[Federal Register Volume 76, Number 88 (Friday, May 6, 2011)]
[Notices]
[Pages 26255-26279]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-11152]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA343


Takes of Marine Mammals Incidental to Specified Activities; 
Marine Geophysical Survey in the Western Gulf of Alaska, June to 
August, 2011

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Notice; proposed Incidental Harassment Authorization; request 
for comments.

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SUMMARY: NMFS has received an application from the Lamont-Doherty Earth 
Observatory of Columbia University (L-DEO) for an Incidental Harassment 
Authorization (IHA) to take marine mammals, by harassment, incidental 
to conducting a marine geophysical survey in the western Gulf of Alaska 
(GOA), June to August, 2011. Pursuant to the Marine Mammal Protection 
Act (MMPA), NMFS is requesting comments on its proposal to issue an IHA 
to L-DEO to incidentally harass, by Level B harassment only, 16 species 
of marine mammals during the specified activity.

DATES: Comments and information must be received no later than June 6, 
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.
    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#applications without change. All Personal Identifying 
Information (for example, name, address, etc.) voluntarily submitted by 
the commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.
    A copy of the application containing a list of the references used 
in this document may be obtained by writing to the above address, 
telephoning the contact listed here (see FOR FURTHER INFORMATION 
CONTACT) or visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
    The L-DEO, with support from the National Science Foundation (NSF), 
has prepared a draft ``Environmental Assessment (EA) of a Marine 
Geophysical Survey by the R/V Marcus G. Langseth in the western Gulf of 
Alaska, July-August 2011,'' prepared by LGL Ltd., Environmental 
Research Associates (LGL), on behalf of L-DEO, which is also available 
at the same internet address. Documents cited in this notice may be 
viewed, by appointment, during regular business hours, at the 
aforementioned address.

FOR FURTHER INFORMATION CONTACT: Howard Goldstein or Jolie Harrison, 
Office of Protected Resources, NMFS, (301) 713-2289, ext. 172.

SUPPLEMENTARY INFORMATION:

Background

    Section 101(a)(5)(D) of the MMPA (16 U.S.C. 1371 (a)(5)(D)) directs 
the Secretary of Commerce (Secretary) to authorize, upon request, the 
incidental, but not intentional, taking of small numbers of marine 
mammals of a species or population stock, by United States citizens who 
engage in a specified activity (other than commercial fishing) within a 
specified geographical region if certain findings are made and, if the 
taking is limited to harassment, a notice of a proposed authorization 
is provided to the public for review.
    Authorization for the incidental taking of small numbers of marine 
mammals shall be granted if NMFS finds that the taking will have a 
negligible impact on the species or stock(s), and will not have an 
unmitigable adverse impact on the availability of the species or 
stock(s) for subsistence uses (where relevant). The authorization must 
set forth the permissible methods of taking, other means of effecting 
the least practicable adverse impact on the species or stock and its 
habitat, and requirements pertaining to the mitigation, monitoring and 
reporting of such takings. NMFS has defined ``negligible impact'' in 50 
CFR 216.103 as ``* * * an impact resulting from the specified activity 
that cannot be reasonably expected to, and is not reasonably likely to, 
adversely affect the species or stock through effects on annual rates 
of recruitment or survival.''
    Section 101(a)(5)(D) of the MMPA established an expedited process 
by which citizens of the United States can apply for an authorization 
to incidentally take small numbers of marine mammals by harassment. 
Section 101(a)(5)(D) of the MMPA

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establishes a 45-day time limit for NMFS' review of an application 
followed by a 30-day public notice and comment period on any proposed 
authorizations for the incidental harassment of small numbers of marine 
mammals. Within 45 days of the close of the public comment period, NMFS 
must either issue or deny the authorization.
    Except with respect to certain activities not pertinent here, the 
MMPA defines ``harassment'' as ``any act of pursuit, torment, or 
annoyance which (i) has the potential to injure a marine mammal or 
marine mammal stock in the wild [Level A harassment]; or (ii) has the 
potential to disturb a marine mammal or marine mammal stock in the wild 
by causing disruption of behavioral patterns, including, but not 
limited to, migration, breathing, nursing, breeding, feeding, or 
sheltering [Level B harassment].''

Summary of Request

    NMFS received an application on April 1, 2010, from L-DEO for the 
taking by harassment, of marine mammals, incidental to conducting a 
marine geophysical survey in the western GOA within the U.S. Exclusive 
Economic Zone (EEZ) in depths from approximately 25 meters (m) (82 feet 
[ft]) to greater than 6,000 m (19,685 ft). The cruise was postponed in 
2010 and rescheduled for 2011. NMFS received a revised application on 
March 4, 2011 from L-DEO. L-DEO plans to conduct the proposed survey 
from approximately June 28 to August 4, 2011.
    L-DEO plans to use one source vessel, the R/V Marcus G. Langseth 
(Langseth) and a seismic airgun array to collect seismic reflection and 
refraction profiles from the Shumagin Islands to east of Kodiak Island 
in the GOA. In addition to the proposed operations of the seismic 
airgun array, L-DEO intends to operate a multibeam echosounder (MBES) 
and a sub-bottom profiler (SBP) continuously throughout the survey.
    Acoustic stimuli (i.e., increased underwater sound) generated 
during the operation of the seismic airgun array may have the potential 
to cause a short-term behavioral disturbance for marine mammals in the 
survey area. This is the principal means of marine mammal taking 
associated with these activities and L-DEO has requested an 
authorization to take 16 species of marine mammals by Level B 
harassment. Take is not expected to result from the use of the MBES or 
SBP, for reasons discussed 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 38 days). 
It is likely that any marine mammal would be able to avoid the vessel.

Description of the Specified Activity

    L-DEO's proposed seismic survey in the western GOA, from the 
Shumagin Islands to east of Kodiak Island, will take place during June 
to August, 2011, in the area 52.5[deg] to 59[deg] North, 147.5[deg] to 
161[deg] West (see Figure 1 of the IHA application). The proposed 
seismic survey will take place in water depths ranging from 25 m (82 
ft) to greater than 6,000 m (82 to 19,685 ft) and consists of 
approximately 2,553 kilometers (km) (1,378.5 nautical miles [nmi]) of 
transect lines in the study area. The project is scheduled to occur 
from approximately June 28 to August 4, 2011. Some minor deviation from 
these dates is possible, depending on logistics and weather.
    The proposed seismic survey will collect seismic reflection and 
refraction data to characterize the subduction zone off southern 
Alaska, which produces large and destructive earthquakes. The data from 
this study will be used to: (1) Estimate the size of the seismogenic 
zone, the portion of the fault that controls the magnitude of 
earthquakes, and (2) provide critical information on how the properties 
of the seismogenic zone change along the subduction zone such that some 
areas produce large earthquakes and others do not. The proposed study 
focuses on the Semidi segment, whose earthquake recurrence interval is 
50 to 75 years and which last ruptured in 1938.
    The survey will involve one source vessel, the Langseth. The 
Langseth will deploy an array of 36 airguns as an energy source at a 
tow depth of 12 m (39.4 ft). The receiving system will consist of two 8 
km (4.3 nmi) long hydrophone streamers and/or 21 ocean bottom 
seismometers (OBSs). As the airgun is towed along the survey lines, the 
hydrophone streamers will receive the returning acoustic signals and 
transfer the data to the on-board processing system. The OBSs record 
the returning acoustic signals internally for later analysis.
    The planned seismic survey (e.g., equipment testing, startup, line 
changes, repeat coverage of any areas, and equipment recovery) will 
consist of approximately 2,553 km of transect lines in the western GOA 
survey area (see Figure 1 of the IHA application). Just over half of 
the survey (1,363 km [736 nmi]) will take place in water deeper than 
1,000 m; 30% or 754 km (407.1 nmi) will be surveyed in intermediate 
depth (100 to 1,000 m) water; and 17% (463 km [250 nmi]) will take 
place in water less than 100 m deep. Approximately 30 km (16.2 nmi) of 
seismic surveying will occur in water less than 40 m deep. A refraction 
survey using OBSs will take place along two lines (lines 3 and 5). 
Following the refraction survey, a multichannel (MCS) survey using two 
hydrophone streamers will take place along all of the transect lines. 
Thus, lines 3 and 5 will be surveyed twice. In addition to the 
operations of the airgun array, a Kongsberg EM 122 MBES and Knudsen 
320B SBP will also be operated from the Langseth continuously 
throughout the cruise. There will be additional seismic operations 
associated with equipment testing, start-up, and possible line changes 
or repeat coverage of any areas where initial data quality is sub-
standard. In L-DEO's calculations, 25% has been added for those 
additional operations.
    All planned geophysical data acquisition activities will be 
conducted by L-DEO, the Langseth's operator, with on-board assistance 
by the scientists who have proposed the study. The Principal 
Investigators are Drs. Donna Shillington, Spahr Webb, and Mladen 
Nedimovic, all of L-DEO. The vessel will be self-contained, and the 
crew will live aboard the vessel for the entire cruise.

Vessel Specifications

    The Langseth, owned by the National Science Foundation, will tow 
the 36 airgun array, as well as the hydrophone streamer, along 
predetermined lines. The Langseth will also deploy and retrieve the 
OBSs. When the Langseth is towing the airgun array and the hydrophone 
streamer, the turning rate of the vessel is limited to five degrees per 
minute. Thus, the maneuverability of the vessel is limited during 
operations with the streamer.
    The vessel has a length of 71.5 m (235 ft); a beam of 17.0 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

[[Page 26257]]

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 (13,499 nmi) (the distance the vessel 
can travel without refueling).
    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

Seismic Airguns

    The Langseth will deploy a 36 airgun array, with a total volume of 
approximately 6,600 cubic inches (in\3\). The airgun array will consist 
of a mixture of Bolt 1500LL and Bolt 1900LLX airguns ranging in size 
from 40 to 360 in\3\, with a firing pressure of 1,900 pounds per square 
inch. The airguns will be configured as four identical linear arrays or 
``strings'' (see Figure 2 of the application). Each string will have 10 
airguns, the first and last airguns in the strings are spaced 16 m (52 
ft) apart. Of the 10 airguns, nine airguns in each string will be fired 
simultaneously, whereas the tenth is kept in reserve as a spare, to be 
turned on in case of failure of another airgun. The four airgun strings 
will be distributed across an area of approximately 24x16 m (78.7 x 
52.5 ft) behind the Langseth and will be towed approximately 100 m (328 
ft) behind the vessel. The shot interval will be relatively short, 50 m 
(164 ft) or approximately 22 seconds (s), for the MCS survey or 
reflection surveying and relatively longer, 280 m (918.6 ft) or 
approximately 120 s, when recording data on the OBSs during the 
refraction survey. The firing pressure of the array is 1,900 pounds per 
square inch (psi). During firing, a brief (approximately 0.1 s) pulse 
sound is emitted; the airguns will be silent during the intervening 
periods. The dominant frequency components range from two to 188 Hertz 
(Hz).
    The tow depth of the array will be 12 m (39.4 ft) during OBS 
refraction and MCS surveys. Because the actual source is a distributed 
sound source (36 airguns) rather than a single point source, the 
highest sound 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.

