[Federal Register Volume 84, Number 68 (Tuesday, April 9, 2019)]
[Notices]
[Pages 14200-14240]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-06886]



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Vol. 84

Tuesday,

No. 68

April 9, 2019

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to a Marine Geophysical Survey in the Gulf of 
Alaska; Notice

  Federal Register / Vol. 84 , No. 68 / Tuesday, April 9, 2019 / 
Notices  

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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XG736


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey in the 
Gulf of Alaska

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 in the Gulf of 
Alaska. 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-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 May 9, 
2019.

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. Attachments 
to electronic comments will be accepted in Microsoft Word or Excel or 
Adobe PDF file formats only. All comments received are a part of the 
public record and will generally be posted online at https://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: Gray Redding, 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: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. 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 such 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 such 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 
incidental harassment authorization) with respect to potential impacts 
on the human environment.
    Accordingly, NMFS plans to adopt the National Science Foundation's 
(NSF) EA, provided our independent evaluation of the document finds 
that it includes adequate information analyzing the effects on the 
human environment of issuing the IHA. NMFS is a cooperating agency on 
NSF's EA. NSF's EA will be made available for public comment at https://www.nsf.gov/geo/oce/envcomp/ on approximately April 1, 2019. 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 November 20, 2018, NMFS received a request from L-DEO for an IHA 
to take marine mammals incidental to conducting seismic geophysical 
surveys in the Gulf of Alaska along the Alaska Peninsula subduction 
zone. On December 19, 2018, NMFS received a revised copy of the 
application, and that application was deemed adequate and complete on 
February 11, 2019. L-DEO's request is for take of a small number of 21 
marine mammal species by Level B harassment and Level A harassment. 
Underwater sound associated with airgun use may result in the 
behavioral harassment or auditory injury of marine mammals in the 
ensonified areas. Neither L-DEO nor NMFS expects serious injury or 
mortality to result from this activity and, therefore, an IHA is 
appropriate.
    NMFS previously issued an IHA to L-DEO for similar work (76 FR 
38621; July 1, 2011). L-DEO complied with all the requirements (e.g., 
mitigation, monitoring, and reporting) of the previous IHA and 
information regarding their monitoring results may be found in the 
``Description of Marine Mammals in the Area of Specified Activities.''

Description of Proposed Activity

Overview

    The specified activity consists of a high energy geophysical 
seismic survey conducted in a portion of the Gulf of

[[Page 14201]]

Alaska. Researchers from Lamont-Doherty Earth Observatory (L-DEO), 
Cornell University, Colgate University, University of Washington, 
University of California Santa Cruz, University of Colorado Boulder, 
University of New Mexico, Washington University in St. Louis, and the 
United States Geological Survey (USGS), with funding from NSF, propose 
to conduct the seismic survey from the Research Vessel (R/V) Marcus G. 
Langseth (Langseth) in the Gulf of Alaska during 2019. The NSF-owned 
Langseth is operated by Columbia University's L-DEO under an existing 
Cooperative Agreement. The proposed seismic survey would likely occur 
off the Alaska Peninsula and the eastern Aleutian islands during late 
spring 2019 and would use a 36-airgun towed array with a total 
discharge volume of ~6600 in\3\. The survey would take place within the 
U.S. Exclusive Economic Zone (EEZ), in water ~15 to ~6,184 m deep.
    The main goal of L-DEO's proposed seismic program is to conduct a 
2D survey along the Alaska Peninsula subduction zone using airguns. The 
addition of active sources (airguns) to the existing seismic monitoring 
equipment in place would directly contribute to the overall project 
goals of imaging the architecture for the subduction zone and 
understanding the structures controlling how and where the planet's 
largest earthquakes occur.

Dates and Duration

    The survey is expected to consist of up to 18 days of seismic 
operations and ~1 day of transit. The Langseth would leave from and 
return to port in Kodiak, likely during late spring (end of May/early 
June) 2019. Tentative sail dates are 1-19 June 2019.
    Timing of the proposed survey will take advantage of the Alaska 
Amphibious Community Seismic Experiment (AACSE), which has deployed 75 
ocean bottom seismometers (OBSs) offshore of the Alaska Peninsula. The 
survey needs to be conducted while the AACSE OBSs are on the sea floor 
(before 6 August 2019). The most value-added time window is mid-May 
through mid-June, when an on-shore seismic array, consisting of 400-450 
onshore seismometers will also be deployed on Kodiak Island and which 
could record an unprecedented ship-to-shore dataset.

Specific Geographic Region

    The proposed survey would occur within the area of ~52-58[deg] N, 
~150-162[deg] W, within the EEZ of Alaska in water depths ranging from 
~15 to ~6184 m. Representative survey tracklines are shown in Figure 1. 
As described further in this document, however, deviation in actual 
track lines, including 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. Thus, within the constraints of any federal authorizations 
issued for the activity, tracklines may shift from those shown in the 
application and could occur anywhere within the coordinates noted above 
and illustrated by the box in the inset map on Figure 1 of the IHA 
application.
[GRAPHIC] [TIFF OMITTED] TN09AP19.000


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Detailed Description of Specific Activity

    The procedures to be used for the proposed surveys 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 Langseth, which is owned by NSF and operated on its behalf 
by Columbia University's L-DEO. The Langseth would deploy an array of 
36 airguns as an energy source with a total volume of ~6,600 in\3\. The 
receiving system would consist of previously deployed OBSs and onshore 
seismometers (See Figure 2 in IHA Application), as well as a single 
hydrophone streamer 5 kilometers (km) in length; no hydrophone streamer 
would be towed during the survey. As the airgun arrays are towed along 
the survey lines, the seismometers would receive and store the 
returning acoustic signals internally for later analysis and the 
hydrophone streamer would transfer the data to the on-board processing 
system.
    For this proposed survey, a total of ~4400 km of transect lines 
would be surveyed in the Gulf of Alaska (GOA). There could be 
additional seismic operations associated with turns, airgun testing, 
and repeat coverage of any areas where initial data quality is sub-
standard. To account for unanticipated delays, 25 percent has been 
added in the form of operational days, which is equivalent to adding 25 
percent to the proposed line km to be surveyed. During the survey, 
approximately 13 percent of the line km would take place in shallow 
water (<100 meter (m)), 27 percent would occur in intermediate water 
depths (100-1000 m), and the rest (60 percent) would occur in deep 
water (>1000 m).
    In addition to the operations of the airgun array, the ocean floor 
would be mapped with a Kongsberg EM 122 multibeam echosounder (MBES) 
and a Knudsen Chirp 3260 sub-bottom profiler (SBP). A Teledyne RDI 75 
kilohertz (kHz) Ocean Surveyor Acoustic Doppler Current Profiler (ADCP) 
would be used to measure water current velocities. These sources would 
be operated from the Langseth continuously during the seismic survey, 
but not during transit to and from the survey areas. All planned 
geophysical data acquisition activities would be conducted by L-DEO 
with on-board assistance by the scientists who have proposed the 
studies. The vessel would be self-contained, and the crew would live 
aboard the vessel.
    During the survey, the Langseth would tow the full array, 
consisting of four strings with 36 airguns (plus 4 spares) and a total 
volume of ~6,600 in\3\. The 4-string array would be towed at a depth of 
12 m, and the shot intervals would be 399.3 m for the entire survey.
    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's Stock Assessment Reports (SAR; https://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's 
website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all species with expected potential for occurrence in 
the Gulf of Alaska and summarizes information related to the population 
or stock, including regulatory status under the MMPA and ESA and 
potential biological removal (PBR), where known. For taxonomy, we 
follow Committee on Taxonomy (2017). 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 as gross indicators of the status of the species and 
other threats.
    Sixteen species of cetaceans and five species of pinnipeds could 
occur in the proposed Gulf of Alaska survey area. Cetacean species 
include seven species of mysticetes (baleen whales) and nine species of 
odontocetes (dolphins and small and large toothed whales).
    Ferguson et al. (2015) described Biological Important Areas (BIAs) 
for cetaceans in the Gulf of Alaska. BIAs were delineated for four 
baleen whale species and one toothed whale species including fin, gray, 
North Pacific right, and humpback whales, and belugas in U.S. waters of 
the Gulf of Alaska. BIAs are described in the following sections for 
each marine mammal species, except for beluga whale BIAs, as these do 
not co-occur within L-DEO's proposed survey area and the species is not 
expected to be present there. BIAs are delineated for feeding, 
migratory corridors, and small and resident populations. Supporting 
evidence for these BIAs came from aerial-, land-, and vessel-based 
surveys; satellite tagging data; passive acoustic monitoring; 
traditional ecological knowledge; photo- and genetic-identification 
data; whaling data, including catch and sighting locations and stomach 
contents; prey studies; and observations from fishermen.
    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's 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, stock abundance estimates are 
not available, and survey abundance estimates are used. This survey 
area may or may not align completely with a stock's geographic range as 
defined in the SARs. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS's U.S. Alaska and U.S. Pacific SARs (e.g., Muto et al. 2018, 
Carretta et al. 2018). All values presented in Table 1 are the most 
recent available at the time of publication and are available in the 
2017 SARs (Muto et al. 2018, Carretta et al. 2018) and draft 2018 SARs 
(available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports).

[[Page 14203]]



                               Table 1--Marine Mammals That Could Occur in the Project Area During the Specified Activity
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                                                                                    ESA/MMPA     Stock abundance (CV,
                                                                                    status;        Nmin, most recent                         Annual M/SI
            Common name                Scientific name            Stock         strategic (Y/N)    abundance survey)            PBR              \3\
                                                                                      \1\                 \2\
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
    Gray whale....................  Eschrichtius          Eastern North         -, -, N          26,960 (0.05,         801.................          138
                                     robustus.             Pacific.                               25,849, 2016).
                                                          Western North         E, D, Y          175 (0.05, 167,       0.07................          UNK
                                                           Pacific.                               2016).
Family Balaenidae:
    North Pacific right whale.....  Eubalaena japonica..  Eastern North         E, D, Y          31 (0.226, 26, 2015)  0.05 b..............            0
                                                           Pacific.
Family Balaenopteridae (rorquals):
    Blue whale....................  Balaenoptera          Eastern North         E, D, Y          1,647 (0.07, 1,551,   2.3.................        >=0.2
                                     musculus.             Pacific.                               2011).
                                                          Central North         E, D, Y          133 (1.09, 63, 2010)  0.1.................            0
                                                           Pacific.
    Fin whale * \4\...............  Balaenoptera          Northeast Pacific...  E, D, Y          3,168 \4\...........  5.1.................          0.6
                                     physalus.
    Sei whale.....................  Balaenoptera          Eastern North         E, D, Y          519 (0.4, 374, 2014)  0.75................            0
                                     borealis.             Pacific.
    Minke whale * \5\.............  Balaenoptera          Alaska..............  -, -, N          1,233 \5\...........  UND.................            0
                                     acutorostrata.
    Humpback whale................  Megaptera             Central North         -, -, Y          10,103 (0.3, 7,890,   83..................           25
                                     novaeangliae.         Pacific.                               2006).
                                                          Western North         E, D, Y          1,107 (0.3, 865,      3...................          3.2
                                                           Pacific.                               2006).
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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          N/A (see SAR, N/A,    see SAR.............          4.4
                                     macrocephalus.                                               2015).
Family Ziphiidae (beaked whales):
    Cuvier's beaked whale.........  Ziphius cavirostris.  Alaska..............  -, -, N          N/A (see SAR, N/A,    UND.................            0
                                                                                                  see SAR).
    Baird's beaked whale..........  Berardius bairdii...  Alaska..............  -, -, N          N/A (see SAR, N/A,    UND.................            0
                                                                                                  see SAR).
    Stejneger's beaked whale......  Mesoplodon            Alaska..............  -, -, N          N/A (see SAR, N/A,    UND.................            0
                                     stejnegeri.                                                  see SAR).
Family Delphinidae:
    Killer whale..................  Orcinus orca........  Eastern North         -, -, N          2,347 c (N/A, 2347,   24..................            1
                                                           Pacific Alaska                         2012).
                                                           Resident.
                                                          Gulf of Alaska,       -, -, N          587 c (N/A, 587,      5.87................            1
                                                           Aleutian Islands,                      2012).
                                                           and Bering Sea
                                                           Transient.
                                                          AT1 Transient.......  -, D, Y          7 c (N/A, 7, 2017)..  0.01................            0
                                                          Offshore............  -, -, N          240 (0.49, 162,       1.6.................            0
                                                                                                  2014).
    Risso's dolphin...............  Grampus griseus.....  CA/WA/OR............  -, -, N          6,336 (0.32, 4,817,   46..................        >=3.7
                                                                                                  2014).
    Pacific white[dash]sided        Lagenorhynchus        North Pacific.......  -, -, N          26,880 (N/A, N/A,     UND.................            0
     dolphin.                        obliquidens.                                                 1990).
Family Phocoenidae (porpoises):
    Harbor porpoise...............  Phocoena phocoena...  GOA.................  -, -, Y          31,046 (0.214, N/A,   UND.................           72
                                                                                                  1998).
                                                          Southeast Alaska....  -, -, Y          see SAR (see SAR,     8.9.................           34
                                                                                                  see SAR, 2012).
    Dall's porpoise...............  Phocoenoides dalli..  Alaska..............  -, -, N          83,400 (0.097, N/A,   UND.................           38
                                                                                                  1991).
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                                                         Order Carnivora--Superfamily Pinnipedia
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Family Otariidae (eared seals and
 sea lions):
    Steller sea lion..............  Eumetopias jubatus..  Eastern U.S.........  T, D, Y          41,638 a (see SAR,    2,498...............          108
                                                                                                  41,638, 2015).
                                                          Western U.S.........  E, D, Y          54,267 a (see SAR,    326.................          252
                                                                                                  54,267, 2017).
    California sea lion...........  Zalophus              U.S.................  -, -, N          296,750 (N/A,         9,200...............          389
                                     californianus.                                               153,337, 2011).
    Northern fur seal.............  Callorhinus ursinus.  Eastern Pacific.....  -, D, Y          620,660 (0.2,         11,295..............          457
                                                                                                  525,333, 2016).
Family Phocidae (earless seals):
    Northern elephant seal........  Mirounga              California Breeding.  -, -, N          179,000 (N/A,         4,882...............          8.8
                                     angustirostris.                                              81,368, 2010).
    Harbor seal...................  Phoca vitulina......  South Kodiak........  -, -, N          19,199 (see SAR,      314.................          128
                                                                                                  17,479, 2011).
                                                          Cook Inlet/Shelikof   -, -, N          27,386 (see SAR,      770.................          234
                                                           Strait.                                25,651, 2011).
                                                          Prince William        -, -, N          29,889 (see SAR,      838.................          279
                                                           Sound?.                                27,936, 2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Stocks marked with an asterisk are addressed in further detail in text below.
\1\ 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 online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable (N/A).
\3\ 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, ship strike).
\4\ Uncorrected estimate from Rone et al. (2017) based on a series of line-transect surveys off of Kodiak Island. The maximum estimate from the three
  surveys was selected. Based on the limited footprint of the surveys that lead to this estimate, the true abundance of the stock is expected to be much
  higher.

[[Page 14204]]

 
\5\ Uncorrected estimate from Zerbini et al., (2006) based on a partial line-transect survey of the Gulf of Alaska.
Note--Italicized species or stocks are not expected to be taken or proposed for authorization.

    All species that could potentially occur in the proposed survey 
areas are included in Table 1. With the exception of AT1 transient 
killer whales, these species or stocks temporally and spatially co-
occur with the activity to the degree that take is reasonably likely to 
occur. However, the spatial occurrence of the AT1 transient is such 
that take is not expected to occur, and they are not discussed further 
beyond the explanation provided here.
    AT1 transient killer whales are a small, genetically distinct 
population of transient ecotype killer whales found in the Gulf of 
Alaska (Matkin et al. 1999). The population has declined from a size of 
22 whales in 1984, to just 7 today, and it is believed this decline was 
associated with the Exxon Valdez Oil Spill in 1989 (Matkin et al. 
2008). AT1 transients have only ever been seen in Prince William Sound 
and in the Kenai Fjords region (Muto et al. 2018; Matkin et al. 2008). 
Therefore, while the stock is present in the Gulf of Alaska, and 
deserved consideration, the limited range of the stock and the fact 
that this range does not overlap with L-DEO's proposed survey means 
take is not likely to occur for the AT1 stock of transient killer 
whales.
    No comprehensive abundance estimate is available for the Alaska 
stock of minke whales. The best available estimate for the area comes 
from line-transect surveys 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 (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. This estimate 
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, there are provisional 
estimates representing relevant portions of the range. Zerbini et al. 
(2006) produced an estimate of 1,652 (95 percent CI: 1,142-2,389) fin 
whales for the area described above. Additionally, a series of line-
transect surveys off of Kodiak Island and the in the northern Gulf of 
Alaska conducted in 2009, 2013, and 2015, generated a maximum estimate 
of 3,168 (CV = 0.26) (also not been corrected for animals missed on the 
trackline) (Rone et al. 2017).
    Kato and Miyashita (1998) reported 102,112 sperm whales (CV = 
0.155) in the western North Pacific, however, with the caveat that 
their estimate is likely positively biased. From surveys in the Gulf of 
Alaska in 2009 and 2015, Rone et al. (2017) estimated 129 (CV = 0.44) 
and 345 sperm whales (CV = 0.43) in each year, respectively. The 
overall number of sperm whales occurring in Alaska waters is unknown 
(Muto et al. 2018).
    For the three species of beaked whale expected to occur in the area 
(Baird's, Cuvier's, and Stejneger's), there are no reliable estimates 
of abundance.
    We have reviewed L-DEO's species descriptions, including life 
history information, distribution, regional distribution, diving 
behavior, and acoustics and hearing, for accuracy and completeness. 
Below, for the 21 species that are likely to be taken by the activities 
described, we offer a brief introduction to the species and relevant 
stock as well as available information regarding population trends and 
threats, and describe any information regarding local occurrence.
    In addition, the northern sea otter (Enhydra lutris) and Pacific 
walrus (Odobenus rosmarus divergens) may be found in the Gulf of 
Alaska. However, northern sea otter and Pacific walrus are managed by 
the U.S. Fish and Wildlife Service and are not considered further in 
this document.

