[Federal Register Volume 77, Number 20 (Tuesday, January 31, 2012)]
[Notices]
[Pages 4765-4787]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2012-2076]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA879


Takes of Marine Mammals Incidental to Specified Activities; 
Marine Geophysical Survey in the Northwest Pacific Ocean, March Through 
April 2012

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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[[Page 4766]]

SUMMARY: NMFS has received an application from Lamont-Doherty Earth 
Observatory (L-DEO), a part of Columbia University, for an Incidental 
Harassment Authorization (IHA) to take marine mammals, by harassment, 
incidental to conducting a marine geophysical survey in the northwest 
Pacific Ocean, March through April, 2012.

DATES: Comments and information must be received no later than March 1, 
2012.

ADDRESSES: Comments on the application should be addressed to P. 
Michael Payne, Chief, Permits and Conservation Division, Office of 
Protected Resources, National Marine Fisheries Service, 1315 East-West 
Highway, Silver Spring, MD 20910-3225. The mailbox address for 
providing email comments is [email protected]. NMFS is not responsible 
for email comments sent to addresses other than the one provided here. 
Comments sent via email, including all attachments, must not exceed a 
10-megabyte file size.
    All comments received are a part of the public record and will 
generally be 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.
    An electronic 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 following associated documents are also available at the same 
internet address: the National Science Foundation's (NSF) draft 
Environmental Analysis (EA) pursuant to Executive Order 12114. The EA 
incorporates an ``Environmental Assessment of a Marine Geophysical 
Survey by the R/V Marcus G. Langseth in the Northwest Pacific Ocean, 
March-April, 2012,'' prepared by LGL Limited, on behalf of NSF. 
Documents cited in this notice may be viewed, by appointment, during 
regular business hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Jeannine Cody, Office of Protected 
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Background

    Section 101(a)(5)(D) of the Marine Mammal Protection Act of 1972, 
as amended (MMPA; 16 U.S.C. 1361 et seq.) directs the Secretary of 
Commerce 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 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. NMFS must publish a notice in the Federal Register 
within 30 days of its determination to 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 October 31, 2011, from L-DEO for 
the taking by harassment, of marine mammals, incidental to conducting a 
marine geophysical survey in the northwest Pacific Ocean in 
international waters. Upon receipt of additional information, NMFS 
determined the application complete and adequate on December 23, 2011.
    L-DEO, with research funding from the U.S. National Science 
Foundation (NSF), plans to conduct the survey from March 24, 2012, 
through April 16, 2012. L-DEO received an IHA in 2010 to conduct the 
same specified activity in the same location. However, due to medical 
emergencies, L-DEO suspended its operations and was unable to complete 
the seismic survey. Thus, this 2011 survey will allow L-DEO to acquire 
data necessary to complete the abbreviated 2010 study.
    L-DEO plans to use one source vessel, the R/V Marcus G. Langseth 
(Langseth), a seismic airgun array and a single hydrophone streamer to 
conduct a geophysical survey at the Shatsky Rise, a large igneous 
plateau in the northwest Pacific Ocean. The proposed survey will 
provide data necessary to decipher the crustal structure of the Shatsky 
Rise; may address major questions of earth history, geodynamics, and 
tectonics; could impact the understanding of terrestrial magmatism and 
mantle convection; and may obtain data that could be used to improve 
estimates of regional earthquake occurrence and distribution. In 
addition to the operations of the seismic airgun array and hydrophone 
streamer, 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 30 species of marine mammals by Level B 
harassment. Take is not expected to result from the use of the MBES or 
the SBP for reasons discussed in this notice. Also, NMFS does not 
expect take to result from collision with the Langseth because it is a 
single vessel moving at

[[Page 4767]]

relatively slow speeds (4.6 knots (kts); 8.5 km per hr (km/h); 5.3 
miles (mi) per hour (mph)) during seismic acquisition within the 
survey, for a relatively short period of time. 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 on the Shatsky Rise is scheduled to 
commence on March 24, 2012 and end on April 16, 2012. The Langseth 
would depart from Yokohama, Japan on March 24, 2012 and transit to the 
survey area in the northwest Pacific Ocean, approximately 1,200 
kilometers (km) (745.6 miles (mi)) in international waters offshore of 
the east coast of Japan. At the conclusion of the survey activities, 
the Langseth proposes to arrive in Honolulu, Hawaii, on April 16, 2012. 
Some minor deviation from these dates is possible, depending on 
logistics, weather conditions, and the need to repeat some lines if 
data quality is substandard. Therefore, NMFS proposes to issue an 
authorization that is effective from March 24, 2012 to May 7, 2012.
    Geophysical survey activities will involve 3-D seismic 
methodologies to decipher the crustal structure of the Shatsky Rise. To 
obtain high-resolution, 2-D structures of the area's magmatic systems 
and thermal structures, the Langseth will deploy a 36-airgun array as 
an energy source and a 6-km-long (3.7 mi-long) hydrophone streamer. As 
the airgun array is towed along the survey lines, the hydrophone 
streamer will receive the returning acoustic signals and transfer the 
data to the vessel's on-board processing system.
    The proposed study (e.g., equipment testing, startup, line changes, 
repeat coverage of any areas, and equipment recovery) will require 
approximately 7 days (d) to complete approximately 1,216 km (755.6 mi) 
of transect lines. The Langseth will conduct additional seismic 
operations in the survey area associated with turns, airgun testing, 
and repeat coverage of any areas where the initial data quality is sub-
standard. Data acquisition will include approximately 168 hours (hr) of 
airgun operations (7 d x 24 hr).
    L-DEO, the Langseth's operator, will conduct all planned seismic 
data acquisition activities, with on-board assistance by the scientists 
who have proposed the study. The Principal Investigators for this 
survey are Drs. Jun Korenaga (Yale University, New Haven, CT) and 
William Sager (Texas A&M University, College Station, TX). The vessel 
will be self-contained, and the crew will live aboard the vessel for 
the entire cruise.

Description of the Specified Geographic Region

    L-DEO will conduct the proposed survey in international waters in 
the northwest Pacific Ocean. The study area will encompass an area on 
the Shatsky Rise bounded by approximately 33.5-36 degrees ([deg]) North 
by 156-161[deg] East (see Figure 1 in L-DEO's application). Water 
depths in the survey area range from approximately 3,000 to 5,000 
meters (m) (1.9 to 3.1 mi).

Vessel Specifications

    The Langseth, owned by NSF, is 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 vessel, which has a length of 71.5 m (235 feet (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 pounds, is powered by two 3,550 horsepower (hp) Bergen BRG-6 
diesel engines which drive two propellers. 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 will be approximately 4.6 kts (8.5 km/h; 5.3 mph) and the 
cruising speed of the vessel outside of seismic operations is 18.5 km/h 
(11.5 mph or 10 kts).
    The Langseth will tow the 36-airgun array, as well as the 
hydrophone streamer, along predetermined lines. 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 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\) at a tow depth of 9 m (29.5 
ft). The airguns are 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 dominant frequency components range from 
zero to 188 Hertz (Hz). The array configuration consists of four 
identical linear strings, with 10 airguns on each string; the first and 
last airguns will be spaced 16 m (52 ft) apart. Of the 10 airguns, nine 
will fire simultaneously while the tenth airgun will serve as a spare 
and will be turned on in case of failure of one of the other airguns. 
The Langseth will distribute the array across an area of approximately 
24 x 16 m (78.7 x 52.5 ft) and will tow the array approximately 140 m 
(459.3 ft) behind the vessel. The tow depth of the array will be 9 m 
(29.5 ft).
    During the multichannel seismic (MCS) survey, each airgun array 
will emit a pulse at approximately 20-second (s) intervals which 
corresponds to a shot interval of approximately 50 m (164 ft). During 
firing, the airguns will emit a brief (approximately 0.1 s) pulse of 
sound; during the intervening periods of operations, the airguns will 
be silent.

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

[[Page 4768]]

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 array used by L-DEO on the 
Langseth is 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 (Greene, 1997; McCauley et al., 1998, 
2000a). 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 NSF'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 because of the directional 
nature of the sound from the airgun array. Appendix B(3) of NSF's EA 
discusses the characteristics of the airgun pulses. NMFS refers the 
reviewers to the IHA 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. 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 and that sound propagation varied with array 
tow depth.
    L-DEO used the results from the Gulf of Mexico study to determine 
the algorithm for its model that calculates the exclusion zones (EZ) 
for the 36-airgun array and the single airgun. L-DEO uses these values 
to designate mitigation zones and to estimate take (described in 
greater detail in Section VII of L-DEO's application and Section IV of 
NSF's EA) for marine mammals.
    Comparison of the Tolstoy et al. calibration study with L-DEO's 
model for the Langseth's 36-airgun array indicated that the model 
represents the actual received levels, within the first few kilometers, 
where the predicted EZs are located. However, the model for deep water 
(greater than 1,000 m; 3,280 ft) overestimated the received sound 
levels at a given distance but is still valid for defining exclusion 
zones at various tow depths. Because the tow depth of the array in the 
calibration study is less shallow (6 m; 19.7 ft) than the tow depth 
array in the proposed survey (9 m; 29.5 ft), L-DEO used correction 
factors for estimating the received levels in deep water during the 
proposed survey. 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 (19.7 ft) versus 9 m (29.5 ft) from LGL 
(2008); 1.285, 1.338, and 1.364 respectively. For a single airgun, the 
tow depth has minimal effect on the maximum near-field output and the 
shape of the frequency spectrum for the single airgun; thus, the 
predicted EZs are essentially the same at different tow depths. The L-
DEO model does not allow for bottom interactions, and thus is most 
directly applicable to deep water.
    Table 1 summarizes the predicted distances at which sound levels 
(160- and 180-dB) are expected to be received from the 36-airgun array 
and a single airgun operating in deep water. 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. 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. 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.

