Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Geophysical Survey of the Queen Charlotte Fault, 30006-30034 [2021-11718]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 86, Number 106 (Friday, June 4, 2021)]
[Notices]
[Pages 30006-30034]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-11718]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XB083]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Geophysical Survey of the Queen 
Charlotte Fault

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

ACTION: Notice; proposed incidental harassment authorization; request 
for comments on proposed authorization and possible renewal.

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SUMMARY: NMFS has received a request from the Lamont-Doherty Earth 
Observatory of Columbia University (L-DEO) for authorization to take 
marine mammals incidental to a marine geophysical survey of the Queen 
Charlotte Fault in the Northeast Pacific Ocean. The proposed survey 
would be funded by the National Science Foundation (NSF). Pursuant to 
the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on 
its proposal to issue an incidental harassment authorization (IHA) to 
incidentally take marine mammals during the specified activities. NMFS 
is also requesting comments on a possible one-time, one-year renewal 
that could be issued under certain circumstances and if all 
requirements are met, as described in Request for Public Comments at 
the end of this notice. NMFS will consider public comments prior to 
making any final decision on the issuance of the requested MMPA 
authorizations and agency responses will be summarized in the final 
notice of our decision.

DATES: Comments and information must be received no later than July 6, 
2021.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Physical comments should be sent to 
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments 
should be sent to [email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments received electronically, including 
all attachments, must not exceed a 25-megabyte file size. All comments 
received are a part of the public record

[[Page 30007]]

and will generally be posted online at www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act 
without change. All personal identifying information (e.g., name, 
address) voluntarily submitted by the commenter may be publicly 
accessible. Do not submit confidential business information or 
otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT: Ben Laws, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these documents, please call the 
contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be provided to the public 
for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment.
    Accordingly, NMFS plans to adopt NSF's Environmental Assessment 
(EA), as we have preliminarily determined that it includes adequate 
information analyzing the effects on the human environment of issuing 
the IHA. NSF's EA is available at www.nsf.gov/geo/oce/envcomp/.
    We will review all comments submitted in response to this notice 
prior to concluding our NEPA process or making a final decision on the 
IHA request.

Summary of Request

    On December 3, 2019, NMFS received a request from L-DEO for an IHA 
to take marine mammals incidental to a geophysical survey of the Queen 
Charlotte Fault (QCF) off of Alaska and British Columbia, Canada. L-DEO 
submitted a revised version of the application on April 2, 2020. On 
April 10, 2020, L-DEO informed NMFS that the planned survey would be 
deferred to 2021 as a result of issues related to the COVID-19 
pandemic. L-DEO subsequently submitted revised versions of the 
application on October 22 and December 16, 2020, the latter of which 
was deemed adequate and complete. A final, revised version was 
submitted on January 11, 2021. L-DEO's request is for take of 21 
species of marine mammals by Level B harassment. In addition, NMFS 
proposes to authorize take by Level A harassment for seven of these 
species.

Description of Proposed Activity

Overview

    Researchers from L-DEO, the University of New Mexico, and Western 
Washington University, with funding from NSF, propose to conduct a 
high-energy seismic survey from the Research Vessel (R/V) Marcus G. 
Langseth (Langseth) at the QCF in the northeast Pacific Ocean during 
late summer 2021. Other research collaborators include Dalhousie 
University, the Geological Survey of Canada, and the U.S. Geological 
Survey. The proposed two-dimensional (2-D) seismic survey would occur 
within the Exclusive Economic Zones (EEZ) of the United States and 
Canada, including in Canadian territorial waters. The survey would use 
a 36-airgun towed array with a total discharge volume of ~6,600 cubic 
inches (in\3\) as an acoustic source, acquiring return signals using 
both a towed streamer as well as ocean bottom seismometers (OBSs).
    The proposed study would use 2-D seismic surveying to characterize 
crustal and uppermost mantle velocity structure, fault zone 
architecture and rheology, and seismicity of the QCF. The QCF system is 
an approximately 1,200 kilometer (km)-long onshore-offshore transform 
system connecting the Cascadia and Alaska-Aleutian subduction zones; 
the QCF is the approximately 900 km-long offshore component of the 
transform system. The purpose of the proposed study is to characterize 
an approximately 450-km segment of the fault that encompasses 
systematic variations in key parameters in space and time: (1) Changes 
in fault obliquity relative to Pacific-North American plate motion 
leading to increased convergence from north to south; (2) Pacific plate 
age and theoretical mechanical thickness decrease from north to south; 
and (3) a shift in Pacific plate motion at approximately 12-6 million 
years ago that may have increased convergence along the entire length 
of the fault, possibly initiating underthrusting in the southern 
portion of the study area. Current understanding of how these 
variations are expressed through seismicity, crustal-scale deformation, 
and lithospheric structure and dynamics is limited due to lack of 
instrumentation and modern seismic imaging.

Dates and Duration

    The proposed survey is expected to last for approximately 36 days, 
including approximately 27 days of seismic operations, 3 days of 
equipment deployment/retrieval, 2 days of transits, and 4 contingency 
days (accounting for potential delays due to, e.g., weather). R/V 
Langseth would likely leave out of and return to port in Ketchikan, 
Alaska, during July-August 2021.

Specific Geographic Region

    The proposed survey would occur within the area of approximately 
52-57[deg] N and approximately 131-137[deg] W. Representative survey 
tracklines are shown in Figure 1. Some deviation in actual track lines, 
including the order of survey operations, could be necessary for 
reasons such as science drivers, poor data quality, inclement weather, 
or mechanical issues with the research vessel and/or equipment. The 
survey is proposed to occur within the EEZs of the United States and 
Canada, including Alaskan state waters and Canadian territorial waters, 
ranging in depth from

[[Page 30008]]

50-2,800 meters (m). Approximately 4,250 km of transect lines would be 
surveyed, with 13 percent of the transect lines in Canadian territorial 
waters. Most of the survey (69 percent) would occur in deep water 
(>1,000 m), 30 percent would occur in intermediate water (100-1,000 m 
deep), and approximately 1 percent would take place in shallow water 
<100 m deep.
    Note that the MMPA does not apply in Canadian territorial waters. 
L-DEO is subject only to Canadian law in conducting that portion of the 
survey. However, NMFS has calculated the expected level of incidental 
take in the entire activity area (including Canadian territorial 
waters) as part of the analysis supporting our determination under the 
MMPA that the activity will have a negligible impact on the affected 
species (see Estimated Take and Negligible Impact Analysis and 
Determination).
BILLING CODE 3510-22-P

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[GRAPHIC] [TIFF OMITTED] TN04JN21.003

BILLING CODE 3510-22-C

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Detailed Description of Specific Activity

    The procedures to be used for the proposed survey would be similar 
to those used during previous seismic surveys by L-DEO and would use 
conventional seismic methodology. The surveys would involve one source 
vessel, the R/V Langseth. R/V Langseth would deploy an array of 36 
airguns as an energy source with a total volume of 6,600 in\3\. The 
array consists of 36 elements, including 20 Bolt 1500LL airguns with 
volumes of 180 to 360 in\3\ and 16 Bolt 1900LLX airguns with volumes of 
40 to 120 in\3\. The airgun array configuration is illustrated in 
Figure 2-11 of NSF and USGS's Programmatic Environmental Impact 
Statement (PEIS; NSF-USGS, 2011). (The PEIS is available online at: 
www.nsf.gov/geo/oce/envcomp/usgs-nsf-marine-seismic-research/nsf-usgs-final-eis-oeis-with-appendices.pdf). The vessel speed during seismic 
operations would be approximately 4.2 knots (kn) (~7.8 km/hour) during 
the survey and the airgun array would be towed at a depth of 12 m. The 
receiving system would consist of OBSs and a towed hydrophone streamer 
with a nominal length of 15 km (OBS and multi-channel seismic (MCS) 
shooting). As the airguns are towed along the survey lines, the 
hydrophone streamer would transfer the data to the on-board processing 
system, and the OBSs would receive and store the returning acoustic 
signals internally for later analysis.
    Approximately 60 short-period OBSs would be deployed and 
subsequently retrieved at a total of 123 sites in multiple phases from 
a second vessel, the Canadian Coast Guard ship John P. Tully (CCGS 
Tully). Along OBS refraction lines, OBSs would be deployed by CCGS 
Tully at 10 km intervals, with a spacing of 5 km over the central 40 km 
of the fault zone for fault-normal crossings. Twenty-eight broadband 
OBS instruments would also collect data during the survey and would be 
deployed prior to the active-source seismic survey, depending on 
logistical constraints. When an OBS is ready to be retrieved, an 
acoustic release transponder (pinger) interrogates the instrument at a 
frequency of 8-11 kHz; a response is received at 11.5-13 kHz. The burn-
wire release assembly is then activated, and the instrument is released 
from its 80-kg anchor to float to the surface. Take of marine mammals 
is not expected to occur incidental to L-DEO's use of OBSs.
    The airguns would fire at a shot interval of 50 m (approximately 23 
s) during MCS shooting with the hydrophone streamer (approximately 42 
percent of survey effort), at a 150-m interval (approximately 69 s) 
during refraction surveying to OBSs (approximately 29 percent of survey 
effort), and at a shot interval of every minute (approximately 130 m) 
during turns (approximately 29 percent of survey effort).
    Short-period OBSs would be deployed first along five OBS refraction 
lines by CCGS Tully. Two OBS lines run parallel to the coast, and three 
are perpendicular to the coast; one perpendicular line is located off 
Southeast Alaska, one is off Haida Gwaii, British Columbia, and another 
is located in Dixon Entrance. Please see Figure 1 for all location 
references. Following refraction shooting of a single line, short-
period instruments on that line would be recovered, serviced, and 
redeployed on a subsequent refraction line while MCS data would be 
acquired by the Langseth. MCS lines would be acquired off Southeast 
Alaska, Haida Gwaii, and Dixon Entrance. The coast-parallel OBS 
refraction transect nearest to shore would only be surveyed once at OBS 
shot spacing. The other coast-parallel OBS refraction transect (on the 
ocean side) would be acquired twice, once during refraction and once 
during reflection surveys. In addition, portions of the three coast-
perpendicular OBS refraction lines would also be surveyed twice, once 
for OBS shot spacing and once for MCS shot spacing. The coincident 
reflection/refraction profiles that run parallel to the coast would be 
acquired in multiple segments to ensure straight-line geometry. 
Sawtooth transits during which seismic data would be acquired would 
take place between transect lines when possible; otherwise, boxcar 
turns would be performed to save time. Both reflection and refraction 
surveys would use the same airgun array with the same discharge volume. 
There could be additional seismic operations associated with turns, 
airgun testing, and repeat coverage of any areas where initial data 
quality is sub-standard, and 25 percent has been added to the assumed 
survey line-kms to account for this potential.
    Note that the location of some tracklines has been modified from 
the original proposal as represented in Figure 1 and reflected in the 
take estimation analysis (see Estimated Take). However, these minor 
modifications do not substantively impact the location of survey effort 
or the proportion of survey effort in different depth bins and, 
therefore, the original take estimates remain accurate.
    In addition to the operations of the airgun array, a multibeam 
echosounder (MBES), a sub-bottom profiler (SBP), and an Acoustic 
Doppler Current Profiler (ADCP) would be operated from R/V Langseth 
continuously during the seismic surveys, but not during transit to and 
from the survey area. Take of marine mammals is not expected to occur 
incidental to use of the MBES, SBP, or ADCP because they will be 
operated only during seismic acquisition, and it is assumed that, 
during simultaneous operations of the airgun array and the other 
sources, any marine mammals close enough to be affected by the MBES, 
SBP, and ADCP would already be affected by the airguns. However, 
whether or not the airguns are operating simultaneously with the other 
sources, given the other sources' characteristics (e.g., narrow 
downward-directed beam), marine mammals would experience no more than 
one or two brief ping exposures from them, if any exposure were to 
occur. Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS' Stock Assessment Reports (SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and 
more general information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS' website 
(www.fisheries.noaa.gov/find-species).
    Table 1 lists all species with expected potential for occurrence in 
the survey area and summarizes information related to the population or 
stock, including regulatory status under the MMPA and Endangered 
Species Act (ESA) and potential biological removal (PBR), where known. 
For taxonomy, we follow Committee on Taxonomy (2020). PBR is defined by 
the MMPA as the maximum number of animals, not including natural 
mortalities, that may be removed from a marine mammal stock while 
allowing that stock to reach or maintain its optimum sustainable 
population (as described in NMFS's SARs). While no mortality is 
anticipated or authorized here, PBR and annual serious injury and 
mortality from anthropogenic sources are included here

[[Page 30011]]

as gross indicators of the status of the species and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Pacific and Alaska SARs. All MMPA stock information 
presented in Table 1 is the most recent available at the time of 
publication and is available in the 2019 SARs (Caretta et al., 2020; 
Muto et al., 2020) and draft 2020 SARs (available online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports). Where available, abundance and status 
information is also presented for marine mammals in British Columbia 
waters.
    Twenty-one species (with 28 managed stocks) are considered to have 
the potential to occur in the proposed survey area. Species that could 
potentially occur in the proposed research area but are not likely to 
be harassed due to the rarity of their occurrence (i.e., are considered 
extralimital or rare visitors to southeast Alaska/northern British 
Columbia) are described briefly but omitted from further analysis. 
These generally include species that do not normally occur in the area 
but for which there are one or more occurrence records that are 
considered beyond the normal range of the species. These species 
include pygmy sperm whale (Kogia breviceps), dwarf sperm whale (K. 
sima), Blainville's beaked whale (Mesoplodon densirostris), Hubbs' 
beaked whale (Mesoplodon carlhubbsi), false killer whale (Pseudorca 
crassidens), short-finned pilot whale (Globicephala macrorhynchus), 
common bottlenose dolphin (Tursiops truncatus), common dolphin 
(Delphius delphis), striped dolphin (Stenella coeruleoalba), and rough-
toothed dolphin (Steno bredanensis), which are all typically 
distributed further south in the California Current ecosystem, and 
beluga whales (Delphinapterus leucas), which are found further north, 
with a population in Yakutat Bay.
    The North Pacific right whale (Eubalaena japonica) historically 
occurred across the North Pacific Ocean in subpolar to temperate 
waters, including waters off the coast of British Columbia (Scarff, 
1986; Clapham et al., 2004). Sightings of this endangered species are 
now extremely rare, occurring primarily in the Okhotsk Sea and the 
eastern Bering Sea (Brownell et al., 2001; Shelden et al., 2005; Wade 
et al., 2006; Zerbini et al., 2010). In 2013, two North Pacific right 
whale sightings were made off the coast of British Columbia (U.S. 
Department of the Navy, 2015). There have also been four sightings, 
each of a single North Pacific right whale, in California waters within 
approximately the last 30 years (most recently in 2017) (Carretta et 
al., 1994; Brownell et al., 2001; Price, 2017). There is a very low 
probability of encountering this species in the action area, and it is 
not discussed further.
    There are eight killer whale stocks recognized in the U.S. Pacific, 
with Southern Resident killer whales being the only ESA-listed 
population. Southern Resident killer whales primarily occur in the 
southern Strait of Georgia, Strait of Juan de Fuca, Puget Sound, and 
the southern half of the west coast of Vancouver Island (Carretta et 
al., 2020). However, they have been observed in southeast Alaska. In 
2007, whales from L-pod were sighted off Chatham Strait, Alaska, the 
farthest north they have ever been documented (Carretta et al., 2020). 
During the summer, Southern Resident killer whales typically spend 
their time within the inland waters of Washington and southern British 
Columbia, south of the proposed survey area. There is a very low 
probability of encountering this stock in the action area, and it is 
not discussed further.
    In addition, the northern sea otter (Enhydra lutris kenyoni) is 
found in coastal waters of Alaska. However, this species is managed by 
the U.S. Fish and Wildlife Service and is not considered further in 
this document.