Mysticetes

North Pacific Right Whale (Eubalaena japonica)
    North Pacific right whales summer in the northern North Pacific, 
primarily in the Okhotsk Sea (Brownell et al. 2001) and in the Bering 
Sea (Shelden et al. 2005; Wade et al. 2006). This species is divided 
into western and eastern North Pacific stocks. The eastern North 
Pacific stock that occurs in U.S. waters numbers only ~31 individuals 
(Wade et al. 2011b), and critical habitat has been designated in the 
eastern Bering Sea and in the GOA, south of Kodiak Island (NMFS 2017b). 
Wintering and breeding areas are unknown, but have been suggested to 
include the Hawaiian Islands, Ryukyu Islands, and Sea of Japan (Allen 
1942; Banfield 1974; Gilmore 1978; Reeves et al. 1978; Herman et al. 
1980; Omura 1986).
    Since the 1960s, North Pacific right whale sightings have been 
relatively rare (e.g., Clapham et al. 2004; Shelden et al. 2005). In 
the eastern North Pacific, south of 50 [deg]N, only 29 reliable 
sightings were recorded from 1900 to 1994 (Scarff 1986, 1991; Carretta 
et al. 1994). Starting in 1996, right whales have been sighted 
regularly in the southeast Bering Sea, including calves in some years 
(Goddard and Rugh 1998; LeDuc et al. 2001; Moore et al. 2000, 2002b; 
Wade et al. 2006; Zerbini et al. 2009); they have also been detected 
acoustically when sonobuoys were deployed (McDonald and Moore 2002; 
Munger et al. 2003, 2005, 2008; Berchok et al. 2009). Right whales are 
known to occur in the southeast Bering Sea from May to December (e.g., 
Tynan et al. 2001; Hildebrand and Munger 2005; Munger et al. 2005, 
2008). Call frequencies tended to be higher in July-October than from 
May-June or November-December (Munger et al. 2008). Right whales seem 
to pass through the middle-shelf areas, without remaining there longer 
than a few days (Munger et al. 2008).
    Shelden et al. (2005) reported that the slope and abyssal plain in 
the western GOA were important areas for right whales until the late 
1960s, but sightings and acoustic detections in this region in recent 
decades are rare. In March 1979, a group of four right whales was seen 
in Yakutat Bay (Waite et al. 2003), but there were no further reports 
of right whale sightings in the GOA until July 1998, when a single 
whale was seen southeast of Kodiak Island (Waite et al. 2003). Three 
sightings and one acoustic detection of right whales were made in 
Barnabas Trough south of Kodiak Island during NOAA surveys in 2004 to 
2006 in areas with high densities of zooplankton (Wade et al. 2011a). 
Those authors also report a fourth opportunistic sighting by a 
commercial fisher during that time in the same area. One right whale 
was sighted in the Aleutian Islands south of Unimak Pass in September 
2004 (Wade et al. 2011b). A BIA for feeding for North Pacific right 
whales was designated east of the Kodiak Archipelago, encompassing the 
GOA critical habitat and extending south of 56[deg] N and north of 
58[deg] N and beyond the shelf edge (Ferguson et al. 2015). Feeding 
primarily occurs in this BIA between June and September (Ferguson et 
al. 2015)
    Right whale acoustic detections were made south of the Alaska 
Peninsula and to the east of Kodiak Island in 2000 during August and 
September (see

[[Page 14205]]

Waite et al. 2003; Mellinger et al. 2004b), but no acoustic detections 
were made from April to August 2003 (Munger et al. 2008) or in April 
2009 (Rone et al. 2010). Three right whales were acoustically detected 
in the Barnabas Trench area during a towed-PAM survey of the U.S. Navy 
training area east of Kodiak in the summer of 2013 but none were 
observed visually (Rone et al. 2014). Right whales were not 
consistently detected acoustically from (2011-2015) with the fixed PAM 
monitoring in this region (Baumann-Pickering et al. 2012; Debich et al. 
2013; Rice et al. 2015), but there were detections on two days in June 
and August 2013 (Debich et al. 2014). No right whales were visually 
observed during the three years of surveys (2009, 2013, and 2015) in 
this military area east of Kodiak (Rone et al. 2017). There was one 
sighting of a single North Pacific right whale during the L-DEO seismic 
survey conducted in the summer of 2011 in the same area as the 
currently proposed survey (RPS 2011). There was another sighting of a 
lone North Pacific right whale during a marine mammal cruise, 
approximately 130 miles east of Kodiak Island in July 2012 (Matsuoka et 
al. 2013). Thus, it is possible that a right whale could be seen during 
the proposed survey.
Gray Whale (Eschrichtius robustus)
    Two separate populations of gray whales have been recognized in the 
North Pacific (LeDuc et al. 2002): The eastern North Pacific and 
western North Pacific (or Korean-Okhotsk) stocks. However, the 
distinction between these two populations has been recently debated 
owing to evidence that whales from the western feeding area also travel 
to breeding areas in the eastern North Pacific (Weller et al. 2012, 
2013; Mate et al. 2015). Thus, it is possible that whales from both the 
endangered Western North Pacific and the delisted Eastern North Pacific 
distinction population segments (DPSs) could occur in the proposed 
survey area in the eastern North Pacific.
    Gray whale populations were severely reduced by whaling, but the 
eastern North Pacific population is considered to have recovered. Punt 
and Wade (2012) estimated the eastern North Pacific population to be at 
85 percent of its carrying capacity in 2009. The eastern North Pacific 
gray whale breeds and winters in Baja, California, and migrates north 
to summer feeding grounds in the northern Bering Sea, Chukchi Sea, and 
western Beaufort Sea (Rice and Wolman 1971; Rice 1998; Jefferson et al. 
2015). Most of the eastern Pacific population makes a round-trip annual 
migration of more than 18,000 km. From late May to early October, the 
majority of the population concentrates in the northern and western 
Bering Sea and in the Chukchi Sea. However, some individuals spend the 
summer months scattered along the coasts of southeast Alaska, B.C., 
Washington, Oregon, and northern California (Rice and Wolman 1971; 
Nerini 1984; Darling et al. 1998; Dunham and Duffus 2001, 2002; 
Calambokidis et al. 2002). Gray whales are found primarily in shallow 
water; most follow the coast during migration, staying close to the 
shoreline except when crossing major bays, straits, and inlets (Braham 
1984).
    It is difficult to determine precisely when the southbound 
migration begins; whales near Barrow were moving predominantly south in 
August (Maher 1960; Braham 1984). Gray whales leave the Bering Sea 
through Unimak Pass from late October through January (Braham 1984). 
From October to January, the main part of the population moves down the 
west coast of North America. Rugh et al. (2001) analyzed data collected 
from two sites in California to estimate the timing of the gray whale 
southward migration. They estimated that the median date for the 
migration past various sites was 1 December in the central Bering Sea 
(a nominal starting point), 12 December at Unimak Pass, 18 December at 
Kodiak Island, and 5 January for Washington.
    By January and February, most of the whales are concentrated in the 
lagoons along the Pacific coast of the Baja Peninsula, Mexico. From 
late February to June, the population migrates northward to arctic and 
subarctic seas (Rice and Wolman 1971). The peak of northward migration 
in the GOA occurs in mid-April (Braham 1984). Most gray whales follow 
the coast during migration and stay within 2 km of the shoreline, 
except when crossing major bays, straits, and inlets from southeast 
Alaska to the eastern Bering Sea (Braham 1984). Gray whales use the 
nearshore areas of the Alaska Peninsula during the spring and fall 
migrations, and are often found within the bays and lagoons, primarily 
north of the peninsula, during the summer (Brueggeman et al. 1989 in 
Waite et al. 1999). However, gray whales are known to move further 
offshore between the entrance to Prince William Sound (PWS) and Kodiak 
Island and between Kodiak Island and the southern part of the Alaska 
Peninsula (Consiglieri et al. 1982). During May-October, primary 
occurrence extends seaward 28 km from the shoreline. This is the main 
migratory corridor for gray whales.
    In the summer, gray whales are seen in the southeast Bering Sea 
(Moore et al. 2002b) and in the GOA, including around Kodiak Island 
(e.g., Wade et al. 2003; Calambokidis et al. 2004; Calambokidis 2007; 
Moore et al. 2007). In fact, gray whales have been seen feeding off 
southeast Kodiak Island, in particular near Ugak Bay, year-round (Moore 
et al. 2007). Moore et al. (2007) noted monthly sighting rates that 
exceeded 100 sightings/h in January, June, September, and November, and 
>20 sightings/h in most other months. One feeding aggregation in July 
consisted of 350-400 animals, clustered in groups of 10-20 animals, 
from the mouth of Ugak Bay to 100 km ESE of Ugak Island (Moore et al. 
2007). Wade et al. (2003) reported a group size of 5.6 in the western 
GOA. A biologically important area (BIA) for feeding for gray whales 
has been identified in the waters east of the Kodiak Archipelago, with 
the greatest densities of gray whales occurring from June through 
August (Ferguson et al. 2015). Additionally, a gray whale migratory 
corridor BIA has been established extending from Unimak Pass in the 
western GOA to the Canadian border in the eastern GOA (Ferguson et al. 
2015), including much of the landward side of the survey area. Gray 
whales occur in this area in high densities during November through 
January (southbound) and March through May (northbound).
    Rone et al. (2017) sighted gray whales off Ugak Island, Kodiak, in 
all three years (2009, 2013, and 2015) of surveys in the military 
training area east of Kodiak. Gray whales were detected acoustically 
throughout the summer and fall at fixed hydrophones on the shelf off 
Kenai Peninsula and near Kodiak Island in this military training area 
in a 2014-2015 study (Rice et al. 2015), but they were not detected at 
deeper slope or seamount sites and they were detected only once in 
prior years of study from 2011 to 2013 (Baumann-Pickering et al. 2012; 
Debich et al. 2013). Gray whales were neither observed visually nor 
detected acoustically during the L-DEO seismic survey conducted in the 
summer of 2011 in the same area as the currently proposed survey (RPS 
2011). Gray whales could be encountered during the proposed seismic 
survey in the GOA.
Humpback Whale (Megaptera novaeangliae)
    The humpback whale is found throughout all oceans of the World 
(Clapham 2009), with recent genetic evidence suggesting three separate 
subspecies: North Pacific, North Atlantic, and Southern Hemisphere

[[Page 14206]]

(Jackson et al. 2014). Nonetheless, genetic analyses suggest some gene 
flow (either past or present) between the North and South Pacific 
(e.g., Jackson et al. 2014; Bettridge et al. 2015). Although considered 
to be mainly a coastal species, the humpback whale often traverses deep 
pelagic areas while migrating (e.g., Mate et al. 1999; Garrigue et al. 
2015).
    North Pacific humpback whales migrate between summer feeding 
grounds along the Pacific Rim and the Bering and Okhotsk seas and 
winter calving and breeding areas in subtropical and tropical waters 
(Pike and MacAskie 1969; Rice 1978; Winn and Reichley 1985; 
Calambokidis et al. 2000, 2001, 2008). In the North Pacific, humpbacks 
winter in four different breeding areas: (1) Along the coast of Mexico; 
(2) along the coast of Central America; (3) around the Main Hawaiian 
Islands; and (4) in the western Pacific, particularly around the 
Ogasawara and Ryukyu islands in southern Japan and the northern 
Philippines (Calambokidis et al. 2008; Fleming and Jackson 2011; 
Bettridge et al. 2015). These breeding areas are recognized as the 
Mexico, Central America, Hawaii, and Western Pacific DPSs (NMFS 2016b). 
Hawaii is the primary wintering area for whales from summer feeding 
areas in the Gulf of Alaska (Calambokidis et al. 2008). Individuals 
from the Hawaii, Western Pacific, and Mexico DPSs could occur in the 
proposed survey area to feed. The Hawaii DPS is not listed and the 
Mexico DPS is listed as threatened under the ESA. Additionally, the 
Western North Pacific stock, analogous to the western Pacific DPS, is 
listed as endangered under the ESA.
    There is potential for mixing of the western and eastern North 
Pacific humpback populations on their summer feeding grounds, and 
several sources suggest that this occurs to a limited extent (Muto et 
al. 2018). NMFS is currently reviewing the global humpback whale stock 
structure in light of the recent revision to their ESA listing and 
identification of 14 DPSs (81 FR 62259; 8 September 2016). Currently, 
two stocks of humpback whales are recognized as occurring in Alaskan 
waters. The Central North Pacific Stock occurs from southeast Alaska to 
the Alaska Peninsula and the Western North Pacific Stock occurs from 
the Aleutians to the Bering Sea and Russia. These two stocks overlap on 
feeding grounds in the eastern Bering Sea and the western Gulf of 
Alaska (Muto et al. 2018), encompassing the entire proposed survey 
area. BIAs for humpback whale feeding have been designated surrounding 
Kodiak Island and the Shumagin Islands (Ferguson et al. 2015). The 
highest densities of humpback whales occur during July through 
September around Kodiak Island and during July through August in the 
Shumagin Islands.
    Humpback whales are commonly sighted within the proposed survey 
area. Waite (2003) reported that 117 humpbacks were seen in 41 groups 
during their surveys in the western GOA in 2003, with aggregations seen 
off northeast Kodiak Island. During summer surveys from the Kenai 
Fjords to the central Aleutian Islands in 2001-2003, humpbacks were 
most abundant near Kodiak Island, the Shumagin Islands, and north of 
Unimak Pass (Zerbini et al. 2006). Sightings of humpbacks around the 
Kodiak Islands were made most frequently in the fall, and aggregations 
were seen off Shuyak and Sitkalidak islands (Wynne and Witteveen 2005), 
as well as in Marmot and Chiniak bays (Baraff et al. 2005). Waite et 
al. (1999) noted another aggregation area north of Unalaska Island. 
Offshore sightings of humpbacks have also been made south of the Alaska 
Peninsula, including ~280 km south of the Shumagin Islands (e.g., 
Forney and Brownell 1996; Waite et al. 1999). Humpback whales were 
sighted a total of 220 times (637 animals) during the three years of 
surveys (2009, 2013, and 2015) in and near the U.S. Navy training area 
east of Kodiak (Rone et al. 2017). Humpback whales were also frequently 
detected acoustically during all years (2011-2015) of fixed-PAM studies 
in this area, with peak detections during late fall through early 
winter and detections at all shelf, slope, and seamount sites (Baumann-
Pickering et al. 2012; Debich et al. 2013; Rice et al. 2015). Humpback 
whales were the most frequently sighted cetacean during the L-DEO 
seismic survey conducted in the summer of 2011 in the same area as the 
currently proposed survey, comprising 50 percent of all cetacean 
sightings (RPS 2011). There were 92 sightings of this species, 
representing 288 animals during the 37 days of monitoring. The average 
group size was three and the maximum group size was 37. This species is 
likely to be common in the proposed survey area.
    Calambokidis et al. (2008) reported an abundance estimate of 3,000-
5,000 for the GOA. Rone et al. (2017) calculated an abundance estimate 
of 2,215 (uncorrected for missed animals) from a June-July 2013 survey 
in the U.S. Navy training area east of Kodiak Island, with the bulk of 
this estimate (2,927) found in the inshore stratum. NMFS provides best 
estimates of 1,107 for the Western North Pacific Stock and 10,103 for 
the Central North Pacific Stock (Muto et al. 2018). Within the Central 
North Pacific stock, the Hawaii DPS is estimated to contain 11,398 
animals where the Mexico DPS is estimated to contain 3,264 animals (81 
FR 62259; effective October 11, 2016).
Minke Whale (Balaenoptera acutorostrata)
    The minke whale has a cosmopolitan distribution ranging from the 
tropics and subtropics to the ice edge in both hemispheres (Jefferson 
et al. 2015). In the Northern Hemisphere, minke whales are usually seen 
in coastal areas, but can also be seen in pelagic waters during 
northward migrations in spring and summer, and southward migration in 
autumn (Stewart and Leatherwood 1985). In the North Pacific, the summer 
range extends to the Chukchi Sea; in the winter, minke whales move 
further south to within 2[deg] of the Equator (Perrin and Brownell 
2009). The International Whaling Commission (IWC) recognizes three 
stocks in the North Pacific: The Sea of Japan/East China Sea, the rest 
of the western Pacific west of 180[deg]N, and the remainder of the 
Pacific (Donovan 1991). NMFS recognizes a single stock in Alaskan 
waters and a second California/Oregon/Washington Stock (Muto et al. 
2016).
    The minke whale tends to be solitary or in groups of 2-3 but can 
occur in much larger aggregations around prey resources (Jefferson et 
al. 2008). Predominantly solitary animals were seen during surveys in 
Alaska (Wade et al. 2003; Waite 2003; Zerbini et al. 2006). The small 
size, inconspicuous blows, and brief surfacing times of minke whales 
mean that they are easily overlooked in heavy sea states, although they 
are known to approach vessels in some circumstances (Stewart and 
Leatherwood 1985). Little is known about the diving behavior of minke 
whales, but they are not known to make prolonged deep dives 
(Leatherwood and Reeves 1983).
    Minke whales are relatively common in the Bering and Chukchi seas 
and in the inshore waters of the GOA (Mizroch 1992), but they are not 
considered abundant in any other part of the eastern Pacific 
(Brueggeman et al. 1990). Waite (2003) sighted four minke whales in 
three groups during surveys in the western GOA in 2003, south of the 
Kenai Peninsula and south of PWS. Moore et al. (2002b) reported a minke 
whale sighting south of the Sanak Islands. Baraff et al. (2005) 
reported a single sighting near Kodiak Island in July 2002. During 
surveys in the western GOA and eastern Aleutians, minke whales occurred 
primarily in the Aleutians; a few sightings were made