 Table 1--Measured (Array) or Predicted (Single Airgun) Distances To Which Sound Levels Greater Than or Equal to
160 and 180 dB re: 1 [mu]PaRms That Could Be Received in Deep Water Using a 36-Airgun Array, as Well as a Single
Airgun Towed at a Depth of 9 m (29.5 ft) During the Proposed Survey in the Northwest Pacific Ocean, During March-
                                                   April, 2012
                            [Distances Are Based On Model Results Provided By L-DEO]
----------------------------------------------------------------------------------------------------------------
                                                                         Predicted RMS Distances (m)
         Source and volume                Water depth      -----------------------------------------------------
                                                                 160 dB            180 dB            190 dB
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun (40 in\3\)......  Deep (>1,000 m)......               385                40                12
36-Airgun Array....................  .....................             3,850               940               400
----------------------------------------------------------------------------------------------------------------

    Appendix A of NSF's EA discusses L-DEO's calculations for the 
model. NMFS refers the reviewers to L-DEO's application and the NSF's 
EA for additional information.

Multibeam Echosounder

    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 kilohertz (kHz)) in a fan-shaped beam that extends downward 
and to the sides of the ship. The transmitting beamwidth is one or two 
degrees ([deg]) fore-aft and 150 [deg] athwartship and the maximum 
source level is 242 dB re: 1 [mu]Pa.
    For deep-water operations, each ping consists of eight (in water 
greater than 1,000 m; 3,280 ft) or four (less than 1,000 m; 3,280 ft) 
successive, fan-shaped transmissions, from two to 15 milliseconds (ms) 
in duration and each ensonifying a sector that extends 1 [deg] fore-
aft. Continuous wave pulses increase from two to 15 milliseconds (ms) 
long in water depths up to 2,600 m (8,530 ft). The MBES uses frequency-
modulated chirp pulses up to 100-ms long in water greater than 2,600 m 
(8,530 ft). The eight successive transmissions span an overall cross-
track angular extent of about 150 [deg], with

[[Page 4769]]

2-ms gaps between the pulses for successive sectors.

Sub-bottom Profiler

    The Langseth will also operate a Knudsen Chirp 3260 SBP 
concurrently during airgun and MBES operations to provide information 
about the sedimentary features and bottom topography. The SBP is 
capable of reaching depths of 10,000 m (6.2 mi). The dominant frequency 
component of the SBP is 3.5 kHz which is directed downward in a 27[deg] 
cone by a hull-mounted transducer on the vessel. The nominal power 
output is 10 kilowatts (kW), but the actual maximum radiated power is 
three kW or 222 dB re: 1 [mu]Pa. The ping duration is up to 64 ms with 
a pulse interval of one second, but a common mode of operation is to 
broadcast five pulses at 1-s intervals followed by a 5-s 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 in a temporary modification in behavior and/or low-level 
physiological effects (Level B harassment only) 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 kts; 8.5 km/hr; 5.3 mph) during 
seismic acquisition.

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

    Thirty-four marine mammal species may occur in the Shatsky Rise 
survey area, including 26 odontocetes (toothed cetaceans), seven 
mysticetes (baleen whales) and one species of pinniped during March 
through April. Six of these species are listed as endangered under the 
Endangered Species Act of 1973 (ESA; 16 U.S.C. 1531 et seq.), including 
the blue (Balaenoptera musculus), fin (Balaenoptera physalus), humpback 
(Megaptera novaeangliae), north Pacific right (Eubalaena japonica), sei 
(Balaenoptera borealis), and sperm (Physeter macrocephalus) whales.
    Based on available data, the western north Pacific gray whale 
(Eschrichtius robustus) may have the potential to migrate off of the 
Pacific coast of Japan (Reilly et al., 2008a), though any occurrence in 
the survey area would be rare as gray whales are known to prefer 
nearshore coastal waters. Based on available data, L-DEO does not 
expect to encounter the western north Pacific gray whale within the 
proposed study area and does not present analysis for these species. 
Accordingly, NMFS did not consider this cetacean species in greater 
detail and the proposed IHA will only address requested take 
authorizations for the seven mysticetes, 26 odontocetes, and one 
species of pinniped. The species of marine mammals expected to be most 
common in the survey area (all delphinids) include the short-beaked 
common (Delphinus delphis), striped (Stenella coeruleoalba), and 
Fraser's (Lagenodelphis hosei) dolphins, and Dall's porpoise 
(Phocoenoides dalli).
    Table 2 presents information on the abundance, distribution, and 
conservation status of the marine mammals that may occur in the 
proposed survey area March through April, 2012.

  Table 2--Habitat, Abundance, and Conservation Status of Marine Mammals That May Occur in or Near the Proposed
                     Seismic Survey Area on the Shatsky Rise in the Northwest Pacific Ocean
            [See text and Tables 2 and 3 in L-DEO's application and the NSF's EA for further details]
----------------------------------------------------------------------------------------------------------------
            Species                  Habitat        Abundance in the NW Pacific      ESA \1\        Density \2\
----------------------------------------------------------------------------------------------------------------
Mysticetes
    North Pacific right whale.  Pelagic, coastal.  few 100 \3\.................  EN.............            0.04
    Humpback whale............  Mainly nearshore,  938-1107 \4\................  EN.............            0.47
                                 banks.
    Minke whale...............  Pelagic, coastal.  25,000 \5\..................  NL.............            2.51
    Bryde's whale.............  Pelagic, coastal.  20,501 \6\..................  NL.............            0.52
    Sei whale.................  Primarily          7260-12,620 \7\.............  EN.............            1.78
                                 offshore,
                                 pelagic.
    Fin whale.................  Continental        13,620-18,680 \8\...........  EN.............            0.74
                                 slope, mostly
                                 pelagic.
    Blue whale................  Pelagic, coastal.  3500 \9\....................  EN.............            0.39
Odontocetes
    Sperm whale...............  Usually pelagic,   29,674 \10\.................  EN.............            1.04
                                 deep sea.
    Pygmy sperm whale.........  Deep waters off    N.A.........................  NL.............            3.19
                                 the shelf.
    Dwarf sperm whale.........  Deep waters off    11,200 \11\.................  NL.............            7.82
                                 the shelf.
    Cuvier's beaked whale.....  Pelagic..........  20,000 \11\.................  NL.............            6.80
    Baird's beaked whale......  Deep water.......  N.A.........................  NL.............            0.88
    Longman's beaked whale....  Deep water.......  N.A.........................  NL.............            0.45
    Hubb's beaked whale.......  Deep water.......  25,300 \12\.................  NL.............            1.28
    Ginkgo-toothed beaked       Pelagic..........  25,300 \12\.................  NL.............            0.01
     whale.
    Blainville's beaked whale.  Pelagic..........  25,300 \12\.................  NL.............            3.12
    Stejneger's beaked whale..  Deep water.......  25,300 \12\.................  NL.............           23.99
    Rough-toothed dolphin.....  Deep water.......  145,900 \11\................  NL.............           70.41
    Common bottlenose dolphin.  Coastal, oceanic,  168,000 \13\................  NL.............            0.83
                                 shelf break.
    Pantropical spotted         Pelagic, coastal.  438,000 \13\................  NL.............          119.07
     dolphin.
    Spinner dolphin...........  Pelagic, coastal.  801,000 \14\................  NL.............            4.57
    Striped dolphin...........  Off continental    570,000 \13\................  NL.............          309.35
                                 shelf.
    Fraser's dolphin..........  Waters >1000 m...  289,300 \11\................  NL.............           36.40
    Short-beaked common         Shelf, pelagic,    2,963,000 \15\..............  NL.............            0.41
     dolphin.                    seamounts.
    Pacific white-sided         Continental        988,000 \16\................  NL.............           10.8
     dolphin.                    slope, pelagic.
    Northern right whale        Deep water.......  307,000 \16\................  NL.............            1.32
     dolphin.
    Risso's dolphin...........  Deep water,        838,000 \13\................  NL.............            0
                                 seamounts.
    Melon-headed whale........  Oceanic..........  45,400 \11\.................  NL.............            2.05
    Pygmy killer whale........  Deep, pantropical  38,900 \11\.................  NL.............            0.16
                                 waters.
    False killer whale........  Pelagic..........  16,000 \13\.................  NL.............            5.00
    Killer whale..............  Widely             8500 \11\...................  NL.............           21.94
                                 distributed.

[[Page 4770]]

 
    Short-finned pilot whale..  Mostly pelagic,    53,000 \13\.................  NL.............            1.04
                                 high-relief.
    Dall's porpoise...........  Deep water.......  1,337,224 \17\..............  NL.............            3.19
Pinnipeds
    Northern fur seal.........  Pelagic, coastal.  1.1 million \18\............  NL.............            1.79 
----------------------------------------------------------------------------------------------------------------
N.A.--Not available or not assessed.
\1\ Endangered Species Act: EN = Endangered, NL = Not listed
\2\ Density estimate as listed in Table 3 of L-DEO's application. Refer to page 41 for specific references.
\3\ North Pacific (Jefferson et al. 2008).
\4\ Western North Pacific (Calambokidis et al. 2008).
\5\ Northwest Pacific and Okhotsk Sea (Buckland et al. 1992; IWC 2010a).
\6\ Western North Pacific (Kitakado et al. 2008; IWC 2010a).
\7\ North Pacific (Tillman 1977).
\8\ North Pacific (Ohsumi and Wada 1974).
\9\ North Pacific (NMFS 1998).
\10\ Western North Pacific (Whitehead 2002b).
\11\ Eastern Tropical Pacific (ETP) (Wade and Gerrodette 1993).
\12\ ETP; all Mesoplodon spp. (Wade and Gerrodette 1993).
\13\ Western North Pacific (Miyashita 1993a).
\14\ Whitebelly spinner dolphin in the ETP in 2000 (Gerrodette et al. 2005 in Hammond et al 2008a).
\15\ ETP (Gerrodette and Forcada 2002 in Hammond et al 2008b).
\16\ North Pacific (Miyashita 1993b).
\17\ North Pacific (Buckland et al 1993).
\18\ North Pacific, 2004-2005 (Gelatt and Lowry 2008).

