[Federal Register Volume 79, Number 73 (Wednesday, April 16, 2014)]
[Notices]
[Pages 21522-21550]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2014-08534]
[[Page 21521]]
Vol. 79
Wednesday,
No. 73
April 16, 2014
Part II
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 a Geohazard Survey in the Beaufort Sea,
Alaska; Notice
Federal Register / Vol. 79, No. 73 / Wednesday, April 16, 2014 /
Notices
[[Page 21522]]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XD229
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Geohazard Survey in the Beaufort
Sea, Alaska
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 has received an application from BP Exploration (Alaska)
Inc. (BP) for an Incidental Harassment Authorization (IHA) to take
marine mammals, by harassment, incidental to conducting a shallow
geohazard survey in Foggy Island Bay, Beaufort Sea, Alaska, during the
2014 open water season. Pursuant to the Marine Mammal Protection Act
(MMPA), NMFS is requesting comments on its proposal to issue an IHA to
BP to incidentally take, by Level B harassment only, marine mammals
during the specified activity.
DATES: Comments and information must be received no later than May 16,
2014.
ADDRESSES: Comments on the application should be addressed to Jolie
Harrison, Supervisor, Incidental Take Program, 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
(e.g., name, address) voluntarily submitted by the commenter may be
publicly accessible. Do not submit Confidential Business Information or
otherwise sensitive or protected information.
An electronic copy of the application containing a list of the
references 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, other means of
effecting the least practicable impact on the species or stock and its
habitat, 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.''
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
On February 4, 2014, NMFS received an application from BP for the
taking of marine mammals incidental to conducting a shallow geohazard
survey. NMFS determined that the application was adequate and complete
on March 6, 2014.
BP proposes to conduct a shallow geohazard survey in Federal and
state waters of Foggy Island Bay in the Beaufort Sea during the open-
water season of 2014. The proposed activity would occur between July 1
and September 30; however, airgun and other sound source equipment
operations would cease on August 25. The following specific aspects of
the proposed activity are likely to result in the take of marine
mammals: airguns and scientific sonars/devices. Take, by Level B
harassment only, of 9 marine mammal species is anticipated to result
from the specified activity.
Description of the Specified Activity
Overview
BP's proposed shallow geohazard survey would consist of two phases:
a site survey and a sonar survey. During the first phase, the Site
Survey, the emphasis is on obtaining shallow geohazard data using an
airgun array and a towed streamer. During the second phase, the Sonar
Survey, data will be acquired both in the Site Survey location and
subsea pipeline corridor area (see Figure 1 in BP's application) using
the multibeam echosounder, sidescan sonar, subbottom profiler, and the
magnetometer. The total discharge volume of the airgun array will not
exceed 30 cubic inches (in\3\). The program is proposed to be conducted
during the 2014 open-water season.
The purpose of the proposed shallow geohazard survey is to evaluate
development of the Liberty field. The Liberty reservoir is located in
federal waters in Foggy Island Bay about 8 miles (mi) east of the
Endicott Satellite Drilling Island. The project's preferred alternative
is to build a gravel island situated over the reservoir. In support of
the preferred alternative, a Site Survey is planned with an emphasis on
obtaining two-dimensional high-resolution (2DHR) shallow geohazard data
using an airgun array and a towed streamer. Additional infrastructure
required for the preferred alternative would include a subsea pipeline.
A Sonar Survey, using multibeam echosounder, sidescan sonar, subbottom
profiler, and magnetometer is proposed over the Site Survey location
and subsea pipeline corridor area. The purpose of this proposed survey
is to evaluate the existence and location of archaeological resources
and potential geologic hazards on the seafloor and in the shallow
subsurface.
Dates and Duration
The planned start date is approximately July 1, 2014, with data
[[Page 21523]]
acquisition beginning when open water conditions allow. The survey is
expected to take approximately 20 days to complete, not including
weather downtime. Each phase of the survey (i.e., site survey and sonar
survey) has an expected duration of 7.5 days based on a 24-hour
workday. Between the first and second phase, the operations will be
focused on changing equipment for about 5 days (i.e., no active sound
sources would be used to acquire data during this time). To limit
potential impacts to the bowhead whale fall migration and subsistence
hunting, airgun and sonar operations will cease by midnight on August
25. Demobilization of equipment would continue after airgun and sonar
operations end but would be completed by September 30. Therefore, the
proposed dates for the IHA (if issued) are July 1 through September 30,
2014.
Specified Geographic Region
The proposed shallow geohazards survey would occur in Federal and
state waters of Foggy Island Bay in the Beaufort Sea, Alaska. The
project area lies mainly within the Liberty Unit but also includes
portions of the Duck Island Unit, as well as non-unit areas. Figure 1
in BP's application outlines the proposed survey acquisition areas,
including proposed boundaries for the two phases of the project. The
Phase 1 Site Survey, focused on obtaining shallow geohazard data using
an airgun array and towed streamer, will occur within approximately 12
mi\2\. The Phase 2 Sonar Survey will occur over the Site Survey area
and over approximately 5 mi\2\ within the 29 mi\2\ area identified in
Figure 1 of BP's application. Water depth in this area ranges from
about 2-24 ft. Activity outside the area delineated in Figure 1 of BP's
application may include vessel turning while using airguns, vessel
transit, and other vessel movements for project support and logistics.
The approximate boundaries of the two survey areas are between
70[deg]14'10'' N. and 70[deg]20'20'' N. and between 147[deg]29'05'' W.
and 148[deg]52'30'' W.
Detailed Description of Activities
The activities associated with the proposed shallow geohazard
survey include vessel mobilization, navigation and data management,
housing and logistics, and data acquisition.
1. Vessel Mobilization
One vessel will be used for the geohazard survey. The proposed
survey vessel (R/V Thunder or equivalent) is about 70 x 20 ft in size.
This vessel will be transported to the North Slope by truck and
prepared and launched at West Dock or Endicott. Vessel preparation
includes the assembly of navigation, acoustic, and safety equipment.
Initial fueling and stocking of recording equipment will also be part
of the vessel preparations. Once assembled, the navigation and acoustic
systems will be tested at West Dock or at the project site.
2. Navigation and Data Management
The vessel will be equipped with Differential Global Navigation
Satellite System receivers capable of observing dual constellations and
backup. Corrected positions will be provided via a precise point
positioning solution. A kinematic base station will be kept at the
housing facilities in Deadhorse to mitigate against the inability to
acquire a precise point positioning signal. Tidal corrections will be
determined through Global Navigation Satellite System computation,
comparison with any local tide gauges, and, if available, with tide
gauges operated by other projects.
A navigation software package will display known obstructions,
islands, and identified areas of sensitivity. The software will also
show the pre-determined source line positions within the two survey
areas. The information will be updated as necessary to ensure required
data coverage. The navigation software will also record all measured
equipment offsets and corrections and vessel and equipment position at
a frequency of no less than once per 5 seconds for the duration of the
project.
3. Housing and Logistics
Approximately 20 people will be involved in the operation. Most of
the crew will be accommodated at existing camps, and some crew will be
housed on the vessel. Support activities, such as crew transfers and
vessel re-supply are primarily planned to occur at Endicott and West
Dock. However, support activities may also occur at other nearby vessel
accessible locations if needed (e.g., East Dock). Equipment staging and
onshore support will primarily occur at West Dock but may also take
place at other existing road-accessible pads within the Prudhoe Bay
Unit area as necessary. For protection from weather, the vessel may
anchor near West Dock, near the barrier islands, or other near shore
locations.
4. Data Acquisition
Equipment proposed for use during the proposed shallow geohazard
survey includes airgun, multibeam echosounder, sidescan sonar,
subbottom profiler, and a marine magnetometer. Details related to data
acquisition are summarized next.
Survey Design: One vessel will be used for the proposed survey. The
proposed vessel (R/V Thunder or equivalent) is about 70 x 20 ft in
size. The airgun and streamer, sidescan sonar, and magnetometer will be
deployed from the vessel. The multibeam echosounder and subbottom
profiler will be hull-mounted. No equipment will be placed on the sea
floor as part of survey activities.
The survey will acquire data in two phases. During the first phase
the emphasis is on obtaining shallow geohazard data in the Site Survey
area (see Figure 1 in BP's application) using an airgun array and a
towed streamer. During the second phase data will be acquired in both
the Site Survey and Sonar Survey areas (see Figure 1 in BP's
application) using the multibeam echosounder, sidescan sonar, subbottom
profiler, and the magnetometer. Each phase has an expected duration of
about 7.5 days, based on a 24-hour workday. Between the first and
second phase the operations will be focused on changing equipment for
about 5 days.
2DHR Seismic: High-resolution seismic data acquisition will only
take place during Phase 1 in the Site Survey area. The 2DHR seismic
source will consist of one of two potential arrays, each with a
discharge volume of 30 in\3\ and containing multiple airguns. The first
array option will have three 10 in\3\ airguns, and the other array
option will have a 20 in\3\ and a 10 in\3\ airgun. Table 1 in this
document and BP's application summarizes airgun array specifics for
each option. A 5 in\3\ airgun will be utilized as the mitigation gun.
The tow depth will be about 3 ft.
The receivers will be placed on a streamer that is towed behind the
source vessel. The streamer will be about 984 ft in length and will
contain 48 receivers at about 20 ft spacing.
Seismic data will be acquired on two grids. Grid 1 will contain
lines spaced at 492 ft with perpendicular 984 ft spaced lines. Grid 2
will contain approximately 65 ft spaced lines. The total line length of
both grids will be about 342 miles.
The vessel will travel with a speed of approximately 3-4 knots. The
seismic pulse interval is 20.5 ft, which means a shot every 3 to 4
seconds.
[[Page 21524]]
Table 1--Proposed 30 in\3\ Airgun Array Configurations and Source
Signatures as Predicted by the Gundalf Airgun Array Model for 1 m Depth
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30 in\3\ Array 30 in\3\ Array
Array specifics option 1 option 2
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Number of guns.............. Three 2000 psi Two 2000 psi sleeve
sleeve airguns (3 x airguns (1 x 20
10 in\3\). in\3\, 1 x 10
in\3\).
Zero to peak................ 4.89 bar-m (~234 dB 3.62 bar-m (~231 dB
re [micro]Pa @1 m). re 1 [micro]Pa @1
m).
Peak to peak................ 9.75 bar-m (~240 dB 7.04 bar-m (~237 dB
re [micro]Pa @1 m). re 1 [micro]Pa @1
m).
RMS pressure................ 0.28 bar-m (~209 dB 0.22 bar-m (~207 dB
re [micro]Pa @1 m). re 1 [micro]Pa @1
m).
Dominant frequencies........ About 20-300 Hz..... About 20-300 Hz.
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Multibeam Echosounder and Sidescan Sonar: A multibeam echosounder
and sidescan sonar will be used to obtain high accuracy information
regarding bathymetry and isonification of the seafloor. For accurate
object detection, a side scan sonar survey is required to complement a
multibeam echosounder survey.
The proposed multibeam echosounder operates at a root mean squared
(rms) source level of approximately 220 dB re 1 [mu]Pa at 1 m. The
multibeam echosounder emits high frequency energy in a fan-shaped
pattern of equidistant or equiangular beam spacing. The beam width of
the emitted sound energy in the along track direction is 2 degrees at
200 kilohertz (kHz) and 1 degree at 400 kHz, while the across track
beam width is 1 degree at 200 kHz and 0.5 degrees at 400 kHz (see Table
2 in BP's application and this document). The maximum ping rate of the
multibeam echosounder is 60 Hz.
The proposed sidescan sonar system will operate at about 100 kHz
(120 kHz to 135 kHz) and 400 kHz (400 kHz to 450 kHz). The estimated
rms source level is approximately 215 dB re 1 [mu]Pa at 1 m (Table 2).
The sound energy is emitted in a narrow fan-shaped pattern, with a
horizontal beam width of 1.5 degrees for 100 kHz and 0.4 degrees at 400
kHz, with a vertical beam height of 50 degrees. The maximum ping rate
of the sidescan sonar is 30 Hz.
Data acquisition with the multibeam echosounder and sidescan sonar
data will take place along all grids in the Sonar Survey area.
Additional multibeam echosounder and sidescan sonar infill lines will
be added to obtain 150% coverage over certain areas.
In addition, BP may conduct a strudel scour survey in the
Kadleroshilik and Sagavanirktok River overflood areas for about 3 days,
depending on results from reconnaissance flights in June. This data
would be collected from a separate vessel equipped with a multibeam
echosounder and sidescan sonar. These units would operate at a
frequency of about 400 kHz. Because this operating frequency is outside
the hearing range of marine mammals, the strudel scour survey is not
part of BP's IHA application and is not analyzed further.
Subbottom Profiler: The purpose of the subbottom profiler is to
provide an accurate digital image of the shallow sub-surface sea
bottom, below the mud line. The proposed system emits energy in the
frequency bands of 2 to 16 kHz (Table 2). The beam width is 15 to 24
degrees, depending on the center frequency. Typical pulse rate is
between 3 and 6 Hz. Subbottom profiler data will be acquired
continuously along all grids during Phase 2 of the operations (i.e.,
after 2DHR seismic data has been obtained).
Magnetometer: A marine magnetometer will be used for the detection
of magnetic deflection generated by geologic features, and buried or
exposed ferrous objects, which may be related to archaeological
artifacts or modern man-made debris. The magnetometer will be towed at
a sufficient distance behind the vessel to avoid data pollution by the
vessel's magnetic properties. Magnetometers measure changes in magnetic
fields over the seabed and do not produce sounds. Therefore, this piece
of equipment is not anticipated to result in the take of marine mammals
and is not analyzed further in this document.
Table 2--Source Characteristics of the Proposed Geophysical Survey Equipment of the Liberty Geohazard Survey
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Along track Across track RMS sound pressure
Equipment Operating frequency beam width beam width level
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Multibeam echosounder............. 200-400 kHz.......... 1-2[deg] 0.5-1[deg] ~220 dB re 1 [mu]Pa
@1m.
Sidescan sonar.................... 120-135 kHz.......... 1.5[deg] 50[deg] ~215 dB re 1 [mu]Pa
400-450 kHz.......... 0.4[deg] 50[deg] @1m.
Subbottom profiler................ 2-16 kHz............. 15-24[deg] 15-24[deg] ~216 dB re 1 [mu]Pa
@1m.
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Description of Marine Mammals in the Area of the Specified Activity
The Beaufort Sea supports a diverse assemblage of marine mammals.
Table 3 lists the 12 marine mammal species under NMFS jurisdiction with
confirmed or possible occurrence in the proposed project area.
Table 3--Marine Mammal Species With Confirmed or Possible Occurrence in the Proposed Seismic Survey Area
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Common name Scientific name Status Occurrence Seasonality Range Abundance
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Odontocetes..................... Delphinapterus ................... Common............ Mostly spring and Russia to Canada.. 39,258
Beluga whale (Beaufort Sea leucas. fall with some in
stock). summer.
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Killer whale.................... Orcinus orca....... ................... Occasional/ Mostly summer and California to 552
Extralimital. early fall. Alaska.
Harbor porpoise................. Phocoena phocoena.. ................... Occasional/ Mostly summer and California to 48,215
Extralimital. early fall. Alaska.
Narwhal......................... Monodon monoceros.. ................... .................. .................. .................. 45,358
Mysticetes...................... Balaena mysticetus. Endangered; Common............ Mostly spring and Russia to Canada.. 16,892
Bowhead whale................... Depleted. fall with some in
summer.
Gray whale...................... Eschrichtius ................... Somewhat common... Mostly summer..... Mexico to the U.S. 19,126
robustus. Arctic Ocean.