[[Page 14207]]

south of the Alaska Peninsula and near Kodiak Island (Zerbini et al. 
2006). Rone et al. (2017) reported two sightings totaling three minke 
whales in 2009, three sightings totaling six minke whales in 2013, and 
no sightings of minke whales in 2015 in the U.S. Navy training area 
east of Kodiak. Minke whales were not detected acoustically during any 
year (2011-2015) of the fixed-PAM studies in the Department of the Navy 
(DoN) area east of Kodiak (Baumann-Pickering et al. 2012; Debich et al. 
2013; Rice et al. 2015). There was one sighting of a single minke whale 
during the L-DEO seismic survey conducted in the summer of 2011 in the 
same area as the currently proposed survey (RPS 2011).
Sei Whale (Balaenoptera borealis)
    The sei whale occurs in all ocean basins (Horwood 2009) but appears 
to prefer mid-latitude temperate waters (Jefferson et al. 2015). It 
undertakes seasonal migrations to feed in subpolar latitudes during 
summer and returns to lower latitudes during winter to calve (Horwood 
2009). The sei whale is pelagic and generally not found in coastal 
waters (Harwood and Wilson 2001). It occurs in deeper waters 
characteristic of the continental shelf edge region (Hain et al. 1985) 
and in other regions of steep bathymetric relief such as seamounts and 
canyons (Kenney and Winn 1987; Gregr and Trites 2001). On feeding 
grounds, sei whales associate with oceanic frontal systems (Horwood 
1987) such as the cold eastern currents in the North Pacific (Perry et 
al. 1999). Sei whales are frequently seen in groups of 2-5 (Jefferson 
et al. 2008), although larger groups sometimes form on feeding grounds 
(Gambell 1985a).
    In the U.S. Pacific, an Eastern North Pacific and a Hawaii stock 
are recognized (Carretta et al. 2017). During summer in the North 
Pacific, the sei whale can be found from the Bering Sea to the northern 
GOA and south to California, and in the western Pacific from Japan to 
Korea. Its winter distribution is concentrated at about 20[deg] N, and 
sightings have been made between southern Baja California and the Islas 
Revilla Gigedo (Rice 1998). No breeding grounds have been identified 
for sei whales; however, calving is thought to occur from September to 
March.
    Moore et al. (2002b) made four sightings of six sei whales during 
summer surveys in the eastern Bering Sea, and one sighting south of the 
Alaska Peninsula between Kodiak and the Shumagin Islands. No sei whales 
were seen during surveys of the GOA by Wade et al. (2003), Waite 
(2003), or Zerbini et al. (2006). Rone et al. (2017) reported no sei 
whale sightings in 2009 or 2013 and a single sei whale sighting of one 
animal in 2015 in the U.S. Navy training area east of Kodiak. There was 
one sighting of two sei whales during the L-DEO seismic survey 
conducted in the summer of 2011 in the same area as the currently 
proposed survey (RPS 2011). During a 2012 survey in summer and early 
fall, Matsuoka et al. (2013) reported 87 sei whale sightings of 1,647 
individuals, however the majority of these sightings were far south of 
the action area. Sei whale sightings are likely to be uncommon in the 
proposed survey area.
Fin Whale (Balaenoptera physalus)
    The fin whale is widely distributed in all the World's oceans 
(Gambell 1985b), although it is most abundant in temperate and cold 
waters (Aguilar 2009). Nonetheless, its overall range and distribution 
are not well known (Jefferson et al. 2015). A recent review of fin 
whale distribution in the North Pacific noted the lack of sightings 
across the pelagic waters between eastern and western winter areas 
(Mizroch et al. 2009). The fin whale most commonly occurs offshore but 
can also be found in coastal areas (Aguilar 2009). Most populations 
migrate seasonally between temperate waters where mating and calving 
occur in winter, and polar waters where feeding occurs in summer 
(Aguilar 2009). However, recent evidence suggests that some animals may 
remain at high latitudes in winter or low latitudes in summer (Edwards 
et al. 2015).
    The fin whale is known to use the shelf edge as a migration route 
(Evans 1987). Sergeant (1977) suggested that fin whales tend to follow 
steep slope contours, either because they detect them readily, or 
because the contours are areas of high biological productivity. 
However, fin whale movements have been reported to be complex 
(Jefferson et al. 2015). Stafford et al. (2009) noted that sea-surface 
temperature is a good predictor variable for fin whale call detections 
in the North Pacific.
    North Pacific fin whales summer from the Chukchi Sea to California 
and winter from California southwards (Gambell 1985b). In the United 
States, three stocks are recognized in the North Pacific: California/
Oregon/Washington, Hawaii, and Alaska (Northeast Pacific) (Carretta et 
al. 2017). Information about the seasonal distribution of fin whales in 
the North Pacific has been obtained from the detection of fin whale 
calls by bottom-mounted, offshore hydrophone arrays along the U.S. 
Pacific coast, in the central North Pacific, and in the western 
Aleutian Islands (Moore et al. 1998, 2006; Watkins et al. 2000a,b; 
Stafford et al. 2007, 2009). Fin whale calls are recorded in the North 
Pacific year-round, including the GOA (e.g., Moore et al. 2006; 
Stafford et al. 2007, 2009; Edwards et al. 2015). Near the Alaska 
Peninsula in the western GOA, the number of calls received peaked in 
May-August, with few calls during the rest of the year (Moore et al. 
1998). In the central North Pacific, the GOA, and the Aleutian Islands, 
call rates peak during fall and winter (Moore et al. 1998, 2006; 
Watkins et al. 2000a,b; Stafford et al. 2009).
    Rice and Wolman (1982) encountered 19 fin whales during surveys in 
the GOA, including 10 aggregated near Middleton Island on 1 July 1980. 
During surveys from the Kenai Peninsula to the central Aleutian 
Islands, fin whales were most abundant near the Semidi Islands and 
Kodiak Island (Zerbini et al. 2006). Numerous sightings of fin whales 
were also seen between the Semidi Islands and Kodiak Island during 
surveys by Waite (2003). Fin whale sightings around Kodiak Island were 
most numerous along the western part of the island in Uyak Bay and 
Kupreanof Straits, and in Marmot Bay (Wynne and Witteveen 2005; Baraff 
et al. 2005). Fin whales were sighted around Kodiak Island year-round, 
but most sightings were made in the spring and summer (Wynne and 
Witteveeen 2005). A BIA for fin whale feeding has been designated 
southward from the Kenai Peninsula inshore of the Kodiak Archipelago 
and along the Alaska Peninsula to include the Semidi Islands (Ferguson 
et al. 2015), overlapping with a proportion of the proposed survey 
area. Densities of fin whales are highest in this area during June 
through August.
    Rone et al. (2017) reported 24 fin whale sightings (64 animals) in 
2009, two hundred fin whale sightings (392 animals) in 2013, and 48 fin 
whale sightings (69 animals) in 2015 in the U.S. Navy training area 
east of Kodiak. That study also provided an abundance estimate of 3168 
for this area. The density and abundance estimates were not corrected 
for missed animals. Fin whales were also frequently detected 
acoustically throughout the year during all years (2011-2015) of fixed-
PAM studies in this area and detections occurred at all shelf, slope, 
and seamount sites (Baumann-Pickering et al. 2012; Debich et al. 2013; 
Rice et al. 2015). Fin whales were the second most frequently sighted 
cetacean during the L-DEO seismic survey conducted in the summer of 
2011 in the same area as the currently proposed survey, comprising

[[Page 14208]]

15.2 percent of all cetacean sightings (RPS 2011). There were 28 
sightings of this species, representing 79 animals during the 37 days 
of monitoring. The average group size was three and the maximum group 
size was 10. Fin whales are likely to be common in the proposed survey 
area.
Blue Whale (Balaenoptera musculus)
    The blue whale has a cosmopolitan distribution and tends to be 
pelagic, only coming nearshore to feed and possibly to breed (Jefferson 
et al. 2015). Blue whale migration is less well defined than for some 
other rorquals, and their movements tend to be more closely linked to 
areas of high primary productivity, and hence prey, to meet their high 
energetic demands (Branch et al. 2007). Generally, blue whales are 
seasonal migrants between high latitudes in the summer, where they 
feed, and low latitudes in the winter, where they mate and give birth 
(Lockyer and Brown 1981). Some individuals may stay in low or high 
latitudes throughout the year (Reilly and Thayer 1990; Watkins et al. 
2000b).
    Although it has been suggested that there are at least five 
subpopulations in the North Pacific (Reeves et al. 1998), analysis of 
calls monitored from the U.S. Navy Sound Surveillance System (SOSUS) 
and other offshore hydrophones (e.g., Stafford et al. 1999, 2001, 2007; 
Watkins et al. 2000a; Stafford 2003) suggests that there are two 
separate populations: one in the eastern and one in the central North 
Pacific (Carretta et al. 2017). The Eastern North Pacific Stock 
includes whales that feed primarily off California from June-November 
and winter off Central America (Calambokidis et al. 1990; Mate et al. 
1999). The Central North Pacific Stock feeds off Kamchatka, south of 
the Aleutians and in the Gulf of Alaska during summer (Stafford 2003; 
Watkins et al. 2000b), and migrates to the western and central Pacific 
(including Hawaii) to breed in winter (Stafford et al. 2001; Carretta 
et al. 2017). The status of these two populations could differ 
substantially, as little is known about the population size in the 
western North Pacific (Branch et al. 2016).
    In the North Pacific, blue whale calls are detected year-round 
(Stafford et al. 2001, 2009; Moore et al. 2002a, 2006; Monnahan et al. 
2014). Stafford et al. (2009) reported that sea-surface temperature is 
a good predictor variable for blue whale call detections in the North 
Pacific. In the GOA, no detections of blue whales had been made since 
the late 1960s (NOAA 2004b; Calambokidis et al. 2009) until blue whale 
calls were recorded in the area during 1999-2002 (Stafford 2003; 
Stafford and Moore 2005; Moore et al. 2006; Stafford et al. 2007). Call 
types from both northeastern and northwestern Pacific blue whales were 
recorded from July through December in the GOA, suggesting that two 
stocks used the area at that time (Stafford 2003; Stafford et al. 
2007). Call rates peaked from August through November (Moore et al. 
2006). More recent acoustic studies using fixed PAM have confirmed the 
presence of blue whales from both the Central and Northeast Pacific 
stocks in the Gulf of Alaska concurrently (Baumann-Pickering et al. 
2012; Debich et al. 2013; Rice et al. 2015). Blue whale calls were 
recorded in all months; at all shelf, slope, and seamount sites; and 
during all years (2011-2015) of those studies.
    In July 2004, three blue whales were sighted in the GOA. The first 
blue whale was seen on 14 July ~185 km southeast of PWS. Two more blue 
whales were seen ~275 km southeast of PWS (NOAA 2004b; Calambokidis et 
al. 2009). These whales were thought to be part of the California 
feeding population (Calambokidis et al. 2009). Western blue whales are 
more likely to occur in the western portion of the GOA, southwest of 
Kodiak, where their calls have been detected (see Stafford 2003). Two 
blue whale sightings were also made in the Aleutians in August 2004 
(Calambokidis et al. 2009). No blue whales were seen during surveys of 
the western GOA by Zerbini et al. (2006).
    Rone et al. (2017) reported no blue whale sightings in 2009, five 
blue whale sightings (seven animals) in 2013, and 13 blue whale 
sightings (13 animals) in 2015 in the U.S. Navy training area east of 
Kodiak. Blue whales were not observed during the L-DEO seismic survey 
conducted in the summer of 2011 in the same area as the currently 
proposed survey (RPS 2011).

Odontocetes

Sperm Whale (Physeter macrocephalus)
    The sperm whale is the largest of the toothed whales, with an 
extensive worldwide distribution from the edge of the polar pack ice to 
the Equator (Whitehead 2009). Sperm whale distribution is linked to its 
social structure: Mixed groups of adult females and juveniles of both 
sexes generally occur in tropical and subtropical waters at latitudes 
less than ~40[deg] (Whitehead 2009). After leaving their female 
relatives, males gradually move to higher latitudes, with the largest 
males occurring at the highest latitudes and only returning to tropical 
and subtropical regions to breed. Sperm whales generally are 
distributed over large areas that have high secondary productivity and 
steep underwater topography, in waters at least 1000 m deep (Jaquet and 
Whitehead 1996). They are often found far from shore but can be found 
closer to oceanic islands that rise steeply from deep ocean waters 
(Whitehead 2009).
    Most of the information regarding sperm whale distribution in the 
GOA (especially the eastern GOA) and southeast Alaska has come from 
observations from fishermen and reports from fisheries observers aboard 
commercial fishing vessels (e.g., Dahlheim 1988). Fishery observers 
have identified interactions (e.g., depredation) between longline 
vessels and sperm whales in the GOA and southeast Alaska since at least 
the mid-1970s (e.g., Hill et al. 1999; Straley et al. 2005; Sigler et 
al. 2008), with most interactions occurring in the West Yakutat and 
East Yakutat/Southeast regions (Perez 2006; Hanselman et al. 2008). 
Sigler et al. (2008) noted high depredation rates in West Yakutat, East 
Yakutat/Southeast region, as well as the central GOA. Hill et al. 
(1999) found that most interactions in the GOA occurred to the east of 
Kodiak Island, even though there was substantial longline effort in 
waters to the west of Kodiak. Mellinger et al. (2004a) also noted that 
sperm whales occurred less often west of Kodiak Island.
    Sperm whales are commonly sighted during surveys in the Aleutians 
and the central and western GOA (e.g., Forney and Brownell 1996; Moore 
2001; Waite 2003; Wade et al. 2003; Zerbini et al. 2004; Barlow and 
Henry 2005; Ireland et al. 2005; Straley et al. 2005). Waite (2003) and 
Wade et al. (2003) noted an average group size of 1.2 in the western 
GOA. In contrast, there are fewer reports on the occurrence of sperm 
whales in the eastern GOA (e.g., Rice and Wolman 1982; Mellinger et al. 
2004a; MacLean and Koski 2005; Rone et al. 2010). Rone et al. (2017) 
reported no sperm whale sightings in 2009, 19 sperm whale sightings (22 
animals) in 2013, and 27 sperm whale sightings (45 animals) in 2015 in 
the U.S. Navy training area east of Kodiak. Additionally, there were 
241 acoustic encounters with sperm whales during the 2013 towed-
hydrophone survey in that study (Rone et al. 2014). Sperm whales were 
also frequently detected acoustically throughout the year during all 
years (2011-2015) of fixed-PAM studies in this area and detections 
occurred at all shelf, slope, and seamount sites, but they were less 
common at the shelf site near Kenai Peninsula and most common on the

[[Page 14209]]

slope (Baumann-Pickering et al. 2012; Debich et al. 2013; Rice et al. 
2015).
    Rone et al. (2017) provided an abundance estimate (uncorrected for 
missed animals) for the area of 129 sperm whales, most of which were 
found in slope waters. Sperm whales were not observed during the L-DEO 
seismic survey conducted in the summer of 2011 in the same area as the 
currently proposed survey (RPS 2011).
Cuvier's Beaked Whale (Ziphius cavirostris)
    Cuvier's beaked whale is the most widespread of the beaked whales, 
occurring in almost all temperate, subtropical, and tropical waters and 
even some sub-polar and polar waters (MacLeod et al. 2006). It is 
likely the most abundant of all beaked whales (Heyning and Mead 2009). 
Cuvier's beaked whale is found in deep water over and near the 
continental slope (Jefferson et al. 2015).
    Cuvier's beaked whale ranges north to the GOA, including southeast 
Alaska, the Aleutian Islands, and the Commander Islands (Rice 1986, 
1998). Most reported sightings have been in the Aleutian Islands (e.g., 
Leatherwood et al. 1983; Forney and Brownell 1996; Brueggeman et al. 
1987). Waite (2003) reported a single sighting of four Cuvier's beaked 
whales at the shelf break east of Kodiak Island during the summer of 
2003 and one stranded on Kodiak Island in January 1987 (Foster and Hare 
1990). There was one sighting of a single Cuvier's beaked whale during 
a 2013 survey in the U.S. Navy training area east of Kodiak, but none 
during the 2009 and 2015 surveys in that region (Rone et al. 2017). 
There were also five sightings (eight animals) of unidentified beaked 
whales during the 2013 survey and none during the other years. 
Additionally, there were 34 acoustic encounters with Cuvier's beaked 
whales during the 2013 towed-hydrophone survey in that study (Rone et 
al. 2014). Cuvier's beaked whales were detected occasionally at deep-
water sites (900-1,000 m) during the 2011-2015 fixed-PAM studies in the 
U.S. Navy training area. They were infrequently detected on the slope 
site but more commonly detected at Pratt and Quinn seamounts. 
Detections occurred May to July 2014 at Pratt Seamount and October 2014 
to March 2015 at Quinn Seamount in one of those studies (Rice et al. 
2015). Beaked whales were not observed during the L-DEO seismic survey 
conducted in the summer of 2011 in the same area as the currently 
proposed survey (RPS 2011).
Stejneger's Beaked Whale (Mesoplodon stejnegeri)
    Stejneger's beaked whale occurs in subarctic and cool temperate 
waters of the North Pacific (Mead 1989). Most records are from Alaskan 
waters, and the Aleutian Islands appear to be its center of 
distribution (Mead 1989; Wade et al. 2003). There have been no 
confirmed sightings of Stejneger's beaked whale in the GOA since 1986 
(Wade et al. 2003). However, they have been detected acoustically in 
the Aleutian Islands during summer, fall, and winter (Baumann-Pickering 
et al. 2014) and were detected year-round at deep-water sites during 
the 2011-2015 fixed-PAM studies in the U.S. Navy training area east of 
Kodiak (Baumann-Pickering et al. 2012; Debich et al. 2013; Rice et al. 
2015). In contrast to Cuvier's beaked whales, which were more prevalent 
at seamounts, Stejneger's beaked whales were detected most frequently 
at the slope site, with peak detections in September and October 
(Debich et al. 2013; Rice et al. 2015). There were no sightings of 
Stejneger's beaked whales during three years of surveys (2009, 2013, 
2015) in this area (Rone et al. 2017). However, there were five 
sightings (eight animals) of unidentified beaked whales during the 2013 
survey. Additionally, there were six acoustic encounters with 
Stejneger's beaked whales during the 2013 towed-hydrophone survey in 
that study (Rone et al. 2014). Beaked whales were not observed during 
the L-DEO seismic survey conducted in the summer of 2011 in the same 
area as the currently proposed survey (RPS 2011).
Baird's Beaked Whale (Berardius bairdii)
    Baird's beaked whale has a fairly extensive range across the North 
Pacific north of 30[deg] N, and strandings have occurred as far north 
as the Pribilof Islands (Rice 1986). Two forms of Baird's beaked whales 
have been recognized--the common slate-gray form and a smaller, rare 
black form (Morin et al. 2017). The gray form is seen off Japan, in the 
Aleutians, and on the west coast of North America, whereas the black 
from has been reported for northern Japan and the Aleutians (Morin et 
al. 2017). Recent genetic studies suggest that the black form could be 
a separate species (Morin et al. 2017).
    Baird's beaked whale is currently divided into three distinct 
stocks: Sea of Japan, Okhotsk Sea, and Bering Sea/eastern North Pacific 
(Balcomb 1989; Reyes 1991). Baird's beaked whales sometimes are seen 
close to shore, but their primary habitat is over or near the 
continental slope and oceanic seamounts in waters 1,000-3,000 m deep 
(Jefferson et al. 1993; Kasuya and Ohsumi 1984; Kasuya 2009).
    Baird's beaked whale is migratory, arriving in the Bering Sea in 
the spring, and remaining there throughout the summer; the winter 
distribution is unknown (Kasuya 2002). There are numerous sighting 
records from the central GOA to the Aleutian Islands and the southern 
Bering Sea (Leatherwood et al. 1983; Kasuya and Ohsumi 1984; Forney and 
Brownell 1996; Brueggeman et al. 1987; Moore et al. 2002b; Waite 2003; 
Wade et al. 2003). There were seven sightings of Baird's beaked whales 
(58 animals) during a 2013 survey in the U.S. Navy training area east 
of Kodiak (Rone et al. 2017). Additionally, there were nine acoustic 
encounters with Baird's beaked whales during the 2013 towed-hydrophone 
survey in that study (Rone et al. 2014). There were also five sightings 
(eight animals) of unidentified beaked whales during that survey. No 
beaked whales were observed in 2009 or 2015 surveys in the same area 
(Rone et al. 2017). Baird's beaked whales were detected acoustically 
during fixed-PAM studies in this area during the 2011-2012 and 2012-
2013 studies but not in 2014-2015 (Baumann-Pickering et al. 2012; 
Debich et al. 2013; Rice et al. 2015). They were detected regularly at 
the slope site from November through and January and at the Pratt 
Seamount site during most months. Beaked whales were not observed 
during the L-DEO seismic survey conducted in the summer of 2011 in the 
same area as the currently proposed survey (RPS 2011).
Pacific White-Sided Dolphin (Lagenorhynchus obliquidens)
    The Pacific white-sided dolphin is found throughout the temperate 
North Pacific, in a relatively narrow distribution between 38[deg] N 
and 47[deg] N (Brownell et al. 1999). It is common both on the high 
seas and along the continental margins (Leatherwood et al. 1984; 
Dahlheim and Towell 1994; Ferrero and Walker 1996). Pacific white-sided 
dolphins often associate with other species, including cetaceans 
(especially Risso's and northern right whale dolphins; Green et al. 
1993), pinnipeds, and seabirds.
    Pacific white-sided dolphins were seen throughout the North Pacific 
during surveys conducted during 1983-1990 (Buckland et al. 1993; 
Miyashita 1993b). During winter, this species is most abundant in 
California slope and offshore areas; as northern marine waters begin to 
warm in the spring, it appears to move north to slope and