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 the root mean square unless otherwise noted. SPL 
does not take the duration of a sound into account.

Characteristics of the Airgun Pulses

    Airguns function by venting high-pressure air into the water which 
creates an air bubble. The pressure signature of an individual airgun 
consists of a sharp rise and then fall in pressure, followed by several 
positive and negative pressure excursions caused by the oscillation of 
the resulting air bubble. The oscillation of the air bubble transmits 
sounds downward through the seafloor and the amount of sound 
transmitted in the near horizontal directions is reduced. However, the 
airgun array also emits sounds that travel horizontally toward non-
target areas.
    The nominal source levels of the airgun arrays used by L-DEO on the 
Langseth are 236 to 265 dB re 1 [mu]Pa (p-p) and the rms value for a 
given airgun pulse is typically 16 dB re 1 [mu]Pa lower than the peak-
to-peak value. However, the difference between rms and peak or peak-to-
peak values for a given pulse depends on the frequency content and 
duration of the pulse, among other factors.
    Accordingly, L-DEO has predicted the received sound levels in 
relation to distance and direction from the 36 airgun array and the 
single Bolt 1900LL 40 in\3\ airgun, which will be used during power-
downs. A detailed description of L-DEO's modeling for marine seismic 
source arrays for species mitigation is provided in Appendix A of L-
DEO's EA. These are the nominal source levels applicable to downward 
propagation. The effective source levels for horizontal propagation are 
lower than those for downward propagation when the source consists of 
numerous airguns spaced apart from one another.
    Appendix B of L-DEO's EA discusses the characteristics of the 
airgun pulses. NMFS refers the reviewers to the application and EA 
documents for additional information.

Predicted Sound Levels for the Airguns

    Tolstoy et al., (2009) reported results for propagation 
measurements of pulses from the Langseth's 36 airgun, 6,600 in\3\ array 
in shallow-water (approximately 50 m [164 ft]) and deep-water depths 
(approximately 1,600 m [5,249 ft]) in the Gulf of Mexico in 2007 and 
2008. L-DEO has used these reported and corrected empirical values to 
determine exclusion zones (EZs) for the 36 airgun array and modeled 
measurements for the single airgun; to designate EZs for purposes of 
mitigation, and to estimate take for marine mammals in the GOA.
    Results of the Gulf of Mexico calibration study (Tolstoy et al., 
2009) showed that radii around the airguns for various received levels 
varied with water depth. Empirical measurements from the Gulf of Mexico 
were used for GOA and those measurements were used to determine the 
algorithm for the model. The empirical data for deep water (greater 
than 1,000 m; 3,280 ft) indicated that the L-DEO model (as applied to 
the Langseth's 36 airgun array) overestimated the received sound levels 
at a given distance. For intermediate depths, a correction of the 
empirical measurements for shallow and deep depths were made.
    Using the corrected measurements (airgun array) or model (single 
airgun), Table 1 (below) shows the distances at which three rms sound 
levels are expected to be received from the 36 airgun array and a 
single airgun. The 180 and 190 dB re 1 [mu]Pa (rms) distances are the 
safety criteria for potential Level A harassment as specified by NMFS 
(2000) and are applicable to cetaceans and pinnipeds, respectively. If 
marine mammals are detected within or about to enter the appropriate 
EZ, the airguns will be powered-down (or shut-down, if necessary) 
immediately.
    Table 1 summarizes the predicted distances at which sound levels 
(160,

[[Page 26258]]

180, and 190 dB [rms]) are expected to be received from the 36 airgun 
array and a single airgun operating in deep, intermediate, and shallow 
water depths.

 Table 1--Measured (array) or predicted (single airgun) 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 western
                                           GOA, June to August, 2011.
----------------------------------------------------------------------------------------------------------------
                                                                             Predicted RMS radii distances  (m)
       Source and volume          Tow depth  (m)      Water depth  (m)    --------------------------------------
                                                                              190 dB       180 dB       160 dB
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun (40 in\3\)..  6 to 12.........  Deep (> 1,000 ).......           12           40          385
                                                   Intermediate (100 to             18           60          578
                                                    1,000).                        150          296        1,050
                                                   Shallow (< 100).......
4 Strings, 36 airguns (6,600     12..............  Deep (> 1,000)........          460        1,100        4,400
 in\3\).                                           Intermediate (100 to            615        1,810       13,935
                                                    1,000).                        770        2,520       23,470
                                                   Shallow (<100)........
----------------------------------------------------------------------------------------------------------------

OBS Description and Deployment

    The study will commence with a refraction survey using OBSs. 
Approximately 21 OBSs will be deployed by the Langseth at the beginning 
of the survey along one transect. After data are collected along this 
transect line, the OBSs will be picked up, and they will be re-deployed 
along the next refraction line. At the end of the refraction survey 
(approximately 3 days of seismic operations), all OBSs will be 
retrieved. OBS deployment is expected to take approximately 3 days, and 
OBS retrieval will take approximately 5 days.
    Scripps Institution of Oceanography LC4x4 OBSs will be used during 
the cruise. This OBS has a volume of approximately 1 m\3\, with an 
anchor that consists of a large piece of steel grating (approximately 1 
m\2\). Once an OBS is ready to be retrieved, an acoustic release 
transponder interrogates the OBS at a frequency of 9 to 11 kHz, and a 
response is received at a frequency of 9 to 13 kHz. The burn-wire 
release assembly is then activated, and the instrument is released from 
the anchor to float to the surface.
    Along with the airgun operations, two additional acoustical data 
acquisition systems will be operated from the Langseth continuously 
during the survey. The ocean floor will be mapped with the Kongsberg EM 
122 MBES and a Knudsen 320B SBP. These sound sources will be operated 
continuously from the Langseth throughout the cruise.

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, usually 12 kHz) in a fan-shaped beam that extends downward 
and to the sides of the ship. The transmitting beamwidth is 1[deg] or 
2[deg] fore-aft and 150[deg] athwartship and the maximum source level 
is 242 dB re: 1 [mu]Pa.
    Each ping consists of eight (in water greater than 1,000 m) or four 
(less than 1,000 m) 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 FM chirp pulses up to 100 ms long are used 
in water greater than 2,600 m. The successive transmissions span an 
overall cross-track angular extent of about 150[deg], with 2 ms gaps 
between the pulses for successive sectors.

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 one second, but a common mode 
of operation is to broadcast five pulses at one second intervals 
followed by a five second pause.
    NMFS expects that acoustic stimuli resulting from the proposed 
operation of the single airgun or the 36 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 (4.6 knots [kts]; 8.5 km/hr; 5.3 mph) 
during seismic acquisition.

Description of the Proposed Dates, Duration, and Specified Geographic 
Region

    The survey will occur in the western GOA in the area 52.5[deg] to 
59[deg] North, 147.5 to 161[deg] West. The seismic survey will take 
place in water depths of 25 m to greater than 6,000 m. The Langseth 
will depart from Kodiak, Alaska on approximately June 28, 2011. The 
program will start with a refraction survey using OBSs. Approximately 
21 OBSs will be deployed along one line; the OBSs will then be 
retrieved and re-deployed along the next refraction line. OBS 
deployment will take approximately three days and recovery will take 
approximately five days; there will be a total of approximately three 
days of refraction shooting. Following the refraction survey, the MCS 
survey will take place using the two streamers. MCS and airgun 
deployment will take approximately three days, and there will be 
approximately 13 days of MCS operations. Upon completion of seismic 
operations, all gear will be picked up and the vessel will travel to 
Dutch Harbor, for arrival on approximately August 4, 2011. Seismic 
operations in the study area will be carried out for approximately 16 
days. Some minor deviation from this schedule is possible, depending on 
logistics and weather (i.e., the cruise may depart earlier or be 
extended due to poor weather; there could be an additional three days 
of seismic operations if collected data are deemed to be of substandard 
quality).

