[Federal Register Volume 76, Number 146 (Friday, July 29, 2011)]
[Notices]
[Pages 45518-45540]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2011-19244]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XA507


Takes of Marine Mammals Incidental to Specified Activities; Low-
Energy Marine Geophysical Survey in the Western Tropical Pacific Ocean, 
November to December, 2011

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

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

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SUMMARY: NMFS has received an application from the Scripps Institution 
of Oceanography (SIO) for an Incidental Harassment Authorization (IHA) 
to take marine mammals, by harassment, incidental to conducting a low-
energy marine geophysical (i.e., seismic) survey in the western 
tropical Pacific Ocean, November to December, 2011. Pursuant to the 
Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its 
proposal to issue an IHA to SIO to incidentally harass, by Level B 
harassment only, 19 species of marine mammals during the specified 
activity.

DATES: Comments and information must be received no later than August 
29, 2011.

ADDRESSES: Comments on the application should be addressed to P. 
Michael Payne, Chief, Permits, Conservation and Education Division, 
Office of Protected Resources, National Marine Fisheries Service, 1315 
East-West Highway, Silver Spring, MD 20910. The mailbox address for 
providing e-mail comments is [email protected]. NMFS is not 
responsible for e-mail comments sent to addresses other than the one 
provided here. Comments sent via e-mail, including all attachments, 
must not exceed a 10-megabyte file size.
    All comments received are a part of the public record and will 
generally be posted to http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications without change. All Personal Identifying 
Information (for example, name, address, etc.) voluntarily submitted by 
the commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.
    A copy of the application containing a list of the references used 
in this document may be obtained by writing to the above address, 
telephoning the contact listed here (see FOR FURTHER INFORMATION 
CONTACT) or visiting the Internet at: http://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications.
    The National Science Foundation (NSF) has prepared a draft 
``Environmental Assessment of a Marine Geophysical Survey by the R/V 
Thompson in the western tropical Pacific Ocean November-December 2011 
(EA).'' The draft EA incorporates an ``Environmental Assessment of a 
Low-Energy Marine Geophysical Survey by the R/V Thompson in the Western 
Tropical Pacific Ocean, November-December 2011,'' prepared by LGL Ltd., 
Environmental Research Associates (LGL), on behalf of NSF and SIO, 
which is also available at the same Internet address. Documents cited 
in this notice may be viewed, by appointment, during regular business 
hours, at the aforementioned address.

FOR FURTHER INFORMATION CONTACT: Howard Goldstein or Jolie Harrison, 
Office of Protected Resources, NMFS, 301-427-8401.

SUPPLEMENTARY INFORMATION:

Background

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

[[Page 45519]]

    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 June 14, 2011, from SIO for the 
taking by harassment, of marine mammals, incidental to conducting a 
low-energy marine seismic survey in the western tropical Pacific Ocean. 
SIO, a part of the University of California, in collaboration with 
University of Washington (UW), Woods Hole Oceanographic Institution 
(WHOI), Texas A&M University (TAMU), and Kutztown University, plans to 
conduct a magnetic and seismic study of the Hawaiian Jurassic crust 
onboard an oceanographic research vessel in the western tropical 
Pacific Ocean north of the Marshall Islands for approximately 32 days. 
The survey will use a pair of Generator Injector (GI) airguns each with 
a discharge volume of 105 cubic inches (in\3\). SIO plans to conduct 
the proposed survey from approximately November 5 to December 17, 2011. 
The proposed seismic survey will be conducted partly in international 
waters and partly in the Exclusive Economic Zone (EEZ) of Wake Island 
(U.S.), and possibly in the EEZ of the Republic of the Marshall 
Islands.
    SIO plans to use one source vessel, the R/V Thomas G. Thompson 
(Thompson) and a seismic airgun array to collect seismic reflection and 
refraction profiles from the Hawaiian Jurassic crust in the western 
tropical Pacific Ocean. In addition to the proposed operations of the 
seismic airgun array, SIO 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 SIO has requested an authorization 
to take 19 species of marine mammals by Level B harassment. Take is not 
expected to result from the use of the MBES or SBP, for reasons 
discussed in this notice; nor is take expected to result from collision 
with the vessel because it is a single vessel moving at a relatively 
slow speed during seismic acquisition within the survey, for a 
relatively short period of time (approximately 39 days). It is likely 
that any marine mammal would be able to avoid the vessel.

Description of the Proposed Specified Activity

    SIO's proposed seismic survey in the western tropical Pacific 
Ocean, as part of an integrated magnetic and seismic study of the 
Hawaiian Jurassic crust, will take place for approximately 32 days in 
November to December, 2011 (see Figure 1 of the IHA application). The 
proposed seismic survey will take place in water depths ranging from 
approximately 2,000 to 6,000 meters (m) (6,561.7 to 19,685 feet [ft]) 
and consist of approximately 1,600 kilometers (km) (863.9 nautical 
miles [nmi]) of transect lines in the study area. The survey will take 
place in the area 13[deg] to 23[deg] North, 158[deg] to 172[deg] East, 
just north of the Marshall Islands. The project is scheduled to occur 
from approximately November 5 to December 17, 2011. Some minor 
deviation from these dates is possible, depending on logistics and 
weather.
    The goal of the proposed research is to define the global nature 
and significance of variations in intensity and direction of the 
Earth's magnetic field during the Jurassic time period (approximately 
145 to 180 million years ago), which appears to have been a period of 
sustained low intensity and rapid directional changes or polarity 
reversals compared to other periods in Earth's magnetic field history. 
Access to Jurassic-aged crust with good magnetic signals is very 
limited, with the best continuous records in ocean crust, but only one 
area of the ocean floor has been measured to date: the western Pacific 
Japanese magnetic lineations. To properly assess the global 
significance of the variations and to eliminate local crustal and 
tectonic complications, it is necessary to measure Jurassic magnetic 
signals in a different area of the world. The proposed study will 
attempt to verify the unusual behavior of the Jurassic geomagnetic 
field and test whether it was behaving in a globally coherent way by 
conducting a near-bottom marine magnetic field survey of Pacific 
Hawaiian Jurassic crust located between Hawaii and Guam.
    Widespread, younger, Cretaceous-aged (65 to 140 million years ago) 
volcanism overprinted much of the western Pacific, so it is important 
to know the extent of Cretaceous-aged volcanic crust. This will be 
assessed by carrying out a seismic reflection and refraction survey of 
the Hawaiian Jurassic crust. First, the autonomous underwater vehicle 
(AUV) Sentry and a simultaneously deployed deep-towed magnetometer 
system will acquire two parallel profiles of the near-bottom crustal 
magnetic field 10 km (5.4 nmi) apart and approximately 800 km (432 nmi) 
long. More information on the AUV Sentry is available at http://www.whoi.edu/page.do?pid=38098. Second, the seismic survey will be 
conducted using airguns, a hydrophone streamer, and sonobuoys directly 
over the same profile as the AUV magnetic survey.
    The survey will involve one source vessel, the Thompson. For the 
seismic component of the research program, the Thompson will deploy an 
array of two low-energy Sercel Generator Injector (GI) airguns as an 
energy source (each with a discharge volume of 105 in\3\) at a tow 
depth of 3 m (9.8 ft). The acoustic receiving system will consist of an 
800 m (2,624.7 ft), 48 channel hydrophone streamer and directional, 
passive sonobuoys. Over the course of the seismic operations, 50 Ultra 
Electronics AN/SSQ-53D(3) directional, passive sonobuoys will be 
deployed from the vessel. The sonobuoys consist of a hydrophone, 
electronics, and a radio transmitter. As the airgun is towed along the 
survey lines, the hydrophone streamer and sonobuoys will receive the 
returning acoustic signals and transfer the data to the on-board 
processing system. The seismic signal is measured by the sonobuoy's 
hydrophone and transmitted by radio back to the source vessel. The 
sonobuoys are expendable, and after a pre-determined time (usually 
eight hours), they self-scuttle and sink to the ocean bottom.
    The survey lines will be within the area enclosed by red lines in 
Figure 1 of the IHA application, but the exact locations of the survey 
lines will be determined during transit after observing the location of 
the appropriate magnetic lineation by surface-towed magnetometer. 
Magnetic and seismic data acquisition will alternate on a daily basis; 
seismic surveys will take place while the AUV used to collect magnetic 
data is on deck to recharge its batteries. In addition to the 
operations of the airgun array, a Kongsberg EM300 MBES and ODEC Bathy-
2000 SBP will also be operated from the Thompson continuously 
throughout the cruise. There will be additional seismic operations 
associated with equipment testing, start-up, and possible line changes 
or repeat coverage of any areas where initial data quality is sub-
standard. In SIO's calculations, 25% has

[[Page 45520]]

been added for those contingency operations.
    All planned geophysical data acquisition activities will be 
conducted by technicians provided by SIO, with on-board assistance by 
the scientists who have proposed the study. The Principal Investigators 
are Drs. Masako Tominaga, Maurice A. Tivey, Daniel Lizarralde of WHOI, 
William W. Sager of TAMU, and Adrienne Oakley of Kutztown University. 
The vessel will be self-contained, and the crew will live aboard the 
vessel for the entire cruise.

Vessel Specifications

    The Thompson is operated by the University of Washington under a 
charter agreement with the U.S. Office of Naval Research. The title of 
the vessel is held by the U.S. Navy. The Thompson will tow the two GI 
airgun array, as well as the hydrophone streamer, along predetermined 
lines.
    The vessel has a length of 83.5 m (274 ft); a beam of 16 m (52.5 
ft), and a full load draft of 5.8 m (19 ft). It is equipped with twin 
360[deg] azimuth stern thrusters each powered by a 3,000 horsepower 
(hp) DC motor and a water-jet bow thruster powered by a 1,600 hp DC 
motor. The motors are driven by up to three 1,500 kiloWatt (kW) and 
three 715 kW generators; normal operations use two 1,500 kW and one 750 
kW generator, but this changes with ship speed, sea state, and other 
variables. An operations speed of 7.4 km/hour (hr) (4 knots [kt]) will 
be used during seismic acquisition. When not towing seismic survey 
gear, the Thompson cruises at 22 km/hr (12 kt) and has a maximum speed 
of 26.9 km/hr (14.5 kt). The Thompson has a range of 24,400 km (13,175 
nmi) (the distance the vessel can travel without refueling).
    The vessel will also serve as a platform for which vessel-based 
Protected Species Observers (PSOs) will watch for marine mammals before 
and during the proposed airgun operations.

Acoustic Source Specifications

Seismic Airguns

    The Thompson will deploy and tow an array consisting of a pair of 
45 to 105 in\3\ Sercel GI airgun and a streamer containing hydrophones 
along predetermined lines. Seismic pulses will be emitted at intervals 
of five or ten seconds (s). At speeds of approximately 7.4 km/hr, the 
five to ten s spacing corresponds to shot intervals of approximately 10 
to 20 m (32.8 to 65.6 ft).
    The generator chamber of each GI airgun, the one responsible for 
introducing the sound pulse into the ocean, is either 45 in\3\ or 105 
in\3\, depending on how it is configured. The injector chamber injects 
air into the previously-generated bubble to maintain its shape, and 
does not introduce more sound into the water. The two GI airguns will 
be towed 8 m (26.2 ft) apart side-by-side, 21 m (68.9 ft) behind the 
Thompson, at a depth of 3 m (9.8 ft). Depending on the configuration, 
the total effective volume will be 90 in\3\ or 210 in\3\. As a 
precautionary measure, SIO assumes that the larger volume will be used.
    As the GI airguns are towed along the survey lines, the towed 
hydrophone array in the streamer and the sonobuoys receive the 
reflected signals and transfer the data to the on-board processing 
system. Given the relatively short streamer length behind the vessel, 
the turning rate of the vessel while the gear is deployed is much 
higher than the limit of five degrees per minute for a seismic vessel 
towing a streamer of more typical length (much greater than 1 km [0.5 
nmi]). Thus maneuverability of the vessel is not limited much during 
operations.

