Takes of Marine Mammals Incidental to Specified Activities; Marine Geophysical Survey in the Northwest Pacific Ocean, July Through September, 2010, 44770-44781 [2010-18660]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 75, Number 145 (Thursday, July 29, 2010)]
[Notices]
[Pages 44770-44781]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-18660]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XX45


Takes of Marine Mammals Incidental to Specified Activities; 
Marine Geophysical Survey in the Northwest Pacific Ocean, July Through 
September, 2010

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

ACTION: Notice; issuance of an incidental take authorization.

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SUMMARY: In accordance with the Marine Mammal Protection Act (MMPA) 
regulations, notification is hereby given that NMFS has issued an 
Incidental Harassment Authorization (IHA) to Lamont-Doherty Earth 
Observatory (L-DEO), a part of Columbia University, to take small 
numbers of marine mammals, by harassment, incidental to conducting a 
marine geophysical survey at the Shatsky Rise in the northwest Pacific 
Ocean, July through September, 2010.

DATES: Effective July 19, 2010, through September 28, 2010.

ADDRESSES: A copy of the IHA and application are available by writing 
to P. Michael Payne, Chief, Permits, Conservation and Education 
Division, Office of Protected Resources, National

[[Page 44771]]

Marine Fisheries Service, 1315 East-West Highway, Silver Spring, MD 
20910 or by telephoning the contacts listed here. 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: https://www.nmfs.noaa.gov/pr/permits/incidental.htm#applications. The following associated documents are 
also available at the same internet address: Environmental Assessment 
(EA) prepared by NMFS, and the finding of no significant impact 
(FONSI). The NMFS Biological Opinion will be available online at: 
https://www.nmfs.noaa.gov/pr/consultation/opinions.htm. Documents cited 
in this notice may be viewed, by appointment, during regular business 
hours, at the aforementioned address. Documents cited in this notice 
may be viewed, by appointment, during regular business hours, at the 
aforementioned address.

FOR FURTHER INFORMATION CONTACT: Jeannine Cody, Office of Protected 
Resources, NMFS, (301) 713-2289, ext. 113 or Benjamin Laws, Office of 
Protected Resources, NMFS, (301) 713-2289, ext. 159.

SUPPLEMENTARY INFORMATION:

Background

    Section 101(a)(5)(D) of the MMPA (16 U.S.C. 1371(a)(5)(D)) directs 
the Secretary of Commerce to authorize, upon request, the incidental, 
but not intentional, taking of small numbers of marine mammals of a 
species or population stock, by United States citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and, if the taking is 
limited to harassment, a notice of a proposed authorization is provided 
to the public for review.
    Authorization for 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. 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 
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.
    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 February 2, 2010 from L-DEO for the 
taking by harassment, of marine mammals, incidental to conducting a 
marine geophysical survey in the northwest Pacific Ocean. L-DEO, with 
research funding from the U.S. National Science Foundation (NSF), plans 
to conduct a marine seismic survey in the northwest Pacific Ocean, from 
July through September, 2010.
    L-DEO plans to use one source vessel, the R/V Marcus G. Langseth 
(Langseth), a seismic airgun array, and ocean bottom seismometers (OBS) 
to conduct a geophysical survey at the Shatsky Rise, a large igneous 
plateau in the northwest Pacific Ocean. The survey will provide data 
necessary to decipher the crustal structure of the Shatsky Rise; may 
address major questions of Earth history, geodynamics, and tectonics; 
could impact the understanding of terrestrial magmatism and mantle 
convection; and may obtain data that could be used to improve estimates 
of regional earthquake occurrence and distribution. In addition to the 
operations of the seismic airgun array, L-DEO intends to operate a 
multibeam echosounder (MBES) and a sub-bottom profiler (SBP) 
continuously throughout the survey.
    Acoustic stimuli (i.e., increased underwater sound) generated 
during the operation of the seismic airgun array, may have the 
potential to cause marine mammals in the survey area to be behaviorally 
disturbed in a manner that NMFS considers to be Level B harassment. 
This is the principal means of marine mammal taking associated with 
these activities and L-DEO has requested an authorization to take 
several marine mammals by Level B harassment.
Description of the Specified Activity
    L-DEO's seismic survey on the Shatsky Rise is scheduled to commence 
on July 24, 2010, and continue for approximately 17 days ending on 
September 7, 2010. L-DEO will operate the Langseth to deploy an airgun 
array, deploy and retrieve OBS, and tow a hydrophone streamer to 
complete the survey.
    The Langseth will transit to the Shatsky Rise, located at 30-37 
[deg]N, 154-161[deg]E in international waters offshore from Japan. Some 
minor deviation from these dates is possible, depending on logistics, 
weather conditions, and the need to repeat some lines if data quality 
is substandard. Therefore, NMFS plans to issue an authorization that 
extends to September 28, 2010.
    Geophysical survey activities will involve conventional seismic 
methodologies to decipher the crustal structure of the Shatsky Rise. To 
obtain high-resolution, 3-D structures of the area's magmatic systems 
and thermal structures, the Langseth will deploy a towed array of 36 
airguns as an energy source and approximately 28 OBSs and a 6-kilometer 
(km) long hydrophone streamer. As the airgun array is towed along the 
survey lines, the hydrophone streamers will receive the returning 
acoustic signals and transfer the data to the vessel's onboard 
processing system. The OBSs record the returning acoustic signals 
internally for later analysis.
    The Shatsky Rise study (e.g., equipment testing, startup, line 
changes, repeat coverage of any areas, and equipment recovery) will 
take place in international waters deeper than 1,000 meters (m) (3,280 
feet (ft)) and will require approximately 17 days (d) to complete 
approximately 15 transects of variable lengths totaling 3,160 
kilometers (km) of survey lines. Data acquisition will include 
approximately 408 hours (hr) of airgun operation (17 d x 24 hr).
    The scientific team consists of Drs. Jun Korenaga (Yale University, 
New Haven, CT), and William Sager (Texas A&M University, College 
Station, TX).
    NMFS outlined the purpose of the program in a previous notice for 
the proposed IHA (75 FR 28568, May 21,

[[Page 44772]]

2010). The activities to be conducted have not changed between the 
proposed IHA notice and this final notice announcing the issuance of 
the IHA. For a more detailed description of the authorized action, 
including vessel and acoustic source specifications, the reader should 
refer to the proposed IHA notice (75 FR 28568, May 21, 2010).

