[Federal Register Volume 76, Number 135 (Thursday, July 14, 2011)]
[Notices]
[Pages 41463-41486]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-17765]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
RIN 0648-XA568
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to a Marine Geophysical Survey in the
Arctic Ocean, September-October 2011
AGENCY: Commerce, National Oceanic and Atmospheric Administration
(NOAA), National Marine Fisheries Service (NMFS).
ACTION: Notice; proposed incidental harassment authorization; request
for comments.
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SUMMARY: NMFS has received an application from the University of Alaska
Geophysics Institute (UAGI) for an Incidental Harassment Authorization
(IHA) to take marine mammals, by harassment, incidental to conducting a
marine geophysical seismic survey in the Arctic Ocean during September-
October 2011. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS
is requesting comments on its proposal to issue an IHA to UAGI to take,
by Level B harassment only, several species of marine mammals during
the specified activity.
DATES: Comments and information must be received no later than August
15, 2011.
ADDRESSES: Comments on the application should be addressed to P.
Michael Payne, Chief, Permits, Conservation and Education Division,
Office of Protected Resources, National Marine Fisheries Service, 1315
East-West Highway, Silver Spring, MD 20910. The mailbox address for
providing e-mail comments is [email protected]. NMFS is not
responsible for e-mail comments sent to addresses other than the one
provided here. Comments sent via e-mail, including all attachments,
must not exceed a 10-megabyte file size.
Instructions: All comments received are a part of the public record
and will generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm without change. All Personal Identifying Information
(for example, name, address, etc.) voluntarily submitted by the
commenter may be publicly accessible. Do not submit Confidential
Business Information or otherwise sensitive or protected information.
A copy of the application used in this document may be obtained by
writing to the address specified above, telephoning the contact listed
below (see FOR FURTHER INFORMATION CONTACT), or visiting the Internet
at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm.
The National Science Foundation (NSF), which is providing funding
to UAGI to conduct the survey, has prepared a draft ``Environmental
Assessment of a Marine Geophysical Survey by the R/V Marcus G. Langseth
in the Arctic Ocean, September-October 2011,'' prepared by LGL Ltd.,
Environmental Research Associates (LGL), on behalf of UAGI and NSF,
which is also available at the same internet address. Documents cited
in this notice may also be viewed, by appointment, during regular
business hours, at the aforementioned address.
FOR FURTHER INFORMATION CONTACT: Candace Nachman, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.)
direct the Secretary of Commerce to allow, upon request, the
incidental, but not intentional, taking of small numbers of marine
mammals by U.S. citizens who engage in a specified activity (other than
commercial fishing) within a specified geographical region if certain
findings are made and either regulations are issued or, if the taking
is limited to harassment, a notice of a proposed authorization is
provided to the public for review.
Authorization for incidental takings shall be granted if NMFS finds
that the taking will have a negligible impact on the species or
stock(s), will not have an unmitigable adverse impact on the
availability of the species or stock(s) for subsistence uses (where
relevant), and if the permissible methods of taking and requirements
pertaining to the mitigation, monitoring, and reporting of such takings
are set forth. NMFS has defined ``negligible impact'' in 50 CFR 216.103
as ``* * * an impact resulting from the specified activity that cannot
be reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.''
Section 101(a)(5)(D) of the MMPA established an expedited process
by which citizens of the U.S. can apply for an authorization to
incidentally take small numbers of marine mammals by harassment.
Section 101(a)(5)(D) establishes a 45-day time limit for NMFS review of
an application followed by a 30 day public notice and comment period on
any proposed
[[Page 41464]]
authorizations for the incidental harassment of marine mammals. Within
45 days of the close of the comment period, NMFS must either issue or
deny the authorization.
Except with respect to certain activities not pertinent here, the
MMPA defines ``harassment'' as:
any act of pursuit, torment, or annoyance which (i) has the
potential to injure a marine mammal or marine mammal stock in the
wild [``Level A harassment'']; or (ii) has the potential to disturb
a marine mammal or marine mammal stock in the wild by causing
disruption of behavioral patterns, including, but not limited to,
migration, breathing, nursing, breeding, feeding, or sheltering
[``Level B harassment''].
Summary of Request
NMFS received an application on March 4, 2011, from UAGI for the
taking, by harassment, of marine mammals incidental to conducting a
marine geophysical seismic survey in the Arctic Ocean. NMFS reviewed
UAGI's application and identified a number of issues requiring further
clarification. After addressing comments from NMFS, UAGI modified its
application and submitted a revised application on May 10, 2011. The
May 10, 2011, application is the one available for public comment (see
ADDRESSES) and considered by NMFS for this proposed IHA.
UAGI proposes to conduct a 2D seismic survey in the Arctic Ocean,
Chukchi Sea, in both international waters and within the U.S. Exclusive
Economic Zone (EEZ) in water depths ranging from 30-3,800 m (98-12,467
ft). UAGI plans to conduct the proposed seismic survey from September 5
through October 9, 2011, which includes vessel transit time from Dutch
Harbor.
UAGI plans to use one source vessel, the R/V Marcus G. Langseth
(Langseth) and a seismic airgun array to collect seismic reflection
data across the transition from the Chukchi Shelf to the Chukchi
Borderland to define the apparent change in structure between two large
continental blocks. In addition to the proposed operations of the
seismic airgun array, UAGI intends to operate a multibeam echosounder
(MBES) and a sub-bottom profiler (SBP) continuously throughout the
survey. A 75-kilohertz (kHz) acoustic Doppler current profiler (ADCP)
may also be used.
Acoustic stimuli (i.e., increased underwater sound) generated
during the operation of the seismic airgun array may have the potential
to cause a short-term behavioral disturbance for marine mammals in the
proposed survey area. This is the principal means of marine mammal
taking associated with these activities, and UAGI has requested an
authorization to take 11 species of marine mammals by Level B
harassment. These species are: Bowhead whale; gray whale; humpback
whale; minke whale; fin whale; beluga whale; killer whale; bearded
seal; spotted seal; ringed seal; and ribbon seal. Take is not expected
to result from the use of the MBES or SBP, for reasons discussed later
in this notice; nor is take expected to result from collision with the
vessel because it is a single vessel moving at a relatively slow speed
during seismic acquisition within the survey, for a relatively short
period of time (approximately 35 days). It is likely that any marine
mammal would be able to avoid the vessel.
Description of the Specified Activity
UAGI's survey is proposed to occur in the area 72.5-77[deg] N. and
160-175[deg] W. in international waters and within the U.S. EEZ (see
Figure 1 in UAGI's application). The project is scheduled to occur from
September 5-October 9, 2011. Some minor deviation from these dates is
possible, depending on logistics and weather. Therefore, NMFS is
proposing to make the IHA valid from September 5-October 23, 2011. The
vessel will not be able to remain in the area once ice begins to form,
as the Langseth is not an icebreaker. The Langseth would depart from
Dutch Harbor on September 5, 2011, and sail northeast to arrive at
approximately 72.5[deg] N., 162[deg] W., where the seismic survey will
begin, more than 200 km (124 mi) from Barrow. The entire cruise would
last for approximately 35 days, and it is estimated that the total
seismic survey time will be approximately 25 days, depending on ice
conditions. Seismic survey work is scheduled to terminate near the
starting point at approximately 72.4[deg] N., 164[deg] W. on October 6;
the vessel would then sail south to Dutch Harbor for arrival on October
9. There could be extra days of seismic shooting, if the collected data
are of substandard quality.
The proposed survey will include collection of seismic reflection
data across the transition from the Chukchi Shelf to the Chukchi
Borderland to define the apparent change in structure between two large
continental blocks. This study will test existing tectonic models and
develop new constraints on the development of the Amerasian Basin and
will substantially advance our understanding of the Mesozoic history of
this basin. In addition, these data will enable the formulation of new
tectonic models for the history of this region, which will improve our
understanding of the surrounding continents.
The survey will involve one source vessel, the Langseth, which is
operated by Lamont-Doherty Earth Observatory (L-DEO), a part of
Columbia University, under a cooperative agreement with NSF. The
Langseth will deploy an array of 10 airguns (1,830 in\3\) as an energy
source at a tow depth of 6 m (19.7 ft). The receiving system will
consist of a 2-km (1.2-mi) long hydrophone streamer. As the airgun
array is towed along the survey lines, the hydrophone streamer will
receive the returning acoustic signals and transfer the data to the on-
board processing system. In addition, at least 72 sonobuoys will be
deployed in order to record seismic refraction data. The Langseth will
be avoiding the ice edge, and an ice expert will be available to
provide daily guidance and to predict ice movements.
The proposed program will consist of a total of approximately 5,502
km (3,419 mi) of survey lines, not including transits to and from the
survey area when airguns will not be in use (see Figure 1 in UAGI's
application). Water depths within the study area range from
approximately 30-3,800 m (98-12,467). Just over half of the survey
effort (55%) will occur in water 100-1,000 m (328-3,281 ft) deep, 32%
will take place in water >1,000 m (3,281 ft) deep, and 13% will occur
in water depths <100 m (328 ft). There will be additional seismic
operations in the survey area associated with turns, airgun testing,
and repeat coverage of any areas where initial data quality is sub-
standard. In addition to the operations of the airgun array, a
Kongsberg EM 122 MBES and a Knudsen 320B SBP will also be operated from
the Langseth continuously throughout the cruise. A 75-kHz ADCP may also
be used.
All planned geophysical data acquisition activities will be
conducted by L-DEO with on-board assistance by the scientists who have
proposed the study. The Principal Investigator is Dr. Bernard Coakley
of UAGI. The vessel will be self-contained, and the crew will live
aboard the vessel for the entire cruise.
Vessel Specifications
The Langseth will tow the 10-airgun array along predetermined
lines. The vessel will also tow the hydrophone streamer and deploy the
sonobuoys. When the Langseth is towing the airgun array, as well as the
hydrophone streamer, the turning rate of the vessel while the gear is
deployed is limited. Thus, the maneuverability of the vessel is limited
during operations with the streamer.
[[Page 41465]]
The vessel has a length of 71.5 m (235 ft); a beam of 17 m (56 ft);
a maximum draft of 5.9 m (19 ft); and a gross tonnage of 3,834. The
Langseth was designed as a seismic research vessel with a propulsion
system designed to be as quiet as possible to avoid interference with
the seismic signals emanating from the airgun array. The ship is
powered by two 3,550 horsepower (hp) Bergen BRG-6 diesel engines which
drive two propellers directly. Each propeller has four blades, and the
shaft typically rotates at 750 revolutions per minute. The vessel also
has an 800 hp bowthruster, which is not used during seismic
acquisition. The Langseth's operation speed during seismic acquisition
is typically 7.4 to 9.3 km per hour (hr) (km/hr) (4 to 5 knots [kts]).
When not towing seismic survey gear, the Langseth typically cruises at
18.5 km/hr (10 kts). The Langseth has a range of 25,000 km (15,534 mi)
(the distance the vessel can travel without refueling).
The Langseth is not an ice-strengthened vessel and must especially
consider safety-of-operations while towing a significant amount of
equipment behind the vessel; it therefore cannot operate in ice
conditions that would pose serious hazards to the vessel and crew.
After consideration of the operational challenges, however, NSF and L-
DEO concluded that the Langseth would be able to support the activity
if it remained in ice-free waters. An ice expert would be available to
help provide guidance during any operations.
The vessel also has an observation tower from which protected
species visual observers (PSVO) will watch for marine mammals before
and during the proposed airgun operations. When stationed on the
observation platform, the PSVO's eye level will be approximately 21.5 m
(71 ft) above sea level, providing the PSVO an unobstructed view around
the entire vessel.
Acoustic Source Specifications
(1) Airgun Array
During the survey, the airgun array to be used will consist of 10
airguns, with a total volume of approximately 1,830 cubic inches
(in\3\). The airgun array will consist of a mixture of Bolt 1500LL and
Bolt 1900LLX airguns, set in a typical configuration of one of the
Langseth's four linear arrays or ``strings'' (see Figure 2 in UAGI's
application); the first and last airguns in the strings are spaced 16 m
(52 ft) apart. The airgun array will be towed approximately 100 m (328
ft) behind the Langseth. The shot interval will be 15 seconds (s). The
firing pressure of the array is 1,950 pounds per square inch. During
firing, a brief (approximately 0.1 s) pulse of sound is emitted. The
airguns will be silent during the intervening periods.
The tow depth of the array will be 6 m (19.7 ft). Because the
actual source is a distributed sound source (10 airguns) rather than a
single point source, the highest sound levels measurable at any
location in the water will be less than the nominal source level. In
addition, the effective source level for sound propagating in near-
horizontal directions will be substantially lower than the nominal
source level applicable to downward propagation because of the
directional nature of the sound from the airgun array.