Metrics Used in This Document

    This section includes a brief explanation of the sound measurements 
frequently used in the discussions of acoustic effects in this 
document. Sound pressure is the sound force per unit area, and is 
usually measured in micropascals ([mu]Pa), where 1 pascal (Pa) is the 
pressure resulting from a force of one newton exerted over an area of 
one square meter. Sound pressure level (SPL) is expressed as the ratio 
of a measured sound pressure and a reference level. The commonly used 
reference pressure level in underwater acoustics is 1 [mu]Pa, and the 
units for SPLs are dB re: 1 [mu]Pa. SPL (in decibels [dB]) = 20 log 
(pressure/reference pressure).
    SPL is an instantaneous measurement and can be expressed as the 
peak, the peak-peak (p-p), or the root mean square (rms). Root mean 
square, which is the square root of the arithmetic average of the 
squared instantaneous pressure values, is typically used in discussions 
of the effects of sounds on vertebrates and all references to SPL in 
this document refer to the root mean square unless otherwise noted. SPL 
does not take the duration of a sound into account.

Characteristics of the Airgun Pulses

    Airguns function by venting high-pressure air into the water which 
creates an air bubble. The pressure signature of an individual airgun 
consists of a sharp rise and then fall in pressure, followed by several 
positive and negative pressure excursions caused by the oscillation of 
the resulting air bubble. The oscillation of the air bubble transmits 
sounds downward through the seafloor and the amount of sound 
transmitted in the near horizontal directions is reduced. However, the 
airgun array also emits sounds that travel horizontally toward non-
target areas.
    The nominal downward-directed source levels of the airgun arrays 
used by SIO on the Thompson do not represent actual sound levels that 
can be measured at any location in the water. Rather they represent the 
level that would be found 1 m (3.3 ft) from a hypothetical point source 
emitting the same total amount of sound as is emitted by the combined 
GI airguns. The actual received level at any location in the water near 
the GI airguns will not exceed the source level of the strongest 
individual source. In this case, that will be about 234.4 dB re 1 
[mu]Pam peak, or 239.8 dB re 1 [mu]Pam peak-to-peak. However, the 
difference between rms and peak or peak-to-peak values for a given 
pulse depends on the frequency content and duration of the pulse, among 
other factors.
    Accordingly, Lamont-Doherty Earth Observatory of Columbia 
University (L-DEO) has predicted the received sound levels in relation 
to distance and direction from the two GI airgun array. A detailed 
description of L-DEO's modeling for marine seismic source arrays for 
species mitigation is provided in Appendix A of SIO's EA. These are the 
nominal source levels applicable to downward propagation. The effective 
source levels for horizontal propagation are lower than those for 
downward propagation when the source consists of numerous airguns 
spaced apart from one another.
    Appendix A of SIO's EA discusses the characteristics of the airgun 
pulses. NMFS refers the reviewers to the application and EA documents 
for additional information.

Predicted Sound Levels for the Airguns

    Received sound levels have been modeled by L-DEO for a number of 
airgun configurations, including two 105 in\3\ GI airguns, in relation 
to distance and direction from the airguns (see Figure 2 of the IHA 
application). The model does not allow for bottom interactions, and is 
most directly applicable to deep water. Based on the modeling, 
estimates of the maximum distances from the GI airguns where sound 
levels of 190, 180, and 160 dB re 1 [mu]Pa (rms) are predicted to be 
received

[[Page 45521]]

in deep water are shown in Table 1 (see Table 1 of the IHA 
application).
    Empirical data concerning the 190, 180, and 160 dB (rms) distances 
were acquired for various airgun arrays based on measurements during 
the acoustic verification studies conducted by L-DEO in the northern 
GOM in 2003 (Tolstoy et al., 2004) and 2007 to 2008 (Tolstoy et al., 
2009). Results of the 36 airgun array are not relevant for the two GI 
airguns to be used in the proposed survey. The empirical data for the 
6, 10, 12, and 20 airgun arrays indicate that, for deep water, the L-
DEO model tends to overestimate the received sound levels at a given 
distance (Tolstoy et al., 2004). Measurements were not made for the two 
GI airgun array in deep water, however, SIO proposes to use the EZ 
predicted by L-DEO's model for the proposed GI airgun operations in 
deep water, although they are likely conservative given the empirical 
proposed GI airgun operations in deep water. Using the L-DEO model, 
Table 1 (below) shows the distances at which three rms sound levels are 
expected to be received from the two GI airgun array. The 180 and 190 
dB re 1 [mu]Pa (rms) distances are the safety criteria for potential 
Level A harassment as specified by NMFS (2000) and are applicable to 
cetaceans and pinnipeds, respectively. If marine mammals are detected 
within or about to enter the appropriate EZ, the airguns will be shut-
down immediately.
    Table 1 summarizes the predicted distances at which sound levels 
(160, 180, and 190 dB [rms]) are expected to be received from the two 
GI airgun array operating in deep water depths.

  Table 1--Distances to Which Sound Levels >= 190, 180, and 160 dB re 1 [mu]Pa (rms) Could be Received in Deep
   Water During the Proposed Seismic Survey in the Western Tropical Pacific Ocean, November to December, 2011.
                             Distances Are Based on Model Results Provided by L-DEO.
----------------------------------------------------------------------------------------------------------------
                                                                                  Predicted RMS radii distances
                                             Tow                                               (m)
            Source and volume               depth         Water depth (m)       --------------------------------
                                             (m)                                   190 dB     180 dB     160 dB
----------------------------------------------------------------------------------------------------------------
Two GI airguns (105 in\3\)...............        3  Deep (> 1,000).............         20         70        670
----------------------------------------------------------------------------------------------------------------

MBES

    The Thompson will operate a Kongsberg EM 300 MBES concurrently 
during airgun operations to map characteristics of the ocean floor. The 
MBES has a hull-mounted transducer within a transducer pod that is 
located amidships. The system's normal operating frequency is 
approximately 30 kHz. The transmit fan-beam is split into either three 
or nine narrower beam sectors with independent active steering to 
correct for vessel yaw. Angular coverage is 36[deg] (in Extra Deep 
Mode, for use in water depths 3,000 to 6,000 m [9,842.5 to 19,685 ft]) 
or 150[deg] (in shallower water). The total angular coverage of 36[deg] 
to 150[deg] consists of the three or nine beams transmitted 
sequentially at each ping. Except in very deep water where the total 
beam is 36[deg] x 1[deg], the composite fan beam is 150[deg] x 1[deg], 
150[deg] x 2[deg] or 150[deg] x 4[deg] depending on water depth. The 
nine beams making up the composite fan will overlap slightly if the 
vessel yaw is less than the fore-aft width of the beam (1, 2, or 
4[deg], respectively). Achievable swath width on a flat bottom will 
normally be approximately five times the water depth. The maximum 
source level is 237 dB re 1 [mu]Pam (rms) (Hammerstad, 2005). In deep 
water (500 to 3,000 m [1,640.4 to 9,842.5 ft]), a pulse length of 5 
milliseconds (ms) is normally used, and the ping rate is mainly limited 
by the round trip travel time in the water.

SBP

    The Thompson will also operate an Ocean Data Equipment Corporation 
Bathy-2000 SBP continuously throughout the cruise simultaneously with 
the MBES to map and provide information about the sedimentary features 
and bottom topography. The SBP has a maximum 7 kilowatt (kW) transmit 
capacity into the underhull array. The energy from the SBP is directed 
downward from a 3 kHz transducer in the transducer array mounted in the 
hull of the vessel. Pulse duration ranges from 1.5 to 24 ms and the 
interval between pulses is controlled automatically by the system or 
manually by an operator depending on water depth and reflectivity of 
the bottom sediments. The system produces one sound pulse and then 
waits for its return before transmitting again. The swept (chirp) 
frequency ranges from 6 to 35 kHz. The maximum source output downward 
is 221 dB re 1 [mu]Pam (rms), but in practice, the system is rarely 
operated above 80% power level.
    NMFS expects that acoustic stimuli resulting from the proposed 
operation of the two GI airgun array has the potential to harass marine 
mammals, incidental to the conduct of the proposed seismic survey. NMFS 
expects these disturbances to be temporary and result, at worst, in a 
temporary modification in behavior and/or low-level physiological 
effects (Level B harassment) of small numbers of certain species of 
marine mammals. NMFS does not expect that the movement of the Thompson, 
during the conduct of the seismic survey, has the potential to harass 
marine mammals because of the relatively slow operation speed of the 
vessel (7.4 km/hr or 4 kt) during seismic acquisition.

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

    The Thompson is expected to depart Honolulu, Hawaii, on November 5, 
2011 and spend approximately 7 days in transit to the proposed survey 
area, 32 days alternating between acquiring magnetic and seismic data, 
and approximately 3 days in transit, arriving at Apra Harbor, Guam, on 
December 17, 2011. Seismic operations will be conducted for a total of 
approximately 16 days. Some minor deviation from this schedule is 
possible, depending on logistics and weather. The survey will encompass 
the area approximately 13[deg] to 23[deg] North, approximately 158[deg] 
to 172[deg] East, just north of the Marshall Islands (see Figure 1 of 
the IHA application). Water depths in the survey area generally range 
from approximately 2,000 to 6,000 m (6,561.7 to 19,685 ft); Wake Island 
is included in the survey area. The seismic survey will be conducted 
partly in international waters and partly in the EEZ of Wake Island 
(U.S.), and possibly in the EEZ of the Republic of the Marshall 
Islands.

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

    Twenty-six marine mammal species (19 odontocetes, 6 mysticetes, and 
one pinniped) are known to or could occur in the Marshall Islands 
Marine Eco-region (MIME) study area. Several of

[[Page 45522]]

these species are listed as endangered under the U.S. Endangered 
Species Act of 1973 (ESA; 16 U.S.C. 1531 et seq.), including the 
humpback (Megaptera novaeangliae), sei (Balaenoptera borealis), fin 
(Balaenoptera physalus), blue (Balaenoptera musculus), and sperm 
(Physeter macrocephalus) whales, as well as the Hawaiian monk seal 
(Monachus schauinslandi). The North Pacific right whale (Eubalaena 
japonica), listed as endangered under the ESA, was historically 
distributed throughout the North Pacific Ocean north of 35[deg] North 
and occasionally occurred as far south as 20[deg] North. Whaling 
records indicate that the MIME was not part of its range (Townsend, 
1935).
    The dugong (Dugong dugon), also listed as endangered under the ESA, 
is distributed in shallow coastal waters throughout most of the Indo-
Pacific region between approximately 27[deg] North and South of the 
equator (Marsh, 2008). Its historical range extended to the Marshall 
Islands (Nair et al., 1975). However, the dugong is declining or 
extinct in at least one third of its range and no long occurs in the 
MIME (Marsh, 2008). The dugong is managed by the U.S. Fish and Wildlife 
Service (USFWS) and is not considered further in this analysis; all 
others are managed by NMFS.
    The marine mammals that occur in the proposed survey area belong to 
three taxonomic groups: odontocetes (toothed cetaceans, such as 
dolphins), mysticetes (baleen whales), and pinnipeds (seals, sea lions, 
and walrus). Cetaceans are the subject of the IHA application to NMFS.
    Table 2 (below) presents information on the abundance, 
distribution, population status, conservation status, and density of 
the marine mammals that may occur in the proposed survey area during 
November to December, 2011.
BILLING CODE 3510-22-P

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[GRAPHIC] [TIFF OMITTED] TN29JY11.003


[[Page 45524]]


[GRAPHIC] [TIFF OMITTED] TN29JY11.004


[[Page 45525]]


[GRAPHIC] [TIFF OMITTED] TN29JY11.005

BILLING CODE 3510-22-C
    Refer to Section III and IV of SIO'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 SIO calculated the estimated densities for the marine mammals in 
the proposed survey area. NMFS has reviewed these data and determined 
them to be the best available scientific information for the purposes 
of the proposed IHA.