                                               Table 1--Marine Mammals That Could Occur in the Survey Area
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                                                                                  ESA/ MMPA      Stock abundance
                                                                                   status;       (CV, Nmin, most        British                Annual M/
           Common name                Scientific name            Stock          strategic (Y/    recent abundance      Columbia        PBR       SI \4\
                                                                                   N) \1\          survey) \2\       abundance \3\
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family Eschrichtiidae: Gray whale  Eschrichtius          Eastern North         -; N            26,960 (0.05;        ..............        801        131
                                    robustus.             Pacific (ENP) *.                      25,849; 2016).
                                                         Western North         E/D; Y          290 (n/a; 271;       ..............       0.12        Unk
                                                          Pacific (WNP) *.                      2016).
Family Balaenopteridae
 (rorquals):
    Humpback whale...............  Megaptera             Central North         E/D; Y          10,103 (0.3; 7,891;           1,029         83         26
                                    novaeangliae kuzira.  Pacific (CNP) *.                      2006).
    Minke whale..................  Balaenoptera          Alaska *............  -; N            Unknown............             522     Undet.          0
                                    acutorostrata
                                    scammoni.
    Sei whale....................  B. borealis borealis  ENP.................  E/D; Y          519 (0.4; 374;       ..............       0.75      >=0.2
                                                                                                2014).
    Fin whale....................  B. physalus physalus  Northeast Pacific *.  E/D; Y          Unknown............             329     Undet.        0.6
    Blue whale...................  B. musculus musculus  ENP.................  E/D; Y          1,496 (0.44; 1,050;  ..............     \7\1.2     >=19.4
                                                                                                2014).
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                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family Physeteridae: Sperm whale   Physeter              North Pacific *.....  E/D; Y          Unknown............  ..............     Undet.        3.5
                                    macrocephalus.
Family Ziphiidae (beaked whales):
    Cuvier's beaked whale........  Ziphius cavirostris.  Alaska *............  -; N            Unknown............  ..............     Undet.          0
    Baird's beaked whale.........  Berardius bairdii...  Alaska *............  -; N            Unknown............  ..............     Undet.          0
    Stejneger's beaked whale.....  Mesoplodon            Alaska *............  -; N            Unknown............  ..............     Undet.          0
                                    stejnegeri.
Family Delphinidae:

[[Page 30012]]

 
    Pacific white-sided dolphin..  Lagenorhynchus        North Pacific \6\...  -; N            26,880 (n/a;                 22,160     Undet.          0
                                    obliquidens.                                                26,880; 1990).
    Northern right whale dolphin.  Lissodelphis          CA/OR/WA............  -; N            26,556 (0.44;        ..............        179        3.8
                                    borealis.                                                   18,608; 2014).
    Risso's dolphin..............  Grampus griseus.....  CA/OR/WA............  -; N            6,336 (0.32; 4,817;  ..............         46      >=3.7
                                                                                                2014).
    Killer whale.................  Orcinus orca \5\....  ENP Offshore........  -; N            300 (0.1; 276;                  371        2.8          0
                                                                                                2012).
                                                         ENP Gulf of Alaska,   -; N            587 (n/a; 2012)....                        5.9        0.8
                                                          Aleutian Islands,
                                                          and Bering Sea
                                                          Transient.
                                                         ENP West Coast        -; N            349 (n/a; 2018)....                        3.5        0.4
                                                          Transient.
                                                         ENP Alaska Resident.  -; N            2,347 (n/a; 2012)..                         24          1
                                                         Northern Resident...  -; N            302 (n/a; 2018)....                        2.2        0.2
Family Phocoenidae (porpoises):
    Harbor porpoise..............  Phocoena phocoena     Southeast Alaska *..  -; Y            Unknown............           8,091     Undet.         34
                                    vomerina.
    Dall's porpoise..............  Phocoenoides dalli    Alaska \6\..........  -; N            83,400 (0.097; n/a;           5,303     Undet.         38
                                    dalli.                                                      1991).
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                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Northern fur seal............  Callorhinus ursinus.  Pribilof Islands/     D; Y            608,143 (0.2;        ..............     11,067        387
                                                          Eastern Pacific.                      514,738; 2018).
    California sea lion..........  Zalophus              United States.......  -/-; N          257,606 (N/A,        ..............     14,011      >=321
                                    californianus.                                              233,515, 2014).
    Steller sea lion.............  Eumetopias jubatus    Western U.S. *......  E/D; Y          52,932 (n/a; 2019).          15,348        318        255
                                    jubatus.
                                   E. j. monteriensis..  Eastern U.S. *......  -/-; N          43,201 (n/a; 2017).                      2,592        112
Family Phocidae (earless seals):
    Harbor seal..................  Phoca vitulina        Sitka/Chatham Strait  -; N            13,289 (n/a;                 24,916        356         77
                                    richardii.                                                  11,883; 2015).
                                                         Dixon/Cape Decision.  -; N            23,478 (n/a;                               644         69
                                                                                                21,453; 2015).
                                                         Clarence Strait.....  -; N            27,659 (n/a;                               746         40
                                                                                                24,854; 2015).
    Northern elephant seal.......  Mirounga              California Breeding.  -; N            179,000 (n/a;        ..............      4,882        8.8
                                    angustirostris.                                             81,368; 2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Stocks marked with an asterisk are addressed in further detail in text below.
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is
  coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For most stocks of killer whales, the
  abundance values represent direct counts of individually identifiable animals; therefore there is only a single abundance estimate with no associated
  CV. For certain stocks of pinnipeds, abundance estimates are based upon observations of animals (often pups) ashore multiplied by some correction
  factor derived from knowledge of the species' (or similar species') life history to arrive at a best abundance estimate; therefore, there is no
  associated CV. In these cases, the minimum abundance may represent actual counts of all animals ashore.
\3\ Total abundance estimates for animals in British Columbia based on surveys of the Strait of Georgia, Johnstone Strait, Queen Charlotte Sound, Hecate
  Strait, and Dixon Entrance. This column represents estimated abundance of animals in British Columbia, where available, but does not necessarily
  represent additional stocks. Please see Best et al. (2015) and Pitcher et al. (2007) for additional information.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, subsistence hunting, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum
  value. All M/SI values are as presented in the draft 2020 SARs.
\5\ Transient and resident killer whales are considered unnamed subspecies (Committee on Taxonomy, 2020).
\6\ Abundance estimates for these stocks are not considered current. PBR is therefore considered undetermined for these stocks, as there is no current
  minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as these represent the best available
  information for use in this document.
\7\ This stock is known to spend a portion of time outside the U.S. EEZ. Therefore, the PBR presented here is the allocation for U.S. waters only and is
  a portion of the total. The total PBR for blue whales is 2.1 (7/12 allocation for U.S. waters). Annual M/SI presented for these species is for U.S.
  waters only.

    Table 1 denotes the status of species and stocks under the U.S. 
MMPA and ESA. We note also that under Canada's Species at Risk Act, the 
sei whale and blue whale are listed as endangered; the fin whale and 
northern resident, offshore, and transient populations of killer whales 
are listed as threatened; and the humpback whale, harbor porpoise, and 
Steller sea lion are considered species of special concern.
    Two populations of gray whales are recognized, eastern and western 
North Pacific (ENP and WNP). WNP whales are known to feed in the 
Okhotsk Sea and off of Kamchatka before migrating south to poorly known 
wintering grounds, possibly in the South China Sea. The two populations 
have historically been considered geographically isolated from each 
other; however, data from satellite-tracked whales indicate that there 
is some overlap between the stocks. Two WNP whales were tracked from 
Russian foraging areas along the Pacific rim to Baja California (Mate 
et al., 2011), and, in one case where the satellite tag remained 
attached to the whale for a

[[Page 30013]]

longer period, a WNP whale was tracked from Russia to Mexico and back 
again (IWC, 2012). A number of whales are known to have occurred in the 
eastern Pacific through comparisons of ENP and WNP photo-identification 
catalogs (IWC, 2012; Weller et al., 2011; Burdin et al., 2011). 
Therefore, a portion of the WNP population is assumed to migrate, at 
least in some years, to the eastern Pacific during the winter breeding 
season. Based on guidance provided through interagency consultation 
under section 7 of the ESA, approximately 0.1 percent of gray whales 
occurring in southeast Alaska and northern British Columbia are likely 
to be from the Western North Pacific stock; the rest would be from the 
Eastern North Pacific stock.
    Prior to 2016, humpback whales were listed under the ESA as an 
endangered species worldwide. Following a 2015 global status review 
(Bettridge et al., 2015), NMFS delineated 14 distinct population 
segments (DPS) with different listing statuses (81 FR 62259; September 
8, 2016) pursuant to the ESA. The DPSs that occur in U.S. waters do not 
necessarily equate to the existing stocks designated under the MMPA and 
shown in Table 1.
    In the eastern North Pacific, three humpback whale DPSs may occur: 
The Hawaii DPS (not listed), Mexico DPS (threatened), and Central 
America DPS (endangered). Individuals encountered in the proposed 
survey area would likely be from the Hawaii DPS, followed by the Mexico 
DPS; individuals from the Central America DPS are unlikely to feed in 
northern British Columbia and Southeast Alaska (Ford et al., 2014). 
According to Wade (2017), in southeast Alaska and northern British 
Columbia, encountered whales are most likely to be from the Hawaii DPS 
(96.1 percent), but could be from the Mexico DPS (3.8 percent).
    Although no comprehensive abundance estimate is available for the 
Alaska stock of minke whales, recent surveys provide estimates for 
portions of the stock's range. A 2010 survey conducted on the eastern 
Bering Sea shelf produced a provisional abundance estimate of 2,020 (CV 
= 0.73) whales (Friday et al., 2013). This estimate is considered 
provisional because it has not been corrected for animals missed on the 
trackline, animals submerged when the ship passed, or responsive 
movement. Additionally, line-transect surveys were conducted in shelf 
and nearshore waters (within 30-45 nautical miles of land) in 2001-2003 
between the Kenai Peninsula (150[deg] W) and Amchitka Pass (178[deg] 
W). Minke whale abundance was estimated to be 1,233 (CV = 0.34) for 
this area (also not been corrected for animals missed on the trackline) 
(Zerbini et al., 2006). The majority of the sightings were in the 
Aleutian Islands, rather than in the Gulf of Alaska, and in water 
shallower than 200 m. These estimates cannot be used as an estimate of 
the entire Alaska stock of minke whales because only a portion of the 
stock's range was surveyed. Similarly, although a comprehensive 
abundance estimate is not available for the northeast Pacific stock of 
fin whales, provisional estimates representing portions of the range 
are available. The same 2010 survey of the eastern Bering Sea shelf 
provided an estimate of 1,061 (CV = 0.38) fin whales (Friday et al., 
2013). The estimate is not corrected for missed animals, but is 
expected to be robust as previous studies have shown that only small 
correction factors are needed for fin whales (Barlow, 1995). Zerbini et 
al. (2006) produced an estimate of 1,652 (95 percent CI: 1,142-2,389) 
fin whales for the area described above.
    Current and historical estimates of the abundance of sperm whales 
in the North Pacific are considered unreliable, and caution should be 
exercised in interpreting published estimates (Muto et al., 2017). 
However, Kato and Miyashita (1998) produced an abundance estimate of 
102,112 (CV = 0.155) sperm whales in the western North Pacific 
(believed to be positively biased). The number of sperm whales 
occurring within Alaska waters is unknown.
    Very little information is available regarding beaked whale stocks 
in Alaska, with no reliable abundance estimates available for any 
stock. Sightings of all beaked whale species are rare in Alaska, and 
their presence and distribution have mostly been inferred from 
stranding data. During long-term passive acoustic monitoring conducted 
at five sites in the Gulf of Alaska from 2011-15, all three species 
were detected at three sites located on the continental slope and 
offshore seamounts (Rice et al., 2021). There was no clear diel or 
interannual pattern for any species at any site. However, a different 
species was predominant at each site and, when detected at the same 
locations, detection peaks were all seasonally offset, demonstrating 
some degree of habitat partitioning. The authors noted that detections 
for all three beaked whale species were low throughout the summer. 
Stranding records exist for all three species of beaked whale in the 
survey area.
    Using 2010-2012 survey data for the inland waters of southeast 
Alaska, Dahlheim et al. (2015) calculated a combined abundance estimate 
for harbor porpoise in the northern (including Cross Sound, Icy Strait, 
Glacier Bay, Lynn Canal, Stephens Passage, and Chatham Strait) and 
southern (including Frederick Sound, Sumner Strait, Wrangell and 
Zarembo Islands, and Clarence Strait as far south as Ketchikan) regions 
of the inland waters of 975 (95 percent CI = 857-1,109). This abundance 
estimate was subsequently corrected for detection biases, which are 
expected to be high for harbor porpoise (Muto et al., 2020). The 
resulting abundance estimates are 553 harbor porpoise (CV = 0.13) in 
the northern inland waters and 801 harbor porpoise (CV = 0.15) in the 
southern inland waters (Muto et al., 2020).
    The Steller sea lion ranges from Japan, through the Okhotsk and 
Bering Seas, to central California. It consists of two morphologically, 
ecologically, and behaviorally separate DPSs: The Eastern, which 
includes sea lions in southeast Alaska, British Columbia, Washington, 
Oregon, and California; and the Western, which includes sea lions in 
all other regions of Alaska, as well as Russia and Japan. At the time 
of their initial listing under the ESA, Steller sea lions were 
considered a single population listed as threatened. In 1997, following 
a status review, NMFS established two DPSs of Steller sea lions, and 
issued a final determination to list the Western DPS as endangered 
under the ESA. The Eastern DPS of Steller sea lion was delisted in 
2013. According to Hastings et al. (2020), approximately 2.2 percent of 
Steller sea lions occurring in the proposed action area are likely to 
be from the Western DPS; the rest would be from the Eastern DPS.

Important Habitat

    Several biologically important areas (BIA) for marine mammals are 
recognized in southeast Alaska, and critical habitat is designated in 
southeast Alaska for the Steller sea lion (58 FR 45269; August 27, 
1993) and the Mexico DPS of humpback whale (86 FR 21082; April 21, 
2021). Note that although the eastern DPS of Steller sea lion was 
delisted in 2013, the change in listing status does not affect the 
designated critical habitat. Critical habitat is defined by section 3 
of the ESA as (1) the specific areas within the geographical area 
occupied by the species, at the time it is listed, on which are found 
those physical or biological features (a) essential to the conservation 
of the species and (b) which may require special management 
considerations or protection; and (2) specific areas outside the 
geographical area occupied by the

[[Page 30014]]

species at the time it is listed, upon a determination by the Secretary 
that such areas are essential for the conservation of the species.
    Mexico DPS humpback whale critical habitat includes marine waters 
in Washington, Oregon, California, and Alaska. Only the areas 
designated in southeast Alaska fall within the survey area. The 
relevant designated critical habitat (Unit 10) extends from 139[deg]24' 
W, southeastward to the U.S. border with Canada. The area also extends 
offshore to a boundary drawn along the 2,000-m isobath. The essential 
feature for Mexico DPS humpback whale critical habitat is prey species, 
primarily euphausiids and small pelagic schooling fishes of sufficient 
quality, abundance, and accessibility within humpback whale feeding 
areas to support feeding and population growth. This area was drawn to 
encompass well-established feeding grounds in southeast Alaska and an 
identified feeding BIA (86 FR 21082; April 21, 2021). Humpback whales 
occur year-round in this unit, with highest densities occurring in 
summer and fall (Baker et al., 1985, 1986).
    Critical habitat for humpback whales has been designated under 
Canadian law in four locations in British Columbia (DFO, 2013), 
including in the waters of the survey area off Haida Gwaii (Langara 
Island and Southeast Moresby Island). These areas show persistent 
aggregations of humpback whales and have features such as prey 
availability, suitable acoustic environment, water quality, and 
physical space that allow for feeding, foraging, socializing, and 
resting (DFO, 2013).
    Designated Steller sea lion critical habitat includes terrestrial, 
aquatic, and air zones that extend 3,000 ft (0.9 km) landward, seaward, 
and above each major rookery and major haul-out in Alaska. Within the 
survey area, critical habitat is located on islands off the coast of 
southeast Alaska (e.g., Sitka, Coronation Island, Noyes Island, and 
Forrester Island). The physical and biological features identified for 
the aquatic areas of Steller sea lion designated critical habitat that 
occur within the survey area are those that support foraging, such as 
adequate prey resources and available foraging habitat. The proposed 
survey tracklines do not directly overlap any areas of Steller sea lion 
critical habitat, though the extent of the estimated ensonified area 
associated with the survey would overlap with units of Steller sea lion 
critical habitat. However, the brief duration of ensonification for any 
critical habitat unit leads us to conclude that any impacts on Steller 
sea lion habitat would be insignificant and would not affect the 
conservation value of the critical habitat.
    For humpback whales, seasonal feeding BIAs for spring (March-May), 
summer (June-August), and fall (September-November) are recognized in 
southeast Alaska (Ferguson et al., 2015). It should be noted that the 
aforementioned designated critical habitat in the survey area was based 
in large part on the same information that informed an understanding of 
the BIAs. Though the BIAs are not synonymous with critical habitat 
designated under the ESA, they were regarded by the humpback whale 
critical habitat review team as an important source of information and 
informative to their review of areas that meet the definition of 
critical habitat for humpback whales (86 FR 21082; April 21, 2021). The 
aforementioned southeast Alaska unit of designated critical habitat 
encompasses the BIAs, with the offshore and nearshore boundaries 
corresponding with the BIA boundary.
    A separate feeding BIA is recognized in southeast Alaska for gray 
whales. Once considered only a migratory pathway, the Gulf of Alaska is 
now known to provide foraging and overwintering habitat for ENP gray 
whales (Ferguson et al., 2015). Based on the regular occurrence of 
feeding gray whales (including repeat sightings of individuals across 
years) off southeast Alaska, an area off of Sitka is recognized. The 
greatest densities of gray whales on the feeding area in southeast 
Alaska occur from May to November. However, this area is located to the 
north of the proposed survey area and would not be expected to be 
meaningfully impacted by the survey activities. A separate migratory 
BIA is recognized as extending along the continental shelf throughout 
the Gulf of Alaska. During their annual migration, most gray whales 
pass through the Gulf of Alaska in the fall (November through January; 
southbound) and again in the spring (March through May; northbound) 
(Ferguson et al., 2015). Therefore, the planned survey would not be 
expected to impact gray whale migratory habitat due to the timing of 
the survey in late summer. No important behaviors of gray whales in 
either the feeding or migratory BIAs are expected to be affected. For 
more information on BIAs, please see Ferguson et al. (2015) or visit 
https://oceannoise.noaa.gov/biologically-important-areas.