(2) MBES
The Langseth will operate a Kongsberg EM 122 MBES concurrently
during airgun operations to map characteristics of the ocean floor. The
hull-mounted MBES emits brief pulses of sound (also called a ping)
(10.5 to 13 kHz, usually 12 kHz) in a fan-shaped beam that extends
downward and to the sides of the ship. The transmitting beamwidth is
1[deg] fore-aft and 150[deg] athwartship, and the maximum source level
is 242 dB re 1 [mu]Pa (rms).
For deep-water operations, each ping consists of eight (in water
greater than 1,000 m [3,281 ft]) or four (in water less than 1,000 m
[3,281 ft]) successive, fan-shaped transmissions, each ensonifying a
sector that extends 1[deg] fore-aft. Continuous-wave pulses increase
from 2 to 15 milliseconds (ms) long in water depths up to 2,600 m
(8,530.2 ft), and frequency-modulated chirp pulses up to 100 ms long
are used in water greater than 2,600 m (8,530.2 ft). The successive
transmissions span an overall cross-track angular extent of about
150[deg], with 2 ms gaps between the pulses for successive sectors.
(3) SBP
The Langseth will also operate a Knudsen 320B SBP continuously
throughout the cruise simultaneously with the MBES to map and provide
information about the sedimentary features and bottom topography. The
beam is transmitted as a 27[deg] cone, which is directed downward by a
3.5 kHz transducer in the hull of the Langseth. The maximum output is
1,000 watts (204 dB re 1 [mu]Pa), but in practice, the output varies
with water depth. The pulse interval is 1 s, but a common mode of
operation is to broadcast five pings at 1-s intervals followed by a 5-s
pause.
(4) ADCP
The Ocean Surveyor 75 is an ADCP operating at a frequency of 75
kHz, producing a ping every 1.4 s. The system is a four-beam phased
array with a beam angle of 30[deg]. Each beam has a width of 4[deg],
and there is no overlap. Maximum output is 1 kilowatt, with a maximum
depth range of 700 m (2,296.6 ft).
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 root mean square (rms). Root mean
square, 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 rms unless otherwise noted. SPL does not take
the duration of a sound into account.
Predicted Sound Levels
Received sound levels have been predicted by Marine Acoustics, Inc.
(MAI), in relation to distance and direction from the airguns, for the
10-airgun array. The MAI model was site specific; sound velocity
profiles, bathymetry, and bottom composition were used to model
propagation at seven sites 120-2,727 m (328-8,947 ft) deep in the
survey area that represented different physiographic provinces
described by Jakobsson et al. (2003). The source model used was the
CASS/GRAB model, and propagation was modeled using the Range-Dependent
Acoustic Model (RAM) (Zingarelli and King, 2005). The detailed modeling
report can be found in Appendix A1 of the draft EA (see ADDRESSES).
Received sound levels for a single 40-in\3\ airgun were modeled by
L-DEO. The tow depth has minimal effect on the maximum near-field
output and the shape of the frequency spectrum for the
[[Page 41466]]
single airgun; thus, the predicted exclusion zone radii are essentially
the same at different tow depths. As the L-DEO model does not allow for
bottom interactions, and thus is most directly applicable to deep water
and to relatively short ranges, correction factors were used to
estimate exclusion zone radii in shallow and intermediate-depth water
as was done for previous L-DEO surveys from the Langseth. A detailed
description of the L-DEO modeling effort is provided in Appendix A2 of
the draft EA.
Table 1 in this document and Table 1 in UAGI's application show the
distances at which three rms sound levels are expected to be received
from the 10-airgun array and a single airgun. For the 10-airgun array,
distances were modeled at seven sites; the distances in Table 1 are the
averages from the sites in each depth range.
Table 1--Maximum Predicted Distances to Which Sound Levels >=190, 180, and 160 dB re 1 [mu]Pa (rms) Could Be
Received in Various Water-Depth Categories During the Proposed Survey in the Arctic Ocean. The Distances for the
10-Airgun Array Are the Averages of Modeled 95% Percentile Distances at Modeling Sites in Each Depth Range
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Predicted RMS radii (m)
Source and volume Tow depth Water depth --------------------------------------
(m) 190 dB 180 dB 160 dB
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Single Bolt...................... ........... Deep (>1000 m)........... 12 40 385
6 Intermediate (100-1000 m) 18 60 578
........... Shallow (<100)........... 150 296 1,050
1 string......................... ........... Deep (>1000 m)........... 130 425 14,070
10 airguns....................... 6 Intermediate (200-1000 m) 130 1400 13,980
1830 in\3\....................... ........... Shallow (<200)........... 190 1870 14,730
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* The tow depth has minimal effect on the maximum near-field output and the shape of the frequency spectrum for
the single 40 in\3\ airgun; thus, the predicted safety radii are essentially the same at any tow depth.
NMFS expects that acoustic stimuli resulting from the proposed
operation of the single airgun or the 10 airgun array has the potential
to harass marine mammals, incidental to the conduct of the proposed
seismic survey. NMFS expects these disturbances to be temporary and
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. NMFS does not expect that the
movement of the Langseth, during the conduct of the seismic survey, has
the potential to harass marine mammals because of the relatively slow
operation speed of the vessel (4-5 kts [7.4 to 9.3 km/hr]) during
seismic data acquisition.
Description of Marine Mammals in the Area of the Specified Activity
The Chukchi Sea supports a diverse assemblage of marine mammals,
including: Bowhead, gray, beluga, killer, minke, humpback, and fin
whales; harbor porpoise; ringed, ribbon, spotted, and bearded seals;
narwhals; polar bears; and walruses. The bowhead, humpback, and fin
whales are listed as endangered, and the polar bear is listed as
threatened under the U.S. Endangered Species Act of 1973 (ESA; 16
U.S.C. 1531 et seq.). All of these species are also considered depleted
under the MMPA. On December 10, 2010, NMFS published a notification of
proposed threatened status for subspecies of the ringed seal (75 FR
77476) and a notification of proposed threatened and not warranted
status for subspecies and distinct population segments of the bearded
seal (75 FR 77496) in the Federal Register. Neither species is
considered depleted under the MMPA.
The bowhead and beluga whales and the ringed and bearded seals are
the marine mammal species most likely to be encountered during this
survey, with the ringed seal being the most likely marine mammal
species to occur throughout the proposed survey area. Although humpback
and minke whales are uncommon in the Arctic Ocean, sightings of both
species have occurred in the Chukchi Sea in recent years (Brueggeman,
2009; Haley et al., 2010; Clarke et al., 2011).
There are scattered records of narwhal in Alaskan waters, where the
species is considered extralimital (Reeves et al., 2002). Harbor
porpoises occur mainly in shelf areas where they can dive to depths of
at least 220 m (722 ft) and stay submerged for more than 5 min (Harwood
and Wilson, 2001). This species prefers shallower waters, making it
unlikely that harbor porpoises would be encountered during the proposed
seismic survey. Because of the rarity of these two species in the
proposed survey area, they are not considered further in this document.
The polar bear and walrus are managed by the U.S. Fish and Wildlife
Service (USFWS) and are not considered further in this proposed IHA
notice.
Refer to Sections III and IV of UAGI's application for detailed
information regarding the abundance and distribution, seasonal
distribution, population status, and life history and behavior of these
species and their occurrence in the proposed project area. When
reviewing the application, NMFS determined that the species
descriptions provided by UAGI correctly characterized the abundance and
distribution, seasonal distribution, population status, and life
history and behavior of each species. Additional information can also
be found in the NMFS Stock Assessment Reports (SAR). The 2010 Alaska
Marine Mammal SAR is available on the Internet at: http://www.nmfs.noaa.gov/pr/pdfs/sars/ak2010.pdf.
The application also presents how UAGI 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. UAGI's
methodology for estimating take is described further in the ``Estimated
Take by Incidental Harassment'' section found later in this document.
Brief Background on Marine Mammal Hearing
When considering the influence of various kinds of sound on the
marine environment, it is necessary to understand that different kinds
of marine life are sensitive to different frequencies of sound. Based
on available behavioral data, audiograms have been derived using
auditory evoked potentials, anatomical modeling, and other data,
Southall et al. (2007) designate ``functional hearing groups'' for
marine mammals and estimate the lower and upper frequencies of
[[Page 41467]]
functional hearing of the groups. The functional groups and the
associated frequencies are indicated below (though animals are less
sensitive to sounds at the outer edge of their functional range and
most sensitive to sounds of frequencies within a smaller range
somewhere in the middle of their functional hearing range):
Low frequency cetaceans (13 species of mysticetes):
Functional hearing is estimated to occur between approximately 7 Hz and
22 kHz (however, a study by Au et al. (2006) of humpback whale songs
indicate that the range may extend to at least 24 kHz);
Mid-frequency cetaceans (32 species of dolphins, six
species of larger toothed whales, and 19 species of beaked and
bottlenose whales): Functional hearing is estimated to occur between
approximately 150 Hz and 160 kHz;
High frequency cetaceans (eight species of true porpoises,
six species of river dolphins, Kogia, the franciscana, and four species
of cephalorhynchids): functional hearing is estimated to occur between
approximately 200 Hz and 180 kHz; and
Pinnipeds in Water: functional hearing is estimated to
occur between approximately 75 Hz and 75 kHz, with the greatest
sensitivity between approximately 700 Hz and 20 kHz.
As mentioned previously in this document, 11 marine mammal species
(seven cetacean and four pinniped species) are likely to occur in the
proposed survey area. Of the seven cetacean species likely to occur in
UAGI's propose survey area, five are classified as low frequency
cetaceans (i.e., bowhead, gray, humpback, minke, and fin whales) and
two are classified as mid-frequency cetaceans (i.e., beluga and killer
whales) (Southall et al., 2007).
Potential Effects of the Specified Activity 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). Takes by
serious injury or mortality are not anticipated to occur as a result of
the proposed activities.
Tolerance
Studies on marine mammals' tolerance to sound in the natural
environment are relatively rare. Richardson et al. (1995) define
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 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.
Malme et al., (1985) studied the responses of humpback whales on their
summer feeding grounds in southeast Alaska to seismic pulses from an
airgun with a total volume of 100 in \3\. They noted that the whales
did not exhibit persistent avoidance when exposed to the airgun and
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.
Weir (2008) observed marine mammal responses to seismic pulses from
a 24 airgun array firing a total volume of either 5,085 in \3\ or 3,147
in \3\ in Angolan waters between August 2004 and May 2005. Weir
recorded a total of 207 sightings of humpback whales (n = 66), sperm
whales (n = 124), and Atlantic spotted dolphins (n = 17) and reported
that there were no significant differences in encounter rates
(sightings/hr) for humpback and sperm whales according to the airgun
array's operational status (i.e., active versus silent).
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). Marine mammals are
highly dependent on sound, and their ability to recognize sound signals
amid other noise is important in communication, predator and prey
detection, and, in the case of toothed whales, echolocation. 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). Even in the absence of manmade sounds,
the sea is usually noisy. Background ambient noise often interferes
with or masks the ability of an animal to detect a sound signal even
when that signal is above its absolute hearing threshold. Natural
ambient noise includes contributions from wind, waves, precipitation,
other animals, and (at frequencies above 30 kHz) thermal noise
resulting from molecular agitation (Richardson et al., 1995).
Background noise also can include sounds from human activities. Masking
of natural sounds can result when human activities produce high levels
of background noise. Conversely, if the background level of underwater
noise is high (e.g., on a day with strong wind and high waves), an
anthropogenic noise source will not be detectable as far away as would
be possible under quieter conditions and will itself be masked.
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
northeast Pacific 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). 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
[[Page 41468]]
dominant components of airgun sounds, thus limiting the potential for
masking.
Although some degree of masking is inevitable when high levels of
manmade broadband sounds are introduced into the sea, marine mammals
have evolved systems and behavior that function to reduce the impacts
of masking. Structured signals, such as the echolocation click
sequences of small toothed whales, may be readily detected even in the
presence of strong background noise because their frequency content and
temporal features usually differ strongly from those of the background
noise (Au and Moore, 1988, 1990). The components of background noise
that are similar in frequency to the sound signal in question primarily
determine the degree of masking of that signal.
There is evidence of other marine mammal species continuing to call
in the presence of industrial activity. For example, bowhead whale
calls are frequently detected in the presence of seismic pulses,
although the number of calls detected may sometimes be reduced
(Richardson et al., 1986; Greene et al., 1999; Blackwell et al., 2009).
Additionally, annual acoustical monitoring near BP's Northstar
production facility during the fall bowhead migration westward through
the Beaufort Sea has recorded thousands of calls each year (for
examples, see Richardson et al., 2007; Aerts and Richardson, 2008).
Construction, maintenance, and operational activities have been
occurring from this facility for more than 10 years. To compensate and
reduce masking, some mysticetes may alter the frequencies of their
communication sounds (Richardson et al., 1995a; Parks et al., 2007).