Potential Effects on Marine Mammals

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

Tolerance to Sound

    Studies on marine mammals' tolerance to sound in the natural 
environment are relatively rare. Richardson et al. (1995) defines 
tolerance as the occurrence of marine mammals in areas where they are 
exposed to human activities or man-made noise. In many cases, tolerance 
develops by the animal habituating to the stimulus (i.e., the gradual 
waning of responses to a repeated or ongoing stimulus) (Richardson, et 
al., 1995; Thorpe, 1963), but because of ecological or physiological 
requirements, many marine animals may need to remain in areas where 
they are exposed to chronic stimuli (Richardson, et al., 1995).
    Numerous studies have shown that pulsed sounds from airguns are 
often readily detectable in the water at distances of many kilometers. 
Malme et al., (1985) studied the responses of humpback whales on their 
summer feeding grounds in southeast Alaska to seismic pulses from a 
airgun with a total volume of 100 in \3\. They noted that the whales 
did not exhibit persistent avoidance when exposed to the airgun and 
concluded that there was no clear evidence of avoidance, despite the 
possibility of subtle effects, at received levels up to 172 dB re 1 
[mu]Pa.
    Weir (2008) observed marine mammal responses to seismic pulses from 
a 24 airgun array firing a total volume of either 5,085 in \3\ or 3,147 
in \3\ in Angolan waters between August 2004 and May 2005. She recorded 
a total of 207 sightings of humpback whales (n = 66), sperm whales (n = 
124), and Atlantic spotted dolphins (n = 17) and reported that there 
were no significant differences in encounter rates (sightings/hr) for 
humpback and sperm whales according to the airgun array's operational 
status (i.e., active versus silent).

Masking of Natural Sounds

    The term masking refers to the inability of a subject to recognize 
the occurrence of an acoustic stimulus as a result of the interference 
of another acoustic stimulus (Clark et al., 2009). Introduced 
underwater sound may, through masking, reduce the effective 
communication distance of a marine mammal species if the frequency of 
the source is close to that used as a signal by the marine mammal, and 
if the anthropogenic sound is present for a significant fraction of the 
time (Richardson et al., 1995).
    Masking effects of pulsed sounds (even from large arrays of 
airguns) on marine mammal calls and other natural sounds are expected 
to be limited. Because of the intermittent nature and low duty cycle of 
seismic airgun pulses, animals can emit and receive sounds in

[[Page 45526]]

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 A(4) of SIO'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, and on ringed seals (Phoca 
hispida). Less detailed data are available for some other species of 
baleen whales, small toothed whales, and sea otters, but for many 
species there are no data on responses to marine seismic surveys.
    Baleen Whales--Baleen whales generally tend to avoid operating 
airguns, but avoidance radii are quite variable (reviewed in Richardson 
et al., 1995). Whales are often reported to show no overt reactions to 
pulses from large arrays of airguns at distances beyond a few kms, even 
though the airgun pulses remain well above ambient noise levels out to 
much longer distances. However, as reviewed in Appendix A (5) of SIO's 
EA, baleen whales exposed to strong noise pulses from airguns often 
react by deviating from their normal migration route and/or 
interrupting their feeding and moving away. In the cases of migrating 
gray and bowhead whales, the observed changes in behavior appeared to 
be of little or no biological consequence to the animals (Richardson, 
et al., 1995). They simply avoided the sound source by displacing their 
migration route to varying degrees, but within the natural boundaries 
of the migration corridors.
    Studies of gray, bowhead, and humpback whales have shown that 
seismic pulses with received levels of 160 to 170 dB re 1 [mu]Pa (rms) 
seem to cause obvious avoidance behavior in a substantial fraction of 
the animals exposed (Malme et al., 1986, 1988; Richardson et al., 
1995). In many areas, seismic pulses from large arrays of airguns 
diminish to those levels at distances ranging from 4.5 to 14.5 km (2.4 
to 7.8 nmi) 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 A (5) of SIO's EA have shown that some species 
of baleen whales, notably bowhead and humpback whales, at times, show 
strong avoidance at received levels lower than 160 to 170 dB re 1 
[mu]Pa (rms).
    McCauley et al. (1998, 2000a) studied the responses of humpback 
whales off western Australia to a full-scale seismic survey with a 16 
airgun array (2,678 in \3\) and to a single airgun (20 in\3\) with 
source level of 227 dB re 1 [micro]Pa (p-p). In the 1998 study, they 
documented that avoidance reactions began at five to eight km (2.7 to 
4.3 nmi) from the array, and that those reactions kept most pods 
approximately three to four km from the operating seismic boat. In the 
2000 study, they noted localized displacement during migration of four 
to five km by traveling pods and seven to 12 km (6.5 nmi) by more 
sensitive resting pods of cow-calf pairs. Avoidance distances with 
respect to the single airgun were smaller but consistent with the 
results from the full array in terms of the received sound levels. The 
mean received level for initial avoidance of an approaching airgun was 
140 dB re 1 [mu]Pa (rms) for humpback pods containing females, and at 
the mean closest point of approach distance the received level was 143 
dB re 1 [mu]Pa (rms). The initial avoidance response generally occurred 
at distances of five to eight km from the airgun array and two km from 
the single airgun. However, some individual humpback whales, especially 
males, approached within distances of 100 to 400 m (328 to 1,312 ft), 
where the maximum received level was 179 dB re 1 [mu]Pa (rms).
    Data collected by observers during several seismic surveys in the 
Northwest Atlantic showed that sighting rates of humpback whales were 
significantly greater during non-seismic periods compared with periods 
when a full array was operating (Moulton and Holst, 2010). In addition, 
humpback whales were more likely to swim away and less likely to swim 
towards a vessel during seismic vs. non-seismic periods (Moulton and 
Holst, 2010).
    Humpback whales on their summer feeding grounds in southeast Alaska 
did not exhibit persistent avoidance when exposed to seismic pulses 
from a 1.64-L (100 in \3\) airgun (Malme et al., 1985). Some humpbacks 
seemed ``startled'' at received levels of 150 to 169 dB re 1 [mu]Pa. 
Malme et al. (1985) concluded that there was no clear evidence of 
avoidance, despite the possibility of subtle effects, at received 
levels up to

[[Page 45527]]

172 dB re 1 [mu]Pa (rms). However, Moulton and Holst (2010) reported 
that humpback whales monitored during seismic surveys in the Northwest 
Atlantic had lower sighting rates and were most often seen swimming 
away from the vessel during seismic periods compared with periods when 
airguns were silent.
    Studies have suggested that south Atlantic humpback whales 
wintering off Brazil may be displaced or even strand upon exposure to 
seismic surveys (Engel et al., 2004). The evidence for this was 
circumstantial and subject to alternative explanations (IAGC, 2004). 
Also, the evidence was not consistent with subsequent results from the 
same area of Brazil (Parente et al., 2006), or with direct studies of 
humpbacks exposed to seismic surveys in other areas and seasons. After 
allowance for data from subsequent years, there was no observable 
direct correlation between strandings and seismic surveys (IWC, 
2007:236).
    There are no data on reactions of right whales to seismic surveys, 
but results from the closely-related bowhead whale show that their 
responsiveness can be quite variable depending on their activity 
(migrating versus feeding). Bowhead whales migrating west across the 
Alaskan Beaufort Sea in autumn, in particular, are unusually 
responsive, with substantial avoidance occurring out to distances of 20 
to 30 km (10.8 to 16.2 nmi) from a medium-sized airgun source at 
received sound levels of around 120 to 130 dB re 1 [mu]Pa (Miller et 
al., 1999; Richardson et al., 1999; see Appendix A (5) of SIO'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 [mu]Pa (rms). Those findings were generally consistent with the 
results of experiments conducted on larger numbers of gray whales that 
were migrating along the California coast (Malme et al., 1984; Malme 
and Miles, 1985), and western Pacific gray whales feeding off Sakhalin 
Island, Russia (Wursig et al., 1999; Gailey et al., 2007; Johnson et 
al., 2007; Yazvenko et al., 2007a, b), along with data on gray whales 
off British Columbia (Bain and Williams, 2006).
    Various species of Balaenoptera (blue, sei, fin, and minke whales) 
have occasionally been seen in areas ensonified by airgun pulses 
(Stone, 2003; MacLean and Haley, 2004; Stone and Tasker, 2006), and 
calls from blue and fin whales have been localized in areas with airgun 
operations (e.g., McDonald et al., 1995; Dunn and Hernandez, 2009; 
Castellote et al., 2010). Sightings by observers on seismic vessels off 
the United Kingdom from 1997 to 2000 suggest that, during times of good 
sightability, sighting rates for mysticetes (mainly fin and sei whales) 
were similar when large arrays of airguns were shooting vs. silent 
(Stone, 2003; Stone and Tasker, 2006). However, these whales tended to 
exhibit localized avoidance, remaining significantly further (on 
average) from the airgun array during seismic operations compared with 
non-seismic periods (Stone and Tasker, 2006). Castellote et al. (2010) 
reported that singing fin whales in the Mediterranean moved away from 
an operating airgun array.
    Ship-based monitoring studies of baleen whales (including blue, 
fin, sei, minke, and humpback whales) in the Northwest Atlantic found 
that overall, this group had lower sighting rates during seismic vs. 
non-seismic periods (Moulton and Holst, 2010). Baleen whales as a group 
were also seen significantly farther from the vessel during seismic 
compared with non-seismic periods, and they were more often seen to be 
swimming away from the operating seismic vessel (Moulton and Holst, 
2010). Blue and minke whales were initially sighted significantly 
farther from the vessel during seismic operations compared to non-
seismic periods; the same trend was observed for fin whales (Moulton 
and Holst, 2010). Minke whales were most often observed to be swimming 
away from the vessel when seismic operations were underway (Moulton and 
Holst, 2010).
    Data on short-term reactions by cetaceans to impulsive noises are 
not necessarily indicative of long-term or biologically significant 
effects. It is not known whether impulsive sounds affect reproductive 
rate or distribution and habitat use in subsequent days or years. 
However, gray whales have continued to migrate annually along the west 
coast of North America with substantial increases in the population 
over recent years, despite intermittent seismic exploration (and much 
ship traffic) in that area for decades (Appendix A in Malme et al., 
1984; Richardson et al., 1995; Allen and Angliss, 2010). The western 
Pacific gray whale population did not seem affected by a seismic survey 
in its feeding ground during a previous year (Johnson et al., 2007). 
Similarly, bowhead whales have continued to travel to the eastern 
Beaufort Sea each summer, and their numbers have increased notably, 
despite seismic exploration in their summer and autumn range for many 
years (Richardson et al., 1987; Allen and Angliss, 2010).
    Toothed Whales--Little systematic information is available about 
reactions of toothed whales to noise pulses. Few studies similar to the 
more extensive baleen whale/seismic pulse work summarized above and (in 
more detail) in Appendix A of SIO's EA have been reported for toothed 
whales. However, there are recent systematic studies on sperm whales 
(e.g., Gordon et al., 2006; Madsen et al., 2006; Winsor and Mate, 2006; 
Jochens et al., 2008; Miller et al., 2009). There is an increasing 
amount of information about responses of various odontocetes to seismic 
surveys based on monitoring studies (e.g., Stone, 2003; Smultea et al., 
2004; Moulton and Miller, 2005; Bain and Williams, 2006; Holst et al., 
2006; Stone and Tasker, 2006; Potter et al., 2007; Hauser et al., 2008; 
Holst and Smultea, 2008; Weir, 2008; Barkaszi et al., 2009; Richardson 
et al., 2009; Moulton and Holst, 2010).
    Seismic operators and marine mammal observers on seismic vessels 
regularly see dolphins and other small toothed whales near operating 
airgun arrays, but in general there is a tendency for most delphinids 
to show some avoidance of operating seismic vessels (e.g., Goold, 
1996a, b, c; Calambokidis and Osmek, 1998; Stone, 2003; Moulton and 
Miller, 2005; Holst et al., 2006; Stone and Tasker, 2006; Weir, 2008; 
Richardson et al., 2009; Barkaszi et al., 2009; Moulton and Holst, 
2010). Some dolphins seem to be attracted to the seismic vessel and 
floats, and some ride the bow wave of the seismic vessel even when 
large arrays of airguns are firing (e.g., Moulton and Miller, 2005).