[[Page 26259]]

Description of the Marine Mammals in the Area of the Proposed Specified 
Activity

    Twenty-five marine mammal species (18 cetacean, 6 pinniped, and the 
sea otter) are known to or could occur in the GOA study area. Several 
of these species are listed as endangered under the U.S. Endangered 
Species Act of 1973 (ESA; 16 U.S.C. 1531 et seq.), including the North 
Pacific right (Eubalaena japonica), humpback (Megaptera novaeangliae), 
sei (Balaenoptera borealis), fin (Balaenoptera physalus), blue 
(Balaenoptera musculus), and sperm (Physeter macrocephalus) whales, as 
well as the Cook Inlet distinct population segment (DPS) of beluga 
whales (Dephinapterus leucas) and the western stock of Steller sea 
lions (Eumetopias jubatus). The eastern stock of Steller sea lions is 
listed as threatened, as is the southwest Alaska DPS of the sea otter 
(Enhydra lutris).
    The marine mammals that occur in the proposed survey area belong to 
four taxonomic groups: odontocetes (toothed cetaceans, such as 
dolphins), mysticetes (baleen whales), pinnipeds (seals, sea lions, and 
walrus), and fissipeds (sea otter). Cetaceans and pinnipeds are the 
subject of the IHA application to NMFS. Walrus sightings are rare in 
the GOA. Sea otters generally inhabit nearshore areas inside the 40 m 
(131.2 ft) depth contour (Riedman and Estes, 1990) and could be 
encountered in coastal waters, but likely would not be encountered in 
the deep, offshore waters of the study area. The sea otter and Pacific 
walrus are two marine mammal species mentioned in this document that 
are managed by the U.S. Fish and Wildlife Service (USFWS) and are not 
considered further in this analysis; all others are managed by NMFS. 
The Cook Inlet DPS of beluga whales, California sea lions (Zalophus c. 
californianus), northern fur seals (Callorhinus ursinus), and northern 
elephant seals (Mirounga angustirostris) are not likely to be found in 
the waters of the survey area.
    Table 2 (below) presents information on the abundance, 
distribution, population status, conservation status, and density of 
the marine mammals that may occur in the proposed survey area during 
June to August, 2011.
BILLING CODE 3510-22-P

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[GRAPHIC] [TIFF OMITTED] TN06MY11.057


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[GRAPHIC] [TIFF OMITTED] TN06MY11.058


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[GRAPHIC] [TIFF OMITTED] TN06MY11.059

BILLING CODE 3510-22-C
    Refer to Section III and IV of L-DEO's application for detailed 
information regarding the abundance and distribution, population 
status, and life history and behavior of these species and their 
occurrence in the proposed project area. The application also presents 
how L-DEO calculated the estimated densities for the marine mammals in 
the proposed survey area. NMFS has reviewed these data and determined 
them to be the best available scientific information for the purposes 
of the proposed IHA.

Potential Effects on Marine Mammals

    Acoustic stimuli generated by the operation of the airguns, which 
introduce sound into the marine environment, may have the potential to 
cause Level B harassment of marine mammals in the proposed survey area. 
The effects of sounds from airgun operations might include one or more 
of the following: Tolerance, masking of natural sounds, behavioral 
disturbance, temporary or permanent hearing impairment, or non-auditory 
physical or physiological effects (Richardson et al., 1995; Gordon et 
al., 2004; Nowacek et al., 2007; Southall et al., 2007).
    Permanent hearing impairment, in the unlikely event that it 
occurred, would constitute injury, but temporary threshold shift (TTS) 
is not an injury (Southall et al., 2007). Although the possibility 
cannot be entirely excluded, it is unlikely that the proposed project 
would result in any cases of temporary or permanent hearing impairment, 
or any significant non-auditory physical or physiological effects. 
Based on the available data and studies described here, some behavioral 
disturbance is expected, but NMFS expects the disturbance to be 
localized and short-term.

Tolerance to Sound

    Studies on marine mammals' tolerance to sound in the natural

[[Page 26263]]

environment are relatively rare. Richardson et al. (1995) defines 
tolerance as the occurrence of marine mammals in areas where they are 
exposed to human activities or man-made noise. In many cases, tolerance 
develops by the animal habituating to the stimulus (i.e., the gradual 
waning of responses to a repeated or ongoing stimulus) (Richardson et 
al., 1995; Thorpe, 1963), but because of ecological or physiological 
requirements, many marine animals may need to remain in 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. She 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 of Natural Sounds

    The term masking refers to the inability of a subject to recognize 
the occurrence of an acoustic stimulus as a result of the interference 
of another acoustic stimulus (Clark et al., 2009). Introduced 
underwater sound may, through masking, reduce the effective 
communication distance of a marine mammal species if the frequency of 
the source is close to that used as a signal by the marine mammal, and 
if the anthropogenic sound is present for a significant fraction of the 
time (Richardson et al., 1995).
    Masking effects of pulsed sounds (even from large arrays of 
airguns) on marine mammal calls and other natural sounds are expected 
to be limited. Because of the intermittent nature and low duty cycle of 
seismic airgun pulses, animals can emit and receive sounds in the 
relatively quiet intervals between pulses. However, in some situations, 
reverberation occurs for much or the entire interval between pulses 
(e.g., Simard et al., 2005; Clark and Gagnon, 2006) which could mask 
calls. Some baleen and toothed whales are known to continue calling in 
the presence of seismic pulses, and their calls can usually be heard 
between the seismic pulses (e.g., Richardson et al., 1986; McDonald et 
al., 1995; Greene et al., 1999; Nieukirk et al., 2004; Smultea et al., 
2004; Holst et al., 2005a,b, 2006; and Dunn and Hernandez, 2009). 
However, Clark and Gagnon (2006) reported that fin whales in the 
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 dominant 
components of airgun sounds, thus limiting the potential for masking.
    In general, NMFS expects the masking effects of seismic pulses to 
be minor, given the normally intermittent nature of seismic pulses. 
Refer to Appendix B(4) of L-DEO's 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-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 
(Balaena mysticetus), 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 kms, even 
though the airgun pulses remain well above ambient noise levels out to 
much longer distances. However, as reviewed in Appendix B (5) of L-
DEO'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 four to 15 km 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 L-

[[Page 26264]]

DEO'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 
source level of 227 dB re 1 [micro]Pa (p-p). In the 1998 study, they 
documented that avoidance reactions began at five to eight km from the 
array, and that those reactions kept most pods approximately three to 
four km from the operating seismic boat. In the 2000 study, they noted 
localized displacement during migration of four to five km by traveling 
pods and seven to 12 km by more sensitive resting pods of cow-calf 
pairs. Avoidance distances with respect to the single airgun were 
smaller but consistent with the results from the full array in terms of 
the received sound levels. The mean received level for initial 
avoidance of an approaching airgun was 140 dB re 1 [mu]Pa (rms) for 
humpback pods containing females, and at the mean closest point of 
approach distance the received level was 143 dB re 1 [mu]Pa (rms). The 
initial avoidance response generally occurred at distances of five to 
eight km from the airgun array and two km from the single airgun. 
However, some individual humpback whales, especially males, approached 
within distances of 100 to 400 m (328 to 1,312 ft), where the maximum 
received level was 179 dB re 1 [mu]Pa (rms).
    Data collected by observers during several seismic surveys in the 
Northwest Atlantic showed that sighting rates of humpback whales were 
significantly greater during non-seismic periods compared with periods 
when a full array was operating (Moulton and Holst, 2010). In addition, 
humpback whales were more likely to swim away and less likely to swim 
towards a vessel during seismic vs. non-seismic periods (Moulton and 
Holst, 2010).
    Humpback whales on their summer feeding grounds in southeast Alaska 
did not exhibit persistent avoidance when exposed to seismic pulses 
from a 1.64-L (100 in\3\) airgun (Malme et al., 1985). Some humpbacks 
seemed ``startled'' at received levels of 150 to 169 dB re 1 [mu]Pa. 
Malme et al. (1985) concluded that there was no clear evidence of 
avoidance, despite the possibility of subtle effects, at received 
levels up to 172 dB re 1 [mu]Pa (rms). However, Moulton and Holst 
(2010) reported that humpback whales monitored during seismic surveys 
in the Northwest Atlantic had lower sighting rates and were most often 
seen swimming away from the vessel during seismic periods compared with 
periods when airguns were silent.
    Studies have suggested that south Atlantic humpback whales 
wintering off Brazil may be displaced or even strand upon exposure to 
seismic surveys (Engel et al., 2004). The evidence for this was 
circumstantial and subject to alternative explanations (IAGC, 2004). 
Also, the evidence was not consistent with subsequent results from the 
same area of Brazil (Parente et al., 2006), or with direct studies of 
humpbacks exposed to seismic surveys in other areas and seasons. After 
allowance for data from subsequent years, there was no observable 
direct correlation between strandings and seismic surveys (IWC, 
2007:236).
    There are no data on reactions of right whales to seismic surveys, 
but results from the closely-related bowhead whale show that their 
responsiveness can be quite variable depending on their activity 
(migrating versus 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 
to 30 km 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 L-DEO'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 percent of 
feeding gray whales stopped feeding at an average received pressure 
level of 173 dB re 1 [mu]Pa on an (approximate) rms basis, and that 10 
percent of feeding whales interrupted feeding at received levels of 163 
dB re 1 [micro]Pa (rms). Those findings were generally consistent with 
the results of experiments conducted on larger numbers of gray whales 
that were migrating along the California coast (Malme et al., 1984; 
Malme and Miles, 1985), and western Pacific gray whales feeding off 
Sakhalin Island, Russia (Wursig et al., 1999; Gailey et al., 2007; 
Johnson et al., 2007; Yazvenko et al., 2007a, b), along with data on 
gray whales off British Columbia (Bain and Williams, 2006).
    Various species of Balaenoptera (blue, sei, fin, and minke whales) 
have occasionally been seen in areas ensonified by airgun pulses 
(Stone, 2003; MacLean and Haley, 2004; Stone and Tasker, 2006), and 
calls from blue and fin whales have been localized in areas with airgun 
operations (e.g., McDonald et al., 1995; Dunn and Hernandez, 2009; 
Castellote et al., 2010). Sightings by observers on seismic vessels off 
the United Kingdom from 1997 to 2000 suggest that, during times of good 
sightability, sighting rates for mysticetes (mainly fin and sei whales) 
were similar when large arrays of airguns were shooting vs. silent 
(Stone, 2003; Stone and Tasker, 2006). However, these whales tended to 
exhibit localized avoidance, remaining significantly further (on 
average) from the airgun array during seismic operations compared with 
non-seismic periods (Stone and Tasker, 2006). Castellote et al. (2010) 
reported that singing fin whales in the Mediterranean moved away from 
an operating airgun array.
    Ship-based monitoring studies of baleen whales (including blue, 
fin, sei, minke, and humpback whales) in the Northwest Atlantic found 
that overall, this group had lower sighting rates during seismic vs. 
non-seismic periods (Moulton and Holst, 2010). Baleen whales as a group 
were also seen significantly farther from the vessel during seismic 
compared with non-seismic periods, and they were more often seen to be 
swimming away from the operating seismic vessel (Moulton and Holst, 
2010). Blue and minke whales were initially sighted significantly 
farther from the vessel during seismic operations compared to non-
seismic periods; the same trend was observed for fin whales (Moulton 
and Holst, 2010). Minke whales were most often observed to be swimming 
away from the vessel when seismic operations were underway (Moulton and 
Holst, 2010).
    Data on short-term reactions by cetaceans to impulsive noises are 
not necessarily indicative of long-term or biologically significant 
effects. It is not known whether impulsive sounds affect reproductive 
rate or distribution and

