[Federal Register Volume 78, Number 34 (Wednesday, February 20, 2013)]
[Notices]
[Pages 11821-11844]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-03837]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XC389
Takes of Marine Mammals Incidental to Specified Activities; Low-
Energy Marine Geophysical Survey in the Gulf of Mexico, April to May,
2013
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 the U.S. Geological
Survey (USGS), for an Incidental Harassment Authorization (IHA) to take
marine mammals, by harassment, incidental to conducting a low-energy
marine geophysical (seismic) survey in the Gulf of Mexico, April to
May, 2013. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is
requesting comments on its proposal to issue an IHA to USGS to
incidentally harass, by Level B harassment only, 19 species of marine
mammals during the specified activity.
DATES: Comments and information must be received no later than March
22, 2013.
ADDRESSES: Comments on the application should be addressed to P.
Michael Payne, Chief, Permits and Conservation Division, Office of
Protected Resources, National Marine Fisheries Service, 1315 East-West
Highway, Silver Spring, MD 20910. The mailbox address for providing
email comments is [email protected]. NMFS is not responsible for
email comments sent to addresses other than the one provided here.
Comments sent via email, including all attachments, must not exceed a
10-megabyte file size.
All comments received are a part of the public record and will
generally be
[[Page 11822]]
posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications without change. All Personal Identifying
Information (for example, name, address, etc.) voluntarily submitted by
the commenter may be publicly accessible. Do not submit confidential
business information or otherwise sensitive or protected information.
A copy of the application containing a list of the references used
in this document may be obtained by writing to the above address,
telephoning the contact listed here (see FOR FURTHER INFORMATION
CONTACT) or visiting the internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
The USGS has prepared a draft ``Environmental Assessment and
Determination Pursuant to the National Environmental Policy Act, 42
U.S.C. 4321 et seq. and Executive Order 12114 Low-Energy Marine Seismic
Survey by the U.S. Geological Survey in the Deepwater Gulf of Mexico,
April-May 2013'' (EA). USGS's EA incorporates a draft ``Environmental
Assessment of a Low-Energy Marine Geophysical Survey by the U.S.
Geological Survey in the Northwestern Gulf of Mexico, April-May
2013,'', prepared by LGL Ltd., Environmental Research Associates, on
behalf of USGS, which is also available at the same Internet address.
Documents cited in this notice may be viewed, by appointment, during
regular business hours, at the aforementioned address.
FOR FURTHER INFORMATION CONTACT: Howard Goldstein or Jolie Harrison,
Office of Protected Resources, NMFS, 301-427-8401.
SUPPLEMENTARY INFORMATION:
Background
Section 101(a)(5)(D) of the MMPA, as amended (16 U.S.C. 1371
(a)(5)(D)), directs the Secretary of Commerce (Secretary) to authorize,
upon request, the incidental, but not intentional, taking of small
numbers of marine mammals of a species or population stock, by United
States citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and, if the taking is limited to harassment, a notice
of a proposed authorization is provided to the public for review.
Authorization for the incidental taking of small numbers of marine
mammals shall be granted if NMFS finds that the taking will have a
negligible impact on the species or stock(s), and will not have an
unmitigable adverse impact on the availability of the species or
stock(s) for subsistence uses (where relevant). The authorization must
set forth the permissible methods of taking, other means of effecting
the least practicable adverse impact on the species or stock and its
habitat, and requirements pertaining to the mitigation, monitoring and
reporting of such takings. NMFS has defined ``negligible impact'' in 50
CFR 216.103 as ``[hellip]an impact resulting from the specified
activity that cannot be reasonably expected to, and is not reasonably
likely to, adversely affect the species or stock through effects on
annual rates of recruitment or survival.''
Section 101(a)(5)(D) of the MMPA established an expedited process
by which citizens of the United States can apply for an authorization
to incidentally take small numbers of marine mammals by harassment.
Section 101(a)(5)(D) of the MMPA establishes a 45-day time limit for
NMFS's review of an application followed by a 30-day public notice and
comment period on any proposed authorizations for the incidental
harassment of small numbers of marine mammals. Within 45 days of the
close of the public comment period, NMFS must either issue or deny the
authorization.
Except with respect to certain activities not pertinent here, the
MMPA defines ``harassment'' as: any act of pursuit, torment, or
annoyance which (i) has the potential to injure a marine mammal or
marine mammal stock in the wild [Level A harassment]; or (ii) has the
potential to disturb a marine mammal or marine mammal stock in the wild
by causing disruption of behavioral patterns, including, but not
limited to, migration, breathing, nursing, breeding, feeding, or
sheltering [Level B harassment].
Summary of Request
On November 5, 2012, NMFS received an application from the USGS
requesting that NMFS issue an IHA for the take, by Level B harassment
only, of small numbers of marine mammals incidental to conducting a
low-energy marine seismic survey within the U.S. Exclusive Economic
Zone in the deep water of the Gulf of Mexico during April to May 2013.
The USGS plans to use one source vessel, the R/V Pelican (Pelican), or
similar vessel, and a seismic airgun array to collect seismic data as
part of the ``Gas Hydrates Project'' in the deep water of the northwest
Gulf of Mexico. The USGS plans to use conventional low-energy, seismic
methodology and ocean bottom seismometers (OBSs) to acquire the data
necessary to delineate the distribution, saturation, and thickness of
sub-seafloor methane hydrates and to image near-seafloor structure
(e.g., faults) at high-resolution. In addition to the proposed
operations of the seismic airgun array and hydrophone streamer, USGS
intends to operate a sub-bottom profiler continuously throughout the
survey.
Acoustic stimuli (i.e., increased underwater sound) generated
during the operation of the seismic airgun array may have the potential
to cause a behavioral disturbance for marine mammals in the survey
area. This is the principal means of marine mammal taking associated
with these activities, and USGS has requested an authorization to take
19 species of marine mammals by Level B harassment. Take is not
expected to result from the use of the sub-bottom profiler, for reasons
discussed in this notice; nor is take expected to result from collision
with the source vessel because it is a single vessel moving at a
relatively slow speed (4.5 knots [kts]; 8.1 kilometers per hour [km/
hr]; 5.0 miles per hour [mph]) during seismic acquisition within the
survey, for a relatively short period of time (approximately 8 days of
airgun operations out of 15 total operational days). It is likely that
any marine mammal would be able to avoid the vessel.
Description of the Proposed Specified Activity
USGS proposes to conduct a low-energy seismic survey at two sites
that have been studied as part of the Gulf of Mexico Gas Hydrates Joint
Industry Project. The GC955 (i.e., Green Canyon lease block 955) and
WR313 (i.e., Walker Ridge lease block 313) study sites are located in
the deep water of the northwestern GOM (see Figure 1 of the IHA
application). Study site GC955 will be surveyed first, followed by
WR313. The seismic survey is scheduled to take place for approximately
eight days (out of 15 total operational days) in April to May 2013.
The purpose of USGS's proposed seismic survey is to develop
technology and to collect data to assist in the characterization of
marine gas hydrates in order to better understand their impact on
seafloor stability, their role in climate change, and their potential
as an energy source. These sites have been extensively studied,
including detailed logging while drilling (LWD), and are known to hold
thick sequences of sand containing high saturations of gas hydrate. The
purpose of this new seismic acquisition is to expand outward from the
boreholes the detailed characterization that has been accomplished
there and to develop and calibrate improved geophysical
[[Page 11823]]
techniques for gas hydrate characterization.
The proposed survey will involve one source vessel, most likely the
R/V Pelican (Pelican) or a similar vessel. USGS will deploy two (each
with a discharge volume of 105 cubic inch [in\3\]) Generator Injector
(GI) airgun array as a primary energy source at a tow depth of 3 m (9.8
ft). A subset of the survey lines will be repeated using either a
single 35 in\3\ GI airgun. The receiving system will consist of one 450
meter (m) (1,476.4 feet [ft]) long, 72-channel hydrophone streamer and
25 ocean bottom seismometers (OBSs). As the GI airguns are towed along
the survey lines, the hydrophone streamer will receive the returning
acoustic signals and transfer the data to the onboard processing
system. The OBSs record the returning acoustic signals internally for
later analysis. Regardless of which energy source is used, the
calculated isopleths for the two GI (105 in\3\) airguns will be used.
At each of the two study sites, 25 OBSs will be deployed and a
total of approximately 700 km (378 nautical miles [nmi]) of survey
lines will be collected in a grid pattern (see Figure 1 of the IHA
application). The water depth will be 1,500 to 2,000 m (4,921.3 to
6,561.7 ft) at each study site). All planned seismic data acquisition
activities will be conducted by technicians provided by USGS with
onboard assistance by the scientists who have proposed the study. The
Principal Investigators are Dr. Seth Haines (USGS Energy Program,
Denver, Colorado) and Mr. Patrick Hart (USGS Coastal and Marine
Geology, Santa Cruz, California). The vessel will be self-contained,
and the crew will live aboard the vessel for the entire cruise.
The planned seismic survey (e.g., equipment testing, startup, line
changes, repeat coverage of any areas, and equipment recovery) will
consist of approximately 1,480 km (799.1 nmi) of transect lines
(including turns) in the survey area in the deep water of the
northwestern Gulf of Mexico (GOM) (see Figure 1 of the IHA
application). In addition to the operation of the airgun array, a
Knudsen sub-bottom profiler will also likely be operated from the
Pelican continuously throughout the cruise. USGS will not be operating
a multibeam system, the Pelican is not equipped with this equipment.
There will be additional seismic operations associated with equipment
testing, ramp-up, and possible line changes or repeat coverage of any
areas where initial data quality is sub-standard. In USGS's estimated
take calculations, 25% has been added for those additional operations.
Vessel Specifications
The Pelican (although a similar vessel might be used for this
proposed program), a research vessel owned by the Louisiana
Universities Marine Consortium (LUMCON), will tow the two GI airgun
array, as well as the hydrophone streamer, along predetermined lines
(see Figure 1 of the IHA application). When the Pelican is towing the
airgun array and the relatively short hydrophone streamer, the turning
rate of the vessel while the gear is deployed is limited to better than
5 degrees per a minute (this is higher than a seismic vessel towing a
streamer of more typical length much greater than 1 km [0.5 nmi]). The
LUMCON Marine Superintendent estimates that the turning radius of the
Pelican will be approximately 500 m (1,640.4 ft) while the vessel is
towing the hydrophone streamer. Thus, the maneuverability of the vessel
is not limited much during operations with the streamer. The vessel
would ``fly'' the appropriate U.S. Coast Guard-approved day shapes
(mast head signals used to communicate with other vessels) and display
the appropriate lighting to designate the vessel has limited
maneuverability.
The vessel has a length of 33.5 m (109.9 ft); a beam of 8.0 m (26.3
ft); a full load draft of 2.9 m (9.5 ft); and a gross tonnage of 261.
The ship is equipped with two Caterpillar Model 3412 1648 in\3\ diesel
engines and an 80 horsepower (hp) Schottel bowthruster. Electrical
power is provided by two Caterpillar 3306, 99 kiloWatt (kW) diesel
generators. The Pelican's operation speed during seismic acquisition is
typically approximately 8.1 km per hour (hr) (km/hr) (4.5 knots [kts]).
When not towing seismic survey gear, the Pelican typically cruises at
17 km/hr (9.2 kts). The Pelican has an operating range of approximately
5,600 km (3,023.8 nmi) (the distance the vessel can travel without
refueling).
The vessel also has two locations as likely observation stations
from which Protected Species Observers (PSO) will watch for marine
mammals before and during the proposed airgun operations on the
Pelican. When stationed on the observation platforms, the PSO's eye
level will be approximately 12 m (39.4 ft) above sea level providing
the PSO an approximately 210[deg] view aft of the vessel from the aft
control station, and from the bridge station the PSO's eye level will
be approximately 13 m (42.7 ft) above sea level providing the PSO an
unobstructed 360[deg] view around the entire vessel. More details of
the Pelican can be found in the IHA application.
Acoustic Source Specifications
Seismic Airguns
The Pelican (or similar vessel) will deploy an airgun array,
consisting of two 105 in\3\ Sercel GI airguns as the primary energy
source and a streamer containing hydrophones along predetermined lines.
A subset of the survey lines will be repeated using a single 35 in\3\
GI airgun. The airgun array will have a firing pressure of 2,000 pounds
per square inch (psi). Discharge intervals depend on both the ship's
speed and Two Way Travel Time recording intervals. Seismic pulses for
the GI airguns will be emitted at intervals of approximately 6 to 10
seconds. At speeds of approximately 8.1 km/hr, the shot intervals
correspond to spacing of approximately will be 14 to 23 m (45.9 to 75.5
ft) during the study. During firing, a brief (approximately 0.03
second) pulse sound is emitted; the airguns will be silent during the
intervening periods. The dominant frequency components range from zero
to 188 Hertz (Hz).
The generator chamber of each GI airgun in the primary source, the
one responsible for introducing the sound pulse into the ocean, is 105
in\3\. The injector chamber injects air into the previously-generated
bubble to maintain its shape, and does not introduce more sound into
the water. The two GI airguns will be towed 8 m (26.2 ft) apart, side-
by-side, 21 m (68.9 ft) behind the Pelican, at a depth of 3 m (9.8 ft)
during the surveys. The total effective volume will be 210 in\3\.
The single 35 in\3\ GI airgun is the same type of dual chamber
airgun as the 105 in\3\ GI airgun described above, with the generator
and injector chambers each being 35 in\3\. The manufacturer's
literature indicates that a 35 in\3\ GI airgun has a root mean square
(rms) source level of approximately 208 dB re 1 [mu]Pam, a duration of
about 10 ms, and dominant frequency components of less than 500 Hz.
Field measurements by USGS personnel indicate that the GI airgun
outputs low sound amplitudes at frequencies greater than 500 Hz. The 35
in\3\ GI airgun will be towed approximately 15 m (49.2 ft) behind the
ship at approximately 2 m (6.6 ft) depth.
As the GI airgun(s) is towed along the survey line, the towed
hydrophone array in the streamer receives the reflected signals and
transfers the data to the on-board processing system. The OBSs record
the returning acoustic signals internally for later analysis. Given the
relatively short streamer
[[Page 11824]]
length behind the vessel, the turning rate of the vessel while the gear
is deployed is much higher than the limit of five degrees per minute
for a seismic vessel towing a streamer of more typical length (i.e.,
much greater than 1 km [0.54 nmi]). Thus, the maneuverability of the
vessel is not limited much during seismic operations.
Metrics Used in This Document
This section includes a brief explanation of the sound measurements
frequently used in the discussions of acoustic effects in this
document. Sound pressure is the sound force per unit area, and is
usually measured in micropascals ([mu]Pa), where 1 pascal (Pa) is the
pressure resulting from a force of one newton exerted over an area of
one square meter. Sound pressure level (SPL) is expressed as the ratio
of a measured sound pressure and a reference level. The commonly used
reference pressure level in underwater acoustics is 1 [mu]Pa, and the
units for SPLs are dB re: 1 [mu]Pa. SPL (in decibels [dB]) = 20 log
(pressure/reference pressure).
SPL is an instantaneous measurement and can be expressed as the
peak, the peak-peak (p-p), or the rms. Root mean square (rms), which is
the square root of the arithmetic average of the squared instantaneous
pressure values, is typically used in discussions of the effects of
sounds on vertebrates and all references to SPL in this document refer
to the root mean square unless otherwise noted. SPL does not take the
duration of a sound into account.
Characteristics of the Airgun Pulses
Airguns function by venting high-pressure air into the water which
creates an air bubble. The pressure signature of an individual airgun
consists of a sharp rise and then fall in pressure, followed by several
positive and negative pressure excursions caused by the oscillation of
the resulting air bubble. The oscillation of the air bubble transmits
sounds downward through the seafloor and the amount of sound
transmitted in the near horizontal directions is reduced. However, the
airgun array also emits sounds that travel horizontally toward non-
target areas.
The nominal downward-directed source levels of the airgun arrays
used by USGS on the Pelican do not represent actual sound levels that
can be measured at any location in the water. Rather they represent the
level that would be found 1 m (3.3 ft) from a hypothetical point source
emitting the same total amount of sound as is emitted by the combined
GI airguns. The actual received level at any location in the water near
the GI airguns will not exceed the source level of the strongest
individual source. In this case, that will be about 234.4 dB re 1
[micro]Pam peak, or 239.8 dB re 1 [micro]Pam peak-to-peak. However, the
difference between rms and peak or peak-to-peak values for a given
pulse depends on the frequency content and duration of the pulse, among
other factors. Actual levels experienced by any organism more than 1 m
from either GI airgun will be significantly lower.