[[Page 45528]]

Nonetheless, small toothed whales more often tend to head away, or to 
maintain a somewhat greater distance from the vessel, when a large 
array of airguns is operating than when it is silent (e.g., Stone and 
Tasker, 2006; Weir, 2008; Barry et al., 2010; Moulton and Holst, 2010). 
In most cases, the avoidance radii for delphinids appear to be small, 
on the order of one km or less, and some individuals show no apparent 
avoidance. The beluga whale (Delphinapterus leucas) is a species that 
(at least at times) shows long-distance avoidance of seismic vessels. 
Aerial surveys conducted in the southeastern Beaufort Sea during summer 
found that sighting rates of beluga whales were significantly lower at 
distances 10 to 20 km compared with 20 to 30 km from an operating 
airgun array, and observers on seismic boats in that area rarely see 
belugas (Miller et al., 2005; Harris et al., 2007).
    Captive bottlenose dolphins (Tursiops truncatus) and beluga whales 
exhibited changes in behavior when exposed to strong pulsed sounds 
similar in duration to those typically used in seismic surveys 
(Finneran et al., 2000, 2002, 2005). However, the animals tolerated 
high received levels of sound before exhibiting aversive behaviors.
    Results for porpoises depend on species. The limited available data 
suggest that harbor porpoises show stronger avoidance of seismic 
operations than do Dall's porpoises (Stone, 2003; MacLean and Koski, 
2005; Bain and Williams, 2006; Stone and Tasker, 2006). Dall's 
porpoises seem relatively tolerant of airgun operations (MacLean and 
Koski, 2005; Bain and Williams, 2006), although they too have been 
observed to avoid large arrays of operating airguns (Calambokidis and 
Osmek, 1998; Bain and Williams, 2006). This apparent difference in 
responsiveness of these two porpoise species is consistent with their 
relative responsiveness to boat traffic and some other acoustic sources 
(Richardson et al., 1995; Southall et al., 2007).
    Most studies of sperm whales exposed to airgun sounds indicate that 
the sperm whale shows considerable tolerance of airgun pulses (e.g., 
Stone, 2003; Moulton et al., 2005, 2006a; Stone and Tasker, 2006; Weir, 
2008). In most cases the whales do not show strong avoidance, and they 
continue to call (see Appendix A of SIO's EA for review). However, 
controlled exposure experiments in the GOM indicate that foraging 
behavior was altered upon exposure to airgun sound (Jochens et al., 
2008; Miller et al., 2009; Tyack, 2009).
    There are almost no specific data on the behavioral reactions of 
beaked whales to seismic surveys. However, some northern bottlenose 
whales (Hyperoodon ampullatus) remained in the general area and 
continued to produce high-frequency clicks when exposed to sound pulses 
from distant seismic surveys (Gosselin and Lawson, 2004; Laurinolli and 
Cochrane, 2005; Simard et al., 2005). Most beaked whales tend to avoid 
approaching vessels of other types (e.g., Wursig et al., 1998). They 
may also dive for an extended period when approached by a vessel (e.g., 
Kasuya, 1986), although it is uncertain how much longer such dives may 
be as compared to dives by undisturbed beaked whales, which also are 
often quite long (Baird et al., 2006; Tyack et al., 2006). Based on a 
single observation, Aguilar-Soto et al. (2006) suggested that foraging 
efficiency of Cuvier's beaked whales may be reduced by close approach 
of vessels. In any event, it is likely that most beaked whales would 
also show strong avoidance of an approaching seismic vessel, although 
this has not been documented explicitly. In fact, Moulton and Holst 
(2010) reported 15 sightings of beaked whales during seismic studies in 
the Northwest Atlantic; seven of those sightings were made at times 
when at least one airgun was operating. There was little evidence to 
indicate that beaked whale behavior was affected by airgun operations; 
sighting rates and distances were similar during seismic and non-
seismic periods (Moulton and Holst, 2010).
    There are increasing indications that some beaked whales tend to 
strand when naval exercises involving mid-frequency sonar operation are 
ongoing nearby (e.g., Simmonds and Lopez-Jurado, 1991; Frantzis, 1998; 
NOAA and USN, 2001; Jepson et al., 2003; Hildebrand, 2005; Barlow and 
Gisiner, 2006; see also the Stranding and Mortality section in this 
notice). These strandings are apparently a disturbance response, 
although auditory or other injuries or other physiological effects may 
also be involved. Whether beaked whales would ever react similarly to 
seismic surveys is unknown. Seismic survey sounds are quite different 
from those of the sonar in operation during the above-cited incidents.
    Odontocete reactions to large arrays of airguns are variable and, 
at least for delphinids and Dall's porpoises, seem to be confined to a 
smaller radius than has been observed for the more responsive of the 
mysticetes, belugas, and harbor porpoises (Appendix A of SIO'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 A(5) of SIO's 
EA. In the Beaufort Sea, some ringed seals avoided an area of 100 m to 
(at most) a few hundred meters around seismic vessels, but many seals 
remained within 100 to 200 m (328 to 656 ft) of the trackline as the 
operating airgun array passed by (e.g., Harris et al., 2001; Moulton 
and Lawson, 2002; Miller et al., 2005). Ringed seal sightings averaged 
somewhat farther away from the seismic vessel when the airguns were 
operating than when they were not, but the difference was small 
(Moulton and Lawson, 2002). Similarly, in Puget Sound, sighting 
distances for harbor seals and California sea lions tended to be larger 
when airguns were operating (Calambokidis and Osmek, 1998). Previous 
telemetry work suggests that avoidance and other behavioral reactions 
may be stronger than evident to date from visual studies (Thompson et 
al., 1998).

Hearing Impairment and Other Physical Effects

    Exposure to high intensity sound for a sufficient duration may 
result in auditory effects such as a noise-induced threshold shift--an 
increase in the auditory threshold after exposure to noise (Finneran, 
Carder, Schlundt, and Ridgway, 2005). Factors that influence the amount 
of threshold shift include the amplitude, duration, frequency content, 
temporal pattern, and energy distribution of noise exposure. The 
magnitude of hearing threshold shift normally decreases over time 
following cessation of the noise exposure. The amount of threshold 
shift just after exposure is called the initial threshold shift. If the 
threshold shift eventually returns to zero (i.e., the threshold returns 
to the pre-exposure value), it is called temporary threshold shift 
(TTS) (Southall et al., 2007).
    Researchers have studied TTS in certain captive odontocetes and 
pinnipeds exposed to strong sounds (reviewed in Southall et al., 2007). 
However, there has been no specific documentation of TTS let alone 
permanent hearing damage, i.e., permanent threshold shift (PTS), in 
free-ranging marine mammals exposed to sequences of airgun pulses 
during realistic field conditions.
    Temporary Threshold Shift--TTS is the mildest form of hearing 
impairment that can occur during exposure to a strong sound (Kryter, 
1985). While experiencing TTS, the hearing threshold rises and a sound 
must be stronger in order to be heard. At least in terrestrial mammals, 
TTS can last from minutes or

[[Page 45529]]

hours to (in cases of strong TTS) days. For sound exposures at or 
somewhat above the TTS threshold, hearing sensitivity in both 
terrestrial and marine mammals recovers rapidly after exposure to the 
noise ends. Few data on sound levels and durations necessary to elicit 
mild TTS have been obtained for marine mammals, and none of the 
published data concern TTS elicited by exposure to multiple pulses of 
sound. Available data on TTS in marine mammals are summarized in 
Southall et al. (2007). Table 1 (above) presents the distances from the 
Thompson's airguns at which the received energy level (per pulse, flat-
weighted) would be expected to be greater than or equal to 190 dB re 1 
[mu]Pa (rms).
    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, SIO expects no cases of TTS given the low abundance of 
baleen whales in the proposed survey area at the time of the proposed 
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 (non-pulse) exposures suggested 
that some pinnipeds (harbor seals in particular) incur TTS at somewhat 
lower received levels than do small odontocetes exposed for similar 
durations (Kastak et al., 1999, 2005; Ketten et al., 2001). The TTS 
threshold for pulsed sounds has been indirectly estimated as being an 
SEL of approximately 171 dB re 1 [micro]Pa\2\[middot]s (Southall et 
al., 2007) which would be equivalent to a single pulse with a received 
level of approximately 181 to 186 dB re 1 [micro]Pa (rms), or a series 
of pulses for which the highest rms values are a few dB lower. 
Corresponding values for California sea lions and northern elephant 
seals are likely to be higher (Kastak et al., 2005).
    To avoid the potential for injury, NMFS (1995, 2000) concluded that 
cetaceans should not be exposed to pulsed underwater noise at received 
levels exceeding 180 dB re 1 [mu]Pa (rms) and pinnipeds should not be 
exposed to pulsed underwater noise at received levels exceeding 190 dB 
re 1 [mu]Pa (rms). NMFS believes that to avoid the potential for 
permanent physiological damage (Level A harassment), cetaceans should 
not be exposed to pulsed underwater noise at received levels exceeding 
180 dB re 1 [mu]Pa (rms) and pinnipeds should not be exposed to pulsed 
underwater noise at received levels exceeding 190 dB re 1 [mu]Pa (rms). 
The 180 dB and 190 dB levels are the shutdown criterion applicable to 
cetaceans and pinnipeds, respectively, as specified by NMFS (2000); 
these levels were used to establish the EZs. NMFS also assumes that 
marine mammals exposed to levels exceeding 160 dB re 1 [mu]Pa (rms) may 
experience Level B harassment.
    Permanent Threshold Shift--When PTS occurs, there is physical 
damage to the sound receptors in the ear. In severe cases, there can be 
total or partial deafness, whereas in other cases, the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985). There is no specific evidence that exposure to pulses of airgun 
sound can cause PTS in any marine mammal, even with large arrays of 
airguns. However, given the possibility that mammals close to an airgun 
array might incur at least mild TTS, there has been further speculation 
about the possibility that some individuals occurring very close to 
airguns might incur PTS (e.g., Richardson et al., 1995, p. 372ff; 
Gedamke et al., 2008). Single or occasional occurrences of mild TTS are 
not indicative of permanent auditory damage, but repeated or (in some 
cases) single exposures to a level well above that causing TTS onset 
might elicit PTS.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, but are assumed to be similar to those in humans and 
other terrestrial mammals. PTS might occur at a received sound level at 
least several dBs above that inducing mild TTS if the animal were 
exposed to strong sound pulses with rapid rise time--see Appendix A (6) 
of SIO'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--Marine mammals close to underwater 
detonations of high explosives can be killed or severely injured, and 
the auditory organs are especially susceptible to injury (Ketten et 
al., 1993; Ketten, 1995). However, explosives are no longer used for 
marine waters for commercial seismic surveys or (with rare exceptions) 
for seismic research; they have been replaced entirely by airguns or 
related non-explosive pulse generators. Airgun pulses are less 
energetic and have slower rise times, and there is no specific evidence 
that they can cause serious injury, death, or stranding even in the 
case of large airgun arrays. However, the association of strandings of 
beaked whales with naval exercises involving mid-frequency active sonar 
and, in one case, an L-DEO seismic survey (Malakoff, 2002; Cox et al., 
2006), has raised the possibility that beaked whales exposed to strong 
``pulsed'' sounds may be especially susceptible to injury and/or 
behavioral reactions that can lead to stranding (e.g., Hildebrand, 
2005; Southall et al., 2007). Appendix A (6) of SIO'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

[[Page 45530]]