[[Page 26265]]

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 L-DEO'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 one km or less, and some individuals show no apparent 
avoidance. The beluga whale (Delphinapterus leucas) 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 to 20 km compared with 20 to 30 km from an operating 
airgun array, and observers on seismic boats in that area rarely see 
belugas (Miller et al., 2005; Harris et al., 2007).
    Captive bottlenose dolphins (Tursiops truncatus) 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 L-DEO's EA for 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 (Hyperoodon ampullatus) remained in the general area and 
continued to produce high-frequency clicks when exposed to sound pulses 
from distant seismic surveys (Gosselin and Lawson, 2004; Laurinolli and 
Cochrane, 2005; Simard et al., 2005). Most beaked whales tend to avoid 
approaching vessels of other types (e.g., Wursig et al., 1998). They 
may also dive for an extended period when approached by a vessel (e.g., 
Kasuya, 1986), although it is uncertain how much longer such dives may 
be as compared to dives by undisturbed beaked whales, which also are 
often quite long (Baird et al., 2006; Tyack et al., 2006). Based on a 
single observation, Aguilar-Soto et al. (2006) suggested that foraging 
efficiency of Cuvier's beaked whales may be reduced by close approach 
of vessels. In any event, it is likely that most beaked whales would 
also show strong avoidance of an approaching seismic vessel, although 
this has not been documented explicitly. In fact, Moulton and Holst 
(2010) reported 15 sightings of beaked whales during seismic studies in 
the Northwest Atlantic; seven of those sightings were made at times 
when at least one airgun was operating. There was little evidence to 
indicate that beaked whale behavior was affected by airgun operations; 
sighting rates and distances were similar during seismic and non-
seismic periods (Moulton and Holst, 2010).
    There are increasing indications that some beaked whales tend to 
strand when naval exercises involving mid-frequency sonar operation are 
ongoing nearby (e.g., Simmonds and Lopez-Jurado, 1991; Frantzis, 1998; 
NOAA and USN, 2001; Jepson et al., 2003; Hildebrand, 2005; Barlow and 
Gisiner, 2006; see also the Stranding and Mortality section in this 
notice). These strandings are apparently a disturbance response, 
although auditory or other injuries or other physiological effects may 
also be involved. Whether beaked whales would ever react similarly to 
seismic surveys is unknown. Seismic survey sounds are quite different 
from those of the sonar in operation during the above-cited incidents.
    Odontocete reactions to large arrays of airguns are variable and, 
at least for delphinids and Dall's porpoises, seem to be confined to a 
smaller radius than has been observed for the more responsive of the 
mysticetes, belugas, and harbor porpoises (Appendix B of L-DEO's EA).
    Pinnipeds--Pinnipeds are not likely to show a strong avoidance 
reaction to the airgun array. 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 L-DEO's 
EA. In the Beaufort Sea, some ringed

[[Page 26266]]

seals avoided an area of 100 m to (at most) a few hundred meters around 
seismic vessels, but many seals remained within 100 to 200 m (328 to 
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

    Exposure to high intensity sound for a sufficient duration may 
result in auditory effects such as a noise-induced threshold shift--an 
increase in the auditory threshold after exposure to noise (Finneran, 
Carder, Schlundt, and Ridgway, 2005). Factors that influence the amount 
of threshold shift include the amplitude, duration, frequency content, 
temporal pattern, and energy distribution of noise exposure. The 
magnitude of hearing threshold shift normally decreases over time 
following cessation of the noise exposure. The amount of threshold 
shift just after exposure is called the initial threshold shift. If the 
threshold shift eventually returns to zero (i.e., the threshold returns 
to the pre-exposure value), it is called temporary threshold shift 
(TTS) (Southall et al., 2007).
    Researchers have studied TTS in certain captive odontocetes and 
pinnipeds exposed to strong sounds (reviewed in Southall et al., 2007). 
However, there has been no specific documentation of TTS let alone 
permanent hearing damage, i.e., permanent threshold shift (PTS), in 
free-ranging marine mammals exposed to sequences of airgun pulses 
during realistic field conditions.
    Temporary Threshold Shift--TTS is the mildest form of hearing 
impairment that can occur during exposure to a strong sound (Kryter, 
1985). While experiencing TTS, the hearing threshold rises and a sound 
must be stronger in order to be heard. At least in terrestrial mammals, 
TTS can last from minutes or hours to (in cases of strong TTS) days. 
For sound exposures at or somewhat above the TTS threshold, hearing 
sensitivity in both terrestrial and marine mammals recovers rapidly 
after exposure to the noise ends. Few data on sound levels and 
durations necessary to elicit mild TTS have been obtained for marine 
mammals, and none of the published data concern TTS elicited by 
exposure to multiple pulses of sound. Available data on TTS in marine 
mammals are summarized in Southall et al. (2007). Table 1 (above) 
presents the distances from the Langseth's airguns at which the 
received energy level (per pulse, flat-weighted) would be expected to 
be greater than or equal to 180 dB re 1 [micro]Pa (rms).
    To avoid the potential for injury, NMFS (1995, 2000) concluded that 
cetaceans should not be exposed to pulsed underwater noise at received 
levels exceeding 180 dB re 1 [mu]Pa (rms). NMFS believes that to avoid 
the potential for permanent physiological damage (Level A harassment), 
cetaceans should not be exposed to pulsed underwater noise at received 
levels exceeding 180 dB re 1 [mu]Pa (rms). The 180 dB level is a 
shutdown criterion applicable to cetaceans, as specified by NMFS 
(2000); these levels were used to establish the EZs. NMFS also assumes 
that cetaceans exposed to levels exceeding 160 dB re 1 [mu]Pa (rms) may 
experience Level B harassment.
    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). 
From this, it is suspected that received levels causing TTS onset may 
also be higher in baleen whales (Southall et al., 2007). For this 
proposed study, L-DEO expects no cases of TTS given the strong 
likelihood that baleen whales 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 an 
SEL of approximately 171 dB re 1 [mu]Pa\2\[middot]s (Southall et al., 
2007) which would be equivalent to a single pulse with a received level 
of approximately 181 to 186 dB re 1 [micro]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).
    Permanent Threshold Shift--When PTS occurs, there is physical 
damage to the sound receptors in the ear. In severe cases, there can be 
total or partial deafness, whereas in other cases, the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985). There is no specific evidence that exposure to pulses of airgun 
sound can cause PTS in any marine mammal, even with large arrays of 
airguns. However, given the possibility that mammals close to an airgun 
array might incur at least mild TTS, there has been further speculation 
about the possibility that some individuals occurring very close to 
airguns might incur PTS (e.g., Richardson et al., 1995, p. 372ff; 
Gedamke et al., 2008). Single or occasional occurrences of mild TTS are 
not indicative of permanent auditory damage, but repeated or (in some 
cases) single exposures to a level well above that causing TTS onset 
might elicit PTS.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, but are assumed to be similar to those in humans and 
other terrestrial mammals. PTS might occur at a received sound level at 
least several dBs above that inducing mild TTS if the animal were 
exposed to strong sound pulses with rapid rise time--see Appendix B(6) 
of L-DEO'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,

[[Page 26267]]

and probably greater than six dB (Southall et al., 2007).
    Given the higher level of sound necessary to cause PTS as compared 
with TTS, it is considerably less likely that PTS would occur. Baleen 
whales generally avoid the immediate area around operating seismic 
vessels, as do some other marine mammals.
    Stranding and Mortality--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, an 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 L-DEO'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 exposed to sonar. However, the evidence for this remains 
circumstantial and associated with exposure to naval mid-frequency 
sonar, not seismic surveys (Cox et al., 2006; Southall et al., 2007).
    Seismic pulses and mid-frequency sonar signals are quite different, 
and some mechanisms by which sonar sounds have been hypothesized to 
affect beaked whales are unlikely to apply to airgun pulses. Sounds 
produced by airgun arrays are broadband impulses with most of the 
energy below one kHz. Typical military mid-frequency sonar emits non-
impulse sounds at frequencies of two to 10 kHz, generally with a 
relatively narrow bandwidth at any one time. A further difference 
between seismic surveys and naval exercises is that naval exercises can 
involve sound sources on more than one vessel. Thus, it is not 
appropriate to 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 (Ziphius 
cavirostris) in the Gulf of California, Mexico, when the L-DEO vessel 
R/V Maurice Ewing was operating a 20 airgun (8,490 in \3\) array in the 
general area. The link between the stranding and the seismic surveys 
was inconclusive and not based on any physical evidence (Hogarth, 2002; 
Yoder, 2002). Nonetheless, the Gulf of California incident plus the 
beaked whale strandings near naval exercises involving use of mid-
frequency sonar suggests a need for caution in conducting seismic 
surveys in areas occupied by beaked whales until more is known about 
effects of seismic surveys on those species (Hildebrand, 2005). No 
injuries of beaked whales are anticipated during the proposed study 
because of:
    (1) The high likelihood that any beaked whales nearby would avoid 
the approaching vessel before being exposed to high sound levels, and
    (2) Differences between the sound sources operated by L-DEO and 
those involved in the naval exercises associated with strandings.
    Non-auditory Physiological Effects--Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, resonance, and other types of organ or 
tissue damage (Cox et al., 2006; Southall et al., 2007). Studies 
examining such effects are limited. However, resonance effects (Gentry, 
2002) and direct noise-induced bubble formations (Crum et al., 2005) 
are implausible in the case of exposure to an impulsive broadband 
source like an airgun array. If seismic surveys disrupt diving patterns 
of deep-diving species, this might perhaps result in bubble formation 
and a form of the bends, as speculated to occur in beaked whales 
exposed to sonar. However, there is no specific evidence of this upon 
exposure to airgun pulses.
    In general, very little is known about the potential for seismic 
survey sounds (or other types of strong underwater sounds) to cause 
non-auditory physical effects in marine mammals. Such effects, if they 
occur at all, would presumably be limited to short distances and to 
activities that extend over a prolonged period. The available data do 
not allow identification of a specific exposure level above which non-
auditory effects can be expected (Southall et al., 2007), or any 
meaningful quantitative predictions of the numbers (if any) of marine 
mammals that might be affected in those ways. Marine mammals that show 
behavioral avoidance of seismic vessels, including most baleen whales 
and some odontocetes, are especially unlikely to incur non-auditory 
physical effects.