Accordingly, Lamont-Doherty Earth Observatory of Columbia
University (L-DEO) has predicted the received sound levels in relation
to distance and direction from the two GI airgun array. A detailed
description of L-DEO's modeling for this survey's marine seismic source
arrays for protected species mitigation is provided in the NSF/USGS
PEIS. These are the nominal source levels applicable to downward
propagation. The NSF/USGS PEIS discusses the characteristics of the
airgun pulses. NMFS refers the reviewers to that documents for
additional information.
Predicted Sound Levels for the Airguns
To determine exclusion zones for the airgun array to be used in the
deep water of the GOM, received sound levels have been modeled by L-DEO
for a number of airgun configurations, including two 105 in\3\ GI
airguns, in relation to distance and direction from the airguns (see
Figure 2 of the IHA application). The model does not allow for bottom
interactions, and is most directly applicable to deep water. Based on
the modeling, estimates of the maximum distances from the GI airguns
where sound levels of 190, 180, and 160 dB re 1 [micro]Pa (rms) are
predicted to be received in deep water are shown in Table 1 (see Table
1 of the IHA application). Received sound levels have not been modeled
for the single 35 in\3\ GI airgun, but maximum distances for that
source would be much lower than those for the two 105 in\3\ GI airguns.
USGS and NMFS will use the results for the two 105 in\3\ GI airguns for
all seismic lines, resulting in conservative (precautionary for marine
mammals) results when the smaller sources are used.
Empirical data concerning the 190, 180, and 160 dB (rms) distances
were acquired for various airgun arrays based on measurements during
the acoustic verification studies conducted by L-DEO in the northern
GOM in 2003 (Tolstoy et al., 2004) and 2007 to 2008 (Tolstoy et al.,
2009). Results of the 36 airgun array are not relevant for the two GI
airguns to be used in the proposed survey. The empirical data for the
6, 10, 12, and 20 airgun arrays indicate that, for deep water, the L-
DEO model tends to overestimate the received sound levels at a given
distance (Tolstoy et al., 2004). Measurements were not made for the two
GI airgun array in deep water; however, USGS proposes to use the buffer
and exclusion zones predicted by L-DEO's model for the proposed GI
airgun operations in deep water, although they are likely conservative
given the empirical results for the other arrays. Using the L-DEO
model, Table 1 (below) shows the distances at which three rms sound
levels are expected to be received from the two GI airguns. The 180 and
190 dB re 1 [micro]Pam (rms) distances are the safety criteria for
potential Level A harassment as specified by NMFS (2000) and are
applicable to cetaceans and pinnipeds, respectively. If marine mammals
are detected within or about to enter the appropriate exclusion zone,
the airguns will be shut-down immediately. Table 1 summarizes the
predicted distances at which sound levels (160, 180, and 190 dB [rms])
are expected to be received from the two GI airgun array operating in
deep water depths.
Table 1 summarizes the predicted distances at which sound levels
(160, 180, and 190 dB [rms]) are expected to be received from the two
airgun array operating in deep water (greater than 1,000 m [3,280 ft])
depths. For the proposed project, USGS plans to use the distances for
the two 105 in\3\ GI airguns for the single 35 in\3\ GI airgun, for the
determination of the buffer and exclusion zones since this represents
the largest and therefore most conservative distances determined by the
model results provided by L-DEO.
Table 1. Modeled (two 105 in\3\ GI airgun array) distances to which
sound levels >= 190, 180, and 160 dB re: 1 [mu]Pa (rms) could be
received in deep water during the proposed survey in the northwestern
GOM, April to May, 2013.
[[Page 11825]]
----------------------------------------------------------------------------------------------------------------
Predicted RMS radii distances (m) for 2
airgun array
Source and volume Tow depth (m) Water depth (m) --------------------------------------------
160
190 dB 180 dB dB
----------------------------------------------------------------------------------------------------------------
Two GI Airguns (105 in\3\)..... 3 Deep (> 1,000).... 20 m.............. 70 m.............. 670
(65.6 ft)......... (229.7 ft)........ m
(2,
198
.2
ft)
----------------------------------------------------------------------------------------------------------------
Along with the airgun operations, one additional acoustical data
acquisition systems may be operated from the Pelican continuously
during the survey. A hull-mounted Knudsen 3.5 kHz sub-bottom profiler
(successor to model 320B) may be available since the Pelican is
considering such an installation in the coming months. They have not
yet chosen the exact equipment. The ocean floor may be mapped with the
Knudsen sub-bottom profiler. If the sub-bottom profiler is available,
USGS will use it if it provides quality supplemental information that
enhances the higher-energy (i.e., GI airguns) surveys or site
characterization in the immediate vicinity of an OBS deployment. This
sound source would be operated continuously from the Pelican throughout
the cruise.
Sub-Bottom Profiler
The Pelican may operate a Knudsen 3.5 kHz sub-bottom continuously
throughout the cruise simultaneously to map and provide information
about the sedimentary features and bottom topography. The beam of the
sub-bottom profiler is transmitted as a 27[deg] cone, which is directed
downward by a 3.5 kHz transducer in the hull of the Pelican. The
maximum output is 1 kilowatt (kW) (approximately 204 dB re: 1 [mu]Pam),
but in practice, the output varies with water depth. Pulse duration is
1, 2, or 4 milliseconds (ms).
The sub-bottom profiler is operated continuously during survey
operations. Power levels of the instrument would be modified to account
for water depth. Actual operating parameters will be established at the
time of the survey. This type of 3.5 kHz system falls within Appendix F
(low-energy) of the NSF/USGS PEIS.
NMFS expects that acoustic stimuli resulting from the proposed
operation of the two GI airgun array has the potential to harass marine
mammals., NMFS does not expect that the movement of the Pelican, during
the conduct of the seismic survey, has the potential to harass marine
mammals because of the relatively slow operation speed of the vessel
(approximately 4.5 knots [kts]; 8.3 km/hr; 5.2 mph) during seismic
acquisition.
Ocean Bottom Seismometers
For the proposed study, 25 OBSs will be deployed from the Pelican
at each of the two study sites in sequence (see Figure 1 of the IHA
application). Once the seismic surveys have been completed at the first
site, the OBSs will be retrieved, then re-deployed at the second site.
Once the seismic surveys have been completed at the second site, OBSs
will be retrieved. OBSs operated by the U.S. National OBS Instrument
Pool will be used during the proposed cruise. This type of OBS has a
height of approximately 1 m (3.3 ft) and a maximum diameter of 50
centimeters (cm) (19.7 inches [in]). The anchor is a steel plate
weighing approximately 40 kilograms (kg) (88.2 pounds [lb]) with
dimensions approximately 30x30x8 cm (11.8x11.8x3.1 in). Once an OBS is
ready to be retrieved, an acoustic release transponder interrogates the
instrument at a frequency of 9 to 11 kiloHertz (kHz), and a response is
received at a frequency of 9 to 13 kHz. The burn-wire release assembly
is then activated, and the instrument is released from the anchor to
float to the surface.
Dates, Duration, and Specified Geographic Region
The proposed project will be located near the GC955 and WR313 study
sites in the deep water of the northwest Gulf of Mexico and would have
a total duration of approximately 15 operational days occurring during
the April through May 2013 timeframe, which will include approximately
8 days of active seismic airgun operations. Water depth at the site is
approximately 2,000 m (6561.7 ft). The total survey time would be
approximately 96 hours at each site. The proposed survey is scheduled
from April 16 to May 5, 2013. The Pelican is expected to depart and
return to Cocodrie, Louisiana, with no intermediate stops.
Some minor deviation from this schedule is possible, depending on
logistics and weather (i.e., the cruise may depart earlier or be
extended due to poor weather; there could be additional days of seismic
operations if collected data are deemed to be of substandard quality).
The latitude and longitude for the bounds of the two study sites
are:
WR313:
91[deg] 34.75' West to 91[deg] 46.75' West
26[deg] 33.75' North to 26[deg] 45.75' North
GC955:
90[deg] 20.0' West to 90[deg] 31.75' West
26[deg] 54.1' North to 27[deg] 6.0' North
Description of the Marine Mammals in the Area of the Proposed Specified
Activity
The marine mammal species that potentially occur within the GOM
include 28 species of cetaceans and one sirenian (Jefferson and Schiro,
1997; Wursig et al., 2000; see Table 2 below). In addition to the 28
species known to occur in the GOM, the long-finned pilot whale
(Globicephala melas), long-beaked common dolphin (Delphinus capensis),
and short-beaked common dolphin (Delphinus delphis) could potentially
occur there. However, there are no confirmed sightings of these species
in the GOM, but they have been seen close and could eventually be found
there (Wursig et al., 2000). Those three species are not considered
further in this document. The marine mammals that generally occur in
the proposed action area belong to three taxonomic groups: mysticetes
(baleen whales), odontocetes (toothed whales), and sirenians (the West
Indian manatee). Of the marine mammal species that potentially occur
within the GOM, 21 species of cetaceans (20 odontocetes, 1 mysticete)
are routinely present and have been included in the analysis for
incidental take to the proposed seismic survey. Marine mammal species
listed as endangered under the U.S. Endangered Species Act of 1973
(ESA; 16 U.S.C. 1531 et seq.), includes the North Atlantic right
(Eubalaena glacialis), humpback (Megaptera novaeangliae), sei
(Balaenoptera borealis), fin (Balaenoptera physalus), blue
(Balaenoptera musculus), and sperm (Physeter macrocephalus) whale, as
well as the West Indian (Florida) manatee (Trichechus manatus
latirostris). Of those endangered species, only the sperm whale is
likely to be encountered in the proposed survey area. No species of
pinnipeds are known to occur regularly in the GOM, and any pinniped
sighted in the proposed study area would be considered extralimital.
The Caribbean monk seal (Monachus tropicalis) used to inhabit the GOM
but is considered extinct and has been
[[Page 11826]]
delisted from the ESA. The West Indian manatee is the one marine mammal
species mentioned in this document that is managed by the U.S. Fish and
Wildlife Service (USFWS) and is not considered further in this
analysis; all others are managed by NMFS.
In general, cetaceans in the GOM appear to be partitioned by
habitat preferences likely related to prey distribution (Baumgartner et
al., 2001). Most species in the northern GOM concentrated along the
upper continental slope in or near areas of cyclonic circulation in
waters 200 to 1,000 m (656.2 to 3,280.8 ft) deep. Species sighted
regularly in these waters include Risso's, rough-toothed, spinner,
striped, pantropical spotted, and Clymene dolphins, as well as short-
finned pilot, pygmy and dwarf sperm, sperm, Mesoplodon beaked, and
unidentified beaked whales (Davis et al., 1998). In contrast,
continental shelf waters (< 200 m deep) are primarily inhabited by two
species: bottlenose and Atlantic spotted dolphins (Davis et al., 2000,
2002; Mullin and Fulling, 2004). Bottlenose dolphins are also found in
deeper waters (Baumgartner et al., 2001). The narrow continental shelf
south of the Mississippi River delta (20 km [10.8 nmi] wide at its
narrowest point) appears to be an important habitat for several
cetacean species (Baumgartner et al., 2001; Davis et al., 2002). There
appears to be a resident population of sperm whales within 100 km (54
nmi) of the Mississippi River delta (Davis et al., 2002).
Table 2 (below) presents information on the abundance,
distribution, population status, conservation status, and population
trend of the species of marine mammals that may occur in the proposed
study area during April to May, 2013.
Table 2--The Habitat, Regional Abundance, and Conservation Status of Marine Mammals That May Occur in or Near
the Proposed Seismic Survey Area in the Deep Water of the Northwest Gulf of Mexico
[See text and Table 2 in USGS's application for further details.]
----------------------------------------------------------------------------------------------------------------
Population
Species Habitat estimate\3\ ESA \1\ MMPA \2\ Population
(minimum) Trend \3\
----------------------------------------------------------------------------------------------------------------
Mysticetes
----------------------------------------------------------------------------------------------------------------
North Atlantic right whale Coastal and Extralimital... EN........... D.............. Increasing.
(Eubalaena glacialis). shelf.
Humpback whale (Megaptera Pelagic, Rare........... EN........... D.............. Increasing.
novaeangliae). nearshore
waters, and
banks.
Minke whale (Balaenoptera Pelagic and Rare........... NL........... NC............. No information
acutorostrata). coastal. available.
Bryde's whale (Balaenoptera Pelagic and 15 (5)-- NL........... NC............. Unable to
brydei). coastal. Northern GOM determine.
stock.
Sei whale (Balaenoptera Primarily Rare........... EN........... D.............. Unable to
borealis). offshore, determine.
pelagic.
Fin whale (Balaenoptera Continental Rare........... EN........... D.............. Unable to
physalus). slope, pelagic. determine.
Blue whale (Balaenoptera Pelagic, shelf, Extralimital... EN........... D.............. Unable to
musculus). coastal. determine.
----------------------------------------------------------------------------------------------------------------
Odontocetes
----------------------------------------------------------------------------------------------------------------
Sperm whale (Physeter Pelagic, deep 1,665 (1,409)-- EN........... D.............. Unable to
macrocephalus). sea. Northern GOM determine.
stock.
Pygmy sperm whale (Kogia Deep waters off 323 (203)-- NL........... NC............. Unable to
breviceps). the shelf. Northern GOM determine.
stock.
Dwarf sperm whale (Kogia Deep waters off 453 (340)-- NL........... NC............. Unable to
sima). the shelf. Northern GOM determine.
stock.
Cuvier's beaked whale Pelagic........ 65 (39)-- NL........... NC............. Unable to
(Ziphius cavirostris). Northern GOM determine.
stock.
Mesoplodon beaked whale Pelagic........ 57 (24)-- NL........... NC............. Unable to
(includes Blainville's Northern GOM determine.
beaked whale [M. stock.
densirostris], Gervais'
beaked whale [M. europaeus],
and Sowerby's beaked whale
[M. bidens].
Killer whale (Orcinus orca).. Pelagic, shelf, 49 (28)-- NL........... NC............. Unable to
coastal. Northern GOM determine.
stock.
Short-finned pilot whale..... Pelagic, shelf 716 (542)-- NL........... NC............. Unable to
(Globicephala macrorhynchus). coastal. Northern GOM determine.
stock.
False killer whale (Pseudorca Pelagic........ 777 (501)-- NL........... NC............. Unable to
crassidens). Northern GOM determine.
stock.
Melon-headed whale Pelagic........ 2,283 (1,293)-- NL........... NC............. Unable to
(Peponocephala electra). Northern GOM determine.
stock.
Pygmy killer whale (Feresa Pelagic........ 323 (203)-- NL........... NC............. Unable to
attenuata). Northern GOM determine.
stock.
Risso's dolphin (Grampus Deep water, 1,589 (1,271)-- NL........... NC............. Unable to
griseus). seamounts. Northern GOM determine.
stock.
[[Page 11827]]
Bottlenose dolphin (Tursiops Offshore, NA (NA)--32 NL........... NC............. Unable to
truncatus). inshore, Northern GOM S--32 stocks determine.
coastal, Bay, Sound and inhabitiing
estuaries. Estuary stocks. the bays,
NA (NA)-- sounds, and
Northern GOM estuaries
continental along GOM
shelf stock. coast, and GOM
7,702 (6,551)-- western
GOM eastern coastal stock.
coastal stock.
2,473 (2,004)--
GOM northern
coastal stock.
NA (NA)--GOM
western
coastal stock.
3,708 (2,641)--
Northern GOM
oceanic stock.
Rough-toothed dolphin (Steno Pelagic........ 2,653 (1,890)-- NL........... NC............. Unable to
bredanensis). Northern GOM determine.
stock.
Fraser's dolphin Pelagic........ Unknown NL........... NC............. Unable to
(Lagenodelphis hosei). (Unkown)--Nort determine.
hern GOM stock.
Striped dolphin (Stenella Pelagic........ 3,325 (2,266)-- NL........... NC............. Unable to
coeruleoalba). Northern GOM determine.
stock.
Pantropical spotted dolphin Pelagic........ 34,067 NL........... NC............. Unable to
(Stenella attenuata). (29,311)--Nort determine.
hern GOM stock.