    (4) Tissue damage directly from sound exposure, such as through 
acoustically-mediated bubble formation and growth or acoustic resonance 
of tissues. Some of these mechanisms are unlikely to apply in the case 
of impulse sounds. However, there are indications that gas-bubble 
disease (analogous to ``the bends''), induced in supersaturated tissue 
by a behavioral response to acoustic exposure, could be a pathologic 
mechanism for the strandings and mortality of some deep-diving 
cetaceans exposed to sonar. However, the evidence for this remains 
circumstantial and associated with exposure to naval mid-frequency 
sonar, not seismic surveys (Cox et al., 2006; Southall et al., 2007).
    Seismic pulses and mid-frequency sonar signals are quite different, 
and some mechanisms by which sonar sounds have been hypothesized to 
affect beaked whales are unlikely to apply to airgun pulses. Sounds 
produced by airgun arrays are broadband impulses with most of the 
energy below one kHz. Typical military mid-frequency sonar emits non-
impulse sounds at frequencies of two to 10 kHz, generally with a 
relatively narrow bandwidth at any one time. A further difference 
between seismic surveys and naval exercises is that naval exercises can 
involve sound sources on more than one vessel. Thus, it is not 
appropriate to assume that there is a direct connection between the 
effects of military sonar and seismic surveys on marine mammals. 
However, evidence that sonar signals can, in special circumstances, 
lead (at least indirectly) to physical damage and mortality (e.g., 
Balcomb and Claridge, 2001; NOAA and USN, 2001; Jepson et al., 2003; 
Fern[aacute]ndez et al., 2004, 2005; Hildebrand 2005; Cox et al., 2006) 
suggests that caution is warranted when dealing with exposure of marine 
mammals to any high-intensity ``pulsed'' sound.
    There is no conclusive evidence of cetacean strandings or deaths at 
sea as a result of exposure to seismic surveys, but a few cases of 
strandings in the general area where a seismic survey was ongoing have 
led to speculation concerning a possible link between seismic surveys 
and strandings. Suggestions that there was a link between seismic 
surveys and strandings of humpback whales in Brazil (Engel et al., 
2004) were not well founded (IAGC, 2004; IWC, 2007). In September 2002, 
there was a stranding of two Cuvier's beaked whales (Ziphius 
cavirostris) in the Gulf of California, Mexico, when the L-DEO vessel 
R/V Maurice Ewing was operating a 20 airgun (8,490 in\3\) array in the 
general area. The link between the stranding and the seismic surveys 
was inconclusive and not based on any physical evidence (Hogarth, 2002; 
Yoder, 2002). Nonetheless, the Gulf of California incident plus the 
beaked whale strandings near naval exercises involving use of mid-
frequency sonar suggests a need for caution in conducting seismic 
surveys in areas occupied by beaked whales until more is known about 
effects of seismic surveys on those species (Hildebrand, 2005). No 
injuries of beaked whales are anticipated during the proposed study 
because of:
    (1) The high likelihood that any beaked whales nearby would avoid 
the approaching vessel before being exposed to high sound levels, and
    (2) Differences between the sound sources operated by SIO and those 
involved in the naval exercises associated with strandings.
    Non-auditory Physiological Effects--Non-auditory physiological 
effects or injuries that theoretically might occur in marine mammals 
exposed to strong underwater sound include stress, neurological 
effects, bubble formation, resonance, and other types of organ or 
tissue damage (Cox et al., 2006; Southall et al., 2007). Studies 
examining such effects are limited. However, resonance effects (Gentry, 
2002) and direct noise-induced bubble formations (Crum et al., 2005) 
are implausible in the case of exposure to an impulsive broadband 
source like an airgun array. If seismic surveys disrupt diving patterns 
of deep-diving species, this might perhaps result in bubble formation 
and a form of the bends, as speculated to occur in beaked whales 
exposed to sonar. However, there is no specific evidence of this upon 
exposure to airgun pulses.
    In general, very little is known about the potential for seismic 
survey sounds (or other types of strong underwater sounds) to cause 
non-auditory physical effects in marine mammals. Such effects, if they 
occur at all, would presumably be limited to short distances and to 
activities that extend over a prolonged period. The available data do 
not allow identification of a specific exposure level above which non-
auditory effects can be expected (Southall et al., 2007), or any 
meaningful quantitative predictions of the numbers (if any) of marine 
mammals that might be affected in those ways. Marine mammals that show 
behavioral avoidance of seismic vessels, including most baleen whales 
and some odontocetes, are especially unlikely to incur non-auditory 
physical effects.

Potential Effects of Other Acoustic Devices

MBES
    SIO will operate the Kongsberg EM 300 MBES from the source vessel 
during the planned study. Sounds from the MBES are very short pulses, 
occurring for five 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 30 kHz, and the maximum source level is 237 dB re 1 
[mu]Pa (rms). The beam is narrow (1[deg]) in fore-aft extent and wide 
(36[deg]) in the cross-track extent. Each ping consists of nine (in 
water greater than 1,000 m deep) or three (in water less than 1,000 m 
deep) successive fan-shaped transmissions (segments) at different 
cross-track angles. Any given mammal at depth near the trackline would 
be in the main beam for only one or two of the nine segments. Also, 
marine mammals that encounter the Kongsberg EM 300 are unlikely to be 
subjected to repeated pulses because of the narrow fore-aft width of 
the beam and will receive only limited amounts of pulse energy because 
of the short pulses. Animals close to the ship (where the beam is 
narrowest) are especially unlikely to be ensonified for more than one 
five ms pulse (or two pings 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 300; 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 SIO's operations, the individual pulses will be 
very short, and a given mammal would not receive many of the downward-
directed pulses as the vessel passes by. Possible effects of an MBES on 
marine mammals are outlined below.
    Masking--Marine mammal communications will not be masked 
appreciably by the MBES signals given the low duty cycle of the 
echosounder and the brief period when an individual mammal is likely to 
be within its beam. Furthermore, in the case of baleen

[[Page 45531]]

whales, the MBES signals (12 kHz) do not overlap with the predominant 
frequencies in the calls, which would avoid any significant masking.
    Behavioral Responses--Behavioral reactions of free-ranging marine 
mammals to sonars, echosounders, and other sound sources appear to vary 
by species and circumstance. Observed reactions have included silencing 
and dispersal by sperm whales (Watkins et al., 1985), increased 
vocalizations and no dispersal by pilot whales (Globicephala melas) 
(Rendell and Gordon, 1999), and the previously-mentioned beachings by 
beaked whales. During exposure to a 21 to 25 kHz ``whale-finding'' 
sonar with a source level of 215 dB re 1 [micro]Pa, gray whales reacted 
by orienting slightly away from the source and being deflected from 
their course by approximately 200 m (Frankel, 2005). When a 38 kHz 
echosounder and a 150 kHz acoustic Doppler current profiler were 
transmitting during studies in the Eastern Tropical Pacific, baleen 
whales showed no significant responses, while spotted and spinner 
dolphins were detected slightly more often and beaked whales less often 
during visual surveys (Gerrodette and Pettis, 2005).
    Captive bottlenose dolphins and a beluga whale exhibited changes in 
behavior when exposed to 1 s tonal signals at frequencies similar to 
those that will be emitted by the MBES used by SIO, and to shorter 
broadband pulsed signals. Behavioral changes typically involved what 
appeared to be deliberate attempts to avoid the sound exposure 
(Schlundt et al., 2000; Finneran et al., 2002; Finneran and Schlundt, 
2004). The relevance of those data to free-ranging odontocetes is 
uncertain, and in any case, the test sounds were quite different in 
duration as compared with those from an MBES.
    Very few data are available on the reactions of pinnipeds to 
echosounder sounds at frequencies similar to those used during seismic 
operations. Hastie and Janik (2007) conducted a series of behavioral 
response tests on two captive gray seals to determine their reactions 
to underwater operation of a 375 kHz multibeam imaging echosounder that 
included significant signal components down to 6 kHz. Results indicated 
that the two seals reacted to the signal by significantly increasing 
their dive durations. Because of the likely brevity of exposure to the 
MBES sounds, pinniped reactions are expected to be limited to startle 
or otherwise brief responses of no lasting consequences to the animals.
    Hearing Impairment and Other Physical Effects--Given recent 
stranding events that have been associated with the operation of naval 
sonar, there is concern that mid-frequency sonar sounds can cause 
serious impacts to marine mammals (see above). However, the MBES 
proposed for use by SIO is quite different than sonar used for Navy 
operations. Pulse duration of the MBES is very short relative to the 
naval sonar. Also, at any given location, an individual marine mammal 
would be in the beam of the MBES for much less time given the generally 
downward orientation of the beam and its narrow fore-aft beamwidth; 
Navy sonar often uses near-horizontally-directed sound. Those factors 
would all reduce the sound energy received from the MBES rather 
drastically relative to that from naval sonar.
    NMFS believes that the brief exposure of marine mammals to one 
pulse, or small numbers of signals, from the MBES is not likely to 
result in the harassment of marine mammals.
SBP
    SIO will also operate a SBP from the source vessel during the 
proposed survey. Sounds from the SBP are very short pulses, occurring 
for up to 25 ms once every three to eight s. Most of the energy in the 
sound pulses emitted by the SBP is at three to six kHz, and the beam is 
directed downward. The SBP on the Thompson has a maximum source level 
of 211 dB re 1 [mu]Pa (rms).
    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 
Thompson--if the animal was in the area, it would have to pass the 
transducer at close range in order to be subjected to sound levels that 
could cause TTS.
    Masking--Marine mammal communications will not be masked 
appreciably by the SBP signals given the directionality of the signal 
and the brief period when an individual mammal is likely to be within 
its beam. Furthermore, in the case of most baleen whales, the SBP 
signals do not overlap with the predominant frequencies in the calls, 
which would avoid significant masking.
    Behavioral Responses--Marine mammal behavioral reactions to other 
pulsed sound sources are discussed above, and responses to the SBP are 
likely to be similar to those for other pulsed sources if received at 
the same levels. However, the pulsed signals from the SBP are 
considerably weaker than those from the MBES. Therefore, behavioral 
responses are not expected unless marine mammals are very close to the 
source.
    Hearing Impairment and Other Physical Effects--It is unlikely that 
the SBP produces pulse levels strong enough to cause hearing impairment 
or other physical injuries even in an animal that is (briefly) in a 
position near the source. The SBP is usually operated simultaneously 
with other higher-power acoustic sources, including airguns. Many 
marine mammals will move away in response to the approaching higher-
power sources or the vessel itself before the mammals would be close 
enough for there to be any possibility of effects from the less intense 
sounds from the SBP.
    The potential effects to marine mammals described in this section 
of the document do not take into consideration the proposed monitoring 
and mitigation measures described later in this document (see the 
``Proposed Mitigation'' and ``Proposed Monitoring and Reporting'' 
sections) which, as noted are designed to effect the least practicable 
adverse impact on affected marine mammal species and stocks.

Anticipated Effects on Marine Mammal Habitat

    The proposed seismic survey will not result in any permanent impact 
on habitats used by the marine mammals in the proposed survey area, 
including the food sources they use (i.e. fish and invertebrates), and 
there will be no physical damage to any habitat. While it is 
anticipated that the specified activity may result in marine mammals 
avoiding certain areas due to temporary ensonification, this impact to 
habitat is temporary and reversible and was considered in further 
detail earlier in this document, as behavioral modification. The main 
impact associated with the proposed activity will be temporarily 
elevated noise levels and the associated direct effects on marine 
mammals, previously discussed in this notice.