    NMFS refers the reader to Sections 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 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

    Studies on marine mammals' tolerance to sound in the natural 
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 manmade 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. 
Several studies have shown that marine mammals at distances more than a 
few kilometers from operating seismic vessels often show no apparent 
response (see Appendix B(5) in NSF's EA). That is often true even in 
cases when the pulsed sounds must be readily audible to the animals 
based on measured received levels and the hearing sensitivity of the 
marine mammal group. Although various baleen whales and toothed whales, 
and (less frequently) pinnipeds have been shown to react behaviorally 
to airgun pulses under some conditions, at other times marine mammals 
of all three types have shown no overt reactions (Stone 2003; Stone and 
Tasker 2006; Moulton et al. 2005, 2006a; Weir 2008a for sperm whales), 
(MacLean and Koski 2005; Bain and Williams 2006 for Dall's porpoises). 
The relative responsiveness of baleen and toothed whales are quite 
variable.

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).
    NMFS expects the masking effects of pulsed sounds (even from large 
arrays of airguns) on marine mammal calls and other natural sounds to 
be limited, although there are very few specific data on this. Because 
of the intermittent nature and low duty cycle of seismic

[[Page 4771]]

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 NSF'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 (Enhydra lutris), but for many species there are 
no data on responses to marine seismic surveys.
    Baleen Whales--Baleen whales generally tend to avoid operating 
airguns, but avoidance radii are quite variable (reviewed in Richardson 
et al., 1995). Whales are often reported to show no overt reactions to 
pulses from large arrays of airguns at distances beyond a few 
kilometers, even though the airgun pulses remain well above ambient 
noise levels out to much longer distances. However, as reviewed in 
Appendix B(5) of the NSF's EA, baleen whales exposed to strong noise 
pulses from airguns often react by deviating from their normal 
migration route and/or interrupting their feeding and moving away from 
the area. 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 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 NSF's 
EA have shown that some species of baleen whales, notably bowhead and 
humpback whales, at times show strong avoidance at received levels 
lower than 160-170 dB re: 1 [mu]Pa.
    Researchers have studied the responses of humpback whales to 
seismic surveys during migration, feeding during the summer months, 
breeding while offshore from Angola, and wintering offshore from 
Brazil. McCauley et al. (1998, 2000a) studied the responses of humpback 
whales off western Australia to a full-scale seismic survey with a 16-
airgun array (2,678-in\3\) and to a single, 20-in\3\ airgun with source 
level of 227 dB re: 1 [micro]Pa (p-p). In the 1998 study, the 
researchers documented that avoidance reactions began at five to eight 
km (3.1 to 4.9 mi) from the array, and that those reactions kept most 
pods approximately three to four km (1.9 to 2.5 mi) from the operating 
seismic boat. In the 2000 study, McCauley et al. noted localized 
displacement during migration of four to five km (2.5 to 3.1 mi) by 
traveling pods and seven to 12 km (4.3 to 7.5 mi) by more sensitive 
resting pods of cow-calf pairs. Avoidance distances with respect to the 
single airgun were smaller but consistent with the results from the 
full array in terms of the received sound levels. The mean received 
level for initial avoidance of an approaching airgun was 140 dB re: 1 
[mu]Pa for humpback pods containing females, and at the mean closest 
point of approach distance, the received level was 143 dB re: 1 [mu]Pa. 
The initial avoidance response generally occurred at distances of five 
to eight km (3.1 to 4.9 mi) from the airgun array and two km (1.2 mi) 
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.
    Data collected by observers during several seismic surveys in the 
northwest Atlantic Ocean 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 versus non-seismic periods 
(Moulton and Holst, 2010).
    Humpback whales on their summer feeding grounds in Frederick Sound 
and Stephens Passage, Alaska did not

[[Page 4772]]

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 
re: 1 [mu]Pa.
    Other 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). Although, 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 (12.4 to 18.6 mi) from a medium-sized airgun source at 
received sound levels of approximately 120 to 130 dB re: 1 [mu]Pa 
(Miller et al., 1999; Richardson et al., 1999; see Appendix B(5) of 
NSF's EA). However, more recent research on bowhead whales (Miller et 
al., 2005; Harris et al., 2007) corroborates earlier evidence that, 
during the summer feeding season, bowheads are not as sensitive to 
seismic sources. Nonetheless, subtle but statistically significant 
changes in surfacing--respiration--dive cycles were evident upon 
statistical analysis (Richardson et al., 1986). In the summer, bowheads 
typically begin to show avoidance reactions at received levels of about 
152 to 178 dB re: 1 [mu]Pa (Richardson et al., 1986, 1995; Ljungblad et 
al., 1988; Miller et al., 2005).
    Reactions of migrating and feeding (but not wintering) gray whales 
to seismic surveys have been studied. Malme et al. (1986, 1988) studied 
the responses of feeding eastern Pacific gray whales to pulses from a 
single 100-in\3\ airgun off St. Lawrence Island in the northern Bering 
Sea. They estimated, based on small sample sizes, that 50 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. 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) 
also observed localized avoidance by fin whales during seismic airgun 
events in the western Mediterranean Sea and adjacent Atlantic waters 
from 2006-2009. They reported that singing fin whales moved away from 
an operating airgun array for a time period that extended beyond the 
duration of the airgun activity.
    Ship-based monitoring studies of baleen whales (including blue, 
fin, sei, minke, and whales) in the northwest Atlantic found that 
overall, this group had lower sighting rates during seismic versus non-
seismic periods (Moulton and Holst, 2010). Baleen whales as a group 
were also seen significantly farther from the vessel during seismic 
compared with non-seismic periods, and they were more often seen to be 
swimming away from the operating seismic vessel (Moulton and Holst, 
2010). Blue and minke whales were initially sighted significantly 
farther from the vessel during seismic operations compared to non-
seismic periods; the same trend was observed for fin whales (Moulton 
and Holst, 2010). Minke whales were most often observed to be swimming 
away from the vessel when seismic operations were underway (Moulton and 
Holst, 2010).
    Data on short-term reactions by cetaceans to impulsive noises are 
not necessarily indicative of long-term or biologically significant 
effects. It is not known whether impulsive sounds affect reproductive 
rate or distribution and habitat use in subsequent days or years. 
However, gray whales have continued to migrate annually along the west 
coast of North America with substantial increases in the population 
over recent years, despite intermittent seismic exploration (and much 
ship traffic) in that area for decades (Appendix A in Malme et al., 
1984; Richardson et al., 1995; Allen and Angliss, 2011). 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 Agliss, 2011).
    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 earlier and 
(in more detail) in Appendix B of NSF's EA have been reported for 
toothed whales. However, there are recent systematic studies on sperm 
whales (e.g., Gordon et al., 2006; Madsen et al., 2006; Winsor and 
Mate, 2006; Jochens et al., 2008; Miller et al., 2009). There is an 
increasing amount of information about responses of various odontocetes 
to seismic surveys based on monitoring studies (e.g., Stone, 2003; 
Smultea et al., 2004; Moulton and Miller, 2005; Bain and Williams, 
2006; Holst et al., 2006; Stone and Tasker, 2006; Potter et al., 2007; 
Hauser et al., 2008; Holst and Smultea, 2008; Weir, 2008; Barkaszi et 
al., 2009; Richardson et al., 2009; Moulton and Holst, 2010).
    Seismic operators and protected species observers (PSOs) on seismic 
vessels regularly see dolphins and other small toothed whales near 
operating airgun arrays, but in general there is a tendency for most 
delphinids to show some avoidance of operating seismic vessels (e.g., 
Goold, 1996a,b,c; Calambokidis and Osmek, 1998; Stone, 2003; Moulton 
and Miller, 2005; Holst et al., 2006; Stone and Tasker, 2006; Weir, 
2008; Richardson et al., 2009; Barkaszi et al., 2009; Moulton and

[[Page 4773]]

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. 
Summer aerial surveys conducted in the southeastern Beaufort Sea 
reported that sighting rates of beluga whales were significantly lower 
at distances of 10 to 20 km (6.2 to 12.4 mi) from an operating airgun 
array compared to distances of 20 to 30 km (12.4 to 18.6 mi). Further, 
PSOs on seismic boats in that area have rarely reported sighting beluga 
whales (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 (Phocoena phocoena) show stronger 
avoidance of seismic operations than do Dall's porpoises (Stone, 2003; 
MacLean and Koski, 2005; Bain and Williams, 2006; Stone and Tasker, 
2006). Dall's porpoises seem relatively tolerant of airgun operations 
(MacLean and Koski, 2005; Bain and Williams, 2006), although they too 
have been observed to avoid large arrays of operating airguns 
(Calambokidis and Osmek, 1998; Bain and Williams, 2006). This apparent 
difference in responsiveness of these two porpoise species is 
consistent with their relative responsiveness to boat traffic and some 
other acoustic sources (Richardson et al., 1995; Southall et al., 
2007).
    Most studies of sperm whales exposed to airgun sounds indicate that 
the sperm whale shows considerable tolerance of airgun pulses (e.g., 
Stone, 2003; Moulton et al., 2005, 2006a; Stone and Tasker, 2006; Weir, 
2008). In most cases the whales do not show strong avoidance, and they 
continue to call (see Appendix B of NSF's EA for 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 (Ziphius cavirostris) 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 (See Appendix B of NSF'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 NSF's 
EA. In the Beaufort Sea, some ringed seals avoided an area of 100 m 
(328 ft) to (at most) a few hundred meters around seismic vessels, but 
many seals remained within 100 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 et 
al., 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-