Minke whale..................... Balaenoptera ................... .................. .................. .................. 810-1,003
acutorostrata.
Humpback whale (Central North Megaptera Endangered; .................. .................. .................. 21,063
Pacific stock). novaeangliae. Depleted.
Pinnipeds....................... Erigathus barbatus. Threatened; Common............ Spring and summer. Bering, Chukchi, 155,000
Bearded seal (Beringia distinct Depleted. and Beaufort Seas.
population segment).
Ringed seal (Arctic stock)...... Phoca hispida...... Threatened; Common............ Year round........ Bering, Chukchi, 300,000
Depleted. and Beaufort Seas.
Spotted seal.................... Phoca largha....... ................... Common............ Summer............ Japan to U.S. 141,479
Arctic Ocean.
Ribbon seal..................... Histriophoca Species of concern. Occasional........ Summer............ Russia to U.S. 49,000
fasciata. Arctic Ocean.
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Endangered, threatened, or species of concern under the Endangered Species Act (ESA); Depleted under the MMPA.
The highlighted (grayed out) species in Table 3 are so rarely
sighted in the central Alaskan Beaufort Sea that their presence in the
proposed project area, and therefore take, is unlikely. Minke whales
are relatively common in the Bering and southern Chukchi seas and have
recently also been sighted in the northeastern Chukchi Sea (Aerts et
al., 2013; Clarke et al., 2013). Minke whales are rare in the Beaufort
Sea. They have not been reported in the Beaufort Sea during the Bowhead
Whale Aerial Survey Project/Aerial Surveys of Arctic Marine Mammals
(BWASP/ASAMM) surveys (Clarke et al., 2011, 2012; 2013; Monnet and
Treacy, 2005), and there was only one observation in 2007 during
vessel-based surveys in the region (Funk et al., 2010). Humpback whales
have not generally been found in the Arctic Ocean. However, subsistence
hunters have spotted humpback whales in low numbers around Barrow, and
there have been several confirmed sightings of humpback whales in the
northeastern Chukchi Sea in recent years (Aerts et al., 2013; Clarke et
al., 2013). The first confirmed sighting of a humpback whale in the
Beaufort Sea was recorded in August 2007 (Hashagen et al., 2009) when a
cow and calf were observed 54 mi east of Point Barrow. No additional
sightings have been documented in the Beaufort Sea. Narwhal are common
in the waters of northern Canada, west Greenland, and in the European
Arctic, but rarely occur in the Beaufort Sea (COSEWIC, 2004). Only a
handful of sightings have occurred in Alaskan waters (Allen and
Angliss, 2013). These three species are not considered further in this
proposed IHA notice. Both the walrus and the polar bear could occur in
the U.S. Beaufort Sea; however, these species are managed by the U.S.
Fish and Wildlife Service (USFWS) and are not considered further in
this Notice of Proposed IHA.
The Beaufort Sea is a main corridor of the bowhead whale migration
route. The main migration periods occur in spring from April to June
and in fall from late August/early September through October to early
November. During the fall migration, several locations in the U.S.
Beaufort Sea serve as feeding grounds for bowhead whales. Small numbers
of bowhead whales that remain in the U.S. Arctic Ocean during summer
also feed in these areas. The U.S. Beaufort Sea is not a main feeding
or calving area for any other cetacean species. Ringed seals breed and
pup in the Beaufort Sea; however, this does not occur during the summer
or early fall. Further information on the biology and local
distribution of these species can be found in BP's application (see
ADDRESSES) and the NMFS Marine Mammal Stock Assessment Reports, which
are available online at: http://www.nmfs.noaa.gov/pr/species/.
Potential Effects of the Specified Activity on Marine Mammals
This section includes a summary and discussion of the ways that the
types of stressors associated with the specified activity (e.g.,
seismic airgun, sidescan sonar, subbottom profiler, vessel movement)
have been observed to or are thought to impact marine mammals. This
section may include a discussion of known effects that do not rise to
the level of an MMPA take (for example, with acoustics, we may include
a discussion of studies that showed animals not reacting at all to
sound or exhibiting barely measurable avoidance). The discussion may
also include reactions that we consider to rise to the level of a take
and those that we do not consider to rise to the level of a take. This
section is intended as a background of potential effects and does not
consider either the specific manner in which this activity will be
carried out or the mitigation that will be implemented or how either of
those will shape the anticipated impacts from this specific activity.
The ``Estimated Take by Incidental Harassment'' section later in this
document will include a
[[Page 21526]]
quantitative analysis of the number of individuals that are expected to
be taken by this activity. The ``Negligible Impact Analysis'' section
will include the analysis of how this specific activity will impact
marine mammals and will consider the content of this section, the
``Estimated Take by Incidental Harassment'' section, the ``Mitigation''
section, and the ``Anticipated Effects on Marine Mammal Habitat''
section to draw conclusions regarding the likely impacts of this
activity on the reproductive success or survivorship of individuals and
from that on the affected marine mammal populations or stocks.
Background on Sound
Sound is a physical phenomenon consisting of minute vibrations that
travel through a medium, such as air or water, and is generally
characterized by several variables. Frequency describes the sound's
pitch and is measured in hertz (Hz) or kilohertz (kHz), while sound
level describes the sound's intensity and is measured in decibels (dB).
Sound level increases or decreases exponentially with each dB of
change. The logarithmic nature of the scale means that each 10-dB
increase is a 10-fold increase in acoustic power (and a 20-dB increase
is then a 100-fold increase in power). A 10-fold increase in acoustic
power does not mean that the sound is perceived as being 10 times
louder, however. Sound levels are compared to a reference sound
pressure (micro-Pascal) to identify the medium. For air and water,
these reference pressures are ``re: 20 [micro]Pa'' and ``re: 1
[micro]Pa,'' respectively. Root mean square (RMS) is the quadratic mean
sound pressure over the duration of an impulse. RMS is calculated by
squaring all of the sound amplitudes, averaging the squares, and then
taking the square root of the average (Urick, 1975). RMS accounts for
both positive and negative values; squaring the pressures makes all
values positive so that they may be accounted for in the summation of
pressure levels (Hastings and Popper, 2005). This measurement is often
used in the context of discussing behavioral effects, in part, because
behavioral effects, which often result from auditory cues, may be
better expressed through averaged units rather than by peak pressures.
Acoustic Impacts
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
30 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;
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;
Phocid pinnipeds in Water: Functional hearing is estimated
to occur between approximately 75 Hz and 100 kHz; and
Otariid pinnipeds in Water: Functional hearing is
estimated to occur between approximately 100 Hz and 40 kHz.
As mentioned previously in this document, nine marine mammal
species (five cetaceans and four phocid pinnipeds) may occur in the
proposed seismic survey area. Of the five cetacean species likely to
occur in the proposed project area and for which take is requested, two
are classified as low-frequency cetaceans (i.e., bowhead and gray
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). A species functional
hearing group is a consideration when we analyze the effects of
exposure to sound on marine mammals.
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). 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). The airgun arrays used in the Weir (2008)
study were much larger than the array proposed for use during this
proposed survey (total discharge volume of 30 in\3\). 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. (1995) found that vessel noise does not seem to strongly affect
pinnipeds that are already in the water. Richardson et al. (1995) 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.
2. Masking
Masking is the obscuring of sounds of interest by other sounds,
often at similar frequencies. Marine mammals use acoustic signals for a
variety of purposes, which differ among species, but include
communication between individuals, navigation, foraging, reproduction,
avoiding predators, and learning about their environment (Erbe and
Farmer, 2000; Tyack, 2000). Masking, or auditory interference,
generally occurs when sounds in the environment are louder than, and of
a similar frequency as, auditory signals an animal is trying to
receive. Masking is a phenomenon that affects animals that
[[Page 21527]]
are trying to receive acoustic information about their environment,
including sounds from other members of their species, predators, prey,
and sounds that allow them to orient in their environment. Masking
these acoustic signals can disturb the behavior of individual animals,
groups of animals, or entire populations.
Masking occurs when anthropogenic sounds and signals (that the
animal utilizes) overlap at both spectral and temporal scales. For the
airgun sound generated from the proposed seismic survey, sound will
consist of low frequency (under 500 Hz) pulses with extremely short
durations (less than one second). Lower frequency man-made sounds are
more likely to affect detection of communication calls and other
potentially important natural sounds such as surf and prey noise. There
is little concern regarding masking near the sound source due to the
brief duration of these pulses and relatively longer silence between
airgun shots (approximately 3-4 seconds). However, at long distances
(over tens of kilometers away), due to multipath propagation and
reverberation, the durations of airgun pulses can be ``stretched'' to
seconds with long decays (Madsen et al., 2006), although the intensity
of the sound is greatly reduced.
This 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., 2009) and cause
increased stress levels (e.g., Foote et al., 2004; Holt et al., 2009).
Marine mammals are thought to be able to compensate for masking by
adjusting their acoustic behavior by shifting call frequencies, and/or
increasing call volume and vocalization rates. For example, blue whales
are found to increase call rates when exposed to seismic survey noise
in the St. Lawrence Estuary (Di Iorio and Clark, 2010). The North
Atlantic right whales exposed to high shipping noise increase call
frequency (Parks et al., 2007), while some humpback whales respond to
low-frequency active sonar playbacks by increasing song length (Miller
el al., 2000). Bowhead whale calls are frequently detected in the
presence of seismic pulses, although the number of calls detected may
sometimes be reduced (Richardson et al., 1986; Greene et al., 1999),
possibly because animals moved away from the sound source or ceased
calling (Blackwell et al., 2013). Additionally, beluga whales have been
known to change their vocalizations in the presence of high background
noise possibly to avoid masking calls (Au et al., 1985; Lesage et al.,
1999; Scheifele et al., 2005). 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., 1995). 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 sounds by improving
the effective signal-to-noise ratio. In the cases of higher 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 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., 1995). This ability may be useful in
reducing masking at these frequencies. In summary, high levels of sound
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.
3. Behavioral Disturbance
Marine mammals may behaviorally react when exposed to anthropogenic
sound. These behavioral reactions are often shown as: changing
durations of surfacing and dives, number of blows per surfacing, or
moving direction and/or speed; reduced/increased vocal activities;
changing/cessation of certain behavioral activities (such as
socializing or feeding); visible startle response or aggressive
behavior (such as tail/fluke slapping or jaw clapping); avoidance of
areas where sound sources are located; and/or flight responses (e.g.,
pinnipeds flushing into water from haulouts or rookeries).
The biological significance of many of these behavioral
disturbances is difficult to predict, especially if the detected
disturbances appear minor. However, the consequences of behavioral
modification have the potential to be biologically significant if the
change affects growth, survival, or reproduction. Examples of
significant behavioral modifications include:
Drastic change in diving/surfacing patterns (such as those
thought to be causing beaked whale stranding due to
[[Page 21528]]
exposure to military mid-frequency tactical sonar);
Habitat abandonment due to loss of desirable acoustic
environment; and
Cessation of feeding or social interaction.
The onset of behavioral disturbance from anthropogenic noise
depends on both external factors (characteristics of noise sources and
their paths) and the receiving animals (hearing, motivation,
experience, demography, current activity, reproductive state) and is
also difficult to predict (Gordon et al., 2004; Southall et al., 2007;
Ellison et al., 2011).
Mysticetes: 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 BP's proposed survey (total discharge volume
of 30 in\3\), the distance to received levels in the 160 dB re 1 [mu]Pa
rms range is estimated to be 1 mi (1.6 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 begin to show avoidance reactions at a received level of
about 160-170 dB re 1 [mu]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. In any event, the proposed survey will
occur in summer (July through late August) when most bowhead whales are
commonly feeding in the Mackenzie River Delta, Canada.
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. (1995) 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., 1995 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., 1995 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
[[Page 21529]]
Richardson et al., 1995 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., 1995) observed that migrating gray whales
rarely exhibited noticeable reactions to a straight-line overflight by
a Twin Otter at 197 ft (60 m) altitude.
Odontocetes: Few systematic data are available describing reactions
of toothed whales to noise pulses. 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). Miller et al. (2009) conducted at-sea
experiments where reactions of sperm whales were monitored through the
use of controlled sound exposure experiments from large airgun arrays
consisting of 20-guns and 31-guns. Of 8 sperm whales observed, none
changed their behavior when exposed to either a ramp-up at 4-8 mi (7-13
km) or full array exposures at 0.6-8 mi (1-13 km).
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 in certain geographic areas) 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 10-20 km (6.2-12.4 mi) 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 have been avoiding the seismic operations at
distances of 10-20 km (6.2-12.4 mi) (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 (pk-pk level >200 dB re 1 [mu]Pa) before
exhibiting aversive behaviors.
Observers stationed on seismic vessels operating off the United
Kingdom from 1997-2000 have provided data on the occurrence and
behavior of various toothed whales exposed to seismic pulses (Stone,
2003; Gordon et al., 2004). Killer whales were found to be
significantly farther from large airgun arrays during periods of
shooting compared with periods of no shooting. The displacement of the
median distance from the array was approximately 0.5 km (0.3 mi) or
more. Killer whales also appear to be more tolerant of seismic shooting
in deeper water.
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.
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.
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. Monitoring work
in the Alaskan Beaufort Sea during 1996-2001 provided considerable
information regarding the behavior of Arctic ice 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 100 m (328 ft) to a few hundreds of meters, and
many seals remained within 100-200 m (328-656 ft) 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., 1995).
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.
Blackwell et al. (2004) 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.
(2004) 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., 1995; Born et al., 1999).
4. Threshold Shift (Noise-Induced Loss of Hearing)
When animals exhibit reduced hearing sensitivity (i.e., sounds must
be louder for an animal to detect them) following exposure to an
intense sound or sound for long duration, it is referred to as a noise-
induced threshold shift (TS). An animal can experience temporary
threshold shift (TTS) or permanent threshold shift (PTS). TTS can last
from minutes or hours to days (i.e., there is complete recovery), can
occur in specific frequency ranges (i.e., an animal might only have a
temporary loss of hearing sensitivity between the frequencies of 1 and
10 kHz), and can
[[Page 21530]]
be of varying amounts (for example, an animal's hearing sensitivity
might be reduced initially by only 6 dB or reduced by 30 dB). PTS is
permanent, but some recovery is possible. PTS can also occur in a
specific frequency range and amount as mentioned above for TTS.
The following physiological mechanisms are thought to play a role
in inducing auditory TS: Effects to sensory hair cells in the inner ear
that reduce their sensitivity, modification of the chemical environment
within the sensory cells, residual muscular activity in the middle ear,
displacement of certain inner ear membranes, increased blood flow, and
post-stimulatory reduction in both efferent and sensory neural output
(Southall et al., 2007). The amplitude, duration, frequency, temporal
pattern, and energy distribution of sound exposure all can affect the
amount of associated TS and the frequency range in which it occurs. As
amplitude and duration of sound exposure increase, so, generally, does
the amount of TS, along with the recovery time. For intermittent
sounds, less TS could occur than compared to a continuous exposure with
the same energy (some recovery could occur between intermittent
exposures depending on the duty cycle between sounds) (Kryter et al.,
1966; Ward, 1997). For example, one short but loud (higher SPL) sound
exposure may induce the same impairment as one longer but softer sound,
which in turn may cause more impairment than a series of several
intermittent softer sounds with the same total energy (Ward, 1997).
Additionally, though TTS is temporary, prolonged exposure to sounds
strong enough to elicit TTS, or shorter-term exposure to sound levels
well above the TTS threshold, can cause PTS, at least in terrestrial
mammals (Kryter, 1985). Although in the case of the proposed shallow
geohazard survey, animals are not expected to be exposed to sound
levels for durations long enough to result in PTS.