Comments and Responses

    A notice of receipt of the L-DEO application and proposed IHA was 
published in the  Federal Register on May 21, 2010 (75 FR 28568). 
During the comment period, NMFS received comments from the Marine 
Mammal Commission (Commission). The public comments can be found online 
at: https://www.nmfs.noaa.gov/pr/permits/incidental.htm. Following are 
their comments and NMFS' responses.
    Comment 1: The Commission recommends that before issuing the 
requested IHA, NMFS provide additional justification for its 
preliminary determination that the planned monitoring program will be 
sufficient to detect with a high level of confidence, all marine 
mammals within or entering the identified exclusion zones.
    Response: NMFS believes that the planned monitoring program will be 
sufficient to detect (using visual detection and PAM), with reasonable 
certainty, most marine mammals within or entering identified exclusion 
zones (EZs). This monitoring, along with the required mitigation 
measures, will result in the least practicable adverse impact on the 
affected species or stocks and will result in a negligible impact on 
the affected species or stocks.
    At present, NMFS views the combination of visual and passive 
acoustic monitoring as the most effective mitigation techniques 
available for detecting marine mammals within or entering the exclusion 
zone. L-DEO and the federal funding agency (NSF) are receptive to 
incorporating proven technologies and techniques to enhance the current 
monitoring and mitigation program. Until proven technological advances 
are made, nighttime mitigation measures during operations include 
combinations of the use of protected species visual observers (PSVOs), 
PAM, night vision devices, and continuous shooting of a mitigation gun. 
Should the airgun array be powered-down, it is believed that the 
operation of a single airgun continues to serve as a sound source 
deterrent to marine mammals. In the event of a complete airgun array 
shut down, for mitigation or repairs, then science is suspended until 
one half hour after civil dawn (when PSO's are able to clear the safety 
zone). Science does not begin until the entire safety radius is visible 
for at least 30 minutes.
    In cooperation with NMFS, L-DEO will be conducting efficacy 
experiments of night vision devices (NVD) during a future Langseth 
cruise. In addition, in response to a recommendation from NMFS, L-DEO 
is evaluating the use of handheld thermal imaging cameras to supplement 
nighttime mitigation practices. These devices are currently 
successfully utilized by another federal agency while conducting 
nighttime seismic operations.
    Comment 2: The Commission recommends that NMFS require the 
applicant to use location-specific environmental parameters to re-
estimate exclusion zones and verify the estimates with field 
measurements prior to or at the beginning of the study.
    Response: L-DEO and the NSF have invested significant resources 
into the Langseth's seismic equipment calibration studies. The data 
results from the studies were peer reviewed and the calibration 
results, viewed as conservative, were used to determine the cruise-
specific exclusion zones. With the expected low density of marine 
mammals, combined with the remote, deep water survey location, NMFS has 
determined that the exclusion zones identified in the IHA are 
appropriate for the survey.
    Comment 3: The Commission recommends that NMFS require the 
applicant to re-estimate exposures based upon location-specific 
environmental parameters and associated ensonified areas.
    Response: See the response to Comment 2. NMFS has concluded that 
the exposures estimated in the IHA are appropriate for this survey.
    Comment 4: Clarify the qualifiers ``when practical,'' ``if 
practical,'' and ``when feasible'' with respect to: (1) Using two 
marine mammal observers to monitor the exclusion zone for marine 
mammals during daytime operations and nighttime start-ups of the 
airguns; (2) using crew members to assist observers in detecting marine 
mammals and implementing mitigation requirements; and (3) using marine 
mammal observers during daytime periods to compare sighting rates and 
animal behavior during times when seismic airguns are and are not 
operating.
    Response: The Langseth typically carries five trained, NMFS-
qualified and experienced PSVOs for every seismic study involving use 
of an airgun system comparable to that planned for the upcoming 
project. PSVOs are appointed by L-DEO with NMFS concurrence. L-DEO will 
utilize two (except during meal times and restroom breaks), NMFS-
qualified, vessel-based PSVOs to watch for and monitor marine mammals 
near the seismic source vessel during all daytime airgun operations and 
before and during start-ups of airguns day or night. PSVOs will have 
access to reticle binoculars, big-eye binoculars, and night vision 
devices to scan the area around the vessel. PSVOs will alternate 
between binoculars and the naked eye to avoid eye fatigue. During all 
daytime periods, two PSVOs will be on duty from the observation tower 
to monitor. During mealtimes it is sometimes difficult to have two 
PSVOs on effort, but at least one PSVO will be on watch during bathroom 
breaks and mealtimes. Use of two simultaneous observers increases the 
effectiveness of detecting animals near the source vessel. However, 
during meal times, only one PSVO may be on duty.
    The complement of five PSVOs will rotate shifts, with generally 
three PSVOs typically on watch at a time, with duty shifts lasting 
typically one to four hours. Two PSVOs will also be on visual watch 
during all nighttime start-ups of the seismic airguns. A third PSVO 
will monitor the PAM equipment 24 hours a day to detect vocalizing 
marine mammals present in the action area. In summary, a typical 
daytime cruise would have scheduled two PSVOs on duty from the 
observation tower, a third PSVO on PAM, and a fourth and fifth PSVO off 
duty in preparation for shifts.
    L-DEO will also instruct the Langseth crew to assist in detecting 
marine mammals and turtles and implementing mitigation requirements.
    Last, PSVOs will conduct observations during daytime periods when 
the seismic system is not operating for comparison of sighting rates 
and behavior both with versus without airgun operations and between 
acquisition periods.
    Comment 5: Propose to L-DEO that it revise its study design to add 
pre- and post-seismic survey assessments as a way of obtaining more 
realistic baseline sighting rates for marine mammals, as well as better 
assessment of impacts and recovery from those impacts.
    Response: Extending the survey is not practicable from an 
operational standpoint for the applicant. Due to the remote location of 
the survey and the length of time needed to conduct the requested 
science experiment, there is little time left for the vessel to operate 
without the need for refueling and servicing.
    During the cruise, there will be significant amounts of transit 
time pre-and post-survey during which PSVOs