Unusual Mortality Events (UME)

    A UME is defined under the MMPA as ``a stranding that is 
unexpected; involves a significant die-off of any marine mammal 
population; and demands immediate response.'' For more information on 
UMEs, please visit: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-unusual-mortality-events. There is a currently 
ongoing UME affecting gray whales throughout their migratory range.
    Since January 1, 2019, elevated gray whale strandings have occurred 
along the west coast of North America from Mexico through Alaska. As of 
May 6, 2021, there have been a total of 454 whales reported in the 
event, with approximately 218 dead whales in Mexico, 218 whales in the 
United States (62 in California; 10 in Oregon; 53 in Washington, 93 in 
Alaska), and 18 whales in British Columbia, Canada. For the United 
States, the historical 18-year 5-month average (Jan-May) is 14.8 whales 
for the four states for this same time-period. Several dead whales have 
been emaciated with moderate to heavy whale lice (cyamid) loads. 
Necropsies have been conducted on a subset of whales with additional 
findings of vessel strike in three whales and entanglement in one 
whale. In Mexico, 50-55 percent of the free-ranging whales observed in 
the lagoons in winter have been reported as ``skinny'' compared to the 
annual average of 10-12 percent ``skinny'' whales normally seen. The 
cause of the UME is as yet undetermined. For more information, please 
visit: www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast-and.
    Another recent, notable UME involved large whales and occurred in 
the western Gulf of Alaska and off of British Columbia, Canada. 
Beginning in May 2015, elevated large whale mortalities (primarily fin 
and humpback whales) occurred in the areas around Kodiak Island, 
Afognak Island, Chirikof Island, the Semidi Islands, and the southern 
shoreline of the Alaska Peninsula. Although most carcasses have been 
non-retrievable as they were discovered floating and in a state of 
moderate to severe decomposition, the UME is likely attributable to 
ecological factors, i.e., the 2015 El Ni[ntilde]o, ``warm water blob,'' 
and the Pacific Coast domoic acid bloom. The UME was closed in 2016. 
More information is available online at www.fisheries.noaa.gov/national/marine-life-distress/2015-2016-large-whale-unusual-mortality-event-western-gulf-alaska.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals

[[Page 30015]]

underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et 
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect 
this, Southall et al. (2007) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 2.

                  Table 2--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
              Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen      7 Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans (dolphins,   150 Hz to 160 kHz.
 toothed whales, beaked whales,
 bottlenose whales).
High-frequency (HF) cetaceans (true       275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) (true  50 Hz to 86 kHz.
 seals).
Otariid pinnipeds (OW) (underwater) (sea  60 Hz to 39 kHz.
 lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Twenty-one marine mammal species (16 cetacean and 5 pinniped (3 otariid 
and 2 phocid) species) are considered herein. Of the cetacean species 
that may be present, six are classified as low-frequency cetaceans 
(i.e., all mysticete species), eight are classified as mid-frequency 
cetaceans (i.e., all delphinid and ziphiid species and the sperm 
whale), and two are classified as high-frequency cetaceans (i.e., 
porpoises).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a summary of the ways that L-DEO's specified 
activity may impact marine mammals and their habitat. Detailed 
descriptions of the potential effects of similar specified activities 
have been provided in other recent Federal Register notices, including 
for survey activities using the same methodology and over a similar 
amount of time, and affecting similar species (e.g., 83 FR 29212, June 
22, 2018; 84 FR 14200, April 9, 2019; 85 FR 19580, April 7, 2020). No 
significant new information is available, and we refer the reader to 
these documents for additional detail. The Estimated Take section 
includes a quantitative analysis of the number of individuals that are 
expected to be taken by L-DEO's activity. The Negligible Impact 
Analysis and Determination section considers the potential effects of 
the specified activity, the Estimated Take section, and the Proposed 
Mitigation section, to draw conclusions regarding the likely impacts of 
these activities on the reproductive success or survivorship of 
individuals and how those impacts on individuals are likely to impact 
marine mammal species or stocks.

Background on Active Acoustic Sound Sources and Acoustic Terminology

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used in this 
proposal inasmuch as the information is relevant to the specified 
activity and to the discussion of the effects of the specified activity 
on marine mammals in this document. For general information on sound 
and its interaction with the marine environment, please see, e.g., Au 
and Hastings (2008); Richardson et al. (1995); Urick (1983).
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz or cycles per second. Wavelength is the distance 
between two peaks or corresponding points of a sound wave (length of 
one cycle). Higher frequency sounds have shorter wavelengths than lower 
frequency sounds, and typically attenuate (decrease) more rapidly, 
except in certain cases in shallower water. Amplitude is the height of 
the sound pressure wave or the ``loudness'' of a sound and is typically 
described using the relative unit of the decibel. A sound pressure 
level (SPL) in dB is described as the ratio between a measured pressure 
and a reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)), and is a logarithmic unit that accounts for large variations 
in amplitude. Therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. The source level (SL) represents the 
SPL referenced at a distance of 1 m from the source (referenced to 1 
[mu]Pa), while the received level is the SPL at the listener's position 
(referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they

[[Page 30016]]

may be accounted for in the summation of pressure levels (Hastings and 
Popper, 2005). This measurement is often used in the context of 
discussing behavioral effects, in part because behavioral effects, 
which often result from auditory cues, may be better expressed through 
averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa2-s) 
represents the total energy in a stated frequency band over a stated 
time interval or event and considers both intensity and duration of 
exposure. The per-pulse SEL is calculated over the time window 
containing the entire pulse (i.e., 100 percent of the acoustic energy). 
SEL is a cumulative metric; it can be accumulated over a single pulse, 
or calculated over periods containing multiple pulses. Cumulative SEL 
represents the total energy accumulated by a receiver over a defined 
time window or during an event. Peak sound pressure (also referred to 
as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source and is represented in the same units as the rms sound pressure.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or may radiate in all directions 
(omnidirectional sources), as is the case for sound produced by the 
pile driving activity considered here. The compressions and 
decompressions associated with sound waves are detected as changes in 
pressure by aquatic life and man-made sound receptors such as 
hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound, which is 
defined as environmental background sound levels lacking a single 
source or point (Richardson et al., 1995). The sound level of a region 
is defined by the total acoustical energy being generated by known and 
unknown sources. These sources may include physical (e.g., wind and 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
(e.g., vessels, dredging, construction) sound. A number of sources 
contribute to ambient sound, including wind and waves, which are a main 
source of naturally occurring ambient sound for frequencies between 200 
hertz (Hz) and 50 kilohertz (kHz) (Mitson, 1995). In general, ambient 
sound levels tend to increase with increasing wind speed and wave 
height. Precipitation can become an important component of total sound 
at frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times. Marine mammals can contribute significantly to ambient sound 
levels, as can some fish and snapping shrimp. The frequency band for 
biological contributions is from approximately 12 Hz to over 100 kHz. 
Sources of ambient sound related to human activity include 
transportation (surface vessels), dredging and construction, oil and 
gas drilling and production, geophysical surveys, sonar, and 
explosions. Vessel noise typically dominates the total ambient sound 
for frequencies between 20 and 300 Hz. In general, the frequencies of 
anthropogenic sounds are below 1 kHz and, if higher frequency sound 
levels are created, they attenuate rapidly.
    The sum of the various natural and anthropogenic sound sources that 
comprise ambient sound at any given location and time depends not only 
on the source levels (as determined by current weather conditions and 
levels of biological and human activity) but also on the ability of 
sound to propagate through the environment. In turn, sound propagation 
is dependent on the spatially and temporally varying properties of the 
water column and sea floor, and is frequency-dependent. As a result of 
the dependence on a large number of varying factors, ambient sound 
levels can be expected to vary widely over both coarse and fine spatial 
and temporal scales. Sound levels at a given frequency and location can 
vary by 10-20 dB from day to day (Richardson et al., 1995). The result 
is that, depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals. Details of source types are described in the following text.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al. (2007) for an in-depth discussion of these concepts. 
The distinction between these two sound types is not always obvious, as 
certain signals share properties of both pulsed and non-pulsed sounds. 
A signal near a source could be categorized as a pulse, but due to 
propagation effects as it moves farther from the source, the signal 
duration becomes longer (e.g., Greene and Richardson, 1988).
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or intermittent (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems. The 
duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.
    Airgun arrays produce pulsed signals with energy in a frequency 
range from about 10-2,000 Hz, with most energy radiated at frequencies 
below 200 Hz. The amplitude of the acoustic wave emitted from the 
source is equal in all directions (i.e., omnidirectional), but airgun 
arrays do possess some directionality due to different phase delays 
between guns in different directions. Airgun arrays are typically tuned 
to maximize functionality for data acquisition purposes, meaning that 
sound transmitted in horizontal directions and at higher frequencies is 
minimized to the extent possible.

Summary on Specific Potential Effects of Acoustic Sound Sources

    Underwater sound from active acoustic sources can include one or 
more of the following: Temporary or permanent hearing impairment, non-
auditory physical or physiological effects, behavioral disturbance, 
stress, and masking. The degree of effect is intrinsically related to 
the signal characteristics, received level, distance from the source, 
and duration of the

[[Page 30017]]

sound exposure. Marine mammals exposed to high-intensity sound, or to 
lower-intensity sound for prolonged periods, can experience hearing 
threshold shift (TS), which is the loss of hearing sensitivity at 
certain frequency ranges (Finneran, 2015). TS can be permanent (PTS), 
in which case the loss of hearing sensitivity is not fully recoverable, 
or temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007).
    Due to the characteristics of airgun arrays as a distributed sound 
source, maximum estimated Level A harassment isopleths for species of 
certain hearing groups are assumed to fall within the near field of the 
array. For these species, i.e., mid-frequency cetaceans and all 
pinnipeds, animals in the vicinity of L-DEO's proposed seismic survey 
activity are unlikely to incur PTS. For low-frequency cetaceans and 
high-frequency cetaceans, potential exposures sufficient to cause low-
level PTS may occur on the basis of cumulative exposure level and 
instantaneous exposure to peak pressure levels, respectively. However, 
when considered in conjunction with the potential for aversive 
behavior, relative motion of the exposed animal and the sound source, 
and the anticipated efficacy of the proposed mitigation requirements, a 
reasonable conclusion may be drawn that PTS is not a likely outcome for 
any species. However, we propose to authorize take by Level A 
harassment, where indicated by the quantitative exposure analysis, for 
species from the low- and high-frequency cetacean hearing groups. 
Please see Estimated Take and Proposed Mitigation for further 
discussion.
    Behavioral disturbance may include a variety of effects, including 
subtle changes in behavior (e.g., minor or brief avoidance of an area 
or changes in vocalizations), more conspicuous changes in similar 
behavioral activities, and more sustained and/or potentially severe 
reactions, such as displacement from or abandonment of high-quality 
habitat. Behavioral responses to sound are highly variable and context-
specific and any reactions depend on numerous intrinsic and extrinsic 
factors (e.g., species, state of maturity, experience, current 
activity, reproductive state, auditory sensitivity, time of day), as 
well as the interplay between factors. Available studies show wide 
variation in response to underwater sound; therefore, it is difficult 
to predict specifically how any given sound in a particular instance 
might affect marine mammals perceiving the signal.
    In addition, sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation). Masking occurs when the receipt of a 
sound is interfered with by another coincident sound at similar 
frequencies and at similar or higher intensity, and may occur whether 
the sound is natural (e.g., snapping shrimp, wind, waves, 
precipitation) or anthropogenic (e.g., shipping, sonar, seismic 
exploration) in origin.
    Sound may affect marine mammals through impacts on the abundance, 
behavior, or distribution of prey species (e.g., crustaceans, 
cephalopods, fish, zooplankton) (i.e., effects to marine mammal 
habitat). Prey species exposed to sound might move away from the sound 
source, experience TTS, experience masking of biologically relevant 
sounds, or show no obvious direct effects. The most likely impacts (if 
any) for most prey species in a given area would be temporary avoidance 
of the area. Surveys using active acoustic sound sources move through 
an area relatively quickly, limiting exposure to multiple pulses. In 
all cases, sound levels would return to ambient once a survey ends and 
the noise source is shut down and, when exposure to sound ends, 
behavioral and/or physiological responses are expected to end 
relatively quickly. Finally, the survey equipment will not have 
significant impacts to the seafloor and does not represent a source of 
pollution.

Vessel Strike

    Vessel collisions with marine mammals, or ship strikes, can result 
in death or serious injury of the animal. These interactions are 
typically associated with large whales, which are less maneuverable 
than are smaller cetaceans or pinnipeds in relation to large vessels. 
The severity of injuries typically depends on the size and speed of the 
vessel, with the probability of death or serious injury increasing as 
vessel speed increases (Knowlton and Kraus, 2001; Laist et al., 2001; 
Vanderlaan and Taggart, 2007; Conn and Silber, 2013). Impact forces 
increase with speed, as does the probability of a strike at a given 
distance (Silber et al., 2010; Gende et al., 2011). The chances of a 
lethal injury decline from approximately 80 percent at 15 kn to 
approximately 20 percent at 8.6 kn. At speeds below 11.8 kn, the 
chances of lethal injury drop below 50 percent (Vanderlaan and Taggart, 
2007).
    Ship strikes generally involve commercial shipping, which is much 
more common in both space and time than is geophysical survey activity 
and which typically involves larger vessels moving at faster speeds. 
Jensen and Silber (2004) summarized ship strikes of large whales 
worldwide from 1975-2003 and found that most collisions occurred in the 
open ocean and involved large vessels (e.g., commercial shipping). 
Commercial fishing vessels were responsible for 3 percent of recorded 
collisions, while no such incidents were reported for geophysical 
survey vessels during that time period.
    For vessels used in geophysical survey activities, vessel speed 
while towing gear is typically only 4-5 kn. At these speeds, both the 
possibility of striking a marine mammal and the possibility of a strike 
resulting in serious injury or mortality are so low as to be 
discountable. At average transit speed for geophysical survey vessels 
(approximately 10 kn), the probability of serious injury or mortality 
resulting from a strike (if it occurred) is less than 50 percent 
(Vanderlaan and Taggart, 2007; Conn and Silber, 2013). However, the 
likelihood of a strike actually happening is again low given the 
smaller size of these vessels and generally slower speeds. We 
anticipate that vessel collisions involving seismic data acquisition 
vessels towing gear, while not impossible, represent unlikely, 
unpredictable events for which there are no preventive measures. Given 
the required mitigation measures, the relatively slow speeds of vessels 
towing gear, the presence of bridge crew watching for obstacles at all 
times (including marine mammals), the presence of marine mammal 
observers, and the small number of seismic survey cruises relative to 
commercial ship traffic, we believe that the possibility of ship strike 
is discountable and, further, that were a strike of a large whale to 
occur, it would be unlikely to result in serious injury or mortality. 
No incidental take resulting from ship strike is anticipated or 
proposed for authorization, and this potential effect of the specified 
activity will not be discussed further in the following analysis.
    The potential effects of L-DEO's specified survey activity are 
expected to be limited to Level B harassment consisting of behavioral 
harassment and/or temporary auditory effects and, for certain species 
of low- and high-frequency cetaceans only, low-level permanent auditory 
effects. No permanent auditory effects for any species belonging to 
other hearing groups, or significant impacts to marine

[[Page 30018]]

mammal habitat, including prey, are expected.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers'' and the negligible impact 
determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of 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).
    Authorized takes would primarily be by Level B harassment, as use 
of seismic airguns has the potential to result in disruption of 
behavioral patterns or temporary auditory effects for individual marine 
mammals. There is also some potential for auditory injury (Level A 
harassment) for low-frequency (i.e., mysticetes) and high-frequency 
cetaceans (i.e., porpoises). The proposed mitigation and monitoring 
measures are expected to minimize the severity of such taking to the 
extent practicable.
    As described previously, no serious injury or mortality is 
anticipated or proposed to be authorized for this activity. Below we 
describe how the take is estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and, (4) 
and the number of days of activities. We note that while these basic 
factors can contribute to a basic calculation to provide an initial 
prediction of takes, additional information that can qualitatively 
inform take estimates is also sometimes available (e.g., previous 
monitoring results or average group size). Below, we describe the 
factors considered here in more detail and present the proposed take 
estimate.