PTS is considered auditory injury (Southall et al., 2007).
Irreparable damage to the inner or outer cochlear hair cells may cause
PTS; however, other mechanisms are also involved, such as exceeding the
elastic limits of certain tissues and membranes in the middle and inner
ears and resultant changes in the chemical composition of the inner ear
fluids (Southall et al., 2007).
Although the published body of scientific literature contains
numerous theoretical studies and discussion papers on hearing
impairments that can occur with exposure to a loud sound, only a few
studies provide empirical information on the levels at which noise-
induced loss in hearing sensitivity occurs in nonhuman animals. For
marine mammals, published data are limited to the captive bottlenose
dolphin, beluga, harbor porpoise, and Yangtze finless porpoise
(Finneran et al., 2000, 2002b, 2003, 2005a, 2007, 2010a, 2010b;
Finneran and Schlundt, 2010; Lucke et al., 2009; Mooney et al., 2009a,
2009b; Popov et al., 2011a, 2011b; Kastelein et al., 2012a; Schlundt et
al., 2000; Nachtigall et al., 2003, 2004). For pinnipeds in water, data
are limited to measurements of TTS in harbor seals, an elephant seal,
and California sea lions (Kastak et al., 1999, 2005; Kastelein et al.,
2012b).
Marine mammal hearing plays a critical role in communication with
conspecifics, and 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
(similar to those discussed in auditory masking, below). 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 occurs
during a time 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 time when communication is critical
for successful mother/calf interactions could have more serious
impacts. Also, depending on the degree and frequency range, the effects
of PTS on an animal could range in severity, although it is considered
generally more serious because it is a permanent condition. Of note,
reduced hearing sensitivity as a simple function of aging has been
observed in marine mammals, as well as humans and other taxa (Southall
et al., 2007), so we can infer that strategies exist for coping with
this condition to some degree, though likely not without cost.
Marine mammals are unlikely to be exposed to received levels of
seismic pulses strong enough to cause more than slight TTS, and, given
the higher level of sound necessary to cause PTS, it is even less
likely that PTS could occur as a result of the proposed shallow
geohazard survey.
5. Non-Auditory Physical Effects
Non-auditory physical effects might 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.
Some marine mammal species (i.e., beaked whales) may be especially
susceptible to injury and/or stranding when exposed to strong pulsed
sounds.
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 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,
[[Page 21531]]
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, we assume that reducing a marine mammal's ability to gather
information about its environment and communicate with other members of
its species would induce stress, based on data that terrestrial animals
exhibit those responses under similar conditions (NRC, 2003) and
because marine mammals 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. 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.
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 project 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. There is no definitive evidence that any of
these effects occur even for marine mammals in close proximity to large
arrays of airguns, which are not proposed for use during this program.
In addition, marine mammals that show behavioral avoidance of industry
activities, including bowheads, belugas, and some pinnipeds, are
especially unlikely to incur non-auditory impairment or other physical
effects.
6. Stranding and Mortality
Marine mammals close to underwater detonations of high explosive
can be killed or severely injured, and the auditory organs are
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995).
Airgun pulses are less energetic and their peak amplitudes have slower
rise times. To date, there is no evidence that serious injury, death,
or stranding by marine mammals can occur from exposure to airgun
pulses, even in the case of large airgun arrays. Additionally, BP's
project will use a very small airgun array in shallow water. NMFS does
not expect any marine mammals will incur serious injury or mortality in
the shallow waters of Foggy Island Bay or strand as a result of the
proposed shallow geohazard survey.
7. Potential Effects From Sonar Systems on Marine Mammals
The multibeam echosounder proposed for use during BP's survey does
not produce frequencies within the hearing range of marine mammals.
Exposure to sounds generated by this instrument, therefore, does not
present a risk of potential physiological damage, hearing impairment,
and/or behavioral responses.
The sidescan sonar does not produce frequencies within the hearing
range of
[[Page 21532]]
mysticetes and ice seals, but when operating at 110-135 kHz could be
audible by mid- and high-frequency cetaceans, depending on the strength
of the signal. However, when it operates at the much higher frequencies
greater than 400 kHz, it is outside of the hearing range of all marine
mammals. The signal from side scan sonars is narrow, typically in the
form of a conical beam projected directly below the vessel. Based on
previous measurements of a sidescan sonar working at similar
frequencies in deeper water, distances to sound levels of 190 and 180
dB re 1 [mu]Pa (rms) were 22 and 47 m, respectively (Warner and
McCrodan, 2011). It is unlikely that an animal would be exposed for an
extended time to a signal strong enough for TTS or PTS to occur, unless
the animal is present within the beam under the vessel and swimming
with the same speed and direction. The distance at which beluga whales
could react behaviorally to the sidescan sonar signal is about 200 m
(Warner and McCrodan, 2011). However, the response, if it occurs at
all, is expected to be short term. Masking is unlikely to occur due to
the nature of the signal and because beluga whales and ice seals
generally vocalize at frequencies lower than 100 kHz.
Subbottom profilers will be audible to all three hearing classes of
marine mammals that occur in the project area. Based on previous
measurements of various subbottom profilers, the rms sound pressure
level does not reach 180 dB re 1 [mu]Pa (Funk et al., 2008; Ireland et
al., 2009; Warner and McCrodan, 2011). Distances to sound levels that
could result in mild behavioral responses, such as avoidance, ranged
from 1 to 30 m. Masking is unlikely due to the low duty cycle,
directionality, and brief period when an individual mammal is likely to
be within the beam. Additionally, the higher frequencies of the
instrument are unlikely to overlap with the lower frequency calls by
mysticetes.
Some stranding events of mid-frequency cetaceans were attributed to
the presence of sonar surveys in the area (e.g., Southall et al.,
2006). Recently, an independent scientific review panel concluded that
the mass stranding of approximately 100 melon-headed whales in
northwest Madagascar in 2008 was primarily triggered by a multibeam
echosounder system (Southall et al., 2013), acknowledging that it was
difficult to find evidence showing a direct cause-effect relationships.
The multibeam echosounder proposed in this survey will operate at much
higher frequencies, outside the hearing range of any marine mammal. The
sidescan sonar and subbottom profiler are much less powerful.
Considering the acoustic specifics of these instruments, the shallow
water environment, the unlikely presence of toothed whales in the area,
and planned mitigation measures, no marine mammal stranding or
mortality are expected.
Vessel Impacts
Vessel activity and noise associated with vessel activity will
temporarily increase in the action area during BP's survey as a result
of the operation of one vessel. To minimize the effects of the vessel
and noise associated with vessel activity, BP will alter speed if a
marine mammal gets too close to a vessel. In addition, the vessel will
be operating at slow speed (3-4 knots) when conducting surveys. Marine
mammal monitoring observers will alert the vessel captain as animals
are detected to ensure safe and effective measures are applied to avoid
coming into direct contact with marine mammals. Therefore, NMFS neither
anticipates nor authorizes takes of marine mammals from ship strikes.
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.
Odontocetes, such as beluga whales, killer whales, and harbor
porpoises, often show tolerance to vessel activity; however, they may
react at long distances if they are confined by ice, shallow water, or
were previously harassed by vessels (Richardson et al., 1995). Beluga
whale response to vessel noise varies greatly from tolerance to extreme
sensitivity depending on the activity of the whale and previous
experience with vessels (Richardson et al., 1995). Reactions to vessels
depends on whale activities and experience, habitat, boat type, and
boat behavior (Richardson et al., 1995) and may include behavioral
responses, such as altered headings or avoidance (Blane and Jaakson,
1994; Erbe and Farmer, 2000); fast swimming; changes in vocalizations
(Lesage et al., 1999; Scheifele et al., 2005); and changes in dive,
surfacing, and respiration patterns.
There are few data published on pinniped responses to vessel
activity, and most of the information is anecdotal (Richardson et al.,
1995). Generally, sea lions in water show tolerance to close and
frequently approaching vessels and sometimes show interest in fishing
vessels. They are less tolerant when hauled out on land; however, they
rarely react unless the vessel approaches within 100-200 m (330-660 ft;
reviewed in Richardson et al., 1995).
The addition of one vessel and noise due to vessel operations
associated with the survey is not expected to have effects that could
cause significant or long-term consequences for individual marine
mammals or their populations.
Anticipated Effects on Marine Mammal Habitat
The primary potential impacts to marine mammal habitat and other
marine species are associated with elevated sound levels produced by
airguns and other active acoustic sources. 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 Project 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). When feeding in
relatively shallow areas, bowheads feed throughout the
[[Page 21533]]
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 (which is
approximately 90 mi east of BP's proposed survey area) 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).
Recent articles and reports have noted bowhead whales feeding in
several areas of the U.S. Beaufort Sea. The Barrow area is commonly
used as a feeding area during spring and fall, with a higher proportion
of photographed individuals displaying evidence of feeding in fall
rather than spring (Mocklin, 2009). A bowhead whale feeding ``hotspot''
(Okkonen et al., 2011) commonly forms on the western Beaufort Sea shelf
off Point Barrow in late summer and fall. Favorable conditions
concentrate euphausiids and copepods, and bowhead whales congregate to
exploit the dense prey (Ashjian et al., 2010, Moore et al., 2010;
Okkonen et al., 2011). Surveys have also noted bowhead whales feeding
in the Camden Bay area during the fall (Koski and Miller, 2009;
Quakenbush et al., 2010).
The 2006-2008 BWASP Final Report (Clarke et al., 2011a) and the
2009 BWASP Final Report (Clarke et al., 2011b) note sightings of
feeding bowhead whales in the Beaufort Sea during the fall season.
During that 4 year period, the largest groups of feeding whales were
sighted between Smith Bay and Point Barrow (hundreds of miles to the
west of Prudhoe Bay), and none were sighted feeding in Camden Bay
(Clarke et al., 2011a,b). Clarke and Ferguson (undated) examined the
raw BWASP data from the years 2000-2009. They noted that feeding
behavior was noted more often in September than October and that while
bowheads were observed feeding throughout the study area (which
includes the entire U.S. Beaufort Sea), sightings were less frequent in
the central Alaskan Beaufort than they were east of Kaktovik and west
of Smith Bay. Additionally, Clarke and Ferguson (undated) and Clarke et
al. (2011b) refer to information from Ashjian et al. (2010), which
describes the importance of wind-driven currents that produce favorable
feeding conditions for bowhead whales in the area between Smith Bay and
Point Barrow. Increased winds in that area may be increasing the
incidence of upwelling, which in turn may be the reason for increased
sightings of feeding bowheads in the area. Clarke and Ferguson
(undated) also note that the incidence of feeding bowheads in the
eastern Alaskan Beaufort Sea has decreased since the early 1980s.
Beluga whales feed on a variety of fish, shrimp, squid and octopus
(Burns and Seaman, 1985). Very few beluga whales occur nearshore; their
main migration route is much further offshore. Like several of the
other species in the area, harbor porpoise feed on demersal and benthic
species, mainly schooling fish and cephalopods. Depending on the type
of killer whale (transient or resident), they feed on fish and/or
marine mammals. However, harbor porpoises and killer whales are not
commonly found in Foggy Island Bay.
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). However, the central Beaufort Sea is not known to be a
primary feeding ground for gray whales.
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 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). Epifauna, which
live attached to hard substrates, are rare in the Beaufort Sea because
hard substrates are scarce there. A small community of epifauna, the
Boulder Patch, occurs in Stefansson Sound.
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).
Nearshore benthic fauna have been studied in Beaufort Sea lagoons
and near the mouth of the Colville River (Kinney et al., 1971, 1972;
Crane and Cooney, 1975). The waters of Simpson Lagoon, Harrison Bay,
and the nearshore region support a number of infaunal species including
crustaceans, mollusks, and polychaetes. In areas influenced by river
discharge, seasonal changes in salinity can greatly influence the
distribution and abundance of benthic organisms. Large fluctuations in
salinity and temperature that occur over a very short time period, or
on a seasonal basis, allow only very adaptable, opportunistic species
to survive (Alexander et al., 1974). Since shorefast ice is present for
many months, the distribution and abundance of most species depends on
[[Page 21534]]
annual (or more frequent) recolonization from deeper offshore waters
(Woodward Clyde Consultants, 1995). Due to ice scouring, particularly
in water depths of less than 8 ft (2.4 m), infaunal communities tend to
be patchily distributed. Diversity increases with water depth until the
shear zone is reached at 49-82 ft (15-25 m; Carey, 1978). Biodiversity
then declines due to ice gouging between the landfast ice and the polar
pack ice (Woodward Clyde Consultants, 1995).
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
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 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 BP's proposed survey.
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).
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). In calm
weather, ambient noise levels in audible parts of the spectrum lie
between 60 dB to 100 dB.
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 [mu]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 [mu]Pa. They noted:
Startle responses at received levels of 200-205 dB re 1
[mu]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 [mu]Pa may cause subtle changes in behavior. Pulses at
levels of 180 dB
[[Page 21535]]
may cause noticeable changes in behavior (Chapman and Hawkins, 1969;
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.
Some of the fish species found in the Arctic are prey sources for
odontocetes and pinnipeds. A reaction by fish to sounds produced by
BP's proposed survey 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.
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, of reduced prey abundance.
Some mysticetes, including bowhead whales, feed on concentrations
of zooplankton. Some feeding bowhead whales may occur in the Alaskan
Beaufort Sea in July and August, but feeding bowheads are more likely
to occur in the area after the cessation of BP's survey operations.
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. Behavior of zooplankters is not
expected to be affected by the survey. These animals have exoskeletons
and no air bladders. Many crustaceans can make sounds, and some
crustacea and other invertebrates have some type of sound receptor. A
reaction by zooplankton to sounds produced by the seismic survey 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. Impacts on zooplankton behavior are
predicted to be inconsequential. Thus, feeding mysticetes would not be
adversely affected by this minimal loss or scattering, if any, of
reduced zooplankton abundance.
Based on the preceding discussion, the proposed activity is not
expected to have any habitat-related effects that could cause
significant or long-term consequences for individual marine mammals or
their populations.
Proposed Mitigation
In order to issue an incidental take authorization (ITA) under
section 101(a)(5)(D) of the MMPA, NMFS must 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).
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).
Mitigation Measures Proposed by BP
For the proposed mitigation measures, BP proposed general
mitigation measures that apply throughout the survey and specific
mitigation measures that apply to airgun operations. The proposed
protocols are discussed next and can also be found in Section 11 of
BP's application (see ADDRESSES).
1. General Mitigation Measures
These general mitigation measures are proposed to apply at all
times to the vessel involved in the Liberty geohazard survey. This
vessel would also operate under an additional set of specific
mitigation measures during airgun operations (described a bit later in
this document).
The general mitigation measures include: (1) Adjusting speed to
avoid collisions with whales and during periods of low visibility; (2)
checking the waters immediately adjacent to the vessel to ensure that
no marine mammals will be injured when the vessel's propellers (or
screws) are engaged; (3) avoiding concentrations of groups of whales
and not operating vessels in a way that separates members of a group;
(4) reducing vessel speeds to less than 10 knots in the presence of
feeding whales; (5) reducing speed and steering around groups of whales
if circumstances allow (but never cutting off a whale's travel path)
and avoiding multiple changes in direction and speed when within 900 ft
of whales; (6) maintaining an altitude of at least 1,000 ft when flying
helicopters, except in emergency situations or during take-offs and
landings; and (7) not hovering or circling with helicopters above or
within 0.3 mi of groups of whales.