Potential Effects of Other Acoustic Devices

MBES
    L-DEO will operate the Kongsberg EM 122 MBES from the source vessel 
during the planned study. Sounds from the MBES are very short pulses, 
occurring for two to 15 ms once every five to 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 to 2[deg]) in fore-aft extent and

[[Page 26268]]

wide (150[deg]) in the cross-track extent. Each ping consists of eight 
(in water greater than 1,000 m deep) or four (in water less than 1,000 
m 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 
to 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 an 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 L-DEO's operations, 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 
an MBES on marine mammals are outlined below.
    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 (Globicephala melas) 
(Rendell and Gordon, 1999), and the previously-mentioned beachings by 
beaked whales. During exposure to a 21 to 25 kHz ``whale-finding'' 
sonar with a source level of 215 dB re 1 [micro]Pa, gray whales reacted 
by orienting slightly away from the source and being deflected from 
their course by approximately 200 m (Frankel, 2005). When a 38 kHz 
echosounder and a 150 kHz acoustic Doppler current profiler 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 L-DEO, 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 an 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, 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 by L-DEO 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.
    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.
SBP
    L-DEO will also operate a SBP from the source vessel during the 
proposed survey. Sounds from the SBP are very short pulses, occurring 
for one to four 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 [mu]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 an 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 will move away in response to the approaching higher-
power sources or the vessel itself before

[[Page 26269]]

the mammals would be close enough for there to be any possibility of 
effects from the less intense sounds from the SBP.
Acoustic Release Signals
    The acoustic release transponder used to communicate with the OBSs 
uses frequencies 9 to 13 kHz. These signals will be used very 
intermittently. It is unlikely that the acoustic release signals would 
have a significant effect on marine mammals through masking, 
disturbance, or hearing impairment. Any effects likely would be 
negligible given the brief exposure at presumably low levels.
    The potential effects to marine mammals described in this section 
of the document do not take into consideration the proposed monitoring 
and mitigation measures described later in this document (see the 
``Proposed Mitigation'' and ``Proposed Monitoring and Reporting'' 
sections) which, as noted are designed to effect the least practicable 
adverse impact on affected marine mammal species and stocks.

Anticipated Effects on Marine Mammal Habitat

    The proposed seismic survey will not result in 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), and 
there will be no physical damage to any habitat. 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.
    A total of approximately 21 OBSs will be deployed during the 
proposed study. Scripps LC4x4 OBSs will be used; this type of OBS has a 
volume of approximately 1 m \3\, with an anchor that consists of a 
large piece of steel grating (approximately 1 m \2\). OBS anchors will 
be left behind upon equipment recovery. Although OBS placement will 
disrupt a very small area of seafloor habitat and could disturb benthic 
invertebrates, the impacts are expected to be localized and transitory.

Anticipated Effects on Fish

    One reason for the adoption of airguns as the standard energy 
source for marine seismic surveys is that, unlike explosives, they have 
not been associated with large-scale fish kills. However, existing 
information on the impacts of seismic surveys on marine fish 
populations is limited (see Appendix D of L-DEO'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 D L-DEO'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 L-DEO and NMFS know, there are only two papers with proper 
experimental methods, controls, and careful pathological investigation 
implicating sounds produced by actual seismic survey airguns in causing 
adverse anatomical effects. One such study indicated anatomical damage, 
and the second indicated TTS in fish hearing. The anatomical case is 
McCauley et al. (2003), who found that exposure to airgun sound caused 
observable anatomical damage to the auditory maculae of pink snapper 
(Pagrus auratus). This damage in the ears had not been repaired in fish 
sacrificed and examined almost two months after exposure. On the other 
hand, Popper et al. (2005) documented only TTS (as determined by 
auditory brainstem response) in two of three fish species from the 
Mackenzie River Delta. This study found that broad whitefish (Coregonus 
nasus) exposed to five airgun shots were not significantly different 
from those of controls. During both studies, the repetitive exposure to 
sound was greater than would have occurred during a typical seismic 
survey. However, the substantial low-frequency energy produced by the 
airguns [less than 400 Hz in the study by McCauley et al. (2003) and 
less than approximately 200 Hz in Popper et al. (2005)] likely did not 
propagate to the fish because the water in the study areas was very 
shallow (approximately nine m in the former case and less than two m in 
the latter). Water depth sets a lower limit on the lowest sound 
frequency that will propagate (the ``cutoff frequency'') at about one-
quarter wavelength (Urick, 1983; Rogers and Cox, 1988).
    Wardle et al. (2001) suggested that in water, acute injury and 
death of organisms exposed to seismic energy depends primarily on two 
features of the sound source: (1) The received peak pressure and (2) 
the time required for the pressure to rise and decay. Generally, as 
received pressure

[[Page 26270]]

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 D of L-DEO'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 followed by habituation and a return to normal 
behavior after the sound ceased.
    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 Fisheries

    It is possible that the Langseth's streamers may become entangled 
with various types of fishing gear. Salmon, cod, rockfish, and 
sablefish fisheries will be operating at the time of the seismic 
project in the western GOA (ADF&G, 2010). L-DEO will employ avoidance 
tactics as necessary to prevent conflict. It is not expected that L-
DEO's operations will have a significant impact on commercial fisheries 
in the western GOA. Nonetheless, L-DEO will minimize the potential to 
have a negative impact on the fisheries by avoiding areas where fishing 
is actively underway.
    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 
(CPUE) 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).

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 E of L-DEO'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 E of L-DEO'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.

[[Page 26271]]

    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).

Proposed Mitigation

    In order to issue an Incidental Take Authorization (ITA) under 
Section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible 
methods of taking pursuant to such activity, and other means of 
effecting the least practicable adverse impact on such species or stock 
and its habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance, and the availability of 
such species or stock for taking for certain subsistence uses.
    L-DEO has based the 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;
    (2) Previous IHA applications and IHAs approved and authorized by 
NMFS; and
    (3) Recommended best practices in Richardson et al. (1995), Pierson 
et al. (1998), and Weir and Dolman, (2007).
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, L-DEO 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;
    (4) Ramp-up procedures; and
    (5) Special procedures for situations and species of concern.
    Planning Phase--The PIs worked with L-DEO and NSF to identify 
potential time periods to carry out the survey taking into 
consideration key factors such as environmental conditions (i.e., the 
seasonal presence of marine mammals, sea turtles, and sea birds), 
weather conditions, and equipment. The survey was previously scheduled 
for September, 2010; however after further consideration, it was viewed 
as not a viable operational option because of the strong possibility of 
not being able to carry out the science mission under potential weather 
conditions in the region at that time of year. Also, the late June to 
early August cruise avoids the peak in humpback abundance (late August 
to early September) and the peak of the marine mammal harvest 
(generally September to December, with a reduction in hunting effort in 
summer).
    Reducing the size of the energy source was also considered, but it 
was decided that the 6,600 in\3\, 36 airgun array is necessary to 
penetrate through the seafloor to accurately delineate the geologic 
features and to achieve the primary scientific objectives of the 
program. A large source that is rich in relatively low-frequency 
seismic energy is required to penetrate to depths greater than 20 to 30 
km (10.8 to 16.2 nmi) and image the deep fault that causes earthquakes 
off Alaska. By towing this source configuration at 12 m below the sea 
surface, the lower frequencies are enhanced. If a smaller source were 
used, it would inhibit the deep imaging of the fault zone, thus 
preventing the scientists' ability to carry out their research as 
proposed and meet their objectives. Similarly, the proposed combination 
of OBSs and hydrophone streamers are needed to record seismic returns 
from deep in the earth and determine the depth and geometry of the 
fault zone, thus meeting the scientific objectives.
    Proposed Exclusion Zones--Received sound levels have been 
determined by empirical corrected measurements for the 36 airgun array, 
and a L-DEO model was used to predict the EZs for the single 1900LL 40 
in\3\ airgun, which will be used during power-downs. Results were 
recently reported for propagation measurements of pulses from the 36 
airgun array in two water depths (approximately 1,600 m and 50 m [5,249 
to 164 ft]) in the Gulf of Mexico in 2007 to 2008 (Tolstoy et al., 
2009). It would be prudent to use the empirical values that resulted to 
determine EZs for the airgun array. Results of the propagation 
measurements (Tolstoy et al., 2009) showed that radii around the 
airguns for various received levels varied with water depth. As no 
measurements were made in intermediate depth water, values halfway 
between the deep and shallow-water measurements were used. In addition, 
propagation varies with array tow depth. The depth of the array was 
different in the Gulf of Mexico calibration study (6 m [19.7 ft]) than 
in the proposed survey in the GOA (12 m); thus, correction factors have 
been applied to the distances reported by Tolstoy et al. (2009). The 
correction factors used were the ratios of the 160, 180, and 190 dB 
distances from the modeled results for the 6,600 in\3\ airgun array 
towed at 6 m versus 12 m.
    Measurements were not reported for a single airgun, so model 
results will be used. The L-DEO model does not allow for bottom 
interactions, and thus is most directly applicable to deep water and to 
relatively short ranges. A detailed