Atlantic spotted dolphin Coastal and Unknown NL........... NC............. Unable to
(Stenella frontalis). pelagic. (Unknown)--Nor determine.
thern GOM
stock.
Spinner dolphin (Stenella Mostly pelagic. 1,989 (1,356)-- NL........... NC............. Unable to
longirostris). Northern GOM determine.
stock.
Clymene dolphin (Stenella Pelagic........ 6,575 (4,901)-- NL........... NC............. Unable to
clymene). Northern GOM determine.
stock.
----------------------------------------------------------------------------------------------------------------
Sirenians
----------------------------------------------------------------------------------------------------------------
West Indian (Florida) manatee Coastal, 3,802--U.S. EN........... D.............. Increasing or
(Trichechus manatus rivers, and stock. stable
latrostris). estuaries. throughout
much of
Florida.
----------------------------------------------------------------------------------------------------------------
NA = Not available or not assessed.
\1\ U.S. Endangered Species Act: EN = Endangered, T = Threatened, DL = Delisted, NL = Not listed.
\2\ U.S. Marine Mammal Protection Act: D = Depleted, S = Strategic, NC = Not Classified.
\3\ NMFS Stock Assessment Reports.
\4\ USFWS Stock Assessment Reports.
Refer to sections 3 and 4 of USGS's application for detailed
information regarding the abundance and distribution, population
status, and life history and behavior of these other marine mammal
species and their occurrence in the proposed project area. The
application also presents how USGS calculated the estimated densities
for the marine mammals in the proposed survey area. NMFS has reviewed
these data and determined them to be the best available scientific
information for the purposes of the proposed IHA.
Potential Effects on Marine Mammals
Acoustic stimuli generated by the operation of the airguns, which
introduce sound into the marine environment, may have the potential to
cause Level B harassment of marine mammals in the proposed survey area.
The effects of sounds from airgun operations might include one or more
of the following: Tolerance, masking of natural sounds, behavioral
disturbance, temporary or permanent hearing impairment, or non-auditory
physical or physiological effects (Richardson et al., 1995; Gordon et
al., 2004; Nowacek et al., 2007; Southall et al., 2007). Permanent
hearing impairment, in the unlikely event that it occurred, would
constitute injury, but temporary threshold shift (TTS) is not an injury
(Southall et al., 2007). Although the possibility cannot be entirely
excluded, it is unlikely that the proposed project would result in any
cases of temporary or permanent hearing impairment, or any significant
non-auditory physical or physiological effects. Based on the available
data and studies described here, some behavioral disturbance is
expected. A more comprehensive review of these issues can be found in
the ``Programmatic Environmental Impact Statement/Overseas
Environmental Impact Statement prepared for Marine Seismic Research
that is funded by the National Science Foundation and conducted by the
U.S. Geological Survey'' (NSF/USGS, 2011).
Tolerance
Richardson et al. (1995) defines tolerance as the occurrence of
marine mammals in areas where they are exposed to human activities or
man-made noise. In many cases, tolerance develops by the animal
habituating to the stimulus (i.e., the gradual waning of responses to a
repeated or ongoing stimulus) (Richardson, et al., 1995; Thorpe, 1963),
but because of ecological or physiological requirements, many marine
animals may need to remain in
[[Page 11828]]
areas where they are exposed to chronic stimuli (Richardson, et al.,
1995).
Numerous studies have shown that pulsed sounds from airguns are
often readily detectable in the water at distances of many kilometers.
Several studies have shown that marine mammals at distances more than a
few kilometers from operating seismic vessels often show no apparent
response. That is often true even in cases when the pulsed sounds must
be readily audible to the animals based on measured received levels and
the hearing sensitivity of the marine mammal group. Although various
baleen whales and toothed whales, and (less frequently) pinnipeds have
been shown to react behaviorally to airgun pulses under some
conditions, at other times marine mammals of all three types have shown
no overt reactions. The relative responsiveness of baleen and toothed
whales are quite variable.
Masking
The term masking refers to the inability of a subject to recognize
the occurrence of an acoustic stimulus as a result of the interference
of another acoustic stimulus (Clark et al., 2009). Introduced
underwater sound may, through masking, reduce the effective
communication distance of a marine mammal species if the frequency of
the source is close to that used as a signal by the marine mammal, and
if the anthropogenic sound is present for a significant fraction of the
time (Richardson et al., 1995).
Masking effects of pulsed sounds (even from large arrays of
airguns) on marine mammal calls and other natural sounds are expected
to be limited. Because of the intermittent nature and low duty cycle of
seismic airgun pulses, animals can emit and receive sounds in the
relatively quiet intervals between pulses. However, in some situations,
reverberation occurs for much or the entire interval between pulses
(e.g., Simard et al., 2005; Clark and Gagnon, 2006) which could mask
calls. Some baleen and toothed whales are known to continue calling in
the presence of seismic pulses, and their calls can usually be heard
between the seismic pulses (e.g., Richardson et al., 1986; McDonald et
al., 1995; Greene et al., 1999; Nieukirk et al., 2004; Smultea et al.,
2004; Holst et al., 2005a,b, 2006; and Dunn and Hernandez, 2009).
However, Clark and Gagnon (2006) reported that fin whales in the North
Atlantic Ocean went silent for an extended period starting soon after
the onset of a seismic survey in the area. Similarly, there has been
one report that sperm whales ceased calling when exposed to pulses from
a very distant seismic ship (Bowles et al., 1994). However, more recent
studies found that they continued calling in the presence of seismic
pulses (Madsen et al., 2002; Tyack et al., 2003; Smultea et al., 2004;
Holst et al., 2006; and Jochens et al., 2008). Dilorio and Clark (2009)
found evidence of increased calling by blue whales during operations by
a lower-energy seismic source (i.e., sparker). Dolphins and porpoises
commonly are heard calling while airguns are operating (e.g., Gordon et
al., 2004; Smultea et al., 2004; Holst et al., 2005a, b; and Potter et
al., 2007). The sounds important to small odontocetes are predominantly
at much higher frequencies than are the dominant components of airgun
sounds, thus limiting the potential for masking.
In general, NMFS expects the masking effects of seismic pulses to
be minor, given the normally intermittent nature of seismic pulses.
Behavioral Disturbance
Marine mammals may behaviorally react to sound when exposed to
anthropogenic noise. Disturbance includes a variety of effects,
including subtle to conspicuous changes in behavior, movement, and
displacement. Reactions to sound, if any, depend on species, state of
maturity, experience, current activity, reproductive state, time of
day, and many other factors (Richardson et al., 1995; Wartzok et al.,
2004; Southall et al., 2007; Weilgart, 2007). 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 noise sources are located; and/or
flight responses. If a marine mammal does react briefly to an
underwater sound by changing its behavior or moving a small distance,
the impacts of the change are unlikely to be significant to the
individual, let alone the stock or population. However, if a sound
source displaces marine mammals from an important feeding or breeding
area for a prolonged period, impacts on individuals and populations
could be significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007).
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 could be expected to be biologically significant if the
change affects growth, survival, and/or reproduction. Some of these
significant behavioral modifications include:
Change in diving/surfacing patterns (such as those thought
to be causing beaked whale stranding due to 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) and is also difficult to predict (Richardson et
al., 1995; Southall et al., 2007). Given the many uncertainties in
predicting the quantity and types of impacts of noise on marine
mammals, it is common practice to estimate how many mammals would be
present within a particular distance of industrial activities and/or
exposed to a particular level of sound. In most cases, this approach
likely overestimates the numbers of marine mammals that would be
affected in some biologically-important manner.
Baleen Whales--Baleen whales generally tend to avoid operating
airguns, but avoidance radii are quite variable (reviewed in Richardson
et al., 1995; Gordon et al., 2004). 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 longer distances. However,
baleen whales exposed to strong noise pulses from airguns often react
by deviating from their normal migration route and/or interrupting
their feeding and moving away. In the cases of migrating gray and
bowhead whales, the observed changes in behavior appeared to be of
little or no biological consequence to the animals (Richardson, et al.,
1995). They simply avoided the sound source by displacing their
migration route to varying degrees, but within the natural boundaries
of the migration corridors.
Studies of gray, bowhead, and humpback whales have shown that
seismic pulses with received levels of 160 to 170 dB re 1 [mu]Pa (rms)
seem to cause obvious avoidance behavior in a substantial fraction of
the animals exposed (Malme et al., 1986, 1988; Richardson et al.,
1995). In many areas, seismic pulses from large arrays of airguns
diminish to those levels at distances ranging from 4 to 15 km (2.2 to
8.1 nmi) from the source. A
[[Page 11829]]
substantial proportion of the baleen whales within those distances may
show avoidance or other strong behavioral reactions to the airgun
array. Subtle behavioral changes sometimes become evident at somewhat
lower received levels, and studies have shown that some species of
baleen whales, notably bowhead, gray, and humpback whales, at times,
show strong avoidance at received levels lower than 160 to 170 dB re 1
[mu]Pa (rms).
Researchers have studied the responses of humpback whales to
seismic surveys during migration, feeding during the summer months,
breeding while offshore from Angola, and wintering offshore from
Brazil. McCauley et al. (1998, 2000a) studied the responses of humpback
whales off western Australia to a full-scale seismic survey with a 16
airgun array (2,678 in\3\) and to a single airgun (20 in\3\) with
source level of 227 dB re 1 [micro]Pa (p-p). In the 1998 study, they
documented that avoidance reactions began at 5 to 8 km (2.7 to 4.3 nmi)
from the array, and that those reactions kept most pods approximately 3
to 4 km (1.6 to 2.2 nmi) from the operating seismic boat. In the 2000
study, they noted localized displacement during migration of 4 to 5 km
(2.2 to 2.7 nmi) by traveling pods and 7 to 12 km (3.8 to 6.5 nmi) by
more sensitive resting pods of cow-calf pairs. Avoidance distances with
respect to the single airgun were smaller but consistent with the
results from the full array in terms of the received sound levels. The
mean received level for initial avoidance of an approaching airgun was
140 dB re 1 [mu]Pa (rms) for humpback pods containing females, and at
the mean closest point of approach distance the received level was 143
dB re 1 [mu]Pa (rms). The initial avoidance response generally occurred
at distances of 5 to 8 km (2.7 to 4.3 nmi) from the airgun array and 2
km (1.1 nmi) from the single airgun. However, some individual humpback
whales, especially males, approached within distances of 100 to 400 m
(328 to 1,312 ft), where the maximum received level was 179 dB re 1
[mu]Pa (rms).
Data collected by observers during several seismic surveys in the
Northwest Atlantic showed that sighting rates of humpback whales were
significantly greater during non-seismic periods compared with periods
when a full array was operating (Moulton and Holst, 2010). In addition,
humpback whales were more likely to swim away and less likely to swim
towards a vessel during seismic vs. non-seismic periods (Moulton and
Holst, 2010).
Humpback whales on their summer feeding grounds in southeast Alaska
did not exhibit persistent avoidance when exposed to seismic pulses
from a 1.64-L (100 in\3\) airgun (Malme et al., 1985). Some humpbacks
seemed ``startled'' at received levels of 150 to 169 dB re 1 [mu]Pa.
Malme et al. (1985) concluded that there was no clear evidence of
avoidance, despite the possibility of subtle effects, at received
levels up to 172 dB re 1 [mu]Pa (rms). However, Moulton and Holst
(2010) reported that humpback whales monitored during seismic surveys
in the Northwest Atlantic had lower sighting rates and were most often
seen swimming away from the vessel during seismic periods compared with
periods when airguns were silent.
Studies have suggested that South Atlantic humpback whales
wintering off Brazil may be displaced or even strand upon exposure to
seismic surveys (Engel et al., 2004). The evidence for this was
circumstantial and subject to alternative explanations (IAGC, 2004).
Also, the evidence was not consistent with subsequent results from the
same area of Brazil (Parente et al., 2006), or with direct studies of
humpbacks exposed to seismic surveys in other areas and seasons. After
allowance for data from subsequent years, there was ``no observable
direct correlation'' between strandings and seismic surveys (IWC, 2007:
236).
Reactions of migrating and feeding (but not wintering) gray whales
to seismic surveys have been studied. Malme et al. (1986, 1988) studied
the responses of feeding eastern Pacific 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 percent of
feeding gray whales stopped feeding at an average received pressure
level of 173 dB re 1 [mu]Pa on an (approximate) rms basis, and that 10
percent of feeding whales interrupted feeding at received levels of 163
dB re 1 [micro]Pa (rms). Those findings were generally consistent with
the results of experiments conducted on larger numbers of gray whales
that were migrating along the California coast (Malme et al., 1984;
Malme and Miles, 1985), and western Pacific gray whales feeding off
Sakhalin Island, Russia (Wursig et al., 1999; Gailey et al., 2007;
Johnson et al., 2007; Yazvenko et al., 2007a, b), along with data on
gray whales off British Columbia (Bain and Williams, 2006).
Various species of Balaenoptera (blue, sei, fin, and minke whales)
have occasionally been seen in areas ensonified by airgun pulses
(Stone, 2003; MacLean and Haley, 2004; Stone and Tasker, 2006), and
calls from blue and fin whales have been localized in areas with airgun
operations (e.g., McDonald et al., 1995; Dunn and Hernandez, 2009;
Castellote et al., 2010). Sightings by observers on seismic vessels off
the United Kingdom from 1997 to 2000 suggest that, during times of good
sightability, sighting rates for mysticetes (mainly fin and sei whales)
were similar when large arrays of airguns were shooting vs. silent
(Stone, 2003; Stone and Tasker, 2006). However, these whales tended to
exhibit localized avoidance, remaining significantly further (on
average) from the airgun array during seismic operations compared with
non-seismic periods (Stone and Tasker, 2006). Castellote et al. (2010)
reported that singing fin whales in the Mediterranean moved away from
an operating airgun array.
Ship-based monitoring studies of baleen whales (including blue,
fin, sei, minke, and humpback whales) in the Northwest Atlantic found
that overall, this group had lower sighting rates during seismic vs.
non-seismic periods (Moulton and Holst, 2010). Baleen whales as a group
were also seen significantly farther from the vessel during seismic
compared with non-seismic periods, and they were more often seen to be
swimming away from the operating seismic vessel (Moulton and Holst,
2010). Blue and minke whales were initially sighted significantly
farther from the vessel during seismic operations compared to non-
seismic periods; the same trend was observed for fin whales (Moulton
and Holst, 2010). Minke whales were most often observed to be swimming
away from the vessel when seismic operations were underway (Moulton and
Holst, 2010).
Data on short-term reactions by cetaceans to impulsive noises are
not necessarily indicative of long-term or biologically significant
effects. It is not known whether impulsive sounds affect reproductive
rate or distribution and habitat use in subsequent days or years.
However, gray whales have continued to migrate annually along the west
coast of North America with substantial increases in the population
over recent years, despite intermittent seismic exploration (and much
ship traffic) in that area for decades (Appendix A in Malme et al.,
1984; Richardson et al., 1995; Allen and Angliss, 2010). The western
Pacific gray whale population did not seem affected by a seismic survey
in its feeding ground during a previous year (Johnson et al., 2007).
Similarly, bowhead whales have continued to travel to the eastern
Beaufort Sea each summer, and their
[[Page 11830]]
numbers have increased notably, despite seismic exploration in their
summer and autumn range for many years (Richardson et al., 1987; Allen
and Angliss, 2010). The history of coexistence between seismic surveys
and baleen whales suggests that brief exposures to sound pulses from
any single seismic survey are unlikely to result in prolonged effects.
Toothed Whales--Little systematic information is available about
reactions of toothed whales to noise pulses. Few studies similar to the
more extensive baleen whale/seismic pulse work summarized above have
been reported for toothed whales. However, there are recent systematic
studies on sperm whales (e.g., Gordon et al., 2006; Madsen et al.,
2006; Winsor and Mate, 2006; Jochens et al., 2008; Miller et al.,
2009). 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;
Bain and Williams, 2006; Holst et al., 2006; Stone and Tasker, 2006;
Potter et al., 2007; Hauser et al., 2008; Holst and Smultea, 2008;
Weir, 2008; Barkaszi et al., 2009; Richardson et al., 2009; Moulton and
Holst, 2010).