Masking processes in baleen whales are not amenable to laboratory
study, and no direct measurements on hearing sensitivity are available
for these species. It is not currently possible to determine with
precision the potential consequences of temporary or local background
noise levels. However, Parks et al. (2007) found that right whales
altered their vocalizations, possibly in response to background noise
levels. For species that can hear over a relatively broad frequency
range, as is presumed to be the case for mysticetes, a narrow band
source may only cause partial masking. Richardson et al. (1995a) note
that a bowhead whale 20 km (12.4 mi) from a human sound source, such as
that produced during oil and gas industry activities, might hear strong
calls from other whales within approximately 20 km (12.4 mi), and a
whale 5 km (3.1 mi) from the source might hear strong calls from whales
within approximately 5 km (3.1 mi). Additionally, masking is more
likely to occur closer to a sound source, and distant anthropogenic
sound is less likely to mask short-distance acoustic communication
(Richardson et al., 1995a).
Redundancy and context can also facilitate detection of weak
signals. These phenomena may help marine mammals detect weak sounds in
the presence of natural or manmade noise. Most masking studies in
marine mammals present the test signal and the masking noise from the
same direction. The sound localization abilities of marine mammals
suggest that, if signal and noise come from different directions,
masking would not be as severe as the usual types of masking studies
might suggest (Richardson et al., 1995). The dominant background noise
may be highly directional if it comes from a particular anthropogenic
source such as a ship or industrial site. Directional hearing may
significantly reduce the masking effects of these noises by improving
the effective signal-to-noise ratio. In the cases of high-frequency
hearing by the bottlenose dolphin, beluga whale, and killer whale,
empirical evidence confirms that masking depends strongly on the
relative directions of arrival of sound signals and the masking noise
(Penner et al., 1986; Dubrovskiy, 1990; Bain et al., 1993; Bain and
Dahlheim, 1994). Toothed whales, and probably other marine mammals as
well, have additional capabilities besides directional hearing that can
facilitate detection of sounds in the presence of background noise.
There is evidence that some toothed whales can shift the dominant
frequencies of their echolocation signals from a frequency range with a
lot of ambient noise toward frequencies with less noise (Au et al.,
1974, 1985; Moore and Pawloski, 1990; Thomas and Turl, 1990; Romanenko
and Kitain, 1992; Lesage et al., 1999). A few marine mammal species are
known to increase the source levels or alter the frequency of their
calls in the presence of elevated sound levels (Dahlheim, 1987; Au,
1993; Lesage et al., 1993, 1999; Terhune, 1999; Foote et al., 2004;
Parks et al., 2007, 2009; Di Iorio and Clark, 2009; Holt et al., 2009).
These data demonstrating adaptations for reduced masking pertain
mainly to the very high frequency echolocation signals of toothed
whales. There is less information about the existence of corresponding
mechanisms at moderate or low frequencies or in other types of marine
mammals. For example, Zaitseva et al. (1980) found that, for the
bottlenose dolphin, the angular separation between a sound source and a
masking noise source had little effect on the degree of masking when
the sound frequency was 18 kHz, in contrast to the pronounced effect at
higher frequencies. Directional hearing has been demonstrated at
frequencies as low as 0.5-2 kHz in several marine mammals, including
killer whales (Richardson et al., 1995). This ability may be useful in
reducing masking at these frequencies. In summary, high levels of noise
generated by anthropogenic activities may act to mask the detection of
weaker biologically important sounds by some marine mammals. This
masking may be more prominent for lower frequencies. For higher
frequencies, such as that used in echolocation by toothed whales,
several mechanisms are available that may allow them to reduce the
effects of such masking.
In general, NMFS expects the masking effects of seismic pulses to
be minor, given the normally intermittent nature of seismic pulses.
Refer to Appendix B (4) of the draft EA for a more detailed discussion
of masking effects on marine mammals.
Behavioral Disturbance
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). 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).
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
industrial sound. In most cases, this approach likely overestimates the
numbers of marine mammals that would be affected in some biologically-
important manner.
The sound criteria used to estimate how many marine mammals might
be disturbed to some biologically-
[[Page 41469]]
important degree by a seismic program are based primarily on behavioral
observations of a few species. Scientists have conducted detailed
studies on humpback, gray, bowhead, and sperm whales. Less detailed
data are available for some other species of baleen whales, small
toothed whales, and sea otters, but for many species there are no data
on responses to marine seismic surveys.
Baleen Whales--Baleen whales generally tend to avoid operating
airguns, but avoidance radii are quite variable (reviewed in Richardson
et al., 1995). 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, as reviewed in
Appendix B (5) of NSF's EA, 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 4-15 km (2.5-9.3 mi)
from the source. A 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 summarized in Appendix B
(5) of NSF's EA have shown that some species of baleen whales, notably
bowhead and humpback whales, at times, show strong avoidance at
received levels lower than 160 to 170 dB re 1 [mu]Pa (rms).
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 a
source level of 227 dB re 1 [mu]Pa (p-p). In the 1998 study, they
documented that avoidance reactions began at 5-8 km (3.1-5 mi) from the
array, and that those reactions kept most pods approximately 3-4 km
(1.9-2.5 mi) from the operating seismic boat. In the 2000 study,
McCauley et al. (2000a) noted localized displacement during migration
of 4-5 km (2.5-3.1 mi) by traveling pods and 7-12 km (4.3-7.5 mi) 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 for humpback pods containing females, and, at the
mean closest point of approach distance, the received level was 143 dB
re 1 [mu]Pa. The initial avoidance response generally occurred at
distances of 5-8 km (3.1-5 mi) from the airgun array and 2 km (1.2 mi)
from the single airgun. However, some individual humpback whales,
especially males, approached within distances of 100-400 m (328-1,312
ft), where the maximum received level was 179 dB re 1 [mu]Pa.
Data collected by observers during several seismic surveys in the
Northwest Atlantic showed that sighting rates of humpback whales were
significantly greater during periods of no seismic 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 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).
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).
Studies of the bowhead whale show that their responsiveness to
seismic surveys can be quite variable depending on their activity
(migrating vs. feeding). Bowhead whales migrating west across the
Alaskan Beaufort Sea in autumn, in particular, are unusually
responsive, with substantial avoidance occurring out to distances of
20-30 km (12.4-18.6 mi) from a medium-sized airgun source at received
sound levels of around 120 to 130 dB re 1 [mu]Pa (Miller et al., 1999;
Richardson et al., 1999; see Appendix B (5) of NSF's EA). However, more
recent research on bowhead whales (Miller et al., 2005; Harris et al.,
2007) corroborates earlier evidence that, during the summer feeding
season, bowheads are not as sensitive to seismic sources. Nonetheless,
subtle but statistically significant changes in surfacing-respiration-
dive cycles were evident upon statistical analysis (Richardson et al.,
1986). In the summer, bowheads typically begin to show avoidance
reactions at received levels of about 152 to 178 dB re 1 [mu]Pa
(Richardson et al., 1986, 1995; Ljungblad et al., 1988; Miller et al.,
2005).
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% 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% of
feeding whales interrupted feeding at received levels of 163 dB re 1
[mu]Pa. 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
[[Page 41470]]
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). In a study off of Nova Scotia, Moulton and
Miller (2005) found little difference in sighting rates (after
accounting for water depth) and initial sighting distances of
balaenopterid whales when airguns were operating vs. silent. However,
there were indications that these whales were more likely to be moving
away when seen during airgun operations. Similarly, ship-based
monitoring studies of blue, fin, sei and minke whales offshore of
Newfoundland (Orphan Basin and Laurentian Sub-basin) found no more than
small differences in sighting rates and swim directions during seismic
versus non-seismic periods (Moulton et al., 2005, 2006a,b). 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 numbers have increased notably,
despite seismic exploration in their summer and autumn range for many
years (Richardson et al., 1987; Allen and Angliss, 2010).
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 and (in
more detail) in Appendix B of NSF's EA 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 marine mammal observers 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 1 km (0.6 mi) or less, and some individuals show no
apparent avoidance. The beluga whale is a species that (at least at
times) shows long-distance avoidance of seismic vessels. Aerial surveys
conducted in the southeastern Beaufort Sea during summer found that
sighting rates of beluga whales were significantly lower at distances
10-20 km (6.2-12.4 mi) compared with 20-30 km (12.4-18.6 mi) from an
operating airgun array, and observers on seismic boats in that area
rarely saw belugas (Miller et al., 2005; Harris et al., 2007).
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.
Results for porpoises depend on species. The limited available data
suggest that harbor porpoises show stronger avoidance of seismic
operations than do Dall's porpoises (Stone, 2003; MacLean and Koski,
2005; Bain and Williams, 2006; Stone and Tasker, 2006). Dall's
porpoises seem relatively tolerant of airgun operations (MacLean and
Koski, 2005; Bain and Williams, 2006), although they too have been
observed to avoid large arrays of operating airguns (Calambokidis and
Osmek, 1998; Bain and Williams, 2006). This apparent difference in
responsiveness of these two porpoise species is consistent with their
relative responsiveness to boat traffic and some other acoustic sources
(Richardson et al., 1995; Southall et al., 2007).
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 (see Appendix B of NSF's EA for a review). 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 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
[[Page 41471]]
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). However, no beaked whale
species are known to occur in the proposed project area.
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 the
mysticetes, belugas, and harbor porpoises (see Appendix B of NSF's EA
for more information).
Pinnipeds--Pinnipeds are not likely to show a strong avoidance
reaction to the airgun array. Pinnipeds generally seem to be less
responsive to exposure to industrial sound than most cetaceans.
Responses by pinnipeds to underwater sound from some types of
industrial activities such as seismic exploration appear to be
temporary and localized (Harris et al., 2001; Reiser et al., 2009).
Visual monitoring from seismic vessels has shown only slight (if
any) avoidance of airguns by pinnipeds, and only slight (if any)
changes in behavior, see Appendix B(5) of NSF's EA. In the Beaufort
Sea, some ringed seals avoided an area of 100 m (328 ft) to (at most) a
few hundred meters around seismic vessels, but many seals remained
within 100-200 m (328-656 ft) of the trackline as the operating airgun
array passed by (e.g., Harris et al., 2001; Moulton and Lawson, 2002;
Miller et al., 2005). Ringed seal sightings averaged somewhat farther
away from the seismic vessel when the airguns were operating than when
they were not, but the difference was small (Moulton and Lawson, 2002).
Similarly, in Puget Sound, sighting distances for harbor seals and
California sea lions tended to be larger when airguns were operating
(Calambokidis and Osmek, 1998). Previous telemetry work suggests that
avoidance and other behavioral reactions may be stronger than evident
to date from visual studies (Thompson et al., 1998).
Hearing Impairment and Other Physical Effects
Temporary or permanent hearing impairment is a possibility when
marine mammals are exposed to very strong sounds. Non-auditory physical
effects might also occur in marine mammals exposed to strong underwater
sound. Possible types of non-auditory physical effects or injuries that
theoretically might occur in mammals close to a strong sound source
include stress, neurological effects, bubble formation, and other types
of organ or tissue damage. It is possible that some marine mammal
species (i.e., beaked whales) may be especially susceptible to injury
and/or stranding when exposed to strong pulsed sounds. However, as
discussed later in this document, there is no definitive evidence that
any of these effects occur even for marine mammals in close proximity
to industrial sound sources, and beaked whales do not occur in the
proposed activity area.
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. The following subsections discuss in
somewhat more detail the possibilities of TTS, PTS, and non-auditory
physical effects.
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.
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 (found
earlier in this document and Table 1 in UAGI's application) presents
the distances from the Langseth's 10-airgun array at which the received
energy level (per pulse, flat-weighted) would be expected to be greater
than or equal to 180 and 190 dB re 1 [mu]Pa (rms). As shown in the
table, these distances vary with depth.
Researchers have derived TTS information for odontocetes from
studies on the bottlenose dolphin and beluga. For the one harbor
porpoise tested, the received level of airgun sound that elicited onset
of TTS was lower (Lucke et al., 2009). If these results from a single
animal are representative, it is inappropriate to assume that onset of
TTS occurs at similar received levels in all odontocetes (cf. Southall
et al., 2007). Some cetaceans apparently can incur TTS at considerably
lower sound exposures than are necessary to elicit TTS in the beluga or
bottlenose dolphin.
For baleen whales, there are no data, direct or indirect, on levels
or properties of sound that are required to induce TTS. The frequencies
to which baleen whales are most sensitive are assumed to be lower than
those to which odontocetes are most sensitive, and natural background
noise levels at those low frequencies tend to be higher. As a result,
auditory thresholds of baleen whales within their frequency band of
best hearing are believed to be higher (less sensitive) than are those
of odontocetes at their best frequencies (Clark and Ellison, 2004),
meaning that baleen whales require sounds to be louder (i.e., higher dB
levels) than odontocetes in the frequency ranges at which each group
hears the best. From this, it is suspected that received levels causing
TTS onset may also be higher in baleen whales (Southall et al., 2007).
Since current NMFS practice assumes the same thresholds for the onset
of hearing impairment in both odontocetes and mysticetes, NMFS' onset
of TTS threshold is likely conservative for mysticetes. For this
proposed study, UAGI expects no cases of TTS given the strong
likelihood that baleen whales
[[Page 41472]]
would avoid the approaching airguns (or vessel) before being exposed to
levels high enough for TTS to occur.