[[Page 26272]]

description of the modeling effort is predicted in Appendix A of the 
EA.
    Based on the corrected propagation measurements (airgun array) and 
modeling (single airgun), the distances from the source where sound 
levels are predicted to be 190, 180, and 160 dB re 1 [micro]Pa (rms) 
were determined (see Table 1 above). The 180 and 190 dB radii are shut-
down criteria applicable to cetaceans and pinnipeds, respectively, as 
specified by NMFS (2000); these levels were used to establish the EZs. 
If the 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.
    Power-down Procedures--A power-down involves decreasing the number 
of airguns in use to one airgun, 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, 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, L-DEO will power-down the airguns before the 
animal is within the EZ. Likewise, if a mammal is already within the 
EZ, when first detected L-DEO will power-down the airguns immediately. 
During a power-down of the airgun array, L-DEO 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), L-DEO will shut-down the airgun 
(see next section).
    Following a power-down, L-DEO will not resume airgun activity until 
the marine mammal has cleared the EZ. 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 and large odontocetes, including sperm, killer, and beaked 
whales).
    During airgun operations following a power-down (or shut-down) 
whose duration has exceeded the time limits specified previously, L-DEO 
will ramp-up the airgun array gradually (see Shut-down and Ramp-up 
Procedures).
    Shut-down Procedures--L-DEO will shut down the operating airgun(s) 
if a marine mammal is seen within or approaching the EZ for the single 
airgun. L-DEO will implement a shut-down:
    (1) If an animal enters the EZ of the single airgun after L-DEO has 
initiated a power-down; 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.
    L-DEO will 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.
    Ramp-up Procedures--L-DEO will 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. USGS proposes 
that, for the present cruise, this period would be approximately nine 
min. This period is based on the 180 dB radius (1,100 m) for the 36 
airgun array towed at a depth of 12 m in relation to the minimum 
planned speed of the Langseth while shooting (7.4 km/hr). 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 six dB per five min 
period over a total duration of approximately 35 min. During ramp-up, 
the Protected Species Observers (PSOs) will monitor the EZ, and if 
marine mammals are sighted, 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, L-DEO will 
not commence the ramp-up 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 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. L-DEO will not initiate a ramp-up of the 
airguns if a marine mammal is sighted within or near the applicable EZs 
during the day or close to the vessel at night.
    Special Procedures for Situations and Species of Concern--L-DEO 
will implement special mitigation procedures as follows:
     The airguns will be shut-down immediately if ESA-listed 
species for which no takes are being requested (i.e., North Pacific 
right, sei, blue, and beluga whales) are sighted at any distance from 
the vessel. Ramp-up will only begin if the whale has not been seen for 
30 min.
     Concentrations of humpback, fin, and/or killer whales will 
be avoided if possible, and the array will be powered-down if 
necessary. For purposes of this proposed survey, a concentration or 
group of whales will consist of three or more individuals visually 
sighted that do not appear to be traveling (e.g., feeding, socializing, 
etc.).
     Seismic operations in Chignik Bay will be conducted from 
nearshore to offshore waters.
     Avoidance of areas where subsistence fishers are fishing, 
if requested (or viewed as necessary).
    NMFS has carefully evaluated the applicant's proposed mitigation 
measures and has considered a range of other measures in the context of 
ensuring that NMFS prescribes the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. NMFS's evaluation of potential measures 
included consideration of the following factors in relation to one 
another:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure is expected to minimize adverse impacts 
to marine mammals;
    (2) The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned; and
    (3) The practicability of the measure for applicant implementation.
    Based on NMFS's evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS or recommended by the public, 
NMFS has preliminarily determined that the proposed mitigation measures 
provide the means of effecting the least practicable adverse impacts on 
marine mammal species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

[[Page 26273]]

Proposed Monitoring and Reporting

    In order to issue an ITA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth ``requirements pertaining to 
the monitoring and reporting of such taking.'' The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for IHAs 
must include the suggested means of accomplishing the necessary 
monitoring and reporting that will result in increased knowledge of the 
species and of the level of taking or impacts on populations of marine 
mammals that are expected to be present in the action area.

Monitoring

    L-DEO 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. L-DEO's proposed 
Monitoring Plan is described below this section. L-DEO understands that 
this monitoring plan will be subject to review by NMFS, and that 
refinements may be required. The monitoring work described here has 
been planned as a self-contained project independent of any other 
related monitoring projects that may be occurring simultaneously in the 
same regions. L-DEO 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 (i.e., greater than 
approximately 9 min for this proposed cruise). When feasible, 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. The EZ is a region in which a possibility exists of 
adverse effects on animal hearing or other physical effects.
    During seismic operations in the western GOA, at least four PSOs 
(PSVO and/or PSAO) will be based aboard the Langseth. L-DEO will 
appoint the PSOs with NMFS's concurrence. Observations will take place 
during ongoing daytime operations and nighttime ramp-ups of the 
airguns. During the majority of seismic operations, 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 hrs.
    Two PSVOs will also be on visual watch during all nighttime ramp-
ups of the seismic airguns. A third PSAO will monitor the 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 PSAO on PAM. 
Other crew will also be instructed to assist in detecting marine 
mammals and implementing mitigation requirements (if practical). Other 
crew will also be instructed to assist in detecting marine mammals and 
implementing mitigation requirements. 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 PSVO(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 and large odontocetes, including 
sperm, killer, and beaked whales).

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. Acoustical monitoring can be used in addition to 
visual observations to improve detection, identification, and 
localization of cetaceans. The acoustic monitoring will serve to alert 
visual observers (if on duty) when vocalizing cetaceans 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 
cetaceans are detected.
    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 tow cable is 
250 m (820.2 ft) long, and the hydrophones are fitted in the last 10 m 
(32.8 ft) of cable. A depth gauge is attached to the free end of the 
cable, and the cable is typically towed at depths less than 20 m (65.6 
ft). 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, signal conditioning, and 
processing system will be located. The acoustic signals received by the 
hydrophones are amplified, digitized, and then processed by the 
Pamguard software. The system can detect marine mammal vocalizations at 
frequencies up to 250 kHz.
    One Protected Species Acoustic Observer (PSAO, an expert 
bioacoustician in addition to the four PSVOs), with primary 
responsibility for PAM, will be onboard the Langseth. The towed 
hydrophones will ideally be monitored by the PSAO 24 hours per day 
while at the proposed seismic survey area during airgun operations, and 
during most periods when the Langseth is underway while the airguns

[[Page 26274]]

are not operating. However, PAM may not be possible if damage occurs to 
the array or back-up systems during operations. The primary PAM 
streamer on the Langseth is a digitial hydrophone streamer. Should the 
digital streamer fail, back-up systems should include an analog spare 
streamer and a hull-mounted hydrophone. One PSAO will monitor the 
acoustic detection system 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 cetaceans. The 
PSAO monitoring the acoustical data will be on shift for one to six 
hours at a time. All PSOs are expected to rotate through the PAM 
position, although the expert PSAO 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 cetaceans (if they have not already been seen), and 
to allow a power-down or shut-down to be initiated, if required. When 
bearings (primary and mirror-image) to calling cetacean(s) are 
determined, the bearings will be related to the PSVO(s) to help him/her 
sight the calling animal. 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. In addition to 
transits to, from, and through the study area, there will also be 
opportunities to collect baseline biological data during the deployment 
and recovery of OBSs.
    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.
    L-DEO 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.
    L-DEO will report all injured or dead marine mammals (regardless of 
cause) to NMFS as soon as practicable. The report should include the 
species or description of the animal, the condition of the animal, 
location, time first found, observed behaviors (if alive) and photo or 
video, if available. In the unanticipated event that any taking of a 
marine mammal in a manner prohibited by the proposed IHA occurs, such 
as an injury, serious injury, or mortality, and is judged to result 
from the proposed activities, the operator will immediately report the 
incident to the Chief of the Permits, Conservation, and Education 
Division, Office of Protected Resources, NMFS. The operator will 
postpone the proposed activities until NMFS is able to review the 
circumstances of the take. NMFS will work with the operator to 
determine whether modifications in the activities are appropriate and 
necessary, and notify the operator that they may resume sound source 
operations.

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 geophysical survey in the 
western GOA. 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. There is no evidence that the planned activities could 
result in injury, serious injury, or mortality within the specified 
geographic area for which L-DEO seeks the IHA. The required mitigation 
and monitoring measures will minimize any potential risk for injury, 
serious injury, or mortality.

[[Page 26275]]