2. Seismic Airgun Mitigation Measures
BP proposes to establish and monitor Level A harassment exclusion
zones for all marine mammal species. These zones will be monitored by
Protected Species Observers (PSOs; more detail later). Should marine
mammals enter these exclusion zones, the PSOs will call for and
implement the Suite of mitigation measures described next.
Ramp-up Procedure: Ramp-up procedures of an airgun array involve a
step-wise increase in the number of operating airguns until the
required discharge volume is achieved. The purpose of a ramp-up
(sometimes referred to as ``soft-start'') is to provide marine mammals
in the vicinity of the activity the opportunity to leave the area and
to avoid the potential for injury or impairment of their hearing
abilities.
During ramp-up, BP proposes to implement the common procedure of
doubling the number of operating airguns at 5-minute intervals,
starting with the smallest gun in the array. Ramp-up of the 30 in\3\
array from a shutdown will therefore take 10 min for the three-airgun
array option and 5 min for the two-airgun array option. First the
smallest gun in the array will be activated (10 in\3\) and after 5 min,
the second airgun (10 in\3\ or 20 in\3\). For the three-airgun array,
an additional 5 min are then required to activate the third 10 in\3\
airgun. During ramp-up, the exclusion zone for the full airgun array
will be observed. The ramp-up procedures will be applied as follows:
1. A ramp-up, following a cold start, can be applied if the
exclusion zone has been free of marine mammals for a consecutive 30-
minute period. The entire exclusion zone must have been visible during
these 30 minutes. If the entire exclusion zone is not visible, then
ramp-up from a cold start cannot begin.
2. Ramp-up procedures from a cold start will be delayed if a marine
mammal is sighted within the exclusion zone during the 30-minute period
prior to the ramp-up. The delay will last until the marine mammal(s)
has been observed to leave the exclusion zone or until the animal(s) is
not sighted for at least 15 minutes (seals) or 30 minutes (cetaceans).
3. A ramp-up, following a shutdown, can be applied if the marine
mammal(s) for which the shutdown occurred has been observed to leave
the exclusion zone or until the animal(s) has not been sighted for at
least 15 minutes (seals) or 30 minutes (cetaceans). This assumes there
was a continuous observation effort prior to the shutdown and the
entire exclusion zone is visible.
4. If, for any reason, power to the airgun array has been
discontinued for a period of 10 minutes or more, ramp-up procedures
need to be implemented. Only if the PSO watch has been suspended, a 30-
minute clearance of the
[[Page 21536]]
exclusion zone is required prior to commencing ramp-up. Discontinuation
of airgun activity for less than 10 minutes does not require a ramp-up.
5. The seismic operator and PSOs will maintain records of the times
when ramp-ups start and when the airgun arrays reach full power.
Power Down Procedure: A power down is the immediate reduction in
the number of operating airguns such that the radii of the 190 dB and
180 dB (rms) zones are decreased to the extent that an observed marine
mammal is not in the applicable exclusion zone of the full array. For
this geohazard survey, the operation of one airgun continues during a
power down. The continued operation of one airgun is intended to (a)
alert marine mammals to the presence of airgun activity, and (b) retain
the option of initiating a ramp up to full operations under poor
visibility conditions.
1. The array will be immediately powered down whenever a marine
mammal is sighted approaching close to or within the applicable
exclusion zone of the full array, but is outside the applicable
exclusion zone of the single airgun;
2. Likewise, if a mammal is already within the exclusion zone of
the full array when first detected, the airgun array will be powered
down to one operating gun immediately;
3. If a marine mammal is sighted within or about to enter the
applicable exclusion zone of the single airgun, it too will be shut
down; and
4. Following a power down, ramp-up to the full airgun array will
not resume until the marine mammal has cleared the applicable exclusion
zone. The animal will be considered to have cleared the exclusion zone
if it has been visually observed leaving the exclusion zone of the full
array, or has not been seen within the zone for 15 minutes (seals) or
30 minutes (cetaceans).
Shut-down Procedures: The operating airgun(s) will be shut down
completely if a marine mammal approaches or enters the 190 or 180 dB
(rms) exclusion radius of the smallest airgun. Airgun activity will not
resume until the marine mammal has cleared the applicable exclusion
radius of the full array. The animal will be considered to have cleared
the exclusion radius as described above under ramp-up procedures.
Poor Visibility Conditions: BP plans to conduct 24-hr operations.
PSOs will not be on duty during ongoing seismic operations during
darkness, given the very limited effectiveness of visual observation at
night (there will be no periods of darkness in the survey area until
mid-August). The proposed provisions associated with operations at
night or in periods of poor visibility include the following:
If during foggy conditions, heavy snow or rain, or
darkness (which may be encountered starting in late August), the full
180 dB exclusion zone is not visible, the airguns cannot commence a
ramp-up procedure from a full shut-down; and
If one or more airguns have been operational before
nightfall or before the onset of poor visibility conditions, they can
remain operational throughout the night or poor visibility conditions.
In this case ramp-up procedures can be initiated, even though the
exclusion zone may not be visible, on the assumption that marine
mammals will be alerted by the sounds from the single airgun and have
moved away.
BP is aware that available techniques to effectively detect marine
mammals during limited visibility conditions (darkness, fog, snow, and
rain) are in need of development and has in recent years supported
research and field trials intended to improve methods of detecting
marine mammals under these conditions.
Additional Mitigation Measures Proposed by NMFS
The mitigation airgun will be operated at approximately one shot
per minute and will not be operated for longer than three hours in
duration during daylight hours and good visibility. In cases when the
next start-up after the turn is expected to be during lowlight or low
visibility, use of the mitigation airgun may be initiated 30 minutes
before darkness or low visibility conditions occur and may be operated
until the start of the next seismic acquisition line. The mitigation
gun must still be operated at approximately one shot per minute.
Mitigation Conclusions
NMFS has carefully evaluated BP'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 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 measures are 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.
Any mitigation measure(s) prescribed by NMFS should be able to
accomplish, have a reasonable likelihood of accomplishing (based on
current science), or contribute to the accomplishment of one or more of
the general goals listed below:
1. Avoidance or minimization of injury or death of marine mammals
wherever possible (goals 2, 3, and 4 may contribute to this goal).
2. A reduction in the numbers of marine mammals (total number or
number at biologically important time or location) exposed to received
levels of seismic airguns, or other activities expected to result in
the take of marine mammals (this goal may contribute to 1, above, or to
reducing harassment takes only).
3. A reduction in the number of times (total number or number at
biologically important time or location) individuals would be exposed
to received levels of seismic airguns or other activities expected to
result in the take of marine mammals (this goal may contribute to 1,
above, or to reducing harassment takes only).
4. A reduction in the intensity of exposures (either total number
or number at biologically important time or location) to received
levels of seismic airguns or other activities expected to result in the
take of marine mammals (this goal may contribute to 1, above, or to
reducing the severity of harassment takes only).
5. Avoidance or minimization of adverse effects to marine mammal
habitat, paying special attention to the food base, activities that
block or limit passage to or from biologically important areas,
permanent destruction of habitat, or temporary destruction/disturbance
of habitat during a biologically important time.
6. For monitoring directly related to mitigation--an increase in
the probability of detecting marine mammals, thus allowing for more
effective implementation of the mitigation.
Based on our evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS, NMFS has preliminarily
determined that the proposed mitigation measures provide the means of
effecting the least practicable impact on marine mammals species or
stocks and their habitat, paying particular attention to rookeries,
mating grounds, and areas of similar significance. Proposed measures to
[[Page 21537]]
ensure availability of such species or stock for taking for certain
subsistence uses are 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 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. BP
submitted information regarding marine mammal monitoring to be
conducted during seismic operations as part of the IHA application.
That information can be found in Sections 11 and 13 of the application.
The monitoring measures may be modified or supplemented based on
comments or new information received from the public during the public
comment period.
Monitoring measures proposed by the applicant or prescribed by NMFS
should accomplish one or more of the following top-level goals:
1. An increase in our understanding of the likely occurrence of
marine mammal species in the vicinity of the action, i.e., presence,
abundance, distribution, and/or density of species.
2. An increase in our understanding of the nature, scope, or
context of the likely exposure of marine mammal species to any of the
potential stressor(s) associated with the action (e.g. sound or visual
stimuli), through better understanding of one or more of the following:
the action itself and its environment (e.g. sound source
characterization, propagation, and ambient noise levels); the affected
species (e.g. life history or dive pattern); the likely co-occurrence
of marine mammal species with the action (in whole or part) associated
with specific adverse effects; and/or the likely biological or
behavioral context of exposure to the stressor for the marine mammal
(e.g. age class of exposed animals or known pupping, calving or feeding
areas).
3. An increase in our understanding of how individual marine
mammals respond (behaviorally or physiologically) to the specific
stressors associated with the action (in specific contexts, where
possible, e.g., at what distance or received level).
4. An increase in our understanding of how anticipated individual
responses, to individual stressors or anticipated combinations of
stressors, may impact either: the long-term fitness and survival of an
individual; or the population, species, or stock (e.g. through effects
on annual rates of recruitment or survival).
5. An increase in our understanding of how the activity affects
marine mammal habitat, such as through effects on prey sources or
acoustic habitat (e.g., through characterization of longer-term
contributions of multiple sound sources to rising ambient noise levels
and assessment of the potential chronic effects on marine mammals).
6. An increase in understanding of the impacts of the activity on
marine mammals in combination with the impacts of other anthropogenic
activities or natural factors occurring in the region.
7. An increase in our understanding of the effectiveness of
mitigation and monitoring measures.
8. An increase in the probability of detecting marine mammals
(through improved technology or methodology), both specifically within
the safety zone (thus allowing for more effective implementation of the
mitigation) and in general, to better achieve the above goals.
Proposed Monitoring Measures
1. Visual Monitoring
Two observers referred to as PSOs will be present on the vessel. Of
these two PSOs, one will be on watch at all times to monitor the 190
and 180 dB exclusion zones for the presence of marine mammals during
airgun operations. The main objectives of the vessel-based marine
mammal monitoring are as follows: (1) To implement mitigation measures
during seismic operations (e.g. course alteration, airgun power down,
shut-down and ramp-up); and (2) To record all marine mammal data needed
to estimate the number of marine mammals potentially affected, which
must be reported to NMFS within 90 days after the survey.
BP intends to work with experienced PSOs. At least one Alaska
Native resident, who is knowledgeable about Arctic marine mammals and
the subsistence hunt, is expected to be included as one of the team
members aboard the vessel. Before the start of the survey, the vessel
crew will be briefed on the function of the PSOs, their monitoring
protocol, and mitigation measures to be implemented.
At least one observer will monitor for marine mammals at any time
during daylight hours (there will be no periods of total darkness until
mid-August). PSOs will be on duty in shifts of a maximum of 4 hours at
a time, although the exact shift schedule will be established by the
lead PSO in consultation with the other PSOs.
The vessel will offer a suitable platform for marine mammal
observations. Observations will be made from locations where PSOs have
the best view around the vessel. During daytime, the PSO(s) will scan
the area around the vessel systematically with reticle binoculars and
with the naked eye. Because the main purpose of the PSO on board the
vessel is detecting marine mammals for the implementation of mitigation
measures according to specific guidelines, BP prefers to keep the
information to be recorded as concise as possible, allowing the PSO to
focus on detecting marine mammals. The following information will be
collected by the PSOs:
Environmental conditions--consisting of sea state (in
Beaufort Wind force scale according to NOAA), visibility (in km, with
10 km indicating the horizon on a clear day), and sun glare (position
and severity). These will be recorded at the start of each shift,
whenever there is an obvious change in one or more of the environmental
variables, and whenever the observer changes shifts;
Project activity--consisting of airgun operations (on or
off), number of active guns, line number. This will be recorded at the
start of each shift, whenever there is an obvious change in project
activity, and whenever the observer changes shifts; and
Sighting information--consisting of the species (if
determinable), group size, position and heading relative to the vessel,
behavior, movement, and distance relative to the vessel (initial and
closest approach). These will be recorded upon sighting a marine mammal
or group of animals.
When marine mammals in the water are detected within or about to
enter the designated exclusion zones, the airgun(s) power down or shut-
down procedures will be implemented immediately. To assure prompt
implementation of power downs and shut-downs, multiple channels of
communication between the PSOs and the airgun technicians will be
established. During the power down and shut-down, the PSO(s) will
continue to maintain watch to determine when the
[[Page 21538]]
animal(s) are outside the exclusion radius. Airgun operations can be
resumed with a ramp-up procedure (depending on the extent of the power
down) if the observers have visually confirmed that the animal(s) moved
outside the exclusion zone, or if the animal(s) were not observed
within the exclusion zone for 15 minutes (seals) or for 30 minutes
(cetaceans). Direct communication with the airgun operator will be
maintained throughout these procedures.
All marine mammal observations and any airgun power down, shut-
down, and ramp-up will be recorded in a standardized format. Data will
be entered into or transferred to a custom database. The accuracy of
the data entry will be verified daily through QA/QC procedures.
Recording procedures will allow initial summaries of data to be
prepared during and shortly after the field program, and will
facilitate transfer of the data to other programs for further
processing and archiving.
2. Fish and Airgun Sound Monitoring
BP proposes to conduct research on fish species in relation to
airgun operations, including prey species important to ice seals,
during the proposed seismic survey. The Liberty shallow geohazard
survey, along with another seismic survey BP is conducting this summer
in Prudhoe Bay, offers a unique opportunity to assess the impacts of
airgun sounds on fish, specifically on changes in fish abundance in
fyke nets that have been sampled in the area for more than 30 years.
The monitoring study would occur over a 2-month period during the open-
water season. During this time, fish are counted and sized every day,
unless sampling is prevented by weather, the presence of bears, or
other events. Fish mortality is also noted.
The fish-sampling period coincides with the shallow geohazard
survey, resulting in a situation where each of the four fyke nets will
be exposed to varying daily exposures to airgun sounds. That is, as
source vessels move back and forth across the project area, fish caught
in nets will be exposed to different sounds levels at different nets
each day. To document relationships between fish catch in each fyke net
and received sound levels, BP will attempt to instrument each fyke net
location with a recording hydrophone. Recording hydrophones, to the
extent possible, will have a dynamic range that extends low enough to
record near ambient sounds and high enough to capture sound levels
during relatively close approaches by the airgun array (i.e., likely
levels as high as about 200 dB re 1 uPa). Bandwidth will extend from
about 10 Hz to at least 500 Hz. In addition, because some fish
(especially salmonids) are likely to be sensitive to particle velocity
instead of or in addition to sound pressure level, BP will attempt to
instrument each fyke net location with a recording particle velocity
meter. Acoustic and environmental data will be used in statistical
models to assess relationships between acoustic and fish variables.
Additional information on the details of the fish monitoring study can
be found in Section 13.1 of BP'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)).
Because of the extremely short duration of BP's proposed survey,
the fact that activities will be completed prior to any fall bowhead
whale subsistence hunts, and that seal hunts occur more than 50 mi from
the proposed survey activities, NMFS determined that the proposed
survey did not meet the trigger for requiring an independent peer
review of the monitoring plan.
Reporting Measures
1. 90-Day Technical Report
A report will be submitted to NMFS within 90 days after the end of
the proposed shallow geohazard survey. The report will summarize all
activities and monitoring results conducted during in-water seismic
surveys. The Technical Report will include the following:
Summary of project start and end dates, airgun activity,
number of guns, and the number and circumstances of implementing ramp-
up, power down, shutdown, and other mitigation actions;
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);
Analyses of the effects of various factors influencing
detectability of marine mammals (e.g., sea state, number of observers,
and fog/glare);
Species composition, occurrence, and distribution of
marine mammal sightings, including date, water depth, numbers, age/
size/gender categories (if determinable), and group sizes;
Analyses of the effects of survey operations;
Sighting rates of marine mammals during periods with and
without seismic survey activities (and other variables that could
affect detectability), such as: (i) Initial sighting distances versus
survey activity state; (ii) closest point of approach versus survey
activity state; (iii) observed behaviors and types of movements versus
survey activity state; (iv) numbers of sightings/individuals seen
versus survey activity state; (v) distribution around the source
vessels versus survey activity state; and (vi) estimates of exposures
of marine mammals to Level B harassment thresholds based on presence in
the 160 dB harassment zone.