Seismic operators and PSOs on seismic vessels regularly see
dolphins and other small toothed whales near operating airgun arrays,
but in general there is a tendency for most delphinids to show some
avoidance of operating seismic vessels (e.g., Goold, 1996a,b,c;
Calambokidis and Osmek, 1998; Stone, 2003; Moulton and Miller, 2005;
Holst et al., 2006; Stone and Tasker, 2006; Weir, 2008; Richardson et
al., 2009; Barkaszi et al., 2009; Moulton and Holst, 2010). 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 (e.g., Moulton and Miller, 2005). Nonetheless, small
toothed whales more often tend to head away, or to maintain a somewhat
greater distance from the vessel, when a large array of airguns is
operating than when it is silent (e.g., Stone and Tasker, 2006; Weir,
2008; Barry et al., 2010; Moulton and Holst, 2010). In most cases, the
avoidance radii for delphinids appear to be small, on the order of one
km or less, and some individuals show no apparent avoidance.
Captive bottlenose dolphins and beluga whales exhibited changes in
behavior when exposed to strong pulsed sounds similar in duration to
those typically used in seismic surveys (Finneran et al., 2000, 2002,
2005). However, the animals tolerated high received levels of sound
before exhibiting aversive behaviors.
Most studies of sperm whales exposed to airgun sounds indicate that
the sperm whale shows considerable tolerance of airgun pulses (e.g.,
Stone, 2003; Moulton et al., 2005, 2006a; Stone and Tasker, 2006; Weir,
2008). In most cases the whales do not show strong avoidance, and they
continue to call. However, controlled exposure experiments in the Gulf
of Mexico indicate that foraging behavior was altered upon exposure to
airgun sound (Jochens et al., 2008; Miller et al., 2009; Tyack, 2009).
There are almost no specific data on the behavioral reactions of
beaked whales to seismic surveys. However, some northern bottlenose
whales (Hyperoodon ampullatus) remained in the general area and
continued to produce high-frequency clicks when exposed to sound pulses
from distant seismic surveys (Gosselin and Lawson, 2004; Laurinolli and
Cochrane, 2005; Simard et al., 2005). Most beaked whales tend to avoid
approaching vessels of other types (e.g., Wursig et al., 1998). They
may also dive for an extended period when approached by a vessel (e.g.,
Kasuya, 1986), although it is uncertain how much longer such dives may
be as compared to dives by undisturbed beaked whales, which also are
often quite long (Baird et al., 2006; Tyack et al., 2006). Based on a
single observation, Aguilar-Soto et al. (2006) suggested that foraging
efficiency of Cuvier's beaked whales may be reduced by close approach
of vessels. In any event, it is likely that most beaked whales would
also show strong avoidance of an approaching seismic vessel, although
this has not been documented explicitly. In fact, Moulton and Holst
(2010) reported 15 sightings of beaked whales during seismic studies in
the Northwest Atlantic; seven of those sightings were made at times
when at least one airgun was operating. There was little evidence to
indicate that beaked whale behavior was affected by airgun operations;
sighting rates and distances were similar during seismic and non-
seismic periods (Moulton and Holst, 2010).
There are increasing indications that some beaked whales tend to
strand when naval exercises involving mid-frequency sonar operation are
ongoing nearby (e.g., Simmonds and Lopez-Jurado, 1991; Frantzis, 1998;
NOAA and USN, 2001; Jepson et al., 2003; Hildebrand, 2005; Barlow and
Gisiner, 2006; see also the ``Stranding and Mortality'' section in this
notice). These strandings are apparently a disturbance response,
although auditory or other injuries or other physiological effects may
also be involved. Whether beaked whales would ever react similarly to
seismic surveys is unknown. Seismic survey sounds are quite different
from those of the sonar in operation during the above-cited incidents.
Odontocete reactions to large arrays of airguns are variable and,
at least for delphinids and Dall's porpoises, seem to be confined to a
smaller radius than has been observed for the more responsive of some
mysticetes. However, other data suggest that some odontocete species,
including harbor porpoises, may be more responsive than might be
expected given their poor low-frequency hearing. Reactions at longer
distances may be particularly likely when sound propagation conditions
are conducive to transmission of the higher frequency components of
airgun sound to the animals' location (DeRuiter et al., 2006; Goold and
Coates, 2006; Tyack et al., 2006; Potter et al., 2007).
Hearing Impairment and Other Physical Effects
Exposure to high intensity sound for a sufficient duration may
result in auditory effects such as a noise-induced threshold shift--an
increase in the auditory threshold after exposure to noise (Finneran,
Carder, Schlundt, and Ridgway, 2005). Factors that influence the amount
of threshold shift include the amplitude, duration, frequency content,
temporal pattern, and energy distribution of noise exposure. The
magnitude of hearing threshold shift normally decreases over time
following cessation of the noise exposure. The amount of threshold
shift just after exposure is called the initial threshold shift. If the
threshold shift eventually returns to zero (i.e., the threshold returns
to the pre-exposure value), it is called temporary threshold shift
(TTS) (Southall et al., 2007).
Researchers have studied TTS in certain captive odontocetes and
pinnipeds exposed to strong sounds (reviewed in Southall et al., 2007).
However, there has been no specific documentation of TTS let alone
permanent hearing damage, i.e., permanent threshold shift (PTS), in
free-ranging marine mammals exposed to sequences of airgun pulses
during realistic field conditions.
Temporary Threshold Shift--TTS is the mildest form of hearing
impairment that can occur during exposure to a strong sound (Kryter,
1985). While experiencing TTS, the hearing threshold rises and a sound
must be stronger in order to be heard. At least in terrestrial mammals,
TTS can last from minutes or hours to (in cases of strong TTS) days.
[[Page 11831]]
For sound exposures at or somewhat above the TTS threshold, hearing
sensitivity in both terrestrial and marine mammals recovers rapidly
after exposure to the noise ends. Few data on sound levels and
durations necessary to elicit mild TTS have been obtained for marine
mammals, and none of the published data concern TTS elicited by
exposure to multiple pulses of sound. Available data on TTS in marine
mammals are summarized in Southall et al. (2007). Table 1 (above)
presents the estimated distances from the Pelican's airguns at which
the received energy level (per pulse, flat-weighted) would be expected
to be greater than or equal to 180 or 190 dB re 1 [micro]Pa (rms).
To avoid the potential for injury, NMFS (1995, 2000) concluded that
cetaceans should not be exposed to pulsed underwater noise at received
levels exceeding 180 and 190 dB re 1 [mu]Pa (rms), respectively. NMFS
believes that to avoid the potential for Level A harassment, cetaceans
should not be exposed to pulsed underwater noise at received levels
exceeding 180 and 190 dB re 1 [mu]Pa (rms), respectively. The
established 180 and 190 dB (rms) criteria are not considered to be the
levels above which TTS might occur. Rather, they are the received
levels above which, in the view of a panel of bioacoustics specialists
convened by NMFS before TTS measurements for marine mammals started to
become available, one could not be certain that there would be no
injurious effects, auditory or otherwise, to marine mammals.
For toothed whales, researchers have derived TTS information for
odontocetes from studies on the bottlenose dolphin and beluga. The
experiments show that exposure to a single impulse at a received level
of 207 kPa (or 30 psi, p-p), which is equivalent to 228 dB re 1 Pa (p-
p), resulted in a 7 and 6 dB TTS in the beluga whale at 0.4 and 30 kHz,
respectively. Thresholds returned to within 2 dB of the pre-exposure
level within 4 minutes of the exposure (Finneran et al., 2002). For the
one harbor porpoise tested, the received level of airgun sound that
elicited onset of TTS was lower (Lucke et al., 2009). If these results
from a single animal are representative, it is inappropriate to assume
that onset of TTS occurs at similar received levels in all odontocetes
(cf. Southall et al., 2007). Some cetaceans apparently can incur TTS at
considerably lower sound exposures than are necessary to elicit TTS in
the beluga or bottlenose dolphin.
For baleen whales, there are no data, direct or indirect, on levels
or properties of sound that are required to induce TTS. The frequencies
to which baleen whales are most sensitive are assumed to be lower than
those to which odontocetes are most sensitive, and natural background
noise levels at those low frequencies tend to be higher. As a result,
auditory thresholds of baleen whales within their frequency band of
best hearing are believed to be higher (less sensitive) than are those
of odontocetes at their best frequencies (Clark and Ellison, 2004).
From this, it is suspected that received levels causing TTS onset may
also be higher in baleen whales than those of odontocetes (Southall et
al., 2007).
Permanent Threshold Shift--When PTS occurs, there is physical
damage to the sound receptors in the ear. In severe cases, there can be
total or partial deafness, whereas in other cases, the animal has an
impaired ability to hear sounds in specific frequency ranges (Kryter,
1985). There is no specific evidence that exposure to pulses of airgun
sound can cause PTS in any marine mammal, even with large arrays of
airguns. However, given the possibility that mammals close to an airgun
array might incur at least mild TTS, there has been further speculation
about the possibility that some individuals occurring very close to
airguns might incur PTS (e.g., Richardson et al., 1995, p. 372ff;
Gedamke et al., 2008). Single or occasional occurrences of mild TTS are
not indicative of permanent auditory damage, but repeated or (in some
cases) single exposures to a level well above that causing TTS onset
might elicit PTS.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals but are assumed to be similar to those in humans and
other terrestrial mammals (Southall et al., 2007). PTS might occur at a
received sound level at least several dBs above that inducing mild TTS
if the animal were exposed to strong sound pulses with rapid rise
times. Based on data from terrestrial mammals, a precautionary
assumption is that the PTS threshold for impulse sounds (such as airgun
pulses as received close to the source) is at least 6 dB higher than
the TTS threshold on a peak-pressure basis, and probably greater than 6
dB (Southall et al., 2007).
Given the higher level of sound necessary to cause PTS as compared
with TTS, it is considerably less likely that PTS would occur. Baleen
whales generally avoid the immediate area around operating seismic
vessels, as do some other marine mammals.
Stranding and Mortality--When a living or dead marine mammal swims
or floats onto shore and becomes ``beached'' or incapable of returning
to sea, the event is termed a ``stranding'' (Geraci et al., 1999;
Perrin and Geraci, 2002; Geraci and Lounsbury, 2005; NMFS, 2007). The
legal definition for a stranding under the MMPA is that ``(A) a marine
mammal is dead and is (i) on a beach or shore of the United States; or
(ii) in waters under the jurisdiction of the United States (including
any navigable waters); or (B) a marine mammal is alive and is (i) on a
beach or shore of the United States and is unable to return to the
water; (ii) on a beach or shore of the United States and, although able
to return to the water is in need of apparent medical attention; or
(iii) in the waters under the jurisdiction of the United States
(including any navigable waters), but is unable to return to its
natural habitat under its own power or without assistance.''
Marine mammals are known to strand for a variety of reasons, such
as infectious agents, biotoxicosis, starvation, fishery interaction,
ship strike, unusual oceanographic or weather events, sound exposure,
or combinations of these stressors sustained concurrently or in series.
However, the cause or causes of most strandings are unknown (Geraci et
al., 1976; Eaton, 1979; Odell et al., 1980; Best, 1982). Numerous
studies suggest that the physiology, behavior, habitat relationships,
age, or condition of cetaceans may cause them to strand or might pre-
dispose them to strand when exposed to another phenomenon. These
suggestions are consistent with the conclusions of numerous other
studies that have demonstrated that combinations of dissimilar
stressors commonly combine to kill an animal or dramatically reduce its
fitness, even though one exposure without the other does not produce
the same result (Chroussos, 2000; Creel, 2005; DeVries et al., 2003;
Fair and Becker, 2000; Foley et al., 2001; Moberg, 2000; Relyea, 2005a,
2005b; Romero, 2004; Sih et al., 2004).
Strandings Associated with Military Active Sonar--Several sources
have published lists of mass stranding events of cetaceans in an
attempt to identify relationships between those stranding events and
military active sonar (Hildebrand, 2004; IWC, 2005; Taylor et al.,
2004). For example, based on a review of stranding records between 1960
and 1995, the International Whaling Commission (2005) identified ten
mass stranding events and concluded that, out of eight stranding events
reported from the mid-1980s to the summer of 2003, seven had been
coincident with the use of mid-
[[Page 11832]]
frequency active sonar and most involved beaked whales.
Over the past 12 years, there have been five stranding events
coincident with military mid-frequency active sonar use in which
exposure to sonar is believed to have been a contributing factor to
strandings: Greece (1996); the Bahamas (2000); Madeira (2000); Canary
Islands (2002); and Spain (2006). Refer to Cox et al. (2006) for a
summary of common features shared by the strandings events in Greece
(1996), Bahamas (2000), Madeira (2000), and Canary Islands (2002); and
Fernandez et al., (2005) for an additional summary of the Canary
Islands 2002 stranding event.
Potential for Stranding from Seismic Surveys--Marine mammals close
to underwater detonations of high explosives can be killed or severely
injured, and the auditory organs are especially susceptible to injury
(Ketten et al., 1993; Ketten, 1995). However, explosives are no longer
used in marine waters for commercial seismic surveys or (with rare
exceptions) for seismic research. These methods have been replaced
entirely by airguns or related non-explosive pulse generators. Airgun
pulses are less energetic and have slower rise times, and there is no
specific evidence that they can cause serious injury, death, or
stranding even in the case of large airgun arrays. However, the
association of strandings of beaked whales with naval exercises
involving mid-frequency active sonar (non-pulse sound) and, in one
case, the co-occurrence of an L-DEO seismic survey (Malakoff, 2002; Cox
et al., 2006), has raised the possibility that beaked whales exposed to
strong ``pulsed'' sounds could also be susceptible to injury and/or
behavioral reactions that can lead to stranding (e.g., Hildebrand,
2005; Southall et al., 2007).
Specific sound-related processes that lead to strandings and
mortality are not well documented, but may include:
(1) Swimming in avoidance of a sound into shallow water;
(2) A change in behavior (such as a change in diving behavior) that
might contribute to tissue damage, gas bubble formation, hypoxia,
cardiac arrhythmia, hypertensive hemorrhage or other forms of trauma;
(3) A physiological change such as a vestibular response leading to
a behavioral change or stress-induced hemorrhagic diathesis, leading in
turn to tissue damage; and
(4) Tissue damage directly from sound exposure, such as through
acoustically-mediated bubble formation and growth or acoustic resonance
of tissues.
Some of these mechanisms are unlikely to apply in the case of impulse
sounds. However, there are indications that gas-bubble disease
(analogous to ``the bends''), induced in supersaturated tissue by a
behavioral response to acoustic exposure, could be a pathologic
mechanism for the strandings and mortality of some deep-diving
cetaceans exposed to sonar. The evidence for this remains
circumstantial and associated with exposure to naval mid-frequency
sonar, not seismic surveys (Cox et al., 2006; Southall et al., 2007).
Seismic pulses and mid-frequency sonar signals are quite different,
and some mechanisms by which sonar sounds have been hypothesized to
affect beaked whales are unlikely to apply to airgun pulses. Sounds
produced by airgun arrays are broadband impulses with most of the
energy below one kHz. Typical military mid-frequency sonar emits non-
impulse sounds at frequencies of 2 to 10 kHz, generally with a
relatively narrow bandwidth at any one time. A further difference
between seismic surveys and naval exercises is that naval exercises can
involve sound sources on more than one vessel. Thus, it is not
appropriate to expect that the same to marine mammals will result from
military sonar and seismic surveys. However, evidence that sonar
signals can, in special circumstances, lead (at least indirectly) to
physical damage and mortality (e.g., Balcomb and Claridge, 2001; NOAA
and USN, 2001; Jepson et al., 2003; Fern[aacute]ndez et al., 2004,
2005; Hildebrand 2005; Cox et al., 2006) suggests that caution is
warranted when dealing with exposure of marine mammals to any high-
intensity sound.
There is no conclusive evidence of cetacean strandings or deaths at
sea as a result of exposure to seismic surveys, but a few cases of
strandings in the general area where a seismic survey was ongoing have
led to speculation concerning a possible link between seismic surveys
and strandings. Suggestions that there was a link between seismic
surveys and strandings of humpback whales in Brazil (Engel et al.,
2004) were not well founded (IAGC, 2004; IWC, 2007). In September,
2002, there was a stranding of two Cuvier's beaked whales in the Gulf
of California, Mexico, when the L-DEO vessel R/V Maurice Ewing was
operating a 20 airgun (8,490 in\3\) array in the general area. The link
between the stranding and the seismic surveys was inconclusive and not
based on any physical evidence (Hogarth, 2002; Yoder, 2002).