In pinnipeds, TTS thresholds associated with exposure to brief
pulses (single or multiple) of underwater sound have not been measured.
Initial evidence from more prolonged (non-pulse) exposures suggested
that some pinnipeds (harbor seals in particular) incur TTS at somewhat
lower received levels than do small odontocetes exposed for similar
durations (Kastak et al., 1999, 2005; Ketten et al., 2001). The TTS
threshold for pulsed sounds has been indirectly estimated as being a
sound exposure level (SEL) of approximately 171 dB re 1
[mu]Pa\2\[middot]s (Southall et al., 2007) which would be equivalent to
a single pulse with a received level of approximately 181 to 186 dB re
1 [mu]Pa (rms), or a series of pulses for which the highest rms values
are a few dB lower. Corresponding values for California sea lions and
northern elephant seals are likely to be higher (Kastak et al., 2005).
NMFS has established acoustic thresholds that identify the received
sound levels above which hearing impairment or other injury could
potentially occur, which are 180 and 190 dB re 1 [mu]Pa (rms) for
cetaceans and pinnipeds, respectively (NMFS 1995, 2000). The
established 180- and 190-dB re 1 [mu]Pa (rms) criteria are the received
levels above which, in the view of a panel of bioacoustics specialists
convened by NMFS before additional TTS measurements for marine mammals
became available, one could not be certain that there would be no
injurious effects, auditory or otherwise, to marine mammals. TTS is
considered by NMFS to be a type of Level B (non-injurious) harassment.
The 180- and 190-dB levels are shutdown criteria applicable to
cetaceans and pinnipeds, respectively, as specified by NMFS (2000);
these levels were used to establish the exclusion zones (EZs) described
later in this document.
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 (see Southall et al., 2007),
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. PTS might occur at a received sound level at
least several dB above that inducing mild TTS if the animal were
exposed to strong sound pulses with rapid rise time--see Appendix B (6)
of NSF's EA. 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.
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. Additionally, no beaked whale species occur
in the proposed project area.
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
and some odontocetes, are especially unlikely to incur non-auditory
physical effects.
Stranding and Mortality
Marine mammals close to underwater detonations of high explosives
can be killed or severely injured, and the auditory organs are
especially susceptible to injury (Ketten et al., 1993; Ketten, 1995).
However, explosives are no longer used for marine waters for commercial
seismic surveys or (with rare exceptions) for seismic research; they
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 and, in one case, a L-
DEO seismic survey (Malakoff, 2002; Cox et al., 2006), has raised the
possibility that beaked whales exposed to strong ``pulsed'' sounds may
be especially susceptible to injury and/or behavioral reactions that
can lead to stranding (e.g., Hildebrand, 2005; Southall et al., 2007).
Appendix B (6) of NSF's EA provides additional details.
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
[[Page 41473]]
exposed to sonar. However, the evidence for this remains circumstantial
and is 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 1 kHz. Typical military mid-frequency sonar emits non-
impulse sounds at frequencies of 2-10 kHz, generally with a relatively
narrow bandwidth at any one time. A further difference between seismic
surveys and naval exercises is that naval exercises can involve sound
sources on more than one vessel. Thus, it is not appropriate to assume
that there is a direct connection between the effects of military sonar
and seismic surveys on marine mammals. However, evidence that sonar
signals can, in special circumstances, lead (at least indirectly) to
physical damage and mortality (e.g., Balcomb and Claridge, 2001; NOAA
and USN, 2001; Jepson et al., 2003; Fern[aacute]ndez et al., 2004,
2005; Hildebrand, 2005; Cox et al., 2006) suggests that caution is
warranted when dealing with exposure of marine mammals to any high-
intensity ``pulsed'' sound.
There is no conclusive evidence of cetacean strandings or deaths at
sea as a result of exposure to seismic surveys, but a few cases of
strandings in the general area where a seismic survey was ongoing have
led to speculation concerning a possible link between seismic surveys
and strandings. Suggestions that there was a link between seismic
surveys and strandings of humpback whales in Brazil (Engel et al.,
2004) were not well founded (IAGC, 2004; IWC, 2007). In September 2002,
there was a stranding of two Cuvier's beaked whales in the Gulf of
California, Mexico, when the L-DEO vessel R/V Maurice Ewing was
operating a 20 airgun (8,490 in\3\) array in the general area. The link
between the stranding and the seismic surveys was inconclusive and not
based on any physical evidence (Hogarth, 2002; Yoder, 2002).
Nonetheless, the Gulf of California incident, plus the beaked whale
strandings near naval exercises involving use of mid-frequency sonar,
suggests a need for caution in conducting seismic surveys in areas
occupied by beaked whales until more is known about effects of seismic
surveys on those species (Hildebrand, 2005). No injuries of beaked
whales are anticipated during the proposed study because none occur in
the proposed project area.
Potential Effects on Marine Mammals of Other Acoustic Devices
(1) MBES
UAGI intends to operate the Kongsberg EM 122 MBES from the source
vessel during the proposed study. Sounds from the MBES are very short
pings, occurring for 2-15 ms once every 5-20 s, depending on water
depth. Most of the energy in the sound pulses emitted by this MBES is
at frequencies near 12 kHz, and the maximum source level is 242 dB re 1
[mu]Pa (rms). The beam is narrow (1-2[deg]) in fore-aft extent and wide
(150[deg]) in the cross-track extent. Each ping consists of eight (in
water greater than 1,000 m [3,280 ft] deep) or four (in water less than
1,000 m [3,280 ft] deep) successive fan-shaped transmissions (segments)
at different cross-track angles. Any given mammal at depth near the
trackline would be in the main beam for only one or two of the nine
segments. Also, marine mammals that encounter the Kongsberg EM 122 are
unlikely to be subjected to repeated pulses because of the narrow fore-
aft width of the beam and will receive only limited amounts of pulse
energy because of the short pulses. Animals close to the ship (where
the beam is narrowest) are especially unlikely to be ensonified for
more than one 2-15 ms pulse (or two pulses if in the overlap area).
Similarly, Kremser et al. (2005) noted that the probability of a
cetacean swimming through the area of exposure when a MBES emits a
pulse is small. The animal would have to pass the transducer at close
range and be swimming at speeds similar to the vessel in order to
receive the multiple pulses that might result in sufficient exposure to
cause TTS.
Navy sonars that have been linked to avoidance reactions and
stranding of cetaceans: (1) Generally have longer pulse duration than
the Kongsberg EM 122; and (2) are often directed close to horizontally
versus more downward for the MBES. The area of possible influence of
the MBES is much smaller--a narrow band below the source vessel. Also,
the duration of exposure for a given marine mammal can be much longer
for naval sonar. During operation of this MBES for this proposed
seismic survey, the individual pulses will be very short, and a given
mammal would not receive many of the downward-directed pulses as the
vessel passes by. Possible effects of a MBES on marine mammals are
discussed next.
Masking--Marine mammal communications will not be masked
appreciably by the MBES signals given the low duty cycle of the
echosounder and the brief period when an individual mammal is likely to
be within its beam. Furthermore, in the case of baleen whales, the MBES
signals (12 kHz) do not overlap with the predominant frequencies in the
calls, which would avoid any significant masking.
Behavioral Responses--Behavioral reactions of free-ranging marine
mammals to sonars, echosounders, and other sound sources appear to vary
by species and circumstance. Observed reactions have included silencing
and dispersal by sperm whales (Watkins et al., 1985), increased
vocalizations and no dispersal by pilot whales (Rendell and Gordon,
1999), and the previously-mentioned beachings by beaked whales. During
exposure to a 21-25 kHz ``whale-finding'' sonar with a source level of
215 dB re 1 [mu]Pa, gray whales reacted by orienting slightly away from
the source and being deflected from their course by approximately 200 m
(656 ft) (Frankel, 2005). When a 38 kHz echosounder and a 150 kHz ADCP
were transmitting during studies in the Eastern Tropical Pacific,
baleen whales showed no significant responses, while spotted and
spinner dolphins were detected slightly more often and beaked whales
less often during visual surveys (Gerrodette and Pettis, 2005).
Captive bottlenose dolphins and a beluga whale exhibited changes in
behavior when exposed to 1 s tonal signals at frequencies similar to
those that will be emitted by the MBES used by UAGI and L-DEO (the ship
operator), and to shorter broadband pulsed signals. Behavioral changes
typically involved what appeared to be deliberate attempts to avoid the
sound exposure (Schlundt et al., 2000; Finneran et al., 2002; Finneran
and Schlundt, 2004). The relevance of those data to free-ranging
odontocetes is uncertain, and in any case, the test sounds were quite
different in duration as compared with those from a MBES.
Very few data are available on the reactions of pinnipeds to
echosounder sounds at frequencies similar to those used during seismic
operations. Hastie and Janik (2007) conducted a series of behavioral
response tests on two captive gray seals to determine their reactions
to underwater operation of a 375 kHz multibeam imaging echosounder that
included significant signal components down to 6 kHz. Results indicated
that the two seals reacted to the signal by significantly increasing
their dive durations. Because of the likely brevity of exposure to the
MBES sounds,
[[Page 41474]]
pinniped reactions are expected to be limited to startle or otherwise
brief responses of no lasting consequences to the animals.
Hearing Impairment and Other Physical Effects--Given recent
stranding events that have been associated with the operation of naval
sonar, there is concern that mid-frequency sonar sounds can cause
serious impacts to marine mammals (see above). However, the MBES
proposed for use during UAGI's proposed seismic survey is quite
different than sonar used for Navy operations. Pulse duration of the
MBES is very short relative to the naval sonar. Also, at any given
location, an individual marine mammal would be in the beam of the MBES
for much less time given the generally downward orientation of the beam
and its narrow fore-aft beamwidth; Navy sonar often uses near-
horizontally-directed sound. Those factors would all reduce the sound
energy received from the MBES rather drastically relative to that from
naval sonar. As noted by Burkhardt et al. (2008), cetaceans are very
unlikely to incur PTS from operation of scientific sonars on a ship
that is underway.
NMFS believes that the brief exposure of marine mammals to one
pulse, or small numbers of signals, from the MBES is not likely to
result in the harassment of marine mammals.
(2) SBP
UAGI also intends to operate a SBP from the source vessel during
the proposed survey. Sounds from the SBP are very short pulses,
occurring for 1-4 ms once every second. Most of the energy in the sound
pulses emitted by the SBP is at 3.5 kHz, and the beam is directed
downward. The SBP on the Langseth 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 SBP more powerful than that on the
Langseth--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 SBP 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 SBP
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 SBP are
likely to be similar to those for other pulsed sources if received at
the same levels. However, the pulsed signals from the SBP are
considerably weaker than those from the MBES. 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 SBP 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 SBP is usually operated simultaneously
with other higher-power acoustic sources, including airguns. Many
marine mammals are anticipated to 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 SBP.
(3) ADCP
UAGI intends to operate an ADCP during the proposed seismic survey.
Sounds from the ADCP are very short, occurring every 0.65-1.4 ms. Most
of the energy in the sound emitted is at high frequencies
(approximately 75 kHz). The ADCP produces sounds that are within the
range of frequencies used by odontocetes that may occur in the proposed
project area; however, it is outside the hearing range of mysticetes
and at the extreme upper end of the hearing range for pinnipeds.
Masking--Whereas the ADCP produces sounds within the frequency
range used by odontocetes that may be present in the proposed survey
area, marine mammal communications are not anticipated to be masked
appreciably by the signals. This is a consequence of the relatively low
power output, low duty cycle, and brief period when an individual
mammal is likely to be within the area of potential effects. In the
case of mysticetes and pinnipeds, the pulses do not overlap with the
predominant frequencies in the calls, thus avoiding significant masking
impacts.
Behavioral Responses--When a 38-kHz echosounder and a 150-kHz ADCP
were transmitting during studies in the Eastern Tropical Pacific,
baleen whales showed no significant responses, while spotted and
spinner dolphins were detected slightly more often and beaked whales
less often during visual surveys (Gerrodette and Pettis, 2005). Marine
mammal behavioral reactions to other sound sources are discussed above.
Responses to the ADCP are likely to be similar to those for other
sources if received at the same levels. The signals from the ADCP are
weaker than those from the echosounders and the airguns. Therefore,
behavioral responses are not expected unless marine mammals are very
close to the source.
Hearing Impairment and Other Physical Effects--Source levels of the
ADCP are lower than those of the airguns, which are discussed above. It
is unlikely that the ADCP produces sound levels strong enough to cause
TTS or (especially) PTS or other physical injuries even in marine
mammals that are (briefly) in a position near the source.
The potential effects to marine mammals from the acoustic sources
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
ensure the least practicable impact on affected marine mammal species
and stocks.