Acoustic Thresholds

    NMFS uses acoustic thresholds that identify the received level of 
underwater sound above which exposed marine mammals would be reasonably 
expected to be behaviorally harassed (equated to Level B harassment) or 
to incur PTS of some degree (equated to Level A harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source (e.g., frequency, predictability, duty cycle), the environment 
(e.g., bathymetry), and the receiving animals (hearing, motivation, 
experience, demography, behavioral context) and can be difficult to 
predict (Southall et al., 2007, Ellison et al., 2012). NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals may 
be behaviorally harassed (i.e., Level B harassment) when exposed to 
underwater anthropogenic noise above received levels of 160 dB re 1 
[mu]Pa (rms) for the impulsive sources (i.e., seismic airguns) 
evaluated here.
    Level A Harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). L-DEO's 
proposed seismic survey includes the use of impulsive (seismic airguns) 
sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
----------------------------------------------------------------------------------------------------------------
             Hearing group                        Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 219 dB;   Cell 2: L,E,LF,24h: 199 dB.
                                          L,E,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Cell 3: Lpk,flat: 230 dB;   Cell 4: L,E,MF,24h: 198 dB.
                                          L,E,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Cell 5: Lpk,flat: 202 dB;   Cell 6: L,E,HF,24h: 173 dB.
                                          L,E,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 218 dB;   Cell 8: L,E,PW,24h: 201 dB.
                                          L,E,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 232 dB;   Cell 10: L,E,OW,24h: 219 dB.
                                          L,E,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity and other relevant information that will feed into identifying 
the area ensonified above the acoustic thresholds.
    L-DEO's modeling methodologies are described in greater detail in 
Appendix A of L-DEO's IHA application. The proposed 2D survey would 
acquire data using the 36-airgun array with a total discharge volume of 
6,600 in\3\ at a maximum tow depth of 12 m. L-DEO's modeling approach 
uses ray tracing for

[[Page 30019]]

the direct wave traveling from the array to the receiver and its 
associated source ghost (reflection at the air-water interface in the 
vicinity of the array), in a constant-velocity half-space (infinite 
homogeneous ocean layer, unbounded by a seafloor). To validate the 
model results, L-DEO measured propagation of pulses from the 36-airgun 
array at a tow depth of 6 m in the Gulf of Mexico, for deep water 
(~1,600 m), intermediate water depth on the slope (~600-1,100 m), and 
shallow water (~50 m) (Tolstoy et al., 2009; Diebold et al., 2010).
    L-DEO collected a MCS data set from R/V Langseth (array towed at 9 
m depth) on an 8-km streamer in 2012 on the shelf of the Cascadia 
Margin off of Washington in water up to 200 m deep that allowed Crone 
et al. (2014) to analyze the hydrophone streamer data (>1,100 
individual shots). These empirical data were then analyzed to determine 
in situ sound levels for shallow and upper intermediate water depths. 
These data suggest that modeled radii were 2-3 times larger than the 
measured radii in shallow water. Similarly, data collected by Crone et 
al. (2017) during a survey off New Jersey in 2014 and 2015 confirmed 
that in situ measurements collected by the R/V Langseth hydrophone 
streamer were 2-3 times smaller than the predicted radii.
    L-DEO model results are used to determine the assumed radial 
distance to the 160-dB rms threshold for these arrays in deep water 
(>1,000 m) (down to a maximum water depth of 2,000 m). Water depths in 
the project area may be up to 2,800 m, but marine mammals in the region 
are generally not anticipated to dive below 2,000 m (e.g., Costa and 
Williams, 1999). L-DEO typically derives estimated distances for 
intermediate water depths by applying a correction factor of 1.5 to the 
model results for deep water. In this case, the estimated radial 
distance for intermediate (100-1,000 m) and shallow (<100 m) water 
depths is taken from Crone et al. (2014), as these empirical data were 
collected in the same region as this proposed survey. A correction 
factor of 1.15 was applied to account for differences in array tow 
depth.
    The estimated distances to the Level B harassment isopleths for the 
array are shown in Table 4.

         Table 4--Predicted Radial Distances to Isopleths Corresponding to Level B Harassment Threshold
----------------------------------------------------------------------------------------------------------------
                                                                                                      Level B
                        Source and volume                         Tow depth  (m)    Water depth     harassment
                                                                                        (m)          zone  (m)
----------------------------------------------------------------------------------------------------------------
36 airgun array; 6,600 in\3\....................................              12           >1000       \1\ 6,733
                                                                                        100-1000       \2\ 9,468
                                                                                            <100      \2\ 12,650
----------------------------------------------------------------------------------------------------------------
\1\ Distance based on L-DEO model results.
\2\ Based on empirical data from Crone et al. (2014) with scaling.

    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal hearing groups, were calculated based on 
modeling performed by L-DEO using the NUCLEUS source modeling software 
program and the NMFS User Spreadsheet, described below. The acoustic 
thresholds for impulsive sounds (e.g., airguns) contained in the 
Technical Guidance were presented as dual metric acoustic thresholds 
using both SELcum and peak sound pressure metrics (NMFS 
2018). As dual metrics, NMFS considers onset of PTS (Level A 
harassment) to have occurred when either one of the two metrics is 
exceeded (i.e., metric resulting in the largest isopleth). The 
SELcum metric considers both level and duration of exposure, 
as well as auditory weighting functions by marine mammal hearing group. 
In recognition of the fact that the requirement to calculate Level A 
harassment ensonified areas could be more technically challenging to 
predict due to the duration component and the use of weighting 
functions in the new SELcum thresholds, NMFS developed an 
optional User Spreadsheet that includes tools to help predict a simple 
isopleth that can be used in conjunction with marine mammal density or 
occurrence to facilitate the estimation of take numbers.
    The values for SELcum and peak SPL for the Langseth 
airgun arrays were derived from calculating the modified far-field 
signature. The farfield signature is often used as a theoretical 
representation of the source level. To compute the farfield signature, 
the source level is estimated at a large distance below the array 
(e.g., 9 km), and this level is back projected mathematically to a 
notional distance of 1 m from the array's geometrical center. However, 
when the source is an array of multiple airguns separated in space, the 
source level from the theoretical farfield signature is not necessarily 
the best measurement of the source level that is physically achieved at 
the source (Tolstoy et al., 2009). Near the source (at short ranges, 
distances <1 km), the pulses of sound pressure from each individual 
airgun in the source array do not stack constructively, as they do for 
the theoretical farfield signature. The pulses from the different 
airguns spread out in time such that the source levels observed or 
modeled are the result of the summation of pulses from a few airguns, 
not the full array (Tolstoy et al., 2009). At larger distances, away 
from the source array center, sound pressure of all the airguns in the 
array stack coherently, but not within one time sample, resulting in 
smaller source levels (a few dB) than the source level derived from the 
farfield signature. Because the farfield signature does not take into 
account the large array effect near the source and is calculated as a 
point source, the modified farfield signature is a more appropriate 
measure of the sound source level for distributed sound sources, such 
as airgun arrays. L-DEO used the acoustic modeling methodology as used 
for estimating Level B harassment distances with a small grid step of 1 
m in both the inline and depth directions. The propagation modeling 
takes into account all airgun interactions at short distances from the 
source, including interactions between subarrays, which are modeled 
using the NUCLEUS software to estimate the notional signature and 
MATLAB software to calculate the pressure signal at each mesh point of 
a grid.
    In order to more realistically incorporate the Technical Guidance's 
weighting functions over the seismic array's full acoustic band, 
unweighted spectrum data for the Langseth's airgun array (modeled in 1 
Hz bands) was used to make adjustments (dB) to the unweighted spectrum 
levels, by frequency, according to the weighting functions for each 
relevant marine mammal hearing group. These adjusted/weighted spectrum 
levels were then converted to pressures ([mu]Pa) in order to integrate 
them over the entire

[[Page 30020]]

broadband spectrum, resulting in broadband weighted source levels by 
hearing group that could be directly incorporated within the User 
Spreadsheet (i.e., to override the Spreadsheet's more simple weighting 
factor adjustment). Using the User Spreadsheet's ``safe distance'' 
methodology for mobile sources (described by Sivle et al., 2014) with 
the hearing group-specific weighted source levels, and inputs assuming 
spherical spreading propagation and information specific to the planned 
survey (i.e., the 2.2 m/s source velocity and (worst-case) 23-s shot 
interval), potential radial distances to auditory injury zones were 
then calculated for SELcum thresholds.
    Inputs to the User Spreadsheets in the form of estimated source 
levels are shown in Appendix A of L-DEO's application. User 
Spreadsheets used by L-DEO to estimate distances to Level A harassment 
isopleths for the airgun arrays are also provided in Appendix A of the 
application. Outputs from the User Spreadsheets in the form of 
estimated distances to Level A harassment isopleths for the survey are 
shown in Table 5. As described above, NMFS considers onset of PTS 
(Level A harassment) to have occurred when either one of the dual 
metrics (SELcum and Peak SPLflat) is exceeded 
(i.e., metric resulting in the largest isopleth).

        Table 5--Modeled Radial Distances (m) to Isopleths Corresponding to Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                                  Level A harassment zone (m)
                                             -------------------------------------------------------------------
       Source (volume)           Threshold                                        HF
                                               LF cetaceans    MF cetaceans    cetaceans    Phocids    Otariids
----------------------------------------------------------------------------------------------------------------
36-airgun array (6,600        SELcum........             320               0           1          10           0
 in\3\).
                              Peak..........              39              14         268          44          11
----------------------------------------------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used (e.g., stationary receiver with no vertical or horizontal 
movement in response to the acoustic source), isopleths produced may be 
overestimates to some degree, which will ultimately result in some 
degree of overestimation of Level A harassment. However, these tools 
offer the best way to predict appropriate isopleths when more 
sophisticated modeling methods are not available, and NMFS continues to 
develop ways to quantitatively refine these tools and will 
qualitatively address the output where appropriate. For mobile sources, 
such as the proposed seismic survey, the User Spreadsheet predicts the 
closest distance at which a stationary animal would not incur PTS if 
the sound source traveled by the animal in a straight line at a 
constant speed.
    Auditory injury is unlikely to occur for mid-frequency cetaceans, 
otariid pinnipeds, and phocid pinnipeds given very small modeled zones 
of injury for those species (all estimated zones less than 15 m for 
mid-frequency cetaceans and otariid pinnipeds, up to a maximum of 44 m 
for phocid pinnipeds), in context of distributed source dynamics. The 
source level of the array is a theoretical definition assuming a point 
source and measurement in the far-field of the source (MacGillivray, 
2006). As described by Caldwell and Dragoset (2000), an array is not a 
point source, but one that spans a small area. In the far-field, 
individual elements in arrays will effectively work as one source 
because individual pressure peaks will have coalesced into one 
relatively broad pulse. The array can then be considered a ``point 
source.'' For distances within the near-field, i.e., approximately 2-3 
times the array dimensions, pressure peaks from individual elements do 
not arrive simultaneously because the observation point is not 
equidistant from each element. The effect is destructive interference 
of the outputs of each element, so that peak pressures in the near-
field will be significantly lower than the output of the largest 
individual element. Here, the relevant peak isopleth distances would in 
all cases be expected to be within the near-field of the array where 
the definition of source level breaks down. Therefore, actual locations 
within this distance of the array center where the sound level exceeds 
the relevant peak SPL thresholds would not necessarily exist. In 
general, Caldwell and Dragoset (2000) suggest that the near-field for 
airgun arrays is considered to extend out to approximately 250 m.
    In order to provide quantitative support for this theoretical 
argument, we calculated expected maximum distances at which the near-
field would transition to the far-field (Table 5). For a specific array 
one can estimate the distance at which the near-field transitions to 
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN04JN21.004

with the condition that D >> [lambda], and where D is the distance, L 
is the longest dimension of the array, and [lambda] is the wavelength 
of the signal (Lurton, 2002). Given that [lambda] can be defined by:
[GRAPHIC] [TIFF OMITTED] TN04JN21.005

where f is the frequency of the sound signal and v is the speed of the 
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN04JN21.006

and calculate D directly given a particular frequency and known speed 
of sound (here assumed to be 1,500 meters per second in water, although 
this varies with environmental conditions).
    To determine the closest distance to the arrays at which the source 
level predictions in Table 5 are valid (i.e., maximum extent of the 
near-field), we calculated D based on an assumed frequency of 1 kHz. A 
frequency of 1 kHz is commonly used in near-field/far-field 
calculations for airgun arrays (Zykov and Carr, 2014; MacGillivray, 
2006; NSF and USGS, 2011), and based on representative airgun spectrum 
data and field measurements of an airgun array used on the Langseth, 
nearly all (greater than 95 percent) of the energy from airgun arrays 
is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz as the upper 
cut-off for calculating the maximum extent of the near-field should 
reasonably represent the near-field extent in field conditions.
    If the largest distance to the peak sound pressure level threshold 
was equal to or less than the longest dimension of the array (i.e., 
under the array), or within the near-field, then received levels that 
meet or exceed the threshold in most cases are not expected to occur. 
This is because within the near-field and within the dimensions of the 
array, the source levels specified in Appendix A of L-DEO's application 
are

[[Page 30021]]

overestimated and not applicable. In fact, until one reaches a distance 
of approximately three or four times the near-field distance the 
average intensity of sound at any given distance from the array is 
still less than that based on calculations that assume a directional 
point source (Lurton, 2002). The 6,600-in\3\ airgun array planned for 
use during the proposed survey has an approximate diagonal of 28.8 m, 
resulting in a near-field distance of 138.7 m at 1 kHz (NSF and USGS, 
2011). Field measurements of this array indicate that the source 
behaves like multiple discrete sources, rather than a directional point 
source, beginning at approximately 400 m (deep site) to 1 km (shallow 
site) from the center of the array (Tolstoy et al., 2009), distances 
that are actually greater than four times the calculated 140-m near-
field distance. Within these distances, the recorded received levels 
were always lower than would be predicted based on calculations that 
assume a directional point source, and increasingly so as one moves 
closer towards the array (Tolstoy et al., 2009). Given this, relying on 
the calculated distance (138.7 m) as the distance at which we expect to 
be in the near-field is a conservative approach since even beyond this 
distance the acoustic modeling still overestimates the actual received 
level. Within the near-field, in order to explicitly evaluate the 
likelihood of exceeding any particular acoustic threshold, one would 
need to consider the exact position of the animal, its relationship to 
individual array elements, and how the individual acoustic sources 
propagate and their acoustic fields interact. Given that within the 
near-field and dimensions of the array source levels would be below 
those assumed here, we believe exceedance of the peak pressure 
threshold would only be possible under highly unlikely circumstances.
    In consideration of the received sound levels in the near-field as 
described above, we expect the potential for Level A harassment of mid-
frequency cetaceans, otariid pinnipeds, and phocid pinnipeds to be de 
minimis, even before the likely moderating effects of aversion and/or 
other compensatory behaviors (e.g., Nachtigall et al., 2018) are 
considered. We do not believe that Level A harassment is a likely 
outcome for any mid-frequency cetacean, otariid pinniped, or phocid 
pinniped and do not propose to authorize any Level A harassment for 
these species.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, and group dynamics of marine mammals that will inform the take 
calculations. The Navy's Marine Species Density Database (DoN, 2019, 
2021) is currently the most comprehensive compendium for density data 
available for the Gulf of Alaska (GOA) and is the only source of 
density data available for southeast Alaska. Habitat-based stratified 
marine mammal densities developed by the U.S. Navy for assessing 
potential impacts of training activities in the GOA (DoN, 2021; Rone et 
al., 2014, 2017) and at Behm Canal in southeast Alaska (DoN, 2019) 
represent the best available information for estimating potential 
marine mammal exposures. The Navy's GOA Temporary Marine Activities 
Area (TMAA) is situated south of Prince William Sound and east of 
Kodiak Island. The northern boundary of the TMAA is approximately 24 
nautical miles south of the Kenai Peninsula. Behm Canal is 
approximately 45 km east of Ketchikan, AK, inshore of the proposed 
survey area in the same general part of southeast Alaska. In general, 
GOA density values were used for offshore (deep water depths) portions 
of the survey area, and Behm Canal density values were used for inshore 
(shallow and intermediate water depths) portions. For some species, no 
Behm Canal density information is available, and the GOA density value 
was applied to all water depths. Density values are provided in Table 6 
and discussed in greater detail below.