[[Page 44773]]

will be on watch (e.g., prior-to and after seismic portions of the 
survey and during the deployment and retrieval of the OBSs. Considering 
the low marine mammal density anticipated at this survey site, it is 
unlikely that the information would result in any statistically robust 
conclusions for this particular seismic survey.
    Comment 6: Clarify the qualifier ``ideally,'' including the 
conditions under which the towed hydrophones would not be monitored, 
and clarify and describe the conditions that it assumes would render 
the use of passive acoustic monitoring impracticable for supplementing 
the visual monitoring program.
    Response: The primary PAM streamer on the Langseth is a digital 
hydrophone streamer. Should the digital streamer fail, back-up systems 
should include an analog spare streamer and a hull-mounted hydrophone. 
Every effort would be made to have a working PAM system during the 
cruise. In the unlikely event that all three of these systems were to 
fail, L-DEO would continue science acquisition with the visual based 
PSVO program. Until further technological advances are made with the 
PAM system, it is still viewed as a supplementary enhancement to the 
visual monitoring program. If weather conditions were to prevent the 
use of PAM, then conditions would also likely prevent the use of the 
airgun array.
    The towed hydrophones will ideally be monitored 24 hours per day 
while at the seismic survey area during airgun operations, and during 
most periods when the Langseth is underway while the airguns are not 
operating; PAM may not be possible if damage occurs to both the primary 
and back-up hydrophone arrays during operations.
    Comment 7: Extend the monitoring period to at least one hour before 
initiation of seismic activities and at least one hour before the 
resumption of airgun activities after a shutdown because of a marine 
mammal sighting within an exclusion zone.
    Response: As the Commission points out, several species of deep-
diving cetaceans are capable of remaining underwater for more than 30 
minutes; however, for the following reasons NMFS believes that 30 
minutes is an adequate length for the monitoring period prior to the 
start-up of airguns:
    (1) Because the Langseth is required to monitor before ramp-up of 
the airgun array, the time of monitoring prior to start-up of any but 
the smallest array is effectively longer than 30 minutes (ramp-up will 
begin with the smallest airgun in the array and airguns will be added 
in sequence such that the source level of the array will increase in 
steps not exceeding approximately 6 dB per 5 minute period over a total 
duration of 20 to 30 minutes);
    (2) In many cases PSVOs are making observations during times when 
the seismic airguns are not being operated and will actually be 
observing prior to the 30-minute observation period anyway;
    (3) The majority of the species that may be exposed do not stay 
underwater more than 30 minutes; and
    (4) All else being equal and if deep-diving individuals happened to 
be in the area in the short time immediately prior to the pre-start-up 
monitoring, if an animal's maximum underwater dive time is 45 minutes, 
then there is only a one in three chance that the last random surfacing 
would occur prior to the beginning of the required 30-minute monitoring 
period and that the animal would not be seen during that 30-minue 
period.
    Also, seismic vessels are moving continuously (because of the long, 
towed array) and NMFS believes that unless the animal submerges and 
follows at the speed of the vessel (highly unlikely, especially when 
considering that a significant part of their movements is vertical 
[deep-diving]), the vessel will be far beyond the length of the 
exclusion zone (EZ) radii within 30 minutes, and therefore it will be 
safe to start the airguns again.
    The effectiveness of monitoring is science-based and the 
requirement that mitigation measures be ``practicable.'' NMFS believes 
that the framework for visual monitoring will: (1) Be effective at 
spotting almost all species for which take is requested; and (2) that 
imposing additional requirements, such as those suggested by the 
Commission, would not meaningfully increase the effectiveness of 
observing marine mammals approaching or entering the EZs.
    Comment 8: The Commission recommends that, before issuing the 
requested IHA, NMFS require that observers collect and analyze data on 
the effectiveness of ramp-up as a mitigation measure during all such 
procedures.
    Response: The IHA requires that PSVOs on the Langseth make 
observations for 30 minutes prior to ramp-up, during all ramp-ups, and 
during all daytime seismic operations and record the following 
information when a marine mammal is sighted:
    (i) 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 including responses to ramp-up), and 
behavioral pace; and
    (ii) Time, location, heading, speed, activity of the vessel 
(including number of airguns operating and whether in state of ramp-up 
or power-down), Beaufort wind force sea state, visibility, and sun 
glare.
    One of the primary purposes of monitoring is to result in 
``increased knowledge of the species'' and the effectiveness of 
monitoring and mitigation measures; the effectiveness of marine 
mammal's reaction to ramp-up would be useful information in this 
regard. NMFS has asked NSF and L-DEO to gather all data that could 
potentially provide information regarding the effectiveness of ramp-ups 
as a mitigation measure. However, considering the low numbers of marine 
mammal sightings and low numbers of ramp-ups, it is unlikely that the 
information will result in any statistically robust conclusions for 
this particular seismic survey. Over the long term, these requirements 
may provide information regarding the effectiveness of ramp-up as a 
mitigation measure, provided animals are detected during ramp-up.
    Post-cruise monitoring reports required by the IHA contain vast 
amounts of sighting data. LGL Ltd., Environmental Research Associates 
(LGL), a contractor for L-DEO, has processed sighting and density and 
data, and their publications can be viewed online at: https://www.lgl.com/index.php?option=com_content&view=article&id=69&Itemid=162&lang=en. Post-cruise monitoring 
reports are currently available on the NMFS MMPA Incidental Take 
Program Web site and future reports will also be available on the NSF 
Web site should there be interest in further analysis of this data by 
the public.
    Comment 9: The Commission requests that NMFS work with the 
applicant to correct discrepancies within the application and between 
the application and Federal Register notice. The last paragraph of page 
8 of the application states that ``[t]hirty-three cetacean species 
including 26 odontocete species and seven mysticetes may occur in the 
Shatsky Rise area * * *'' but then goes on to state that the 
``[i]nformation on the occurrence, distribution, population size, and 
conservation status for each of the 34 marine mammal species that may 
occur in the study area is presented in Table 2. The text of the notice 
refers to 34 species of marine mammals that