[[Page 14210]]

offshore waters off Oregon/Washington (Green et al. 1992, 1993; Forney 
1994; Forney et al. 1995; Buchanan et al. 2001; Barlow 2003). During 
the summer, Pacific white-sided dolphins occur north into the GOA and 
west to Amchitka in the Aleutian Islands, but rarely in the southern 
Bering Sea (Allen and Angliss 2010). Moore et al. (2002b) documented a 
single sighting of eight Pacific white-sided dolphins in the southeast 
Bering Sea along the Alaska Peninsula. Sightings in the GOA and 
Aleutian Islands have been documented in the summer by Waite (2003) and 
Wade et al. (2003), and in the spring to the southeast of Kodiak Island 
by Rone et al. (2010). Dahlheim and Towell (1994) reported sightings 
for southeast Alaska. There was one sighting of 60 Pacific white-sided 
dolphins in 2009, no sightings in 2013, and 10 sightings of Pacific 
white-sided dolphins (986 animals) in 2015 during surveys in the U.S. 
Navy training area east of Kodiak (Rone et al. 2017). Pacific white-
sided dolphins were not observed during the L-DEO seismic survey 
conducted in the summer of 2011 in the same area as the currently 
proposed survey (RPS 2011), but there was one sighting of two 
unidentified small odontocetes.
Risso's Dolphin (Grampus griseus)
    Risso's dolphin is primarily a tropical and mid-temperate species 
distributed worldwide (Kruse et al. 1999). It occurs between 60[deg] N 
and 60[deg] S, where surface water temperatures are at least 10[deg] C 
(Kruse et al. 1999). Water temperature appears to be an important 
factor affecting its distribution (Kruse et al. 1999). Although it 
occurs from coastal to deep water, it shows a strong preference for 
mid-temperate waters of the continental shelf and slope (Jefferson et 
al. 2014).
    Throughout the region from California to Washington, the 
distribution and abundance of Risso's dolphins are highly variable, 
presumably in response to changing oceanographic conditions on both 
annual and seasonal time scales (Forney and Barlow 1998; Buchanan et 
al. 2001; Becker 2007). Water temperature appears to be an important 
factor affecting their distribution (Kruse et al. 1999; see also Becker 
2007). Like the Pacific white-sided dolphin, Risso's dolphin is 
believed to make seasonal north-south movements related to water 
temperature, spending colder winter months off California and moving 
north to waters off Oregon/Washington during the spring and summer as 
northern waters begin to warm (Green et al. 1992, 1993; Buchanan et al. 
2001; Barlow 2003; Becker 2007). Risso's dolphins are uncommon to rare 
in the GOA. Risso's dolphins have been sighted near Chirikof Island 
(southwest of Kodiak Island) and offshore in the GOA (Consiglieri et 
al. 1980; Braham 1983). They were detected acoustically once, in 
January 2013, near Pratt Seamount during fixed-PAM studies from 2011-
2015 in the U.S. Navy training area (Debich et al. 2013). The DoN 
(2014) considers this species to be only an occasional visitor to their 
GOA training area. Risso's dolphins were not observed during the L-DEO 
seismic survey conducted in the summer of 2011 in the same area as the 
currently proposed survey (RPS 2011). There was one sighting of two 
unidentified small odontocetes.
Killer Whale (Orcinus orca)
    The killer whale is cosmopolitan and globally fairly abundant; it 
has been observed in all oceans of the World (Ford 2009). It is very 
common in temperate waters and also frequents tropical waters, at least 
seasonally (Heyning and Dahlheim 1988). High densities of the species 
occur in high latitudes, especially in areas where prey is abundant. 
Killer whale movements generally appear to follow the distribution of 
their prey, which includes marine mammals, fish, and squid.
    Of eight killer whale stocks currently recognized in the Pacific 
U.S., six occur in Alaskan waters: (1) The Eastern North Pacific Alaska 
Resident Stock, from southeast Alaska to the Aleutians and Bering Sea, 
(2) the Eastern North Pacific Northern Resident Stock, from B.C. 
through parts of southeast Alaska, (3) the Eastern North Pacific Gulf 
of Alaska, Aleutian Islands, and Bering Sea Transient Stock, from PWS 
through to the Aleutians and Bering Sea, (4) the AT1 Transient Stock, 
from PWS through the Kenai Fjords, (5) the West Coast Transient Stock, 
from California through southeast Alaska, and (6) the Offshore Stock, 
from California through Alaska. The AT1 Transient Stock is considered 
depleted under the MMPA and therefore a strategic stock. Movements of 
resident groups between different geographic areas have also been 
documented (Leatherwood et al. 1990; Dahlheim et al. 1997; Matkin et 
al. 1997, 1999 in Allen and Angliss 2010). In the proposed study area, 
individuals from one resident stock (Eastern North Pacific Alaska 
Resident Stock), the North Pacific Offshore Stock, and one transient 
stock (Eastern North Pacific Gulf of Alaska, Aleutian Islands, and 
Bering Sea Transient Stock), could be encountered during the survey. 
AT1 transients have only ever been seen in Prince William Sound and in 
the Kenai Fjords region (Muto et al., 2018; Matkin et al 2008). 
Therefore, while the stock is present in the Gulf of Alaska, the 
limited range of the stock and the fact that this range does not 
overlap with L-DEO's proposed survey means take is not likely to occur 
for the AT1 stock of transient killer whales.
    During surveys of the western GOA and Aleutian Islands, transient 
killer whale densities were higher south of the Alaska Peninsula 
between the Shumagin Islands and the eastern Aleutians than in other 
areas (Wade et al. 2003; Zerbini et al. 2007). They were not seen 
between the Shumagin Islands and the eastern side of Kodiak Island 
during surveys in 2001-2003, but they were sighted there during earlier 
surveys (e.g., Dahlheim 1997 in Zerbini et al. 2007). Resident killer 
whales were most abundant near Kodiak Island, around Umnak and Unalaska 
Islands in the eastern Aleutians, and in Seguam Pass in the central 
Aleutians (Wade et al. 2003; Zerbini et al. 2007). No residents were 
seen between 156[deg] W and 164[deg] W, south of the Alaska Peninsula 
(Zerbini et al. 2007).
    Little is known about offshore killer whales in the GOA, but they 
could be encountered during the proposed survey. During summer surveys 
of the western GOA and Aleutian Islands in 2001-2003, two sightings of 
offshore killer whales were made, one northeast of Unalaska Island and 
another one south of Kodiak Island near the Trinity Islands (Wade et 
al. 2003; Zerbini et al. 2007). As the groups sighted were large, it 
suggests the number of offshore killer whales in the area is relatively 
high (Zerbini et al. 2007). Dahlheim et al. (2008b) encountered groups 
of 20-60 killer whales in western Alaska; offshore killer whales 
encountered near Kodiak Island and the eastern Aleutians were also 
sighted in southeast Alaska and California. A group of at least 54 
offshore killer whales was sighted in July 2003 during a survey in the 
eastern Aleutian Islands (Matkin et al. 2007).
    Rone et al. (2017) reported six killer whale sightings (119 
animals) in 2009, 21 killer whale sightings (138 animals) in 2013, and 
10 killer whale sightings (73 animals) in 2015 in the U.S. Navy 
training area east of Kodiak. Additionally, there were 32 acoustic 
encounters with killer whales and three acoustic encounters with 
offshore killer whales (based on known differences in their acoustic 
signals) during the 2013 towed-hydrophone survey in that study (Rone et 
al. 2014). Killer whales were detected acoustically sporadiacally 
throughout the year at shelf, slope, and seamount sites in the U.S. 
Navy training area (Baumann-Pickering et al. 2012;

[[Page 14211]]

Debich et al. 2013). Rone et al. (2017) an abundance estimate 
(uncorrected for missed animals) for the area of 899 killer whales, 
most of which were found in slope waters. There was one sighting of a 
single killer whale during the L-DEO seismic survey conducted in the 
summer of 2011 in the same area as the currently proposed survey (RPS 
2011).
Dall's Porpoise (Phocoenoides dalli)
    Dall's porpoise is only found in the North Pacific and adjacent 
seas. It is widely distributed across the North Pacific over the 
continental shelf and slope waters, and over deep (>2,500 m) oceanic 
waters (Hall 1979), ranging from ~30-62[deg] N (Jefferson et al. 2015). 
In general, this species is common throughout its range (Buckland et 
al. 1993). It is known to approach vessels to bowride (Jefferson 2009).
    Dall's porpoise occurs throughout Alaska; the only apparent gaps in 
distribution in Alaskan waters south of the Bering Strait are for upper 
Cook Inlet and the Bering Sea shelf. Using a population estimate based 
on vessel surveys during 1987-1991, and correcting for the tendency of 
this species to approach vessels, which Turnock and Quinn (1991) 
suggested resulted in inflated abundance estimates perhaps by as much 
as five times, a population estimate of 83,400 was calculated for the 
Alaska stock of Dall's porpoise. Because this estimate is more than 
eight years old, NMFS considers it to be unreliable and reported that 
there are no reliable abundance estimates available for the Alaska 
Stock of this species when it was last reviewed (Muto et al. 2016).
    Numerous studies have documented the occurrence of Dall's porpoise 
in the Aleutian Islands and western GOA (Forney and Brownell 1996; 
Moore 2001; Wade et al. 2003; Waite 2003; Baraff et al. 2005; Ireland 
et al. 2005) as well as in the Bering Sea (Moore et al. 2002b). Dall's 
porpoise was one of the most frequently sighted species during summer 
seismic surveys in the central and eastern GOA and southeast Alaska 
(MacLean and Koski 2005; Hauser and Holst 2009). Rone et al. (2017) 
reported 10 Dall's porpoise sightings (59 animals) in 2009, 337 Dall's 
porpoise sightings (907 animals) in 2013, and 98 Dall's porpoise 
sightings (391 animals) in 2015 in the U.S. Navy training area east of 
Kodiak. Additionally, there were three acoustic encounters with Dall's 
porpoise during the 2013 towed-hydrophone survey in that study (Rone et 
al. 2014). Rone et al. (2017) provided an abundance estimate for the 
area of 15,423 Dall's porpoises. This estimate was uncorrected for 
missed animals and did not account for their propensity to approach 
vessels. Dall's porpoise was the second most frequently sighted 
cetacean during the L-DEO seismic survey conducted in the summer of 
2011 in the same area as the currently proposed survey, comprising 14.1 
percent of all cetacean sightings (RPS 2011). There were 26 sightings 
of this species, representing 227 animals during the 37 days of 
monitoring. The average group size was nine and the largest group size 
was 35.
Harbor Porpoise (Phocoena phocoena)
    The harbor porpoise inhabits temperate, subarctic, and arctic 
waters. It is typically found in shallow water (<100 m) nearshore but 
is occasionally sighted in deeper offshore water (Jefferson et al. 
2015); abundance declines linearly as depth increases (Barlow 1988). In 
the eastern North Pacific, its range extends from Point Barrow, Alaska, 
to Point Conception, California.
    In Alaska, there are three separate stocks of harbor porpoise: 
Southeast Alaska, GOA, and Bering Sea. The Southeast Alaska Stock 
occurs from northern B.C. to Cape Suckling, and the GOA Stock ranges 
from Cape Suckling to Unimak Pass. The population estimates for the 
Southeast Alaska, GOA, and Bering Sea stocks are 11,146, 31,046, and 
48,215, respectively (Muto et al. 2016). The Southeast Alaska stock is
    Harbor porpoise are seen regularly in the western GOA and Aleutian 
Islands (e.g., Wade et al. 2003; Waite 2003; Baraff et al. 2005; 
Ireland et al. 2005) and Bering Sea (Moore et al. 2002b). Harbor 
porpoises are also sighted in the eastern and central GOA and southeast 
Alaska (Dahlheim et al. 2000, 2008a; MacLean and Koski 2005; Rone et 
al. 2010). There were 30 sightings (89 animals) of harbor porpoise in 
2009, eight sightings (11 animals) of harbor porposie in 2013, and a 
single sighting of one harbor porpoise in 2015 during surveys in the 
U.S. Navy training area east of Kodiak (Rone et al. 2017). Harbor 
porpoise were not observed during the L-DEO seismic survey conducted in 
the summer of 2011 in the same area as the currently proposed survey 
(RPS 2011), but there was one sighting of two unidentified small 
odontocetes.

Pinnipeds

Northern Fur Seal (Callorhinus ursinus)
    The northern fur seal is endemic to the North Pacific Ocean and 
occurs from southern California to the Bering Sea, Okhotsk Sea, and 
Honshu Island, Japan (Muto et al. 2018). During the breeding season, 
most of the worldwide population of northern fur seals inhabits the 
Pribilof Islands in the southern Bering Sea (Lee et al. 2014; Muto et 
al. 2018). The rest of the population occurs at rookeries on Bogoslof 
Island in the Bering Sea, in Russia (Commander Islands, Robben Island, 
Kuril Islands), on San Miguel Island in southern California (NMFS 1993; 
Lee et al. 2014), and on the Farallon Islands off central California 
(Muto et al. 2018). In the United States, two stocks are recognized--
the Eastern Pacific and the California stocks (Muto et al. 2018). The 
Eastern Pacific stock ranges from the Pribilof Islands and Bogoslof 
Island in the Bering Sea during summer to California during winter 
(Muto et al. 2018).
    When not on rookery islands, northern fur seals are primarily 
pelagic but occasionally haul out on rocky shorelines (Muto et al. 
2018). During the breeding season, adult males usually come ashore in 
May-August and may sometimes be present until November; adult females 
are found ashore from June-November (Carretta et al. 2017; Muto et al. 
2018). After reproduction, northern fur seals spend the next 7-8 months 
feeding at sea (Roppel 1984). Once weaned, juveniles spend 2-3 years at 
sea before returning to rookeries. Animals may migrate to the GOA, off 
Japan, and the west coast of the United States (Muto et al. 2018). Pups 
travel through Aleutian passes and spend the first two years at sea 
before returning to their islands of origin.
    In November, adult females and pups leave the Pribilof Islands and 
migrate into the North Pacific Ocean to areas including offshore Oregon 
and Washington (Ream et al. 2005). Males usually migrate only as far 
south as the GOA (Kajimura 1984). Ream et al. (2005) showed that 
migrating females moved over the continental shelf as they migrated 
southeasterly. Instead of following depth contours, their travel 
corresponded with movements of the Alaska Gyre and the North Pacific 
Current (Ream et al. 2005). Their foraging areas were associated with 
eddies, the subarctic-subtropical transition region, and coastal mixing 
(Ream et al. 2005; Alford et al. 2005). Some juveniles and non-pregnant 
females may remain in the GOA throughout the summer (Calkins 1986).
    Robson et al. (2004) reported that female fur seals from St. Paul 
and St. George islands traveled in different directions. They also 
observed habitat separation among breeding sites on the same island 
(Robson et al. 2004). Lactating females from the same breeding site 
share a foraging area,