Nonetheless, the Gulf of California incident plus the beaked whale
strandings near naval exercises involving use of mid-frequency sonar
suggests a need for caution in conducting seismic surveys in areas
occupied by beaked whales until more is known about effects of seismic
surveys on those species (Hildebrand, 2005). No injuries of beaked
whales are anticipated during the proposed study because of:
(1) The high likelihood that any beaked whales nearby would avoid
the approaching vessel before being exposed to high sound levels, and
(2) Differences between the sound sources operated by L-DEO and
those involved in the naval exercises associated with strandings.
Non-auditory Physiological Effects--Non-auditory physiological
effects or injuries that theoretically might occur in marine mammals
exposed to strong underwater sound include stress, neurological
effects, bubble formation, resonance, and other types of organ or
tissue damage (Cox et al., 2006; Southall et al., 2007). Studies
examining such effects are limited. However, 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 perhaps 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.
In general, very little is known about the potential for seismic
survey sounds (or other types of strong 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. Marine mammals that show
behavioral avoidance of seismic vessels, including most baleen whales,
some odontocetes, and some pinnipeds, are especially unlikely to incur
non-auditory physical effects.
Potential Effects of Other Acoustic Devices
Sub-bottom Profiler
USGS may also operate a sub-bottom profiler from the source vessel
during the proposed survey. A hull-mounted Knudsen 3.5 kHz sub-bottom
profiler may be available since the Pelican is
[[Page 11833]]
considering such an installation in the coming months. Sounds from the
sub-bottom profiler are very short pulses, occurring for 1 to 4 ms once
every second. Most of the energy in the sound pulses emitted by the
sub-bottom profiler is at 3.5 kHz, and the beam is directed downward.
The sub-bottom profiler that may be used on the Pelican has a maximum
source level of 204 dB re 1 [micro]Pa. Kremser et al. (2005) noted that
the probability of a cetacean swimming through the area of exposure
when a bottom profiler emits a pulse is small--even for a sub-bottom
profiler more powerful than that that may be on the Pelican. If the
animal was in the area, it would have to pass the transducer at close
range in order to be subjected to sound levels that could cause TTS.
Masking--Marine mammal communications will not be masked
appreciably by the sub-bottom profiler signals given the directionality
of the signal and the brief period when an individual mammal is likely
to be within its beam. Furthermore, in the case of most baleen whales,
the sub-bottom profiler signals do not overlap with the predominant
frequencies in the calls, which would avoid significant masking.
Behavioral Responses--Marine mammal behavioral reactions to other
pulsed sound sources are discussed above, and responses to the sub-
bottom profiler are likely to be similar to those for other pulsed
sources if received at the same levels. Therefore, behavioral responses
are not expected unless marine mammals are very close to the source.
Hearing Impairment and Other Physical Effects--It is unlikely that
the sub-bottom profiler produces pulse levels strong enough to cause
hearing impairment or other physical injuries even in an animal that is
(briefly) in a position near the source. The sub-bottom profiler is
usually operated simultaneously with other higher-power acoustic
sources, including airguns. Many marine mammals will move away in
response to the approaching higher-power sources or the vessel itself
before the mammals would be close enough for there to be any
possibility of effects from the less intense sounds from the sub-bottom
profiler.
Acoustic Release Signals
The acoustic release transponder used to communicate with the OBSs
uses frequencies 9 to 13 kHz. These signals will be used
intermittently. It is unlikely that the acoustic release signals would
have a significant effect on marine mammals through masking,
disturbance, or hearing impairment. Any effects likely would be
negligible given the brief exposure at presumable low levels.
The potential effects to marine mammals described in this section
of the document do not take into consideration the proposed monitoring
and mitigation measures described later in this document (see the
``Proposed Mitigation'' and ``Proposed Monitoring and Reporting''
sections) which, as noted are designed to effect the least practicable
impact on affected marine mammal species and stocks.
Vessel Movement and Collisions
Vessel movement in the vicinity of marine mammals has the potential
to result in either a behavioral response or a direct physical
interaction. Both scenarios are discussed below in this section.
Behavioral Responses to Vessel Movement--There are limited data
concerning marine mammal behavioral responses to vessel traffic and
vessel noise, and a lack of consensus among scientists with respect to
what these responses mean or whether they result in short-term or long-
term adverse effects. In those cases where there is a busy shipping
lane or where there is a large amount of vessel traffic, marine mammals
(especially low frequency specialists) may experience acoustic masking
(Hildebrand, 2005) if they are present in the area (e.g., killer whales
in Puget Sound; Foote et al., 2004; Holt et al., 2008). In cases where
vessels actively approach marine mammals (e.g., whale watching or
dolphin watching boats), scientists have documented that animals
exhibit altered behavior such as increased swimming speed, erratic
movement, and active avoidance behavior (Bursk, 1983; Acevedo, 1991;
Baker and MacGibbon, 1991; Trites and Bain, 2000; Williams et al.,
2002; Constantine et al., 2003), reduced blow interval (Ritcher et al.,
2003), disruption of normal social behaviors (Lusseau, 2003, 2006), and
the shift of behavioral activities which may increase energetic costs
(Constantine et al., 2003, 2004). A detailed review of marine mammal
reactions to ships and boats is available in Richardson et al., (1995).
For each of the marine mammal taxonomy groups, Richardson et al.,
(1995) provides the following assessment regarding reactions to vessel
traffic:
Toothed whales--``In summary, toothed whales sometimes show no
avoidance reaction to vessels, or even approach them. However,
avoidance can occur, especially in response to vessels of types used to
chase or hunt the animals. This may cause temporary displacement, but
we know of no clear evidence that toothed whales have abandoned
significant parts of their range because of vessel traffic.''
Baleen whales--``When baleen whales receive low-level sounds from
distant or stationary vessels, the sounds often seem to be ignored.
Some whales approach the sources of these sounds. When vessels approach
whales slowly and non-aggressively, whales often exhibit slow and
inconspicuous avoidance maneuvers. In response to strong or rapidly
changing vessel noise, baleen whales often interrupt their normal
behavior and swim rapidly away. Avoidance is especially strong when a
boat heads directly toward the whale.''
Behavioral responses to stimuli are complex and influenced to
varying degrees by a number of factors, such as species, behavioral
contexts, geographical regions, source characteristics (moving or
stationary, speed, direction, etc.), prior experience of the animal and
physical status of the animal. For example, studies have shown that
beluga whales' reaction varied when exposed to vessel noise and
traffic. In some cases, beluga whales exhibited rapid swimming from
ice-breaking vessels up to 80 km (43.2 nmi) away and showed changes in
surfacing, breathing, diving, and group composition in the Canadian
high Arctic where vessel traffic is rare (Finley et al., 1990). In
other cases, beluga whales were more tolerant of vessels, but responded
differentially to certain vessels and operating characteristics by
reducing their calling rates (especially older animals) in the St.
Lawrence River where vessel traffic is common (Blane and Jaakson,
1994). In Bristol Bay, Alaska, beluga whales continued to feed when
surrounded by fishing vessels and resisted dispersal even when
purposefully harassed (Fish and Vania, 1971).
In reviewing more than 25 years of whale observation data, Watkins
(1986) concluded that whale reactions to vessel traffic were ``modified
by their previous experience and current activity: habituation often
occurred rapidly, attention to other stimuli or preoccupation with
other activities sometimes overcame their interest or wariness of
stimuli.'' Watkins noticed that over the years of exposure to ships in
the Cape Cod area, minke whales changed from frequent positive interest
(e.g., approaching vessels) to generally uninterested reactions; fin
whales changed from mostly negative (e.g., avoidance) to uninterested
reactions; fin whales changed from mostly negative (e.g., avoidance) to
uninterested
[[Page 11834]]
reactions; right whales apparently continued the same variety of
responses (negative, uninterested, and positive responses) with little
change; and humpbacks dramatically changed from mixed responses that
were often negative to reactions that were often strongly positive.
Watkins (1986) summarized that ``whales near shore, even in regions
with low vessel traffic, generally have become less wary of boats and
their noises, and they have appeared to be less easily disturbed than
previously. In particular locations with intense shipping and repeated
approaches by boats (such as the whale-watching areas of Stellwagen
Bank), more and more whales had positive reactions to familiar vessels,
and they also occasionally approached other boats and yachts in the
same ways.''
Although the radiated sound from the Pelican will be audible to
marine mammals over a large distance, it is unlikely that marine
mammals will respond behaviorally (in a manner that NMFS would consider
harassment under the MMPA) to low-level distant shipping noise as the
animals in the area are likely to be habituated to such noises (Nowacek
et al., 2004). In light of these facts, NMFS does not expect the
Pelican's movements to result in Level B harassment.
Vessel Strike--Ship strikes of cetaceans can cause major wounds,
which may lead to the death of the animal. An animal at the surface
could be struck directly by a vessel, a surfacing animal could hit the
bottom of a vessel, or an animal just below the surface could be cut by
a vessel's propeller. The severity of injuries typically depends on the
size and speed of the vessel (Knowlton and Kraus, 2001; Laist et al.,
2001; Vanderlaan and Taggart, 2007).
The most vulnerable marine mammals are those that spend extended
periods of time at the surface in order to restore oxygen levels within
their tissues after deep dives (e.g., the sperm whale). In addition,
some baleen whales, such as the North Atlantic right whale, seem
generally unresponsive to vessel sound, making them more susceptible to
vessel collisions (Nowacek et al., 2004). These species are primarily
large, slow moving whales. Smaller marine mammals (e.g., bottlenose
dolphin) move quickly through the water column and are often seen
riding the bow wave of large ships. Marine mammal responses to vessels
may include avoidance and changes in dive pattern (NRC, 2003).
An examination of all known ship strikes from all shipping sources
(civilian and military) indicates vessel speed is a principal factor in
whether a vessel strike results in death (Knowlton and Kraus, 2001;
Laist et al., 2001; Jensen and Silber, 2003; Vanderlaan and Taggart,
2007). In assessing records in which vessel speed was known, Laist et
al. (2001) found a direct relationship between the occurrence of a
whale strike and the speed of the vessel involved in the collision. The
authors concluded that most deaths occurred when a vessel was traveling
in excess of 13 kts (24.1 km/hr, 14.9 mph).
USGS's proposed operation of one source vessel for the proposed
survey is relatively small in scale compared to the number of
commercial ships transiting at higher speeds in the same areas on an
annual basis. The probability of vessel and marine mammal interactions
occurring during the proposed survey is unlikely due to the Pelican's
slow operational speed, which is typically 4.5 kts (8.1 km/hr, 5 mph).
Outside of seismic operations, the Pelican's cruising speed would be
approximately 9.2 kts (17 km/hr, 10.6 mph), which is generally below
the speed at which studies have noted reported increases of marine
mammal injury or death (Laist et al., 2001).
As a final point, the Pelican has a number of other advantages for
avoiding ship strikes as compared to most commercial merchant vessels,
including the following: the Pelican's bridge offers good visibility to
visually monitor for marine mammal presence; PSOs posted during
operations scan the ocean for marine mammals and must report visual
alerts of marine mammal presence to crew; and the PSOs receive
extensive training that covers the fundamentals of visual observing for
marine mammals and information about marine mammals and their
identification at sea.
Entanglement
Entanglement can occur if wildlife becomes immobilized in survey
lines, cables, nets, or other equipment that is moving through the
water column. The proposed seismic survey would require towing
approximately a single 450 m cable streamer. This large of an array
carries the risk of entanglement for marine mammals. Wildlife,
especially slow moving individuals, such as large whales, have a low
probability of becoming entangled due to slow speed of the survey
vessel and onboard monitoring efforts. In May, 2011, there was one
recorded entanglement of an olive ridley sea turtle (Lepidochelys
olivacea) in the R/V Marcus G. Langseth's barovanes after the
conclusion of a seismic survey off Costa Rica. There have cases of
baleen whales, mostly gray whales (Heyning, 1990), becoming entangled
in fishing lines. The probability for entanglement of marine mammals is
considered not significant because of the vessel speed and the
monitoring efforts onboard the survey vessel.
The potential effects to marine mammals described in this section
of the document do not take into consideration the proposed monitoring
and mitigation measures described later in this document (see the
``Proposed Mitigation'' and ``Proposed Monitoring and Reporting''
sections) which, as noted are designed to effect the least practicable
impact on affected marine mammal species and stocks.
Anticipated Effects on Marine Mammal Habitat
The proposed seismic survey is not anticipated to have any
permanent impact on habitats used by the marine mammals in the proposed
survey area, including the food sources they use (i.e. fish and
invertebrates). Additionally, no physical damage to any habitat is
anticipated as a result of conducting the proposed seismic survey.
While it is anticipated that the specified activity may result in
marine mammals avoiding certain areas due to temporary ensonification,
this impact to habitat is temporary and was considered in further
detail earlier in this document, as behavioral modification. The main
impact associated with the proposed activity will be temporarily
elevated noise levels and the associated direct effects on marine
mammals in any particular area of the approximately 445.4 km\2\
proposed project area, previously discussed in this notice. The next
section discusses the potential impacts of anthropogenic sound sources
on common marine mammal prey in the proposed survey area (i.e., fish
and invertebrates).
Anticipated Effects on Fish
One reason for the adoption of airguns as the standard energy
source for marine seismic surveys is that, unlike explosives, they have
not been associated with large-scale fish kills. However, existing
information on the impacts of seismic surveys on marine fish and
invertebrate populations is limited. There are three types of potential
effects of exposure to seismic surveys: (1) Pathological, (2)
physiological, and (3) behavioral. Pathological effects involve lethal
and temporary or permanent sub-lethal injury. Physiological effects
involve temporary and permanent primary and secondary stress responses,
such as changes in levels of enzymes and proteins. Behavioral effects
refer to temporary and (if they occur) permanent
[[Page 11835]]
changes in exhibited behavior (e.g., startle and avoidance behavior).
The three categories are interrelated in complex ways. For example, it
is possible that certain physiological and behavioral changes could
potentially lead to an ultimate pathological effect on individuals
(i.e., mortality).
The specific received sound levels at which permanent adverse
effects to fish potentially could occur are little studied and largely
unknown. Furthermore, the available information on the impacts of
seismic surveys on marine fish is from studies of individuals or
portions of a population; there have been no studies at the population
scale. The studies of individual fish have often been on caged fish
that were exposed to airgun pulses in situations not representative of
an actual seismic survey. Thus, available information provides limited
insight on possible real-world effects at the ocean or population
scale. This makes drawing conclusions about impacts on fish problematic
because, ultimately, the most important issues concern effects on
marine fish populations, their viability, and their availability to
fisheries.
Hastings and Popper (2005), Popper (2009), and Popper and Hastings
(2009a,b) provided recent critical reviews of the known effects of
sound on fish. The following sections provide a general synopsis of the
available information on the effects of exposure to seismic and other
anthropogenic sound as relevant to fish. The information comprises
results from scientific studies of varying degrees of rigor plus some
anecdotal information. Some of the data sources may have serious
shortcomings in methods, analysis, interpretation, and reproducibility
that must be considered when interpreting their results (see Hastings
and Popper, 2005). Potential adverse effects of the program's sound
sources on marine fish are noted.
Pathological Effects--The potential for pathological damage to
hearing structures in fish depends on the energy level of the received
sound and the physiology and hearing capability of the species in
question. For a given sound to result in hearing loss, the sound must
exceed, by some substantial amount, the hearing threshold of the fish
for that sound (Popper, 2005). The consequences of temporary or
permanent hearing loss in individual fish on a fish population are
unknown; however, they likely depend on the number of individuals
affected and whether critical behaviors involving sound (e.g., predator
avoidance, prey capture, orientation and navigation, reproduction,
etc.) are adversely affected.
Little is known about the mechanisms and characteristics of damage
to fish that may be inflicted by exposure to seismic survey sounds. Few
data have been presented in the peer-reviewed scientific literature. As
far as USGS and NMFS know, there are only two papers with proper
experimental methods, controls, and careful pathological investigation
implicating sounds produced by actual seismic survey airguns in causing
adverse anatomical effects. One such study indicated anatomical damage,
and the second indicated TTS in fish hearing. The anatomical case is
McCauley et al. (2003), who found that exposure to airgun sound caused
observable anatomical damage to the auditory maculae of pink snapper
(Pagrus auratus). This damage in the ears had not been repaired in fish
sacrificed and examined almost two months after exposure. On the other
hand, Popper et al. (2005) documented only TTS (as determined by
auditory brainstem response) in two of three fish species from the
Mackenzie River Delta. This study found that broad whitefish (Coregonus
nasus) exposed to five airgun shots were not significantly different
from those of controls. During both studies, the repetitive exposure to
sound was greater than would have occurred during a typical seismic
survey. However, the substantial low-frequency energy produced by the
airguns (less than 400 Hz in the study by McCauley et al. [2003] and
less than approximately 200 Hz in Popper et al. [2005]) likely did not
propagate to the fish because the water in the study areas was very
shallow (approximately nine m in the former case and less than two m in
the latter). Water depth sets a lower limit on the lowest sound
frequency that will propagate (the ``cutoff frequency'') at about one-
quarter wavelength (Urick, 1983; Rogers and Cox, 1988).