[[Page 4774]]

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 (introduced 
earlier in this document) 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 [mu]Pa.
    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. 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. 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 SPLs exceeding 160 dB re: 1 [mu]Pa 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 low abundance 
of baleen whales in the planned study area at the time of the survey, 
and 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 (nonpulse) 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 
indirectly estimated TTS threshold for pulsed sounds would be 
approximately 181 to 186 dB re: 1 [mu]Pa (Southall et al., 2007), or a 
series of pulses for which the highest SEL 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 times-see Appendix B(6) 
of NSF's EA. Based on data from terrestrial mammals, a precautionary 
assumption is that the PTS threshold for impulse sounds (such as airgun 
pulses as received close to the source) is at least 6 dB higher than 
the TTS threshold on a peak-pressure basis, and probably greater than 
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

    When a live or dead marine mammal swims or floats onto shore and 
becomes ``beached'' or incapable of returning to sea, the event is 
termed a ``stranding'' (Geraci et al., 1999; Perrin and Geraci, 2002; 
Geraci and Lounsbury, 2005; NMFS, 2007). The legal definition for a 
stranding under the MMPA is that ``(A) a marine mammal is dead and is 
(i) on a beach or shore of the United States; or (ii) in waters under 
the jurisdiction of the United States (including any navigable waters); 
or (B) a marine mammal is alive and is (i) on a beach or shore of the 
United States and is unable to return to the water; (ii) on a beach or 
shore of the United States and, although able to return to the water, 
is in need of apparent medical attention; or (iii) in the waters under 
the jurisdiction of the United States (including any navigable waters), 
but is unable to return to its natural habitat under its own power or 
without assistance'' (16 U.S.C. 1421h).
    Marine mammals are known to strand for a variety of reasons, such 
as infectious agents, biotoxicosis, starvation, fishery interaction, 
ship strike, unusual oceanographic or weather events, sound exposure, 
or combinations of these stressors sustained concurrently or in series. 
However, the cause or causes of most strandings are unknown (Geraci et 
al., 1976; Eaton, 1979; Odell et al., 1980; Best, 1982). Numerous 
studies suggest that the physiology, behavior, habitat relationships, 
age, or condition of cetaceans may cause them to strand or might 
predispose them to strand when exposed to another phenomenon. These 
suggestions are consistent with the conclusions of numerous other 
studies that have demonstrated that

[[Page 4775]]

combinations of dissimilar stressors commonly combine to kill an animal 
or dramatically reduce its fitness, even though one exposure without 
the other does not produce the same result (Chroussos, 2000; Creel, 
2005; DeVries et al., 2003; Fair and Becker, 2000; Foley et al., 2001; 
Moberg, 2000; Relyea, 2005a; 2005b, Romero, 2004; Sih et al., 2004).
    Strandings Associated with Military Active Sonar--Several sources 
have published lists of mass stranding events of cetaceans in an 
attempt to identify relationships between those stranding events and 
military active sonar (Hildebrand, 2004; IWC, 2005; Taylor et al., 
2004). For example, based on a review of stranding records between 1960 
and 1995, the International Whaling Commission (2005) identified ten 
mass stranding events and concluded that, out of eight stranding events 
reported from the mid-1980s to the summer of 2003, seven had been 
coincident with the use of mid-frequency active sonar and most involved 
beaked whales.
    Over the past 12 years, there have been five stranding events 
coincident with military MF active sonar use in which exposure to sonar 
is believed by NMFS and the Navy to have been a contributing factor to 
strandings: Greece (1996); the Bahamas (2000); Madeira (2000); Canary 
Islands (2002); and Spain (2006). NMFS refers the reader to Cox et al. 
(2006) for a summary of common features shared by the strandings events 
in Greece (1996), Bahamas (2000), Madeira (2000), and Canary Islands 
(2002); and Fernandez et al., (2005) for an additional summary of the 
Canary Islands 2002 stranding event.
    Potential for Stranding from Seismic Surveys--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 NSF's EA provides additional details.
    Specific sound-related processes that lead to strandings and 
mortality are not well documented, but may include:
    (1) Swimming in avoidance of a sound into shallow water;
    (2) A change in behavior (such as a change in diving behavior) that 
might contribute to tissue damage, gas bubble formation, hypoxia, 
cardiac arrhythmia, hypertensive hemorrhage or other forms of trauma;
    (3) A physiological change such as a vestibular response leading to 
a behavioral change or stress-induced hemorrhagic diathesis, leading in 
turn to tissue damage; and
    (4) Tissue damage directly from sound exposure, such as through 
acoustically-mediated bubble formation and growth or acoustic resonance 
of tissues. Some of these mechanisms are unlikely to apply in the case 
of impulse sounds. However, there are increasing 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 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 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

[[Page 4776]]

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. The beam is narrow (1 to 2[deg]) in fore-aft extent and wide 
(150[deg]) in the cross-track extent. Each ping consists of eight (in 
water greater than 1,000 m deep) or four (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 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 vessel (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 in this section.
    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 [mu]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 Ocean, 
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.
    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.
    Based upon the best available science, 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 an 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 sub-bottom profiler on the Langseth has a maximum source 
level of 222 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 and 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. Many marine mammals will move 
away in response to the approaching higher-power sources or the vessel 
itself before the

[[Page 4777]]

mammals would be close enough for there to be any possibility of 
effects from the less intense sounds from the SBP. Based upon the best 
available science, NMFS believes that the brief exposure of marine 
mammals to signals from the SBP is not likely to result in the 
harassment of marine mammals.

Potential Effects of Vessel Movement and Collisions

    Vessel movement in the vicinity of marine mammals has the potential 
to result in either a behavioral response or a direct physical 
interaction. Both scenarios are discussed below this section.

Behavioral Responses to Vessel Movement

    There are limited data concerning marine mammal behavioral 
responses to vessel traffic and vessel noise, and a lack of consensus 
among scientists with respect to what these responses mean or whether 
they result in short-term or long-term adverse effects. In those cases 
where there is a busy shipping lane or where there is a large amount of 
vessel traffic, marine mammals may experience acoustic masking 
(Hildebrand, 2005) if they are present in the area (e.g., killer whales 
in Puget Sound; Foote et al., 2004; Holt et al., 2008). In cases where 
vessels actively approach marine mammals (e.g., whale watching or 
dolphin watching boats), scientists have documented that animals 
exhibit altered behavior such as increased swimming speed, erratic 
movement, and active avoidance behavior (Bursk, 1983; Acevedo, 1991; 
Baker and MacGibbon, 1991; Trites and Bain, 2000; Williams et al., 
2002; Constantine et al., 2003), reduced blow interval (Ritcher et al., 
2003), disruption of normal social behaviors (Lusseau, 2003; 2006), and 
the shift of behavioral activities which may increase energetic costs 
(Constantine et al., 2003; 2004). A detailed review of marine mammal 
reactions to ships and boats is available in Richardson et al. (1995). 
For each of the marine mammal taxonomy groups, Richardson et al. (1995) 
provides the following assessment regarding reactions to vessel 
traffic:
    Toothed whales: ``In summary, toothed whales sometimes show no 
avoidance reaction to vessels, or even approach them. However, 
avoidance can occur, especially in response to vessels of types used to 
chase or hunt the animals. This may cause temporary displacement, but 
we know of no clear evidence that toothed whales have abandoned 
significant parts of their range because of vessel traffic.''
    Baleen whales: ``When baleen whales receive low-level sounds from 
distant or stationary vessels, the sounds often seem to be ignored. 
Some whales approach the sources of these sounds. When vessels approach 
whales slowly and non-aggressively, whales often exhibit slow and 
inconspicuous avoidance maneuvers. In response to strong or rapidly 
changing vessel noise, baleen whales often interrupt their normal 
behavior and swim rapidly away. Avoidance is especially strong when a 
boat heads directly toward the whale.''
    Behavioral responses to stimuli are complex and influenced to 
varying degrees by a number of factors, such as species, behavioral 
contexts, geographical regions, source characteristics (moving or 
stationary, speed, direction, etc.), prior experience of the animal and 
physical status of the animal. For example, studies have shown that 
beluga whales' reactions varied when exposed to vessel noise and 
traffic. In some cases, naive beluga whales exhibited rapid swimming 
from ice-breaking vessels up to 80 km (49.7 mi) away, and showed 
changes in surfacing, breathing, diving, and group composition in the 
Canadian high Arctic where vessel traffic is rare (Finley et al., 
1990). In other cases, beluga whales were more tolerant of vessels, but 
responded differentially to certain vessels and operating 
characteristics by reducing their calling rates (especially older 
animals) in the St. Lawrence River where vessel traffic is common 
(Blane and Jaakson, 1994). In Bristol Bay, Alaska, beluga whales 
continued to feed when surrounded by fishing vessels and resisted 
dispersal even when purposefully harassed (Fish and Vania, 1971).
    In reviewing more than 25 years of whale observation data, Watkins 
(1986) concluded that whale reactions to vessel traffic were ``modified 
by their previous experience and current activity: habituation often 
occurred rapidly, attention to other stimuli or preoccupation with 
other activities sometimes overcame their interest or wariness of 
stimuli.'' Watkins noticed that over the years of exposure to ships in 
the Cape Cod area, minke whales changed from frequent positive interest 
(e.g., approaching vessels) to generally uninterested reactions; fin 
whales changed from mostly negative (e.g., avoidance) to uninterested 
reactions; right whales apparently continued the same variety of 
responses (negative, uninterested, and positive responses) with little 
change; and humpbacks dramatically changed from mixed responses that 
were often negative to reactions that were often strongly positive. 
Watkins (1986) summarized that ``whales near shore, even in regions 
with low vessel traffic, generally have become less wary of boats and 
their noises, and they have appeared to be less easily disturbed than 
previously. In particular locations with intense shipping and repeated 
approaches by boats (such as the whale-watching areas of Stellwagen 
Bank), more and more whales had positive reactions to familiar vessels, 
and they also occasionally approached other boats and yachts in the 
same ways.''
    Although the radiated sound from the Langseth will be audible to 
marine mammals over a large distance, it is unlikely that animals will 
respond behaviorally (in a manner that NMFS would consider MMPA 
harassment) to low-level distant shipping noise as the animals in the 
area are likely to be habituated to such noises (Nowacek et al., 2004). 
In light of these facts, NMFS does not expect the Langseth's movements 
to result in Level B harassment.