2. Fish and Airgun Sound Report
BP proposes to present the results of the fish and airgun sound
study to NMFS in a detailed report that will also be submitted to a
peer reviewed journal for publication, presented at a scientific
conference, and presented in Barrow and Nuiqsut.
3. Notification of Injured or Dead Marine Mammals
In the unanticipated event that the specified activity clearly
causes the take of a marine mammal in a manner prohibited by the IHA
(if issued), such as an injury (Level A harassment), serious injury or
mortality (e.g., ship-strike, gear interaction, and/or entanglement),
BP would immediately cease the specified activities and immediately
report the incident to the Chief of the Permits and Conservation
Division, Office of Protected Resources, NMFS, and the Alaska Regional
Stranding Coordinators. The report would include the following
information:
Time, date, and location (latitude/longitude) of the
incident;
Name and type of vessel involved;
Vessel's speed during and leading up to the incident;
Description of the incident;
Status of all sound source use in the 24 hours preceding
the incident;
Water depth;
Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, and visibility);
Description of all marine mammal observations in the 24
hours preceding the incident;
[[Page 21539]]
Species identification or description of the animal(s)
involved;
Fate of the animal(s); and
Photographs or video footage of the animal(s) (if
equipment is available).
Activities would not resume until NMFS is able to review the
circumstances of the prohibited take. NMFS would work with BP to
determine what is necessary to minimize the likelihood of further
prohibited take and ensure MMPA compliance. BP would not be able to
resume their activities until notified by NMFS via letter, email, or
telephone.
In the event that BP 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), BP
would immediately report the incident to the Chief of the Permits and
Conservation Division, Office of Protected Resources, NMFS, and the
NMFS Alaska Stranding Hotline and/or by email to the Alaska Regional
Stranding Coordinators. The report would include the same information
identified in the paragraph above. Activities would be able to continue
while NMFS reviews the circumstances of the incident. NMFS would work
with BP to determine whether modifications in the activities are
appropriate.
In the event that BP 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 the IHA (e.g.,
previously wounded animal, carcass with moderate to advanced
decomposition, or scavenger damage), BP would report the incident to
the Chief of the Permits and Conservation Division, Office of Protected
Resources, NMFS, and the NMFS Alaska Stranding Hotline and/or by email
to the Alaska Regional Stranding Coordinators, within 24 hours of the
discovery. BP would provide photographs or video footage (if available)
or other documentation of the stranded animal sighting to NMFS and the
Marine Mammal Stranding Network.
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 of some species is anticipated as a result of the proposed
shallow geohazard survey. Anticipated impacts to marine mammals are
associated with noise propagation from the sound sources (e.g.,
airguns, sidescan sonar, and subbottom profiler) used in the survey. No
take is expected to result from vessel strikes because of the slow
speed of the vessel (3-4 knots while acquiring seismic data) and
because of mitigation measures to reduce collisions with marine
mammals. Additionally, no take is expected to result from helicopter
operations (if any occur) because of altitude restrictions. No take is
expected from the multibeam echosounder and when the sidescan sonar is
operated at frequencies above 400 kHz because the frequencies are
outside the hearing ranges of marine mammals. Moreover, when the
sidescan sonar is operated at frequencies of 110-135 kHz, it is outside
the hearing ranges of low-frequency cetaceans and ice seals. Therefore,
take has not been estimated from use of these sources for these
species.
BP requested take of 11 marine mammal species by Level B
harassment. However, for reasons mentioned earlier in this document, it
is highly unlikely that humpback and minke whales would occur in the
proposed survey area. Therefore, NMFS does not propose to authorize
take of these two species. The species for which take, by Level B
harassment only, is proposed include: bowhead, beluga, gray, and killer
whales; harbor porpoise; and ringed, bearded, spotted, and ribbon
seals.
The airguns produce impulsive sounds. The current acoustic
thresholds used by NMFS to estimate Level B and Level A harassment are
presented in Table 4.
Table 4--Current Acoustic Exposure Criteria Used by NMFS
------------------------------------------------------------------------
Criterion Criterion definition Threshold
------------------------------------------------------------------------
Level A Harassment (Injury). Permanent Threshold 180 dB re 1 microPa-
Shift (PTS). m (cetaceans)/190
(Any level above dB re 1 microPa-m
that which is known (pinnipeds) root
to cause TTS). mean square (rms).
Level B Harassment.......... Behavioral 160 dB re 1 microPa-
Disruption (for m (rms).
impulse noises).
Level B Harassment.......... Behavioral 120 dB re 1 microPa-
Disruption (for m (rms).
continuous, noise).
------------------------------------------------------------------------
Section 6 of BP's application contains a description of the
methodology used by BP to estimate takes by harassment, including
calculations for the 160 dB (rms) isopleth and marine mammal densities
in the areas of operation (see ADDRESSES), which is also provided in
the following sections. NMFS verified BP's methods, and used the
density and sound isopleth measurements in estimating take. However, as
noted later in this section, NMFS proposes to authorize the maximum
number of estimated takes for all species, not just for cetaceans as
presented by BP in order to ensure that exposure estimates are not
underestimated for pinnipeds.
The shallow geohazard survey will take place in two phases and has
an estimated duration of approximately 20 days, including 5 days
between the two phases where operations will be focused on changing
equipment. Data acquisition will be halted at the start of the Cross
Island fall bowhead whale hunt.
During phase 1 of the project, 2DHR seismic data will be acquired
in about 12 mi\2\ of the Site Survey area. The duration is estimated at
about 7.5 days, based on a continuous 24-hr operation and not including
downtime.
During phase 2, data will be acquired in the Site Survey area (11
mi\2\) and over approximately 5 mi\2\ of the 29 mi\2\ Sonar Survey area
using the multibeam echosounder, sidescan sonar, subbottom profiler,
and magnetometer. The total duration of Phase 2 is also expected to be
7.5 days, based on a continuous 24-hr operation and not including
downtime.
Marine Mammal Density Estimates
Most whale species are migratory and therefore show a seasonal
distribution, with different densities for the summer period (covering
July and August) and the fall period (covering September and October).
Seal species in the Beaufort Sea do not show a distinct seasonal
[[Page 21540]]
distribution during the open-water period between July and October.
Data acquisition of the proposed shallow geohazard survey will only
take place in summer (before start of Nuiqsut whaling in late August/
early September), so BP estimated only summer densities for this
proposed IHA. Whale and seal densities in the Beaufort Sea will further
depend on the presence of sea ice. However, if ice cover within or
close to the seismic survey area is more than approximately 10%, survey
activities may not start or will be halted. Densities related to ice
conditions are therefore not included in the IHA application.
Spatial differentiation is another important factor for marine
mammal densities, both in latitudinal and longitudinal gradient. Taking
into account the shallow water operations of the proposed survey area
and the associated area of influence, BP used data from the nearshore
zone of the Beaufort Sea for the calculation of densities, if
available.
Density estimates are based on best available data. Because
available data did not always cover the area of interest, this is
subject to large temporal and spatial variation, and correction factors
for perception and availability bias were not always known, there is
some uncertainty in the data and assumptions used in the estimated
number of exposures. To provide allowance for these uncertainties,
maximum density estimates have been provided in addition to average
density estimates.
1. Beluga Whale Density Estimates
The 1979-2011 BWASP aerial survey database, available from the NOAA
Web site (http://www.afsc.noaa.gov/NMML/software/bwasp-comida.php),
contains a total of 62 belugas (31 sightings) in block 1, which covers
the nearshore and offshore Prudhoe Bay area. Except for one solitary
animal in 1992, all these belugas were seen in September or October;
the months with most aerial survey effort. None of the sightings
occurred south of 70[deg] N., which is to be expected because beluga
whales generally travel much farther north (Moore et al., 2000). The
summer effort in the 1979-2011 database is limited. Therefore, BP
believes and NMFS agrees that the 2012-2013 data are the best available
for calculating beluga summer densities (Clarke et al., 2013; http://www.asfc.noaa.gov/nmml/cetacean/bwasp/2013), even though the 2013 daily
flight summaries posted on NOAA's Web site have not undergone post-
season QA/QC.
To estimate the density of beluga whales in the Foggy Island Bay
area, BP used the 2012 on-transect beluga sighting and effort data from
the ASAMM surveys flown in July and August in the Beaufort Sea. The
area most applicable to our survey was the area from 140[deg] W.-
154[deg] W. and water depths of 0-20 m (Table 13 in Clarke et al.,
2013). In addition, BP used beluga sighting and effort data of the 2013
survey, as reported in the daily flight summaries on the NOAA Web site.
BP intended to only select flights that covered block 1. However, in
many cases the aerial surveys flown in block 1 also covered blocks 2
and 10, which were much farther from shore. Because it was difficult to
determine the survey effort specific to block 1 from the available
information, BP included the sighting and effort data from block 2 and
10 in the calculations. BP used the number of individuals counted on
transect, together with the transect kilometers flown, to calculate
density estimates (Table 4 in the application and Table 5 here). To
convert the number of individuals per transect kilometer (ind/km) to a
density per area (ind/km\2\), BP used the effective strip width (ESW)
of 0.614 km for belugas calculated from 2008-2012 aerial survey data
flown with the Commander aircraft (M. Ferguson, NMML, pers. comm., 30
Oct 2013).
Table 5--Summary of Beluga Sighting and Effort Data From the 2012 and 2013 ASAMM Aerial Surveys Flown in July
and August in the Beaufort Sea
----------------------------------------------------------------------------------------------------------------
Effort (ind/
Year km) NR. Ind Ind/km Ind/km\2\
----------------------------------------------------------------------------------------------------------------
2012............................................ 1431 5 0.0035 0.0028
2013............................................ 7572 99 0.0131 0.0182
Average......................................... .............. .............. .............. 0.0105
Maximum......................................... .............. .............. .............. 0.0182
Minimum......................................... .............. .............. .............. 0.0028
----------------------------------------------------------------------------------------------------------------
2. Bowhead Whale Density Estimates
To estimate summer bowhead whale densities, BP used data from the
2012 and 2013 ASAMM aerial surveys flown in the Beaufort Sea (Clarke et
al., 2013; www.asfc.noaa.gov/nmml/). The 1979-2011 ASAMM database
contains only one on-transect bowhead whale sighting during July and
August (in 2011), likely due to the limited summer survey effort. In
contrast, the 2012 and 2013 surveys include substantial effort during
the summer season and are thus considered to be the best available
data, even though the 2013 daily flight summaries posted on NOAA's Web
site have not undergone post-season QA/QC.
To estimate the density of bowhead whales in the Foggy Island Bay
area, BP used the 2012 on-transect bowhead sighting and effort data
from surveys flown in July and August in block 1 (Table 4 in Clarke et
al., 2013). In addition, BP used the on-transect bowhead sighting and
effort data of the 2013 survey, as reported in the daily flight
summaries on the NOAA Web site. BP intended to only select flights that
covered block 1. However, in many cases the aerial surveys flown in
block 1 also covered blocks 2 and 10, which were much farther from
shore. Because it was difficult to determine the survey effort specific
to block 1 from the available information, BP included the sighting and
effort data from block 2 and 10 in the calculations (Table 5 in the
application and Table 6 here). To convert the number of individuals per
line transect (ind/km) to a density per area (ind/km\2\), BP used the
ESW of 1.15 km for bowheads, calculated from 2008-2012 aerial survey
data flown with the Commander aircraft (M. Ferguson, NMML, pers. comm.,
30 Oct 2013).
[[Page 21541]]
Table 6--Summary of Bowhead Sighting and Effort Data From the 2012 and 2013 ASAMM Aerial Surveys Flown in July
and August in the Beaufort Sea
----------------------------------------------------------------------------------------------------------------
Effort (ind/
Year km) NR. ind Ind/km Ind/km\2\
----------------------------------------------------------------------------------------------------------------
2012............................................ 1493 5 0.0033 0.0015
2013............................................ 3973 88 0.0221 0.0096
Average......................................... .............. .............. .............. 0.0055
Maximum......................................... .............. .............. .............. 0.0096
Minimum......................................... .............. .............. .............. 0.0015
----------------------------------------------------------------------------------------------------------------
3. Other Whale Species
No densities have been estimated for gray whales and for whale
species that are rare or extralimital to the Beaufort Sea (killer whale
and harbor porpoise) because sightings of these animals have been very
infrequent. Gray whales may be encountered in small numbers throughout
the summer and fall, especially in the nearshore areas. Small numbers
of harbor porpoises may be encountered as well. During an aerial survey
offshore of Oliktok Point in 2008, approximately 40 mi (65 km) west of
the proposed survey area, two harbor porpoises were sighted offshore of
the barrier islands, one on 25 August and the other on 10 September
(Hauser et al., 2008). For the purpose of this IHA request, small
numbers have been included in the requested ``take'' authorization to
cover incidental occurrences of any of these species during the
proposed survey.
4. Seal Density Estimates
Ice seals of the Beaufort Sea are mostly associated with sea ice,
and most census methods count seals when they are hauled out on the
ice. To account for the proportion of animals present but not hauled
out (availability bias) or seals present on the ice but missed
(detection bias), a correction factor should be applied to the ``raw''
counts. This correction factor is dependent on the behavior of each
species. To estimate what proportion of ringed seals were generally
visible resting on the sea ice, radio tags were placed on seals during
spring 1999-2003 (Kelly et al., 2006). The probability that seals were
visible, derived from the satellite data, was applied to seal abundance
data from past aerial surveys and indicated that the proportion of
seals visible varied from less than 0.4 to more than 0.75 between
survey years. The environmental factors that are important in
explaining the availability of seals to be counted were found to be
time of day, date, wind speed, air temperature, and days from snow melt
(Kelly et al., 2006). Besides the uncertainty in the correction factor,
using counts of basking seals from spring surveys to predict seal
abundance in the open-water period is further complicated by the fact
that seal movements differ substantially between these two seasons.
Data from nine ringed seals that were tracked from one subnivean period
(early winter through mid-May or early June) to the next showed that
ringed seals covered large distances during the open-water foraging
period (Kelly et al., 2010b). Ringed seals tagged in 2011 close to
Barrow also show long distances traveled during the open-water season
(Herreman et al., 2012).
To estimate densities for ringed, bearded, and spotted seals, BP
used data collected during four shallow water OBC seismic surveys in
the Beaufort Sea (Harris et al., 2001; Aerts et al., 2008; Hauser et
al., 2008; HDR, 2012). Habitat and survey specifics are very similar to
the proposed survey; therefore, these data were considered to be more
representative than basking seal densities from spring aerial survey
data (e.g., Moulton et al., 2002; Frost et al., 2002, 2004). NMFS
agreed that these data are likely more representative and appropriate
for use. However, since these data were not collected during surveys
designed to determine abundance, NMFS used the maximum estimates for
the proposed number of takes in this proposed IHA.
Because survey effort in kilometers was only reported for one of
the surveys, BP used sighting rate (ind/h) for calculating potential
seal exposures. No distinction is made in seal density between summer
and autumn season. Also, no correction factors have been applied to the
reported seal sighting rates.