Wardle et al. (2001) suggested that in water, acute injury and
death of organisms exposed to seismic energy depends primarily on two
features of the sound source: (1) the received peak pressure, and (2)
the time required for the pressure to rise and decay. Generally, as
received pressure increases, the period for the pressure to rise and
decay decreases, and the chance of acute pathological effects
increases. According to Buchanan et al. (2004), for the types of
seismic airguns and arrays involved with the proposed program, the
pathological (mortality) zone for fish would be expected to be within a
few meters of the seismic source. Numerous other studies provide
examples of no fish mortality upon exposure to seismic sources (Falk
and Lawrence, 1973; Holliday et al., 1987; La Bella et al., 1996;
Santulli et al., 1999; McCauley et al., 2000a,b, 2003; Bjarti, 2002;
Thomsen, 2002; Hassel et al., 2003; Popper et al., 2005; Boeger et al.,
2006).
An experiment of the effects of a single 700 in\3\ airgun was
conducted in Lake Meade, Nevada (USGS, 1999). The data were used in an
Environmental Assessment of the effects of a marine reflection survey
of the Lake Meade fault system by the National Park Service (Paulson et
al., 1993, in USGS, 1999). The airgun was suspended 3.5 m (11.5 ft)
above a school of threadfin shad in Lake Meade and was fired three
successive times at a 30 second interval. Neither surface inspection
nor diver observations of the water column and bottom found any dead
fish.
For a proposed seismic survey in Southern California, USGS (1999)
conducted a review of the literature on the effects of airguns on fish
and fisheries. They reported a 1991 study of the Bay Area Fault system
from the continental shelf to the Sacramento River, using a 10 airgun
(5,828 in\3\) array. Brezzina and Associates were hired by USGS to
monitor the effects of the surveys and concluded that airgun operations
were not responsible for the death of any of the fish carcasses
observed. They also concluded that the airgun profiling did not appear
to alter the feeding behavior of sea lions, seals, or pelicans observed
feeding during the seismic surveys.
Some studies have reported, some equivocally, that mortality of
fish, fish eggs, or larvae can occur close to seismic sources
(Kostyuchenko, 1973; Dalen and Knutsen, 1986; Booman et al., 1996;
Dalen et al., 1996). Some of the reports claimed seismic effects from
treatments quite different from actual seismic survey sounds or even
reasonable surrogates. However, Payne et al. (2009) reported no
statistical differences in mortality/morbidity between control and
exposed groups of capelin eggs or monkfish larvae. Saetre and Ona
(1996) applied a `worst-case scenario' mathematical model to
investigate the effects of seismic energy on fish eggs and larvae. They
concluded that mortality rates caused by exposure to seismic surveys
are so low, as compared to natural mortality rates, that the impact of
seismic surveying on recruitment to a fish stock must be regarded as
insignificant.
Physiological Effects--Physiological effects refer to cellular and/
or biochemical responses of fish to acoustic stress. Such stress
potentially
[[Page 11836]]
could affect fish populations by increasing mortality or reducing
reproductive success. Primary and secondary stress responses of fish
after exposure to seismic survey sound appear to be temporary in all
studies done to date (Sverdrup et al., 1994; Santulli et al., 1999;
McCauley et al., 2000a,b). The periods necessary for the biochemical
changes to return to normal are variable and depend on numerous aspects
of the biology of the species and of the sound stimulus.
Behavioral Effects--Behavioral effects include changes in the
distribution, migration, mating, and catchability of fish populations.
Studies investigating the possible effects of sound (including seismic
survey sound) on fish behavior have been conducted on both uncaged and
caged individuals (e.g., Chapman and Hawkins, 1969; Pearson et al.,
1992; Santulli et al., 1999; Wardle et al., 2001; Hassel et al., 2003).
Typically, in these studies fish exhibited a sharp startle response at
the onset of a sound followed by habituation and a return to normal
behavior after the sound ceased.
The Minerals Management Service (MMS, 2005) assessed the effects of
a proposed seismic survey in Cook Inlet. The seismic survey proposed
using three vessels, each towing two, four-airgun arrays ranging from
1,500 to 2,500 in\3\. MMS noted that the impact to fish populations in
the survey area and adjacent waters would likely be very low and
temporary. MMS also concluded that seismic surveys may displace the
pelagic fishes from the area temporarily when airguns are in use.
However, fishes displaced and avoiding the airgun noise are likely to
backfill the survey area in minutes to hours after cessation of seismic
testing. Fishes not dispersing from the airgun noise (e.g., demersal
species) may startle and move short distances to avoid airgun
emissions.
In general, any adverse effects on fish behavior or fisheries
attributable to seismic testing may depend on the species in question
and the nature of the fishery (season, duration, fishing method). They
may also depend on the age of the fish, its motivational state, its
size, and numerous other factors that are difficult, if not impossible,
to quantify at this point, given such limited data on effects of
airguns on fish, particularly under realistic at-sea conditions.
Anticipated Effects on Invertebrates
The existing body of information on the impacts of seismic survey
sound on marine invertebrates is very limited. However, there is some
unpublished and very limited evidence of the potential for adverse
effects on invertebrates, thereby justifying further discussion and
analysis of this issue. The three types of potential effects of
exposure to seismic surveys on marine invertebrates are pathological,
physiological, and behavioral. Based on the physical structure of their
sensory organs, marine invertebrates appear to be specialized to
respond to particle displacement components of an impinging sound field
and not to the pressure component (Popper et al., 2001).
The only information available on the impacts of seismic surveys on
marine invertebrates involves studies of individuals; there have been
no studies at the population scale. Thus, available information
provides limited insight on possible real-world effects at the regional
or ocean scale. The most important aspect of potential impacts concerns
how exposure to seismic survey sound ultimately affects invertebrate
populations and their viability, including availability to fisheries.
Literature reviews of the effects of seismic and other underwater
sound on invertebrates were provided by Moriyasu et al. (2004) and
Payne et al. (2008). The following sections provide a synopsis of
available information on the effects of exposure to seismic survey
sound on species of decapod crustaceans and cephalopods, the two
taxonomic groups of invertebrates on which most such studies have been
conducted. The available information is from studies with variable
degrees of scientific soundness and from anecdotal information. A more
detailed review of the literature on the effects of seismic survey
sound on invertebrates is provided in Appendix D of NSF/USGS's PEIS.
Pathological Effects--In water, lethal and sub-lethal injury to
organisms exposed to seismic survey sound appears to depend on at least
two features of the sound source: (1) the received peak pressure; and
(2) the time required for the pressure to rise and decay. Generally, as
received pressure increases, the period for the pressure to rise and
decay decreases, and the chance of acute pathological effects
increases. For the type of airgun array planned for the proposed
program, the pathological (mortality) zone for crustaceans and
cephalopods is expected to be within a few meters of the seismic
source, at most; however, very few specific data are available on
levels of seismic signals that might damage these animals. This premise
is based on the peak pressure and rise/decay time characteristics of
seismic airgun arrays currently in use around the world.
Some studies have suggested that seismic survey sound has a limited
pathological impact on early developmental stages of crustaceans
(Pearson et al., 1994; Christian et al., 2003; DFO, 2004). However, the
impacts appear to be either temporary or insignificant compared to what
occurs under natural conditions. Controlled field experiments on adult
crustaceans (Christian et al., 2003, 2004; DFO, 2004) and adult
cephalopods (McCauley et al., 2000a,b) exposed to seismic survey sound
have not resulted in any significant pathological impacts on the
animals. It has been suggested that exposure to commercial seismic
survey activities has injured giant squid (Guerra et al., 2004), but
the article provides little evidence to support this claim. Tenera
Environmental (2011b) reported that Norris and Mohl (1983, summarized
in Mariyasu et al., 2004) observed lethal effects in squid (Loligo
vulgaris) at levels of 246 to 252 dB after 3 to 11 minutes.
Andre et al. (2011) exposed four species of cephalopods (Loligo
vulgaris, Sepia officinalis, Octopus vulgaris, and Ilex coindetii),
primarily cuttlefish, to two hours of continuous 50 to 400 Hz
sinusoidal wave sweeps at 157+/-5 dB re 1 [micro]Pa while captive in
relatively small tanks. They reported morphological and ultrastructural
evidence of massive acoustic trauma (i.e., permanent and substantial
alterations [lesions] of statocyst sensory hair cells) to the exposed
animals that increased in severity with time, suggesting that
cephalopods are particularly sensitive to low frequency sound. The
received SPL was reported as 157+/-5 dB re 1 [micro]Pa, with peak
levels at 175 dB re 1 [micro]Pa. As in the McCauley et al. (2003) paper
on sensory hair cell damage in pink snapper as a result of exposure to
seismic sound, the cephalopods were subjected to higher sound levels
than they would be under natural conditions, and they were unable to
swim away from the sound source.
Physiological Effects--Physiological effects refer mainly to
biochemical responses by marine invertebrates to acoustic stress. Such
stress potentially could affect invertebrate populations by increasing
mortality or reducing reproductive success. Primary and secondary
stress responses (i.e., changes in haemolymph levels of enzymes,
proteins, etc.) of crustaceans have been noted several days or months
after exposure to seismic survey sounds (Payne et al., 2007). It was
noted however, than no behavioral impacts
[[Page 11837]]
were exhibited by crustaceans (Christian et al., 2003, 2004; DFO,
2004). The periods necessary for these biochemical changes to return to
normal are variable and depend on numerous aspects of the biology of
the species and of the sound stimulus.
Behavioral Effects--There is increasing interest in assessing the
possible direct and indirect effects of seismic and other sounds on
invertebrate behavior, particularly in relation to the consequences for
fisheries. Changes in behavior could potentially affect such aspects as
reproductive success, distribution, susceptibility to predation, and
catchability by fisheries. Studies investigating the possible
behavioral effects of exposure to seismic survey sound on crustaceans
and cephalopods have been conducted on both uncaged and caged animals.
In some cases, invertebrates exhibited startle responses (e.g., squid
in McCauley et al., 2000a,b). In other cases, no behavioral impacts
were noted (e.g., crustaceans in Christian et al., 2003, 2004; DFO
2004). There have been anecdotal reports of reduced catch rates of
shrimp shortly after exposure to seismic surveys; however, other
studies have not observed any significant changes in shrimp catch rate
(Andriguetto-Filho et al., 2005). Similarly, Parry and Gason (2006) did
not find any evidence that lobster catch rates were affected by seismic
surveys. Any adverse effects on crustacean and cephalopod behavior or
fisheries attributable to seismic survey sound depend on the species in
question and the nature of the fishery (season, duration, fishing
method).
OBS Deployment--A total of approximately 25 OBSs will be deployed
during the proposed survey. OBSs operated by the U.S. National OBS
Instrument Pool will be used during the proposed cruise. This type of
OBS has a height of approximately 1 m (3.3 ft) and a maximum diameter
of 50 cm (19.7 in). The anchor is a steel plate weighing approximately
40 kg (88.2 lb) with dimensions approximately 30 x 30 x 8 cm (11.8 x
11.8 x 3.1 in). Once an OBS is ready to be retrieved, an acoustic
release transponder interrogates the instrument at a frequency of 9 to
11 kHz, and a response is received at a frequency of 9 to 13 kHz. The
burn-wire release assembly is then activated, and the instrument is
released from the anchor to float to the surface. OBS anchors will be
left behind upon equipment recovery. Although OBS placement will
disrupt a very small area of the seafloor habitat and could disturb
invertebrates, the impacts are expected to be localized and transitory.
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 the availability of such species or
stock for taking for certain subsistence uses.
USGS reviewed the following source documents and have incorporated
a suite of appropriate mitigation measures into their project
description.
(1) Protocols used during previous NSF and USGS-funded seismic
research cruises as approved by NMFS and detailed in the recently
completed Final Programmatic Environmental Impact Statement/Overseas
Environmental Impact Statement for Marine Seismic Research Funded by
the National Science Foundation or Conducted by the U.S. Geological
Survey;
(2) Previous IHA applications and IHAs approved and authorized by
NMFS; and
(3) Recommended best practices in Richardson et al. (1995), Pierson
et al. (1998), and Weir and Dolman, (2007).
To reduce the potential for disturbance from acoustic stimuli
associated with the activities, USGS and/or its designees have proposed
to implement the following mitigation measures for marine mammals:
(1) Proposed exclusion zones around the sound source;
(2) Speed and course alterations;
(3) Shut-down procedures; and
(4) Ramp-up procedures.
Proposed Exclusion Zones--USGS use radii to designate exclusion and
buffer zones and to estimate take for marine mammals. Table 1
(presented earlier in this document) shows the distances at which one
would expect to receive three sound levels (160, 180, and 190 dB) from
the 18 airgun array and a single airgun. The 180 dB and 190 dB level
shut-down criteria are applicable to cetaceans and pinnipeds,
respectively, as specified by NMFS (2000). USGS used these levels to
establish the exclusion and buffer zones.
Received sound levels have been modeled by L-DEO for a number of
airgun configurations, including two 105 in\3\ GI airguns, in relation
to distance and direction from the airguns (see Figure 2 of the IHA
application). The model does not allow for bottom interactions, and is
most directly applicable to deep water. Based on the modeling,
estimates of the maximum distances from the GI airguns where sound
levels are predicted to be 190, 180, and 160 dB re 1 [micro]Pa (rms) in
deep water were determined (see Table 1 above).
Empirical data concerning the 190, 180, and 160 dB (rms) distances
were acquired for various airgun arrays based on measurements during
the acoustic verification studies conducted by L-DEO in the northern
GOM in 2003 (Tolstoy et al., 2004) and 2007 to 2008 (Tolstoy et al.,
2009). Results of the 36 airgun array are not relevant for the 2 GI
airguns to be used in the proposed survey. The empirical data for the
6, 10, 12, and 20 airgun arrays indicate that, for deep water, the L-
DEO model tends to overestimate the received sound levels at a given
distance (Tolstoy et al., 2004). Measurements were not made for the two
GI airgun array in deep water; however, USGS propose to use the safety
radii predicted by L-DEO's model for the proposed GI airgun operations
in deep water, although they are likely conservative given the
empirical results for the other arrays. The 180 and 190 dB (rms) radii
are shut-down criteria applicable to cetaceans and pinnipeds,
respectively, as specified by NMFS (2000); these levels were used to
establish exclusion zones. Therefore, the assumed 180 and 190 dB radii
are 70 m (229.7 ft) and 20 m (65.6 ft), respectively. If the PSO
detects a marine mammal(s) within or about to enter the appropriate
exclusion zone, the airguns will be shut-down immediately.
Speed and Course Alterations--If a marine mammal is detected
outside the exclusion zone and, based on its position and direction of
travel (relative motion), is likely to enter the exclusion zone,
changes of the vessel's speed and/or direct course will be considered
if this does not compromise operational safety. This would be done if
operationally practicable while minimizing the effect on the planned
science objectives. For marine seismic surveys towing large streamer
arrays, however, course alterations are not typically implemented due
to the vessel's limited maneuverability. After any such speed and/or
course alteration is begun, the marine mammal activities and movements
relative to the seismic vessel will be closely monitored to ensure that
the marine mammal does not approach within the exclusion zone. If the
marine mammal appears likely to enter the exclusion zone, further
mitigation actions will be taken, including further course alterations
and/or shut-down of the airgun(s). Typically, during seismic
operations, the source vessel is unable to change speed or course, and
one or more alternative
[[Page 11838]]
mitigation measures will need to be implemented.
Shut-down Procedures--USGS will shut-down the operating airgun(s)
if a marine mammal is detected outside the exclusion zone for the
airgun(s), and if the vessel's speed and/or course cannot be changed to
avoid having the animal enter the exclusion zone, the seismic source
will be shut-down before the animal is within the exclusion zone.
Likewise, if a marine mammal is already within the exclusion zone when
first detected, the seismic source will be shut down immediately.