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 C of SIO'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

[[Page 45532]]

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. This makes drawing conclusions about impacts on fish problematic 
because ultimately, the most important aspect of potential impacts 
relates to how exposure to seismic survey sound affects marine fish 
populations and their viability, including their availability to 
fisheries.
    Hastings and Popper (2005), Popper (2009), and Popper and Hastings 
(2009a,b) provided recent critical reviews of the known effects of 
sound on fish. The following sections provide a general synopsis of the 
available information on the effects of exposure to seismic and other 
anthropogenic sound as relevant to fish. The information comprises 
results from scientific studies of varying degrees of rigor plus some 
anecdotal information. Some of the data sources may have serious 
shortcomings in methods, analysis, interpretation, and reproducibility 
that must be considered when interpreting their results (see Hastings 
and Popper, 2005). Potential adverse effects of the program's sound 
sources on marine fish are noted.
    Pathological Effects--The potential for pathological damage to 
hearing structures in fish depends on the energy level of the received 
sound and the physiology and hearing capability of the species in 
question (see Appendix C of SIO'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 SIO and NMFS know, there are only two papers with proper 
experimental methods, controls, and careful pathological investigation 
implicating sounds produced by actual seismic survey airguns in causing 
adverse anatomical effects. One such study indicated anatomical damage, 
and the second indicated TTS in fish hearing. The anatomical case is 
McCauley et al. (2003), who found that exposure to airgun sound caused 
observable anatomical damage to the auditory maculae of pink snapper 
(Pagrus auratus). This damage in the ears had not been repaired in fish 
sacrificed and examined almost two months after exposure. On the other 
hand, Popper et al. (2005) documented only TTS (as determined by 
auditory brainstem response) in two of three fish species from the 
Mackenzie River Delta. This study found that broad whitefish (Coregonus 
nasus) exposed to five airgun shots were not significantly different 
from those of controls. During both studies, the repetitive exposure to 
sound was greater than would have occurred during a typical seismic 
survey. However, the substantial low-frequency energy produced by the 
airguns [less than 400 Hz in the study by McCauley et al. (2003) and 
less than approximately 200 Hz in Popper et al. (2005)] likely did not 
propagate to the fish because the water in the study areas was very 
shallow (approximately nine m in the former case and less than two m in 
the latter). Water depth sets a lower limit on the lowest sound 
frequency that will propagate (the ``cutoff frequency'') at about one-
quarter wavelength (Urick, 1983; Rogers and Cox, 1988).
    Wardle et al. (2001) suggested that in water, acute injury and 
death of organisms exposed to seismic energy depends primarily on two 
features of the sound source: (1) The received peak pressure and (2) 
the time required for the pressure to rise and decay. Generally, as 
received pressure increases, the period for the pressure to rise and 
decay decreases, and the chance of acute pathological effects 
increases. According to Buchanan et al. (2004), for the types of 
seismic airguns and arrays involved with the proposed program, the 
pathological (mortality) zone for fish would be expected to be within a 
few meters of the seismic source. Numerous other studies provide 
examples of no fish mortality upon exposure to seismic sources (Falk 
and Lawrence, 1973; Holliday et al., 1987; La Bella et al., 1996; 
Santulli et al., 1999; McCauley et al., 2000a,b, 2003; Bjarti, 2002; 
Thomsen, 2002; Hassel et al., 2003; Popper et al., 2005; Boeger et al., 
2006).
    Some studies have reported, some equivocally, that mortality of 
fish, fish eggs, or larvae can occur close to seismic sources 
(Kostyuchenko, 1973; Dalen and Knutsen, 1986; Booman et al., 1996; 
Dalen et al., 1996). Some of the reports claimed seismic effects from 
treatments quite different from actual seismic survey sounds or even 
reasonable surrogates. However, Payne et al. (2009) reported no 
statistical differences in mortality/morbidity between control and 
exposed groups of capelin eggs or monkfish larvae. Saetre and Ona 
(1996) applied a `worst-case scenario' mathematical model to 
investigate the effects of seismic energy on fish eggs and larvae. They 
concluded that mortality rates caused by exposure to seismic surveys 
are so low, as compared to natural mortality rates, that the impact of 
seismic surveying on recruitment to a fish stock must be regarded as 
insignificant.
    Physiological Effects--Physiological effects refer to cellular and/
or biochemical responses of fish to acoustic stress. Such stress 
potentially could affect fish populations by increasing mortality or 
reducing reproductive success. Primary and secondary stress responses 
of fish after exposure to seismic survey sound appear to be temporary 
in all studies done to date (Sverdrup et al., 1994; Santulli et al., 
1999; McCauley et al., 2000a,b). The periods necessary for the 
biochemical changes to return to normal are variable and depend on 
numerous aspects of the biology of the species and of the sound 
stimulus (see Appendix C of SIO's EA).
    Behavioral Effects--Behavioral effects include changes in the 
distribution, migration, mating, and catchability of fish populations. 
Studies investigating the possible effects of sound (including seismic 
survey sound) on fish behavior have been conducted on both uncaged and 
caged individuals (e.g., Chapman and Hawkins, 1969; Pearson et al., 
1992; Santulli et al., 1999; Wardle et al., 2001; Hassel et al., 2003). 
Typically, in these studies fish exhibited a sharp ``startle'' response 
at the onset of a sound

[[Page 45533]]

followed by habituation and a return to normal behavior after the sound 
ceased.
    There is general concern about potential adverse effects of seismic 
operations on fisheries, namely a potential reduction in the 
``catchability'' of fish involved in fisheries. Although reduced catch 
rates have founded by other sources of disturbance (Dalen and Raknes, 
1985; Dalen and Knutsen, 1986; Lokkeborg, 1991; Skalski et al., 1992; 
Engas et al., 1996). In other airgun experiments, there was no change 
in catch per unit effort of fish when airgun pulses were emitted, 
particularly in the immediate vicinity of the seismic survey (Pickett 
et al., 1994; La Bella et al., 1996). For some species, reductions in 
catch may have resulted from a change in behavior of the fish, e.g., a 
change in vertical or horizontal distribution, as reported in Slotte et 
al. (2004).
    In general, any adverse effects on fish behavior or fisheries 
attributable to seismic testing may depend on the species in question 
and the nature of the fishery (season, duration, fishing method). They 
may also depend on the age of the fish, its motivational state, its 
size, and numerous other factors that are difficult, if not impossible, 
to quantify at this point, given such limited data on effects of 
airguns on fish, particularly under realistic at-sea conditions.

Anticipated Effects on Invertebrates

    The existing body of information on the impacts of seismic survey 
sound on marine invertebrates is very limited. However, there is some 
unpublished and very limited evidence of the potential for adverse 
effects on invertebrates, thereby justifying further discussion and 
analysis of this issue. The three types of potential effects of 
exposure to seismic surveys on marine invertebrates are pathological, 
physiological, and behavioral. Based on the physical structure of their 
sensory organs, marine invertebrates appear to be specialized to 
respond to particle displacement components of an impinging sound field 
and not to the pressure component (Popper et al., 2001; see also 
Appendix D of SIO's EA).
    The only information available on the impacts of seismic surveys on 
marine invertebrates involves studies of individuals; there have been 
no studies at the population scale. Thus, available information 
provides limited insight on possible real-world effects at the regional 
or ocean scale. The most important aspect of potential impacts concerns 
how exposure to seismic survey sound ultimately affects invertebrate 
populations and their viability, including availability to fisheries.
    Literature reviews of the effects of seismic and other underwater 
sound on invertebrates were provided by Moriyasu et al. (2004) and 
Payne et al. (2008). The following sections provide a synopsis of 
available information on the effects of exposure to seismic survey 
sound on species of decapod crustaceans and cephalopods, the two 
taxonomic groups of invertebrates on which most such studies have been 
conducted. The available information is from studies with variable 
degrees of scientific soundness and from anecdotal information. A more 
detailed review of the literature on the effects of seismic survey 
sound on invertebrates is provided in Appendix D of SIO's EA.
    Pathological Effects--In water, lethal and sub-lethal injury to 
organisms exposed to seismic survey sound appears to depend on at least 
two features of the sound source: (1) The received peak pressure; and 
(2) the time required for the pressure to rise and decay. Generally, as 
received pressure increases, the period for the pressure to rise and 
decay decreases, and the chance of acute pathological effects 
increases. For the type of airgun array planned for the proposed 
program, the pathological (mortality) zone for crustaceans and 
cephalopods is expected to be within a few meters of the seismic 
source, at most; however, very few specific data are available on 
levels of seismic signals that might damage these animals. This premise 
is based on the peak pressure and rise/decay time characteristics of 
seismic airgun arrays currently in use around the world.
    Some studies have suggested that seismic survey sound has a limited 
pathological impact on early developmental stages of crustaceans 
(Pearson et al., 1994; Christian et al., 2003; DFO, 2004). However, the 
impacts appear to be either temporary or insignificant compared to what 
occurs under natural conditions. Controlled field experiments on adult 
crustaceans (Christian et al., 2003, 2004; DFO, 2004) and adult 
cephalopods (McCauley et al., 2000a,b) exposed to seismic survey sound 
have not resulted in any significant pathological impacts on the 
animals. It has been suggested that exposure to commercial seismic 
survey activities has injured giant squid (Guerra et al., 2004), but 
the article provides little evidence to support this claim. Recent work 
by Andre et al. (2011) purports to present the first morphological and 
ultrastructural evidence of massive acoustic trauma (i.e., permanent 
and substantial alterations of statocyst sensory hair cells) in four 
cephalopod species subjected to low-frequency sound. The cephalopods, 
primarily cuttlefish, were exposed to continuous 50 to 400 Hz 
sinusoidal wave sweeps (100% duty cycle and 1 s sweep period) for two 
hours while captive in relatively small tanks (one 2,000 liter [L, 
2m\3\] and one 200 L [0.2 m\3\] tank), and reported morphological and 
ultrastructural evidence of massive acoustic trauma (i.e., permanent 
and substantial alterations of statocyst sensory hair cells). The 
received SPL was reported as 1575 dB re 1 [micro]Pa, with 
peak levels at 175 dB re 1 [micro]Pa. As in the McCauley et al. (2003) 
paper on sensory hair cell damage in pink snapper as a result of 
exposure to seismic sound, the cephalopods were subjected to higher 
sound levels than they would be under natural conditions, and they were 
unable to swim away from the sound source.
    Physiological Effects--Physiological effects refer mainly to 
biochemical responses by marine invertebrates to acoustic stress. Such 
stress potentially could affect invertebrate populations by increasing 
mortality or reducing reproductive success. Primary and secondary 
stress responses (i.e., changes in haemolymph levels of enzymes, 
proteins, etc.) of crustaceans have been noted several days or months 
after exposure to seismic survey sounds (Payne et al., 2007). 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

[[Page 45534]]

(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.
    SIO has based the mitigation measures described herein, to be 
implemented for the proposed seismic survey, on the following:
    (1) Protocols used during previous SIO 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, SIO and/or its designees has proposed 
to implement the following mitigation measures for marine mammals:
    (1) Proposed exclusion zones;
    (2) Speed or course alteration;
    (3) Shut-down procedures; and
    (4) Ramp-up procedures.
    Proposed Exclusion Zones--Received sound levels have been modeled 
by L-DEO for a number of airgun configurations, including two 105 in\3\ 
GI airguns, in relation to distance and direction from the airguns (see 
Figure 2 of the IHA application). The model does not allow for bottom 
interactions, and is most directly applicable to deep water. Based on 
the modeling, estimates of the maximum distances from the source where 
sound levels are predicted to be 190, 180, and 160 dB re 1 [mu]Pa (rms) 
in deep water were determined (see Table 1 above).
    Empirical data concerning the 190, 180, and 160 dB (rms) distances 
were acquired for various airgun arrays based on measurements during 
the acoustic verification studies conducted by L-DEO in the northern 
GOM in 2003 (Tolstoy et al., 2004) and 2007 to 2008 (Tolstoy et al., 
2009). Results of the 36 airgun array are not relevant for the two GI 
airguns to be used in the proposed survey. The empirical data for the 
6, 10, 12, and 20 airgun arrays indicate that, for deep water, the L-
DEO model tends to overestimate the received sound levels at a given 
distance (Tolstoy et al., 2004). Measurements were not made for the two 
GI airgun array in deep water, however, SIO proposes to use the EZ 
predicted by L-DEO's model for the proposed GI airgun operations in 
deep water, although they are likely conservative give the empirical 
results for the other arrays.
    The 180 and 190 dB radii are shut-down criteria applicable to 
cetaceans and pinnipeds, respectively, as specified by NMFS (2000); 
these levels were used to establish the EZs. If the PSO detects marine 
mammal(s) within or about to enter the appropriate EZ, the airguns will 
be shut-down, immediately.
    Speed or Course Alteration--If a marine mammal is detected outside 
the EZ an, based on its position and the relative motion, is likely to 
enter the EZ, the vessel's speed and/or direct course could be changed. 
This would be done if operationally practicable while minimizing the 
effect on the planned science objectives. The activities and movements 
of the marine mammal (relative to the seismic vessel) will then be 
closely monitored to determine whether the animal is approaching the 
applicable EZ. If the animal appears likely to enter the EZ, further 
mitigative actions will be taken, i.e., either further course 
alterations or a shut-down of the seismic source. Typically, during 
seismic operations, the source vessel is unable to change speed or 
course and one or more alternative mitigation measures will need to be 
implemented.
    Shut-down Procedures--SIO will shut down the operating airgun(s) if 
a marine mammal is seen outside the EZ for the airgun(s), and if the 
vessel's speed and/or course cannot be changed to avoid having the 
animal enter the EZ, the seismic source will be shut-down before the 
animal is within the EZ. If a marine mammal is already within the EZ 
when first detected, the seismic source will be shut-down immediately.
    Following a shut-down, SIO will not resume airgun activity until 
the marine mammal has cleared the EZ. SIO will consider the animal to 
have cleared the EZ if:
     A PSO has visually observed the animal leave the EZ, or
     A PSO has not sighted the animal within the EZ for 15 min 
for species with shorter dive durations (i.e., small odontocetes or 
pinnipeds), or 30 min for species with longer dive durations (i.e., 
mysticetes and large odontocetes, including sperm, killer, and beaked 
whales).
    Ramp-up Procedures--SIO will follow a ramp-up procedure when the 
airgun array begins operating after a specified period without airgun 
operations or when a shut-down has exceeded that period. SIO proposes 
that, for the present cruise, this period would be approximately 15 
min. SIO has used similar periods (approximately 15 min) during 
previous SIO surveys.
    Ramp-up will begin with a single GI airgun (105 in\3\). The second 
GI airgun (105 in\3\) will be added after five min. During ramp-up, the 
Protected Species Observers (PSOs) will monitor the EZ, and if marine 
mammals are sighted, SIO will implement a shut-down as though both GI 
airguns were operational.
    If the complete EZ has not been visible for at least 30 min prior 
to the start of operations in either daylight or nighttime, SIO will 
not commence the ramp-up. If one airgun has operated, ramp-up to full 
power will be permissible at night or in poor visibility, on the 
assumption that marine mammals will be alerted to the approaching 
seismic vessel by the sounds from the single airgun and could move away 
if they choose. A ramp-up from a shut-down may occur at night, but only 
where the EZ is small enough to be visible. SIO 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 prescribes the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. NMFS's evaluation of potential measures 
included consideration of the following factors in relation to one 
another:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure is expected to minimize adverse impacts 
to marine mammals;
    (2) The proven or likely efficacy of the specific measure to 
minimize adverse impacts as planned; and
    (3) The practicability of the measure for applicant implementation.
    Based on NMFS's evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS or recommended by the public, 
NMFS has preliminarily determined that the proposed mitigation measures 
provide the means of effecting the least practicable adverse impacts on 
marine