Vessel Strike

    Ship strikes of cetaceans can cause major wounds, which may lead to 
the death of the animal. An animal at the surface could be struck 
directly by a vessel, a surfacing animal could hit the bottom of a 
vessel, or an animal just below the surface could be cut by a vessel's 
propeller. The severity of injuries typically depends on the size and 
speed of the vessel (Knowlton and Kraus, 2001; Laist et al., 2001; 
Vanderlaan and Taggart, 2007).
    The most vulnerable marine mammals are those that spend extended 
periods of time at the surface in order to restore oxygen levels within 
their tissues after deep dives (e.g., the sperm whale). In addition, 
some baleen whales, such as the North Atlantic right whale, seem 
generally unresponsive to vessel sound, making them more susceptible to 
vessel collisions (Nowacek et al., 2004). These species are primarily 
large, slow moving whales. Smaller marine mammals (e.g., bottlenose 
dolphin) move quickly through the water column and are often seen 
riding the bow wave of large ships. Marine mammal responses to vessels 
may include avoidance and changes in dive pattern (NRC, 2003).
    An examination of all known ship strikes from all shipping sources 
(civilian and military) indicates vessel speed is a principal factor in 
whether a vessel strike results in death (Knowlton and Kraus, 2001; 
Laist et al., 2001; Jensen and Silber, 2003; Vanderlaan and Taggart, 
2007). In assessing records in which vessel speed was known, Laist et

[[Page 4778]]

al. (2001) found a direct relationship between the occurrence of a 
whale strike and the speed of the vessel involved in the collision. The 
authors concluded that most deaths occurred when a vessel was traveling 
in excess of 14.9 mph (24.1 km/hr; 13 kts).
    L-DEO's proposed operation of one vessel for the proposed survey is 
relatively small in scale compared to the number of commercial ships 
transiting at higher speeds in the same areas on an annual basis. The 
probability of vessel and marine mammal interactions occurring during 
proposed survey is unlikely due to the Langseth's slow operational 
speed, which is typically 4.6 kts (8.5 km/h; 5.3 mph). Outside of 
operations, the Langseth's cruising speed would be approximately 11.5 
mph (18.5 km/h; 10 kts) which is generally below the speed at which 
studies have noted reported increases of marine mammal injury or death 
(Laist et al., 2001).
    As a final point, the Langseth has a number of other advantages for 
avoiding ship strikes as compared to most commercial merchant vessels, 
including the following: the Langseth's bridge offers good visibility 
to visually monitor for marine mammal presence; PSVOs posted during 
operations scan the ocean for marine mammals and must report visual 
alerts of marine mammal presence to crew; and the PSVOs receive 
extensive training that covers the fundamentals of visual observing for 
marine mammals and information about marine mammals and their 
identification at sea.
    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 is not anticipated to have any 
permanent impact on habitats used by the marine mammals in the proposed 
survey area, including the food sources they use (i.e., fish and 
invertebrates). Additionally, no physical damage to any habitat is 
anticipated as a result of conducting the proposed seismic survey. 
While it is anticipated that the specified activity may result in 
marine mammals avoiding certain areas due to temporary ensonification, 
this impact to habitat is temporary and reversible and was considered 
in further detail earlier in this document, as behavioral modification.
    The main impact associated with the proposed activity will be 
temporarily elevated noise levels and the associated direct effects on 
marine mammals, previously discussed in this notice. The next section 
discusses the potential impacts of anthropogenic sound sources on 
common marine mammal prey in the proposed survey area (i.e., fish and 
invertebrates).

Anticipated Effects on Fish

    One reason for the adoption of airguns as the standard energy 
source for marine seismic surveys is that, unlike explosives, they have 
not been associated with large-scale fish kills. However, existing 
information on the impacts of seismic surveys on marine fish 
populations is limited (see Appendix D of NSF's EA). There are three 
types of potential effects of exposure to seismic surveys: (1) 
Pathological, (2) physiological, and (3) behavioral. Pathological 
effects involve lethal and temporary or permanent sub-lethal injury. 
Physiological effects involve temporary and permanent primary and 
secondary stress responses, such as changes in levels of enzymes and 
proteins. Behavioral effects refer to temporary and (if they occur) 
permanent changes in exhibited behavior (e.g., startle and avoidance 
behavior). The three categories are interrelated in complex ways. For 
example, it is possible that certain physiological and behavioral 
changes could potentially lead to an ultimate pathological effect on 
individuals (i.e., mortality).
    The specific received sound levels at which permanent adverse 
effects to fish potentially could occur are little studied and largely 
unknown. Furthermore, the available information on the impacts of 
seismic surveys on marine fish is from studies of individuals or 
portions of a population; there have been no studies at the population 
scale. The studies of individual fish have often been on caged fish 
that were exposed to airgun pulses in situations not representative of 
an actual seismic survey. Thus, available information provides limited 
insight on possible real-world effects at the ocean or population 
scale.
    Hastings and Popper (2005), Popper (2009), and Popper and Hastings 
(2009a,b) provided recent critical reviews of the known effects of 
sound on fish. The following sections provide a general synopsis of the 
available information on the effects of exposure to seismic and other 
anthropogenic sound as relevant to fish. The information comprises 
results from scientific studies of varying degrees of rigor plus some 
anecdotal information. Some of the data sources may have serious 
shortcomings in methods, analysis, interpretation, and reproducibility 
that must be considered when interpreting their results (see Hastings 
and Popper, 2005). Potential adverse effects of the program's sound 
sources on marine fish are then 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 of NSF's EA). For a given sound to result in 
hearing loss, the sound must exceed, by some substantial amount, the 
hearing threshold of the fish for that sound (Popper, 2005). The 
consequences of temporary or permanent hearing loss in individual fish 
on a fish population are unknown; however, they likely depend on the 
number of individuals affected and whether critical behaviors involving 
sound (e.g., predator avoidance, prey capture, orientation and 
navigation, reproduction, etc.) are adversely affected.
    Little is known about the mechanisms and characteristics of damage 
to fish that may be inflicted by exposure to seismic survey sounds. Few 
data have been presented in the peer-reviewed scientific literature. As 
far as we 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

[[Page 4779]]

fish because the water in the study areas was very shallow 
(approximately 9 m in the former case and less than two m in the 
latter). Water depth sets a lower limit on the lowest sound frequency 
that will propagate (the ``cutoff frequency'') at about one-quarter 
wavelength (Urick, 1983; Rogers and Cox, 1988).
    Wardle et al. (2001) suggested that in water, acute injury and 
death of organisms exposed to seismic energy depends primarily on two 
features of the sound source: (1) The received peak pressure, and (2) 
the time required for the pressure to rise and decay. Generally, as 
received pressure increases, the period for the pressure to rise and 
decay decreases, and the chance of acute pathological effects 
increases. According to Buchanan et al. (2004), for the types of 
seismic airguns and arrays involved with the proposed program, the 
pathological (mortality) zone for fish would be expected to be within a 
few meters of the seismic source. Numerous other studies provide 
examples of no fish mortality upon exposure to seismic sources (Falk 
and Lawrence, 1973; Holliday et al., 1987; La Bella et al., 1996; 
Santulli et al., 1999; McCauley et al., 2000a,b, 2003; Bjarti, 2002; 
Thomsen, 2002; Hassel et al., 2003; Popper et al., 2005; Boeger et al., 
2006).
    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 NSF's EA).
    Behavioral Effects--Behavioral effects include changes in the 
distribution, migration, mating, and catchability of fish populations. 
Studies investigating the possible effects of sound (including seismic 
survey sound) on fish behavior have been conducted on both uncaged and 
caged individuals (e.g., Chapman and Hawkins, 1969; Pearson et al., 
1992; Santulli et al., 1999; Wardle et al., 2001; Hassel et al., 2003). 
Typically, in these studies fish exhibited a sharp startle response at 
the onset of a sound 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 streamer may become entangled 
with various types of fishing gear. 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 fisheries in the western 
Pacific Ocean. 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 
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 NSF's EA).
    The only information available on the impacts of seismic surveys on 
marine invertebrates involves studies of individuals; there have been 
no studies at the population scale. Thus, available information 
provides limited insight on possible real-world effects at the regional 
or ocean scale. The most important aspect of potential impacts concerns 
how exposure to seismic survey sound ultimately affects invertebrate 
populations and their viability, including availability to fisheries.
    Literature reviews of the effects of seismic and other underwater 
sound on invertebrates were provided by Moriyasu et al. (2004) and 
Payne et al. (2008). The following sections provide a synopsis of 
available information on the effects of exposure to seismic survey 
sound on species of decapod crustaceans and cephalopods, the two 
taxonomic groups of invertebrates on which most such studies have been 
conducted. The available information is from studies with variable 
degrees of scientific soundness and from anecdotal information. A more 
detailed review of the literature on the effects of seismic survey 
sound on invertebrates is provided in Appendix 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