Seal species ratios: During the 1996 OBC survey, 92% of all seal
species identified were ringed seals, 7% bearded seals and 1% spotted
seals (Harris et al., 2001). This 1996 survey occurred in two habitats,
one about 19 mi east of Prudhoe Bay near the McClure Islands, mainly
inshore of the barrier islands in water depths of 10 to 26 ft and the
other 6 to 30 mi northwest of Prudhoe Bay, about 0 to 8 mile offshore
of the barrier islands in water depths of 10 to 56 ft (Harris et al.,
2001). In 2008, two OBC seismic surveys occurred in the Beaufort Sea,
one in Foggy Island Bay, about 15 mi SE of Prudhoe Bay (Aerts et al.,
2008), and the other at Oliktok Point, > 30 mi west of Prudhoe Bay
(Hauser et al., 2008). In 2012, an OBC seismic was done in Simpson
Lagoon, bordering the area surveyed in 2008 at Oliktok Point (HDR,
2012). Based on the number of identified individuals the ratio ringed,
bearded, and spotted seal was 75%, 8%, and 17%, respectively in Foggy
Island Bay (Aerts et al., 2008), 22%, 39%, and 39%, respectively at
Oliktok Point (Hauser et al., 2008), and 62%, 15%, and 23%,
respectively in Simpson Lagoon (HDR, 2012). Because it is often
difficult to identify seals to species, a large proportion of seal
sightings were unidentified in all four OBC surveys described here. The
total seal sighting rate was therefore used to calculate densities for
each species, using the average ratio over all four surveys for ringed,
bearded, and spotted seals, i.e., 63% ringed, 17% bearded, and 20%
spotted seals.
Seal sighting rates: During the 1996 OBC survey (Harris et al.,
2001) the sighting rate for all seals during periods when airguns were
not operating was 0.63 ind/h. The sighting rate during non-seismic
periods was 0.046 ind/h for the survey in Foggy Island Bay, just east
of Prudhoe Bay (Aerts et al., 2008). The OBC survey that took place at
Oliktok Point recorded 0.0674 ind/h when airguns were not operating
(Hauser et al., 2008), and the maximum sighting rate during the Simpson
Lagoon OBC seismic survey was 0.030 ind/h (HDR, 2012).
The average seal sighting rate, based on these four surveys, was
0.193 ind/h. The maximum was 0.63 ind/h and the minimum 0.03 ind/h.
Using the proportion of ringed, bearded, and spotted seals as mentioned
above, BP estimated the average and maximum sighting rates (ind/h) for
each of the three seal species (Table 6 in the application and Table 7
here).
[[Page 21542]]
Table 7--Estimated Summer Densities of Whales and Sighting Rates of
Seals (Average and Maximum) for the Proposed Foggy Island Bay Survey.
Densities Are Provided in Number of Individuals Per Square Kilometer
(ind/km\2\), and Sighting Rates Are in Number of Individuals per Hour
(ind/h). No Densities or Sighting Rates Were Estimated for Extralimital
Species
------------------------------------------------------------------------
Summer densities
(ind/km\2\)
Species -------------------
Average Maximum
------------------------------------------------------------------------
Bowhead whale....................................... 0.0015 0.0055
Beluga whale........................................ 0.0028 0.0105
------------------------------------------------------------------------
Summer sighting
rates (ind/h)
-------------------
Average Maximum
------------------------------------------------------------------------
Ringed seal......................................... 0.122 0.397
Bearded seal........................................ 0.033 0.107
Spotted seal........................................ 0.039 0.126
------------------------------------------------------------------------
5. Marine Mammal Density Summary
For the purpose of calculating the potential number of beluga and
bowhead whale exposures to received sound levels of >=160 dB re 1
[mu]Pa, BP used the minimum density from Tables 5 and 6 in this
document as the average density. The reason for this decision is that
the 2012 data only covered block 1 and were considered more
representative. To derive a maximum estimated number of exposures, BP
used the average densities from Tables 5 and 6 in this document. BP
considered this approach reasonable because the 2013 beluga and bowhead
whale sighting data included areas outside the zone of influence of the
proposed project. For example, in 2013, only 3 of the 89 beluga
sightings were seen in block 1. Table 7 in this document summarizes the
densities used in the calculation of potential number of exposures.
Level A and Level B Harassment Zone Distances
For the proposed 2014 shallow geohazard survey, BP used existing
sound source verification (SSV) measurements to establish distances to
received sound pressure levels (SPLs). Airgun arrays consist of a
cluster of independent sources. Because of this, and many other
factors, sounds generated by these arrays therefore do not propagate
evenly in all directions. BP included both broadside and endfire
measurements of the array in calculating distances to the various
received sound levels. Broadside and endfire measurements are not
applicable to mitigation gun measurements.
Seven SSV measurements exist of 20-400 in\3\ airgun arrays in the
shallow water environment of the Beaufort Sea that were considered to
be representative of the proposed 30 in\3\ airgun arrays. These
measurements were from 2008 (n = 4), 2011 (n = 1) and 2012 (n = 2), all
in water depths less than about 50 ft. For the 5 in\3\ mitigation gun,
measured distances of a 10 in\3\ mitigation gun from four shallow
hazard SSV surveys in the Beaufort Sea were used: One in 2007, two in
2008, and one in 2011. Table 7A in BP's application shows average,
maximum, and minimum measured distances to each of the four received
SPL rms levels for 20-40 in\3\ arrays and 10 in\3\ single gun. The
mitigation radii of the proposed 30 in\3\ airgun arrays and 5 in\3\ gun
were derived from the average distance of the 20-40 in\3\ and the 10
in\3\ SSV measurements, respectively (see Table 8 in BP's application).
Distances to sound pressure levels of 190, 180, and 160 dB re 1 [mu]Pa,
generated by the proposed geophysical equipment is much lower than for
airguns (see Table 7B in BP's application). The operating frequency of
the sidescan sonar is within hearing range of toothed whales only, with
a distance of 50 m to 180 dB re 1 [mu]Pa (rms) and 230 m to 160 dB re 1
[mu]Pa (rms) (Warner & McCrodan, 2011). Sounds generated by the
subbottom profiler are within the hearing range of all marine mammal
species occurring in the area but do not produce sounds strong enough
to reach sound pressure levels of 190 or 180 dB re 1 [mu]Pa (rms). The
distance to 160 dB re 1 [mu]Pa (rms) is estimated at 30 m (Warner &
McCrodan, 2011). BP considered the distances derived from the existing
airgun arrays as summarized in Table 7A in BP's application as
representative for the proposed 30 in\3\ arrays. NMFS concurs with this
approach.
Table 8 in this document presents the radii used to estimate take
(160 dB isopleth) and to implement mitigation measures (180 dB and 190
dB isopleths) from the full airgun array and the 5 in\3\ mitigation
gun. However, take is only estimated using the larger radius of the
full airgun array.
Table 8--Distances (in Meters) To Be Used For Estimating Take by Level B Harassment and for Mitigation Purposes
During the Proposed 2014 North Prudhoe Bay 2014 Seismic Survey
----------------------------------------------------------------------------------------------------------------
Airgun discharge volume (in\3\) 190 dB re 1 [micro]Pa 180 dB re 1 [micro]Pa 160 dB re 1 [micro]Pa
----------------------------------------------------------------------------------------------------------------
30 in\3\............................. 70 200 1,600
5 in\3\.............................. 20 50 600
----------------------------------------------------------------------------------------------------------------
Numbers of Marine Mammals Potentially Taken by Harassment
The potential number of marine mammals that might be exposed to the
160 dB re 1 [micro]Pa (rms) SPL was calculated differently for
cetaceans and pinnipeds, as described in Section 6.3 of BP's
application and next here. BP did not calculate take from the subbottom
profiler or from the sidescan sonar for toothed whales. Based on the
distance to the 160 dB re 1 [micro]Pa (rms) isopleths for these sources
and the fact that NMFS proposes to authorize the maximum estimated
exposure estimate, the extremely minimal number of exposures that would
result from use of these sources is already accounted for in the airgun
exposure estimates.
1. Number of Cetaceans Potentially Taken by Harassment
The potential number of bowhead and beluga whales that might be
exposed to the 160 dB re 1 [mu]Pa (rms) sound pressure level was
calculated by multiplying:
The expected bowhead and beluga density as provided in
Tables 5 and 6 in this document (Tables 4 and 5 in BP's application);
The anticipated area around each source vessel that is
ensonified by the 160 dB re 1 [mu]Pa (rms) sound pressure level; and
The estimated number of 24-hr days that the source vessels
are operating.
The area expected to be ensonified by the 30 in\3\ array was
determined based on the maximum distance to the 160 dB re 1 [mu]Pa
(rms) SPL as determined from the maximum 20-40 in\3\ array measurements
(Table 7A in BP's application), which is 1.6 km. Based on
[[Page 21543]]
a radius of 1.6 km, the 160 dB isopleth used in the exposure
calculations was 8 km\2\.
The estimated number of 24-hr days of airgun operations is 7.5 days
(180 hours), not including downtime. Downtime is related to weather,
equipment maintenance, mitigation implementation, and other
circumstances.
Average and maximum estimates of the number of bowhead and beluga
whales potentially exposed to sound pressure levels of 160 dB re
1[mu]Pa (rms) or more are summarized in Table 9 in BP's application.
Species such as gray whale, killer whale, and harbor porpoise are not
expected to be encountered but might be present in very low numbers;
the maximum expected number of exposures for these species provided in
Table 9 of BP's application is based on the likelihood of incidental
occurrences.
The average and maximum number of bowhead whales potentially
exposed to sound levels of 160 dB re 1[mu]Pa (rms) or more is estimated
at 0 and 1, respectively. BP requested to take three bowheads to
account for chance encounters. The average and maximum number of
potential beluga exposures to 160 dB is 0 and 1, respectively. Belugas
are known to show aggregate behavior and can occur in large numbers in
nearshore zones, as evidenced by the sighting at Endicott in August
2013. Therefore, for the unlikely event that a group of belugas appears
within the 160 dB isopleth during the proposed seismic survey, BP added
a number of 75 to the requested authorization. Chance encounters with
small numbers of other whale species are possible.
These estimated exposures do not take into account the proposed
mitigation measures, such as PSOs watching for animals, shutdowns or
power downs of the airguns when marine mammals are seen within defined
ranges, and ramp-up of airguns.
2. Number of Pinnipeds Potentially Taken by Harassment
The estimated number of seals that might be exposed to pulsed
sounds of 160 dB re 1 [mu]Pa (rms) was calculated by multiplying:
The expected species specific sighting rate as provided in
Table 7 in this document (also in Table 6 in BP's application); and
The total number of hours that each source vessel will be
operating during the data acquisition period.
The estimated number of hours that airguns will be operating is 180
hours (7.5 days of 24 hour operations). The resulting average and
maximum number of ringed, bearded, and spotted seal exposures based on
180 hours of airgun operations are summarized in Table 9 of BP's
application. BP assumed that all seal sightings would occur within the
160 dB isopleth. These estimated exposures do not take into account the
proposed mitigation measures, such as PSOs watching for animals,
shutdowns or power downs of the airguns when marine mammals are seen
within defined ranges, and ramp-up of airguns.
Estimated Take by Harassment Summary
Table 9 here outlines the density estimates used to estimate Level
B takes, the proposed Level B harassment take levels, the abundance of
each species in the Beaufort Sea, the percentage of each species or
stock estimated to be taken, and current population trends. As
explained earlier in this document, NMFS used the maximum density
estimates or sighting rates and proposes to authorize the maximum
estimates of exposures. Additionally, as explained earlier, density
estimates are not available for species that are uncommon in the
proposed survey area.
Table 9--Density Estimates or Species Sighting Rates, Proposed Level B Harassment Take Levels, Species or Stock Abundance, Percentage of Population
Proposed To Be Taken, and Species Trend Status
--------------------------------------------------------------------------------------------------------------------------------------------------------
Density
Species (/ Sighting rate Proposed Level Abundance Percentage of Trend
km\2\) (ind/hr) B take population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Beluga whale.............................. 0.0105 .............. 75 39,258 0.19 No reliable information.
Killer whale.............................. NA .............. 1 552 0.18 Stable.
Harbor porpoise........................... NA .............. 1 48,215 >0.01 No reliable information.
Bowhead whale............................. 0.0055 .............. 3 16,892 0.02 Increasing.
Gray whale................................ NA .............. 1 19,126 0.01 Increasing.
Bearded seal.............................. .............. 0.107 19 155,000 0.01 No reliable information.
Ringed seal............................... .............. 0.397 71 300,000 0.02 No reliable information.
Spotted seal.............................. .............. 0.126 23 141,479 0.02 No reliable information.
Ribbon seal............................... .............. NA 1 49,000 >0.01 No reliable information.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Analysis and Preliminary Determinations
Negligible Impact
Negligible impact is ``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'' (50 CFR 216.103). A
negligible impact finding is based on the lack of likely adverse
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of Level B harassment takes,
alone, is not enough information on which to base an impact
determination. In addition to considering estimates of the number of
marine mammals that might be ``taken'' through behavioral harassment,
NMFS must consider other factors, such as the likely nature of any
responses (their intensity, duration, etc.), the context of any
responses (critical reproductive time or location, migration, etc.), as
well as the number and nature of estimated Level A harassment takes,
the number of estimated mortalities, effects on habitat, and the status
of the species.
No injuries or mortalities are anticipated to occur as a result of
BP's proposed shallow geohazard survey, and none are proposed to be
authorized. Additionally, animals in the area are not expected to incur
hearing impairment (i.e., TTS or PTS) or non-auditory physiological
effects. The number of takes that are anticipated and authorized are
expected to be limited to short-term Level B behavioral harassment.
While the airguns will be operated continuously for about 7.5 days, the
project time frame will occur when cetacean species are typically not
found in the project area or are found only in low numbers. While
pinnipeds are likely to be found in the proposed project area more
frequently, their distribution is dispersed enough that they likely
will not be in the Level B harassment zone continuously. As mentioned
previously in this document, pinnipeds appear to be more tolerant of
anthropogenic sound than mystiectes.
[[Page 21544]]
The use of sidescan sonar, multibeam echosounder, and subbottom
profiler continuously for 7.5 days will not negatively impact marine
mammals as the majority of these instruments are operated outside of
the hearing frequencies of marine mammals.
The Alaskan Beaufort Sea is part of the main migration route of the
Western Arctic stock of bowhead whales. However, the seismic survey has
been planned to occur when the majority of the population is found in
the Canadian Beaufort Sea. Operation of airguns and other sound sources
will cease by midnight on August 25 before the main fall migration
begins and well before cow/calf pairs begin migrating through the area.
Additionally, several locations within the Beaufort Sea serve as
feeding grounds for bowhead whales. However, as mentioned earlier in
this document, the primary feeding grounds are not found in Foggy
Island Bay. The majority of bowhead whales feed in the Alaskan Beaufort
Sea during the fall migration period, which will occur after the
cessation of the survey.
Belugas that migrate through the U.S. Beaufort Sea typically do so
farther offshore (more than 37 mi [60 km]) and in deeper waters (more
than 656 ft [200 m]) than where the proposed survey activities would
occur. Gray whales are rarely sighted this far east in the U.S.
Beaufort Sea. Additionally, there are no known feeding grounds for gray
whales in the Foggy Island Bay area. The most northern feeding sites
known for this species are located in the Chukchi Sea near Hanna Shoal
and Point Barrow. The other cetacean species for which take is proposed
are uncommon in Foggy Island Bay, and no known feeding or calving
grounds occur in Foggy Island Bay for these species. Based on these
factors, exposures of cetaceans to anthropogenic sounds are not
expected to last for prolonged periods (i.e., several days) since they
are not known to remain in the area for extended periods of time in
July and August. Also, the shallow water location of the survey makes
it unlikely that cetaceans would remain in the area for prolonged
periods. Based on all of this information, the proposed project is not
anticipated to affect annual rates of recruitment or survival for
cetaceans in the area.