Anticipated Effects on 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 reversible 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, previously discussed in this notice. This section
discusses the potential impacts of anthropogenic sound sources on
common marine mammal prey in the proposed survey area (i.e., fish and
invertebrates).
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
populations is limited (see
[[Page 41475]]
Appendix C of NSF's EA). 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 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.
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 (see Appendix C of NSF's EA). 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 UAGI 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 testing) in two of three fish species from
the Mackenzie River Delta. This study found that broad whitefish
(Coregonus nasus) exposed to airgun shots at a SEL of 177 dB re 1
[mu]Pa\2\s showed no hearing loss. 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 9 m [29.5 ft] in the
former case and less than 2 m [6.6 ft] 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).
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 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 (see Appendix C of NSF's EA).
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
[[Page 41476]]
followed by habituation and a return to normal behavior after the sound
ceased.
There is general concern about potential adverse effects of seismic
operations on fisheries, namely a potential reduction in the
``catchability'' of fish involved in fisheries. Although reduced catch
rates have been observed in some marine fisheries during seismic
testing, in a number of cases the findings are confounded by other
sources of disturbance (Dalen and Raknes, 1985; Dalen and Knutsen,
1986; Lokkeborg, 1991; Skalski et al., 1992; Engas et al., 1996). In
other airgun experiments, there was no change in catch per unit effort
of fish when airgun pulses were emitted, particularly in the immediate
vicinity of the seismic survey (Pickett et al., 1994; La Bella et al.,
1996). For some species, reductions in catch may have resulted from a
change in behavior of the fish, e.g., a change in vertical or
horizontal distribution, as reported in Slotte et al. (2004).
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; see also
Appendix D of NSF's EA).
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's EA.
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.
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). 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).
In conclusion, NMFS has preliminarily determined that UAGI's
proposed marine seismic survey is not expected to have any habitat-
related effects that could cause significant or long-term consequences
for individual marine mammals or on the food sources that they utilize.
Proposed Mitigation
In order to issue an incidental take authorization (ITA) under
section 101(a)(5)(D) of the MMPA, NMFS must, where applicable, set
forth the permissible methods of taking pursuant to such activity, and
other means of effecting the least practicable impact on such species
or stock and its habitat,
[[Page 41477]]
paying particular attention to rookeries, mating grounds, and areas of
similar significance, and on the availability of such species or stock
for taking for subsistence uses (where relevant).
UAGI and L-DEO have based the proposed mitigation measures
described herein, to be implemented for the proposed seismic survey, on
the following:
(1) Protocols used during previous L-DEO seismic research cruises
as approved by NMFS; and
(2) 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 proposed activities, UAGI and/or its designees has
proposed to implement the following mitigation measures for marine
mammals:
(1) Proposed exclusion zones;
(2) Power-down procedures;
(3) Shut-down procedures; and
(4) Ramp-up procedures.
Planning Phase
Prior to submitting a final MMPA ITA request to NMFS, NSF works
with the scientists that propose studies to determine when to conduct
the research study. Dr. Coakley worked with L-DEO and NSF to identify
potential time periods to carry out the proposed survey, taking into
consideration key factors such as environmental conditions (i.e., ice
conditions, the seasonal presence of marine mammals and sea birds),
weather conditions, and equipment. The project's proposed timeframe
avoids the eastward (spring) bowhead migration but overlaps with that
of the westward fall migration and the subsistence bowhead hunt along
the north shore of Alaska near Barrow. To avoid disturbance, the
seismic survey has been scheduled to depart from Dutch Harbor in early
September and remain at least 200 km (124 mi) from Barrow during
transit to and from the survey area, which is approximately 250-800 km
(155-497 mi) northwest of Barrow. Also, to reduce potential effects,
the size of the energy source was reduced from the Langseth's 36-
airgun, 6600-in\3\ array to a 10-airgun, 1830-in\3\ array.
Proposed Exclusion Zones
Received sound levels for the 10-airgun array have been predicted
by MAI in relation to distance and direction from the airguns, and
received sound levels for a single 40-in\3\ mitigation airgun have been
predicted by L-DEO. Table 1 shows the distances at which three rms
sound levels are expected to be received from the 10-airgun array and a
single airgun at shallow, intermediate, and deep water depths. The 180-
and 190-dB levels are shut-down criteria applicable to cetaceans and
pinnipeds, respectively, as specified by NMFS (2000); these levels were
used to establish the EZs. For the 10-airgun array, the 180-dB radius
for each of the three water depth categories is as follows: 425 m (0.26
mi) in deep water; 1,400 m (0.87 mi) in intermediate water; and 1,870 m
(1.16 mi) in shallow water. For the 10-airgun array, the 190-dB radius
for each of the three water depth categories is as follows: 130 m
(426.5 ft) in deep water; 130 m (426.5 ft) in intermediate water; and
190 m (623.4 ft) in shallow water. If the protected species visual
observer (PSVO) detects marine mammal(s) within or about to enter the
appropriate EZ, the airguns will be powered down (or shut down if
necessary) immediately (described next).
Power-Down Procedures
A power-down involves decreasing the number of airguns in use such
that the radius of the 180 dB (or 190 dB) zone is decreased to the
extent that marine mammals are no longer in or about to enter the EZ. A
power-down of the airgun array can also occur when the vessel is moving
from one seismic line to another. During a power-down for mitigation,
UAGI and L-DEO will operate one airgun. The continued operation of one
airgun is intended to alert marine mammals to the presence of the
seismic vessel in the area. In contrast, a shut-down occurs when the
Langseth suspends all airgun activity.
If the PSVO detects a marine mammal outside the EZ, but it is
likely to enter the EZ, the airguns will be powered-down before the
animal is within the applicable EZ (dependent upon species). Likewise,
if a marine mammal is already within the EZ when first detected, UAGI
and L-DEO will power-down the airguns immediately. During a power-down
of the airgun array, USGS will also operate the 40 in\3\ airgun. If a
marine mammal is detected within or near the smaller EZ around that
single airgun (Table 1), UAGI and L-DEO will shut-down the airgun (see
next section).
Following a power-down, airgun activity will not resume until the
marine mammal has cleared the EZ. UAGI and L-DEO will consider the
animal to have cleared the EZ if:
A PSVO has visually observed the animal leave the EZ, or
A PSVO has not sighted the animal within the EZ for 15 min
for species with shorter dive durations (i.e., small odontocetes or
pinnipeds), or 30 min for species with longer dive durations (i.e.,
mysticetes; no large odontocetes, such as sperm whales, or beaked
whales occur in the proposed survey area).
The airgun array will be ramped up gradually after the marine
mammal has cleared the EZ (see Ramp-up Procedures).
Shut-Down Procedures
UAGI and L-DEO will shut down the operating airgun(s) if a marine
mammal is seen within or approaching the EZ for the single airgun. A
shut-down shall be implemented:
(1) If an animal enters the EZ of the single airgun after a power-
down has been initiated; or
(2) If an animal is initially seen within the EZ of the single
airgun when more than one airgun (typically the full airgun array) is
operating.
UAGI and L-DEO shall not resume airgun activity until the marine
mammal has cleared the EZ or until the PSVO is confident that the
animal has left the vicinity of the vessel. Criteria for judging that
the animal has cleared the EZ will be as described in the preceding
section regarding a power-down.
Ramp-Up Procedures
UAGI and L-DEO shall follow a ramp-up procedure when the airgun
array begins operating after a specified period without airgun
operations or when a power-down has exceeded that period. UAGI proposes
that, for the present cruise, this period would be approximately 8 min.
L-DEO has used similar periods (approximately 8 to 10 min) during
previous L-DEO surveys.
Ramp-up will begin with the smallest airgun in the array (40
in\3\). Airguns will be added in a sequence such that the source level
of the array will increase in steps not exceeding 6 dB per 5 min period
over a total duration of approximately 15-20 min. During ramp-up, the
PSVOs will monitor the EZ, and if marine mammals are sighted, UAGI and
L-DEO will implement a power-down or shut-down as though the full
airgun array were operational.
If the complete EZ has not been visible for at least 30 min prior
to the start of operations in either daylight or nighttime, ramp-up
shall not commence unless at least one airgun (40 in\3\ or similar) has
been operating during the interruption of seismic survey operations.
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 safety zone for that array will not be visible
during those conditions. If one airgun has operated during a power-down
period, ramp-up to full power will be permissible at
[[Page 41478]]
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. UAGI and L-DEO shall not initiate a
ramp-up of the airguns if a marine mammal is sighted within or near the
applicable EZs during the day or night.
Mitigation Conclusions
NMFS has carefully evaluated the applicant's proposed mitigation
measures and considered a range of other measures in the context of
ensuring that NMFS prescribes the means of effecting the least
practicable impact on the affected marine mammal species and stocks and
their habitat. Our evaluation of potential measures included
consideration of the following factors in relation to one another:
The manner in which, and the degree to which, the
successful implementation of the measure is expected to minimize
adverse impacts to marine mammals;
The proven or likely efficacy of the specific measure to
minimize adverse impacts as planned; and
The practicability of the measure for applicant
implementation.
Based on our evaluation of the applicant's proposed measures, NMFS
has preliminarily determined that the mitigation measures proposed
above provide the means of effecting the least practicable impact on
marine mammal species or stocks and their habitat, paying particular
attention to rookeries, mating grounds, and areas of similar
significance. Proposed measures to ensure availability of such species
or stock for taking for certain subsistence uses is discussed later in
this document (see ``Impact on Availability of Affected Species or
Stock for Taking for Subsistence Uses'' section).
Proposed Monitoring and Reporting
In order to issue an ITA for an activity, section 101(a)(5)(A) of
the MMPA states that NMFS must, where applicable, set forth
``requirements pertaining to the monitoring and reporting of such
taking.'' The MMPA implementing regulations at 50 CFR 216.104 (a)(13)
indicate that requests for ITAs must include the suggested means of
accomplishing the necessary monitoring and reporting that will result
in increased knowledge of the species and of the level of taking or
impacts on populations of marine mammals that are expected to be
present in the proposed action area.
UAGI proposes 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 (if issued). UAGI's
proposed Monitoring Plan is described next. UAGI understands that this
monitoring plan will be subject to review by NMFS (as well as the
public), 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. UAGI is prepared to discuss
coordination of its monitoring program with any related work that might
be done by other groups insofar as this is practical and desirable.
Vessel-Based Visual Monitoring
PSVOs 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 at night. PSVOs will also watch for marine mammals
near the seismic vessel for at least 30 min prior to the start of
airgun operations after an extended shut-down (as described in the
``Proposed Mitigation'' section earlier in this document). PSVOs 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
PSVO observations, the airguns will be powered-down or shut-down when
marine mammals are observed within or about to enter a designated EZ.
During seismic operations in the Arctic Ocean, at least five PSOs
will be based aboard the Langseth. L-DEO will appoint the PSOs with
NMFS' concurrence. Observations will take place during ongoing daytime
operations and nighttime ramp-ups of the airguns. During the majority
of seismic operations, two PSVOs will be on duty from the observation
tower to monitor marine mammals near the seismic vessel. Use of two
simultaneous PSVOs will increase the effectiveness of detecting animals
near the source vessel. However, during meal times and bathroom breaks,
it is sometimes difficult to have two PSVOs on effort, but at least one
PSVO will be on duty. PSVO(s) will be on duty in shifts of duration no
longer than 4 hr.
Two PSVOs will also be on visual watch during all nighttime ramp-
ups of the seismic airguns. A third PSO will monitor the passive
acoustic monitoring (PAM) equipment 24 hours a day to detect vocalizing
marine mammals present in the action area. In summary, a typical
daytime cruise would have scheduled two PSVOs on duty from the
observation tower, and a third PSO on PAM. 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 Langseth is a suitable platform for marine mammal observations.
When stationed on the observation platform, the eye level will be
approximately 21.5 m (70.5 ft) above sea level, and the PSVO will have
a good view around the entire vessel. During daytime, the PSVOs will
scan the area around the vessel systematically with reticle binoculars
(e.g., 7 x 50 Fujinon), Big-eye binoculars (25 x 150), and with the
naked eye. During darkness, night vision devices (NVDs) will be
available (ITT F500 Series Generation 3 binocular-image intensifier or
equivalent), when required. Laser range-finding binoculars (Leica LRF
1200 laser rangefinder or equivalent) will be available to assist with
distance estimation. Those are useful in training observers to estimate
distances visually, but are generally not useful in measuring distances
to animals directly; that is done primarily with the reticles in the
binoculars.
When marine mammals are detected within or about to enter the
designated EZ, the airguns will immediately be powered-down or shut-
down if necessary. The PSO(s) will continue to maintain watch to
determine when the animal(s) are outside the EZ by visual confirmation.
Airgun operations will not resume until the animal is confirmed to have
left the EZ, or if not observed after 15 min for species with shorter
dive durations (small odontocetes and pinnipeds) or 30 min for species
with longer dive durations (mysticetes).