[[Page 14212]]

whereas females from different sites tend to forage in different areas 
(Robson et al. 2004). Females from both islands traveled for similar 
durations and maximum distances (Robson et al. 2004).
    Northern fur seals were seen throughout the North Pacific during 
surveys conducted during 1987-1990 (Buckland et al. 1993). Tracked 
adult male fur seals that were tagged on St. Paul Island in the Bering 
Sea in October 2009, wintered in the Bering Sea or northern North 
Pacific Ocean; females migrated to the GOA and the California Current 
(Sterling et al. 2014).
    A total of 42 northern fur seals was seen during 3767 km of 
shipboard surveys in the northwestern GOA during June-July 1987 
(Brueggeman et al. 1988). Leatherwood et al. (1983) reported 14 
sightings of 34 northern fur seals away from the breeding islands in 
the southeast Bering Sea during aerial surveys in 1982, mostly during 
July and August. No fur seals were seen during summer surveys in the 
GOA in 2004 and 2008 (MacLean and Koski 2005; Hauser and Holst 2009) or 
during spring surveys in 2009 (Rone et al. 2010). None of the 42 female 
northern fur seals tagged on St Paul Island between August-October 2007 
and 2008 traveled south of the Aleutian Islands (Kuhn et al. 2010). 
Rone et al. (2014) reported 78 northern fur seal sightings (83 animals) 
in 2013 in the U.S. Navy training area east of Kodiak. They also 
provided an abundance estimate (uncorrected for missed animals) for the 
area of 1770 northern fur seals. There were seven sightings, 
representing 7 northern fur seals, during the L-DEO seismic survey 
conducted in the summer of 2011 in the same area as the currently 
proposed survey (RPS 2011).
Steller Sea Lion (Eumetopias jubatus)
    The Steller sea lion occurs along the North Pacific Rim from 
northern Japan to California (Loughlin et al. 1984). They are 
distributed around the coasts to the outer shelf from northern Japan 
through the Kuril Islands and Okhotsk Sea, through the Aleutian 
Islands, central Bering Sea, southern Alaska, and south to California 
(NMFS 2016c). There are two stocks, or DPSs, of Steller sea lions--the 
Western and Eastern DPSs, which are divided at 144[deg] W longitude 
(NMFS 2016c). The Western DPS is listed as endangered and includes 
animals that occur in Japan and Russia (NMFS 2016c; Muto et al. 2017); 
the Eastern DPS was delisted from threatened in 2013 (NMFS 2013a). 
Critical habitat has been designated 20 nmi around all major haulouts 
and rookeries, as well as three large foraging areas (NMFS 2017b). The 
critical habitat of both stocks is currently under review in light of 
the delisting of the Eastern DPS (Muto et al. 2018). Critical habitat 
as well as ``no approach'' zones occur within the proposed study area. 
``No approach'' zones are restricted areas wherein no vessel may 
approach within 3 nmi (5.6 km) of listed rookeries (50 CFR 223.202). 
Only individuals from the Western DPS are expected to occur in the 
proposed survey area. The Eastern DPS is estimated at 41,638 (Muto et 
al. 2017) and appears to have increased at an annual rate of 4.76 
percent between 1989 and 2015 (Muto et al. 2018).
    Rookeries of Steller sea lions from the Western DPS are located on 
the Aleutian Islands and along the Gulf of Alaska, as well as the east 
coast of Kamchatka, Commander Islands, and Kuril Islands (Burkanov and 
Loughlin 2005; Fritz et al. 2016; Muto et al. 2017). Breeding adults 
occupy rookeries from late-May to early-July (NMFS 2008). Non-breeding 
adults use haulouts or occupy sites at the periphery of rookeries 
during the breeding season (NMFS 2008). Pupping occurs from mid-May to 
mid July (Pitcher and Calkins 1981) and peaks in June (Pitcher et al. 
2002). Territorial males fast and remain on land during the breeding 
season (NMFS 2008). Females with pups generally stay within 30 km of 
the rookeries in shallow (30-120 m) water when feeding (NMFS 2008). 
Tagged juvenile sea lions showed localized movements near shore (Briggs 
et al. 2005). Loughlin et al. (2003) reported that most (88 percent) 
at-sea movements of juvenile Steller sea lions in the Aleutian Islands 
were short (<15 km) foraging trips. The mean distance of juvenile sea 
lion trips at sea was 16.6 km and the maximum trip distance recorded 
was 447 km. Long-range trips represented 6 percent of all trips at sea, 
and trip distance and duration increase with age (Loughlin et al. 2003; 
Call et al. 2007). Although Steller sea lions are not considered 
migratory, foraging animals can travel long distances outside of the 
breeding season (Loughlin et al. 2003; Raum-Suryan et al. 2002).
    Steller sea lions are present in Alaska year-round, with centers of 
abundance in the GOA and Aleutian Islands. There are five major rookery 
sites within the study area in the northern GOA: Chirikof, Chowiet, 
Atkins, Chernabura islands, and Pinnacle Rock. There are also numerous 
haulout sites located within the study area (see Figure 1 in the IHA 
Application); most haulout sites on Kodiak Island (and within the study 
area) are used year-round (e.g., Wynne 2005). Counts are highest in 
late summer (Wynne 2005). Sea lion counts in the central GOA, including 
Kodiak Island, were reported to be declining between 1999 and 2003 
(Sease and Gudmundson 2002; Wynne 2005). Evidence suggests that counts 
in Alaska were lowest in 2002 and 2003, but between 2003 and 2016 pup 
and non-pup counts have increased by 2.19 percent per year and 2.24 
percent per year, respectively (Muto et al. 2018). These rates vary 
regionally, with the highest rates of increase in the eastern Gulf of 
Alaska and a steadily decreasing rate of increase heading west to the 
Aleutian Islands.
    Steller sea lions 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. In 2008, 19 sea lions were taken in the Kodiak 
Island region and 9 were taken along the South Alaska Peninsula (Wolfe 
et al. 2009). As of 2009, data on community subsistence harvests are no 
longer being collected consistently so no data are available. The most 
recent 5 years of data available (2004-2008) show an annual average 
catch of 172 steller sea lions for all areas in Alaska combined except 
the Pribilof Islands in the Bering Sea (Muto et al. 2018).
    There was one sighting of 18 Steller sea lions during the L-DEO 
seismic survey conducted in the summer of 2011 in the same area as the 
currently proposed survey (RPS 2011).
Northern Elephant Seal (Mirounga angustirostris)
    Northern elephant seals breed in California and Baja California, 
primarily on offshore islands (Stewart et al. 1994), from December-
March (Stewart and Huber 1993). Adult elephant seals engage in two long 
northward migrations per year, one following the breeding season, and 
another following the annual molt, with females returning earlier to 
molt (March-April) than males (July-August) (Stewart and DeLong 1995). 
Juvenile elephant seals typically leave the rookeries in April or May 
and head north, traveling an average of 900-1,000 km. Hindell and 
Perrin (2009) noted that traveling likely takes place in water depths 
>200 m.
    When not breeding, elephant seals feed at sea far from the 
rookeries, ranging as far north as 60[deg] N, into the GOA and along 
the Aleutian Islands (Le Boeuf et al. 2000). Some seals that were 
tracked via satellite-tags for no more than 224 days traveled distances 
in excess of 10,000 km during that time (Le Beouf et al. 2000). 
Northern elephant

[[Page 14213]]

seals that were satellite-tagged at a California rookery have been 
recorded traveling as far west as ~166.5-172.5[deg] E (Le Boeuf et al. 
2000; Robinson et al. 2012; Robinson 2016 in OBIS 2018; Costa 2017 in 
OBIS 2018). Post-molting seals traveled longer and farther than post-
breeding seals (Robinson et al. 2012). Rone et al. (2014) reported 16 
northern fur seal sightings (16 animals) in a June-July 2013 survey in 
the U.S. Navy training area east of Kodiak. Northern elephant seal 
males could occur in the GOA throughout the year (Calkins 1986).
California Sea Lion (Zalophus californianus)
    The primary range of the California sea lion includes the coastal 
areas and offshore islands of the eastern North Pacific Ocean from BC, 
Canada, to central Mexico, including the Gulf of California (Jefferson 
et al. 2015). However, its distribution is expanding (Jefferson et al. 
2015), and its secondary range extends into the GOA where it is 
occasionally recorded (Maniscalco et al. 2004) and southern Mexico 
(Gallo-Reynoso and Sol[oacute]rzano-Velasco 1991). California sea lions 
are coastal animals that often haul out on shore throughout the year. 
King (1983) noted that sea lions are rarely found more than 16 km 
offshore. During fall and winter surveys off Oregon/Washington, mean 
distance from shore was ~13 km (Bonnell et al. 1992).
    California sea lion rookeries are on islands located in southern 
California, western Baja California, and the Gulf of California 
(Carretta et al. 2016). A single stock is recognized in U.S. waters: 
The U.S. Stock. Five genetically distinct geographic populations have 
been identified: (1) Pacific Temperate (includes rookeries in U.S. 
waters and the Coronados Islands to the south), (2) Pacific 
Subtropical, (3) Southern Gulf of California, (4) Central Gulf of 
California, and (5) Northern Gulf of California (Schramm et al. 2009). 
Animals from the Pacific Temperate population occur in the proposed 
project area. California sea lions that are sighted in Alaska are 
typically seen at Steller sea lion rookeries or haulouts, with most 
sightings occurring between March and May, although they can be found 
in the GOA year-round (Maniscalco et al. 2004).
Harbor Seal (Phoca vitulina)
    The harbor seal is distributed in the North Atlantic and North 
Pacific. Two subspecies occur in the Pacific: P.v. stejnegeri in the 
northwest Pacific Ocean and P.v. richardii in the eastern Pacific 
Ocean. Eastern Pacific harbor seals occur in nearshore, coastal, and 
estuarine areas ranging from Baja California, Mexico, north to the 
Pribilof Islands in Alaska (Muto et al. 2016). Harbor seals inhabit 
estuarine and coastal waters, hauling out on rocks, reefs, beaches, and 
glacial ice flows. They are generally non-migratory, but move locally 
with the tides, weather, season, food availability, and reproduction 
(Scheffer and Slipp 1944; Fisher 1952; Bigg 1969, 1981). Twelve stocks 
of harbor seals are recognized in Alaska (Muto et al. 2016). The 
proposed survey would take place within the range of three of these 
stocks: North Kodiak, South Kodiak, and Cook Inlet/Shelikof Strait 
stocks. Nearby stocks are the Aleutian Islands, Prince William Sound, 
and Glacier Bay/Icy Strait stocks. There are two stocks in the Bering 
Sea (Bristol Bay and Pribilof Islands) and four stocks in southeast 
Alaska.
    Female harbor seals give birth to a single pup while hauled out on 
shore or on glacial ice flows; pups are born from May to mid-July. The 
mother and pup remain together until weaning occurs at 3-6 weeks 
(Bishop 1967; Bigg 1969). When molting, which occurs primarily in late 
August, seals spend the majority of the time hauled out on shore, 
glacial ice, or other substrates. Juvenile harbor seals can travel 
significant distances (525 km) to forage or disperse, whereas adults 
were generally found within 190 km of their tagging location in Prince 
William Sound, Alaska (Lowry et al. 2001). The smaller home range used 
by adults is suggestive of a strong site fidelity (Pitcher and Calkins 
1979; Pitcher and McAllister 1981; Lowry et al. 2001). Pups tagged in 
the GOA most commonly undertook multiple return trips of more than 75 
km from natal areas, followed by movements of <25 km from the natal 
area (Small et al. 2005). Pups tagged in Prince William Sound traveled 
a mean maximum distance of 43.2 km from their tagging location, whereas 
those tagged in the GOA moved a mean maximum distance of 86.6 km (Small 
et al. 2005).
    Harbor seals are an important subsistence resource for Alaska 
Natives in the northern GOA. In 2011-2012, 37 harbor seals were taken 
from the North Kodiak Stock and 126 harbor seals were taken from the 
South Kodiak Stock by communities on Kodiak Island (Muto et al. 2016). 
The number taken from the Cook Inlet/Shelikof Strait Stock for 2011-
2012 is unknown, but an average of 233 were taken from this stock 
annually during 2004-2008 (Muto et al. 2016).
    There was one sighting of nine harbor seals during the L-DEO 
seismic survey conducted in the summer of 2011 in the same area as the 
currently proposed survey (RPS 2011). Harbor seals could be encountered 
in the proposed survey area.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
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 whales)....  7 Hz to 35 kHz.
Mid-frequency (MF) cetaceans (dolphins, toothed   150 Hz to 160 kHz.
 whales, beaked whales, bottlenose whales).

[[Page 14214]]

 
High-frequency (HF) cetaceans (true porpoises,    275 Hz to 160 kHz.
 Kogia, river dolphins, cephalorhynchid,
 Lagenorhynchus cruciger & L. australis).
Phocid pinnipeds (PW) (underwater) (true seals).  50 Hz to 86 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions    60 Hz to 39 kHz.
 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) have the reasonable potential to co-occur with 
the proposed survey activities. Please refer to Table 1. Of the 16 
cetacean species that may be present, 7 are classified as low-frequency 
cetaceans (i.e., all mysticete species), 7 are classified as mid-
frequency cetaceans (i.e., all delphinid and ziphiid species and the 
sperm whale), and 2 are classified as high-frequency cetaceans (i.e., 
harbor porpoise and Kogia spp.).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a summary and discussion of the ways that 
components of the specified activity may impact marine mammals and 
their habitat. The Estimated Take by Incidental Harassment section 
later in this document includes a quantitative analysis of the number 
of individuals that are expected to be taken by this activity. The 
Negligible Impact Analysis and Determination section considers the 
content of this section, the Estimated Take by Incidental Harassment 
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.

Description of Active Acoustic Sound Sources

    This section contains a brief technical background on sound, 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 a discussion of the potential effects of the specified 
activity on marine mammals found later in this document.
    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 (Hz) 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 dB. 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 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]Pa\2\-s) 
represents the total energy contained within a pulse and considers both 
intensity and duration of exposure. Peak sound pressure (also referred 
to as zero-to-peak sound pressure or 0-p) 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. 
Another common metric is peak-to-peak sound pressure (pk-pk), which is 
the algebraic difference between the peak positive and peak negative 
sound pressures. Peak-to-peak pressure is typically approximately 6 dB 
higher than peak pressure (Southall et al., 2007).
    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 pulses produced by the 
airgun arrays 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. Ambient 
sound is defined as environmental background sound levels lacking a 
single source or point (Richardson et al., 1995), and 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 the following 
(Richardson et al., 1995):

[[Page 14215]]

     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient sound for frequencies between 200 Hz and 50 
kHz (Mitson, 1995). In general, ambient sound levels tend to increase 
with increasing wind speed and wave height. Surf sound becomes 
important near shore, with measurements collected at a distance of 8.5 
km from shore showing an increase of 10 dB in the 100 to 700 Hz band 
during heavy surf conditions;
     Precipitation: Sound from rain and hail impacting the 
water surface can become an important component of total sound at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times;
     Biological: 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; and
     Anthropogenic: Sources of ambient sound related to human 
activity include transportation (surface vessels), dredging and 
construction, oil and gas drilling and production, seismic surveys, 
sonar, explosions, and ocean acoustic studies. 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. Sound from identifiable anthropogenic sources other than the 
activity of interest (e.g., a passing vessel) is sometimes termed 
background sound, as opposed to ambient sound.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--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 a given 
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.
    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 non-continuous (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 (such as 
those used by the U.S. Navy). 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.
    As described above, a Kongsberg EM 122 MBES, a Knudsen Chirp 3260 
SBP, and a Teledyne RDI 75 kHz Ocean Surveyor ADCP would be operated 
continuously during the proposed surveys, but not during transit to and 
from the survey areas. Due to the lower source level of the Kongsberg 
EM 122 MBES relative to the Langseth's airgun array (242 dB re 1 [mu]Pa 
[middot] m for the MBES versus a minimum of 258 dB re 1 [mu]Pa [middot] 
m (rms) for the 36 airgun array (NSF-USGS, 2011)), sounds from the MBES 
are expected to be effectively subsumed by the sounds from the airgun 
array. Thus, any marine mammal potentially exposed to sounds from the 
MBES would already have been exposed to sounds from the airgun array, 
which are expected to propagate further in the water. Each ping emitted 
by the MBES consists of eight (in water >1,000 m deep) or four (<1,000 
m) successive fan-shaped transmissions, each ensonifying a sector that 
extends 1[deg] fore-aft. Given the movement and speed of the vessel, 
the intermittent and narrow downward-directed nature of the sounds 
emitted by the MBES would result in no more than one or two brief ping 
exposures of any individual marine mammal, if any exposure were to 
occur.
    Due to the lower source levels of both the Knudsen Chirp 3260 SBP 
and the Teledyne RDI 75 kHz Ocean Surveyor ADCP relative to the 
Langseth's airgun array (maximum SL of 222 dB re 1 [mu]Pa [middot] m 
for the SBP and maximum SL of 224 dB re 1 [mu]Pa [middot] m for the 
ADCP, versus a minimum of 258 dB re 1 [mu]Pa [middot] m for the 36 
airgun array (NSF-USGS, 2011)), sounds from the SBP and ADCP are 
expected to be effectively subsumed by sounds from the airgun array. 
Thus, any marine mammal potentially exposed to sounds from the SBP and/
or the ADCP would already have been exposed to sounds from the airgun 
array, which are expected to propagate further in the water. As such, 
we conclude that the likelihood of marine mammal take resulting from 
exposure to sound from the MBES, SBP or ADCP (beyond that which is 
already quantified as a result of exposure to the airguns) is 
discountable and therefore we do not consider noise from the MBES, SBP 
or ADCP further in this analysis.

Acoustic Effects

    Here, we discuss the effects of active acoustic sources on marine 
mammals.
    Potential Effects of Underwater Sound--Please refer to the 
information given previously (``Description of Active Acoustic 
Sources'') regarding sound, characteristics of sound types, and

[[Page 14216]]

metrics used in this document. Anthropogenic sounds cover a broad range 
of frequencies and sound levels and can have a range of highly variable 
impacts on marine life, from none or minor to potentially severe 
responses, depending on received levels, duration of exposure, 
behavioral context, and various other factors. The potential effects of 
underwater sound from active acoustic sources can potentially result in 
one or more of the following: Temporary or permanent hearing 
impairment, non-auditory physical or physiological effects, behavioral 
disturbance, stress, and masking (Richardson et al., 1995; Gordon et 
al., 2004; Nowacek et al., 2007; Southall et al., 2007; G[ouml]tz et 
al., 2009). The degree of effect is intrinsically related to the signal 
characteristics, received level, distance from the source, and duration 
of the sound exposure. In general, sudden, high level sounds can cause 
hearing loss, as can longer exposures to lower level sounds. Temporary 
or permanent loss of hearing will occur almost exclusively for noise 
within an animal's hearing range. We first describe specific 
manifestations of acoustic effects before providing discussion specific 
to the use of airgun arrays.
    Richardson et al. (1995) described zones of increasing intensity of 
effect that might be expected to occur, in relation to distance from a 
source and assuming that the signal is within an animal's hearing 
range. First is the area within which the acoustic signal would be 
audible (potentially perceived) to the animal, but not strong enough to 
elicit any overt behavioral or physiological response. The next zone 
corresponds with the area where the signal is audible to the animal and 
of sufficient intensity to elicit behavioral or physiological 
responsiveness. Third is a zone within which, for signals of high 
intensity, the received level is sufficient to potentially cause 
discomfort or tissue damage to auditory or other systems. Overlaying 
these zones to a certain extent is the area within which masking (i.e., 
when a sound interferes with or masks the ability of an animal to 
detect a signal of interest that is above the absolute hearing 
threshold) may occur; the masking zone may be highly variable in size.
    We describe the more severe effects of certain non-auditory 
physical or physiological effects only briefly as we do not expect that 
use of airgun arrays are reasonably likely to result in such effects 
(see below for further discussion). Potential effects from impulsive 
sound sources can range in severity from effects such as behavioral 
disturbance or tactile perception to physical discomfort, slight injury 
of the internal organs and the auditory system, or mortality (Yelverton 
et al., 1973). Non-auditory physiological effects or injuries that 
theoretically might occur in marine mammals exposed to high level 
underwater sound or as a secondary effect of extreme behavioral 
reactions (e.g., change in dive profile as a result of an avoidance 
reaction) caused by exposure to sound include neurological effects, 
bubble formation, resonance effects, and other types of organ or tissue 
damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack, 
2007; Tal et al., 2015). The survey activities considered here do not 
involve the use of devices such as explosives or mid-frequency tactical 
sonar that are associated with these types of effects.
    Threshold Shift--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). Repeated sound exposure that 
leads to TTS could cause PTS. In severe cases of PTS, there can be 
total or partial deafness, while in most cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). In addition, other 
investigators have suggested that TTS is within the normal bounds of 
physiological variability and tolerance and does not represent physical 
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to 
constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several dBs above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al. 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulse sounds (such as airgun pulses as 
received close to the source) are at least 6 dB higher than the TTS 
threshold on a peak-pressure basis and PTS cumulative sound exposure 
level thresholds are 15 to 20 dB higher than TTS cumulative sound 
exposure level thresholds (Southall et al., 2007). Given the higher 
level of sound or longer exposure duration necessary to cause PTS as 
compared with TTS, it is considerably less likely that PTS could occur.
    For mid-frequency cetaceans in particular, potential protective 
mechanisms may help limit onset of TTS or prevent onset of PTS. Such 
mechanisms include dampening of hearing, auditory adaptation, or 
behavioral amelioration (e.g., Nachtigall and Supin, 2013; Miller et 
al., 2012; Finneran et al., 2015; Popov et al., 2016).
    TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. Few data 
on sound levels and durations necessary to elicit mild TTS have been 
obtained for marine mammals.
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS, and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to 
serious. For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that occurs during a time where ambient noise is lower and there 
are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts.
    Finneran et al. (2015) measured hearing thresholds in three captive 
bottlenose dolphins before and after exposure to ten pulses produced by 
a seismic airgun in order to study TTS induced after exposure to 
multiple pulses. Exposures began at relatively low levels and gradually 
increased over a period of several months, with the highest exposures 
at peak SPLs from 196 to 210 dB and cumulative (unweighted) SELs from 
193-195 dB.