[[Page 44774]]

could be taken by harassment, but Table 3 in the notice lists only 32 
species.
    Response: NMFS could find no discrepancies in L-DEO's application 
between the last paragraph on page 8 and Table 2. The application 
discussed 33 species which included 26 odontocetes, seven mysticetes 
and the addition of one pinniped, the northern fur seal (Callorhinus 
ursinus), totaling 34 species shown in Table 2.
    Please note that Table 3 combines three cryptic species (Ginkgo-
toothed beaked whale, Stejneger's beaked whale, and Hubb's beaked whale 
into one category, named Mesoplodon spp.; thus reducing the number of 
species listed in Table 3 by two for a total of 32 species. However, 
the total number of species that could be taken by harassment remains 
at 34 animals.
    Comment 10: The Commission requests that NMFS advise the applicant 
of the need to use the 160-dB re 1 [micro]Pa(rms) threshold 
for all cetaceans as currently used by the Service or to explain the 
bases for using some other sound level as the appropriate threshold.
    Response: The applicant understands that the 170-dB level is 
currently not an accepted threshold level for an authorization from 
NMFS. The requested takes are based on the 160-dB level.
    In closing, NMFS is open to meeting with the Commission to further 
discuss the broad issues raised in their comments, which relate to more 
than just the IHA contemplated here. NMFS' staff has contacted 
Commission staff in response to this request and will follow up to 
schedule a meeting this year.

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

    Thirty-four marine mammal species may occur in the Shatsky Rise 
survey area, including 26 odontocetes (toothed cetaceans), 7 mysticetes 
(baleen whales) and one pinniped. Six of these species are listed as 
endangered under the U.S. Endangered Species Act of 1973 (ESA; 16 
U.S.C. 1531 et seq.), including the north Pacific right (Eubalena 
japonica), humpback (Megaptera novaeangliae), sei (Balaenoptera 
borealis), fin (Balaenoptera physalus), blue (Balaenoptera musculus), 
and sperm (Physeter macrocephalus) whale.
    The western North Pacific gray whale (Eschrichtius robustus) occurs 
in the northwest Pacific Ocean and is listed as endangered under the 
ESA and as critically endangered by the International Union for 
Conservation of Nature (IUCN). L-DEO does not expect to encounter this 
species within the survey area as gray whales are known to prefer 
nearshore coastal waters. Thus, L-DEO does not present analysis for 
this species nor does the application request take for this species.
    NMFS has presented a more detailed discussion of the status of 
these stocks and their occurrence in the northeastern Pacific Ocean, as 
well as other marine mammal species that occur around Shatsky Rise, in 
the notice of the proposed IHA (75 FR 28568, May 21, 2010).

Potential Effects on Marine Mammals

Summary of Potential Effects of Airgun Sounds

    Level B harassment of cetaceans and pinnipeds has the potential to 
occur during the seismic survey due to acoustic stimuli caused by the 
firing of a single airgun or the 36-airgun array which introduces sound 
into the marine environment. The effects of sounds from airguns 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 project would result in any cases of temporary or permanent 
hearing impairment, or any significant non-auditory physical or 
physiological effects. Some behavioral disturbance is expected, but 
NMFS expects the disturbance to be localized and short-term.
    The notice of the proposed IHA (75 FR 28568, May 21, 2010) included 
a discussion of the effects of sounds from airguns on mysticetes, 
odontocetes, and pinnipeds, including tolerance, masking, behavioral 
disturbance, hearing impairment, and other non-auditory physical 
effects. Additional information on the behavioral reactions (or lack 
thereof) by all types of marine mammals to seismic vessels can be found 
in L-DEO's application and NMFS' EA. The notice of the proposed IHA 
also included a discussion of the potential effects of the multibeam 
echosounder (MBES) and the sub-bottom profiler (SBP). Because of the 
shape of the beams of these sources and their power, NMFS believes it 
unlikely that marine mammals will be exposed to either the MBES or the 
SBP at levels at or above those likely to cause harassment. Further, 
NMFS believes that the brief exposure of cetaceans to a few signals 
from the multi-beam bathymetric sonar system is not likely to result in 
the harassment of marine mammals.

Anticipated Effects on Marine Mammal Habitat

    A detailed discussion of the potential effects of this action on 
marine mammal habitat, including physiological and behavioral effects 
on marine fish and invertebrates was included in the proposed IHA (75 
FR 28568, May 21, 2010). Based on the discussion in the proposed IHA 
notice and the nature of the activities (limited duration), the 
authorized operations are not expected to result in any permanent 
impact on habitats used by marine mammals, including the food sources 
they use. The main impact associated with the activity will be 
temporarily elevated noise levels and the associated direct effects on 
marine mammals.

Mitigation

    In order to issue an incidental take authorization (ITA) under 
Section 101(a)(5)(D) of the MMPA, NMFS must set forth the permissible 
methods of taking pursuant to such activity, and other means of 
effecting the least practicable adverse impact on such species or stock 
and its habitat, paying particular attention to rookeries, mating 
grounds, and areas of similar significance, and the availability of 
such species or stock for taking for certain subsistence uses.
    L-DEO has based the mitigation measures described herein, to be 
implemented for the seismic survey, on the following:
    (1) Protocols used during previous L-DEO seismic research cruises 
as approved by NMFS;
    (2) previous IHA applications and IHAs approved and authorized by 
NMFS; and
    (3) recommended best practices in Richardson et al. (1995), Pierson 
et al. (1998), and Weir and Dolman, (2007).
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, L-DEO and/or its designees will 
implement the following mitigation measures for marine mammals:
    (1) Exclusion zones;
    (2) power-down procedures;
    (3) shutdown procedures, including procedures for species of 
concern such as emergency shut-down procedures for North Pacific right 
whales; and
    (4) ramp-up procedures.
    Exclusion Zones-During the study, all survey effort will take place 
in deep (greater than 1,000 m) water. L-DEO

[[Page 44775]]

uses safety radii to designate exclusion zones and to estimate take 
(described in greater detail in Section VII of the application) for 
marine mammals. Table 1 shows the distances at which three sound levels 
(160-, 180-, and 190-dB) are expected to be received from the 36-airgun 
array and a single airgun. The 180- and 190-dB levels are shut-down 
criteria applicable to cetaceans and pinnipeds, respectively, as 
specified by NMFS (2000); and L-DEO used these levels to establish the 
EZs.