Passive Acoustic Monitoring (PAM)
PAM will complement the visual monitoring program, when
practicable. Visual monitoring typically is not effective during
periods of poor visibility or at night, and even with good visibility,
is unable to detect marine mammals when they are below the surface or
beyond visual range.
Besides the three PSVOs, an additional Protected Species Acoustic
Observer (PSAO) with primary responsibility for PAM will also be aboard
the vessel. UAGI and L-DEO can use acoustic monitoring in addition to
visual observations to improve detection, identification, and
localization of marine mammals. The
[[Page 41479]]
acoustic monitoring will serve to alert visual observers (if on duty)
when vocalizing marine mammals are detected. It is only useful when
marine mammals call, but it can be effective either by day or by night
and does not depend on good visibility. It will be monitored in real
time so that the PSVOs can be advised when animals are detected
acoustically. When bearings (primary and mirror-image) to calling
animal(s) are determined, the bearings will be relayed to the visual
observer to help him/her sight the calling animal(s).
The PAM system consists of hardware (i.e., hydrophones) and
software. The ``wet end'' of the system consists of a towed hydrophone
array that is connected to the vessel by a tow cable. The array will be
deployed from a winch located on the back deck. A deck cable will
connect from the winch to the main computer laboratory where the
acoustic station and signal conditioning and processing system will be
located. The digitized signal and PAM system is monitored by PSAOs at a
station in the main laboratory. The hydrophone array is typically towed
at depths of less than 20 m (66 ft).
Ideally, the PSAO will monitor the towed hydrophones 24 hr per day
at the seismic survey area during airgun operations and during most
periods when the Langseth is underway while the airguns are not
operating. However, PAM may not be possible if damage occurs to both
the primary and back-up hydrophone arrays during operations. The
primary PAM streamer on the Langseth is a digital hydrophone streamer.
Should the digital streamer fail, back-up systems should include an
analog spare streamer and a hull-mounted hydrophone. Every effort would
be made to have a working PAM system during the cruise. In the unlikely
event that all three of these systems were to fail, UAGI would continue
science acquisition with the visual-based observer program. The PAM
system is a supplementary enhancement to the visual monitoring program.
If weather conditions were to prevent the use of PAM, then conditions
would also likely prevent the use of the airgun array.
One PSAO will monitor the acoustic detection system at any one
time, by listening to the signals from two channels via headphones and/
or speakers and watching the real-time spectrographic display for
frequency ranges produced by marine mammals. PSAOs monitoring the
acoustical data will be on shift for 1-6 hours at a time. Besides the
PSVO, an additional PSAO with primary responsibility for PAM will also
be aboard the source vessel. All PSVOs are expected to rotate through
the PAM position, although the most experienced with acoustics will be
on PAM duty more frequently.
When a vocalization is detected while visual observations are in
progress, the PSAO will contact the PSVO immediately, to alert him/her
to the presence of marine mammals (if they have not already been seen),
and to allow a power-down or shut-down to be initiated, if required.
The information regarding the call will be entered into a database.
Data entry will include an acoustic encounter identification number,
whether it was linked with a visual sighting, date, time when first and
last heard and whenever any additional information was recorded,
position and water depth when first detected, bearing if determinable,
species or species group (e.g., unidentified dolphin, sperm whale),
types and nature of sounds heard (e.g., clicks, continuous, sporadic,
whistles, creaks, burst pulses, strength of signal, etc.), and any
other notable information. The acoustic detection can also be recorded
for further analysis.
PSVO Data and Documentation
PSVOs 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 power-down
or shut-down of the airguns when a marine mammal is within or near the
EZ. Observations will also be made during daytime periods when the
Langseth is underway without seismic operations.
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 airguns or vessel (e.g., none, avoidance,
approach, paralleling, etc.), and behavioral pace.
2. Time, location, heading, speed, activity of the vessel, sea
state, 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 and power-downs or shut-downs will be recorded in
a standardized format. Data will be entered into an electronic
database. The accuracy of the data entry will be verified by
computerized data validity checks as the data are entered and by
subsequent manual checking of the database. These procedures will allow
initial summaries of data to be prepared during and shortly after the
field program and will facilitate transfer of the data to statistical,
graphical, and other programs for further processing and archiving.
Results from the vessel-based observations will provide:
1. The basis for real-time mitigation (airgun power-down or 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.
UAGI will submit a report to NMFS and NSF 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 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 (dates, times, locations, activities, associated
seismic survey activities). 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.
In the unanticipated event that the specified activity clearly
causes the take of a marine mammal in a manner prohibited by the IHA
(if issued), such as an injury (Level A harassment), serious injury or
mortality (e.g., ship-strike, gear interaction, and/or entanglement),
UAGI and L-DEO will immediately cease the specified activities and
immediately report the incident to the Chief of the Permits,
Conservation, and Education Division, Office of Protected Resources,
NMFS, and the Alaska Regional Stranding Coordinators. The report must
include the following information:
Time, date, and location (latitude/longitude) of the
incident;
Name and type of vessel involved;
[[Page 41480]]
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 will not resume until NMFS is able to review the
circumstances of the prohibited take. NMFS will work with UAGI to
determine what is necessary to minimize the likelihood of further
prohibited take and ensure MMPA compliance. UAGI may not resume their
activities until notified by NMFS via letter, e-mail, or telephone.
In the event that UAGI 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),
UAGI will immediately report the incident to the Chief of the Permits,
Conservation, and Education Division, Office of Protected Resources,
NMFS, and the NMFS Alaska Stranding Hotline and/or by e-mail to the
Alaska Regional Stranding Coordinators. 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 UAGI to determine whether modifications in the
activities are appropriate.
In the event that UAGI discovers an injured or dead marine mammal,
and the lead PSO determines that the injury or death is not associated
with or related to the activities authorized in the IHA (e.g.,
previously wounded animal, carcass with moderate to advanced
decomposition, or scavenger damage), UAGI will report the incident to
the Chief of the Permits, Conservation, and Education Division, Office
of Protected Resources, NMFS, and the NMFS Alaska Stranding Hotline
and/or by e-mail to the Alaska Regional Stranding Coordinators, within
24 hours of the discovery. UAGI will provide photographs or video
footage (if available) or other documentation of the stranded animal
sighting to NMFS and the Marine Mammal Stranding Network.
Estimated Take by Incidental Harassment
Except with respect to certain activities not pertinent here, the
MMPA defines ``harassment'' as: ``any act of pursuit, torment, or
annoyance which (i) Has the potential to injure a marine mammal or
marine mammal stock in the wild [Level A harassment]; or (ii) has the
potential to disturb a marine mammal or marine mammal stock in the wild
by causing disruption of behavioral patterns, including, but not
limited to, migration, breathing, nursing, breeding, feeding, or
sheltering [Level B harassment].'' Only take by Level B harassment is
anticipated and proposed to be authorized as a result of the proposed
marine seismic survey in the Arctic Ocean. Acoustic stimuli (i.e.,
increased underwater sound) generated during the operation of the
seismic airgun array may have the potential to cause marine mammals in
the survey area to be exposed to sounds at or greater than 160 dB or
cause temporary, short-term changes in behavior. NMFS also assumes that
marine mammals exposed to levels exceeding 160 dB re 1 [mu]Pa (rms) may
experience Level B harassment. The use of the ADCP is not anticipated
to result in the take of low-frequency cetaceans or pinnipeds, as the
frequency for this device is outside of or at the extreme upper end of
the hearing ranges of these species. There is no evidence that the
planned activities could result in injury, serious injury, or mortality
within the specified geographic area for which UAGI seeks the IHA. The
proposed mitigation and monitoring measures will minimize any potential
risk for injury, serious injury, or mortality.
The following sections describe UAGI'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. The estimates are based on a consideration of the
number of marine mammals that could be disturbed appreciably by
operations with the 10-airgun array to be used during approximately
5,500 km (3,417.5 mi) of survey lines in the Arctic Ocean.
The anticipated radii of influence of the MBES, SBP, and ADCP are
less than those for the airgun array. UAGI assumes that, during
simultaneous operations of the airgun array and the other sources, any
marine mammals close enough to be affected by the MBES, SBP, and ADCP
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 MBES, SBP, and ADCP given their
characteristics (e.g., narrow, downward-directed beam) and other
considerations described previously. Therefore, UAGI provides no
additional allowance for animals that could be affected by sound
sources other than airguns.
UAGI calculated densities using data from the Chukchi Sea for the
fall in depth strata 35-50 m (115-164 ft), 51-200 m (167-656 ft), and
greater than 200 m (656 ft), mean group sizes from the Beaufort Whale
Aerial Survey Project (BWASP) database, and values for trackline
detection probability bias and availability bias, f(0) and g(0), from
Harwood et al. (1996) for belugas, Thomas et al. (2002) for bowhead
whales, and Forney and Barlow (1998) for gray whales. Based on the lack
of any beluga whale sightings and very low densities of bowheads
(0.0003-0.0044/km \2\) and gray whales (0.0026-0.0042/km \2\) during
non-seismic periods of industry vessel operations in the Chukchi Sea in
September-October 2006-2008 (Haley et al. 2010), and the lack of
beluga, bowhead, or gray whale sightings during arctic cruises by the
Healy in August-September 2005 or July-August 2006 (Haley 2006; Haley
and Ireland 2006), the calculated densities are possibly overestimates.
Accordingly, they were reduced by an order of magnitude. Densities were
calculated for depths greater than 200 m (656 ft) and less than 200 m
(656 ft); in the latter case, the densities were effort-weighted
averages of the 35-50 m (115-164 ft) and 51-200 m (167-656 ft)
densities.
There is evidence of the occasional occurrence of humpback, minke,
fin, and killer whales in the northern Chukchi Sea, but because they
occur so infrequently in the Chukchi Sea, little to no data are
available for the calculation of densities. Minimal densities have
therefore been assigned to these species to allow for chance
encounters.
Four species of pinnipeds under NMFS jurisdiction could be
encountered in the proposed seismic survey area: ringed seal, bearded
seal, ribbon seal, and spotted seal. Bengtson et al. (2005) reported
ringed and bearded seal densities in nearshore fast ice and pack ice
and offshore pack ice based on aerial surveys in May-June 1999 and May
2000; ringed seal but not bearded seal densities were corrected for
haulout behavior. UAGI used densities from the offshore stratum (12P).
Bearded seal densities were used for water depths less than 200 m (656
ft) and were assumed to be zero in water
[[Page 41481]]
depths greater than 200 m (656 ft) because they are predominantly
benthic feeders. The fall densities of ringed seals in the open water
of the offshore survey area have been estimated as 1/10 of the spring
pack ice densities because ringed seals are strongly associated with
sea ice and begin to reoccupy nearshore fast ice areas as it forms in
the fall. The resulting densities (.081/km \2\ in 1999 and .023/km \2\
in 2000) are similar to ringed seal density estimates (0.016/km \2\ to
0.069/km \2\) from industry vessel operations during summer 2006-2008
(Haley et al., 2010).
Little information is available on spotted seal or ribbon seal
densities in offshore areas of the Chukchi Sea. Spotted seal density in
the summer was estimated by multiplying the ringed seal density by
0.02. This calculation was based on the ratio of the estimated Chukchi
populations of the two species: 8% of the Alaskan population of spotted
seals is present in the Chukchi Sea during the summer and fall (Rugh et
al., 1997); the Alaskan population of spotted seals is 59,214 (Allen
and Angliss, 2010); and the population of ringed seals in the Alaskan
Chukchi Sea is greater than 208,000 (Bengtson et al., 2005). The ribbon
seal density used is based on two ribbon seal sightings reported during
industry vessel operations in the Chukchi Sea in 2006-2008 (Haley et
al., 2010).
Table 2 in this document (and Table 3 in UAGI's application)
provides the estimated densities of marine mammals expected to occur in
the proposed survey area. As noted previously, there is some
uncertainty about the representativeness of the data and assumptions
used in the calculations. Because few data were available for the
survey area, UAGI calculated densities based on densities observed in
adjacent areas of the northern Chukchi Sea, adjusted downward by
various assumed factors (see above and UAGI's application). For species
seen only rarely in the northern Chukchi Sea, UAGI assigned low
densities. It is not known how closely the densities that were used
reflect the actual densities that will be encountered; however, the
approach used here is believed to be the best available at this time.
The estimated numbers of individuals potentially exposed are presented
below based on the 160-dB re 1 [mu]Parms criterion for all marine
mammals.