[[Page 14217]]

No substantial TTS was observed. In addition, behavioral reactions were 
observed that indicated that animals can learn behaviors that 
effectively mitigate noise exposures (although exposure patterns must 
be learned, which is less likely in wild animals than for the captive 
animals considered in this study). The authors note that the failure to 
induce more significant auditory effects likely due to the intermittent 
nature of exposure, the relatively low peak pressure produced by the 
acoustic source, and the low-frequency energy in airgun pulses as 
compared with the frequency range of best sensitivity for dolphins and 
other mid-frequency cetaceans.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin, beluga whale, harbor porpoise, and Yangtze finless 
porpoise) exposed to a limited number of sound sources (i.e., mostly 
tones and octave-band noise) in laboratory settings (Finneran, 2015). 
In general, harbor porpoises have a lower TTS onset than other measured 
cetacean species (Finneran, 2015). Additionally, the existing marine 
mammal TTS data come from a limited number of individuals within these 
species. There are no data available on noise-induced hearing loss for 
mysticetes.
    Critical questions remain regarding the rate of TTS growth and 
recovery after exposure to intermittent noise and the effects of single 
and multiple pulses. Data at present are also insufficient to construct 
generalized models for recovery and determine the time necessary to 
treat subsequent exposures as independent events. More information is 
needed on the relationship between auditory evoked potential and 
behavioral measures of TTS for various stimuli. For summaries of data 
on TTS in marine mammals or for further discussion of TTS onset 
thresholds, please see Southall et al. (2007), Finneran and Jenkins 
(2012), Finneran (2015), and NMFS (2016a).
    Behavioral Effects--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 (e.g., 
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007; 
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not 
only among individuals but also within an individual, depending on 
previous experience with a sound source, context, and numerous other 
factors (Ellison et al., 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). 
Please see Appendices B-C of Southall et al. (2007) for a review of 
studies involving marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. As noted, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with 
captive marine mammals have showed pronounced behavioral reactions, 
including avoidance of loud sound sources (Ridgway et al., 1997). 
Observed responses of wild marine mammals to loud pulsed sound sources 
(typically seismic airguns or acoustic harassment devices) have been 
varied but often consist of avoidance behavior or other behavioral 
changes suggesting discomfort (Morton and Symonds, 2002; see also 
Richardson et al., 1995; Nowacek et al., 2007). However, many 
delphinids approach acoustic source vessels with no apparent discomfort 
or obvious behavioral change (e.g., Barkaszi et al., 2012).
    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. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely, and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Ng and Leung, 2003; Nowacek et al., 2004; Goldbogen et 
al., 2013a, b). Variations in dive behavior may reflect interruptions 
in biologically significant activities (e.g., foraging) or they may be 
of little biological significance. The impact of an alteration to dive 
behavior resulting from an acoustic exposure depends on what the animal 
is doing at the time of the exposure and the type and magnitude of the 
response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al.; 2004; Madsen et al., 2006; Yazvenko et al., 
2007). A determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Visual tracking, passive acoustic monitoring, and movement 
recording tags were used to quantify sperm whale behavior prior to, 
during, and following exposure to airgun arrays at received levels in 
the range 140-160 dB at distances of 7-13 km, following a phase-in of 
sound intensity and full array

[[Page 14218]]

exposures at 1-13 km (Madsen et al., 2006; Miller et al., 2009). Sperm 
whales did not exhibit horizontal avoidance behavior at the surface. 
However, foraging behavior may have been affected. The sperm whales 
exhibited 19 percent less vocal (buzz) rate during full exposure 
relative to post exposure, and the whale that was approached most 
closely had an extended resting period and did not resume foraging 
until the airguns had ceased firing. The remaining whales continued to 
execute foraging dives throughout exposure; however, swimming movements 
during foraging dives were 6 percent lower during exposure than control 
periods (Miller et al., 2009). These data raise concerns that seismic 
surveys may impact foraging behavior in sperm whales, although more 
data are required to understand whether the differences were due to 
exposure or natural variation in sperm whale behavior (Miller et al., 
2009).
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that respiration rates may 
either be unaffected or could increase, depending on the species and 
signal characteristics, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et 
al., 2007, 2016).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al., 
2000; Fristrup et al., 2003; Foote et al., 2004), while right whales 
have been observed to shift the frequency content of their calls upward 
while reducing the rate of calling in areas of increased anthropogenic 
noise (Parks et al., 2007). In some cases, animals may cease sound 
production during production of aversive signals (Bowles et al., 1994).
    Cerchio et al. (2014) used passive acoustic monitoring to document 
the presence of singing humpback whales off the coast of northern 
Angola and to opportunistically test for the effect of seismic survey 
activity on the number of singing whales. Two recording units were 
deployed between March and December 2008 in the offshore environment; 
numbers of singers were counted every hour. Generalized Additive Mixed 
Models were used to assess the effect of survey day (seasonality), hour 
(diel variation), moon phase, and received levels of noise (measured 
from a single pulse during each ten minute sampled period) on singer 
number. The number of singers significantly decreased with increasing 
received level of noise, suggesting that humpback whale breeding 
activity was disrupted to some extent by the survey activity.
    Castellote et al. (2012) reported acoustic and behavioral changes 
by fin whales in response to shipping and airgun noise. Acoustic 
features of fin whale song notes recorded in the Mediterranean Sea and 
northeast Atlantic Ocean were compared for areas with different 
shipping noise levels and traffic intensities and during a seismic 
airgun survey. During the first 72 h of the survey, a steady decrease 
in song received levels and bearings to singers indicated that whales 
moved away from the acoustic source and out of the study area. This 
displacement persisted for a time period well beyond the 10-day 
duration of seismic airgun activity, providing evidence that fin whales 
may avoid an area for an extended period in the presence of increased 
noise. The authors hypothesize that fin whale acoustic communication is 
modified to compensate for increased background noise and that a 
sensitization process may play a role in the observed temporary 
displacement.
    Seismic pulses at average received levels of 131 dB re 1 [mu]Pa\2\-
s caused blue whales to increase call production (Di Iorio and Clark, 
2010). In contrast, McDonald et al. (1995) tracked a blue whale with 
seafloor seismometers and reported that it stopped vocalizing and 
changed its travel direction at a range of 10 km from the acoustic 
source vessel (estimated received level 143 dB pk-pk). Blackwell et al. 
(2013) found that bowhead whale call rates dropped significantly at 
onset of airgun use at sites with a median distance of 41-45 km from 
the survey. Blackwell et al. (2015) expanded this analysis to show that 
whales actually increased calling rates as soon as airgun signals were 
detectable before ultimately decreasing calling rates at higher 
received levels (i.e., 10-minute SELcum of ~127 dB). 
Overall, these results suggest that bowhead whales may adjust their 
vocal output in an effort to compensate for noise before ceasing 
vocalization effort and ultimately deflecting from the acoustic source 
(Blackwell et al., 2013, 2015). These studies demonstrate that even low 
levels of noise received far from the source can induce changes in 
vocalization and/or behavior for mysticetes.
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Humpback whales showed avoidance behavior in the presence of an 
active seismic array during observational studies and controlled 
exposure experiments in western Australia (McCauley et al., 2000). 
Avoidance may be short-term, with animals returning to the area once 
the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; Stone et 
al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). Longer-term 
displacement is possible, however, which may lead to changes in 
abundance or distribution patterns of the affected species in the 
affected region if habituation to the presence of the sound does not 
occur (e.g., Bejder et al., 2006; Teilmann et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, marine mammal strandings 
(Evans and England, 2001). However, it should be noted that response to 
a perceived predator does not necessarily invoke flight (Ford and 
Reeves, 2008), and whether individuals are solitary or in groups may 
influence the response.

[[Page 14219]]

    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a five-day period did not cause any 
sleep deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    Stone (2015) reported data from at-sea observations during 1,196 
seismic surveys from 1994 to 2010. When large arrays of airguns 
(considered to be 500 in\3\ or more) were firing, lateral displacement, 
more localized avoidance, or other changes in behavior were evident for 
most odontocetes. However, significant responses to large arrays were 
found only for the minke whale and fin whale. Behavioral responses 
observed included changes in swimming or surfacing behavior, with 
indications that cetaceans remained near the water surface at these 
times. Cetaceans were recorded as feeding less often when large arrays 
were active. Behavioral observations of gray whales during a seismic 
survey monitored whale movements and respirations pre-, during and 
post-seismic survey (Gailey et al., 2016). Behavioral state and water 
depth were the best `natural' predictors of whale movements and 
respiration and, after considering natural variation, none of the 
response variables were significantly associated with seismic survey or 
vessel sounds.
    Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficiently to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    Auditory Masking--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) (Richardson et al., 1995; Erbe et al., 
2016). 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. The ability of a noise 
source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is man-made, it may be considered harassment 
when disrupting or altering critical behaviors. It is important to 
distinguish TTS and PTS, which persist after the sound exposure, from 
masking,

[[Page 14220]]

which occurs during the sound exposure. Because masking (without 
resulting in TS) is not associated with abnormal physiological 
function, it is not considered a physiological effect, but rather a 
potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al., 2000; 
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt 
et al., 2009). Masking can be reduced in situations where the signal 
and noise come from different directions (Richardson et al., 1995), 
through amplitude modulation of the signal, or through other 
compensatory behaviors (Houser and Moore, 2014). Masking can be tested 
directly in captive species (e.g., Erbe, 2008), but in wild populations 
it must be either modeled or inferred from evidence of masking 
compensation. There are few studies addressing real-world masking 
sounds likely to be experienced by marine mammals in the wild (e.g., 
Branstetter et al., 2013).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency 
ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand, 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.
    Masking effects of pulsed sounds (even from large arrays of 
airguns) on marine mammal calls and other natural sounds are expected 
to be limited, although there are few specific data on this. Because of 
the intermittent nature and low duty cycle of seismic pulses, animals 
can emit and receive sounds in the relatively quiet intervals between 
pulses. However, in exceptional situations, reverberation occurs for 
much or all of the interval between pulses (e.g., Simard et al. 2005; 
Clark and Gagnon 2006), which could mask calls. Situations with 
prolonged strong reverberation are infrequent. However, it is common 
for reverberation to cause some lesser degree of elevation of the 
background level between airgun pulses (e.g., Gedamke 2011; Guerra et 
al. 2011, 2016; Klinck et al. 2012; Guan et al. 2015), and this weaker 
reverberation presumably reduces the detection range of calls and other 
natural sounds to some degree. Guerra et al. (2016) reported that 
ambient noise levels between seismic pulses were elevated as a result 
of reverberation at ranges of 50 km from the seismic source. Based on 
measurements in deep water of the Southern Ocean, Gedamke (2011) 
estimated that the slight elevation of background levels during 
intervals between pulses reduced blue and fin whale communication space 
by as much as 36-51 percent when a seismic survey was operating 450-
2,800 km away. Based on preliminary modeling, Wittekind et al. (2016) 
reported that airgun sounds could reduce the communication range of 
blue and fin whales 2000 km from the seismic source. Nieukirk et al. 
(2012) and Blackwell et al. (2013) noted the potential for masking 
effects from seismic surveys on large whales.
    Some baleen and toothed whales are known to continue calling in the 
presence of seismic pulses, and their calls usually can be heard 
between the pulses (e.g., Nieukirk et al. 2012; Thode et al. 2012; 
Br[ouml]ker et al. 2013; Sciacca et al. 2016). As noted above, Cerchio 
et al. (2014) suggested that the breeding display of humpback whales 
off Angola could be disrupted by seismic sounds, as singing activity 
declined with increasing received levels. In addition, some cetaceans 
are known to change their calling rates, shift their peak frequencies, 
or otherwise modify their vocal behavior in response to airgun sounds 
(e.g., Di Iorio and Clark 2010; Castellote et al. 2012; Blackwell et 
al. 2013, 2015). The hearing systems of baleen whales are undoubtedly 
more sensitive to low-frequency sounds than are the ears of the small 
odontocetes that have been studied directly (e.g., MacGillivray et al. 
2014). The sounds important to small odontocetes are predominantly at 
much higher frequencies than are the dominant components of airgun 
sounds, thus limiting the potential for masking. In general, masking 
effects of seismic pulses are expected to be minor, given the normally 
intermittent nature of seismic pulses.

Ship Noise

    Vessel noise from the Langseth could affect marine animals in the 
proposed survey areas. Houghton et al. (2015) proposed that vessel 
speed is the most important predictor of received noise levels, and 
Putland et al. (2017) also reported reduced sound levels with decreased 
vessel speed. Sounds produced by large vessels generally dominate 
ambient noise at frequencies from 20 to 300 Hz (Richardson et al. 
1995). However, some energy is also produced at higher frequencies 
(Hermannsen et al. 2014); low levels of high-frequency sound from 
vessels has been shown to elicit responses in harbor porpoise (Dyndo et 
al. 2015). Increased levels of ship noise have been shown to affect 
foraging by porpoise (Teilmann et al. 2015; Wisniewska et al. 2018); 
Wisniewska et al. (2018) suggest that a decrease in foraging success 
could have long-term fitness consequences.
    Ship noise, through masking, can reduce the effective communication 
distance of a marine mammal if the frequency of the sound source is 
close to that used by the animal, and if the sound is present for a 
significant fraction of time (e.g., Richardson et al. 1995; Clark et 
al. 2009; Jensen et al. 2009; Gervaise et al. 2012; Hatch et al. 2012; 
Rice et al. 2014; Dunlop 2015; Erbe et al. 2015; Jones et al. 2017; 
Putland et al. 2017). In addition to the frequency and duration of the 
masking sound, the strength, temporal pattern, and location of the 
introduced sound also play a role in the extent of the masking 
(Branstetter et al. 2013, 2016; Finneran and Branstetter 2013; Sills et 
al. 2017). Branstetter et al. (2013) reported that time-domain metrics 
are also important in describing and predicting masking. In order to 
compensate for increased ambient noise, some cetaceans are known to 
increase the source levels of their calls in the presence of elevated 
noise levels from shipping, shift their peak frequencies, or otherwise 
change their vocal behavior (e.g., Parks et al. 2011, 2012, 2016a,b; 
Castellote et al. 2012; Melc[oacute]n et al. 2012; Azzara et al. 2013; 
Tyack and Janik 2013; Lu[iacute]s et al. 2014; Sairanen 2014; Papale et 
al. 2015; Bittencourt et al. 2016; Dahlheim and Castellote 2016; 
Gospi[cacute] and Picciulin 2016; Gridley et al. 2016; Heiler et al. 
2016; Martins et al. 2016; O'Brien et al. 2016; Tenessen and Parks 
2016). Harp seals did not increase their call frequencies in 
environments with increased low-frequency sounds (Terhune and Bosker 
2016). Holt et al. (2015) reported that changes in vocal

[[Page 14221]]

modifications can have increased energetic costs for individual marine 
mammals. A negative correlation between the presence of some cetacean 
species and the number of vessels in an area has been demonstrated by 
several studies (e.g., Campana et al. 2015; Culloch et al. 2016).
    Baleen whales are thought to be more sensitive to sound at these 
low frequencies than are toothed whales (e.g., MacGillivray et al. 
2014), possibly causing localized avoidance of the proposed survey area 
during seismic operations. Reactions of gray and humpback whales to 
vessels have been studied, and there is limited information available 
about the reactions of right whales and rorquals (fin, blue, and minke 
whales). Reactions of humpback whales to boats are variable, ranging 
from approach to avoidance (Payne 1978; Salden 1993). Baker et al. 
(1982, 1983) and Baker and Herman (1989) found humpbacks often move 
away when vessels are within several kilometers. Humpbacks seem less 
likely to react overtly when actively feeding than when resting or 
engaged in other activities (Krieger and Wing 1984, 1986). Increased 
levels of ship noise have been shown to affect foraging by humpback 
whales (Blair et al. 2016). Fin whale sightings in the western 
Mediterranean were negatively correlated with the number of vessels in 
the area (Campana et al. 2015). Minke whales and gray seals have shown 
slight displacement in response to construction-related vessel traffic 
(Anderwald et al. 2013).
    Many odontocetes show considerable tolerance of vessel traffic, 
although they sometimes react at long distances if confined by ice or 
shallow water, if previously harassed by vessels, or have had little or 
no recent exposure to ships (Richardson et al. 1995). Dolphins of many 
species tolerate and sometimes approach vessels (e.g., Anderwald et al. 
2013). Some dolphin species approach moving vessels to ride the bow or 
stern waves (Williams et al. 1992). Pirotta et al. (2015) noted that 
the physical presence of vessels, not just ship noise, disturbed the 
foraging activity of bottlenose dolphins. Sightings of striped dolphin, 
Risso's dolphin, sperm whale, and Cuvier's beaked whale in the western 
Mediterranean were negatively correlated with the number of vessels in 
the area (Campana et al. 2015).
    There are few data on the behavioral reactions of beaked whales to 
vessel noise, though they seem to avoid approaching vessels (e.g., 
W[uuml]rsig et al. 1998) or dive for an extended period when approached 
by a vessel (e.g., Kasuya 1986). Based on a single observation, Aguilar 
Soto et al. (2006) suggest foraging efficiency of Cuvier's beaked 
whales may be reduced by close approach of vessels.
    In summary, project vessel sounds would not be at levels expected 
to cause anything more than possible localized and temporary behavioral 
changes in marine mammals, and would not be expected to result in 
significant negative effects on individuals or at the population level. 
In addition, in all oceans of the world, large vessel traffic is 
currently so prevalent that it is commonly considered a usual source of 
ambient sound (NSF-USGS 2011).