[[Page 4780]]

crustaceans and cephalopods is expected to be within a few meters of 
the seismic source, at most; however, very few specific data are 
available on levels of seismic signals that might damage these animals. 
This premise is based on the peak pressure and rise/decay time 
characteristics of seismic airgun arrays currently in use around the 
world.
    Some studies have suggested that seismic survey sound has a limited 
pathological impact on early developmental stages of crustaceans 
(Pearson et al., 1994; Christian et al., 2003; DFO, 2004). However, the 
impacts appear to be either temporary or insignificant compared to what 
occurs under natural conditions. Controlled field experiments on adult 
crustaceans (Christian et al., 2003, 2004; DFO, 2004) and adult 
cephalopods (McCauley et al., 2000a,b) exposed to seismic survey sound 
have not resulted in any significant pathological impacts on the 
animals. It has been suggested that exposure to commercial seismic 
survey activities has injured giant squid (Guerra et al., 2004), but 
the article provides little evidence to support this claim.
    Andre et al. (2011) exposed four cephalopod species (Loligo 
vulgaris, Sepia officinalis, Octopus vulgaris, and Ilex coindetii) to 
two hours of continuous sound from 50 to 400 Hz at 157  5 
dB re: 1 [mu]Pa. They reported lesions to the sensory hair cells of the 
statocysts of the exposed animals that increased in severity with time, 
suggesting that cephalopods are particularly sensitive to low-frequency 
sound.
    The received SPL was reported as 157  5 dB re: 1 
[mu]Pa, with peak levels at 175 dB re 1 [mu]Pa. As in the McCauley et 
al. (2003) paper on sensory hair cell damage in pink snapper as a 
result of exposure to seismic sound, the cephalopods were subjected to 
higher sound levels than they would be under natural conditions, and 
they were unable to swim away from the sound source.
    Physiological Effects--Physiological effects refer mainly to 
biochemical responses by marine invertebrates to acoustic stress. Such 
stress potentially could affect invertebrate populations by increasing 
mortality or reducing reproductive success. Primary and secondary 
stress responses (i.e., changes in haemolymph levels of enzymes, 
proteins, etc.) of crustaceans have been noted several days or months 
after exposure to seismic survey sounds (Payne et al., 2007). 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 would 
implement the following mitigation measures for marine mammals:
    (1) Proposed EZs;
    (2) Power-down procedures;
    (3) Shutdown procedures; and
    (4) Ramp-up procedures.
    Proposed Exclusion Zones--L-DEO uses safety radii to designate EZs 
and to estimate take for marine mammals. Table 1 (presented earlier in 
this document) shows the distances at which three sound levels (160-, 
180-, and 190-dB) are expected to be received from the 36-airgun array 
and a single airgun. The 180-dB and 190-dB level shut-down criteria are 
applicable to cetaceans and pinnipeds, respectively, as specified by 
NMFS (2000); and L-DEO used these levels to establish the EZs.
    If the protected species visual observer (PSVO) detects marine 
mammal(s) within or about to enter the appropriate EZ, the Langseth 
crew will immediately power down the airgun array, or perform a shut 
down if necessary (see Shut-down Procedures).
    Power-down Procedures--A power-down involves decreasing the number 
of airguns in use such that the radius of the 180-dB (or 190-dB) zone 
is decreased to the extent that marine mammals are no longer in or 
about to enter the EZ. A power down of the airgun array can also occur 
when the vessel is moving from one seismic line to another. During a 
power-down for mitigation, L-DEO will operate one airgun (40 in \3\). 
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 shutdown occurs when the Langseth suspends all airgun activity.
    If the PSVO detects a marine mammal outside the EZ, which is likely 
to enter the EZ, L-DEO will power-down the airguns before the animal 
enters 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 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 safety zone. 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

[[Page 4781]]

odontocetes or pinnipeds), or 30 min for species with longer dive 
durations (i.e., mysticetes and large odontocetes, including sperm, 
pygmy sperm, dwarf sperm, and beaked whales); or
     The vessel has moved outside the EZ (e.g., if a marine 
mammal is sighted close to the vessel and the ship speed is 8.5 km km/h 
(5.3 mph), it would take the vessel approximately eight minutes to 
leave the vicinity of the marine mammal).
    During airgun operations following a power-down or shutdown whose 
duration has exceeded the time limits specified previously, L-DEO will 
ramp up the airgun array gradually (see Shutdown 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.
    Considering the conservation status for north Pacific right whales, 
L-DEO will shut down the airgun(s) immediately in the unlikely event 
that this species is observed, regardless of the distance from the 
Langseth. L-DEO will only begin a ramp-up if the right whale has not 
been seen for 30 min.
    Ramp-up Procedures--L-DEO will follow a ramp-up procedure when the 
airgun subarrays begin operating after a specified period without 
airgun operations or when a power down has exceeded that period. L-DEO 
proposes that, for the present cruise, this period will be 
approximately eight minutes. This period is based on the 180-dB radius 
(940 m; 3,083 ft) for the 36-airgun array towed at a depth of 9 m (29.5 
ft) in relation to the minimum planned speed of the Langseth while 
shooting (8.5 km/h; 5.3 mph; 4.6 kts). L-DEO has used similar periods 
(8-10 min) during previous L-DEO surveys. L-DEO will not resume 
operations if a marine mammal has not cleared the EZ as described 
earlier.
    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-minute 
period over a total duration of approximately 30 min. During ramp-up, 
the PSVOs will monitor the EZ, and if he/she sights a marine mammal, L-
DEO will implement a power down or shut down as though the full airgun 
array were operational.
    If the complete EZ is not visible to the PSVO 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 L-DEO will not 
ramp up the airgun array from a complete shut-down at night or in thick 
fog, because the outer part of the EZ 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.
    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 prescribed the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. NMFS' 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' 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 mitigation measures provide 
the means of effecting the least practicable adverse impacts on marine 
mammals species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

Proposed Monitoring and Reporting

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

Proposed Monitoring

    L-DEO proposes to sponsor marine mammal monitoring during the 
present project, in order to implement the mitigation measures that 
require real-time monitoring, and to satisfy the 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

    L-DEO will position PSVOs aboard the seismic source vessel to watch 
for marine mammals near the vessel during daytime airgun operations and 
during any start-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 eight minutes for this proposed cruise). When feasible, 
the 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 Langseth will power down or 
shut down the airguns 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.

[[Page 4782]]

    During seismic operations on the Shatsky Rise, at least four 
protected species observers (PSO) (i.e., either a PSVO and/or a 
protected species acoustic observer (PSAO)) will be based aboard the 
Langseth. L-DEO will appoint the PSOs with NMFS' concurrence. The PSOs 
will conduct observations during ongoing daytime operations and 
nighttime ramp-ups of the airgun array. 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 mealtimes and bathroom breaks, it is 
sometimes difficult to have two PSVOs on effort, but at least one PSVO 
will be on watch during bathroom breaks and mealtimes. PSVOs will be on 
duty in shifts of no longer than four hours in duration.
    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). 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 observer 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., 7x50 Fujinon), Big-eye binoculars (25x150), 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 the PSVOs observe marine mammals within or about to enter the 
designated EZ, the Langseth will immediately power-down or shut-down 
the airguns 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, pygmy sperm, dwarf sperm, killer, and 
beaked whales).

Passive Acoustic Monitoring

    Passive Acoustic Monitoring (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 conjunction with 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. The PSAO will monitor the system in real time so that 
he/she can advise the PSVO when cetaceans are detected. When bearings 
(primary and mirror-image) to calling cetacean(s) are determined, the 
bearings will be relayed to the visual observer to help him/her sight 
the calling animal(s).
    The PAM system consists of hardware (i.e., hydrophones) and 
software. The ``wet end'' of the system consists of a towed hydrophone 
array that is connected to the vessel by a tow cable. The 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). L-DEO will deploy the array from a winch located on the back deck. 
A deck cable will connect the tow cable to the electronics unit in the 
main computer lab 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 PSAO, an expert bioacoustician with primary responsibility for 
PAM will be aboard the Langseth in addition to the four PSVOs. The PSAO 
will monitor the towed hydrophones 24 h per day during airgun 
operations and during most periods when the Langseth is underway while 
the airguns are not operating. However, PAM may not be possible if 
damage occurs to both the primary and back-up hydrophone arrays during 
operations. The primary PAM streamer on the Langseth is a digital 
hydrophone streamer. Should the digital streamer fail, back-up systems 
should include an analog spare streamer and a hull-mounted hydrophone.
    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. The other PSVOs 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 on duty will contact the visual 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. 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.
    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

[[Page 4783]]

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 and turtles in the area where the seismic study is conducted.
    4. Information to compare the distance and distribution of marine 
mammals and turtles 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.