[[Page 45535]]

mammal species or stocks and their habitat, paying particular attention 
to rookeries, mating grounds, and areas of similar significance.

Proposed Monitoring and Reporting

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

Monitoring

    SIO proposes to sponsor marine mammal monitoring during the 
proposed project, in order to implement the proposed mitigation 
measures that require real-time monitoring, and to satisfy the 
anticipated monitoring requirements of the IHA. SIO's proposed 
Monitoring Plan is described below this section. SIO 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. SIO 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

    PSOs will be based aboard the seismic source vessel and will watch 
for marine mammals near the vessel during daytime airgun operations and 
during any ramp-ups at night. PSOs will also watch for marine mammals 
near the seismic vessel for at least 30 min prior to the ramp-up of 
airgun operations after an extended shut-down (i.e., greater than 
approximately 15 min for this proposed cruise). When feasible, PSOs 
will conduct observations during daytime periods when the seismic 
system is not operating for comparison of sighting rates and behavior 
with and without airgun operations and between acquisition periods. 
Based on PSO observations, the airguns will be shut-down when marine 
mammals are observed within or about to enter a designated EZ. The EZ 
is a region in which a possibility exists of adverse effects on animal 
hearing or other physical effects.
    During seismic operations in the western tropical Pacific Ocean, at 
least three PSOs will be based aboard the Thompson. SIO will appoint 
the PSOs with NMFS's concurrence. At least one PSO will monitor the EZs 
during seismic operations. Observations will take place during ongoing 
daytime operations and nighttime ramp-ups of the airguns. PSO(s) will 
be on duty in shifts of duration no longer than 4 hr. The vessel crew 
will also be instructed to assist in detecting marine mammals.
    The Thompson is a suitable platform for marine mammal observations. 
Two locations are likely as observation stations onboard the Thompson. 
At one station on the bridge, the eye level will be approximately 13.8 
m (45.3 ft) above sea level and the location will give the PSO a good 
view around the entire vessel (i.e., 310[deg] for one PSO and a full 
360[deg] when two PSOs are stationed at different vantage points). A 
second observation site is the 03 deck where the PSOs eye level will be 
10.8 m (35.4 ft) above sea level. The 03 deck offers a view of 330[deg] 
for the two PSOs.
    During daytime, the PSVOs will scan the area around the vessel 
systematically with reticle binoculars (e.g., 7 x 50 Fujinon), Big-eye 
binoculars (25 x 150), optical range finders and with the naked eye. 
During darkness, night vision devices (NVDs) will be available, when 
required. The PSOs will be in wireless communication with the vessel's 
officers on the bridge and scientists in the vessel's operations 
laboratory, so they can advise promptly of the need for avoidance 
maneuvers or seismic source shut-down. When marine mammals are detected 
within or about to enter the designated EZ, the airguns will 
immediately be shut-down if necessary. The PSO(s) will continue to 
maintain watch to determine when the animal(s) are outside the EZ by 
visual confirmation. Airgun operations will not resume until the animal 
is confirmed to have left the EZ, or if not observed after 15 min for 
species with shorter dive durations (small odontocetes and pinnipeds) 
or 30 min for species with longer dive durations (mysticetes and large 
odontocetes, including sperm, killer, and beaked whales).

PSO Data and Documentation

    PSOs will record data to estimate the numbers of marine mammals 
exposed to various received sound levels and to document apparent 
disturbance reactions or lack thereof. Data will be used to estimate 
numbers of animals potentially `taken' by harassment (as defined in the 
MMPA). They will also provide information needed to order a shut-down 
of the airguns when a marine mammal is within or near the EZ. 
Observations will also be made during daytime periods when the Thompson 
is underway without seismic operations (i.e., transits to, from, and 
through the study area) to collect baseline biological data.
    When a sighting is made, the following information about the 
sighting will be recorded:
    1. Species, group size, age/size/sex categories (if determinable), 
behavior when first sighted and after initial sighting, heading (if 
consistent), bearing and distance from seismic vessel, sighting cue, 
apparent reaction to the airguns or vessel (e.g., none, avoidance, 
approach, paralleling, etc.), and behavioral pace.
    2. Time, location, heading, speed, activity of the vessel, Beaufort 
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 as well as information regarding shut-downs of the 
seismic source, will be recorded in a standardized format. The data 
accuracy will be verified by the PSOs at sea, and preliminary reports 
will be prepared during the field program and summaries forwarded to 
the operating institution's shore facility and to NSF weekly or more 
frequently.
    Vessel-based observations by the PSO will provide:
    1. The basis for real-time mitigation (airgun shut-down).
    2. Information needed to estimate the number of marine mammals 
potentially taken by harassment, which must be reported to NMFS.
    3. Data on the occurrence, distribution, and activities of marine 
mammals in the area where the seismic study is conducted.
    4. Information to compare the distance and distribution of marine 
mammals relative to the source vessel at times with and without seismic 
activity.
    5. Data on the behavior and movement patterns of marine mammals 
seen at times with and without seismic activity.
    SIO will submit a report to NMFS and NSF within 90 days after the 
end of the cruise. The report will describe the operations that were 
conducted and sightings of marine mammals near the operations. The 
report will provide full documentation of methods, results, and 
interpretation pertaining to all monitoring. The 90-day report will

[[Page 45536]]

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 potential 
``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 this IHA, 
such as an injury (Level A harassment), serious injury or mortality 
(e.g., ship-strike, gear interaction, and/or entanglement), SIO will 
immediately cease the specified activities and immediately report the 
incident to the Chief of the Permits, Conservation, and Education 
Division, Office of Protected Resources, NMFS at 301-427-8401 and/or by 
e-mail to [email protected] and [email protected], and the 
NMFS Pacific Islands Regional Office 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 SIO to 
determine what is necessary to minimize the likelihood of further 
prohibited take and ensure MMPA compliance. SIO may not resume their 
activities until notified by NMFS via letter or e-mail, or telephone.
    In the event that SIO discovers an injured or dead marine mammal, 
and the lead PSO determines that the cause of the injury or death is 
unknown and the death is relatively recent (i.e., in less than a 
moderate state of decomposition as described in the next paragraph), 
SIO will immediately report the incident to the Chief of the Permits, 
Conservation, and Education Division, Office of Protected Resources, 
NMFS, at 301-427-8401, and/or by e-mail to [email protected] and 
[email protected], and the NMFS Pacific Islands Regional Office 
(808-944-2269) and/or by e-mail to the Pacific Islands Regional 
Stranding Coordinator ([email protected]). The report must 
include the same information identified in the paragraph above. 
Activities may continue while NMFS reviews the circumstances of the 
incident. NMFS will work with SIO to determine whether modifications in 
the activities are appropriate.
    In the event that SIO discovers an injured or dead marine mammal, 
and the lead PSO determines that the injury or death is not associated 
with or related to the activities authorized in the IHA (e.g., 
previously wounded animal, carcass with moderate to advanced 
decomposition, or scavenger damage), SIO will report the incident to 
the Chief of the Permits, Conservation, and Education Division, Office 
of Protected Resources, NMFS, at 301-427-8401, and/or by e-mail to 
[email protected] and [email protected], and the NMFS 
Pacific Islands Regional Office (808-944-2269), and/or by e-mail to the 
Pacific Islands Regional Stranding Coordinator 
([email protected]), within 24 hours of discovery. SIO will 
provide photographs or video footage (if available) or other 
documentation of the stranded animal sighting to NMFS and the Marine 
Mammal Stranding Network.
Estimated Take by Incidental Harassment
    Except with respect to certain activities not pertinent here, the 
MMPA defines ``harassment'' as:

any act of pursuit, torment, or annoyance which (i) has the 
potential to injure a marine mammal or marine mammal stock in the 
wild [Level A harassment]; or (ii) has the potential to disturb a 
marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering 
[Level B harassment].

    Only take by Level B harassment is anticipated and proposed to be 
authorized as a result of the proposed marine geophysical survey in the 
western tropical 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 SIO seeks the IHA. The required 
mitigation and monitoring measures will minimize any potential risk for 
injury, serious injury, or mortality.
    The following sections describe SIO's methods to estimate take by 
incidental harassment and present the applicant's estimates of the 
numbers of marine mammals that could be affected during the proposed 
seismic program. The estimates are based on a consideration of the 
number of marine mammals that could be disturbed appreciably by 
operations with the two GI airgun array to be used during approximately 
1,600 km of survey lines in the western tropical Pacific Ocean.
    SIO 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, SIO provides no 
additional allowance for animals that could be affected by sound 
sources other than airguns.
    Extensive systematic ship-based surveys have been conducted by NMFS 
Southwest Fisheries Science Center (SWFSC) for marine mammals in the 
eastern, but not the western tropical Pacific Ocean. A systematic 
vessel-based marine mammal survey was conducted approximately 2,500 km 
(1,349.9 nmi) west of the proposed survey area in the Commonwealth of 
the Northern Mariana Islands (CNMI) for the U.S. Navy during January to 
April, 2007 (SRS-Parsons et al., 2007; Fulling et al., in press). The 
cruise area was defined by the boundaries 10[deg] to 18[deg] North, 
142[deg] to 148[deg] East, encompassing an area approximately 585,000 
km\2\ (170,558.7 nmi\2\) including the islands of Guam and the southern 
CNMI. The survey was conducted using standard line-transect protocols 
developed by NMFS SWFSC. Observers visually surveyed 11,033 km (5,957.3 
nmi) of trackline, mostly in high sea states (88% of the time in 
Beaufort Sea states four to six). Another survey was conducted by SWFSC 
approximately 3,500 km (1,889.8 nmi) east of the proposed survey area 
in the EEZ around Hawaii during August to November, 2002;