                                Table 6--Estimated Density Values by Water Depth
                                                     [#/km2]
----------------------------------------------------------------------------------------------------------------
                                                                                  Intermediate      Deep depth
                           Species                             Shallow depth   depth  (100-1,000   (>1,000 m) 1
                                                                 (<100 m) 1           m) 1
----------------------------------------------------------------------------------------------------------------
Gray whale \4\..............................................           0.0486             0.0486               0
Humpback whale..............................................       \3\ 0.0117         \3\ 0.0117      \4\ 0.0010
Blue whale \4\..............................................           0.0001             0.0001          0.0005
Fin whale...................................................       \3\ 0.0001         \3\ 0.0001      \4\ 0.0160
Sei whale \4\...............................................           0.0004             0.0004          0.0004
Minke whale.................................................       \3\ 0.0008         \3\ 0.0008      \4\ 0.0006
Sperm whale \4\.............................................                0             0.0020          0.0013
Baird's beaked whale \4\....................................                0                  0          0.0005
Stejneger's beaked whale \4\................................                0                  0          0.0021
Cuvier's beaked whale \4\...................................                0                  0          0.0020
Pacific white-sided dolphin.................................       \3\ 0.0075         \3\ 0.0075      \4\ 0.0200
Northern right whale dolphin \5\............................           0.0110             0.0276          0.0367
Risso's dolphin \2\.........................................           0.0000             0.0000          0.0000
Killer whale................................................       \3\ 0.0057         \3\ 0.0057      \4\ 0.0020
Dall's porpoise.............................................       \3\ 0.1210         \3\ 0.1210      \4\ 0.0370
Harbor porpoise \6\.........................................           0.0330             0.0330               0
Northern fur seal \4\.......................................           0.0661             0.0661          0.0661
California sea lion \3\.....................................           0.0288             0.0288          0.0065
Steller sea lion............................................       \3\ 0.3162         \4\ 0.0570               0
Northern elephant seal \4\..................................           0.0779             0.0779          0.0779
Harbor seal.................................................       \3\ 0.7811         \4\ 0.1407               0
----------------------------------------------------------------------------------------------------------------
\1\ A zero value indicates the species is not expected to occur in that depth stratum.
\2\ Nominal density value of 0.00001 applied to Risso's dolphin.
\3\ Source: DoN, 2019; \4\ Source DoN, 2021; \5\ Source: Becker et al. (2016); \6\ Hobbs and Waite (2010).


[[Page 30022]]

    The Navy conducted comprehensive marine mammal surveys in theTMAA 
in 2009 and 2013. Additional survey effort was conducted in 2015. These 
surveys used systematic line-transect survey protocols including visual 
and acoustic detection methods (Rone et al., 2010, 2014, 2017). The 
data were collected in four strata that were designed to encompass the 
four distinct habitats within the TMAA and greater GOA: Inshore: All 
waters <1,000 m deep; Slope: From 1,000 m water depth to the Aleutian 
trench/subduction zone; Offshore: Waters offshore of the Aleutian 
trench/subduction zone; Seamount: Waters within defined seamount areas. 
Density values for the slope and seamount regions of the TMAA are not 
relevant for the survey area considered herein. There were insufficient 
sightings data from the 2009, 2013, and 2015 line-transect surveys to 
calculate reliable density estimates for certain cetacean species in 
the GOA. In these cases, other available information supported 
development of density estimates. Additional sources of information 
include summer 2003 cetacean surveys near the Kenai Peninsula, within 
Prince William Sound and around Kodiak Island (Waite, 2003 in DoN, 
2021), summer 2010-2012 line-transect data collected over a broad area 
north of 40[deg] N, south of the Aleutian Islands, and between 170[deg] 
E and 135[deg] W during the International Whaling Commission-Pacific 
Ocean Whale and Ecosystem Research cruises (Hakamada et al., 2017), and 
analysis of acoustic data from the 2013 Navy-funded survey effort in 
the TMAA (Yack et al., 2015). See DoN (2021) for additional detail. 
When seasonal densities were available, the calculated exposures were 
based on summer densities, which are most representative of the 
proposed survey timing.
    Pinniped numbers are commonly assessed by counting individuals at 
haul-outs or the number of pups weaned at rookeries. Translating these 
numbers to in-water densities presents challenges unique to pinnipeds. 
No in-water line transect survey data were available for harbor seal, 
Steller sea lion, or California sea lion in the GOA. Surveys conducted 
by Rone et al. (2014) recorded sightings of northern elephant seal and 
northern fur seal in the TMAA; however, these data were insufficient to 
estimate a density for northern elephant seal, and were not used for 
northern fur seal due to the availability of more recent data. To 
account for the lack of in-water survey data for pinnipeds, published 
abundance estimates used in the density calculations were adjusted 
using a species-specific haul-out factor to estimate an in-water 
abundance for each species based on haul-out behavior. The calculated 
in-water abundance and an area of distribution specific to each species 
was used to estimate a density. See DoN (2021) for additional 
information. For pinnipeds, where monthly density estimates were 
available, the highest value from July or August was applied as most 
representative of the proposed survey timing.
    Due to a lack of sighting data specific to the Behm Canal area, the 
Navy derived density estimates based on data collected from various 
surveys (cetaceans) and shore counts (pinnipeds) conducted within 
southeast Alaska and GOA. Pinniped density estimates for the Behm Canal 
region were additionally derived from publications, NMFS SARs, and 
consultation with subject matter experts (DoN, 2019). Systematic ship 
surveys conducted in southeast Alaska waters from 1991 to 2012 provided 
data to develop stratified line-transect density estimates for harbor 
porpoise and Dall's porpoise in regions overlapping a portion of the 
Behm Canal area (Dahlheim et al., 2015). Density information for the 
Behm Canal area is available for the following species: Minke whale, 
fin whale, humpback whale, Pacific white-sided dolphin, killer whale, 
harbor porpoise, Dall's porpoise, and for all potentially affected 
pinniped species.
    The general approach for cetaceans of applying Behm Canal density 
estimates to survey effort in shallow and intermediate depth strata and 
GOA offshore density estimates to the deep depth stratum was applied 
for species for which appropriate estimates were available: Humpback 
whale, fin whale, minke whale, Pacific white-sided dolphin, killer 
whale, and Dall's porpoise. Note that, for killer whales, Behm Canal 
densities are provided specific to transient and resident whales. We 
apply the higher transient killer whale density value to estimate 
killer whale exposures in shallow and intermediate water depths. Behm 
Canal pinniped densities would be expected to overestimate pinniped 
occurrence off the coast, and so were not used for intermediate-depth 
waters, but were applied to shallow waters where available.
    Certain species are not expected to occur in Behm Canal: Gray 
whale, blue whale, sei whale, sperm whale, beaked whales, northern fur 
seal, and northern elephant seal. For these species, we applied 
appropriate GOA density values to all depth strata (i.e., inshore GOA 
values to shallow and intermediate water depths and offshore GOA 
density values to deep water depths). Note that, while DoN (2021) 
provides an inshore density estimate for sperm whales, that stratum 
corresponds to water depths <1,000 m. We assume here that sperm whales 
do not occur in shallow water depths (<100 m).
    Gray whale densities are provided for two zones, nearshore (0-2.25 
nmi from shore) and offshore (from 2.25-20 nmi from shore), based on 
density information in Carretta et al. (2000) and zones based on data 
from Shelden and Laake (2002). DoN (2021) assumes that gray whales do 
not occur in the region >20 nmi from shore. The nearshore density is 
used here to represent shallow and intermediate water (<1,000 m deep). 
This approach assumes a higher density of gray whales across a larger 
area and is used as a precautionary approach.
    Harbor porpoise densities in DoN (2021) were derived from survey 
data collected in summer 1997 in southeast Alaska and 1998 in the Gulf 
of Alaska and included correction factors for both perception and 
availability bias (Hobbs and Waite, 2010). L-DEO proposed to use 
density information from Hobbs and Waite (2010) specific to southeast 
Alaska, which better represents the survey area than the GOA 
information presented for harbor porpoise in DoN (2021). Following DoN 
(2021), we assume harbor porpoise will not occur in deep water (>1,000 
m).
    No regional density information is available for the northern right 
whale dolphin. Becker et al. (2016) used line-transect survey data 
collected between 1991 and 2009 to develop predictive habitat-based 
models of cetacean densities in the California Current Ecosystem (the 
region from Baja California to southern British Columbia). The modeled 
density estimates were available on the scale of 7 km by 10 km grid 
cells off California, Oregon, and Washington, and values were averaged 
for grid cells across Washington and Oregon corresponding with L-DEO's 
shallow, intermediate, and deep water survey strata. These density 
values were applied to the portion of the survey area off Canada to 
calculate estimated exposures, as northern right whale dolphins do not 
typically occur beyond the California Current. The Risso's dolphin is 
only rarely observed in or near the Navy's GOA survey area, and does 
not occur in Behm Canal, so minimal densities were used to represent 
their potential presence (DoN, 2021). For California sea lion, density 
data is available in DoN (2021); however, it is likely that these

[[Page 30023]]

values would underestimate presence of California sea lions in the 
proposed survey area. Therefore, information available in DoN (2019) 
for the Offshore Northwest Training and Testing (NWTT) Area (off 
Washington/Oregon) in the month of August was used; densities for 0-40 
km from shore were applied to shallow and intermediate water depths, 
and the density for 0-450 km from shore was used for deep water. The 
density for 40-70 km from shore was the lowest and was therefore not 
used.
    In British Columbia, several systematic surveys have been conducted 
in coastal waters (e.g., Williams and Thomas 2007; Ford et al., 2010; 
Best et al., 2015; Harvey et al., 2017). Surveys in coastal as well as 
offshore waters were conducted by Fisheries and Oceans Canada (DFO) 
during 2002 to 2008. However, density estimates for the survey areas 
outside the U.S. EEZ, i.e., in the Canadian EEZ, were not readily 
available, so density estimates for U.S. waters were applied to the 
entire survey area.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. In order to estimate 
the number of marine mammals predicted to be exposed to sound levels 
that would result in Level A or Level B harassment, radial distances 
from the airgun array to predicted isopleths corresponding to the Level 
A harassment and Level B harassment thresholds are calculated, as 
described above. Those radial distances are then used to calculate the 
area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the Level A and Level B harassment thresholds. The 
distance for the 160-dB threshold (based on L-DEO model results) was 
used to draw a buffer around every transect line in GIS to determine 
the total ensonified area in each depth category. Estimated incidents 
of exposure above Level A and Level B harassment criteria are presented 
in Table 7. For additional details regarding calculations of ensonified 
area, please see Appendix D of L-DEO's application. As noted 
previously, L-DEO has added 25 percent in the form of operational days, 
which is equivalent to adding 25 percent to the proposed line-kms to be 
surveyed. This accounts for the possibility that additional operational 
days are required, but likely results in an overestimate of actual 
exposures.
    As previously noted, NMFS cannot authorize incidental take under 
the MMPA that may occur within the territorial seas of foreign nations 
(from 0-12 nmi (22.2 km) from shore), as the MMPA does not apply in 
those waters. However, NMFS has still calculated the estimated level of 
incidental take in the entire activity area (including Canadian 
territorial waters) as part of the analysis supporting our 
determination under the MMPA that the activity will have a negligible 
impact on the affected species. The total estimated take in U.S. and 
Canadian waters is presented in Table 8 (see Negligible Impact Analysis 
and Determination).
    The estimated marine mammal exposures above harassment thresholds 
are generally assumed here to equate to take, and the estimates form 
the basis for our proposed take authorization numbers. For the species 
for which NMFS does not expect there to be a reasonable potential for 
take by Level A harassment to occur, i.e., mid-frequency cetaceans and 
all pinnipeds, the estimated exposures above Level A harassment 
thresholds have been added to the estimated exposures above the Level B 
harassment threshold to produce a total number of incidents of take by 
Level B harassment that is proposed for authorization. Estimated 
exposures and proposed take numbers for authorization are shown in 
Table 7. Regarding humpback whale take numbers, we assume that whales 
encountered will follow Wade (2017), i.e., that 96.1 percent of takes 
would accrue to the Hawaii DPS and 3.8 percent to the Mexico DPS. Of 
the estimated take of gray whales, and based on guidance provided 
through interagency consultation under section 7 of the ESA, we assume 
that 0.1 percent of encountered whales would be from the WNP stock and 
propose to authorize take accordingly. For Steller sea lions, 2.2 
percent are assumed to belong to the western DPS (Hastings et al., 
2020).

                                Table 7--Estimated Taking by Level A and Level B Harassment, and Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Estimated    Estimated     Proposed     Proposed
                  Species                               Stock 1               Level B      Level A      Level B      Level A     Total take   Percent of
                                                                             harassment   harassment   harassment   harassment                 stock 1
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray whale.................................  WNP..........................        1,450           45            2            0            2          0.7
                                             ENP..........................                                  1,448           45        1,493          5.5
Humpback whale.............................  .............................          403           14          403           14          417          4.1
Blue whale.................................  .............................           31            1           31            1           32          2.1
Fin whale \2\..............................  .............................          873           44          873           44          917          n/a
Sei whale..................................  .............................           34            1           34            1           35          6.7
Minke whale \2\............................  .............................           57            2           57            2           59          n/a
Sperm whale \2\............................  .............................          131            0          131            0          131          n/a
Baird's beaked whale \2\...................  .............................           29            0           29            0           29          n/a
Stejneger's beaked whale \2\...............  .............................          120            0          120            0          120          n/a
Cuvier's beaked whale \2\..................  .............................          114            0          114            0          114          n/a
Pacific white-sided dolphin................  .............................        1,371            3        1,374            0        1,374          5.1
Northern right whale dolphin...............  .............................          922            5          927            0          927          3.5
Risso's dolphin \3\........................  .............................            1            0           22            0           22          0.3
Killer whale...............................  Offshore.....................          290            0          290            0          290         96.7
                                             GOA/BSAI Transient...........                                                                          49.4
                                             WC Transient.................                                                                          83.1
                                             AK Resident..................                                                                          12.4
                                             Northern Resident............                                                                          96.0
Dall's porpoise............................  .............................        5,661          178        5,661          178        5,839          7.0
Harbor porpoise............................  .............................          990           26          990           26        1,016          n/a
Northern fur seal..........................  .............................        5,804            8        5,812            0        5,812          1.0
California sea lion........................  .............................        1,256            1        1,258            0        1,258          0.5
Steller sea lion...........................  WDPS.........................        2,433            2           54            0           54          0.1
                                             EDPS.........................                                  2,381            0        2,381          5.5
Northern elephant seal.....................  .............................        6,811           39        6,850            0        6,850          3.8
Harbor seal................................  Sitka/Chatham Strait.........        5,992           21        6,012            0        6,012         45.2
                                             Dixon/Cape Decision..........                                                                          25.6

[[Page 30024]]

 
                                             Clarence Strait..............                                                                          21.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ In most cases, where multiple stocks are being affected, for the purposes of calculating the percentage of the stock impacted, the take is being
  analyzed as if all proposed takes occurred within each stock. Where necessary, additional discussion is provided in the Small Numbers section.
\2\ As noted in Table 1, there is no estimate of abundance available for these species.
\3\ Estimated exposure of one Risso's dolphin increased to group size of 22 (Barlow, 2016).

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    In order to satisfy the MMPA's least practicable adverse impact 
standard, NMFS has evaluated a suite of basic mitigation protocols for 
seismic surveys that are required regardless of the status of a stock. 
Additional or enhanced protections may be required for species whose 
stocks are in particularly poor health and/or are subject to some 
significant additional stressor that lessens that stock's ability to 
weather the effects of the specified activities without worsening its 
status. We reviewed seismic mitigation protocols required or 
recommended elsewhere (e.g., HESS, 1999; DOC, 2013; IBAMA, 2018; Kyhn 
et al., 2011; JNCC, 2017; DEWHA, 2008; BOEM, 2016; DFO, 2008; GHFS, 
2015; MMOA, 2016; Nowacek et al., 2013; Nowacek and Southall, 2016), 
recommendations received during public comment periods for previous 
actions, and the available scientific literature. We also considered 
recommendations given in a number of review articles (e.g., Weir and 
Dolman, 2007; Compton et al., 2008; Parsons et al., 2009; Wright and 
Cosentino, 2015; Stone, 2015b). This exhaustive review and 
consideration of public comments regarding previous, similar activities 
has led to development of the protocols included here.