Proposed Reporting

    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 and turtles near the 
operations. The report will provide full documentation of methods, 
results, and interpretation pertaining to all monitoring. The 90-day 
report will summarize the dates and locations of seismic operations, 
and all marine mammal sightings (dates, times, locations, activities, 
associated seismic survey activities). The report will also include 
estimates of the number and nature of exposures that could result in 
``takes'' of marine mammals by harassment or in other ways.
    In the unanticipated event that the specified activity clearly 
causes the take of a marine mammal in a manner prohibited by the IHA 
(if issued), such as an injury (Level A harassment), serious injury or 
mortality (e.g., ship-strike, gear interaction, and/or entanglement), 
L-DEO shall immediately cease the specified activities and immediately 
report the incident to the Chief of the Permits and Conservation 
Division, Office of Protected Resources, NMFS, at 301-427-8401 and/or 
by email to [email protected] and [email protected] and the NMFS 
Pacific Islands Regional Stranding Coordinator at 808-944-2269 
([email protected]). The report must include the following 
information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Name and type of vessel involved;
     Vessel's speed during and leading up to the incident;
     Description of the incident;
     Status of all sound source use in the 24 hours preceding 
the incident;
     Water depth;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, and visibility);
     Description of all marine mammal observations in the 24 
hours preceding the incident;
     Species identification or description of the animal(s) 
involved;
     Fate of the animal(s); and
     Photographs or video footage of the animal(s) (if 
equipment is available).
    Activities shall not resume until NMFS is able to review the 
circumstances of the prohibited take. NMFS shall work with L-DEO to 
determine what is necessary to minimize the likelihood of further 
prohibited take and ensure MMPA compliance. L-DEO may not resume their 
activities until notified by NMFS via letter, email, or telephone.
    In the event that L-DEO discovers an injured or dead marine mammal, 
and the lead PSVO determines that the cause of the injury or death is 
unknown and the death is relatively recent (i.e., in less than a 
moderate state of decomposition as described in the next paragraph), L-
DEO will immediately report the incident to the Chief of the Permits 
and Conservation Division, Office of Protected Resources, NMFS, at 301-
427-8401 and/or by email to [email protected] and 
[email protected] and the NMFS Pacific Islands Regional Stranding 
Coordinator at 808-944-2269 ([email protected]). The report must 
include the same information identified in the paragraph above this 
section. Activities may continue while NMFS reviews the circumstances 
of the incident. NMFS will work with L-DEO to determine whether 
modifications in the activities are appropriate.
    In the event that L-DEO discovers an injured or dead marine mammal, 
and the lead PSVO determines that the injury or death is not associated 
with or related to the activities authorized in the IHA (e.g., 
previously wounded animal, carcass with moderate to advanced 
decomposition, or scavenger damage), L-DEO will report the incident to 
the Chief of the Permits and Conservation Division, Office of Protected 
Resources, NMFS, at 301-427-8401 and/or by email to 
[email protected] and [email protected] and the NMFS Pacific 
Islands Regional Stranding Coordinator at 808-944-2269 
([email protected]), within 24 hours of the discovery. L-DEO 
will provide photographs or video footage (if available) or other 
documentation of the stranded animal sighting to NMFS.

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 proposed to be authorized as a 
result of the marine geophysical survey in the northwestern Pacific 
Ocean. Acoustic stimuli (i.e., increased underwater sound) generated 
during the operation of the seismic airgun array may have the potential 
to cause marine mammals in the survey area to be exposed to sounds at 
or greater than 160 dB or cause temporary, short-term changes in 
behavior. 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.
    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.

[[Page 4784]]

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 1,216 km (755.6 mi) of 
survey lines on the Shatsky Rise in the northwestern Pacific Ocean.
    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.
    Density data on 18 marine mammal species in the Shatsky Rise area 
are available from two sources using conventional line transect 
methods: Japanese sighting surveys conducted since the early 1980s, and 
fisheries observers in the high-seas driftnet fisheries during 1987-
1990 (see Table 3 in L-DEO's application).
    For the 16 other marine mammal species that could be encountered in 
the proposed survey area, data from the western North Pacific right 
whale are not available (see Table 3 in L-DEO's application). L-DEO is 
not aware of any density estimates for three of those species--Hubb's 
(Mesoplodon carlhubbsi), Stejneger's (Mesoplodon stejnegeri), and 
gingko-toothed beaked whales (Mesoplodon ginkgodens). For the remaining 
13 species out of the 16, (see Table 3 in L-DEO's application), density 
estimates are available from other areas of the Pacific: 11 species 
from the offshore stratum of the 2002 Hawaiian Islands survey (Barlow, 
2006) and two species from surveys of the California Current ecosystem 
off the U.S. west coast between 1991 and 2005 (Barlow and Forney, 
2007). Those estimates are based on standard line-transect protocols 
developed by NMFS' Southwest Fisheries Science Center (SWFSC).
    Densities for 14 species are available from Japanese sighting 
surveys in the Shatsky Rise survey area. Miyashita (1993a) provided 
estimates for six dolphin species in this area that have been taken in 
the Japanese drive fisheries. The densities used here are Miyashita's 
(1993a) estimates for the `Eastern offshore' survey area (30-42[deg] N, 
145[deg]-180[deg] E). Kato and Miyashita (1998) provided estimates for 
sperm whale densities from Japanese sightings data during 1982 to 1996 
in the western North Pacific (20-50[deg] N, 130[deg]-180[deg] E), and 
Hakamada et al. (2004) provided density estimates for sei whales during 
August through September in the JARPN II sub-areas 8 and 9 (35-50[deg] 
N, 150-170[deg] E excluding waters in the Exclusive Economic Zone of 
Russia) during 2002 and 2003. L-DEO used density estimates during 1994 
through 2007 for minke whales at 35-40[deg] N, 157-170[deg] E from 
Hakamada et al. (2009), density estimates during 1998 through 2002 for 
Bryde's whales at 31-43[deg] N, 145-165[deg] E from Kitakado et al. 
(2008), and density estimates during 1994-2007 for blue, fin, humpback, 
and North Pacific right whales at 31-51[deg] N, 140-170[deg] E from 
Matsuoka et al. (2009).
    For four species (northern fur seal, Dall's porpoise, Pacific 
white-sided dolphin (Lagenorhynchus obliquidens), northern right-whale 
dolphin (Lissodelphis borealis)), estimates of densities in the Shatsky 
Rise area are available from sightings data collected by observers in 
the high-seas driftnet fisheries during 1987 through 1990 (Buckland et 
al., 1993). Those data were analyzed for 5[deg] x 5[deg] blocks, and 
the densities used here are from blocks for which available data 
overlap the proposed survey area. In general, those data represent the 
average annual density in the northern half of the Shatsky Rise survey 
area (35-40[deg] N).
    The densities mentioned above had been corrected by the original 
authors for detectability bias and, with the exception of Kitakado et 
al. (2008) and Hakamada et al. (2009), for availability bias. 
Detectability bias is associated with diminishing sightability with 
increasing lateral distance from the track line [f(0)]. Availability 
bias refers to the fact that there is less than a 100 percent 
probability of sighting an animal that is present along the survey 
track line, and it is measured by g(0).
    There is some uncertainty about the accuracy of the density data 
from the Japanese Whale Research Program under Special Permit (JARPN/
JARPN II). For example, The available densities in Miyashita (1993a) 
and Buckland et al. (1993) are from the 1980s; although these densities 
represent the best available information for the Shatsky Rise area at 
present, they will be biased if abundance or distributions of those 
species have changed since the data were collected. Therefore, there is 
uncertainty with respect to the expected marine mammal densities during 
this time. However, the approach used here is based on the best 
available data.
    The estimated numbers of individuals potentially exposed are based 
on the 160-dB re: 1 [mu]Pa criterion for all cetaceans (see Table 3 in 
this notice). It is assumed that marine mammals exposed to airgun 
sounds that strong might change their behavior sufficiently to be 
considered ``taken by harassment.''
    L-DEO's estimates of exposures to various sound levels assume that 
the proposed surveys will be completed; in fact, the ensonified areas 
calculated using the planned number of line-kilometers have been 
increased by 25 percent to accommodate turns, lines that may need to be 
repeated, equipment testing, etc. As is typical during 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 exclusion zone will result in 
the shutdown of seismic operations as a mitigation measure. Thus, the 
following estimates of the numbers of marine mammals potentially 
exposed to 160-dB re 1 [mu]Pa sounds are precautionary, and probably 
overestimate the actual numbers of marine mammals that might be 
involved. These estimates 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 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 majority of seismic lines are widely spaced in the survey area, so 
few individual mammals would be exposed numerous times during the 
survey. The area including overlap is only 1.01 times the area 
excluding overlap, so a marine mammal that stayed in the survey area 
during the entire survey could be exposed only once. However, it is 
unlikely that a particular animal would stay in the area during the 
entire survey.
    The number of different individuals potentially exposed to received 
levels

[[Page 4785]]

greater than or equal to 160 re: 1 [mu]Pa was calculated by 
multiplying:
    (1) The expected species density, times;
    (2) The anticipated area to be ensonified to that level during 
airgun operations excluding overlap, which is approximately 10,971 
square kilometers (km\2\) (4,235.9 square miles (mi\2\)).
    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 
in this document) around each seismic line, and then calculating the 
total area within the buffers. Areas of overlap were included only once 
when estimating the number of individuals exposed. Applying this 
approach, approximately 9,229 km\2\ (3,563 mi\2\) (11,536 km\2\; 4,454 
mi\2\ including the 25 percent contingency) would be within the 160-dB 
isopleth on one or more occasions during the survey. Because this 
approach does not allow for turnover in the mammal populations in the 
study area during the course of the survey, the actual number of 
individuals exposed could be underestimated. However, 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.
    The total 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 during the survey is 7,354 (see Table 3). That 
total includes 74 baleen whales, 39 of which are endangered: 5 humpback 
whales or 0.53% of the regional population, 21 sei whales (0.21%), 9 
fin whales (0.05%), and 4 blue whales (0.13%). In addition, 12 sperm 
whales (also listed as endangered under the ESA) or 0.04% of the 
regional population could be exposed during the survey, and 108 beaked 
whales including Cuvier's, Longman's, Baird's, and Blainville's beaked 
whales. Most (96 percent) of the cetaceans potentially exposed are 
delphinids; short-beaked common, striped, pantropical spotted, and 
Pacific white-sided dolphins are estimated to be the most common 
species in the area, with estimates of 3,569 (0.12% of the regional 
population), 1,374 (0.24%), 812 (0.19%), and 420 (0.04%) exposed to 
greater than or equal to 160 dB re: 1 [mu]Pa, respectively.