    The following sections describe L-DEO'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 36 airgun array to be used during approximately 
2,553 km of survey lines in the western GOA.
    L-DEO assumes that, during simultaneous operations of the airgun 
array and the other sources, any marine mammals close enough to be 
affected by the MBES and SBP 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 and SBP given 
their characteristics (e.g., narrow, downward-directed beam) and other 
considerations described previously. Such reactions are not considered 
to constitute ``taking'' (NMFS, 2001). Therefore, L-DEO provides no 
additional allowance for animals that could be affected by sound 
sources other than airguns.
    There are several sources of systematic data on the numbers and 
distributions of marine mammals in the coastal and nearshore areas of 
the GOA, but there are fewer data for offshore areas. Zerbini et al. 
(2003, 2006, 2007) conducted vessel-based surveys in the northern and 
western GOA from the Kenai Peninsula to the central Aleutian Islands 
during July to August 2001 to 2003. These surveys included all of the 
coastal and nearshore areas of the currently proposed study area. 
Killer whales were the principal target of the surveys, but the 
abundance and distribution of fin, humpback, and minke whales were also 
reported. Waite (2003) conducted vessel-based surveys in the northern 
and western GOA from Prince William Sound to approximately 160[deg] 
West off the Alaska Peninsula during June 26 to July 15, 2003 (Waite, 
2003); cetaceans recorded included small odontocetes, beaked whales, 
and mysticetes. The eastern part of the surveys by Zerbini et al. were 
confined to waters less than 1,000 m deep with most effort in depths 
less than 100 m, and all of Waite's survey was confined to waters less 
than 1,000 m deep with most effort in depths 100 to 1,000 m.
    Dahlheim et al. (2000) conducted aerial surveys of the nearshore 
waters from Bristol Bay to Dixon Entrance for harbor porpoises; 
southeast Alaska was surveyed during June 1 to 26, 1993. Dahlheim and 
Towell (1994) conducted vessel-based surveys of Pacific white-sided 
dolphins in the inland waterways of Southeast Alaska during April to 
May, June or July, and September to early October of 1991 to 1993. In a 
report on a seismic cruise in southeast Alaska from Dixon Entrance to 
Kodiak Island during August to September, 2004, MacLean and Koski 
(2005) included density estimates of cetaceans and pinnipeds for each 
of three depth ranges (<100 m, 100 to 1,000 m, and >1,000 m) during 
non-seismic periods. Hauser and Holst (2009) reported density estimates 
during non-seismic periods for all marine mammals sighted during a 
September to early October seismic cruise in southeast Alaska for each 
of the same three depth ranges as MacLean and Koski (2005). Rone et al. 
(2010) conducted surveys of the nearshore and offshore GOA during 
April, 2009 and provided estimates of densities of humpback and fin 
whales and provided maps with sightings of other species.
    Most surveys for pinnipeds in Alaska waters have estimated the 
number of animals at haul-out sites, not in the water (e.g., Loughlin, 
1994; Sease et al., 2001; Withrow and Cesarone, 2002; Sease and York, 
2003). The Department of the Navy (DON) (2009) estimated monthly in-
water densities of several species of pinnipeds in the offshore GOA 
based on shore counts and biological (mostly breeding) information. To 
our knowledge, the only direct information available on at-sea 
densities of pinnipeds in and near the proposed survey area was 
provided by MacLean and Koski (2005) and Hauser and Holst (2009).
    Table 2 (Table 5 of the EA) gives the estimated average (best) and 
maximum densities of marine mammals expected to occur in the waters of 
the central and western GOA. L-DEO used the densities reported by 
MacLean and Koski (2005) and Hauser and Holst (2009), and those 
calculated from effort and sightings in Dahlheim and Towell (1994) and 
Waite (2003) have been corrected for both detectability and 
availability bias using correction factors from Dahlheim et al. (2000) 
and Barlow and Forney (2007). Detectability bias is associated with 
diminishing sightability with increasing lateral distance from the 
trackline. Availability bias refers to the fact that there is less-
than-100% probability of sighting an animal that is present along the 
survey trackline [fnof](0), and it is measured by g(0).
    Table 2 (Table 5 of the EA) incorporates the densities from the 
aforementioned studies plus those from the following surveys. L-DEO 
included the killer whale and mysticete densities from the easternmost 
blocks surveyed by Zerbini et al. (2006, 2007), and the harbor porpoise 
densities for the Kodiak and Alaska Peninsula survey areas from Table 3 
of Dahlheim and Towell (1994). Maps of effort and sightings in Waite 
(2003) and Zerbini et al. (2006, 2007) were used to roughly allocate 
effort and sightings between water less than 100 m and 100 to 1,000 m 
deep. Offshore effort and maps of sightings in the offshore stratum of 
Rone et al. (2010) were used to calculate densities for water depths 
greater than 1,000 m. Densities of Steller sea lion, northern fur 
seals, and northern elephant seals in water depths greater than 1,000 m 
were taken from DON (2009; Appendix E, Table 5) for July, and those in 
water depths less than 1,000 m are from MacLean and Koski (2005) and 
Hauser and Holst (2009).
    There is some uncertainty about the representativeness of the data 
and the assumptions used in the calculations below for three main 
reasons:
    (1) The timing of most of the survey effort (17,806 km [9,614.5 
nmi]) (i.e., one of the surveys of Dahlheim and Towell [1994] and the 
surveys of Dahlheim et al. (2000), Waite [2003], MacLean and Koski 
(2005), and Zerbini et al. [2006, 2007]) overlaps the timing of the 
proposed survey, but some survey effort (4,693 km [2,534 nmi])--(i.e., 
two of the surveys of Dahlheim and Towell [1994] and the surveys of 
Rone et al. [2010] and Hauser and Holst [2009]) was earlier (April or 
June) or later (September to October) than the proposed July to August 
survey;
    (2) Surveys by MacLean and Koski (2005), Hauser and Holst (2009), 
and Dahlheim and Towell (1994) were conducted primarily in southeast 
Alaska (east of the proposed study area); and
    (3) Only the McLean and Koski (2005), Hauser and Holst (2009), and 
Rone et al. (2010) surveys included depths greater than 1,000 m, 
whereas approximately 53% of the proposed line-km are in water depths 
greater than 1,000 m. However, the densities are based on a 
considerable survey effort (22,500 km [12,149 nmi], including 17,806 km 
[9,614.5 nmi] in months that overlap the proposed survey period), and 
the approach used here is believed to be the best available approach.
    Also, to provide some allowance for these uncertainties, ``maximum 
estimates'' as well as ``best estimates'' of the densities present and 
numbers potentially affected have been derived. Best estimates of 
density are effort-weighted mean densities from all previous surveys, 
whereas maximum estimates of density come from the individual survey 
that provided the

[[Page 26276]]

highest density. For pinnipeds in deep water where only one density was 
available (DON, 2009), that density was used as the best estimate and 
the maximum is 1.5x the best estimate.
    For one species, the Dall's porpoise, density estimates in the 
original reports are much higher than densities expected during the 
proposed survey, because this porpoise is attracted to vessels. L-DEO 
estimates for Dall's porpoises are from vessel-based surveys without 
seismic activity; they are overestimates possibly by a factor of 5x, 
given the tendency of this species to approach vessels (Turnock and 
Quinn, 1991). Noise from the airgun array during the proposed survey is 
expected to at least reduce and possibly eliminate the tendency of this 
porpoise to approach the vessel. Dall's porpoises are tolerant of small 
airgun sources (MacLean and Koski, 2005) and tolerated higher sound 
levels than other species during a large-array survey (Bain and 
Williams, 2006); however, they did respond to that and another large 
airgun array by moving away (Calambokidis and Osmek, 1998; Bain and 
Williams, 2006). Because of the probable overestimates, the best and 
maximum estimates for Dall's porpoises shown in Table 2 (Table 3 of the 
IHA application) are one-quarter of the reported densities. In fact, 
actual densities are probably slightly lower than that.
    L-DEO's estimates of exposures to various sound levels assume that 
the proposed surveys will be fully completed including the contingency 
line; in fact, the ensonified areas calculated using the planned number 
of line-km have been increased by 25% to accommodate 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. Furthermore, 
any marine mammal sightings within or near the designated EZs will 
result in the power-down or shut-down of seismic operations as a 
mitigation measure. Thus, the following estimates of the numbers of 
marine mammals potentially exposed to sound levels of 160 dB re 1 
[mu]Pa (rms) are precautionary and probably overestimate the actual 
numbers of marine mammals that might be involved. These estimates also 
assume that there will be no weather, equipment, or mitigation delays, 
which is highly unlikely.
    L-DEO 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. Thus, few individual marine mammals would be 
exposed more than once during the survey. Moreover, it is unlikely that 
a particular animal would stay in the area during the entire survey.
    For each depth stratum, the number of different individuals 
potentially exposed to received levels greater than or equal to 160 re 
1 [mu]Pa (rms) was calculated by multiplying:
    (1) The expected species density, either ``mean'' (i.e., best 
estimate) or ``maximum'', times
    (2) The anticipated area to be ensonified to that level during 
airgun operations excluding overlap.
    The area expected to be ensonified was determined by entering the 
planned survey lines into a MapInfo GIS, using the GIS to identify the 
relevant areas by ``drawing'' the applicable 160 dB buffer (see Table 1 
of the IHA application) around each seismic line, and then calculating 
the total area within the buffers. 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.
    Applying the approach described above, approximately 49,679 km\2\ 
(14,841.1 nmi\2\) (approximately 62,098 km\2\ [18,104.9 nmi\2\] 
including the 25% contingency) would be within the 160 dB isopleth on 
one or more occasions during the survey. For less than 100 m, 100 to 
1,000 m, and greater than 1,000 m depth ranges, the areas would be 
32,451 km\2\ (9,487.4 nmi\2\) (40,564 km\2\ [11,826.6 nmi\2\] including 
the 25% contingency), 8,612 km\2\ (2,510.9 nmi\2\) (10,765 km\2\ 
[3,138.6 nmi\2\]), and 8,616 km\2\ (2,512 nmi\2\) (10,769 km\2\ 
[3,139.7 nmi\2\]), respectively. Because this approach does not allow 
for turnover in the marine 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 conservative (i.e., 
probably overestimated) densities used to calculate the numbers exposed 
may offset this. In addition, the approach assumes that no cetaceans 
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.
    Table 3 (Table 4 of the IHA application) shows the best and maximum 
estimates of the number of different individual marine mammals that 
potentially could be exposed to greater than or equal to 160 dB re 1 
[mu]Pa (rms) during the seismic survey if no animals moved away from 
the survey vessel. The requested take authorization, given in Table 3 
(the far right column of Table 4 of the IHA application), is based on 
the best estimates rather than the maximum estimates of the numbers 
exposed, because there was little uncertainty associated with the 
method of estimating densities. For cetacean species not listed under 
the ESA that could occur in the study area but were not sighted in the 
surveys from which density estimates were calculated--gray whale, 
Risso's dolphin, short-finned pilot whale, and Stejneger's beaked 
whale--the average group size has been used to request take 
authorization. For ESA-listed cetacean species unlikely to be 
encountered during the study (North Pacific right, sei, blue, and 
beluga whales), the requested takes are zero.
    The ``best estimate'' of the number of individual cetaceans that 
could be exposed to seismic sounds with received levels greater than or 
equal to 160 dB re 1 [mu]Pa (rms) during the proposed survey is 4,392 
(see Table 4 of the IHA application) for all three depth ranges 
combined. That total includes 1,824 humpback whales, 60 minke whales, 
598 fin whales, 5 sperm whales, 12 Cuvier's beaked whales, 4 Baird's 
beaked whales, 127 Pacific white-sided dolphins, 415 killer whales, and 
180 harbor porpoises which would represent 8.7%, 0.2%, 3.7%, 0.1%, 
0.1%, 0.1%, 0.1%, 4.9%, and 0.1% of the regional populations, 
respectively. After humpback whales, Dall's porpoises are expected to 
be the most common species in the study area; the best estimate of the 
number of Dall's porpoises that could be exposed is 1,167 or about 0.1% 
of the regional population. This may be a slight overestimate because 
the estimated densities are slight overestimates. Estimates for other 
species are lower. The ``maximum estimates'' total 12,625 cetaceans for 
the three depth ranges combined.

[[Page 26277]]

    ``Best estimates'' of 270 Steller sea lions and 218 harbor seals 
could be exposed to airgun sounds with received levels greater than or 
equal to 160 dB re 1 [mu]Pa (rms). These estimates represent 0.3% of 
the Steller sea lion regional population and less than 0.1% of the 
harbor seal regional population. The estimated numbers of pinnipeds 
that could be exposed to received levels greater than or equal to 160 
dB re 1 [mu]Pa (rms) are probably overestimates of the actual numbers 
that will be affected. Northern fur seals and northern elephant seals 
are at their rookeries in August. No take has been requested for North 
Pacific right, sei, and blue whales, beluga whales, Northern elephant 
seals, Northern fur seals, or California sea lions because they are 
unlikely to be encountered in the proposed study area.