  Table 1--Measured (Array) or Predicted (Single Airgun) Distances to Which Sound Levels >=190, 180, and 160 dB
  re: 1 [mu]Pa Could be Received in Deep (>1000 m; 3280 ft) Water From the 36-Airgun Array, as Well as a Single
Airgun, During the Shatsky Rise Seismic Survey, July--September, 2010 (Based on L-DEO Models and Tolstoy et al.,
                                                     2009).
----------------------------------------------------------------------------------------------------------------
                                                                                   Predicted RMS Distances (m)
                      Source and volume                         Tow depth (m)   --------------------------------
                                                                                   190 dB     180 dB     160 dB
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun 40 in \3\................................              *9-12         12         40        385
4 Strings 36 airguns 6,600 in \3\...........................                  9        400        940      3,850
                                                                             12        460      1,100      4,400
----------------------------------------------------------------------------------------------------------------
*The tow depth has minimal effect on the maximum near-field output and the shape of the frequency spectrum for
  the single 40-in \3\ airgun; thus the predicted safety radii are essentially the same at each tow depth.

    If the protected species visual observer (PSVO) detects marine 
mammal(s) within or about to enter the appropriate EZ, the Langseth 
crew will immediately power down the airguns, or perform a shut down 
immediately (see Shut-down Procedures).
    Power-Down Procedures--A power down involves decreasing the number 
of airguns in use such that the radius of the 180-dB zone is decreased 
to the extent that marine mammals are no longer in or about to enter 
the EZ. A power down of the airgun array can also occur when the vessel 
is moving from one seismic line to another. During a power down for 
mitigation, L-DEO will operate one airgun. The continued operation of 
one airgun is intended to alert marine mammals to the presence of the 
seismic vessel in the area. In contrast, a shut down occurs when the 
Langseth suspends all airgun activity.
    If the PSVO detects a marine mammal (other than a north Pacific 
right whale--see Shut-down Procedures) outside the EZ, but it is likely 
to enter the EZ, L-DEO will power down the airguns to a single airgun 
before the animal is within the EZ. Likewise, if a mammal is already 
within the EZ when first detected L-DEO will power down the airguns 
immediately. During a power down of the airgun array, L-DEO will also 
operate the 40-in\3\ airgun. If the PSVO detects a marine mammal within 
or near the smaller EZ around that single airgun (Table 1), L-DEO will 
shut down the airgun (see next Section).
    Following a power down, L-DEO will not resume airgun activity until 
the marine mammal has cleared the safety zone for the full array. L-DEO 
will consider the animal to have cleared the EZ if:
     A PSVO has visually observed the animal leave the EZ, or
     a PSVO has not sighted the animal within the EZ for 15 
minutes. for small odontocetes (or pinnipeds), or 30 min. for 
mysticetes and large odontocetes, including sperm, pygmy sperm, dwarf 
sperm, and beaked whales.
    During airgun operations following a power down (or shut down) 
whose duration has exceeded the time limits specified previously, L-DEO 
will ramp-up the airgun array gradually (see Shut-down Procedures).
    Shut-down Procedures--L-DEO will shut down the operating airgun(s) 
if a marine mammal is seen within or approaching the EZ for the single 
airgun. L-DEO will implement a shut down:
    (1) If an animal enters the EZ of the single airgun after L-DEO has 
initiated a power down, or
    (2) If an animal is initially seen within the EZ of the single 
airgun when more than one airgun (typically the full airgun array) is 
operating. L-DEO will not resume airgun activity until the marine 
mammal has cleared the EZ, or until the PSVO is confident that the 
animal has left the vicinity of the vessel. Criteria for judging that 
the animal has cleared the EZ will be as described in the preceding 
section.
    Considering the conservation status for North Pacific right whales, 
L-DEO will shut down the airgun(s) immediately in the unlikely event 
that this species is observed, regardless of the distance from the 
Langseth. L-DEO will only begin a ramp-up if the right whale has not 
been seen for 30 minutes.
    Ramp-Up Procedures--L-DEO will follow a ramp-up procedure when the 
airgun array begins operating after a specified period without airgun 
operations or when a power down has exceeded that period. L-DEO 
proposes that, for the present cruise, this period would be 
approximately 8 minutes. This period is based on the 180-dB radius (940 
m, 3,084 ft) for the 36-airgun array towed at a depth of 9 m relation 
to the minimum planned speed of the Langseth while shooting (7.4 km/h, 
4.6 mi/h). Similar periods (approximately 8-10 minutes) were used 
during previous L-DEO surveys.
    Ramp-up will begin with the smallest airgun in the array (40-in 
\3\). Airguns will be added in a sequence such that the source level of 
the array will increase in steps not exceeding six dB per five-minute 
period over a total duration of approximately 35 minutes. During ramp-
up, the PSVOs will monitor the EZ, and if marine mammals are sighted, 
L-DEO will implement a power down or shut down as though the full 
airgun array were operational.
    If the complete EZ has not been visible for at least 30 minutes 
prior to the start of operations in either daylight or nighttime, L-DEO 
will not commence the ramp-up unless at least one airgun (40-in \3\ or 
similar) has been operating during the interruption of seismic survey 
operations. Given these provisions, it is likely that the airgun array 
will not be ramped up from a complete shut down at night or in thick 
fog, because the outer part of the safety zone for that array will not 
be visible during those conditions. If one airgun has operated during a 
power-down period, ramp-up to full power will be permissible at night 
or in poor visibility, on the assumption that marine mammals will be 
alerted to the approaching seismic vessel by the sounds from the single 
airgun and could move away. L-DEO will not initiate a ramp-up of the 
airguns if a marine mammal is sighted within or near the applicable EZs 
during the day or close to the vessel at night.

[[Page 44776]]

    NMFS has carefully evaluated the applicant's 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. Our 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 our evaluation of the applicant's mitigation measures, as 
well as other measures considered by NMFS or recommended by the public, 
NMFS has determined that the required mitigation measures provide the 
means of effecting the least practicable adverse impacts on marine 
mammals species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

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.
    L-DEO proposes to sponsor marine mammal monitoring during the 
present project, in order to implement the mitigation measures that 
require real-time monitoring, and to satisfy the anticipated monitoring 
requirements of the IHA. L-DEO's Monitoring Plan is described below 
this section and was planned as a self-contained project independent of 
any other related monitoring projects that may be occurring 
simultaneously in the same regions. L-DEO is prepared to discuss 
coordination of its monitoring program with any related work that might 
be done by other groups insofar as this is practical.