Table 2--Expected Densities of Marine Mammals in the Offshore Survey
Area of the Arctic Ocean North of the Chukchi Sea in September-October
2011. Cetacean Densities are Corrected for f(0) and g(0) Biases. Species
Listed as Endangered are in Italics
------------------------------------------------------------------------
Density (/1000 km \2\) i>/1000 km \2\)
Species in depths <200 m in depths >200 m
------------------------------------------------------------------------
Mysticetes:
Bowhead Whale................. 1.87 0
Gray Whale.................... 1.48 0
Fin Whale..................... 0.01 0.01
Humpback Whale................ 0.01 0.01
Minke Whale................... 0.01 0.01
Odontocetes:
Beluga........................ 1.65 6.78
Killer whale.................. 0.01 0.01
Pinnipeds:
Bearded Seal.................. 14.18 0
Spotted Seal.................. 0.98 0.98
Ringed Seal................... 48.92 48.92
Ribbon Seal................... 0.27 0.27
------------------------------------------------------------------------
UAGI's estimates of exposures to various sound levels assume that
the proposed survey will be fully completed; in fact, the ensonified
areas calculated using the planned number of line-kilometers have been
increased by 25% to accommodate turns, lines that may need to be
repeated, equipment testing, 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 Langseth is not ice-
strengthened and will completely avoid ice, so it is very likely that
the survey will not be completed because ice likely will be present.
Furthermore, any marine mammal sightings within or near the designated
EZ will result in the shut-down of seismic operations as a mitigation
measure. Thus, the following estimates of the numbers of marine mammals
potentially exposed to 160 dB (rms) sounds are precautionary, and
probably overestimate the actual numbers of marine mammals that might
be involved. These estimates assume that there will be no ice, weather,
equipment, or mitigation delays, which is highly unlikely.
UAGI 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. The number of possible exposures (including
repeated 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, including areas of overlap. In the
proposed survey, the seismic lines are widely spaced in the survey
area, so few individual marine mammals would be exposed more than once
during the survey. The area including overlap is only 1.3 times the
area excluding overlap. Moreover, 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 [micro]Pa (rms) was calculated by
multiplying:
(1) The expected species density, times.
(2) The anticipated area to be ensonified to that level during
airgun operations in each depth stratum, 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
[[Page 41482]]
``drawing'' the applicable 160 dB buffer (see Table 1 in this document
and in the IHA application) around each seismic line, and then
calculating the total area within the buffers. Areas of overlap
(because of lines being closer together than the 160 dB radius) were
limited and included only once when estimating the number of
individuals exposed. Before calculating numbers of individuals exposed,
the areas were increased by 25% as a precautionary measure.
For species whose densities were the same regardless of water
depth, UAGI used ensonified areas for all water depths to calculate
numbers exposed. For species whose densities were different in water
depths less than 200 m (656 ft) and greater than 200 m (656 ft; see
Table 2 in this document and Table 3 in UAGI's application), UAGI used
ensonified areas for tracklines in water depths less than 200 m (656
ft) and the sum of the ensonified areas in water depths 200-1,000 m
(656-3,280 ft) and greater than 1,000 m (3,280 ft) and applied them to
the different densities.
Table 4 in UAGI's application shows the estimates of the number of
different individual marine mammals that potentially could be exposed
to sounds greater than or equal to 160 dB re 1 [mu]Pa (rms) during the
proposed seismic survey if no animals moved away from the survey
vessel. Table 3 in this document presents the abundance of the
different species or stocks, proposed take authorization, and the
percentage of the regional population or stock. Table 4 in UAGI's
application includes species beyond those presented in Table 3 in this
document for which take is requested. Walrus and polar bears are not
included in this document because those species are under the
jurisdiction of the USFWS. Although presented in Table 4 in UAGI's
application, no take has been requested and none is proposed to be
authorized for narwhal or harbor porpoise. Because the harbor porpoise
is mainly a shallow-water species, it is not expected to occur in the
survey area. Narwhals are considered extralimital in Alaska, and any
vagrants likely would be associated with sea ice. The Langseth is not
ice-strengthened and will completely avoid ice, so encounters with
narwhals are not expected.
Applying the approach described above, approximately 122,530 km\2\
(47,309 mi\2\; approximately 153,163 km\2\ [59,137 mi\2\] including the
25% contingency) would be within the 160-dB isopleth on one or more
occasions during the survey. For less than 200 m (656 ft) and greater
than 200 m (656 ft) depth ranges, the areas are 38,188 km\2\ (14,744
mi\2\; 47,736 km\2\ [18,431 mi\2\] including the 25% contingency) and
84,342 km\2\ (32,565 mi\2\; 105,427 km\2\ [40,706 mi\2\] including the
25% contingency), respectively. Because this approach does not allow
for turnover in the mammal populations in the study area during the
course of the survey, the actual number of individuals exposed could be
underestimated in some cases. However, the approach assumes that no
marine mammals will move away from or toward the trackline as the
Langseth approaches in response to increasing sound levels prior to the
time the levels reach 160 dB, which will result in overestimates for
those species known to avoid seismic vessels. The take estimates
presented in this section of the document do not take into
consideration the mitigation and monitoring measures that are proposed
for inclusion in the IHA (if issued).
Table 3--Population Abundance Estimates, Total Proposed Take, and the Percentage of the Population or Stock That
May Be Exposed to Sounds >=160 db re 1 [mu]Pa (rms) During the Proposed Seismic Survey in the Arctic Ocean,
September-October 2011
----------------------------------------------------------------------------------------------------------------
Percentage of
Species Abundance \1\ Proposed take population or
authorization stock
----------------------------------------------------------------------------------------------------------------
Bowhead Whale....................................... \2\ 14,731 89 0.6
Gray Whale.......................................... 19,126 71 0.4
Humpback Whale...................................... \3\ 20,800 2 0.01
Minke Whale......................................... 810 2 0.2
Fin Whale........................................... 5,700 2 0.04
Beluga Whale........................................ \4\ 42,968 794 1.8
Killer Whale........................................ \5\ 768 2 0.3
Bearded Seal........................................ 250,000-300,000 677 0.2-0.3
Spotted Seal........................................ 59,214 150 0.3
Ringed Seal......................................... 249,000 7,492 3
Ribbon Seal......................................... 49,000 42 0.09
----------------------------------------------------------------------------------------------------------------
\1\ Unless stated otherwise, abundance estimates are from Allen and Angliss (2011).
\2\ Based on estimate of 10,545 individuals in 2001 with a 3.4% annual growth rate (George et al., 2004 and
revised by Zeh and Punt, 2005).
\3\ North Pacific Ocean (Barlow et al., 2009).
\4\ Based on estimates for the eastern Chukchi Sea and Beaufort Sea stocks (Allen and Angliss, 2011).
\5\ Based on estimates for the Northern resident and transient stocks (Allen and Angliss, 2011).
Encouraging and Coordinating Research
UAGI and NSF will coordinate the planned marine mammal monitoring
program associated with the seismic survey in the Arctic Ocean with
other parties that may have interest in the area and/or be conducting
marine mammal studies in the same region during the proposed seismic
survey. No other marine mammal studies are expected to occur in the
study area at the proposed time. However, other industry-funded seismic
surveys may be occurring in the northeast Chukchi and/or western
Beaufort Sea closer to shore, and those projects are likely to involve
marine mammal monitoring. UAGI and NSF have coordinated, and will
continue to coordinate, with other applicable Federal, State, and
Borough agencies, and will comply with their requirements.
Negligible Impact and Small Numbers Analysis and Preliminary
Determination
NMFS has defined ``negligible impact'' in 50 CFR 216.103 as ``* * *
an impact resulting from the specified activity that cannot be
reasonably expected to, and is not reasonably likely to, adversely
affect the species or stock through effects on annual rates of
recruitment or survival.'' In making a negligible impact determination,
NMFS considers a variety of factors, including
[[Page 41483]]
but not limited to: (1) The number of anticipated mortalities; (2) the
number and nature of anticipated injuries; (3) the number, nature,
intensity, and duration of Level B harassment; and (4) the context in
which the takes occur.
For reasons stated previously in this document, no injuries or
mortalities are anticipated to occur as a result of UAGI's proposed
seismic survey, and none are proposed to be authorized by NMFS.
Additionally, for reasons presented earlier in this document, temporary
hearing impairment (and especially permanent hearing impairment) is not
anticipated to occur during the proposed specified activity. Impacts to
marine mammals are anticipated to be in the form of Level B behavioral
harassment only, due to the brief duration and sporadic nature of the
survey. Certain species may have a behavioral reaction (e.g., increased
swim speed, avoidance of the area, etc.) to the sound emitted during
the proposed marine seismic survey. Table 3 in this document outlines
the number of Level B harassment takes that are anticipated as a result
of the proposed activities. No mortality or injury is expected to
occur, and due to the nature, degree, and context of behavioral
harassment anticipated, the activity is not expected to impact rates of
recruitment or survival. The proposed survey would not occur in any
areas designated as critical habitat for ESA-listed species.
Additionally, as mentioned previously in this document, the proposed
seismic survey will not destroy marine mammal habitat.
While some of the species could potentially occur in the proposed
survey area year-round, some species only occur at certain times of the
year. In the fall, bowhead whales begin their westward migration
through the Beaufort Sea in late August/early September. The whales
usually reach Barrow around mid-September. It is likely that most
bowhead whales will not enter the proposed survey area until about the
second half of the proposed survey time period. Additionally, humpback
and fin whales have only started to be sighted in the Chukchi Sea in
the last 5-6 years. As the extent of Arctic sea ice begins to change,
these species may be expanding their normal range further north.
However, this is still considered the extreme northern edge of the
range of these species, so it is unlikely that they will be present
throughout the entire proposed survey time period.
Of the 11 marine mammal species likely to occur in the proposed
survey area, three are listed as endangered under the ESA: Bowhead,
humpback, and fin whale. All of these species are also considered
depleted under the MMPA. As stated previously in this document, the
affected bowhead whale stock has been increasing at a rate of 3.4% per
year since 2001. On December 10, 2010, NMFS published a notification of
proposed threatened status for subspecies of the ringed seal (75 FR
77476) and a notification of proposed threatened and not warranted
status for subspecies and distinct population segments of the bearded
seal (75 FR 77496) in the Federal Register. Neither species is
considered depleted under the MMPA. The listing for these species is
not anticipated to be completed prior to the end of this proposed
seismic survey. Certain stocks of beluga whale and spotted seal are
listed or proposed for listing under the ESA. However, those stocks do
not occur in the proposed project area.
As has been noted previously in this document, many cetacean
species, especially mysticetes, may display avoidance reactions and not
enter into areas close to the active airgun array. However, alternate
areas are available to these species. The location of the survey is not
a known feeding ground for these species. It is not used for breeding
or nursing. Although ice seals breed and nurse in the Chukchi Sea, the
survey occurs outside of the time for ice seal breeding or nursing in
the Chukchi Sea.
The population estimates for the species that may potentially be
taken as a result of UAGI's proposed seismic survey were presented
earlier in this document. For reasons described earlier in this
document, the maximum calculated number of individual marine mammals
for each species that could potentially be taken by harassment is small
relative to the overall population sizes (3% for ringed seals, 1.8% for
beluga whales, and less than 1% of each of the other 9 marine mammal
populations or stocks).
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the mitigation and monitoring
measures, NMFS preliminarily finds that the proposed seismic survey
will result in the incidental take of small numbers of marine mammals
and that the total taking from UAGI's proposed activities will have a
negligible impact on the affected species or stocks. Impact on
Availability of Affected Species or Stock for Taking for Subsistence
Uses
Relevant Subsistence Uses
Subsistence remains the basis for Alaska Native culture and
community. Marine mammals are legally hunted in Alaskan waters by
coastal Alaska Natives. In rural Alaska, subsistence activities are
often central to many aspects of human existence, including patterns of
family life, artistic expression, and community religious and
celebratory activities. Additionally, the animals taken for subsistence
provide a significant portion of the food that will last the community
throughout the year. The main species that are hunted include bowhead
and beluga whales, ringed, spotted, and bearded seals, walruses, and
polar bears. (As mentioned previously in this document, both the walrus
and the polar bear are under the USFWS' jurisdiction.) The importance
of each of these species varies among the communities and is largely
based on availability.
Barrow and Wainwright, which is in the Chukchi Sea, are the two
villages that are closest to the proposed survey area, which will be
initiated more than 200 km (124 mi) offshore. Marine mammals are also
hunted in the Beaufort Sea villages of Kaktovik and Nuiqsut (mostly
from Cross Island). Other villages in the Chukchi Sea that hunt for
marine mammals include Point Lay, Point Hope, Kivalina, and Kotzebue.
The villages of Kivalina and Kotzebue are many hundreds of miles south
of the proposed project area.
(1) Bowhead Whale
Bowhead whale hunting is the key activity in the subsistence
economies of Barrow and two smaller communities to the east, Nuiqsut
and Kaktovik. Bowhead whales are also hunted by communities along the
Chukchi Sea. The community of Barrow hunts bowhead whales in both the
spring and fall during the whales' seasonal migrations along the coast.
The communities of Nuiqsut and Kaktovik participate only in the fall
bowhead harvest. The spring hunt at Barrow occurs after leads open
because of the deterioration of pack ice; the spring hunt typically
occurs from early April until the first week of June. The fall
migration of bowhead whales that summer in the eastern Beaufort Sea
typically begins in late August or September. The location of the fall
subsistence hunt depends on ice conditions and (in some years)
industrial activities that influence the bowheads movements as they
move west (Brower, 1996). In the fall,
[[Page 41484]]
subsistence hunters use aluminum or fiberglass boats with outboards.