Ship Strike

    Vessel collisions with marine mammals, or ship strikes, can result 
in death or serious injury of the animal. Wounds resulting from ship 
strike may include massive trauma, hemorrhaging, broken bones, or 
propeller lacerations (Knowlton and Kraus, 2001). An animal at the 
surface may be struck directly by a vessel, a surfacing animal may hit 
the bottom of a vessel, or an animal just below the surface may be cut 
by a vessel's propeller. Superficial strikes may not kill or result in 
the death of the animal. These interactions are typically associated 
with large whales (e.g., fin whales), which are occasionally found 
draped across the bulbous bow of large commercial ships upon arrival in 
port. Although smaller cetaceans are more maneuverable in relation to 
large vessels than are large whales, they may also be susceptible to 
strike. 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).
    Pace and Silber (2005) also found that the probability of death or 
serious injury increased rapidly with increasing vessel speed. 
Specifically, the predicted probability of serious injury or death 
increased from 45 to 75 percent as vessel speed increased from 10 to 14 
kn, and exceeded 90 percent at 17 kn. Higher speeds during collisions 
result in greater force of impact, but higher speeds also appear to 
increase the chance of severe injuries or death through increased 
likelihood of collision by pulling whales toward the vessel (Clyne, 
1999; Knowlton et al., 1995). In a separate study, Vanderlaan and 
Taggart (2007) analyzed the probability of lethal mortality of large 
whales at a given speed, showing that the greatest rate of change in 
the probability of a lethal injury to a large whale as a function of 
vessel speed occurs between 8.6 and 15 kn. 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, while the probability asymptotically 
increases toward one hundred percent above 15 kn.
    The Langseth travels at a speed of 5 kn (approximately 9.3 km/h) 
while towing seismic survey gear (LGL 2018). At this speed, both the 
possibility of striking a marine mammal and the possibility of a strike 
resulting in serious injury or mortality are discountable. At average 
transit speed, the probability of serious injury or mortality resulting 
from a strike is less than 50 percent. However, the likelihood of a 
strike actually happening is again discountable. Ship strikes, as 
analyzed in the studies cited above, generally involve commercial 
shipping, which is much more common in both space and time than is 
geophysical survey activity. 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). No such incidents were reported for geophysical 
survey vessels during that time period.
    It is possible for ship strikes to occur while traveling at slow 
speeds. For example, a hydrographic survey vessel traveling at low 
speed (5.5 kn) while conducting mapping surveys off the central 
California coast struck and killed a blue whale in 2009. The State of 
California determined that the whale had suddenly and unexpectedly 
surfaced beneath the hull, with the result that the propeller severed 
the whale's vertebrae, and that this was an unavoidable event. This 
strike represents the only such incident in approximately 540,000 hours 
of similar coastal mapping activity (p = 1.9 x 10-\6\; 95 
percent CI = 0-5.5 x 10-\6\; NMFS, 2013b). In addition, a 
research vessel reported a fatal strike in 2011 of a dolphin in the 
Atlantic, demonstrating that it is possible for strikes involving 
smaller cetaceans to occur. In that case, the incident report indicated 
that an animal apparently was struck by the vessel's propeller as it 
was intentionally swimming near the vessel. While indicative of the 
type of unusual events that cannot be ruled out, neither of these 
instances represents a circumstance that would be considered reasonably 
foreseeable or that would be considered preventable.

[[Page 14222]]

    Although the likelihood of the vessel striking a marine mammal is 
low, we require a robust ship strike avoidance protocol (see Proposed 
Mitigation), which we believe eliminates any foreseeable risk of ship 
strike. We anticipate that vessel collisions involving a seismic data 
acquisition vessel towing gear, while not impossible, represent 
unlikely, unpredictable events for which there are no preventive 
measures. Given the required mitigation measures, the relatively slow 
speed of the vessel towing gear, the presence of bridge crew watching 
for obstacles at all times (including marine mammals), and the presence 
of marine mammal observers, 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, and this potential effect of the specified activity will 
not be discussed further in the following analysis.
    Stranding--When a living or dead marine mammal swims or floats onto 
shore and becomes ``beached'' or incapable of returning to sea, the 
event is a ``stranding'' (Geraci et al., 1999; Perrin and Geraci, 2002; 
Geraci and Lounsbury, 2005; NMFS, 2007). The legal definition for a 
stranding under the MMPA is that (A) a marine mammal is dead and is (i) 
on a beach or shore of the United States; or (ii) in waters under the 
jurisdiction of the United States (including any navigable waters); or 
(B) a marine mammal is alive and is (i) on a beach or shore of the 
United States and is unable to return to the water; (ii) on a beach or 
shore of the United States and, although able to return to the water, 
is in need of apparent medical attention; or (iii) in the waters under 
the jurisdiction of the United States (including any navigable waters), 
but is unable to return to its natural habitat under its own power or 
without assistance.
    Marine mammals strand for a variety of reasons, such as infectious 
agents, biotoxicosis, starvation, fishery interaction, ship strike, 
unusual oceanographic or weather events, sound exposure, or 
combinations of these stressors sustained concurrently or in series. 
However, the cause or causes of most strandings are unknown (Geraci et 
al., 1976; Eaton, 1979; Odell et al., 1980; Best, 1982). Numerous 
studies suggest that the physiology, behavior, habitat relationships, 
age, or condition of cetaceans may cause them to strand or might pre-
dispose them to strand when exposed to another phenomenon. These 
suggestions are consistent with the conclusions of numerous other 
studies that have demonstrated that combinations of dissimilar 
stressors commonly combine to kill an animal or dramatically reduce its 
fitness, even though one exposure without the other does not produce 
the same result (Chroussos, 2000; Creel, 2005; DeVries et al., 2003; 
Fair and Becker, 2000; Foley et al., 2001; Moberg, 2000; Relyea, 2005a; 
2005b, Romero, 2004; Sih et al., 2004).
    Use of military tactical sonar has been implicated in a majority of 
investigated stranding events. Most known stranding events have 
involved beaked whales, though a small number have involved deep-diving 
delphinids or sperm whales (e.g., Mazzariol et al., 2010; Southall et 
al., 2013). In general, long duration (~1 second) and high-intensity 
sounds (>235 dB SPL) have been implicated in stranding events 
(Hildebrand, 2004). With regard to beaked whales, mid-frequency sound 
is typically implicated (when causation can be determined) (Hildebrand, 
2004). Although seismic airguns create predominantly low-frequency 
energy, the signal does include a mid-frequency component. We have 
considered the potential for the proposed surveys to result in marine 
mammal stranding and have concluded that, based on the best available 
information, stranding is not expected to occur.
    Effects to Prey--Marine mammal prey varies by species, season, and 
location and, for some, is not well documented. Fish react to sounds 
which are especially strong and/or intermittent low-frequency sounds. 
Short duration, sharp sounds can cause overt or subtle changes in fish 
behavior and local distribution. Hastings and Popper (2005) identified 
several studies that suggest fish may relocate to avoid certain areas 
of sound energy. Additional studies have documented effects of pulsed 
sound on fish, although several are based on studies in support of 
construction projects (e.g., Scholik and Yan, 2001, 2002; Popper and 
Hastings, 2009). Sound pulses at received levels of 160 dB may cause 
subtle changes in fish behavior. SPLs of 180 dB may cause noticeable 
changes in behavior (Pearson et al., 1992; Skalski et al., 1992). SPLs 
of sufficient strength have been known to cause injury to fish and fish 
mortality. The most likely impact to fish from survey activities at the 
project area would be temporary avoidance of the area. 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 
anticipated.
    Information on seismic airgun impacts to zooplankton, which 
represent an important prey type for mysticetes, is limited. However, 
McCauley et al. (2017) reported that experimental exposure to a pulse 
from a 150 inch\3\ airgun decreased zooplankton abundance when compared 
with controls, as measured by sonar and net tows, and caused a two- to 
threefold increase in dead adult and larval zooplankton. Although no 
adult krill were present, the study found that all larval krill were 
killed after air gun passage. Impacts were observed out to the maximum 
1.2 km range sampled.
    In general, impacts to marine mammal prey are expected to be 
limited due to the relatively small temporal and spatial overlap 
between the proposed survey and any areas used by marine mammal prey 
species. The proposed use of airguns as part of an active seismic array 
survey would occur over a relatively short time period (~18 days) and 
would occur over a very small area relative to the area available as 
marine mammal habitat in the Gulf of Alaska. We believe any impacts to 
marine mammals due to adverse affects to their prey would be 
insignificant due to the limited spatial and temporal impact of the 
proposed survey. However, adverse impacts may occur to a few species of 
fish and to zooplankton.
    Acoustic Habitat--Acoustic habitat is the soundscape--which 
encompasses all of the sound present in a particular location and time, 
as a whole--when considered from the perspective of the animals 
experiencing it. Animals produce sound for, or listen for sounds 
produced by, conspecifics (communication during feeding, mating, and 
other social activities), other animals (finding prey or avoiding 
predators), and the physical environment (finding suitable habitats, 
navigating). Together, sounds made by animals and the geophysical 
environment (e.g., produced by earthquakes, lightning, wind, rain, 
waves) make up the natural contributions to the total acoustics of a 
place. These acoustic conditions, termed acoustic habitat, are one 
attribute of an animal's total habitat.
    Soundscapes are also defined by, and acoustic habitat influenced 
by, the total contribution of anthropogenic sound. This may include 
incidental emissions from sources such as vessel traffic, or may be 
intentionally introduced to the marine environment for data acquisition 
purposes (as in the use of airgun arrays). Anthropogenic noise varies 
widely in its frequency content, duration, and loudness and these 
characteristics greatly influence the potential habitat-

[[Page 14223]]

mediated effects to marine mammals (please see also the previous 
discussion on masking under ``Acoustic Effects''), which may range from 
local effects for brief periods of time to chronic effects over large 
areas and for long durations. Depending on the extent of effects to 
habitat, animals may alter their communications signals (thereby 
potentially expending additional energy) or miss acoustic cues (either 
conspecific or adventitious). For more detail on these concepts see, 
e.g., Barber et al., 2010; Pijanowski et al., 2011; Francis and Barber, 
2013; Lillis et al., 2014.
    Problems arising from a failure to detect cues are more likely to 
occur when noise stimuli are chronic and overlap with biologically 
relevant cues used for communication, orientation, and predator/prey 
detection (Francis and Barber, 2013). Although the signals emitted by 
seismic airgun arrays are generally low frequency, they would also 
likely be of short duration and transient in any given area due to the 
nature of these surveys. As described previously, exploratory surveys 
such as this one cover a large area but would be transient rather than 
focused in a given location over time and therefore would not be 
considered chronic in any given location.
    In summary, activities associated with the proposed action are not 
likely to have a permanent, adverse effect on any fish habitat or 
populations of fish species or on the quality of acoustic habitat. 
Thus, any impacts to marine mammal habitat are not expected to cause 
significant or long-term consequences for individual marine mammals or 
their populations.

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 the acoustic source (i.e., seismic airguns) has the potential to 
result in disruption of behavioral patterns for individual marine 
mammals. There is also some potential for auditory injury (Level A 
harassment) to result, primarily for high frequency species because 
predicted auditory injury zones are larger than for low-frequency 
species, mid-frequency species, phocids, and otariids. However as a 
precaution, small numbers of takes by Level A harassment are proposed 
for authorization for all species listed in Table 1 as likely to occur 
in the proposed survey area. This auditory injury is expected to be, at 
most, low level PTS and the proposed mitigation and monitoring measures 
are expected to further minimize the severity of such taking to the 
extent practicable.
    As described previously, no 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

    Using the best available science, NMFS has developed 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 for non-explosive sources--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). Based on what the available science indicates 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals are 
likely to be behaviorally harassed in a manner we consider Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g., 
vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms) 
for non-explosive impulsive (e.g., seismic airguns) or intermittent 
(e.g., scientific sonar) sources. L-DEO's proposed activity includes 
the use of impulsive seismic sources. Therefore, the 160 dB re 1 [mu]Pa 
(rms) criteria is applicable for analysis of level B harassment.
    Level A harassment for non-explosive sources--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 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

[[Page 14224]]



            Table 2--Thresholds Identifying the Onset of Permanent Threshold Shift in Marine Mammals
----------------------------------------------------------------------------------------------------------------
                                                                   PTS onset thresholds
             Hearing group              ------------------------------------------------------------------------
                                                 Impulsive *                        Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Lpk,flat: 219 dB;           LE,LF,24h: 199 dB.
                                          LE,LF,24h: 183 dB.
Mid-Frequency (MF) Cetaceans...........  Lpk,flat: 230 dB;           LE,MF,24h: 198 dB.
                                          LE,MF,24h: 185 dB.
High-Frequency (HF) Cetaceans..........  Lpk,flat: 202 dB;           LE,HF,24h: 173 dB.
                                          LE,HF,24h: 155 dB.
Phocid Pinnipeds (PW) (Underwater).....  Lpk,flat: 218 dB;           LE,PW,24h: 201 dB.
                                          LE,PW,24h: 185 dB.
Otariid Pinnipeds (OW) (Underwater)....  Lpk,flat: 232 dB;           LE,OW,24h: 219 dB.
                                          LE,OW,24h: 203 dB.
----------------------------------------------------------------------------------------------------------------
Note: * 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]Pa2s. 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 that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    The proposed surveys would acquire data with the 36-airgun array 
with a total discharge of 6,600 in\3\ at a maximum tow depth of 12 m. 
L-DEO model results are used to determine the 160-dBrms radius for the 
36-airgun array and 40-in\3\ airgun at a 12-m tow depth in deep water 
(>1,000 m) down to a maximum water depth of 2,000 m. Received sound 
levels were predicted by L-DEO's model (Diebold et al., 2010) which 
uses ray tracing for 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). In 
addition, propagation measurements of pulses from the 36-airgun array 
at a tow depth of 6 m have been reported in deep water (~1,600 m), 
intermediate water depth on the slope (~600-1,100 m), and shallow water 
(~50 m) in the Gulf of Mexico (GoM) in 2007-2008 (Tolstoy et al. 2009; 
Diebold et al. 2010).
    For deep and intermediate-water cases, the field measurements 
cannot be used readily to derive Level A and Level B isopleths, as at 
those sites the calibration hydrophone was located at a roughly 
constant depth of 350-500 m, which may not intersect all the sound 
pressure level (SPL) isopleths at their widest point from the sea 
surface down to the maximum relevant water depth for marine mammals of 
~2,000 m. At short ranges, where the direct arrivals dominate and the 
effects of seafloor interactions are minimal, the data recorded at the 
deep and slope sites are suitable for comparison with modeled levels at 
the depth of the calibration hydrophone. At longer ranges, the 
comparison with the mitigation model--constructed from the maximum SPL 
through the entire water column at varying distances from the airgun 
array--is the most relevant.
    In deep and intermediate-water depths, comparisons at short ranges 
between sound levels for direct arrivals recorded by the calibration 
hydrophone and model results for the same array tow depth are in good 
agreement (Fig. 12 and 14 in Appendix H of the NSF-USGS, 2011). 
Consequently, isopleths falling within this domain can be predicted 
reliably by the L-DEO model, although they may be imperfectly sampled 
by measurements recorded at a single depth. At greater distances, the 
calibration data show that seafloor-reflected and sub-seafloor-
refracted arrivals dominate, whereas the direct arrivals become weak 
and/or incoherent. Aside from local topography effects, the region 
around the critical distance is where the observed levels rise closest 
to the mitigation model curve. However, the observed sound levels are 
found to fall almost entirely below the mitigation model. Thus, 
analysis of the GoM calibration measurements demonstrates that although 
simple, the L-DEO model is a robust tool for conservatively estimating 
isopleths.
    In shallow water (<100 m), the depth of the calibration hydrophone 
(18 m) used during the GoM calibration survey was appropriate to sample 
the maximum sound level in the water column, and the field measurements 
reported in Table 1 of Tolstoy et al. (2009) for the 36-airgun array at 
a tow depth of 6 m can be used to derive isopleths.
    For deep water (>1,000 m), we use the deep-water radii obtained 
from L-DEO model results down to a maximum water depth of 2,000 m. The 
radii for intermediate water depths (100-1,000 m) are derived from the 
deep-water ones by applying a correction factor (multiplication) of 
1.5, such that observed levels at very near offsets fall below the 
corrected mitigation curve (Fig. 16 in Appendix H of the NSF-USGS, 
2011).
    The shallow-water radii are obtained by scaling the empirically 
derived measurements from the GoM calibration survey to account for the 
differences in tow depth between the calibration survey (6 m) and the 
proposed survey (12 m); whereas the shallow water in the GoM may not 
exactly replicate the shallow water environment at the proposed survey 
site, it has been shown to serve as a good and very conservative proxy 
(Crone et al. 2014). A simple scaling factor is calculated from the 
ratios of the isopleths determined by the deep-water L-DEO model, which 
are essentially a measure of the energy radiated by the source array.
    Measurements have not been reported for the single 40-in\3\ airgun. 
L-DEO model results are used to determine the 160 dBrms 
radius for the 40-in\3\ airgun at a 12-m tow depth in deep water (Fig. 
A-3 in the IHA application). For intermediate-water depths, a 
correction factor of 1.5 was applied to the deep-water model results. 
For shallow water, a scaling of the field measurements obtained for the 
36-airgun array was used.
    L-DEO's modeling methodology is described in greater detail in the 
IHA application. The estimated distances to the Level B harassment 
isopleth for the

[[Page 14225]]

Langseth's 36-airgun array and single 40-in\3\ airgun are shown in 
Table 3.