Vessel-based Visual Monitoring

    PSVOs will be based aboard the seismic source vessel and will watch 
for marine mammals near the vessel during daytime airgun operations and 
during any start-ups at night. PSVOs will also watch for marine mammals 
near the seismic vessel for at least 30 minutes prior to the start of 
airgun operations after an extended shut down. When feasible, PSVOs 
will also observe during daytime periods when the seismic system is not 
operating for comparison of sighting rates and behavior with airgun 
operations versus without airgun operations. Based on PSVO 
observations, L-DEO will power down or shut down the airguns when 
marine mammals are observed within a designated EZ or are 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 at the Shatsky Rise, five PSVOs will be 
based aboard the Langseth. L-DEO will appoint the PSVOs with NMFS' 
concurrence. At least one PSVO and when practical, two PSVOs will 
monitor marine mammals near the seismic vessel during ongoing daytime 
operations and nighttime start ups of the airguns. Use of two 
simultaneous PSVOs will increase the effectiveness of detecting animals 
near the sound source. PSVOs will be on duty in shifts of duration no 
longer than four hours. L-DEO will also instruct other vessel crew to 
assist in detecting marine mammals and implementing mitigation 
requirements (if practical). Before the start of the seismic survey, L-
DEO will give the crew additional instruction regarding how to 
accomplish this task.
    The Langseth is a suitable platform for marine mammal and turtle 
observations. When stationed on the observation platform, the eye level 
will be approximately 21.5 m (70.5 ft) above sea level, and the 
observer will have a good view around the entire vessel. During 
daytime, the PSVOs will scan the area around the vessel systematically 
with reticle binoculars (e.g., 7 x 50 Fujinon), Big-eye binoculars (25 
x 150), and with the naked eye. During darkness, night vision devices 
(NVDs) will be available (ITT F500 Series Generation 3 binocular-image 
intensifier or equivalent), when required. Laser range-finding 
binoculars (Leica LRF 1200 laser rangefinder or equivalent) will be 
available to assist with distance estimation. These devices are useful 
in training PSVOs to estimate distances visually, but are generally not 
useful in measuring distances to animals directly; that is done 
primarily with the reticles in the binoculars' lenses.

Passive Acoustic Monitoring

    Passive Acoustic Monitoring (PAM) will complement the visual 
monitoring program, when practicable. Visual monitoring typically is 
not effective during periods of poor visibility (e.g., bad weather) or 
at night. In instances of with good visibility, visual monitoring is 
unable to detect marine mammals when they are below the surface or 
beyond visual range. L-DEO can use acoustical monitoring in addition to 
visual observations to improve detection, identification, and 
localization of cetaceans. The acoustic monitoring will serve to alert 
visual observers (if on duty) when vocalizing cetaceans are detected. 
It is only useful when marine mammals call, but it can be effective 
either by day or by night, and does not depend on good visibility. It 
will be monitored in real time so that the visual observers can be 
advised when cetaceans are detected. When bearings (primary and mirror-
image) to calling cetacean(s) are determined, the bearings will be 
relayed to the visual observer to help him/her sight the calling 
animal(s).
    The PAM system consists of hardware (i.e., hydrophones) and 
software. The ``wet end'' of the system consists of a towed four-
hydrophone array, two of which are monitored simultaneously; the active 
section of the array is approximately 30 m (98 ft) long. The array is 
attached to the vessel by a 250-m (820 ft) electromechanical lead-in 
cable and a 50-m (164 ft) long deck lead-in cable. However, not the 
entire length of lead-in cable is used; thus, the hydrophones are 
typically located 120 m (394 ft) behind the stern of the ship. The deck 
cable is connected from the array to a computer in the laboratory where 
signal conditioning and processing takes place. The digitized signal is 
then sent to the main laboratory, where the acoustic PSVO monitors the 
system. The hydrophone array is typically towed at depths less than 20 
m (66 ft).
    The towed hydrophones will ideally be monitored 24 hr/d while at 
the seismic survey area during airgun operations, and during most 
periods when the Langseth is underway while the airguns are not 
operating. One PSVO will monitor the acoustic detection system at any 
one time, by listening to the signals from two channels via headphones 
and/or speakers and watching the real-time spectrographic display for 
frequency ranges produced by cetaceans. PSVOs monitoring the acoustical 
data will be on shift for one

[[Page 44777]]

to six hours at a time. Besides the PSVO, an additional protected 
species observer (PSO) with primary responsibility for PAM will also be 
aboard. All PSVOs are expected to rotate through the PAM position, 
although the most experienced with acoustics will be on PAM duty more 
frequently.
    When a vocalization is detected while visual observations are in 
progress, the acoustic PSO will contact the visual PSVO immediately, to 
alert him/her to the presence of cetaceans (if not already visually 
detected), and initiate a power down or shut down, if required. The 
information regarding the call will be entered into a database. The 
data to be entered include an acoustic encounter identification number, 
whether it was linked with a visual sighting, date, time when first and 
last heard and whenever any additional information was recorded, 
position and water depth when first detected, bearing if determinable, 
species or species group (e.g., unidentified dolphin, sperm whale), 
types and nature of sounds heard (e.g., clicks, continuous, sporadic, 
whistles, creaks, burst pulses, strength of signal, etc.), and any 
other notable information. The acoustic detection can also be recorded 
for further analysis.