Vessel-Based Visual Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual protected species observers (PSOs)) to scan the 
ocean surface for the presence of marine mammals. The area to be 
scanned visually includes primarily the exclusion zone (EZ), within 
which observation of certain marine mammals requires shutdown of the 
acoustic source, but also a buffer zone and, to the extent possible 
depending on conditions, the surrounding waters. The buffer zone means 
an area beyond the EZ to be monitored for the presence of marine 
mammals that may enter the EZ. During pre-start clearance monitoring 
(i.e., before ramp-up begins), the buffer zone also acts as an 
extension of the EZ in that observations of marine mammals within the 
buffer zone would also prevent airgun operations from beginning (i.e., 
ramp-up). The buffer zone encompasses the area at and below the sea 
surface from the edge of the 0-500 m EZ, out to a radius of 1,000 m 
from the edges of the airgun array (500-1,000 m). This 1,000-m zone (EZ 
plus buffer) represents the pre-start clearance zone. Visual monitoring 
of the EZ and adjacent waters is intended to establish and, when visual 
conditions allow, maintain zones around the sound source that are clear 
of marine mammals, thereby reducing or eliminating the potential for 
injury and minimizing the potential for more severe behavioral 
reactions for animals occurring closer to the vessel. Visual monitoring 
of the buffer zone is intended to (1) provide additional protection to 
na[iuml]ve marine mammals that may be in the area during pre-start 
clearance, and (2) during airgun use, aid in establishing and 
maintaining the EZ by alerting the visual observer and crew of marine 
mammals that are outside of, but may approach and enter, the EZ.
    L-DEO must use dedicated, trained, NMFS-approved PSOs. The PSOs 
must have no tasks other than to conduct observational effort, record 
observational data, and communicate with and instruct relevant vessel 
crew with regard to the presence of marine mammals and mitigation 
requirements. PSO resumes shall be provided to NMFS for approval.
    At least one of the visual and two of the acoustic PSOs (discussed 
below) aboard the vessel must have a minimum of 90 days at-sea 
experience working in those roles, respectively, with no more than 18 
months elapsed since the conclusion of the at-sea experience. One 
visual PSO with such experience shall be designated as the lead for the 
entire protected species observation team. The lead PSO shall serve as 
primary point of contact for the vessel operator and ensure all PSO 
requirements per the IHA are met. To the maximum extent practicable, 
the experienced PSOs should be scheduled to be on duty with those PSOs 
with appropriate training but who have not yet gained relevant 
experience.
    During survey operations (e.g., any day on which use of the 
acoustic source is planned to occur, and whenever the

[[Page 30025]]

acoustic source is in the water, whether activated or not), a minimum 
of two visual PSOs must be on duty and conducting visual observations 
at all times during daylight hours (i.e., from 30 minutes prior to 
sunrise through 30 minutes following sunset). Visual monitoring of the 
pre-start clearance zone must begin no less than 30 minutes prior to 
ramp-up, and monitoring must continue until one hour after use of the 
acoustic source ceases or until 30 minutes past sunset. Visual PSOs 
shall coordinate to ensure 360[deg] visual coverage around the vessel 
from the most appropriate observation posts, and shall conduct visual 
observations using binoculars and the naked eye while free from 
distractions and in a consistent, systematic, and diligent manner.
    PSOs shall establish and monitor the exclusion and buffer zones. 
These zones shall be based upon the radial distance from the edges of 
the acoustic source (rather than being based on the center of the array 
or around the vessel itself). During use of the acoustic source (i.e., 
anytime airguns are active, including ramp-up), detections of marine 
mammals within the buffer zone (but outside the EZ) shall be 
communicated to the operator to prepare for the potential shutdown of 
the acoustic source. Visual PSOs will immediately communicate all 
observations to the on duty acoustic PSO(s), including any 
determination by the PSO regarding species identification, distance, 
and bearing and the degree of confidence in the determination. Any 
observations of marine mammals by crew members shall be relayed to the 
PSO team. During good conditions (e.g., daylight hours; Beaufort sea 
state (BSS) 3 or less), visual PSOs shall conduct observations when the 
acoustic source is not operating for comparison of sighting rates and 
behavior with and without use of the acoustic source and between 
acquisition periods, to the maximum extent practicable.
    Visual PSOs may be on watch for a maximum of 4 consecutive hours 
followed by a break of at least one hour between watches and may 
conduct a maximum of 12 hours of observation per 24-hour period. 
Combined observational duties (visual and acoustic but not at same 
time) may not exceed 12 hours per 24-hour period for any individual 
PSO.

Passive Acoustic Monitoring

    Acoustic monitoring means the use of trained personnel (sometimes 
referred to as passive acoustic monitoring (PAM) operators, herein 
referred to as acoustic PSOs) to operate PAM equipment to acoustically 
detect the presence of marine mammals. Acoustic monitoring involves 
acoustically detecting marine mammals regardless of distance from the 
source, as localization of animals may not always be possible. Acoustic 
monitoring is intended to further support visual monitoring (during 
daylight hours) in maintaining an EZ around the sound source that is 
clear of marine mammals. In cases where visual monitoring is not 
effective (e.g., due to weather, nighttime), acoustic monitoring may be 
used to allow certain activities to occur, as further detailed below.
    PAM would take place in addition to the visual monitoring program. 
Visual monitoring typically is not effective during periods of poor 
visibility or at night, and even with good visibility, is unable to 
detect marine mammals when they are below the surface or beyond visual 
range. Acoustic monitoring can be used in addition to visual 
observations to improve detection, identification, and localization of 
cetaceans. The acoustic monitoring would serve to alert visual PSOs (if 
on duty) when vocalizing cetaceans are detected. It is only useful when 
marine mammals vocalize, but it can be effective either by day or by 
night, and does not depend on good visibility. It would be monitored in 
real time so that the visual observers can be advised when cetaceans 
are detected.
    The R/V Langseth will use a towed PAM system, which must be 
monitored by at a minimum one on duty acoustic PSO beginning at least 
30 minutes prior to ramp-up and at all times during use of the acoustic 
source. Acoustic PSOs may be on watch for a maximum of 4 consecutive 
hours followed by a break of at least one hour between watches and may 
conduct a maximum of 12 hours of observation per 24-hour period. 
Combined observational duties (acoustic and visual but not at same 
time) may not exceed 12 hours per 24-hour period for any individual 
PSO.
    Survey activity may continue for 30 minutes when the PAM system 
malfunctions or is damaged, while the PAM operator diagnoses the issue. 
If the diagnosis indicates that the PAM system must be repaired to 
solve the problem, operations may continue for an additional 5 hours 
without acoustic monitoring during daylight hours only under the 
following conditions:
     Sea state is less than or equal to BSS 4;
     No marine mammals (excluding delphinids) detected solely 
by PAM in the applicable EZ in the previous 2 hours;
     NMFS is notified via email as soon as practicable with the 
time and location in which operations began occurring without an active 
PAM system; and
     Operations with an active acoustic source, but without an 
operating PAM system, do not exceed a cumulative total of 5 hours in 
any 24-hour period.

Establishment of Exclusion and Pre-Start Clearance Zones

    An EZ is a defined area within which occurrence of a marine mammal 
triggers mitigation action intended to reduce the potential for certain 
outcomes, e.g., auditory injury, disruption of critical behaviors. The 
PSOs would establish a minimum EZ with a 500-m radius. The 500-m EZ 
would be based on radial distance from the edge of the airgun array 
(rather than being based on the center of the array or around the 
vessel itself). With certain exceptions (described below), if a marine 
mammal appears within or enters this zone, the acoustic source would be 
shut down.
    The pre-start clearance zone is defined as the area that must be 
clear of marine mammals prior to beginning ramp-up of the acoustic 
source, and includes the EZ plus the buffer zone. Detections of marine 
mammals within the pre-start clearance zone would prevent airgun 
operations from beginning (i.e., ramp-up).
    The 500-m EZ is intended to be precautionary in the sense that it 
would be expected to contain sound exceeding the injury criteria for 
all cetacean hearing groups, (based on the dual criteria of 
SELcum and peak SPL), while also providing a consistent, 
reasonably observable zone within which PSOs would typically be able to 
conduct effective observational effort. Additionally, a 500-m EZ is 
expected to minimize the likelihood that marine mammals will be exposed 
to levels likely to result in more severe behavioral responses. 
Although significantly greater distances may be observed from an 
elevated platform under good conditions, we believe that 500 m is 
likely regularly attainable for PSOs using the naked eye during typical 
conditions. The pre-start clearance zone simply represents the addition 
of a buffer to the EZ, doubling the EZ size during pre-clearance.
    An extended EZ of 1,500 m must be enforced for all beaked whales. 
No buffer of this extended EZ is required.

Pre-Start Clearance and Ramp-Up

    Ramp-up (sometimes referred to as ``soft start'') means the gradual 
and systematic increase of emitted sound levels from an airgun array. 
Ramp-up begins by first activating a single airgun of the smallest 
volume, followed by doubling the number of active elements

[[Page 30026]]

in stages until the full complement of an array's airguns are active. 
Each stage should be approximately the same duration, and the total 
duration should not be less than approximately 20 minutes. The intent 
of pre-start clearance observation (30 minutes) is to ensure no 
protected species are observed within the pre-clearance zone (or 
extended EZ, for beaked whales) prior to the beginning of ramp-up. 
During pre-start clearance period is the only time observations of 
marine mammals in the buffer zone would prevent operations (i.e., the 
beginning of ramp-up). The intent of ramp-up is to warn marine mammals 
of pending seismic operations and to allow sufficient time for those 
animals to leave the immediate vicinity. A ramp-up procedure, involving 
a step-wise increase in the number of airguns firing and total array 
volume until all operational airguns are activated and the full volume 
is achieved, is required at all times as part of the activation of the 
acoustic source. All operators must adhere to the following pre-start 
clearance and ramp-up requirements:
     The operator must notify a designated PSO of the planned 
start of ramp-up as agreed upon with the lead PSO; the notification 
time should not be less than 60 minutes prior to the planned ramp-up in 
order to allow the PSOs time to monitor the pre-start clearance zone 
(and extended EZ) for 30 minutes prior to the initiation of ramp-up 
(pre-start clearance);
     Ramp-ups shall be scheduled so as to minimize the time 
spent with the source activated prior to reaching the designated run-
in;
     One of the PSOs conducting pre-start clearance 
observations must be notified again immediately prior to initiating 
ramp-up procedures and the operator must receive confirmation from the 
PSO to proceed;
     Ramp-up may not be initiated if any marine mammal is 
within the applicable exclusion or buffer zone. If a marine mammal is 
observed within the pre-start clearance zone (or extended EZ, for 
beaked whales) during the 30 minute pre-start clearance period, ramp-up 
may not begin until the animal(s) has been observed exiting the zones 
or until an additional time period has elapsed with no further 
sightings (15 minutes for small odontocetes and pinnipeds, and 30 
minutes for all mysticetes and all other odontocetes, including sperm 
whales, beaked whales, and large delphinids, such as killer whales);
     Ramp-up shall begin by activating a single airgun of the 
smallest volume in the array and shall continue in stages by doubling 
the number of active elements at the commencement of each stage, with 
each stage of approximately the same duration. Duration shall not be 
less than 20 minutes. The operator must provide information to the PSO 
documenting that appropriate procedures were followed;
     PSOs must monitor the pre-start clearance zone (and 
extended EZ) during ramp-up, and ramp-up must cease and the source must 
be shut down upon detection of a marine mammal within the applicable 
zone. Once ramp-up has begun, detections of marine mammals within the 
buffer zone do not require shutdown, but such observation shall be 
communicated to the operator to prepare for the potential shutdown;
     Ramp-up may occur at times of poor visibility, including 
nighttime, if appropriate acoustic monitoring has occurred with no 
detections in the 30 minutes prior to beginning ramp-up. Acoustic 
source activation may only occur at times of poor visibility where 
operational planning cannot reasonably avoid such circumstances;
     If the acoustic source is shut down for brief periods 
(i.e., less than 30 minutes) for reasons other than that described for 
shutdown (e.g., mechanical difficulty), it may be activated again 
without ramp-up if PSOs have maintained constant visual and/or acoustic 
observation and no visual or acoustic detections of marine mammals have 
occurred within the applicable EZ. For any longer shutdown, pre-start 
clearance observation and ramp-up are required. For any shutdown at 
night or in periods of poor visibility (e.g., BSS 4 or greater), ramp-
up is required, but if the shutdown period was brief and constant 
observation was maintained, pre-start clearance watch of 30 minutes is 
not required; and
     Testing of the acoustic source involving all elements 
requires ramp-up. Testing limited to individual source elements or 
strings does not require ramp-up but does require pre-start clearance 
of 30 min.

Shutdown

    The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array. Any PSO on 
duty will have the authority to delay the start of survey operations or 
to call for shutdown of the acoustic source if a marine mammal is 
detected within the applicable EZ. The operator must also establish and 
maintain clear lines of communication directly between PSOs on duty and 
crew controlling the acoustic source to ensure that shutdown commands 
are conveyed swiftly while allowing PSOs to maintain watch. When both 
visual and acoustic PSOs are on duty, all detections will be 
immediately communicated to the remainder of the on-duty PSO team for 
potential verification of visual observations by the acoustic PSO or of 
acoustic detections by visual PSOs. When the airgun array is active 
(i.e., anytime one or more airguns is active, including during ramp-up) 
and (1) a marine mammal appears within or enters the applicable EZ and/
or (2) a marine mammal (other than delphinids, see below) is detected 
acoustically and localized within the applicable EZ, the acoustic 
source will be shut down. When shutdown is called for by a PSO, the 
acoustic source will be immediately deactivated and any dispute 
resolved only following deactivation. Additionally, shutdown will occur 
whenever PAM alone (without visual sighting), confirms presence of 
marine mammal(s) in the EZ. If the acoustic PSO cannot confirm presence 
within the EZ, visual PSOs will be notified but shutdown is not 
required.
    Following a shutdown, airgun activity would not resume until the 
marine mammal has cleared the EZ. The animal would be considered to 
have cleared the EZ if it is visually observed to have departed the EZ 
(i.e., animal is not required to fully exit the buffer zone where 
applicable), or it has not been seen within the EZ for 15 minutes for 
small odontocetes and pinnipeds, or 30 minutes for all mysticetes and 
all other odontocetes, including sperm whales, beaked whales, and large 
delphinids, such as killer whales.
    The shutdown requirement can be waived for small dolphins if an 
individual is detected within the EZ. As defined here, the small 
dolphin group is intended to encompass those members of the Family 
Delphinidae most likely to voluntarily approach the source vessel for 
purposes of interacting with the vessel and/or airgun array (e.g., bow 
riding). This exception to the shutdown requirement applies solely to 
specific genera of small dolphins (Lagenorhynchus and Lissodelphis).
    We include this small dolphin exception because shutdown 
requirements for small dolphins under all circumstances represent 
practicability concerns without likely commensurate benefits for the 
animals in question. Small dolphins are generally the most commonly 
observed marine mammals in the specific geographic region and would 
typically be the only marine mammals likely to intentionally approach 
the vessel. As described above, auditory injury is extremely unlikely 
to occur for mid-frequency cetaceans (e.g., delphinids),

[[Page 30027]]

as this group is relatively insensitive to sound produced at the 
predominant frequencies in an airgun pulse while also having a 
relatively high threshold for the onset of auditory injury (i.e., 
permanent threshold shift).
    A large body of anecdotal evidence indicates that small dolphins 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinoids (e.g., Barkaszi et al., 2012, 2018). The potential 
for increased shutdowns resulting from such a measure would require the 
Langseth to revisit the missed track line to reacquire data, resulting 
in an overall increase in the total sound energy input to the marine 
environment and an increase in the total duration over which the survey 
is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large delphinids) are no more likely to incur 
auditory injury than are small dolphins, they are much less likely to 
approach vessels. Therefore, retaining a shutdown requirement for large 
delphinids would not have similar impacts in terms of either 
practicability for the applicant or corollary increase in sound energy 
output and time on the water. We do anticipate some benefit for a 
shutdown requirement for large delphinids in that it simplifies 
somewhat the total range of decision-making for PSOs and may preclude 
any potential for physiological effects other than to the auditory 
system as well as some more severe behavioral reactions for any such 
animals in close proximity to the source vessel.
    Visual PSOs shall use best professional judgment in making the 
decision to call for a shutdown if there is uncertainty regarding 
identification (i.e., whether the observed marine mammal(s) belongs to 
one of the delphinid genera for which shutdown is waived or one of the 
species with a larger EZ).
    L-DEO must implement shutdown if a marine mammal species for which 
take was not authorized, or a species for which authorization was 
granted but the takes have been met, approaches the Level A or Level B 
harassment zones. L-DEO must also implement shutdown if any of the 
following are observed at any distance:
     Any large whale (defined as a sperm whale or any mysticete 
species) with a calf (defined as an animal less than two-thirds the 
body size of an adult observed to be in close association with an 
adult);
     An aggregation of six or more large whales; and/or
     A North Pacific right whale.