Hunters prefer to take bowheads close to shore to avoid a long tow
during which the meat can spoil, but Braund and Moorehead (1995) report
that crews may (rarely) pursue whales as far as 80 km (50 mi) offshore.
The autumn hunt at Barrow usually begins in mid-September, and mainly
occurs in the waters east and northeast of Point Barrow. The whales
have usually left the Beaufort Sea by late October (Treacy, 2002a,b).
Along the Chukchi Sea coast, bowhead whales have recently primarily
been hunted during the spring, between March and June. However, with
changing ice patterns, there is a possibility that Chukchi Sea villages
could begin participating in fall bowhead whale hunts. Table 4 in this
document (Table 5 in UAGI's application) presents harvest data for the
years 1993-2008 for bowhead whale hunts in five North Slope
communities.
The proposed survey will not have any impacts on the spring bowhead
whale hunt by communities along the Chukchi Sea and Barrow, as those
hunts are completed many months prior to the beginning of this proposed
survey. The villages of Kaktovik and Nuiqsut are several hundred miles
to the east of the proposed survey location. Therefore, no impacts are
anticipated on the fall hunts at Kaktovik or Nuiqsut (Cross Island).
The closest tracklines to Barrow are more than 200 km (124 mi) and in
most cases between 250 and 800 km (155-497 mi) to the northwest of
Barrow. The whales will reach Barrow before they enter into the
proposed survey area.
[GRAPHIC] [TIFF OMITTED] TN14JY11.002
(2) Beluga Whale
Beluga whales are available to subsistence hunters at Barrow in the
spring when pack-ice conditions deteriorate and leads open up. Belugas
may remain in the area through June and sometimes into July and August
in ice-free waters. Hunters usually wait until after the spring bowhead
whale hunt is finished before turning their attention to hunting
belugas. Few, if any, belugas are taken by Kaktovik and Nuiqsut hunters
and only during the fall whale harvest. Along the Chukchi Sea, belugas
are hunted during the spring and in the summer (between July and
August) by residents of Wainwright and Point Hope. Near Point Lay,
belugas are taken in June and July. During 2002-2006, Alaska Native
subsistence hunters took a mean annual number of 25.4 beluga whales
from the Beaufort Sea stock and 59 from the eastern Chukchi Sea stock.
The average annual harvest of beluga whales taken by Barrow for 1962-
1982 was five (MMS, 1996). The Alaska Beluga Whale Committee recorded
that 23 beluga whales had been harvested by Barrow hunters from 1987 to
2002, ranging from 0 in 1987, 1988, and 1995 to the high of 8 in 1997
(Fuller and George, 1999; Alaska Beluga Whale Committee, 2002 cited in
USDI/BLM, 2005).
UAGI's proposed seismic survey is not anticipated to impact beluga
hunts conducted by villages of the North Slope. The timing of the
proposed survey is after the spring and summer beluga harvests in the
Chukchi Sea. Although hunting of beluga from Point Hope may extend into
September, off Point Hope, the vessel will remain approximately 80 km
(50 mi) from the coast, in transit northward to the study area.
(3) Ice Seals
Ringed seals are hunted by villagers along the Beaufort Sea coast
mainly from October through June. Hunting for these smaller mammals is
concentrated during winter because bowhead whales, bearded seals, and
caribou are available through other seasons. Winter leads in the area
off Point Barrow and along the barrier islands of Elson Lagoon to the
east are used for hunting ringed seals. The average annual ringed seal
harvest by the community of Barrow from the 1960s through much of the
1980s has been estimated as 394. Along the Chukchi Sea coast, ringed
seals are
[[Page 41485]]
mainly taken between May and September near Wainwright, and throughout
the year by Point Lay and Point Hope hunters. As the seismic survey
will occur far offshore, the survey will not affect ringed seals in the
nearshore areas where they are hunted. It is unlikely that
accessibility to ringed seals during the subsistence hunt could be
impaired during the Langseth's transit to and from the study area when
the airguns are not operating. Although some hunting in the Chukchi Sea
does occur as far as 32 km (20 mi) from shore, the area affected during
transit would be in close proximity to the ship, which will be
transiting approximately 80 km (50 mi) offshore.
The spotted seal subsistence hunt on the Beaufort Sea coast peaks
in July and August, at least in 1987-1990, but involves few animals.
Spotted seals typically migrate south by October to overwinter in the
Bering Sea. Admiralty Bay, less than 60 km (37 mi) to the east of
Barrow (and more than 260 km [162 mi] from the proposed survey area),
is a location where spotted seals are harvested. Spotted seals are also
occasionally hunted in the area off Point Barrow and along the barrier
islands of Elson Lagoon to the east (USDI/BLM, 2005). The average
annual spotted seal harvest by the community of Barrow from 1987-1990
was one (Braund et al., 1993). Along the Chukchi Sea coast, seals are
mainly taken between May and September near Wainwright, and throughout
the year by Point Lay and Point Hope hunters.
The proposed seismic survey will take place at least 200 km
offshore from the preferred nearshore harvest area of these seals. It
is unlikely that accessibility to spotted seals during the subsistence
hunt could be impaired during the Langseth's transit to and from the
study area when the airguns are not operating. Although some hunting in
the Chukchi Sea does occur as far as 40 km (25 mi) from shore, the area
affected during transit would be in close proximity to the ship.
Bearded seals, although not favored for their meat, are important
to subsistence activities in Barrow because of their skins. Six to nine
bearded seal hides are used by whalers to cover each of the skin-
covered boats traditionally used for spring whaling. Because of their
valuable hides and large size, bearded seals are specifically sought.
Bearded seals are harvested during the summer months in the Beaufort
Sea (USDI/BLM, 2005). The summer hunt typically occurs near Thetis
Island in July through August (prior to initiation of UAGI's proposed
survey). The animals inhabit the environment around the ice floes in
the drifting ice pack, so hunting usually occurs from boats in the
drift ice. Braund et al. (1993) estimated that 174 bearded seals were
harvested annually at Barrow from 1987 to 1990. The majority of bearded
seal harvest sites from 1987 to 1990 was within approximately 24 km (15
mi) of Point Barrow (Braund et al., 1993), well inshore of the proposed
survey. Along the Chukchi Sea coast, bearded seals are mainly taken
between May and September near Wainwright, during the spring and summer
by Point Hope hunters, and throughout the year by Point Lay hunters.
These hunts occur closer into shore than the proposed survey area or
the proposed transit route.
Potential Impacts to Subsistence Uses
NMFS has defined ``unmitigable adverse impact'' in 50 CFR 216.103
as:
* * * an impact resulting from the specified activity: (1) That is
likely to reduce the availability of the species to a level
insufficient for a harvest to meet subsistence needs by: (i) Causing
the marine mammals to abandon or avoid hunting areas; (ii) Directly
displacing subsistence users; or (iii) Placing physical barriers
between the marine mammals and the subsistence hunters; and (2) That
cannot be sufficiently mitigated by other measures to increase the
availability of marine mammals to allow subsistence needs to be met.
Noise emitted during the proposed seismic survey from the acoustic
sources has the potential to impact marine mammals hunted by Native
Alaskans. In the case of cetaceans, the most common reaction to
anthropogenic sounds (as noted previously in this document) is
avoidance of the ensonified area. In the case of bowhead whales, this
often means that the animals divert from their normal migratory path by
several kilometers. However, because the proposed survey occurs so far
from any of the traditional hunting grounds and to the west of the fall
bowhead hunting areas (meaning the whales would reach the hunting
grounds before entering the survey area), it is not anticipated that
there will be impacts to subsistence uses.
Plan of Cooperation (POC)
Regulations at 50 CFR 216.104(a)(12) require MMPA authorization
applicants for activities that take place in Arctic waters to provide a
POC or information that identifies what measures have been taken and/or
will be taken to minimize adverse effects on the availability of marine
mammals for subsistence purposes. UAGI has worked with the people of
the North Slope Borough (NSB) to identify and avoid areas of potential
conflict. The project's principal investigator (PI) contacted Dr. Glenn
Sheehan of the Barrow Arctic Science Consortium and NSB biologist, Dr.
Robert Suydam, on January 7, 2010, to inform them of the proposed study
and the elements intended to minimize potential subsistence conflict.
The PI presented the proposed UAGI survey at a meeting of the Alaska
Eskimo Whaling Commission (AEWC) in Barrow on February 11, 2010. He
explained the survey plans to the local residents, including NSB
Department of Wildlife Management biologists, consulted with
stakeholders about their concerns, and discussed the aspects of the
survey designed to mitigate impacts. No major concerns were expressed.
The PI also attended the 2011 AEWC meeting on February 17-18;
representatives from all NSB communities attended. The only concern
expressed was that AEWC would like a good communication link with the
Langseth during the survey. As requested by AEWC, communication lines
between the NSB and the Langseth during the survey will be kept open in
order to minimize potential conflicts. The study was also presented to
government agencies, affected stakeholders, and the general public at
the annual Arctic Open-water Meeting in Anchorage, Alaska, on March 7-
8, 2011.
As part of its MMPA IHA application, UAGI submitted a POC to NMFS.
As noted in the POC, a Barrow resident knowledgeable about the mammals
and fish of the area is expected to be included as a PSO aboard the
Langseth. Although the primary duty of this individual will be as a
member of the PSO team responsible for implementing the monitoring and
mitigation requirements, this person will also be able to act as a
liaison with hunters if they are encountered at sea. However, the
proposed activity has been timed so as to avoid overlap with the main
harvests of marine mammals (especially bowhead whales). Meetings with
whaling captains, other community representatives, the AEWC, NSB, and
any other parties to the POC have been and will continue to be held, as
necessary, to negotiate the terms of the POC and to coordinate the
planned seismic survey operations with subsistence activity.
Unmitigable Adverse Impact Analysis and Preliminary Determination
NMFS has preliminarily determined that UAGI's proposed marine
seismic survey in the Arctic Ocean will not have an unmitigable adverse
impact on the availability of marine mammal species or stocks for
taking for subsistence uses.
[[Page 41486]]
This preliminary determination is supported by the fact that UAGI and
NSF have worked closely with the AEWC and NSB to ensure that the
proposed activities are not co-located with annual subsistence
activities. Additionally, the proposed seismic survey will occur more
than 200 km (124 mi) offshore of the North Slope and to the west of the
communities that conduct fall bowhead whale subsistence hunts. This
means that the whales will reach the communities prior to entering into
the proposed survey area. The Chukchi Sea beluga hunts are typically
completed prior to the time the Langseth would be transiting through
the Chukchi Sea to the survey site. Should late summer or early fall
hunts of certain species be occurring at the time of transit of the
vessel, the hunts occur closer into shore than the proposed transit
route of the Langseth.
Based on the measures described in UAGI's POC, the proposed
mitigation and monitoring measures (described earlier in this
document), and the project design itself, NMFS has determined
preliminarily that there will not be an unmitigable adverse impact on
subsistence uses from UAGI's marine seismic survey.
Endangered Species Act (ESA)
Three of the marine mammal species that could occur in the proposed
seismic survey area are listed under the ESA: Bowhead whale; humpback
whale; and fin whale. Under Section 7 of the ESA, NSF has initiated
formal consultation with the NMFS, Office of Protected Resources,
Endangered Species Division, on this proposed seismic survey. NMFS's
Office of Protected Resources, Permits, Conservation and Education
Division, has also initiated formal consultation under section 7 of the
ESA with NMFS' Office of Protected Resources, Endangered Species
Division, to obtain a Biological Opinion evaluating the effects of
issuing the IHA on ESA-listed 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, UAGI, 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 NSF and
NMFS's Office of Protected Resources. Although the ringed seal and
bearded seal have been proposed for listing under the ESA, neither of
the listings will be finalized prior to conclusion of the proposed
seismic survey. Therefore, consultation pursuant to section 7 of the
ESA is not needed for these species.
National Environmental Policy Act (NEPA)
With its complete application, UAGI and NSF provided NMFS an EA
analyzing 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. The EA, prepared by
LGL on behalf of NSF is entitled ``Environmental Assessment of a Marine
Geophysical Survey by the R/V Marcus G. Langseth in the Arctic Ocean,
September-October 2011.'' Prior to making a final decision on the IHA
application, NMFS will either prepare an independent EA, or, after
review and evaluation of the NSF EA for consistency with the
regulations published by the Council on Environmental Quality and NOAA
Administrative Order 216-6, Environmental Review Procedures for
Implementing the National Environmental Policy Act, adopt the NSF EA
and make a decision of whether or not to issue a Finding of No
Significant Impact.
Proposed Authorization
As a result of these preliminary determinations, NMFS proposes to
authorize the take of marine mammals incidental to UAGI's proposed
marine seismic survey in the Arctic Ocean, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated.
Dated: July 11, 2011.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2011-17765 Filed 7-13-11; 8:45 am]
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