PSVO Data and Documentation

    PSVOs will record data to estimate the numbers of marine mammals 
exposed to various received sound levels and to document apparent 
disturbance reactions or lack thereof. Data will be used to estimate 
numbers of animals potentially `taken' by harassment (as defined in the 
MMPA). They will also provide information needed to order a power down 
or shut down of the airguns when a marine mammal is within or near the 
EZ.
    When a sighting is made, the PSVO/L-DEO will record the following 
information about the sighting:
    1. Species, group size, age/size/sex categories (if determinable), 
behavior when first sighted and after initial sighting, heading (if 
consistent), bearing and distance from seismic vessel, sighting cue, 
apparent reaction to the airguns or vessel (e.g., none, avoidance, 
approach, paralleling, etc.), and behavioral pace.
    2. Time, location, heading, speed, activity of the vessel, sea 
state, visibility, and sun glare.
    The data listed under (2) will also be recorded at the start and 
end of each observation watch, and during a watch whenever there is a 
change in one or more of the variables.
    All observations and power downs or shut downs will be recorded in 
a standardized format. Data will be entered into an electronic 
database. The accuracy of the data entry will be verified by 
computerized data validity checks as the data are entered and by 
subsequent manual checking of the database. These procedures will allow 
initial summaries of data to be prepared during and shortly after the 
field program, and will facilitate transfer of the data to statistical, 
graphical, and other programs for further processing and archiving.
    Results from the vessel-based observations will provide:
    1. The basis for real-time mitigation (airgun power down or shut 
down).
    2. Information needed to estimate the number of marine mammals 
potentially taken by harassment, which must be reported to NMFS.
    3. Data on the occurrence, distribution, and activities of marine 
mammals and turtles in the area where the seismic study is conducted.
    4. Information to compare the distance and distribution of marine 
mammals and turtles relative to the source vessel at times with and 
without seismic activity.
    5. Data on the behavior and movement patterns of marine mammals and 
turtles seen at times with and without seismic activity.
    L-DEO will submit a report to NMFS and NSF within 90 days after the 
end of the cruise. The report will describe the operations conducted 
and sightings of marine mammals and turtles near the operations. The 
report will provide full documentation of methods, results, and 
interpretation pertaining to all monitoring. The 90-day report will 
summarize the dates and locations of seismic operations, and all marine 
mammal sightings (dates, times, locations, activities, associated 
seismic survey activities). The report will also include estimates of 
the number and nature of exposures that could result in ``takes'' of 
marine mammals by harassment or in other ways.
    L-DEO will report all injured or dead marine mammals (regardless of 
cause) to NMFS as soon as practicable. The report should include the 
species or description of the animal, the condition of the animal, 
location, time first found, observed behaviors (if alive) and photo or 
video, if available.

Estimated Take of Marine Mammals 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 authorized as a 
result of the marine geophysical survey at the Shatsky Rise. 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 decibels (dB) or cause temporary, short-term changes in 
behavior. There is no evidence that the activities could result in 
injury or mortality within the specified geographic area for which L-
DEO seeks the IHA. The required mitigation and monitoring measures are 
expected to minimize the possibility of takes by (Level A harassment), 
serious injury, or mortality.
    NMFS included an in-depth discussion of the methods used to 
calculate the densities of the marine mammals in the area of the 
seismic survey in a previous notice for the proposed IHA (75 FR 28568, 
May 21, 2010). A summary is included here.
    L-DEO's estimates are based on a consideration of the number of 
marine mammals that could be disturbed appreciably by operations with 
the 36-airgun array to be used during approximately 3,160 km of seismic 
surveys at the Shatsky Rise.
    Density data on 18 marine mammal species in the Shatsky Rise area 
are available from two sources using conventional line transect 
methods: Japanese sighting surveys conducted since the early 1980s, and 
fisheries observers in the high-seas driftnet fisheries during 1987-
1990 (see Table 3 in L-DEO's application). For the 16 other marine 
mammal species that could be encountered in the survey area, data from 
the western North Pacific right whale are not available (see Table 3 in 
L-DEO's application). NMFS is not aware of any density estimates for 
three of those species--Hubb's, Stejneger's, and gingko-toothed beaked 
whales. For the remaining 13 species (see Table 3 in L-DEO's 
application), density estimates are available from other areas of the 
Pacific: 11 species from the offshore stratum of the 2002 Hawaiian 
Islands survey (Barlow, 2006) and two species from surveys of the 
California Current ecosystem off the U.S. west coast between 1991 and 
2005 (Barlow and Forney, 2007). Those estimates are based on standard 
line-transect protocols developed by NMFS'

[[Page 44778]]