Vessel Strike Avoidance

    1. Vessel operators and crews must maintain a vigilant watch for 
all protected species and slow down, stop their vessel, or alter 
course, as appropriate and regardless of vessel size, to avoid striking 
any marine mammal. A visual observer aboard the vessel must monitor a 
vessel strike avoidance zone around the vessel (distances stated 
below). Visual observers monitoring the vessel strike avoidance zone 
may be third-party observers (i.e., PSOs) or crew members, but crew 
members responsible for these duties must be provided sufficient 
training to 1) distinguish marine mammals from other phenomena and 2) 
broadly to identify a marine mammal as a right whale, other whale 
(defined in this context as sperm whales or baleen whales other than 
right whales), or other marine mammal.
    2. Vessel speeds must also be reduced to 10 kn or less when mother/
calf pairs, pods, or large assemblages of cetaceans are observed near a 
vessel.
    3. All vessels must maintain a minimum separation distance of 500 m 
from right whales. If a whale is observed but cannot be confirmed as a 
species other than a right whale, the vessel operator must assume that 
it is a right whale and take appropriate action.
    4. All vessels must maintain a minimum separation distance of 100 m 
from sperm whales and all other baleen whales.
    5. All vessels must, to the maximum extent practicable, attempt to 
maintain a minimum separation distance of 50 m from all other marine 
mammals, with an understanding that at times this may not be possible 
(e.g., for animals that approach the vessel).
    6. When marine mammals are sighted while a vessel is underway, the 
vessel shall take action as necessary to avoid violating the relevant 
separation distance (e.g., attempt to remain parallel to the animal's 
course, avoid excessive speed or abrupt changes in direction until the 
animal has left the area). If marine mammals are sighted within the 
relevant separation distance, the vessel must reduce speed and shift 
the engine to neutral, not engaging the engines until animals are clear 
of the area. This does not apply to any vessel towing gear or any 
vessel that is navigationally constrained.
    7. These requirements do not apply in any case where compliance 
would create an imminent and serious threat to a person or vessel or to 
the extent that a vessel is restricted in its ability to maneuver and, 
because of the restriction, cannot comply.
    We have carefully evaluated the suite of mitigation measures 
described here and considered a range of other measures in the context 
of ensuring that we prescribe the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. Based on our evaluation of the proposed 
measures, as well as other measures considered by NMFS described above, 
NMFS has preliminarily determined that the mitigation measures provide 
the means of effecting the least practicable impact on the affected 
species or stocks and their habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance.

Mitigation Measures in Canadian Waters

    As stated previously, NMFS cannot authorize the incidental take of 
marine mammals in the territorial seas of foreign nations, as the MMPA 
does not apply in those waters. L-DEO is required to adhere to the 
mitigation measures described above while operating within the U.S. EEZ 
and Canadian EEZ. The requirements do not apply within Canadian 
territorial waters. NMFS expects that DFO may prescribe mitigation 
measures that would apply to L-DEO's survey operations within the 
Canadian EEZ and Canadian territorial waters but is currently unaware 
of the specifics of any potential measures. While operating within the 
Canadian EEZ but outside Canadian territorial waters, if mitigation 
requirements prescribed by NMFS differ from the requirements 
established under Canadian law, L-DEO would adhere to the most 
protective measure. For operations in Canadian territorial waters, L-
DEO would implement measures required under Canadian law (if any). If 
information regarding measures required under Canadian law becomes 
available prior to NMFS' final decision on this request for IHA, NMFS 
will consider it as appropriate in making its negligible impact 
determination.

Proposed Monitoring and Reporting

    In order to issue an IHA 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 
authorizations 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

[[Page 30028]]

mammals that are expected to be present in the proposed action area. 
Effective reporting is critical both to compliance as well as ensuring 
that the most value is obtained from the required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Vessel-Based Visual Monitoring

    As described above, PSO observations would take place during 
daytime airgun operations. During seismic operations, at least five 
visual PSOs would be based aboard the Langseth. Two visual PSOs would 
be on duty at all time during daytime hours. Monitoring shall be 
conducted in accordance with the following requirements:
     The operator shall provide PSOs with bigeye binoculars 
(e.g., 25 x 150; 2.7 view angle; individual ocular focus; height 
control) of appropriate quality (i.e., Fujinon or equivalent) solely 
for PSO use. These shall be pedestal-mounted on the deck at the most 
appropriate vantage point that provides for optimal sea surface 
observation, PSO safety, and safe operation of the vessel; and
     The operator will work with the selected third-party 
observer provider to ensure PSOs have all equipment (including backup 
equipment) needed to adequately perform necessary tasks, including 
accurate determination of distance and bearing to observed marine 
mammals.
    PSOs must have the following requirements and qualifications:
     PSOs shall be independent, dedicated, trained visual and 
acoustic PSOs and must be employed by a third-party observer provider;
     PSOs shall have no tasks other than to conduct 
observational effort (visual or acoustic), collect data, and 
communicate with and instruct relevant vessel crew with regard to the 
presence of protected species and mitigation requirements (including 
brief alerts regarding maritime hazards);
     PSOs shall have successfully completed an approved PSO 
training course appropriate for their designated task (visual or 
acoustic). Acoustic PSOs are required to complete specialized training 
for operating PAM systems and are encouraged to have familiarity with 
the vessel with which they will be working;
     PSOs can act as acoustic or visual observers (but not at 
the same time) as long as they demonstrate that their training and 
experience are sufficient to perform the task at hand;
     NMFS must review and approve PSO resumes accompanied by a 
relevant training course information packet that includes the name and 
qualifications (i.e., experience, training completed, or educational 
background) of the instructor(s), the course outline or syllabus, and 
course reference material as well as a document stating successful 
completion of the course;
     NMFS shall have one week to approve PSOs from the time 
that the necessary information is submitted, after which PSOs meeting 
the minimum requirements shall automatically be considered approved;
     PSOs must successfully complete relevant training, 
including completion of all required coursework and passing (80 percent 
or greater) a written and/or oral examination developed for the 
training program;
     PSOs must have successfully attained a bachelor's degree 
from an accredited college or university with a major in one of the 
natural sciences, a minimum of 30 semester hours or equivalent in the 
biological sciences, and at least one undergraduate course in math or 
statistics; and
     The educational requirements may be waived if the PSO has 
acquired the relevant skills through alternate experience. Requests for 
such a waiver shall be submitted to NMFS and must include written 
justification. Requests shall be granted or denied (with justification) 
by NMFS within one week of receipt of submitted information. Alternate 
experience that may be considered includes, but is not limited to (1) 
secondary education and/or experience comparable to PSO duties; (2) 
previous work experience conducting academic, commercial, or 
government-sponsored protected species surveys; or (3) previous work 
experience as a PSO; the PSO should demonstrate good standing and 
consistently good performance of PSO duties.
    For data collection purposes, PSOs shall use standardized data 
collection forms, whether hard copy or electronic. PSOs shall record 
detailed information about any implementation of mitigation 
requirements, including the distance of animals to the acoustic source 
and description of specific actions that ensued, the behavior of the 
animal(s), any observed changes in behavior before and after 
implementation of mitigation, and if shutdown was implemented, the 
length of time before any subsequent ramp-up of the acoustic source. If 
required mitigation was not implemented, PSOs should record a 
description of the circumstances. At a minimum, the following 
information must be recorded:
     Vessel names (source vessel and other vessels associated 
with survey) and call signs;
     PSO names and affiliations;
     Dates of departures and returns to port with port name;
     Date and participants of PSO briefings;
     Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort;
     Vessel location (latitude/longitude) when survey effort 
began and ended and vessel location at beginning and end of visual PSO 
duty shifts;
     Vessel heading and speed at beginning and end of visual 
PSO duty shifts and upon any line change;
     Environmental conditions while on visual survey (at 
beginning and end of PSO shift and whenever conditions changed 
significantly), including BSS and any other relevant weather conditions 
including cloud cover, fog, sun glare, and overall visibility to the 
horizon;
     Factors that may have contributed to impaired observations 
during each PSO shift change or as needed as environmental conditions 
changed (e.g., vessel traffic, equipment malfunctions); and

[[Page 30029]]

     Survey activity information, such as acoustic source power 
output while in operation, number and volume of airguns operating in 
the array, tow depth of the array, and any other notes of significance 
(i.e., pre-start clearance, ramp-up, shutdown, testing, shooting, ramp-
up completion, end of operations, streamers, etc.).
    The following information should be recorded upon visual 
observation of any protected species:
     Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
     PSO who sighted the animal;
     Time of sighting;
     Vessel location at time of sighting;
     Water depth;
     Direction of vessel's travel (compass direction);
     Direction of animal's travel relative to the vessel;
     Pace of the animal;
     Estimated distance to the animal and its heading relative 
to vessel at initial sighting;
     Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified) and the composition of the 
group if there is a mix of species;
     Estimated number of animals (high/low/best);
     Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
     Description (as many distinguishing features as possible 
of each individual seen, including length, shape, color, pattern, scars 
or markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
     Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding, 
traveling; as explicit and detailed as possible; note any observed 
changes in behavior);
     Animal's closest point of approach (CPA) and/or closest 
distance from any element of the acoustic source;
     Platform activity at time of sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other); and
     Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up) and time and location of the 
action.
    If a marine mammal is detected while using the PAM system, the 
following information should be recorded:
     An acoustic encounter identification number, and whether 
the detection was linked with a visual sighting;
     Date and time when first and last heard;
     Types and nature of sounds heard (e.g., clicks, whistles, 
creaks, burst pulses, continuous, sporadic, strength of signal); and
     Any additional information recorded such as water depth of 
the hydrophone array, bearing of the animal to the vessel (if 
determinable), species or taxonomic group (if determinable), 
spectrogram screenshot, and any other notable information.

Reporting

    A report would be submitted to NMFS within 90 days after the end of 
the cruise. The report would summarize the dates and locations of 
seismic operations, and all marine mammal sightings (dates, times, 
locations, activities, associated seismic survey activities), and 
provide full documentation of methods, results, and interpretation 
pertaining to all monitoring.
    The draft report shall also include geo-referenced time-stamped 
vessel tracklines for all time periods during which airguns were 
operating. Tracklines should include points recording any change in 
airgun status (e.g., when the airguns began operating, when they were 
turned off, or when they changed from full array to single gun or vice 
versa). GIS files shall be provided in ESRI shapefile format and 
include the UTC date and time, latitude in decimal degrees, and 
longitude in decimal degrees. All coordinates shall be referenced to 
the WGS84 geographic coordinate system. In addition to the report, all 
raw observational data shall be made available to NMFS. The report must 
summarize the data collected as described above and in the IHA. A final 
report must be submitted within 30 days following resolution of any 
comments on the draft report.

Reporting Injured or Dead Marine Mammals

    Discovery of injured or dead marine mammals--In the event that 
personnel involved in survey activities covered by the authorization 
discover an injured or dead marine mammal, the L-DEO shall report the 
incident to the Office of Protected Resources (OPR), NMFS and to the 
NMFS Alaska Regional Stranding Coordinator as soon as feasible. The 
report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.
    Vessel strike--In the event of a ship strike of a marine mammal by 
any vessel involved in the activities covered by the authorization, L-
DEO shall report the incident to OPR, NMFS and to the NMFS Alaska 
Regional Stranding Coordinator as soon as feasible. The report must 
include the following information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Vessel's speed during and leading up to the incident;
     Vessel's course/heading and what operations were being 
conducted (if applicable);
     Status of all sound sources in use;
     Description of avoidance measures/requirements that were 
in place at the time of the strike and what additional measure were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
     Species identification (if known) or description of the 
animal(s) involved;
     Estimated size and length of the animal that was struck;
     Description of the behavior of the animal immediately 
preceding and following the strike;
     If available, description of the presence and behavior of 
any other marine mammals present immediately preceding the strike;
     Estimated fate of the animal (e.g., dead, injured but 
alive, injured and moving, blood or tissue observed in the water, 
status unknown, disappeared); and
     To the extent practicable, photographs or video footage of 
the animal(s).

Actions To Minimize Additional Harm To Live-Stranded (or Milling) 
Marine Mammals

    In the event of a live stranding (or near-shore atypical milling) 
event within 50 km of the survey operations, where the NMFS stranding 
network is engaged in herding or other interventions to return animals 
to the water, the Director of OPR, NMFS (or designee) will advise L-DEO 
of the need to implement shutdown for all active acoustic sources 
operating within 50 km of the stranding. Procedures related to 
shutdowns for live stranding or milling marine mammals include the 
following:
     If at any time, the marine mammal(s) die or are 
euthanized, or if

[[Page 30030]]

herding/intervention efforts are stopped, the Director of OPR, NMFS (or 
designee) will advise L-DEO that the shutdown around the animals' 
location is no longer needed.
     Otherwise, shutdown procedures will remain in effect until 
the Director of OPR, NMFS (or designee) determines and advises L-DEO 
that all live animals involved have left the area (either of their own 
volition or following an intervention).
     If further observations of the marine mammals indicate the 
potential for re-stranding, additional coordination with L-DEO will be 
required to determine what measures are necessary to minimize that 
likelihood (e.g., extending the shutdown or moving operations farther 
away) and to implement those measures as appropriate.
    Additional Information Requests--If NMFS determines that the 
circumstances of any marine mammal stranding found in the vicinity of 
the activity suggest investigation of the association with survey 
activities is warranted, and an investigation into the stranding is 
being pursued, NMFS will submit a written request to L-DEO indicating 
that the following initial available information must be provided as 
soon as possible, but no later than 7 business days after the request 
for information:
     Status of all sound source use in the 48 hours preceding 
the estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
     If available, description of the behavior of any marine 
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and 
immediately after the discovery of the stranding.
    In the event that the investigation is still inconclusive, the 
investigation of the association of the survey activities is still 
warranted, and the investigation is still being pursued, NMFS may 
provide additional information requests, in writing, regarding the 
nature and location of survey operations prior to the time period 
above.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact 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 (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    To avoid repetition, our analysis applies to all species listed in 
Table 1, given that NMFS expects the anticipated effects of the planned 
geophysical survey to be similar in nature. Where there are meaningful 
differences between species or stocks, or groups of species, in 
anticipated individual responses to activities, impact of expected take 
on the population due to differences in population status, or impacts 
on habitat, NMFS has identified species-specific factors to inform the 
analysis.
    As described above, we propose to authorize only the takes 
estimated to occur outside of Canadian territorial waters (Table 7); 
however, for the purposes of our negligible impact analysis and 
determination, we consider the total number of takes that are 
anticipated to occur as a result of the entire survey (including the 
portion of the survey that would occur within the Canadian territorial 
waters (approximately 13 percent of the survey) (Table 8).

                       Table 8--Total Estimated Take Including Canadian Territorial Waters
----------------------------------------------------------------------------------------------------------------
                                      Level B      Level A
                                     harassment   harassment    Level B      Level A
                                     (excluding   (excluding   harassment   harassment     Total        Total
              Species                 Canadian     Canadian    (Canadian    (Canadian     Level B      Level A
                                    territorial  territorial  territorial  territorial   harassment   harassment
                                       waters)      waters)      waters)      waters)
----------------------------------------------------------------------------------------------------------------
Gray whale, WNP...................            2            0            1            0            3            0
Gray whale, ENP...................        1,448           45          666           16        2,114           61
Humpback whale....................          403           14          165            4          568           18
Blue whale........................           31            1            4            0           35            1
Fin whale.........................          873           44           69            1          942           45
Sei whale.........................           34            1            7            0           41            1
Minke whale.......................           57            2           14            0           71            2
Sperm whale.......................          131            0           22            0          153            0
Baird's beaked whale..............           29            0            2            0           31            0
Stejneger's beaked whale..........          120            0            9            0          129            0
Cuvier's beaked whale.............          114            0            9            0          123            0
Pacific white-sided dolphin.......        1,374            0          191            0        1,565            0
Northern right whale dolphin......          927            0          451            0        1,378            0
Risso's dolphin...................           22            0           22            0           44            0
Killer whale......................          290            0           89            0          379            0
Dall's porpoise...................        5,661          178        1,825           36        7,486          214
Harbor porpoise...................          990           26          455            9        1,445           35
Northern fur seal.................        5,812            0        1,213            0        7,025            0
California sea lion...............        1,258            0          433            0        1,691            0
Steller sea lion, wDPS............           54            0           55            0          109            0
Steller sea lion, eDPS............        2,381            0        2,467            0        4,848            0
Northern elephant seal............        6,850            0        1,429            0        8,279            0
Harbor seal.......................        6,012            0        6,228            0       12,240            0
----------------------------------------------------------------------------------------------------------------


[[Page 30031]]