Ringed seals breed and pup in the Alaskan Beaufort Sea; however,
the proposed survey will occur outside of the breeding and pupping
seasons. The Beaufort Sea does not provide suitable habitat for the
other three ice seal species for breeding and pupping. Based on this
information, the proposed project is not anticipated to affect annual
rates of recruitment or survival for pinnipeds in the area.
Of the nine marine mammal species for which take is authorized, one
is listed as endangered under the ESA--the bowhead whale--and two are
listed as threatened--ringed and bearded seals. Schweder et al. (2009)
estimated the yearly growth rate to be 3.2% (95% CI = 0.5-4.8%) between
1984 and 2003 using a sight-resight analysis of aerial photographs.
There are currently no reliable data on trends of the ringed and
bearded seal stocks in Alaska. The ribbon seal is listed as a species
of concern under the ESA. Certain stocks or populations of gray,
killer, 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 activity area. There is currently no
established critical habitat in the project area for any of these nine
species.
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 monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from BP's proposed shallow geohazard survey in Foggy Island
Bay, Beaufort Sea, Alaska, will have a negligible impact on the
affected marine mammal species or stocks.
Small Numbers
The requested takes proposed to be authorized represent less than
1% of all populations or stocks (see Table 9 in this document). These
take estimates represent the percentage of each species or stock that
could be taken by Level B behavioral harassment if each animal is taken
only once. The numbers of marine mammals taken are small relative to
the affected species or stock sizes. In addition, 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. NMFS preliminarily
finds that small numbers of marine mammals will be taken relative to
the populations of 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 the proposed survey 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.
Residents of the village of Nuiqsut are the primary subsistence
users in the project area. The communities of Barrow and Kaktovik also
harvest resources that pass through the area of interest but do not
hunt in or near the Foggy Island Bay area. Subsistence hunters from all
three communities conduct an annual hunt for autumn-migrating bowhead
whales. Barrow also conducts a bowhead hunt in spring. Residents of all
three communities hunt seals. Other subsistence activities include
fishing, waterfowl and seaduck harvests, and hunting for walrus, beluga
whales, polar bears, caribou, and moose.
Nuiqsut is the community closest to the seismic survey area
(approximately 73 mi [117.5 km] southwest). Nuiqsut hunters harvest
bowhead whales only during the fall whaling season (Long, 1996). In
recent years, Nuiqsut whalers have typically landed three or four
whales per year. Nuiqsut whalers concentrate their efforts on areas
north and east of Cross Island, generally in water depths greater than
66 ft (20 m; Galginaitis, 2009). Cross Island is the principal base for
Nuiqsut whalers while they are hunting bowheads (Long, 1996). Cross
Island is located approximately 10 mi (16 km) from the closest boundary
of the survey area.
Kaktovik whalers search for whales east, north, and occasionally
west of Kaktovik. Kaktovik is located approximately 91 mi (146.5 km)
east of Foggy Island Bay. The western most reported harvest location
was about 13 mi (21 km) west of Kaktovik, near 70[deg]10' N.,
144[deg]11' W. (Kaleak, 1996). That site is about 80 mi (129 km) east
of the proposed survey area.
Barrow whalers search for whales much farther from the Foggy Island
Bay area--about 200+ mi (322+ km) to the west. Barrow hunters have
expressed
[[Page 21545]]
concerns about ``downstream'' effects to bowhead whales during the
westward fall migration; however, BP will cease airgun operations prior
to the start of the fall migration.
Beluga whales are not a prevailing subsistence resource in the
communities of Kaktovik and Nuiqsut. Kaktovik hunters may harvest one
beluga whale in conjunction with the bowhead hunt; however, it appears
that most households obtain beluga through exchanges with other
communities. Although Nuiqsut hunters have not hunted belugas for many
years while on Cross Island for the fall hunt, this does not mean that
they may not return to this practice in the future. Data presented by
Braund and Kruse (2009) indicate that only 1% of Barrow's total harvest
between 1962 and 1982 was of beluga whales and that it did not account
for any of the harvested animals between 1987 and 1989.
Ringed seals are available to subsistence users in the Beaufort Sea
year-round, but they are primarily hunted in the winter or spring due
to the rich availability of other mammals in the summer. Bearded seals
are primarily hunted during July in the Beaufort Sea; however, in 2007,
bearded seals were harvested in the months of August and September at
the mouth of the Colville River Delta, which is approximately 50+ mi
(80+ km) from the proposed survey area. However, this sealing area can
reach as far east as Pingok Island, which is approximately 20 mi (32
km) west of the survey area. An annual bearded seal harvest occurs in
the vicinity of Thetis Island (which is a considerable distance from
Foggy Island Bay) in July through August. Approximately 20 bearded
seals are harvested annually through this hunt. Spotted seals are
harvested by some of the villages in the summer months. Nuiqsut hunters
typically hunt spotted seals in the nearshore waters off the Colville
River Delta. The majority of the more established seal hunts that occur
in the Beaufort Sea, such as the Colville delta area hunts, are located
a significant distance (in some instances 50 mi [80 km] or more) from
the project area.
Potential Impacts to Subsistence Uses
NMFS has defined ``unmitigable adverse impact'' in 50 CFR 216.103
as: ``. . . an impact resulting from the specified activity: (1) That
is likely to reduce the availability of the species to a level
insufficient for a harvest to meet subsistence needs by: (i) Causing
the marine mammals to abandon or avoid hunting areas; (ii) Directly
displacing subsistence users; or (iii) Placing physical barriers
between the marine mammals and the subsistence hunters; and (2) 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 BP's proposed shallow geohazard
survey have the potential to impact marine mammals hunted by Native
Alaskan. In the case of cetaceans, the most common reaction to
anthropogenic sounds (as noted previously) 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, although not really anticipated, 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, such as tail-slapping, which translate to
danger for nearby subsistence harvesters.
Plan of Cooperation or Measures To Minimize Impacts to Subsistence
Hunts
Regulations at 50 CFR 216.104(a)(12) require IHA applicants for
activities that take place in Arctic waters to provide a Plan of
Cooperation 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. BP has begun
discussions with the Alaska Eskimo Whaling Commission (AEWC) to develop
a Conflict Avoidance Agreement (CAA) intended to minimize potential
interference with bowhead subsistence hunting. BP also attended and
participated in meetings with the AEWC on December 13, 2013, and will
attend future meetings to be scheduled in 2014. The CAA, when executed,
will describe measures to minimize any adverse effects on the
availability of bowhead whales for subsistence uses.
The North Slope Borough Department of Wildlife Management (NSB-DWM)
will be consulted, and BP plans to present the project to the NSB
Planning Commission in 2014. BP will hold meetings in the community of
Nuiqsut to present the proposed project, address questions and concerns
from community members, and provide them with contact information of
project management to which they can direct concerns during the survey.
During the NMFS Open-Water Meeting in Anchorage in 2013, BP presented
their proposed projects to various stakeholders that were present
during this meeting.
BP will continue to engage with the affected subsistence
communities regarding its Beaufort Sea activities. As in previous
years, BP will meet formally and/or informally with several stakeholder
entities: The NSB Planning Department, NSB-DWM, NMFS, AEWC, Inupiat
Community of the Arctic Slope, Inupiat History Language and Culture
Center, USFWS, Nanuq and Walrus Commissions, and Alaska Department of
Fish & Game.
Project information was provided to and input on subsistence
obtained from the AEWC and Nanuq Commission at the following meetings:
AEWC, October 17, 2013; and
Nanuq Commission, October 17, 2013.
Additional meetings with relevant stakeholders will be scheduled
and a record of attendance and topics discussed will be maintained and
submitted to NMFS.
BP proposes to implement several mitigation measures to reduce
impacts on the availability of marine mammals for subsistence hunts in
the Beaufort Sea. Many of these measures were developed from the 2013
CAA and previous NSB Development Permits. In addition to the measures
listed next, BP will cease all airgun operations by midnight on August
25 to allow time for the Beaufort Sea communities to prepare for their
fall bowhead whale hunts prior to the beginning of the fall westward
migration through the Beaufort Sea. Some of the measures mentioned next
have been mentioned previously in this document:
PSOs on board vessels are tasked with looking out for
whales and other marine mammals in the vicinity of the vessel to assist
the vessel captain in avoiding harm to whales and other marine
mammals.;
Vessels and aircraft will avoid areas where species that
are sensitive to noise or vessel movements are concentrated;
Communications and conflict resolution are detailed in the
CAA. BP will participate in the Communications Center that is operated
annually during the bowhead subsistence hunt;
Communications with the village of Nuiqsut to discuss
community questions or concerns including all subsistence hunting
activities. Pre-project meeting(s) with Nuiqsut
[[Page 21546]]
representatives will be held at agreed times with groups in the
community of Nuiqsut. If additional meetings are requested, they will
be set up in a similar manner;
Contact information for BP will be provided to community
members and distributed in a manner agreed at the community meeting;
BP has contracted with a liaison from Nuiqsut who will
help coordinate meetings and serve as an additional contact for local
residents during planning and operations; and
Inupiat Communicators will be employed and work on seismic
source vessels. They will also serve as PSOs.
Unmitigable Adverse Impact Analysis and Preliminary Determination
BP has adopted a spatial and temporal strategy for its Foggy Island
Bay survey that should minimize impacts to subsistence hunters. First,
BP's activities will not commence until after the spring hunts have
occurred. Second, BP will cease all airgun operations by midnight on
August 25 prior to the start of the bowhead whale fall westward
migration and any fall subsistence hunts by Beaufort Sea communities.
Foggy Island Bay is not commonly used for subsistence hunts. Although
some seal hunting co-occurs temporally with BP's proposed survey, the
locations do not overlap. BP's presence will not place physical
barriers between the sealers and the seals. Additionally, BP will work
closely with the closest affected communities and support
Communications Centers and employ local Inupiat Communicators. Based on
the description of the specified activity, the measures described to
minimize adverse effects on the availability of marine mammals for
subsistence purposes, and the proposed mitigation and monitoring
measures, NMFS has preliminarily determined that there will not be an
unmitigable adverse impact on subsistence uses from BP's proposed
activities.
Endangered Species Act (ESA)
Within the project area, the bowhead whale is listed as endangered
and the ringed and bearded seals are listed as threatened under the
ESA. NMFS' Permits and Conservation Division has initiated consultation
with staff in NMFS' Alaska Region Protected Resources Division under
section 7 of the ESA on the issuance of an IHA to BP 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 conducting an analysis, pursuant to NEPA, to
determine whether this proposed IHA may have a significant effect on
the human environment. This analysis will be completed prior to the
issuance or denial of this proposed IHA.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to BP for conducting a shallow geohazard survey in the
Foggy Island Bay area of the Beaufort Sea, Alaska, during the 2014
open-water season, provided the previously mentioned mitigation,
monitoring, and reporting requirements are incorporated. The proposed
IHA language is provided next.
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 IHA is valid from July 1, 2014, through September 30, 2014.
2. This IHA is valid only for activities associated with open-water
shallow geohazard surveys and related activities in the Beaufort Sea.
The specific areas where BP's surveys will be conducted are within the
Foggy Island Bay Area, Beaufort Sea, Alaska, as shown in Figure 1 of
BP's IHA application.
3. Species Authorized and Level of Take:
a. The incidental taking of marine mammals, by Level B harassment
only, is limited to the following species in the waters of the Beaufort
Sea:
i. Odontocetes: 75 Beluga whales; 1 killer whale; and 1 harbor
porpoise.
ii. Mysticetes: 3 Bowhead whales and 1 gray whale.
iii. Pinnipeds: 71 Ringed seals; 19 bearded seals; 23 spotted
seals; and 1 ribbon seal.
iv. If any marine mammal species not listed in conditions 3(a)(i)
through (iii) are encountered during seismic survey operations and are
likely to be exposed to sound pressure levels (SPLs) greater than or
equal to 160 dB re 1 [micro]Pa (rms) for impulse sources, then the
Holder of this IHA must shut-down the sound source to avoid take.
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 IHA.
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. 30 in\3\ airgun arrays;
b. 10 in\3\ and/or 5 in\3\ mitigation airguns; and
c. Vessel activities related to the OBS seismic survey.
5. The taking of any marine mammal in a manner prohibited under
this Authorization must be reported within 24 hours of the taking to
the Alaska Regional Administrator or his designee and the Chief of the
Permits and Conservation Division, Office of Protected Resources, NMFS,
or her designee.
6. The holder of this Authorization must notify the Chief of the
Permits and Conservation Division, Office of Protected Resources, at
least 48 hours prior to the start of collecting seismic data (unless
constrained by the date of issuance of this IHA in which case
notification shall be made as soon as possible).
7. Mitigation Requirements: The Holder of this Authorization is
required to implement the following mitigation requirements when
conducting the specified activities to achieve the least practicable
impact on affected marine mammal species or stocks:
a. General Vessel and Aircraft Mitigation
i. Avoid concentrations or groups of whales by all vessels under
the direction of BP. Operators of support vessels should, at all times,
conduct their activities at the maximum distance possible from such
concentrations of whales.
ii. The vessel shall be operated at speeds necessary to ensure no
physical contact with whales occurs. If the vessel approaches within
1.6 km (1 mi) of observed whales, except when providing emergency
assistance to whalers or in other emergency situations, the vessel
operator will take reasonable precautions to avoid potential
interaction with the whales by taking one or more of the following
actions, as appropriate:
A. Reducing vessel speed to less than 5 knots within 300 yards (900
feet or 274 m) of the whale(s);
B. Steering around the whale(s) if possible;
C. Operating the vessel(s) in such a way as to avoid separating
members of a group of whales from other members of the group;
D. Operating the vessel(s) to avoid causing a whale to make
multiple changes in direction;
E. Checking the waters immediately adjacent to the vessel(s) to
ensure that
[[Page 21547]]
no whales will be injured when the propellers are engaged; and
F. Reducing vessel speed to less than 9 knots when weather
conditions reduce visibility.
iii. When weather conditions require, such as when visibility
drops, adjust vessel speed accordingly to avoid the likelihood of
injury to whales.
iv. In the event that any aircraft (such as helicopters) are used
to support the planned survey, the mitigation measures below would
apply:
A. Under no circumstances, other than an emergency, shall aircraft
be operated at an altitude lower than 1,000 feet above sea level when
within 0.3 mile (0.5 km) of groups of whales.
B. Helicopters shall not hover or circle above or within 0.3 mile
(0.5 km) of groups of whales.
C. At all other times, aircraft should attempt not to fly below
1,000 ft except during emergencies and take-offs and landings.
b. Seismic Airgun Mitigation
i. Whenever a marine mammal is detected outside the exclusion zone
radius and based on its position and motion relative to the ship track
is likely to enter the exclusion radius, calculate and implement an
alternative ship speed or track or de-energize the airgun array, as
described in condition 7(b)(iv) below.
ii. Exclusion Zones:
A. Establish and monitor with trained PSOs an exclusion zone for
cetaceans surrounding the airgun array on the source vessel where the
received level would be 180 dB re 1 [micro]Pa rms. This radius is
estimated to be 200 m from the seismic source for the 30 in\3\ airgun
arrays and 50 m for a single 5 in\3\ airgun.