  Table 3--Estimates of the Possible Numbers of Marine Mammals Exposed to Different Sound Levels During L-DEO's
                Seismic Survey in the Northwestern Pacific Ocean During March Through April, 2012
----------------------------------------------------------------------------------------------------------------
                                                            Estimated number
                                                             of individuals     Requested or       Approximate
                          Species                           exposed to sound    adjusted take      percent of
                                                            levels >= 160 dB    authorization       regional
                                                             re: 1 [mu]Pa\1\                     population \3\
----------------------------------------------------------------------------------------------------------------
North Pacific right whale.................................                 0             \2\ 2              0.23
Humpback whale............................................                 5                 5              0.53
Minke whale...............................................                29                29              0.12
Bryde's whale.............................................                 6                 6              0.03
Sei whale.................................................                21                21              0.21
Fin whale.................................................                 9                 9              0.05
Blue whale................................................                 4                 4              0.13
Sperm whale...............................................                12                12              0.04
Pygmy sperm whale.........................................                37                37              N.A.
Dwarf sperm whale.........................................                90                90             <0.01
Cuvier's beaked whale.....................................                78                78              0.39
Baird's beaked whale......................................                10                10              N.A.
Longman's beaked whale....................................                 5            \3\ 18              N.A.
Blainville's beaked whale.................................                15                15              0.06
Rough-toothed dolphin.....................................                36                36              0.02
Bottlenose dolphin........................................               277               277              0.16
Pantropical spotted dolphin...............................               812               812              0.19
Spinner dolphin...........................................                10            \2\ 32             <0.01
Striped dolphin...........................................              1374              1374              0.24
Fraser's dolphin..........................................                53           \2\ 286              0.02
Short-beaked common dolphin...............................              3569              3569              0.12
Pacific white-sided dolphin...............................               420               420              0.04
Northern right whale dolphin..............................                 5                 5             <0.01
Risso's dolphin...........................................               125               125              0.01
Melon-headed whale........................................                15            \2\ 89              0.03
False killer whale........................................                24                24              0.15
Killer whale..............................................                 2                73              0.02
Short-finned pilot whale..................................                58            \2\ 65              0.11
Dall's porpoise...........................................               253               253              0.02
Northern fur seal.........................................                21                21             <0.01
----------------------------------------------------------------------------------------------------------------
\1\ Estimates are based on densities in Table 3 and an ensonified area (including 25% contingency 11,536 km\2\).
\2\ Requested Take Authorization increased to mean group size from density sources in Table 3 of L-DEO's
  application.
\3\ Regional population size estimates are from Table 3 of L-DEO's application; NA means not available.

Encouraging and Coordinating Research

    L-DEO and NSF will coordinate the planned marine mammal monitoring 
program associated with the seismic survey in the northwestern Pacific 
Ocean with other parties that may have interest in the area and/or be 
conducting marine mammal studies in the same region during the seismic 
survey.

[[Page 4786]]

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.'' In making a negligible impact determination, 
NMFS considers:
    (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.
    For reasons stated previously in this document, the specified 
activities associated with the marine seismic survey are not likely to 
cause PTS, or other non-auditory injury, serious injury, or death 
because:
    (1) The likelihood that, given sufficient notice through relatively 
slow ship speed, marine mammals are expected to move away from a noise 
source that is annoying prior to its becoming potentially injurious;
    (2) The potential for temporary or permanent hearing impairment is 
relatively low and would likely be avoided through the incorporation of 
the required monitoring and mitigation measures (described previously 
in this document);
    (3) The fact that cetaceans would have to be closer than 940 m 
(3,084 ft) in deep water when the 36-airgun array is in use at 9 m 
(29.5 ft) tow depth, and 40 m (131.2 ft) in deep water when the single 
airgun is in use at 9 m from the vessel to be exposed to levels of 
sound believed to have even a minimal chance of causing PTS; and
    (4) The likelihood that marine mammal detection ability by trained 
PSVOs is high at close proximity to the vessel.
    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 by NMFS. Only short-term behavioral 
disturbance is anticipated to occur due to the brief and sporadic 
duration of the survey activities. Table 3 of this document outlines 
the number of requested Level B harassment takes that are anticipated 
as a result of these activities. Due to the nature, degree, and context 
of Level B (behavioral) harassment anticipated and described (see 
``Potential Effects on Marine Mammals'' section in this notice), the 
activity is not expected to impact rates of recruitment or survival for 
any affected species or stock. Additionally, the seismic survey will 
not adversely impact marine mammal habitat.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (i.e., 24 hr cycle). 
Behavioral reactions to noise exposure (such as disruption of critical 
life functions, displacement, or avoidance of important habitat) are 
more likely to be significant if they last more than one diel cycle or 
recur on subsequent days (Southall et al., 2007). While seismic 
operations are anticipated to occur on consecutive days, the entire 
duration of the survey is not expected to last more than approximately 
23 days (i.e., 7 days of seismic operations, 16 days of transit) and 
the Langseth will be continuously moving along planned tracklines that 
are geographically spread-out. Therefore, the seismic survey will be 
increasing sound levels in the marine environment in a relatively small 
area surrounding the vessel, which is constantly travelling over far 
distances, for a relatively short time period (i.e., one week) in the 
study area.
    Of the 34 marine mammal species under NMFS' jurisdiction that are 
known to occur or likely to occur in the study area, six of these 
species are listed as endangered under the ESA: the blue, fin, 
humpback, north Pacific right, sei, and sperm whales. These species are 
also categorized as depleted under the MMPA. L-DEO has requested 
authorized take for the six listed species. To protect these animals 
(and other marine mammals in the study area), L-DEO must cease or 
reduce airgun operations if animals enter designated zones. No injury, 
serious injury, or mortality is expected to occur and due to the 
nature, degree, and context of the Level B harassment anticipated. The 
activity is not expected to impact rates of recruitment or survival.
    As mentioned previously, NMFS estimates that 30 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, less than one percent) relative to the regional 
population size. NMFS provided the population estimates for the marine 
mammal species that may be taken by Level B harassment in Table 2 of 
this document.
    NMFS' practice has been to apply the 160 dB re: 1 [micro]Pa 
received level threshold for underwater impulse sound levels to 
determine whether take by Level B harassment occurs. Southall et al. 
(2007) provides a severity scale for ranking observed behavioral 
responses of both free-ranging marine mammals and laboratory subjects 
to various types of anthropogenic sound (see Table 4 in Southall et al. 
[2007]).
    NMFS has preliminarily determined, provided that the aforementioned 
mitigation and monitoring measures are implemented, that the impact of 
conducting a marine seismic survey on the Shatsky Rise in the 
northwestern Pacific Ocean, March to April, 2012, may result, at worst, 
in a temporary modification in behavior and/or low-level physiological 
effects (Level B harassment) of small numbers of certain species of 
marine mammals. See Table 3 for the requested authorized take numbers 
of cetaceans.
    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 of marine mammals; and that impacts to 
affected species or stocks of marine mammals have been mitigated to the 
lowest level practicable.

[[Page 4787]]

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

    Section 101(a)(5)(D) of the MMPA also requires NMFS to determine 
that the authorization will not have an unmitigable adverse effect on 
the availability of marine mammal species or stocks for subsistence 
use. There are no relevant subsistence uses of marine mammals in the 
study area (Shatsky Rise, northwestern Pacific Ocean) 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 blue, fin, humpback, north Pacific right, sei, and sperm whales. L-
DEO did not request take of endangered western north Pacific gray 
whales because of the low likelihood of encountering these species 
during the cruise.
    Under section 7 of the ESA, NSF has initiated formal consultation 
with the NMFS', Office of Protected Resources, Endangered Species Act 
Interagency Cooperation Division, on this proposed seismic survey. 
NMFS' Office of Protected Resources, Permits and Conservation Division, 
had initiated formal consultation under section 7 of the ESA with NMFS' 
Office of Protected Resources, Endangered Species Act Interagency 
Cooperation Division, to obtain a Biological Opinion (BiOp) evaluating 
the effects of issuing an IHA for 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' BiOp issued to 
both NSF and NMFS' Office of Protected Resources.

National Environmental Policy Act (NEPA)

    To meet NMFS' National Environmental Policy Act (NEPA; 42 U.S.C. 
4321 et seq.) requirements for the issuance of an IHA to L-DEO, NMFS 
will prepare an Environmental Assessment (EA) titled ``Issuance of an 
Incidental Harassment Authorization to the Lamont-Doherty Earth 
Observatory to Take Marine Mammals by Harassment Incidental to a Marine 
Geophysical Survey in the Northwest Pacific Ocean, March through April, 
2012.'' This EA will incorporate the NSF's Environmental Analysis 
Pursuant To Executive Order 12114 (NSF, 2010) and an associated report 
(Report) prepared by LGL Limited Environmental Research Associates 
(LGL) for NSF, titled, ``Environmental Assessment of a Marine 
Geophysical Survey by the R/V Marcus G. Langseth in the Northwest 
Pacific Ocean, March--April, 2012,'' by reference pursuant to 40 CFR 
1502.21 and NOAA Administrative Order (NAO) 216-6 Sec.  5.09(d). Prior 
to making a final decision on the IHA application, NMFS will make a 
decision of whether or not to issue a Finding of No Significant Impact 
(FONSI).

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
authorize the take of marine mammals incidental to L-DEO's proposed 
marine seismic survey in the northwest Pacific Ocean, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated. The duration of the IHA would not exceed one year 
from the date of its issuance.

Information Solicited

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

    Dated: January 25, 2012.
Helen M. Golde,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2012-2076 Filed 1-30-12; 8:45 am]
BILLING CODE 3510-22-P