 Table 3--Estimates of the Possible Numbers of Marine Mammals Exposed to Different Sound Levels >= 160 dB During
                 L-DEO's Proposed Seismic Survey in the Western GOA During June to August, 2011
----------------------------------------------------------------------------------------------------------------
                              Estimated number of  Estimated number of
                              individuals exposed  individuals exposed                       Approximate percent
           Species             to sound levels >=   to sound levels >=     Requested take        of regional
                               160 dB re 1 [mu]Pa   160 dB re 1 [mu]Pa     authorization        population\2\
                                   (Best\1\)           (Maximum\1\)                                 (Best)
----------------------------------------------------------------------------------------------------------------
Mysticetes:
    North Pacific right                         0                    0                    0                  0
     whale..................
    Gray whale..............                   NA                   NA                \3\ 6                 NA
    Humpback whale..........                1,824                3,458                1,824                  8.8
    Minke whale.............                   60                  308                   60                  0.2
    Sei whale...............                    0                    0                    0                  0
    Fin whale...............                  598                2,166                  598                  3.7
    Blue whale..............                    0                    0                    0                  0
Odontocetes:
    Sperm whale.............                    5                   21                    5                < 0.1
    Cuvier's beaked whale...                   12                   19                   12                  0.1
    Baird's beaked whale....                    4                    6                    4                  0.1
    Stejneger's beaked whale                    0                    0               \3\ 15                  0
    Beluga whale............                    0                    0                    0                  0
    Pacific white-sided                       127                  348                  127                < 0.1
     dolphin................
    Risso's dolphin.........                    0                    0               \3\ 33                  0
    Killer whale............                  415                2,292                  415                  4.9
    Short-finned pilot whale                    0                    0               \3\ 50                 NA
    Harbor porpoise.........                  180                2,050                  180                  0.1
    Dall's porpoise.........                1,167                1,957                1,167                  0.1
Pinnipeds
    Northern fur seal.......                    0                    0                    0                  0
    Steller sea lion........                  270                  365                  270                  0.3
    California sea lion.....                   NA                   NA                   NA                 NA
    Harbor seal.............                  218                  299                  218                  0.1
    Northern elephant seal..                    0                    0                    0                  0
----------------------------------------------------------------------------------------------------------------
\1\ Best and maximum estimates are based on densities from Table 3 (Table 4 of the IHA application) and
  ensonified areas (including 25% contingency) for 160 dB of 40,564 km\2\, 10,765 km\2\, and 10,770 km\2\ for
  <100 m, 100 to 1,000 m, and >1,000 m depth ranges, respectively.
\2\ Regional population size estimates are from Table 2 (see Table 2 of the IHA application); NA means not
  available.
\3\ Requested takes for species not sighted in surveys from which densities were derived are based on group
  size.

Encouraging and Coordinating Research

    L-DEO and NSF will coordinate the planned marine mammal monitoring 
program associated with the seismic survey in the western GOA with 
other parties that may have an interest in the area and/or be 
conducting marine mammal studies in the same region during the proposed 
seismic survey. L-DEO and NSF will coordinate with applicable U.S. 
Federal, State, and Borough agencies, and will comply with their 
requirements. Actions of this type that are underway include (but are 
not limited to) the following:
     Coordination with the Alaska Department of Fish and Game 
concerning fisheries issues in state waters.
     Contact Alaska Native Harbor Seal Commission, the Aleut 
Marine Mammal Commission, and the Alaska Sea Otter and Steller Sea Lion 
Commission with regard to potential concerns about interactions with 
fisheries and subsistence hunting.
     Contact USFWS regarding concerns about possible impacts on 
sea otters and critical habitat (for ESA).
     Contact USFWS avian biologists (Kathy Kuletz and Tim 
Bowman) regarding potential interaction with seabirds (for ESA).
     Contact Mike Holley, U.S. Army Corps of Engineers (ACOE), 
to confirm that no permits will be required by the ACOE for the 
proposed survey.
     A Coastal Project Questionnaire and Certification 
statement will be submitted with a copy of the EA to the State of 
Alaska to confirm that the project is in compliance with state and 
local Coastal Management Programs.
     Contact the National Weather Service (NWS; Jack Endicott) 
about the survey with regard to the location of NWS buoys in the survey 
area and the proposed tracklines.
     Contact the logistics coordinator of the local commercial 
fish processor, to ensure that there will be minimal interference with 
the local salmon fishery.

Negligible Impact and Small Numbers Analysis and 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.''
    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

[[Page 26278]]

mitigation and monitoring measures, NMFS, on behalf of the Secretary, 
preliminarily finds that L-DEO's activities would result in the 
incidental take of marine mammals, by Level B harassment only, and that 
the total taking from the marine seismic survey in the western GOA 
would have a negligible impact on the affected species or stocks of 
marine mammals.
    For reasons stated previously in this document, the specified 
activities associated with the marine seismic survey are not likely to 
cause TTS, PTS, or other non-auditory injury, serious injury, or death, 
and no such take is anticipated or proposed to be authorized, and the 
potential for temporary or permanent hearing impairment is very low and 
will be minimized through the incorporation of the proposed monitoring 
and mitigation measures.
    In making a negligible impact determination, NMFS evaluated factors 
such as:
    (1) The number of anticipated injuries, serious injuries, or 
mortalities;
    (2) The number, nature, and intensity, and duration of Level B 
harassment (all relatively limited); and
    (3) The context in which the takes occur (i.e., impacts to areas of 
significance, impacts to local populations, and cumulative impacts when 
taking into account successive/contemporaneous actions when added to 
baseline data);
    (4) The status of stock or species of marine mammals (i.e., 
depleted, not depleted, decreasing, increasing, stable, impact relative 
to the size of the population);
    (5) Impacts on habitat affecting rates of recruitment/survival; and
    (6) The effectiveness of monitoring and mitigation measures.
    As mentioned previously, NMFS estimates that 16 species of marine 
mammals under its jurisdiction could be potentially affected by Level B 
harassment over the course of the IHA. For each species, these numbers 
are small (each, one percent or less, except for humpback [8.8%], fin 
[3.7%], and killer [4.9%] whales) relative to the regional population 
size.
    No injuries, serious injuries, or mortalities are anticipated to 
occur as a result of the L-DEO's planned marine seismic survey, and 
none are proposed to be authorized. Only short-term behavioral 
disturbance is anticipated to occur due to the brief and sporadic 
duration of the survey 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.
    NMFS has preliminarily determined, provided that the aforementioned 
mitigation and monitoring measures are implemented, that the impact of 
conducting a marine geophysical survey in the western GOA, June to 
August, 2011, may result, at worst, in a temporary modification in 
behavior and/or low-level physiological effects (Level B harassment) of 
small numbers of certain species of marine mammals.
    While behavioral modifications, including temporarily vacating the 
area during the operation of the airgun(s), may be made by these 
species to avoid the resultant acoustic disturbance, the availability 
of alternate areas within these areas and the short and sporadic 
duration of the research activities, have led NMFS to preliminary 
determine that this action will have a negligible impact on the species 
in the specified geographic region.
    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 L-DEO's planned research 
activities, will result in the incidental take of small numbers of 
marine mammals, by Level B harassment only, and that the total taking 
from the marine seismic survey will have a negligible impact on the 
affected species or stocks.

Impact on Availability of Affected Species or Stock for Taking for 
Subsistence Uses

    Section 101(a)(5)(D) also requires NMFS to determine that the 
authorization will not have an unmitigable adverse effect on the 
availability of marine mammal species or stocks for subsistence use. 
There are no relevant subsistence uses of marine mammals in the study 
area (offshore waters of the western GOA) that implicate MMPA Section 
101(a)(5)(D).

Endangered Species Act

    Of the species of marine mammals that may occur in the proposed 
survey area, several are listed as endangered under the ESA, including 
the North Pacific right, humpback, sei, fin, blue, and sperm whales, as 
well as the Cook Inlet DPS of beluga whales and the western stock of 
Steller sea lions. The eastern stock of Steller sea lions is listed as 
threatened. Critical habitat for the North Pacific right whale and 
Steller sea lion is also found within the proposed survey area. 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 initiated formal 
consultation under Section 7 of the ESA with NMFS's Office of Protected 
Resources, Endangered Species Division, to obtain a Biological Opinion 
evaluating the effects of issuing the IHA on threatened and endangered 
marine mammals and, if appropriate, authorizing incidental take. NMFS 
will conclude formal Section 7 consultation prior to making a 
determination on whether or not to issue the IHA. If the IHA is issued, 
NSF and L-DEO, 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.

National Environmental Policy Act (NEPA)

    With its complete application, L-DEO provided NMFS a draft 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 L-DEO is entitled ``Environmental Assessment of a 
Marine Geophysical Survey by the R/V Marcus G. Langseth in the western 
Gulf of Alaska, July-August 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 L-DEO EA for consistency with the 
regulations published by the Council of Environmental Quality (CEQ) and 
NOAA Administrative Order 216-6, Environmental Review Procedures for 
Implementing the National Environmental Policy Act, adopt the L-DEO EA 
and make a decision of whether or not to issue a Finding of No 
Significant Impact (FONSI).

Proposed Authorization

    NMFS proposes to issue an IHA to L-DEO for conducting a marine 
geophysical survey in the western GOA, provided the previously 
mentioned mitigation, monitoring, and reporting requirements are 
incorporated. The duration of the IHA would not exceed one year from 
the date of its issuance.

Information Solicited

    NMFS requests interested persons to submit comments and information

[[Page 26279]]

concerning this proposed project and NMFS' preliminary determination of 
issuing an IHA (see ADDRESSES). Concurrent with the publication of this 
notice in the Federal Register, NMFS is forwarding copies of this 
application to the Marine Mammal Commission and its Committee of 
Scientific Advisors.

    Dated: May 2, 2011.
James H. Lecky,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2011-11152 Filed 5-5-11; 8:45 am]
BILLING CODE 3510-22-P