in the U.S. Chukchi Sea in order to gain information on the
distribution of marine mammals in the region. To the extent
practicable, this program must be implemented as detailed in the 4MP.
(11) Reporting Requirements: The Holder of this Authorization is
required to:
(a) Submit a sound source verification report to NMFS with the
results for the drill rig, support vessels (including in DP mode), and
the airguns. The reports should report down to the 120-dB radius in 10-
dB increments;
(b) Submit daily PSO logs to NMFS;
(c) Submit a draft report on all activities and monitoring results
to the Office of Protected Resources, NMFS, within 90 days of the
completion of the exploration drilling program. This report must
contain and summarize the following information:
(i) summaries of monitoring effort (e.g., total hours, total
distances, and marine mammal distribution through the study period,
accounting for sea state and other factors affecting visibility and
detectability of marine mammals);
(ii) analyses of the effects of various factors influencing
detectability of marine mammals (e.g., sea state, number of observers,
and fog/glare);
(iii) species composition, occurrence, and distribution of marine
mammal sightings, including date, water depth, numbers, age/size/gender
categories (if determinable), group sizes, and ice cover;
(iv) sighting rates of marine mammals during periods with and
without exploration drilling activities (and other variables that could
affect detectability), such as: (A) Initial sighting distances versus
drilling state; (B) closest point of approach versus drilling state;
(C) observed behaviors and types of movements versus drilling state;
(D) numbers of sightings/individuals seen versus drilling state; (E)
distribution around the survey vessel versus drilling state; and (F)
estimates of take by harassment;
(v) Reported results from all hypothesis tests should include
estimates of the associated statistical power when practicable;
(vi) Estimate and report uncertainty in all take estimates.
Uncertainty could be expressed by the presentation of confidence
limits, a minimum-maximum, posterior probability distribution, etc.;
the exact approach would be selected based on the sampling method and
data available;
(vii) The report should clearly compare authorized takes to the
level of actual estimated takes;
(viii) Sampling of the relative near-field around operations should
be corrected for effort to provide the best possible estimates of
marine mammals in EZs and exposure zones; and
[[Page 12584]]
(ix) If, after the independent monitoring plan peer review changes
are made to the monitoring program, those changes must be detailed in
the report.
(d) The draft report will be subject to review and comment by NMFS.
Any recommendations made by NMFS must be addressed in the final report
prior to acceptance by NMFS. The draft report will be considered the
final report for this activity under this Authorization if NMFS has not
provided comments and recommendations within 90 days of receipt of the
draft report.
(12)(a) In the unanticipated event that the drilling program
operation clearly causes the take of a marine mammal in a manner
prohibited by this Authorization, such as an injury (Level A
harassment), serious injury or mortality (e.g., ship-strike, gear
interaction, and/or entanglement), COP shall immediately take steps to
cease operations and immediately report the incident to the Chief of
the Permits and Conservation Division, Office of Protected Resources,
NMFS, or his designee by phone or email, the Alaska Regional Office,
and the Alaska Regional Stranding Coordinators. The report must include
the following information: (i) Time, date, and location (latitude/
longitude) of the incident; (ii) the name and type of vessel involved;
(iii) the vessel's speed during and leading up to the incident; (iv)
description of the incident; (v) status of all sound source use in the
24 hours preceding the incident; (vi) water depth; (vii) environmental
conditions (e.g., wind speed and direction, Beaufort sea state, cloud
cover, and visibility); (viii) description of marine mammal
observations in the 24 hours preceding the incident; (ix) species
identification or description of the animal(s) involved; (x) the fate
of the animal(s); (xi) and photographs or video footage of the animal
(if equipment is available).
Activities shall not resume until NMFS is able to review the
circumstances of the prohibited take. NMFS shall work with COP to
determine what is necessary to minimize the likelihood of further
prohibited take and ensure MMPA compliance. COP may not resume their
activities until notified by NMFS via letter, email, or telephone.
(b) In the event that COP discovers an injured or dead marine
mammal, and the lead PSO determines that the cause of the injury or
death is unknown and the death is relatively recent (i.e., in less than
a moderate state of decomposition as described in the next paragraph),
COP will immediately report the incident to the Chief of the Permits
and Conservation Division, Office of Protected Resources, NMFS, by
phone or email, the Alaska Regional Office, and the NMFS Alaska
Stranding Hotline and/or by email to the Alaska Regional Stranding
Coordinators. The report must include the same information identified
in Condition 12(a) above. Activities may continue while NMFS reviews
the circumstances of the incident. NMFS will work with COP to determine
whether modifications in the activities are appropriate.
(c) In the event that COP discovers an injured or dead marine
mammal, and the lead PSO determines that the injury or death is not
associated with or related to the activities authorized in Condition 2
of this Authorization (e.g., previously wounded animal, carcass with
moderate to advanced decomposition, or scavenger damage), COP shall
report the incident to the Chief of the Permits and Conservation
Division, Office of Protected Resources, NMFS, by phone or email and
the NMFS Alaska Stranding Hotline and/or by email to the Alaska
Regional Stranding Coordinators, within 24 hours of the discovery. COP
shall provide photographs or video footage (if available) or other
documentation of the stranded animal sighting to NMFS and the Marine
Mammal Stranding Network. Activities may continue while NMFS reviews
the circumstances of the incident.
(13) Activities related to the monitoring described in this
Authorization do not require a separate scientific research permit
issued under section 104 of the Marine Mammal Protection Act.
(14) The Plan of Cooperation outlining the steps that will be taken
to cooperate and communicate with the native communities to ensure the
availability of marine mammals for subsistence uses must be
implemented.
(15) COP is required to comply with the Terms and Conditions of the
Incidental Take Statement (ITS) corresponding to NMFS's Biological
Opinion issued to NMFS's Office of Protected Resources.
(16) A copy of this Authorization and the ITS must be in the
possession of all contractors and PSOs operating under the authority of
this Incidental Harassment Authorization.
(17) Penalties and Permit Sanctions: Any person who violates any
provision of this Incidental Harassment Authorization is subject to
civil and criminal penalties, permit sanctions, and forfeiture as
authorized under the MMPA.
(18) This Authorization may be modified, suspended or withdrawn if
the Holder fails to abide by the conditions prescribed herein or if the
authorized taking is having more than a negligible impact on the
species or stock of affected marine mammals, or if there is an
unmitigable adverse impact on the availability of such species or
stocks for subsistence uses.
Endangered Species Act (ESA)
There are three marine mammal species listed as endangered under
the ESA with confirmed or possible occurrence in the proposed project
area: the bowhead, humpback, and fin whales. There are two marine
mammal species listed as threatened under the ESA with confirmed
occurrence in the proposed project area: ringed and bearded seals.
NMFS' Permits and Conservation Division will initiate consultation with
NMFS' Endangered Species Division under section 7 of the ESA on the
issuance of an IHA to COP under section 101(a)(5)(D) of the MMPA for
this activity. Consultation will be concluded prior to a determination
on the issuance of an IHA.
National Environmental Policy Act (NEPA)
NMFS is currently preparing an Environmental Assessment (EA),
pursuant to NEPA, to determine whether the issuance of an IHA to COP
for its 2014 drilling activities may have a significant impact on the
human environment. NMFS expects to release a draft of the EA for public
comment and will inform the public through the Federal Register and
posting on our Web site once a draft is available (see ADDRESSES).
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
authorize the take of marine mammals incidental to COP for its 2014
open-water exploration drilling program, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated.
Dated: February 12, 2013.
Helen M. Golde,
Acting Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 2013-03681 Filed 2-21-13; 8:45 am]
BILLING CODE 3510-22-P