Following a shut-down, USGS will not resume airgun activity until
the marine mammal has cleared the exclusion zone. USGS will consider
the animal to have cleared the exclusion zone if:
A PSO has visually observed the animal leave the exclusion
zone, or
A PSO has not sighted the animal within the exclusion zone
for 15 minutes for species with shorter dive durations (i.e., small
odontocetes or pinnipeds), or 30 minutes for species with longer dive
durations (i.e., mysticetes and large odontocetes, including sperm,
killer, and beaked whales).
Although power-down procedures are often standard operating
practice for seismic surveys, they are not proposed to be used during
this planned seismic survey because powering-down from two airguns to
one airgun would make only a small difference in the exclusion
zone(s)--but probably not enough to allow continued one-airgun
operations if a marine mammal came within the exclusion zone for two
airguns.
Ramp-up Procedures--Ramp-up of an airgun array provides a gradual
increase in sound levels, and involves a step-wise increase in the
number and total volume of airguns firing until the full volume of the
airgun array is achieved. The purpose of a ramp-up is to ``warn''
marine mammals in the vicinity of the airguns and to provide the time
for them to leave the area avoiding any potential injury or impairment
of their hearing abilities. USGS will follow a ramp-up procedure when
the airgun array begins operating after a specified period without
airgun operations or when a shut-down shut down has exceeded that
period. USGS proposes that, for the present cruise, this period would
be approximately 15 minutes. L-DEO and Scripps Institution of
Oceanography (SIO) has used similar periods (approximately 15 minutes)
during previous low-energy seismic surveys.
Ramp-up will begin with a single GI airgun (105 in\3\). The second
GI airgun (105 in\3\) will be added after 5 minutes. During ramp-up,
the PSOs will monitor the exclusion zone, and if marine mammals are
sighted, a shut-down will be implemented as though both GI airguns were
operational.
If the complete exclusion zone has not been visible for at least 30
minutes prior to the start of operations in either daylight or
nighttime, USGS will not commence the ramp-up. Given these provisions,
it is likely that the airgun array will not be ramped-up from a
complete shut-down at night or in thick fog, because the outer part of
the exclusion zone for that array will not be visible during those
conditions. If one airgun has operated, ramp-up to full power will be
permissible at night or in poor visibility, on the assumption that
marine mammals will be alerted to the approaching seismic vessel by the
sounds from the single airgun and could move away if they choose. A
ramp-up from a shut-down may occur at night, by only where the
exclusion zone is small enough to be visible. USGS will not initiate a
ramp-up of the airguns if a marine mammal is sighted within or near the
applicable exclusion zones during the day or close to the vessel at
night.
NMFS has carefully evaluated the applicant's proposed mitigation
measures and has considered a range of other measures in the context of
ensuring that NMFS prescribes the means of effecting the least
practicable adverse impact on the affected marine mammal species and
stocks and their habitat. NMFS's evaluation of potential measures
included consideration of the following factors in relation to one
another:
(1) The manner in which, and the degree to which, the successful
implementation of the measure is expected to minimize adverse impacts
to marine mammals;
(2) The proven or likely efficacy of the specific measure to
minimize adverse impacts as planned; and
(3) The practicability of the measure for applicant implementation.
Based on NMFS's evaluation of the applicant's proposed measures, as
well as other measures considered by NMFS or recommended by the public,
NMFS has preliminarily determined that the proposed mitigation measures
provide the means of effecting the least practicable adverse impacts on
marine mammal species or stocks and their habitat, paying particular
attention to rookeries, mating grounds, and areas of similar
significance.
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 IHAs
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 action area.
Proposed Monitoring
USGS propose to sponsor marine mammal monitoring during the
proposed project, in order to implement the proposed mitigation
measures that require real-time monitoring, and to satisfy the
anticipated monitoring requirements of the IHA. L-DEO and PG&E's
proposed ``Monitoring Plan'' is described below this section. USGS
understand that this monitoring plan will be subject to review by NMFS
and that refinements may be required. The monitoring work described
here has been planned as a self-contained project independent of any
other related monitoring projects that may be occurring simultaneously
in the same regions. USGS are prepared to discuss coordination of their
monitoring program with any related work that might be done by other
groups insofar as this is practical and desirable.
Vessel-Based Visual Monitoring
PSOs will be based aboard the seismic source vessel and will watch
for marine mammals near the vessel during daytime airgun operations and
during any ramp-ups of the airguns at night. PSOs will also watch for
marine mammals near the seismic vessel for at least 30 minutes prior to
the start of airgun operations after an extended shut-down (i.e.,
greater than approximately 15 minutes for this proposed cruise). When
feasible, PSOs will conduct observations during daytime periods when
the seismic system is not operating for comparison of sighting rates
and behavior with and without airgun operations and between acquisition
periods. Based on PSO observations, the airguns will be shut-down when
marine mammals are observed within or about to enter a designated
exclusion zone. The exclusion zone is a region in which a possibility
exists of adverse effects on animal hearing or other physical effects.
During seismic operations in the deep water of the northwestern
GOM, at least three PSOs will be based aboard the Pelican. USGS will
appoint the PSOs
[[Page 11839]]
with NMFS's concurrence. Observations will take place during ongoing
daytime operations and nighttime ramp-ups of the airguns. During the
majority of seismic operations, at least one PSO will be on duty from
observation platforms (i.e., the best available vantage point on the
source vessel) to monitor marine mammals near the seismic vessel.
PSO(s) will be on duty in shifts no longer than 4 hours in duration.
Other crew will also be instructed to assist in detecting marine
mammals and implementing mitigation requirements (if practical). Before
the start of the seismic survey, the crew will be given additional
instruction on how to do so.
The Pelican is a suitable platform for marine mammal observations
and will serve as the platform from which PSOs will watch for marine
mammals before and during seismic operations. Two locations are likely
as observation stations onboard the Pelican. When stationed on the aft
control station on the upper deck (01 level), the eye level will be
approximately 12 m (39.3 ft) above sea level, and the PSO will have an
approximately 210[deg] view aft of the vessel centered on the seismic
source location. At the bridge station, the eye level will be
approximately 13 m (42.7 ft) above sea level, and the location will
offer a full 360[deg] view around the entire vessel. During daytime,
the PSO(s) will scan the area around the vessel systematically with
reticle binoculars (e.g., 7 x 50 Fujinon), optical range-finders (to
assist with distance estimation), and the naked eye. At night, night-
vision equipment will be available. The optical range-finders are
useful in training observers to estimate distances visually, but are
generally not useful in measuring distances to animals directly.
Estimating distances is done primarily with the reticles in the
binoculars. The PSO(s) will be in wireless communication with ship's
officers on the bridge and scientists in the vessel's operations
laboratory, so they can advise promptly of the need for avoidance
maneuvers or a shut-down of the seismic source.
When marine mammals are detected within or about to enter the
designated exclusion zone, the airguns will immediately be shut-down if
necessary. The PSO(s) will continue to maintain watch to determine when
the animal(s) are outside the exclusion zone by visual confirmation.
Airgun operations will not resume until the animal is confirmed to have
left the exclusion zone, or if not observed after 15 minutes for
species with shorter dive durations (small odontocetes) or 30 minutes
for species with longer dive durations (mysticetes and large
odontocetes, including sperm, pygmy sperm, dwarf sperm, killer, and
beaked whales).
PSO Data and Documentation
PSOs will record data to estimate the numbers of marine mammals
exposed to various received sound levels and to document apparent
disturbance reactions or lack thereof. Data will be used to estimate
numbers of animals potentially ``taken'' by harassment (as defined in
the MMPA). They will also provide information needed to order a shut-
down of the airguns when a marine mammal is within or near the
exclusion zone. Observations will also be made during daytime periods
when the Pelican is underway without seismic operations (i.e.,
transits, to, from, and through the study area) to collect baseline
biological data.
When a sighting is made, the following information about the
sighting will be recorded:
1. Species, group size, age/size/sex categories (if determinable),
behavior when first sighted and after initial sighting, heading (if
consistent), bearing and distance from seismic vessel, sighting cue,
apparent reaction to the seismic source or vessel (e.g., none,
avoidance, approach, paralleling, etc.), and behavioral pace.
2. Time, location, heading, speed, activity of the vessel, sea
state, wind force, visibility, and sun glare.
The data listed under (2) will also be recorded at the start and
end of each observation watch, and during a watch whenever there is a
change in one or more of the variables.
All observations, as well as information regarding ramp-ups or
shut-downs will be recorded in a standardized format. The data accuracy
will be verified by the PSOs at sea, and preliminary reports will be
prepared during the field program and summaries forwarded to the
operating institution's shore facility weekly or more frequently.
Results from the vessel-based observations will provide the
following information:
1. The basis for real-time mitigation (airgun shut-down).
2. Information needed to estimate the number of marine mammals
potentially taken by harassment, which must be reported to NMFS.
3. Data on the occurrence, distribution, and activities of marine
mammals in the area where the seismic study is conducted.
4. Information to compare the distance and distribution of marine
mammals relative to the source vessel at times with and without seismic
activity.
5. Data on the behavior and movement patterns of marine mammals
seen at times with and without seismic activity.
USGS will submit a comprehensive report to NMFS within 90 days
after the end of the cruise. The report will describe the operations
that were conducted and sightings of marine mammals near the
operations. The report submitted to NMFS will provide full
documentation of methods, results, and interpretation pertaining to all
monitoring. The 90-day report will summarize the dates and locations of
seismic operations and all marine mammal sightings (i.e., dates, times,
locations, activities, and associated seismic survey activities). The
report will minimally include:
Summaries of monitoring effort--total hours, total
distances, and distribution of marine mammals 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 including sea state, number of PSOs,
and fog/glare;
Species composition, occurrence, and distribution of
marine mammals sightings including date, water depth, numbers, age/
size/gender, and group sizes; and analyses of the effects of seismic
operations;
Sighting rates of marine mammals during periods with and
without airgun activities (and other variables that could affect
detectability);
Initial sighting distances versus airgun activity state;
Closest point of approach versus airgun activity state;
Observed behaviors and types of movements versus airgun
activity state;
Numbers of sightings/individuals seen versus airgun
activity state; and
Distribution around the source vessel versus airgun
activity state.
The report will also include estimates of the number and nature of
exposures that could result in ``takes'' of marine mammals by
harassment or in other ways. After the report is considered final, it
will be publicly available on the NMFS Web site at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#iha.
In the unanticipated event that the specified activity clearly
causes the take of a marine mammal in a manner prohibited by this IHA,
such as an injury (Level A harassment), serious injury or mortality
(e.g., ship-strike, gear interaction, and/or entanglement), USGS will
immediately cease the specified activities and immediately report the
incident to the Chief of the Permits and Conservation Division,
[[Page 11840]]
Office of Protected Resources, NMFS at 301-427-8401 and/or by email to
[email protected] and [email protected], and the NMFS
Southeast Region Marine Mammal Stranding Network at 877-433-8299
([email protected] and [email protected]) or the Florida Marine
Mammal Stranding Hotline at 888-404-3922. The report must 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 shall not resume until NMFS is able to review the
circumstances of the prohibited take. NMFS shall work with USGS to
determine what is necessary to minimize the likelihood of further
prohibited take and ensure MMPA compliance. USGS may not resume their
activities until notified by NMFS via letter or email, or telephone.
In the event that USGS 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),
USGS will immediately report the incident to the Chief of the Permits
and Conservation Division, Office of Protected Resources, NMFS, at 301-
427-8401, and/or by email to [email protected] and
[email protected], and the NMFS Southeast Region Marine Mammal
Stranding Network (877-433-8299) and/or by email to the Southeast
Regional Stranding Coordinator ([email protected]) and Southeast
Regional Stranding Program Administrator ([email protected]). The
report must include the same information identified in the paragraph
above. Activities may continue while NMFS reviews the circumstances of
the incident. NMFS will work with USGS to determine whether
modifications in the activities are appropriate.
In the event that USGS 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 or advanced
decomposition, or scavenger damage), USGS will report the incident to
the Chief of the Permits and Conservation Division, Office of Protected
Resources, NMFS, at 301-427-8401, and/or by email to
[email protected] and [email protected], and the NMFS
Southeast Regional Marine Mammal Stranding Network (877-433-8299), and/
or by email to the Southeast Regional Stranding Coordinator
([email protected]) and Southeast Regional Stranding Program
Administrator ([email protected]), within 24 hours of discovery.
USGS will provide photographs or video footage (if available) or other
documentation of the stranded animal sighting to NMFS and the Marine
Mammal Stranding Network. Activities may continue while NMFS reviews
the circumstances of the incident.
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].
Level B harassment is anticipated and proposed to be authorized as
a result of the proposed low-energy marine seismic survey in the deep
water of the northwestern GOM. Acoustic stimuli (i.e., increased
underwater sound) generated during the operation of the seismic airgun
array are expected to result in the behavioral disturbance of some
marine mammals. There is no evidence that the planned activities could
result in injury, serious injury, or mortality for which USGS seeks the
IHA. The required mitigation and monitoring measures will minimize any
potential risk for injury, serious injury, or mortality.
The following sections describe USGS's methods to estimate take by
incidental harassment and present the applicant's estimates of the
numbers of marine mammals that could be affected during the proposed
seismic program in the deep water of the northwestern GOM. The
estimates are based on a consideration of the number of marine mammals
that could be harassed by approximately 1,480 km (799.1 nmi) of seismic
operations with the two GI airgun array to be used. The size of the
proposed 2D seismic survey area in 2013 is approximately 356 km\2\
(103.8 nmi\2\) (approximately 445 km\2\ [129.7 nmi\2\]), as depicted in
Figure 1 of the IHA application.
USGS assumes that, during simultaneous operations of the airgun
array and the other sources, any marine mammals close enough to be
affected by the sub-bottom profiler would already be affected by the
airguns. However, whether or not the airguns are operating
simultaneously with the other sources, marine mammals are expected to
exhibit no more than short-term and inconsequential responses to the
sub-bottom profiler given their characteristics (e.g., narrow,
downward-directed beam) and other considerations described previously.
Such reactions are not considered to constitute ``taking'' (NMFS,
2001). Therefore, USGS provides no additional allowance for animals
that could be affected by sound sources other than airguns.
USGS used spring densities reported in Table A-9 of Appendix A of
the Bureau of Ocean Energy Management, Regulation and Enforcement's
(BOEMRE, now the Bureau of Ocean Energy Management [BOEM] and Bureau of
Safety and Environmental Enforcement [BSEE]) ``Request for incidental
take regulations governing seismic surveys on the Outer Continental
Shelf (OCS) of the Gulf of Mexico'' (BOEMRE, 2011). Those densities
were calculated from the U.S. Navy's ``OPAREA Density Estimates''
(NODE) database (DoN, 2007b). The density estimates are based on the
NMFS-Southeast Fisheries Science Center (SEFSC) shipboard surveys
conducted from 1994 to 2006 and were derived using a model-based
approach and statistical analysis of the existing survey data. The
outputs from the NODE database are four seasonal surface density plots
of the GOM for each of the marine mammal species occurring there. Each
of the density plots was overlaid with the boundaries of the 9 acoustic
model regions used in Appendix A of BOEMRE (2011). USGS used the
densities for Acoustic Model Region 8, which corresponds roughly with
the deep waters (greater than 1,000 m) of the BOEMRE GOM Central
Planning
[[Page 11841]]
Area, and includes the GC955 and WR313 study sites.
Table 3--Estimated Densities and Possible Number of Marine Mammal Species That Might Be Exposed to Greater Than
or Equal to 160 dB During USGS's Proposed Seismic Survey (Ensonified Area 445.4 km\2\) in the Deep Water of the
Northwestern GOM, April to May, 2013
----------------------------------------------------------------------------------------------------------------
Calculated
take (i.e.,
estimated
Density \a\ number of Approximate percentage Requested take
Species (/ individuals of best population authorization
1,000 km\2\) exposed to estimate of stock \3\
sound levels (calculated take) \2\
>= 160 dB re 1
[micro]Pa) \1\
----------------------------------------------------------------------------------------------------------------
Mysticetes
----------------------------------------------------------------------------------------------------------------
North Atlantic right whale............ NA NA NA...................... NA
Humpback whale........................ NA NA NA...................... NA
Minke whale........................... NA NA NA...................... NA
Bryde's whale......................... 0.1 0 0....................... 0
Sei whale............................. NA NA NA...................... NA
Fin whale............................. NA NA NA...................... NA
Blue whale............................ NA NA NA...................... NA
----------------------------------------------------------------------------------------------------------------
Odontocetes
----------------------------------------------------------------------------------------------------------------
Sperm whale........................... 4.9 2 0.18 (0.12)............. 3
Kogia spp. (Pygmy and dwarf sperm 2.1 1 0.62 (0.31)--Pygmy sperm 2
whale). whale.