Southwest Fisheries Science Center (SWFSC).
    Densities for 14 species are available from Japanese sighting 
surveys in the Shatsky Rise survey area. Miyashita (1993a) provided 
estimates for six dolphin species in this area that have been taken in 
the Japanese drive fisheries. The densities used here are Miyashita's 
(1993a) estimates for the `Eastern offshore' survey area (30-42[deg] N, 
145[deg]-180[deg] E). Kato and Miyashita (1998) provided estimates for 
sperm whale densities from Japanese sightings data during 1982 to 1996 
in the western North Pacific (20-50[deg] N, 130[deg]-180[deg] E), and 
Hakamada et al. (2004) provided density estimates for sei whales during 
August through September in the JARPN II sub-areas 8 and 9 (35-50[deg] 
N, 150-170[deg] E excluding waters in the Exclusive Economic Zone of 
Russia) during 2002 and 2003. L-DEO used density estimates during 1994 
through 2007 for minke whales at 35-40[deg] N, 157-170[deg] E from 
Hakamada et al. (2009), density estimates during 1998 through 2002 for 
Bryde's whales at 31-43[deg] N, 145-165[deg] E from Kitakado et al. 
(2008), and density estimates during 1994-2007 for blue, fin, humpback, 
and North Pacific right whales at 31-51[deg] N, 140-170[deg] E from 
Matsuoka et al. (2009).
    For four species (northern fur seal, Dall's porpoise, Pacific 
white-sided dolphin (Lagenorhynchus obliquidens), northern right-whale 
dolphin (Lissodelphis borealis)), estimates of densities in the Shatsky 
Rise area are available from sightings data collected by observers in 
the high-seas driftnet fisheries during 1987 through 1990 (Buckland et 
al., 1993). Those data were analyzed for 5[deg] x 5[deg] blocks, and 
the densities used here are from blocks for which available data 
overlap the survey area. In general, those data represent the average 
annual density in the northern half of the Shatsky Rise survey area 
(35-40[deg] N).
    The densities mentioned above had been corrected by the original 
authors for detectability bias and, with the exception of Kitakado et 
al. (2008) and Hakamada et al. (2009), for availability bias. 
Detectability bias is associated with diminishing sightability with 
increasing lateral distance from the track line [f(0)]. Availability 
bias refers to the fact that there is less than a 100 percent 
probability of sighting an animal that is present along the survey 
track line, and it is measured by g(0).
    There is some uncertainty about the accuracy of the density data 
from the Japanese Whale Research Program under Special Permit (JARPN/
JARPN II). For example, densities in Miyashita (1993a) and Buckland et 
al. (1993) are from the 1980s and represent the best available 
information for the Shatsky Rise area at this time. To provide some 
allowance for these uncertainties, particularly underestimates of 
densities present and numbers of marine mammals potentially affected 
have been derived; L-DEO's maximum estimates (precautionary estimates) 
are 1.5 times greater than the best estimates.
    The estimated numbers of individuals potentially exposed are based 
on the 160-dB re 1 [mu]Pa [middot] mrms criterion for all 
cetaceans (see Table 2 in this notice). It is assumed that marine 
mammals exposed to airgun sounds that strong might change their 
behavior sufficiently to be considered ``taken by harassment.''
    L-DEO's estimates of exposures to various sound levels assume that 
the surveys will be completed. 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 exclusion zones will 
result in the power down or shut down of seismic operations as a 
mitigation measure. Thus, the following estimates of the numbers of 
marine mammals potentially exposed to sound levels of 160 re 1 [mu]Pa 
[middot] mrms 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.
    Table 2 in this notice shows the best and maximum estimated number 
of exposures and the number of different individuals potentially 
exposed during the seismic survey if no animals moved away from the 
survey vessel. The take authorization is based on the maximum estimates 
in Table 2 rather than the best estimates of the numbers of individuals 
exposed, because of uncertainties associated with applying density data 
from one area to another.
    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 
[middot] mrms on one or more occasions was estimated by 
considering the total marine area that would be within the 160-dB 
radius around the operating airgun array on at least one occasion. The 
number of possible exposures (including repeated exposures of the same 
individuals) can be estimated by considering the total marine area that 
would be within the 160-dB radius around the operating airguns, 
including areas of overlap. In the survey, the seismic lines are widely 
spaced in the survey area, so an individual mammal would most likely 
not be exposed numerous times during the survey; the area including 
overlap is only 1.4 times the area excluding overlap. Moreover, it is 
unlikely that a particular animal would stay in the area during the 
entire survey. The number of different individuals potentially exposed 
to received levels greater than or equal to 160 re 1 [mu]Pa [middot] 
mrms was calculated by multiplying:
    (1) The expected species density, either ``mean'' (i.e., best 
estimate) or ``maximum'', times
    (2) the anticipated minimum area to be ensonified to that level 
during airgun operations including overlap (exposures), or
    (3) the anticipated area to be ensonified to that level during 
airgun operations excluding overlap (individuals).
    The area expected to be ensonified was determined by entering the 
planned survey lines into a MapInfo Geographic Information System 
(GIS), using the GIS to identify the relevant areas by ``drawing'' the 
applicable 160-dB buffer (see Table 1) around each seismic line, and 
then calculating the total area within the buffers. Areas of overlap 
were included only once when estimating the number of individuals 
exposed.
    Applying the approach described above, approximately 20,831 square 
kilometers (km\2\) would be within the 160-dB isopleth on one or more 
occasions during the survey, whereas 22,614 km\2\ is the area 
ensonified to greater than or equal to 160 dB when overlap is included. 
Thus, an average individual marine mammal would be exposed only once 
during the survey. Because this approach does not allow for turnover in 
the mammal populations in the study area during the course of the 
survey, the actual number of individuals exposed could be 
underestimated. However, the approach assumes that no cetaceans will 
move away from or toward the trackline as the Langseth approaches in 
response to increasing sound levels prior to the time the levels reach 
160 dB, which will result in overestimates for those species known to 
avoid seismic vessels.
    The `maximum estimate' of the number of individual cetaceans that 
could be exposed to seismic sounds with received levels greater than or 
equal to 160 dB re: 1 [mu]Pa during the survey is 20,003. Most (96%) of 
the cetaceans potentially exposed are delphinids; short-beaked common, 
striped, pantropical spotted, and Pacific white-sided dolphins are 
estimated to be the most common species in the area,

[[Page 44779]]

with maximum estimates of 9,666 (0.3% of the regional population), 
3,721 (0.7%), 2,200 (0.5%), and 1,137 (0.1%) exposed to levels greater 
than or equal to 160 dB re: 1 [mu]Pa, respectively.

  Table 2--Estimates of the Possible Numbers of Marine Mammals Exposed To Different Sound Levels During L-DEO's
                          Seismic Survey at Shatsky Rise During July--September, 2010.
----------------------------------------------------------------------------------------------------------------
                                                           Estimated number of           Estimated number of
                                                      individuals exposed to sound  individuals exposed to sound
                       Species                           levels >= 160 dB re: 1        levels >= 160 dB re: 1
                                                              [mu]Pa (Best)               [mu]Pa (Maximum)
----------------------------------------------------------------------------------------------------------------
North Pacific right whale...........................                            1                             2
Humpback whale......................................                           15                            22
Minke whale.........................................                           57                            85
Bryde's whale.......................................                           11                            16
Sei whale...........................................                           37                            56
Fin whale...........................................                           22                            34
Blue whale..........................................                           12                            18
Sperm whale.........................................                           22                            32
Pygmy sperm whale...................................                           66                           100
Dwarf sperm whale...................................                          163                           244
Cuvier's beaked whale...............................                          142                           212
Baird's beaked whale................................                           18                            27
Longman's beaked whale..............................                            9                            14
Blainville's beaked whale...........................                           27                            40
Mesoplodon spp......................................                            2                             3
Rough-toothed dolphin...............................                           65                            97
Bottlenose dolphin..................................                          500                           750
Pantropical spotted dolphin.........................                        1,467                         2,200
Spinner dolphin.....................................                           17                            26
Striped dolphin.....................................                        2,480                         3,721
Fraser's dolphin....................................                           95                           143
Short-beaked common dolphin.........................                        6,444                         9,666
Pacific white-sided dolphin.........................                          758                         1,137
Northern right whale dolphin........................                            9                            13
Risso's dolphin......