B. Establish and monitor with trained PSOs an exclusion zone for
pinnipeds surrounding the airgun array on the source vessel where the
received level would be 190 dB re 1 [micro]Pa rms. This radius is
estimated to be 70 m from the seismic source for the 30 in\3\ airgun
arrays and 20 m for a single 5 in\3\ airgun.
iii. Ramp-up:
A. A ramp-up, following a cold start, can be applied if the
exclusion zone has been free of marine mammals for a consecutive 30-
minute period. The entire exclusion zone must have been visible during
these 30 minutes. If the entire exclusion zone is not visible, then
ramp-up from a cold start cannot begin.
B. Ramp-up procedures from a cold start shall be delayed if a
marine mammal is sighted within the exclusion zone during the 30-minute
period prior to the ramp up. The delay shall last until the marine
mammal(s) has been observed to leave the exclusion zone or until the
animal(s) is not sighted for at least 15 or 30 minutes. The 15 minutes
applies to pinnipeds, while a 30 minute observation period applies to
cetaceans.
C. A ramp-up, following a shutdown, can be applied if the marine
mammal(s) for which the shutdown occurred has been observed to leave
the exclusion zone or until the animal(s) is not sighted for at least
15 minutes (pinnipeds) or 30 minutes (cetaceans).
D. If, for any reason, electrical power to the airgun array has
been discontinued for a period of 10 minutes or more, ramp-up
procedures shall be implemented. Only if the PSO watch has been
suspended, a 30-minute clearance of the exclusion zone is required
prior to commencing ramp-up. Discontinuation of airgun activity for
less than 10 minutes does not require a ramp-up.
E. The seismic operator and PSOs shall maintain records of the
times when ramp-ups start and when the airgun arrays reach full power.
F. The ramp-up will be conducted by doubling the number of
operating airguns at 5-minute intervals, starting with the smallest gun
in the array.
iv. Power-down/Shutdown:
A. The airgun array shall be immediately powered down (reduction in
the number of operating airguns such that the radii of exclusion zones
are decreased) whenever a marine mammal is sighted approaching close to
or within the applicable exclusion zone of the full array, but is
outside the applicable exclusion zone of the single mitigation airgun.
B. If a marine mammal is already within the exclusion zone when
first detected, the airguns shall be powered down immediately.
C. Following a power-down, ramp-up to the full airgun array shall
not resume until the marine mammal has cleared the exclusion zone. The
animal will be considered to have cleared the exclusion zone if it is
visually observed to have left the exclusion zone of the full array, or
has not been seen within the zone for 15 minutes (pinnipeds) or 30
minutes (cetaceans).
D. If a marine mammal is sighted within or about to enter the 190
or 180 dB (rms) applicable exclusion zone of the single mitigation
airgun, the airgun array shall be shutdown immediately.
E. Airgun activity after a complete shutdown shall not resume until
the marine mammal has cleared the exclusion zone of the full array. The
animal will be considered to have cleared the exclusion zone as
described above under ramp-up procedures.
v. Poor Visibility Conditions:
A. If during foggy conditions, heavy snow or rain, or darkness, the
full 180 dB exclusion zone is not visible, the airguns cannot commence
a ramp-up procedure from a full shut-down.
B. If one or more airguns have been operational before nightfall or
before the onset of poor visibility conditions, they can remain
operational throughout the night or poor visibility conditions. In this
case ramp-up procedures can be initiated, even though the exclusion
zone may not be visible, on the assumption that marine mammals will be
alerted by the sounds from the single airgun and have moved away.
C. The mitigation airgun will be operated at approximately one shot
per minute and will not be operated for longer than three hours in
duration during daylight hours and good visibility. In cases when the
next start-up after the turn is expected to be during lowlight or low
visibility, use of the mitigation airgun may be initiated 30 minutes
before darkness or low visibility conditions occur and may be operated
until the start of the next seismic acquisition line. The mitigation
gun must still be operated at approximately one shot per minute.
c. Subsistence Mitigation
i. Airgun and echosounder, sonar, and subbottom profiler operations
must cease no later than midnight on August 25, 2014;
ii. BP will participate in the Communications Center that is
operated annually during the bowhead subsistence hunt; and
iii. Inupiat communicators will work on the seismic vessels.
8. Monitoring
a. The holder of this Authorization must designate biologically-
trained, on-site individuals (PSOs) to be onboard the source vessels,
who are approved in advance by NMFS, to conduct the visual monitoring
programs required under this Authorization and to record the effects of
seismic surveys and the resulting sound on marine mammals.
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.
ii. Crew leaders and most other biologists serving as observers
will be individuals with experience as observers during recent seismic
or shallow hazards monitoring projects in
[[Page 21548]]
Alaska, the Canadian Beaufort, or other offshore areas in recent years.
iii. PSOs shall complete a training session on marine mammal
monitoring, to be conducted shortly before the anticipated start of the
2014 open-water season. The training session(s) will be conducted by
qualified marine mammalogists with extensive crew-leader experience
during previous vessel-based monitoring programs. An observers'
handbook, adapted for the specifics of the planned survey program will
be reviewed as part of the training.
iv. 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.
v. Crew members should not be used as primary PSOs because they
have other duties and generally do not have the same level of
expertise, experience, or training as PSOs, but they could be stationed
on the fantail of the vessel to observe the near field, especially the
area around the airgun array and implement a power-down or shutdown if
a marine mammal enters the exclusion zone).
vi. If crew members are to be used as PSOs, they shall go through
some basic training consistent with the functions they will be asked to
perform. The best approach would be for crew members and PSOs to go
through the same training together.
vii. 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.
viii. BP shall train its PSOs to follow a scanning schedule that
consistently distributes scanning effort according to the purpose and
need for observations. For example, the schedule might call for 60% of
scanning effort to be directed toward the near field and 40% at the far
field. All PSOs should follow the same schedule to ensure consistency
in their scanning efforts.
ix. PSOs shall be trained in documenting the behaviors of marine
mammals. PSOs should simply record the primary behavioral state (i.e.,
traveling, socializing, feeding, resting, approaching or moving away
from vessels) and relative location of the observed marine mammals.
b. To the extent possible, PSOs should be on duty for four (4)
consecutive hours or less, although more than one four-hour shift per
day is acceptable; however, an observer shall not be on duty for more
than 12 hours in a 24-hour period.
c. Monitoring is to be conducted by the PSOs onboard the active
seismic vessels to ensure that no marine mammals enter the appropriate
exclusion zone whenever the seismic acoustic sources are on and to
record marine mammal activity as described in condition 8(f). Two PSOs
will be present on the vessel. At least one PSO shall monitor for
marine mammals at any time during daylight hours.
d. At all times, the crew must be instructed to keep watch for
marine mammals. If any are sighted, the bridge watch-stander must
immediately notify the PSO(s) on-watch. If a marine mammal is within or
closely approaching its designated exclusion zone, the seismic acoustic
sources must be immediately powered down or shutdown (in accordance
with condition 7(b)(iv)).
e. Observations by the PSOs on marine mammal presence and activity
will begin a minimum of 30 minutes prior to the estimated time that the
seismic source is to be turned on and/or ramped-up.
f. All marine mammal observations and any airgun power-down, shut-
down and ramp-up will be recorded in a standardized format. Data will
be entered into a custom database. The accuracy of the data entry will
be verified daily through QA/QC procedures. These procedures will allow
initial summaries of data to be prepared during and shortly after the
field program, and will facilitate transfer of the data to other
programs for further processing and archiving.
g. Monitoring shall consist of recording:
i. The species, group size, age/size/sex categories (if
determinable), the general behavioral activity, heading (if
consistent), bearing and distance from seismic vessel, sighting cue,
behavioral pace, and apparent reaction of all marine mammals seen near
the seismic vessel and/or its airgun array (e.g., none, avoidance,
approach, paralleling, etc);
ii. The time, location, heading, speed, and activity of the vessel
(shooting or not), along with sea state, visibility, cloud cover and
sun glare at:
A. Any time a marine mammal is sighted (including pinnipeds hauled
out on barrier islands),
B. At the start and end of each watch, and
C. During a watch (whenever there is a change in one or more
variable);
iii. The identification of all vessels that are visible within 5 km
of the seismic vessel whenever a marine mammal is sighted, and the time
observed, bearing, distance, heading, speed and activity of the other
vessel(s);
iv. Any identifiable marine mammal behavioral response (sighting
data should be collected in a manner that will not detract from the
PSO's ability to detect marine mammals);
v. Any adjustments made to operating procedures; and
iv. Visibility during observation periods so that total estimates
of take can be corrected accordingly.
h. BP shall work with its observers to develop a means for
recording data that does not reduce observation time significantly.
i. PSOs shall use the best possible positions for observing (e.g.,
outside and as high on the vessel as possible), taking into account
weather and other working conditions. PSOs shall carefully document
visibility during observation periods so that total estimates of take
can be corrected accordingly.
j. PSOs shall scan systematically with the unaided eye and reticle
binoculars, and other devices.
k. PSOs shall attempt to maximize the time spent looking at the
water and guarding the exclusion radii. They shall avoid the tendency
to spend too much time evaluating animal behavior or entering data on
forms, both of which detract from their primary purpose of monitoring
the exclusion zone.
l. Night-vision equipment (Generation 3 binocular image
intensifiers, or equivalent units) shall be available for use during
low light hours, and BP shall continue to research methods of detecting
marine mammals during periods of low visibility.
m. PSOs shall understand the importance of classifying marine
mammals as ``unknown'' or ``unidentified'' if they cannot identify the
animals to species with confidence. In those cases, they shall note any
information that might aid in the identification of the marine mammal
sighted. For example, for an unidentified mysticete whale, the
observers should record whether the animal had a dorsal fin.
n. Additional details about unidentified marine mammal sightings,
such as ``blow only'', mysticete with (or without) a dorsal fin, ``seal
splash'', etc., shall be recorded.
o. BP shall conduct a fish and airgun sound monitoring program as
described in the IHA application and further refined in consultation
with an expert panel.
9. Data Analysis and Presentation in Reports:
a. Estimation of potential takes or exposures shall be improved for
times with low visibility (such as during fog
[[Page 21549]]
or darkness) through interpolation or possibly using a probability
approach. Those data could be used to interpolate possible takes during
periods of restricted visibility.
b. Water depth should be continuously recorded by the vessel and
for each marine mammal sighting. Water depth should be accounted for in
the analysis of take estimates.
c. BP shall be very clear in their report about what periods are
considered ``non-seismic'' for analyses.
d. BP shall examine data from ASAMM and other such programs to
assess possible impacts from their seismic survey.
e. To better assess impacts to marine mammals, data analysis shall
be separated into periods when a seismic airgun array (or a single
mitigation airgun) is operating and when it is not. Final and
comprehensive reports to NMFS should summarize and plot:
i. Data for periods when a seismic array is active and when it is
not; and
ii. The respective predicted received sound conditions over fairly
large areas (tens of km) around operations.
f. To help evaluate the effectiveness of PSOs and more effectively
estimate take, if appropriate data are available, BP shall perform
analysis of sightability curves (detection functions) for distance-
based analyses.
g. BP should improve take estimates and statistical inference into
effects of the activities by incorporating the following measures:
i. Reported results from all hypothesis tests should include
estimates of the associated statistical power when practicable.
ii. 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.
10. Reporting Requirements: The Holder of this Authorization is
required to:
a. A report will be submitted to NMFS within 90 days after the end
of the proposed seismic survey. The report will summarize all
activities and monitoring results conducted during in-water seismic
surveys. The Technical Report will include the following:
i. Summary of project start and end dates, airgun activity, number
of guns, and the number and circumstances of implementing ramp-up,
power down, shutdown, and other mitigation actions;
ii. 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);
iii. Analyses of the effects of various factors influencing
detectability of marine mammals (e.g., sea state, number of observers,
and fog/glare);
iv. Species composition, occurrence, and distribution of marine
mammal sightings, including date, water depth, numbers, age/size/gender
categories (if determinable), and group sizes;
v. Analyses of the effects of survey operations;
vi. Sighting rates of marine mammals during periods with and
without seismic survey activities (and other variables that could
affect detectability), such as:
A. Initial sighting distances versus survey activity state;
B. Closest point of approach versus survey activity state;
C. Observed behaviors and types of movements versus survey activity
state;
D. Numbers of sightings/individuals seen versus survey activity
state;
E. Distribution around the source vessels versus survey activity
state; and
F. Estimates of exposures of marine mammals to Level B harassment
thresholds based on presence in the 160 dB harassment zone.
b. 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.
c. BP will present the results of the fish and airgun sound study
to NMFS in a detailed report.
11. Notification of Dead or Injured Marine Mammals
a. In the unanticipated event that the specified activity clearly
causes the take of a marine mammal in a manner prohibited by the IHA,
such as an injury (Level A harassment), serious injury or mortality
(e.g., ship-strike, gear interaction, and/or entanglement), BP would
immediately cease the specified activities and immediately report the
incident to the Chief of the Permits and Conservation Division, Office
of Protected Resources, NMFS, and the Alaska Regional Stranding
Coordinators. The report would include the following information:
Time, date, and location (latitude/longitude) of the
incident;
Name and type of vessel involved;
Vessel's speed during and leading up to the incident;
Description of the incident;
Status of all sound source use in the 24 hours preceding
the incident;
Water depth;
Environmental conditions (e.g., wind speed and direction,
Beaufort sea state, cloud cover, and visibility);
Description of all marine mammal observations in the 24
hours preceding the incident;
Species identification or description of the animal(s)
involved;
Fate of the animal(s); and
Photographs or video footage of the animal(s) (if
equipment is available).
Activities would not resume until NMFS is able to review the
circumstances of the prohibited take. NMFS would work with BP to
determine what is necessary to minimize the likelihood of further
prohibited take and ensure MMPA compliance. BP would not be able to
resume their activities until notified by NMFS via letter, email, or
telephone.
b. In the event that BP 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), BP
would immediately report the incident to the Chief of the Permits and
Conservation Division, Office of Protected Resources, NMFS, and the
NMFS Alaska Stranding Hotline and/or by email to the Alaska Regional
Stranding Coordinators. The report would include the same information
identified in the paragraph above. Activities would be able to continue
while NMFS reviews the circumstances of the incident. NMFS would work
with BP to determine whether modifications in the activities are
appropriate.
c. In the event that BP 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 the IHA (e.g.,
previously wounded animal, carcass with moderate to advanced
decomposition, or scavenger damage), BP would report the incident to
the Chief of the Permits and Conservation Division, Office of Protected
Resources, NMFS, and the NMFS Alaska Stranding Hotline and/or by email
to the Alaska Regional Stranding Coordinators, within 24 hours of the
discovery. BP would provide photographs or video footage (if available)
or other documentation of the stranded animal sighting to NMFS and the
Marine Mammal Stranding Network.
12. Activities related to the monitoring described in this IHA do
not require a separate scientific research
[[Page 21550]]
permit issued under section 104 of the MMPA.
13. BP is required to comply with the Reasonable and Prudent
Measures and Terms and Conditions of the Incidental Take Statement
(ITS) corresponding to NMFS' Biological Opinion.
14. A copy of this IHA and the ITS must be in the possession of all
contractors and PSOs operating under the authority of this IHA.
15. 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.
16. 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.
Request for Public Comments
NMFS requests comment on our analysis, the draft authorization, and
any other aspect of the Notice of Proposed IHA for BP's proposed
shallow geohazard survey in the Foggy Island Bay area of the Beaufort
Sea, Alaska, during the 2014 open-water season. Please include with
your comments any supporting data or literature citations to help
inform our final decision on BP's request for an MMPA authorization.
Dated: April 10, 2014.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2014-08534 Filed 4-15-14; 8:45 am]
BILLING CODE 3510-22-P