0.44 (0.22)--Dwarf sperm
whale.
Small (Mesoplodon and Cuvier's) beaked 3.7 2 3.51 (3.51)--Mesoplodon 2
whale. beaked whale.
3.1 (3.1)--Cuvier's
beaked whale.
Killer whale.......................... 0.40 0 0....................... 0
Short-finned pilot whale.............. 6.3 3 2.65 (0.42)............. 19
False killer whale.................... 2.7 1 4.63 (0.13)............. 36
Melon-headed whale.................... 9.1 4 5.17 (0.18)............. 118
Pygmy killer whale.................... 1.1 0 0....................... 0
Risso's dolphin....................... 10.0 4 0.57 (0.25)............. 9
Bottlenose dolphin.................... 4.8 2 NA (NA)--32 Northern GOM 18
Bay, Sound and Estuary
stocks.
NA (NA)--Northern GOM
continental shelf stock.
0.23 (0.03)--GOM eastern
coastal stock.
0.73 (0.08)--GOM
northern coastal stock.
NA (NA)--GOM western
coastal stock.
0.49 (0.05)--Northern
GOM oceanic stock.
Rough-toothed dolphin................. 6.7 3 0.6 (0.11).............. 16
Fraser's dolphin...................... 1.9 1 NA (NA)................. 117
Striped dolphin....................... 51.5 23 1.35 (0.69)............. 45
Pantropical spotted dolphin........... 582.6 259 0.76 (0.76)............. 259
Atlantic spotted dolphin.............. 2.2 1 NA (NA)................. 15
Spinner dolphin....................... 72.6 32 4.98 (1.61)............. 99
Clymene dolphin....................... 45.6 20 1.14 (0.3).............. 75
----------------------------------------------------------------------------------------------------------------
NA = Not available or not assessed.
\1\ Calculated take is density times the area ensonified to >160 dB (rms) around the planned seismic lines,
increased by 25%.
\2\ Stock sizes are best populations from NMFS Stock Assessment Reports (see Table 2 above).
\3\ Requested Take Authorization increased to mean group size.
USGS estimated the number of different individuals that may be
exposed to airgun sounds with received levels greater than or equal to
160 dB re 1 [mu]Pa (rms) on one or more occasions by considering the
total marine area that would be within the 160 dB radius around the
operating airgun array on at least one occasion and the expected
density of marine mammals in the area. The number of possible exposures
(including repeat exposures of the same individuals) can be estimated
by considering the total marine area that would be within the 160 dB
radius around the operating airguns, excluding areas of overlap. During
the proposed survey, the transect lines in the square
[[Page 11842]]
grid are closely spaced (approximately 100 m [328.1 ft] apart at the
GC955 site and 250 m [820.2 ft] apart at the WR313 site) relative to
the 160 dB distance (670 m [2,198.2 ft]). Thus, the area including
overlap is 6.5 times the area excluding overlap at GC955 and 5.3 times
the area excluding overlap at WR313, so a marine mammal that stayed in
the survey areas during the entire survey could be exposed
approximately 6 or 7 times on average. While some individuals may be
exposed multiple times since the survey tracklines are spaced close
together; however, it is unlikely that a particular animal would stay
in the area during the entire survey.
The number of different individuals potentially exposed to received
levels greater than or equal to 160 re 1 [mu]Pa (rms) was calculated by
multiplying:
(1) The expected species density (in number/km\2\), times
(2) The anticipated area to be ensonified to that level during
airgun operations excluding overlap.
The area expected to be ensonified was determined by entering the
planned survey lines into a MapInfo GIS, using the GIS to identify the
relevant areas by ``drawing'' the applicable 160 dB buffer (see Table 1
of the IHA application) around each seismic line, and then calculating
the total area within the buffers.
Applying the approach described above, approximately 356 km\2\
(approximately 445 km\2\ including the 25% contingency) would be within
the 160 dB isopleth on one or more occasions during the proposed
survey. The take calculations within the study sites do not explicitly
add animals to account for the fact that new animals (i.e., turnover)
are not accounted for in the initial density snapshot and animals could
also approach and enter the area ensonified above 160 dB; however,
studies suggest that many marine mammals will avoid exposing themselves
to sounds at this level, which suggests that there would not
necessarily be a large number of new animals entering the area once the
seismic survey started. Because this approach for calculating take
estimates does not allow for turnover in the marine mammal populations
in the area during the course of the survey, the actual number of
individuals exposed may be underestimated, although the conservative
(i.e., probably overestimated) line-kilometer distances used to
calculate the area may offset this. Also, the approach assumes that no
cetaceans will move away or toward the tracklines as the Pelican
approaches in response to increasing sound levels before the levels
reach 160 dB. Another way of interpreting the estimates that follow is
that they represent the number of individuals that are expected (in
absence of a seismic program) to occur in the waters that will be
exposed to greater than or equal to 160 dB (rms).
USGS's estimates of exposures to various sound levels assume that
the proposed surveys will be carried out in full (i.e., approximately 8
days of seismic airgun operations for the two study sites,
respectively); however, the ensonified areas calculated using the
planned number of line-kilometers have been increased by 25% to
accommodate lines that may need to be repeated, equipment testing,
account for repeat exposure, etc. As is typical during offshore ship
surveys, inclement weather and equipment malfunctions are likely to
cause delays and may limit the number of useful line-kilometers of
seismic operations that can be undertaken. The estimates of the numbers
of marine mammals potentially exposed to 160 dB (rms) received levels
are precautionary and probably overestimate the actual numbers of
marine mammals that could be involved. These estimates assume that
there will be no weather, equipment, or mitigation delays, which is
highly unlikely.
Table 3 (Table 3 of the IHA application) shows the estimates of the
number of different individual marine mammals anticipated to be exposed
to greater than or equal to 160 dB re 1 [mu]Pa (rms) during the seismic
survey if no animals moved away from the survey vessel. The requested
take authorization is given in the far right column of Table 3 (Table 3
of the IHA application). The requested take authorization has been
increased to the average mean group sizes in the GOM in 1996 to 2001
(Mullin and Fulling, 2004) and 2003 and 2004 (Mullin, 2007) in cases
where the calculated number of individuals exposed was between one and
the mean group size.
The estimate of the number of individual cetaceans that could be
exposed to seismic sounds with received levels greater than or equal to
160 dB re 1 [mu]Pa (rms) during the proposed survey is 358,
respectively (with 25% contingency) (see Table 3 of the IHA
application). That total (with 25% contingency) includes 0 baleen
whales, 1 dwarf/pygmy sperm whale, and 2 beaked whales, (including
Cuvier's and Mesoplodon beaked whales) could be taken by Level B
harassment during the proposed seismic survey. Most of the cetaceans
potentially taken by Level B harassment are delphinids; pantropical
spotted, spinner, Clymene, and striped dolphins are estimated to be the
most common species in the area, with estimates of 259, 32, 20, and 23,
which would represent 0.76, 0.3, 1.61, and 0.69% of the affected
populations or stocks, respectively.
Encouraging and Coordinating Research
USGS will coordinate the planned marine mammal monitoring program
associated with the proposed seismic survey with any parties that
express interest in this activity.
Negligible Impact and Small Numbers Analysis Determination
NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ``an
impact resulting from the specified activity that cannot be reasonably
expected to, and is not reasonably likely to, adversely affect the
species or stock through effects on annual rates of recruitment or
survival.''
In making a negligible impact determination, NMFS evaluated factors
such as:
(1) The number of anticipated injuries, serious injuries, or
mortalities;
(2) The number, nature, and intensity, and duration of Level B
harassment (all relatively limited); and
(3) The context in which the takes occur (i.e., impacts to areas of
significance, impacts to local populations, and cumulative impacts when
taking into account successive/contemporaneous actions when added to
baseline data);
(4) The status of stock or species of marine mammals (i.e.,
depleted, not depleted, decreasing, increasing, stable, impact relative
to the size of the population);
(5) Impacts on habitat affecting rates of recruitment/survival; and
(6) The effectiveness of monitoring and mitigation measures.
As described above and based on the following factors, the
specified activities associated with the marine seismic survey are not
likely to cause PTS, or other non-auditory injury, serious injury, or
death. The factors include:
(1) The likelihood that, given sufficient notice through relatively
slow ship speed, marine mammals are expected to move away from a noise
source that is annoying prior to its becoming potentially injurious;
(2) The potential for temporary or permanent hearing impairment is
relatively low and would likely be avoided through the implementation
of the shut-down measures;
No injuries, serious injuries, or mortalities are anticipated to
occur as a result of the USGS's planned marine
[[Page 11843]]
seismic surveys, and none are proposed to be authorized by NMFS. Table
3 of this document outlines the number of requested Level B harassment
takes that are anticipated as a result of these activities. Due to the
nature, degree, and context of Level B (behavioral) harassment
anticipated and described (see ``Potential Effects on Marine Mammals''
section above) in this notice, the activity is not expected to impact
rates of annual recruitment or survival for any affected species or
stock, particularly given the NMFS and the applicant's proposal to
implement mitigation, monitoring, and reporting measures to minimize
impacts to marine mammals.
For the other marine mammal species that may occur within the
proposed action area, there are no known designated or important
feeding and/or reproductive areas. Many animals perform vital
functions, such as feeding, resting, traveling, and socializing, on a
diel cycle (i.e., 24 hr cycle). Behavioral reactions to noise exposure
(such as disruption of critical life functions, displacement, or
avoidance of important habitat) are more likely to be significant if
they last more than one diel cycle or recur on subsequent days
(Southall et al., 2007). Additionally, the seismic survey will be
increasing sound levels in the marine environment in a relatively small
area surrounding the vessel (compared to the range of the animals),
which is constantly travelling over distances, and some animals may
only be exposed to and harassed by sound for less than day.
Of the 28 marine mammal species under NMFS jurisdiction that may or
are known to likely to occur in the study area, six are listed as
threatened or endangered under the ESA: North Atlantic right, humpback,
sei, fin, blue, and sperm whales. These species are also considered
depleted under the MMPA. Of these ESA-listed species, incidental take
has been requested to be authorized for sperm whales. There is
generally insufficient data to determine population trends for the
other depleted species in the study area. To protect these animals (and
other marine mammals in the study area), USGS must cease or reduce
airgun operations if any marine mammal enters designated zones. No
injury, serious injury, or mortality is expected to occur and due to
the nature, degree, and context of the Level B harassment anticipated,
and the activity is not expected to impact rates of recruitment or
survival.
As mentioned previously, NMFS estimates that 19 species of marine
mammals under its jurisdiction could be potentially affected by Level B
harassment over the course of the IHA. The population estimates for the
marine mammal species that may be taken by Level B harassment were
provided in Table 3 of this document.
NMFS's practice has been to apply the 160 dB re 1 [mu]Pa (rms)
received level threshold for underwater impulse sound levels to
determine whether take by Level B harassment occurs. Southall et al.
(2007) provide a severity scale for ranking observed behavioral
responses of both free-ranging marine mammals and laboratory subjects
to various types of anthropogenic sound (see Table 4 in Southall et al.
[2007]).
NMFS has preliminarily determined, provided that the aforementioned
mitigation and monitoring measures are implemented, the impact of
conducting a low-energy marine seismic survey in the deep water of the
northwestern GOM, April to May, 2013, may result, at worst, in a
modification in behavior and/or low-level physiological effects (Level
B harassment) of certain species of marine mammals.
While behavioral modifications, including temporarily vacating the
area during the operation of the airgun(s), may be made by these
species to avoid the resultant acoustic disturbance, the availability
of alternate areas within these areas for species and the short and
sporadic duration of the research activities, have led NMFS to
preliminary determine that the taking by Level B harassment from the
specified activity will have a negligible impact on the affected
species in the specified geographic region. NMFS believes that the
length of the seismic survey, the requirement to implement mitigation
measures (e.g., shut-down of seismic operations), and the inclusion of
the monitoring and reporting measures, will reduce the amount and
severity of the potential impacts from the activity to the degree that
it will have a negligible impact on the species or stocks in the action
area.
NMFS has preliminary determined, provided that the aforementioned
mitigation and monitoring measures are implemented, that the impact of
conducting a marine seismic survey in the deep water of the Gulf of
Mexico, April to May, 2013, may result, at worst, in a temporary
modification in behavior and/or low-level physiological effects (Level
B harassment) of small numbers of certain species of marine mammals.
See Table 3 for the requested authorized take numbers of marine
mammals.
Impact on Availability of Affected Species or Stock for Taking for
Subsistence Uses
Section 101(a)(5)(D) of the MMPA also requires NMFS to determine
that the authorization will not have an unmitigable adverse effect on
the availability of marine mammal species or stocks for subsistence
use. There are no relevant subsistence uses of marine mammals in the
study area (in the deep water of the northwest GOM) that implicate MMPA
section 101(a)(5)(D).
Endangered Species Act
Of the species of marine mammals that may occur in the proposed
survey area, several are listed as endangered under the ESA, including
the North Atlantic right, humpback, sei, fin, blue, and sperm whales.
USGS did not request take of endangered North Atlantic right, humpback,
sei, fin, and blue whales due to the low likelihood of encountering
this species during the cruise. Under section 7 of the ESA, USGS has
initiated formal consultation with the NMFS, Office of Protected
Resources, Endangered Species Act Interagency Cooperation Division, on
this proposed seismic survey. NMFS's Office of Protected Resources,
Permits and Conservation Division, has initiated formal consultation
under section 7 of the ESA with NMFS's Office of Protected Resources,
Endangered Species Act Interagency Cooperation Division, to obtain a
Biological Opinion evaluating the effects of issuing the IHA on
threatened and endangered marine mammals and, if appropriate,
authorizing incidental take. NMFS will conclude formal section 7
consultation prior to making a determination on whether or not to issue
the IHA. If the IHA is issued, USGS, in addition to the mitigation and
monitoring requirements included in the IHA, will be required to comply
with the Terms and Conditions of the Incidental Take Statement
corresponding to NMFS's Biological Opinion issued to both USGS and
NMFS's Office of Protected Resources.
National Environmental Policy Act
With USGS's complete application, they provided NMFS a draft
``Environmental Assessment and Determination Pursuant to the National
Environmental Policy Act, 42 U.S.C. 4321 et seq. and Executive Order
12114 Low-Energy Marine Seismic Survey by the U.S. Geological Survey in
the Deepwater Gulf of Mexico, April-May 2013,'' which incorporates a
draft ``Environmental Assessment of Low-Energy Marine Geophysical
Survey by the U.S. Geological Survey in the
[[Page 11844]]
Northwestern Gulf of Mexico, April-May 2013,'' prepared by LGL Ltd.,
Environmental Research Associates on behalf of USGS. The EA analyzes
the direct, indirect, and cumulative environmental impacts of the
proposed specified activities on marine mammals including those listed
as threatened or endangered under the ESA. Prior to making a final
decision on the IHA application, NMFS will either prepare an
independent EA, or, after review and evaluation of the USGS EA for
consistency with the regulations published by the Council of
Environmental Quality (CEQ) and NOAA Administrative Order 216-6,
Environmental Review Procedures for Implementing the National
Environmental Policy Act, adopt the USGS EA and make a decision of
whether or not to issue a Finding of No Significant Impact (FONSI).
Proposed Authorization
NMFS proposes to issue an IHA to USGS for conducting a low-energy
marine seismic survey in the deep water of the northwestern GOM,
provided the previously mentioned mitigation, monitoring, and reporting
requirements are incorporated. The duration of the IHA would not exceed
one year from the date of its issuance.
Information Solicited
NMFS requests interested persons to submit comments and information
concerning this proposed project and NMFS's preliminary determination
of issuing an IHA (see ADDRESSES). Concurrent with the publication of
this notice in the Federal Register, NMFS is forwarding copies of this
application to the Marine Mammal Commission and its Committee of
Scientific Advisors.
Helen M. Golde,
Acting Director, Office of Protected Resources, National Marine
Fisheries Service.
[FR Doc. 2013-03837 Filed 2-19-13; 8:45 am]
BILLING CODE 3510-22-P