    NMFS does not anticipate that serious injury or mortality would 
occur as a result of L-DEO's planned survey, even in the absence of 
mitigation, and none would be authorized. Similarly, non-auditory 
physical effects, stranding, and vessel strike are not expected to 
occur.
    We are proposing to authorize a limited number of instances of 
Level A harassment of seven species (low- and high-frequency cetacean 
hearing groups only) and Level B harassment only of the remaining 
marine mammal species. However, we believe that any PTS incurred in 
marine mammals as a result of the planned activity would be in the form 
of only a small degree of PTS, not total deafness, because of the 
constant movement of both the R/V Langseth and of the marine mammals in 
the project areas, as well as the fact that the vessel is not expected 
to remain in any one area in which individual marine mammals would be 
expected to concentrate for an extended period of time. Since the 
duration of exposure to loud sounds will be relatively short it would 
be unlikely to affect the fitness of any individuals. Also, as 
described above, we expect that marine mammals would likely move away 
from a sound source that represents an aversive stimulus, especially at 
levels that would be expected to result in PTS, given sufficient notice 
of the R/V Langseth's approach due to the vessel's relatively low speed 
when conducting seismic surveys. We expect that the majority of takes 
would be in the form of short-term Level B behavioral harassment in the 
form of temporary avoidance of the area or decreased foraging (if such 
activity were occurring), reactions that are considered to be of low 
severity and with no lasting biological consequences (e.g., Southall et 
al., 2007, Ellison et al., 2012).
    Marine mammal habitat may be impacted by elevated sound levels, but 
these impacts would be temporary. Prey species are mobile and are 
broadly distributed throughout the project areas; therefore, marine 
mammals that may be temporarily displaced during survey activities are 
expected to be able to resume foraging once they have moved away from 
areas with disturbing levels of underwater noise. Because of the 
relatively short duration (27 days) and temporary nature of the 
disturbance, the availability of similar habitat and resources in the 
surrounding area, the impacts to marine mammals and the food sources 
that they utilize are not expected to cause significant or long-term 
consequences for individual marine mammals or their populations.
    The tracklines of this survey either traverse or are proximal to 
critical habitat for the Mexico DPS of humpback whales and for Steller 
sea lions, and to feeding BIAs for humpback whales in general 
(including both the Hawaii and Mexico DPSs/Central North Pacific stock 
whales that are anticipated to occur in the survey area). As described 
previously, the survey area is near a feeding BIA for gray whales and 
covers the gray whale migratory BIA. However, these BIAs would not be 
affected as they are spatially and temporally separated, respectively, 
from the survey.
    Yazvenko et al. (2007) reported no apparent changes in the 
frequency of feeding activity in Western gray whales exposed to airgun 
sounds in their feeding grounds near Sakhalin Island. Goldbogen et al. 
(2013) found blue whales feeding on highly concentrated prey in shallow 
depths (such as the conditions expected within humpback feeding BIAs) 
were less likely to respond and cease foraging than whales feeding on 
deep, dispersed prey when exposed to simulated sonar sources, 
suggesting that the benefits of feeding for humpbacks foraging on high-
density prey may outweigh perceived harm from the acoustic stimulus, 
such as the seismic survey (Southall et al., 2016). Additionally, L-DEO 
will shut down the airgun array upon observation of an aggregation of 
six or more large whales, which would reduce impacts to cooperatively 
foraging animals. For all habitats, no physical impacts to habitat are 
anticipated from seismic activities. While SPLs of sufficient strength 
have been known to cause injury to fish and fish and invertebrate 
mortality, in feeding habitats, the most likely impact to prey species 
from survey activities would be temporary avoidance of the affected 
area and any injury or mortality of prey species would be localized 
around the survey and not of a degree that would adversely impact 
marine mammal foraging. The duration of fish avoidance of a given area 
after survey effort stops is unknown, but a rapid return to normal 
recruitment, distribution and behavior is expected. Given the short 
operational seismic time near or traversing important habitat areas, as 
well as the ability of cetaceans and prey species to move away from 
acoustic sources, NMFS expects that there would be, at worst, minimal 
impacts to animals and habitat within these areas.
    Critical habitat for Steller sea lions has been established at 
three rookeries in southeast Alaska (Hazy Island, White Sisters Island, 
and Forrester Island near Dixon Entrance), at several major haul-outs, 
and including aquatic zones that extend 0.9 km seaward and air zones 
extending 0.9 km above the rookeries. Steller sea lions occupy 
rookeries and pup from late-May through early-July (NMFS. 2008), 
indicating that L-DEO's survey is unlikely to impact important sea lion 
behaviors in critical habitat. Impacts to Steller sea lions within 
these areas, and throughout the survey area, as well as impacts to 
other pinniped species, are expected to be limited to short-term 
behavioral disturbance, with no lasting biological consequences.

Negligible Impact Conclusions

    The proposed survey would be of short duration (27 days of seismic 
operations), and the acoustic ``footprint'' of the proposed survey 
would be small relative to the ranges of the marine mammals that would 
potentially be affected. Sound levels would increase in the marine 
environment in a relatively small area surrounding the vessel compared 
to the range of the marine mammals within the proposed survey area. 
Short term exposures to survey operations are not likely to 
significantly disrupt marine mammal behavior, and the potential for 
longer-term avoidance of important areas is limited.
    The proposed mitigation measures are expected to reduce the number 
and/or severity of takes by allowing for detection of marine mammals in 
the vicinity of the vessel by visual and acoustic observers, and by 
minimizing the severity of any potential exposures via shutdowns of the 
airgun array. Based on previous monitoring reports for substantially 
similar activities that have been previously authorized by NMFS, we 
expect that the proposed mitigation will be effective in preventing, at 
least to some extent, potential PTS in marine mammals that may 
otherwise occur in the absence of the proposed mitigation (although all 
authorized PTS has been accounted for in this analysis).
    NMFS concludes that exposures to marine mammal species and stocks 
due to L-DEO's proposed survey would result in only short-term 
(temporary and short in duration) effects to individuals exposed, over 
relatively small areas of the affected animals' ranges. Animals may 
temporarily avoid the immediate area, but are not expected to 
permanently abandon the area. Major shifts in habitat use, 
distribution, or foraging success are not expected. NMFS does not 
anticipate the proposed take estimates to impact annual rates of 
recruitment or survival.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the

[[Page 30032]]

species or stock through effects on annual rates of recruitment or 
survival:
     No serious injury or mortality is anticipated or proposed 
to be authorized;
     The proposed activity is temporary and of relatively short 
duration (27 days);
     The anticipated impacts of the proposed activity on marine 
mammals would primarily be temporary behavioral changes due to 
avoidance of the area around the survey vessel;
     The number of instances of potential PTS that may occur 
are expected to be very small in number. Instances of potential PTS 
that are incurred in marine mammals are expected to be of a low level, 
due to constant movement of the vessel and of the marine mammals in the 
area, and the nature of the survey design (not concentrated in areas of 
high marine mammal concentration);
     The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the proposed survey to avoid exposure to sounds from the activity;
     The potential adverse effects on fish or invertebrate 
species that serve as prey species for marine mammals from the proposed 
survey would be temporary and spatially limited, and impacts to marine 
mammal foraging would be minimal; and
     The proposed mitigation measures, including visual and 
acoustic monitoring and shutdowns are expected to minimize potential 
impacts to marine mammals (both amount and severity).
    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 proposed mitigation and 
monitoring measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    There are several stocks for which the estimated instances of take 
appear high when compared to the stock abundance (Table 7), or for 
which there is no currently accepted stock abundance estimate. These 
include the fin whale, minke whale, sperm whale, three species of 
beaked whale, four stocks of killer whales, harbor porpoise, and one 
stock of harbor seal. However, when other qualitative factors are used 
to inform an assessment of the likely number of individual marine 
mammals taken, the resulting numbers are appropriately considered 
small. We discuss these in further detail below.
    For all other stocks (aside from those referenced above and 
discussed below), the proposed take is less than one-third of the best 
available stock abundance (recognizing that some of those takes may be 
repeats of the same individual, thus rendering the actual percentage 
even lower), and noting that we generally excluded consideration of 
abundance information for British Columbia in considering the amount of 
take relative to the best available stock abundance information.
    The stock abundance estimates for the fin, minke, beaked, and sperm 
whale stocks that occur in the survey area are unknown, according to 
the latest SARs. The same is true for the harbor porpoise. Therefore, 
we reviewed other scientific information in making our small numbers 
determinations for these species. As noted previously, partial 
abundance estimates of 1,233 and 2,020 minke whales are available for 
shelf and nearshore waters between the Kenai Peninsula and Amchitka 
Pass and for the eastern Bering Sea shelf, respectively. For the minke 
whale, these partial abundance estimates alone are sufficient to 
demonstrate that the proposed take number of 59 is of small numbers. 
The same surveys produced partial abundance estimates of 1,652 and 
1,061 fin whales, for the same areas, respectively. Considering these 
two partial abundance estimates in conjunction with the British 
Columbia abundance estimate of 329 whales produces a total partial 
estimate of 3,042 whales for shelf and nearshore waters between the 
Kenai Peninsula and Amchitka Pass, the eastern Bering Sea shelf, and 
British Columbia. Given that the Northeast Pacific stock of fin whale's 
range is described as covering the entire GOA and Bering Sea, we 
reasonably assume that a total abundance estimate for the stock would 
show that the take number proposed for authorization (917) is small. In 
addition, for these stocks as well as for other stocks discussed below 
whose range spans the GOA, given that the estimated take will take 
place in a relatively small portion of the stock's range, it is likely 
there would be repeat takes of a smaller number of individuals, and 
therefore, the number of individual animals taken will be lower.
    As noted previously, Kato and Miyashita (1998) produced an 
abundance estimate of 102,112 sperm whales in the western North 
Pacific. However, this estimate is believed to be positively biased. We 
therefore refer to Barlow and Taylor (2005)'s estimate of 26,300 sperm 
whales in the northeast temperate Pacific to demonstrate that the 
proposed take number of 136 is a small number. There is no abundance 
information available for any Alaskan stock of beaked whale. However, 
the take numbers are sufficiently small (ranging from 29-120) that we 
can safely assume that they are small relative to any reasonable 
assumption of likely population abundance for these stocks. As an 
example, we review available abundance information for other stocks of 
Cuvier's beaked whales, which is widely distributed throughout deep 
waters of all oceans and is typically the most commonly encountered 
beaked whale in its range. Where some degree of bias correction, which 
is critical to an accurate abundance estimate for cryptic species like 
beaked whales, is incorporated to the estimate, we see typical 
estimates in the thousands of animals, demonstrating that the take 
numbers proposed for authorization are reasonably considered small. 
Current abundance estimates include the Western North Atlantic stock 
(5,744 animals; CV = 0.36), the Hawaii Pelagic stock (4,431 animals, CV 
= 0.41), and the California/Oregon/Washington stock (3,274 animals; CV 
= 0.67).
    For the southeast Alaska stock of harbor porpoise, whose range is 
defined as from Dixon Entrance to Cape Suckling (including inland 
waters), the SAR describes a partial abundance estimate, covering 
inland waters but not coastal waters, totaling 1,354 porpoise. This 
most recent abundance estimate is based on survey effort in inland 
waters during 2010-12 (Dahlheim et al., 2015). An older abundance 
estimate, based on survey effort conducted in 1997, covering both 
coastal and inland waters of the stock's range, provides a more 
complete abundance estimate of 11,146 animals (Hobbs and Waite, 2010). 
This

[[Page 30033]]

estimate is sufficient to demonstrate that the take number proposed for 
authorization (1,016) is small.
    For the potentially affected stocks of killer whale, it would be 
unreasonable to assume that all takes would accrue to any one stock. 
Although the Gulf of Alaska, Aleutian Islands, and Bering Sea (GOA/
BSAI) transient stock could occur in southeast Alaska, it is unlikely 
that any significant proportion of encountered whales would belong to 
this stock, which is generally considered to occur mainly from Prince 
William Sound through the Aleutian Islands and Bering Sea. Transient 
killer whales in Canadian waters are considered part of the West Coast 
transient stock, further minimizing the potential for encounter with 
the GOA/BSAI transient stock. We assume that only nominal, if any, take 
would actually accrue to this stock. Similarly, the offshore stock is 
encountered only rarely compared with resident and transient stocks. 
Seasonal sighting data collected in southeast Alaska waters between 
1991 and 2007 shows a ratio of offshore and resident killer whale 
sightings of 0.05 (Dahlheim et al., 2009), and it is unlikely that any 
amount of take accruing to this stock would exceed small numbers. We 
anticipate that most killer whales encountered would be transient or 
resident whales. For the remaining stocks, we assume that take would 
accrue to each stock in a manner roughly approximate to the stocks' 
relative abundances, i.e., 78 percent Alaska resident, 12 percent West 
Coast transient, and 10 percent northern resident. This would equate to 
approximately 226 takes from the Alaska resident stock (9.6 percent of 
the stock abundance); 35 takes from the West Coast transient stock (10 
percent of the stock abundance), and 29 takes from the northern 
resident stock (9.6 percent of the stock abundance). Based on the 
assumptions described in this paragraph, we preliminary find that the 
taking proposed for authorization is of no greater than small numbers 
for any stock of killer whale.
    If all takes proposed for authorization are allotted to each 
individual harbor seal stock, the estimated instances of take would be 
greater than one-third of the best available abundance estimate for the 
Sitka/Chatham Strait stock of harbor seal. However, similarly to the 
discussion provided above for killer whale, it would be unreasonable to 
assume that all takes would accrue to any one stock. Based on the 
location of the proposed survey relative to the potentially affected 
stocks' ranges, it is unlikely that a significant proportion of the 
estimated takes would occur to the Sitka/Chatham Strait stock (whose 
range just overlaps with the northern extent of the survey area) (Muto 
et al., 2020). A majority of takes are likely to accrue to the Dixon/
Cape Decision stock, which most directly overlaps with the proposed 
survey area. In the unlikely event that all takes occurred to the 
Dixon/Cape Decision stock, the amount of take would be of small 
numbers.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals will be taken relative to the population size 
of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    Marine mammals are legally hunted in Alaskan waters by coastal 
Alaska Natives. In the GOA, the only marine mammals under NMFS' 
jurisdiction that are currently hunted are Steller sea lions and harbor 
seals. These species are an important subsistence resource for Alaska 
Natives from southeast Alaska to the Aleutian Islands. There are 
numerous communities along the shores of the GOA that participate in 
subsistence hunting, including Juneau, Ketchikan, Sitka, and Yakutat in 
southeast Alaska (Wolfe et al., 2013). According to Muto et al. (2019), 
the annual subsistence take of Steller sea lions from the eastern stock 
was 11, and 415 northern fur seals are taken annually. In addition, 340 
harbor seals are taken annually (Muto et al. 2019). The seal harvest 
throughout Southeast Alaska is generally highest during spring and 
fall, but can occur any time of the year (Wolfe et al., 2013).
    Given the temporary nature of the proposed activities and the fact 
that most operations would occur further from shore, the proposed 
activity would not be expected to have any impact on the availability 
of the species or stocks for subsistence users. L-DEO is conducting 
outreach to local stakeholders, including subsistence communities, to 
notify subsistence hunters of the planned survey, to identify the 
measures that would be taken to minimize any effects on the 
availability of marine mammals for subsistence uses, and to provide an 
opportunity for comment on these measures. During operations, radio 
communications and Notice to Mariners would keep interested parties 
apprised of vessel activities. NMFS is unaware of any other subsistence 
uses of the affected marine mammal stocks or species that could be 
implicated by this action. Therefore, NMFS has preliminarily determined 
that the total taking of affected species or stocks would not have an 
unmitigable adverse impact on the availability of such species or 
stocks for taking for subsistence purposes. NMFS requests comments or 
any information that may help to inform this determination.

Endangered Species Act (ESA)

    Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.) 
requires that each Federal agency insure that any action it authorizes, 
funds, or carries out is not likely to jeopardize the continued 
existence of any endangered or threatened species or result in the 
destruction or adverse modification of designated critical habitat. To 
ensure ESA compliance for the issuance of IHAs, NMFS consults 
internally whenever we propose to authorize take for endangered or 
threatened species.
    NMFS is proposing to authorize take of blue whales, fin whales, sei 
whales, sperm whales, Mexico DPS humpback whales, western DPS Steller 
sea lions, and WNP gray whales, which are listed under the ESA. The 
NMFS OPR Permits and Conservation Division has requested initiation of 
Section 7 consultation with the NMFS OPR ESA Interagency Cooperation 
Division for the issuance of this IHA. NMFS will conclude the ESA 
consultation prior to reaching a determination regarding the proposed 
issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to L-DEO for conducting a marine geophysical survey in the 
northeast Pacific beginning in July 2021, provided the previously 
mentioned mitigation, monitoring, and reporting requirements are 
incorporated. A draft of the proposed IHA can be found at 
www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of Proposed IHA for the proposed 
geophysical survey. We also request at this time comment on the 
potential Renewal of this proposed IHA as described in the paragraph 
below. Please include with your comments any supporting data or 
literature citations to help inform decisions on the request for this 
IHA or a subsequent Renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time, one-year 
Renewal IHA following notice to the public providing

[[Page 30034]]

an additional 15 days for public comments when (1) up to another year 
of identical, or nearly identical, activities as described in the 
Description of Proposed Activity section of this notice is planned or 
(2) the activities as described in the Description of Proposed Activity 
section of this notice would not be completed by the time the IHA 
expires and a Renewal would allow for completion of the activities 
beyond that described in the Dates and Duration section of this notice, 
provided all of the following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed Renewal IHA effective date (recognizing that the 
Renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA);
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested Renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take); 
and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
     Upon review of the request for Renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: May 28, 2021.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2021-11718 Filed 6-3-21; 8:45 am]
BILLING CODE 3510-22-P