[[Page 45537]]

survey effort was 3,550 km (1,916.8 nmi) in the ``Main Island 
stratum,'' which had a surface area of 2,240,024 km\2\ (653086.5 
nmi\2\) (Barlow, 2006).
    SIO used densities that were the effort-weighted means for the CNMI 
(Fulling et al., in press) and the outer EEZ stratum of Hawaii (Barlow, 
2006). The densities had been corrected, by the original authors, for 
trackline detection probability bias, and for data from Hawaii, for 
availability bias. Trackline detection probability bias is associated 
with diminishing sightability with increasing lateral distance from the 
trackline, and is measured by [fnof](0). Availability bias refers to 
the fact that there is less-than-100% probability of sighting an animal 
that is present along the survey trackline [fnof](0), and it is 
measured by g(0). Fulling et al. (in press) did not correct the CNMI 
densities for availability bias (i.e., it was assumed that g(0)=1), 
which resulted in underestimates of density. The densities are given in 
Table 3 of SIO's IHA application.
    There is some uncertainty about the representativeness of the data 
and the assumptions used in the calculations, for example:
    (1) The timing of most of the surveys was different, the CNMI 
survey was from January to April, the Hawaii survey was from August to 
November, and the proposed SIO survey is from November to December;
    (2) Locations were also different, with the proposed survey area 
approximately 2,500 km east of the CNMI and approximately 3,500 km west 
of Hawaii; and
    (3) Most of the Marianas survey was in high sea states that would 
have prevented detection of many marine mammals, especially cryptic 
species such as beaked whales and Kogia spp.
    However, the approach used here is believed to be the best 
available approach.
    SIO's estimates of exposures to various sound levels assume that 
the proposed surveys will be fully completed; in fact, the ensonified 
areas calculated using the planned number of line-km have been 
increased by 25% to accommodate turns, lines that may need to be 
repeated, equipment testing, etc. As is typical during offshore ship 
surveys, inclement weather and equipment malfunctions are likely to 
cause delays and may limit the number of useful line-kilometers of 
seismic operations that can be undertaken. Furthermore, any marine 
mammal sightings within or near the designated EZs will result in the 
shut-down of seismic operations as a mitigation measure. Thus, the 
following estimates of the numbers of marine mammals potentially 
exposed to sound levels of 160 dB re 1 [mu]Pa (rms) are precautionary 
and probably overestimate the actual numbers of marine mammals that 
might be involved. These estimates also assume that there will be no 
weather, equipment, or mitigation delays, which is highly unlikely.
    SIO estimated the number of different individuals that may be 
exposed to airgun sounds with received levels greater than or equal to 
160 dB re 1 [mu]Pa (rms) on one or more occasions by considering the 
total marine area that would be within the 160 dB radius around the 
operating airgun array on at least one occasion, along with the 
expected density of marine mammals in the area. The proposed seismic 
lines do not run parallel to each other in close proximity and the 
ensonified areas do not overlap, thus an individual mammal that was 
stationary would be exposed once during the proposed survey.
    The numbers of different individuals potentially exposed to greater 
than or equal to 160 dB (rms) were calculated by multiplying the 
expected species density times the anticipated area to be ensonified. 
The area was determined by entering the planned survey lines into a 
MapInfo GIS, using the GIS to identify the relevant areas by 
``drawing'' the applicable 160 dB buffer (see Table 1 of the IHA 
application) around each seismic line, and then calculating the total 
area within the buffers. For this survey, there were no areas of 
overlap because of crossing lines.
    Applying the approach described above, approximately 2,144 km\2\ 
(625.1 nmi\2\) (approximately 2,680 km\2\ [781.4 nmi\2\] including the 
25% contingency) would be within the 160 dB isopleth on one or more 
occasions during the proposed survey. Because this approach does not 
allow for turnover in the marine mammal populations in the study area 
during the course of the survey, the actual number of individuals 
exposed could be underestimated, although the conservative (i.e., 
probably overestimated) line-kilometer distances used to calculate the 
area may offset this. Also, the approach assumes that no cetaceans will 
move away from or toward the trackline as the Thompson approaches in 
response to increasing sound levels prior to the time the levels reach 
160 dB. Another way of interpreting the estimates that follow is that 
they represent the number of individuals that are expected (in the 
absence of a seismic program) to occur in the waters that will be 
exposed to greater than or equal to 160 dB re 1 [micro]Pa (rms).
    Table 3 (Table 4 of the IHA application) shows the estimates of the 
number of different individual marine mammals that potentially could be 
exposed to greater than or equal to 160 dB re 1 [mu]Pa (rms) during the 
seismic survey if no animals moved away from the survey vessel. The 
requested take authorization is given in Table 3 (below; the far right 
column of Table 4 of the IHA application). For ESA listed species, the 
requested take authorization has been increased to the mean group size 
in the CNMI (Fulling et al., in press) for the particular species in 
cases where the calculated number of individuals exposed was between 
0.05 and the mean group size (i.e., for the sei whale). For species not 
listed under the ESA that could occur in the study area, the requested 
take authorization has been increased to the mean group size in the 
CNMI (Fulling et al., in press) or, for species not sighted in the CNMI 
survey, Hawaii (Barlow, 2006) for the particular species in cases where 
the calculated number of individuals exposed was between 1 and the mean 
group size.
    The estimate of the number of individual cetaceans that could be 
exposed to seismic sounds with received levels greater than or equal to 
160 dB re 1 [mu]Pa (rms) during the proposed survey is 118 (see Table 4 
of the IHA application). That total includes 1 Bryde's whale, 6 sperm 
whales, 5 pygmy sperm whales, 12 dwarf sperm whales, 10 Cuvier's beaked 
whales, 1 Longman's beaked whale, 2 Blainville's beaked whales, 5 
rough-toothed dolphins, 2 bottlenose dolphins, 30 pantropical spotted 
dolphins, 5 spinner dolphins, 16 striped dolphins, 7 Fraser's dolphins, 
1 Risso's dolphin, 7 melon-headed whales, 2 false killer whales, and 6 
short-finned pilot whales which would represent less than 0.01%, 0.02%, 
NA, less than 0.01%, 0.05%, NA, less than 0.01%, less than 0.01%, less 
than 0.01%, less than 0.01%, less than 0.01%, less than 0.01%, less 
than 0.01%, less than 0.01%, 0.02%, less than 0.01%, and less than 
0.01% of the regional populations, respectively. Most (68.6%) of the 
cetaceans potentially exposed are delphinids; pantropical spotted, 
striped, and Fraser's dolphins are estimated to be the most common 
species in the proposed study area.
BILLING CODE 3510-22-P

[[Page 45538]]

[GRAPHIC] [TIFF OMITTED] TN29JY11.006

BILLING CODE 3510-22-C

Encouraging and Coordinating Research

    SIO and NSF will coordinate the planned marine mammal monitoring 
program associated with the seismic survey in the western tropical 
Pacific Ocean with any parties that may have or express an interest in 
the proposed seismic survey. UW will work with the U.S. Department of 
State to obtain the necessary approvals for operating in the foreign 
EEZ of the Republic of the Marshall Islands.

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 evaluated factors such as:
    (1) The number of anticipated injuries, serious injuries, or 
mortalities;
    (2) The number, nature, and intensity, and duration of Level B 
harassment (all relatively limited);

[[Page 45539]]

    (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, and 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 (i.e., 
the manner and degree in which the measure is likely to reduce adverse 
impacts to marine mammals, the likely effectiveness of the measures, 
and the practicability of implementation).
    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 above);
    (3) The fact that pinnipeds would have to be closer than 20 m (65.6 
ft) in deep water when the two GI airgun array is in use at 3 m (9.8 
ft) tow depth from the vessel to be exposed to levels of sound believed 
to have even a minimal chance of causing PTS;
    (4) The fact that cetaceans would have to be closer than 70 m 
(229.7 ft) in deep water when the two GI airgun array is in 3 m tow 
depth from the vessel to be exposed to levels of sound believed to have 
even a minimal chance of causing PTS; and
    (5) The likelihood that marine mammal detection ability by trained 
PSOs is high at close proximity to the vessel.
    No injuries, serious injuries, or mortalities are anticipated to 
occur as a result of SIO's planned marine seismic survey, and none are 
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 in this document outlines the number of 
Level B harassment takes that are anticipated as a result of the 
activities. Due to the nature, degree, and context of Level B 
(behavioral) harassment anticipated and described (see Potential 
Effects on Marine Mammals section above) in this notice, the activity 
is not expected to impact rates of recruitment or survival for any 
affected species or stock.
    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 32 days and 
the Thompson will be continuously moving along planned tracklines. 
Therefore, the seismic survey will be increasing sound levels in the 
marine environment surrounding the vessel for several weeks in the 
study area. Of the 26 marine mammal species under NMFS jurisdiction 
that are known to or likely to occur in the study area, six are listed 
as threatened or endangered under the ESA: humpback, sei, fin, blue, 
sperm, and Hawaiian monk seals. These species are also considered 
depleted under the MMPA. The Hawaiian monk seal population has 
generally been decreasing (the main Hawaiian islands population appears 
to be increasing). There is generally insufficient data to determine 
population trends for the other depleted species in the study area. To 
protect these animals (and other marine mammals in the study area), SIO 
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 19 species of marine 
mammals under its jurisdiction could be potentially affected by Level B 
harassment over the course of the proposed IHA. For each species, these 
numbers are small (each less than one percent) relative to the regional 
population size. The population estimates for the marine mammal species 
that may be taken by harassment were provided in Table 2 of this 
document.
    NMFS's practice has been to apply the 160 dB re 1 [micro]Pa (rms) 
received level threshold for underwater impulse sound levels to 
determine whether take by Level B harassment occurs. Southall et al. 
(2007) provide a severity scale for ranking observed behavioral 
responses of both free-ranging marine mammals and laboratory subjects 
to various types of anthropogenic sound (see Table 4 in Southall et al. 
[2007]).
    NMFS has preliminarily determined, provided that the aforementioned 
mitigation and monitoring measures are implemented, that the impact of 
conducting a marine geophysical survey in the western tropical Pacific 
Ocean, November to December, 2011, may result, at worst, in a temporary 
modification in behavior and/or low-level physiological effects (Level 
B harassment) of small numbers of certain species of marine mammals. 
See Table 3 (above) 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 SIO'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.

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

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

[[Page 45540]]

area, several are listed as endangered under the ESA, including the 
humpback, sei, fin, blue, and sperm whales, as well as the Hawaiian 
monk seal. Under section 7 of the ESA, NSF has initiated formal 
consultation with the NMFS, Office of Protected Resources, Endangered 
Species Division, on this proposed seismic survey. NMFS's Office of 
Protected Resources, Permits, Conservation and Education Division, has 
initiated formal consultation under Section 7 of the ESA with NMFS's 
Office of Protected Resources, Endangered Species Division, to obtain a 
Biological Opinion evaluating the effects of issuing the IHA on 
threatened and endangered marine mammals and, if appropriate, 
authorizing incidental take. NMFS will conclude formal section 7 
consultation prior to making a determination on whether or not to issue 
the IHA. If the IHA is issued, NSF and SIO, in addition to the 
mitigation and monitoring requirements included in the IHA, will be 
required to comply with the Terms and Conditions of the Incidental Take 
Statement corresponding to NMFS's Biological Opinion issued to both NSF 
and NMFS's Office of Protected Resources.

National Environmental Policy Act (NEPA)

    With its complete application, NSF and SIO provided NMFS a draft EA 
analyzing the direct, indirect, and cumulative environmental impacts of 
the proposed specified activities on marine mammals including those 
listed as threatened or endangered under the ESA. The draft EA, 
prepared by NSF incorporates a document prepared by LGL on behalf of 
NSF and SIO. It is entitled ``Environmental Assessment of a Low-Energy 
Marine Geophysical Survey by the R/V Thompson in the Western Tropical 
Pacific Ocean, November-December 2011.'' Prior to making a final 
decision on the SIO application, NMFS will either prepare an 
independent EA, or, after review and evaluation of the SIO EA for 
consistency with the regulations published by the Council of 
Environmental Quality (CEQ) and NOAA Administrative Order 216-6, 
Environmental Review Procedures for Implementing the National 
Environmental Policy Act, adopt the NSF EA and make a decision of 
whether or not to issue a Finding of No Significant Impact (FONSI).

Proposed Authorization

    NMFS proposes to issue an IHA to SIO for conducting a marine 
geophysical survey in the western tropical 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: July 25, 2011.
Helen M. Golde,
Deputy Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2011-19244 Filed 7-28-11; 8:45 am]
BILLING CODE 3510-22-P