   Table 3--Predicted Radial Distances From R/V Langseth Seismic Source to Isopleths Corresponding to Level B
                                              Harassment Threshold
----------------------------------------------------------------------------------------------------------------
                                                                                         Predicted distances (in
                   Source and volume                      Tow depth (m)    Water depth       m) to the 160-dB
                                                                               (m)         received sound level
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun, 40 in\3\...........................              12          >1,000                  \1\ 431
                                                                              100-1,000                  \2\ 647
                                                                                   <100                \3\ 1,041
4 strings, 36 airguns, 6,600 in\3\.....................              12          >1,000                \1\ 6,733
                                                                              100-1,000               \2\ 10,100
                                                                                   <100               \3\ 25,494
----------------------------------------------------------------------------------------------------------------
\1\ Distance is based on L-DEO model results.
\2\ Distance is based on L-DEO model results with a 1.5 x correction factor between deep and intermediate water
  depths.
\3\ Distance is based on empirically derived measurements in the GoM with scaling applied to account for
  differences in tow depth.

    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 software program and the 
NMFS User Spreadsheet, described below. The updated 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 2016a). 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 array were derived from calculating the modified farfield 
signature (Table 4). 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 Level B harassment 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. For a more complete explanation of this modeling approach, 
please see ``Appendix A: Determination of Mitigation Zones'' in the IHA 
application.

      Table 4--Modeled Source Levels Based on Modified Farfield Signature for the R/V Langseth 6,600 in\3\ Airgun Array, and Single 40 in\3\ Airgun
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Low frequency      Mid frequency      High frequency    Phocid Pinnipeds  Otariid Pinnipeds
                                                               cetaceans          cetaceans          cetaceans         (underwater)       (underwater)
                                                             (Lpk,flat: 219     (Lpk,flat: 230     (Lpk,flat: 202     (Lpk,flat: 218     (Lpk,flat: 232
                                                             dB; LE,LF,24h:     dB; LE,MF,24h:     dB; LE,HF,24h:     dB; LE,HF,24h:     dB; LE,HF,24h:
                                                                183 dB)            185 dB)            155 dB)            185 dB)           27462 dB)
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
6,600 in\3\ airgun array (Peak SPLflat)..................             252.06             252.65             253.24             252.25             252.52
6,600 in\3\ airgun array (SELcum)........................             232.98             232.84             233.10             232.84             232.08
40 in\3\ airgun (Peak SPLflat)...........................             223.93               N.A.             223.92             223.95               N.A.
40 in\3\ airgun (SELcum).................................             202.99             202.89             204.37             202.89             202.35
--------------------------------------------------------------------------------------------------------------------------------------------------------

    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

[[Page 14226]]

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 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 source velocities 
and shot intervals provided in the IHA application, potential radial 
distances to auditory injury zones were then calculated for 
SELcum thresholds.
    Inputs to the User Spreadsheets in the form of estimated SLs are 
shown in Table 4. User Spreadsheets used by L-DEO to estimate distances 
to Level A harassment isopleths for the 36-airgun array and single 40 
in\3\ airgun for the surveys are shown is Tables A-2, A-3, A-5, and A-8 
in Appendix A of the IHA application. Outputs from the User 
Spreadsheets in the form of estimated distances to Level A harassment 
isopleths for the surveys 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
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Low frequency      Mid frequency      High frequency    Phocid Pinnipeds  Otariid Pinnipeds
                                                               cetaceans          cetaceans          cetaceans         (underwater)       (underwater)
                                                             (Lpk,flat: 219     (Lpk,flat: 230     (Lpk,flat: 202     (Lpk,flat: 218     (Lpk,flat: 232
                                                             dB; LE,LF,24h:    dB); LE,MF,24h:    dB); LE,HF,24h:    dB); LE,HF,24h:    dB); LE,HF,24h:
                                                                183 dB)            185 dB)            155 dB)            185 dB)            203 dB)
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
6,600 in\3\ airgun array (Peak SPLflat)..................               38.9               13.6              268.3               43.7               10.6
6,600 in\3\ airgun array (SELcum)........................               40.1               N.A.                0.1                1.3               N.A.
40 in\3\ airgun (Peak SPLflat)...........................               1.76               N.A.               12.5               1.98               N.A.
40 in\3\ airgun (SELcum).................................               2.38               N.A.               N.A.               N.A.               N.A.
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used, isopleths produced may be overestimates to some degree, 
which will ultimately result in some degree of overestimate 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.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations.
    In the proposed survey area in the Gulf of Alaska, L-DEO determined 
the best marine mammal density data to be habitat-based stratified 
marine mammal densities developed by the U.S. Navy for assessing 
potential impacts of training activities in the GOA (DoN 2014). 
Alternative density estimates available for species in this region are 
not stratified by water depth and therefore do not reflect the known 
variability in species distribution relative to habitat features. 
Consistent with Rone et al. (2014), four strata were defined: 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. Densities corresponding to these strata were based on 
data from several different sources, including Navy funded line-
transect surveys in the GOA as described below and in Appendix B.
    To develop densities specific to the GOA, the Navy conducted two 
comprehensive marine mammal surveys in the Temporary Marine Activities 
Area (TMAA) in the GOA prior to 2014. The first survey was conducted 
from 10 to 20 April 2009 and the second was from 23 June to 18 July 
2013. Both surveys used systematic line-transect survey protocols 
including visual and acoustic detection methods (Rone et al. 2010; Rone 
et al. 2014). The data were collected in four strata that were designed 
to encompass the four distinct habitats within the TMAA and greater 
GOA. Rone et al. (2014) provided stratified line-transect density 
estimates used in this analysis for fin, humpback, blue, sperm, and 
killer whales, as well as northern fur seals (Table 6). Data from a 
subsequent survey in 2015 were used to calculate alternative density 
estimates for several species (Rone et al. 2017) and the density 
estimates for Dall's porpoise used here were taken from that source.
    DoN (2014) derived gray whale densities in two zones, nearshore (0-
2.25 n.mi from shore) and offshore (from 2.25-20 nmi from shore). In 
our calculations, the nearshore density was used to represent the 
inshore zone and the offshore density was used to represent the slope 
zone.
    Harbor porpoise densities in DoN (2014) were derived from Hobbs and 
Waite (2010) which included additional shallow water depth strata. The 
density estimate from the 100 m to 200 m depth strata was used to 
represent the entire inshore zone (<1,000 m) in this analysis.
    Harbor seals typically remain close to shore so minimal estimates 
were used for the three deep water zones. To account for increased 
inshore density, a one thousand fold increase of the minimal density 
was assumed to represent the entire inshore zone (DoN 2014).
    Densities for Minke whale, Pacific white-sided dolpin, and Cuvier's 
and Baird's beaked whales were based on Waite (2003 in DoN 2009). 
Although sei whale sightings and Stejneger's beaked whale acoustic 
detections were recorded during the Navy funded GOA surveys, data were 
insufficient to calculate densities for these species, so predictions 
from a global model of marine mammals densities were used (DoN 2014).
    Steller sea lion and northern elephant seal densities were 
calculated using shore-based population estimates divided by the area 
of the GOA Large Marine Ecosystem (DoN 2014).
    The North Pacific right whale, Risso's dolphin, and California sea 
lion are only rarely observed in or near the survey area, so minimal 
densities were used to represent their potential presence.

[[Page 14227]]

However, in the North Pacific right whale critical habitat off of 
Kodiak Island, it is reasonable to expect a higher density. In this 
critical habitat area, the Alaska Fisheries Science Center (LOA 
application available here: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities) used a conservative density estimate based on 
acoustic detections (Rone et al. 2014) and photo identifications 
throughout the entirety of the Gulf of Alaska. For the portion of L-
DEO's activities that occur in North Pacific right whale critical 
habitat, NMFS will use this more conservative density estimate (Table 
6).
    All densities were corrected for perception bias [f(0)] but only 
harbor porpoise densities were corrected for availability bias [g(0)], 
as described by the respective authors. There is some uncertainty 
related to the estimated density data and the assumptions used in their 
calculations, as with all density data estimates. However, the approach 
used here is based on the best available data and are stratified by the 
water depth (habitat) zones present within the survey area. These depth 
stratified densities allow L-DEO to better capture known variability in 
species distribution in the Gulf of Alaska, and accurately assess 
impacts. Alternative density estimates were available for species in 
this region, such as those used by the Alaska Fisheries Science Center 
(AFSC) (AFSC LOA application available here: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities). AFSC density values 
were not stratified by water depth and represented marine mammal 
density throughout the entire Gulf of Alaska. While some density 
estimates provided in the AFSC application are more conservative, the 
relative proximity of surveys that generated DoN estimates and L-DEO's 
consideration and inclusion of publically available newer values from 
Rone et al. (2017) mean the calculated exposures that are based on 
these densities are best estimates for L-DEO's proposed survey.

                  Table 6--Marine Mammal Density Values in the Proposed Survey Area and Source
----------------------------------------------------------------------------------------------------------------
                                              Estimated density  (#/1,000 km \2\)
                               ----------------------------------------------------------------
                                                                   Offshore      Seamount (in
          Species \1\               Inshore     Slope (1,000 m   (offshore of       defined          Source
                                  (<1,000 m)      to Aleutian      Aleutian        seamount
                                                    trench)         trench)         areas)
----------------------------------------------------------------------------------------------------------------
LF Cetaceans:
    North Pacific Right Whale.     \2\ 0.00001     \2\ 0.00001     \2\ 0.00001     \2\ 0.00001  DoN (2014).
    Humpback Whale............           0.129          0.0002           0.001           0.001  Rone et al.
                                                                                                 (2014) (Table
                                                                                                 16).
    Blue whale................          0.0005          0.0005          0.0005           0.002  Rone et al.
                                                                                                 (2014) (Table
                                                                                                 16).
    Fin Whale.................           0.071           0.014           0.021           0.005  Rone et al.
                                                                                                 (2014) (Table
                                                                                                 16).
    Sei Whale.................          0.0001          0.0001          0.0001          0.0001  DoN (2014),
                                                                                                 adapted from
                                                                                                 Figure 5-24.
    Minke Whale...............          0.0006          0.0006          0.0006          0.0006  DoN (2014).
    Gray Whale................     \3\ 0.04857     \3\ 0.00243           \3\ 0           \3\ 0  DoN (2014)
MF Cetaceans:
    Sperm Whale...............               0          0.0033          0.0013         0.00036  DoN (2014).
    Killer Whale..............           0.005            0.02           0.002           0.002  Rone et al.
                                                                                                 (2014) (Table
                                                                                                 14).
    Pacific White-Sided                 0.0208          0.0208          0.0208          0.0208  DoN (2014).
     Dolphin.
    Cuvier's Beaked Whale.....          0.0022          0.0022          0.0022          0.0022  Waite (2003) in
                                                                                                 DoN (2014)
    Baird's Beaked Whale......          0.0005          0.0005          0.0005          0.0005  DoN (2014).
    Stejneger's Beaked Whale..     \4\ 0.00001         0.00142         0.00142         0.00142  DoN (2014),
                                                                                                 adapted from
                                                                                                 Figure 9-12.
    Risso's Dolphin...........         0.00001         0.00001         0.00001         0.00001  DoN (2014).
HF Cetaceans:
    Harbor Porpoise...........          0.0473               0               0               0  Hobbes and Waite
                                                                                                 (2010) in DoN
                                                                                                 (2014).
    Dall's Porpoise...........           0.218           0.196           0.037           0.024  Rone et al.
                                                                                                 (2017).
Otarrid Seals:
    Steller Sea Lion..........          0.0098          0.0098          0.0098          0.0098  DoN (2014).
    California Sea Lion.......         0.00001         0.00001         0.00001         0.00001  DoN (2014).
    Northern Fur Seal.........           0.015           0.004           0.017           0.006  Rone et al.
                                                                                                 (2014) (Table
                                                                                                 14).
Phocid Seals:
    Northern Elephant Seal....          0.0022          0.0022          0.0022           0.022  DoN (2014).
    Harbor Seal...............            0.01         0.00001         0.00001         0.00001  DoN (2014).
----------------------------------------------------------------------------------------------------------------
\1\ No stock specific densities are available so densities are assumed equal for all stocks present.
\2\ For North Pacific right whales, estimated density within the Kodiak Island critical habitat is 0.0053
  animals/km\2\, based on detections from the GOALSII survey (Rone et al. 2014), the assumed use of the critical
  habitat by all right whales in the Gulf of Alaska (Wade et al. 2011a), and a conservative correction factor.
\3\ Gray whale density was defined in two zones, nearshore (0-2.25 n.mi from shore) and offshore (from 2.25-20
  nmi from shore). In our calculations, the nearshore density was used to represent the inshore zone and the
  offshore density was used to represent the slope zone. In areas further offshore than the slope, density was
  assumed to be 0.
\4\ Stejneger's whale are generally found in slope waters, therefore, assuming minimal inshore density.

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 harassment or Level B harassment, radial 
distances from the airgun array to predicted isopleths corresponding to 
the Level A harassment and Level B

[[Page 14228]]

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 harassment and Level B harassment thresholds. The area estimated to 
be ensonified in a single day of the survey is then calculated (Table 
7), based on the areas predicted to be ensonified around the array and 
the estimated trackline distance traveled per day. This number is then 
multiplied by the number of survey days. Active seismic operations are 
planned for 18 days during this Gulf of Alaska survey.

            Table 7--Areas (km\2\) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds, per Day for Gulf of Alaska Survey
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               Daily                                           Total
                                                           Criteria (dB)    ensonified     Total survey     25 percent      ensonified       Relevant
                                                                             area (km)         days          increase        area (km)     isopleth (m)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Level B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inshore \1\.............................................             160         19,63.1              18            1.25        44,170.3          10,100
Slope...................................................             160           684.1              18            1.25        15,392.8           6,733
Offshore................................................             160         1,159.5              18            1.25        26,087.8           6,733
Seamount................................................             160          1,19.8              18            1.25         2,695.2           6,733
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         Level A
--------------------------------------------------------------------------------------------------------------------------------------------------------
LF Cetacean.............................................  ..............            19.6              18            1.25           441.1            40.1
MF Cetacean.............................................  ..............             6.6              18            1.25           149.6            13.6
HF Cetacean.............................................  ..............           131.1              18            1.25         2,950.8           268.3
Otarid..................................................  ..............             5.2              18            1.25           116.6            10.6
Phocid..................................................  ..............            21.4              18            1.25           480.6            43.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Includes area ensonified above 160 dB in waters <100 m deep using an isopleth distance of 25,493 m. See application for further explanation.

    The product is then multiplied by 1.25 to account for the 
additional 25 percent contingency. This results in an estimate of the 
total areas (km\2\) expected to be ensonified to the Level A harassment 
and Level B harassment thresholds. The marine mammals predicted to 
occur within these respective areas, based on estimated densities, are 
assumed to be incidentally taken. Estimated exposures for the Gulf of 
Alaska seismic survey are shown in Table 8.

 Table 8--Estimated Level A and Level B Exposures, and Percentage of Stock or Population Exposed During Gulf of
                                                  Alaska Survey
----------------------------------------------------------------------------------------------------------------
                                                                                                   Percentage of
                                      Stock         Level B \1\     Level A \1\     Stock size         stock
----------------------------------------------------------------------------------------------------------------
LF Cetaceans:
    North Pacific Right Whale.  Eastern North             \2\ 11               0              31           (\3\)
                                 Pacific.
    Humpback Whale............  Central North          \4\ 5,101           \5\ 1          11,398           (\3\)
                                 Pacific (Hawaii
                                 DPS) \3\.
                                Central North            \4\ 602                           3,264           18.44
                                 Pacific (Mexico
                                 DPS) \3\.
                                Western North             \4\ 29                           1,107            2.62
                                 Pacific \3\.
    Blue whale................  Eastern North                 48           \5\ 1           1,647            2.98
                                 Pacific.
                                Central North                                                133           (\3\)
                                 Pacific.
    Fin Whale.................  Northeast                  3,912               1       \6\ 3,168           (\3\)
                                 Pacific.
    Sei Whale.................  Eastern North                  8               1             519            1.73
                                 Pacific.
    Minke Whale...............  Alaska..........              53               1       \7\ 1,233            4.38
    Gray Whale................  Eastern North              2,182           \5\ 1          26,960            8.10
                                 Pacific.
                                Western North                                                175           (\3\)
                                 Pacific.
MF Cetaceans:
    Sperm Whale...............  North Pacific...              85               1         \8\ 345           24.93
    Killer Whale..............  Alaska Resident.             586           \5\ 1           2,347           25.01
                                Gulf of Alaska,                                              587           (\3\)
                                 Aleutian
                                 Islands, and
                                 Bering Sea
                                 Transient.
                                Offshore........                                             240           (\3\)
    Pacific White-Sided         North Pacific...           1,837               1          26,880            6.84
     Dolphin.
    Cuvier's Beaked Whale.....  Alaska..........             194               1          \9\ NA              NA
    Baird's Beaked Whale......  Alaska..........              44               1          \9\ NA              NA
    Stejneger's Beaked Whale..  Alaska..........              63               1          \9\ NA              NA
    Risso's Dolphin...........  CA/OR/WA........         \10\ 16               1           6,336            0.27
HF Cetaceans:
    Harbor Porpoise...........  Gulf of Alaska..      \11\ 1,879           \5\ 3          31,046       \11\ 6.06
                                Southeast Alaska        \11\ 209                             975      \11\ 21.74
    Dall's Porpoise...........  Alaska..........          13,656              21          83,400           16.44
Otarrid Seals:
    Steller Sea Lion..........  Eastern U.S.....             865           \5\ 1          41,638            2.08

[[Page 14229]]

 
                                Western U.S.....                                          54,267            1.60
    California Sea Lion.......  U.S.............          \12\ 1               1         296,750         0.00067
    Northern Fur Seal.........  Eastern Pacific.           1,183               1         620,660            0.19
Phocid Seals:
    Northern Elephant Seal....  California                   194               1         179,000            0.11
                                 Breeding.
    Harbor Seal...............  South Kodiak....             442           \5\ 1          19,199            2.31
                                Cook Inlet/                                               27,386            1.62
                                 Shelikof Strait.
                                Prince William                                            29,889            1.48
                                 Sound.
----------------------------------------------------------------------------------------------------------------
\1\ Conservatively where less than 1 take by Level A harassment was calculated, we are rounding up to propose
  authorizing 1 take by Level A harassment. Therefore, unless otherwise noted, all calculated takes by Level B
  harassment have been reduced by the number of authorized takes by Level A harassment. This prevents double
  counting of takes across the two levels of harassment.
\2\ NMFS feels that take by Level A harassment of North Pacific right whale can be effectively avoided based on
  mitigation and monitoring measures, and therefore has not proposed to authorize a take by Level A harassment
  for the species.
\3\ The percentage of these stocks expected to experience take is discussed further in the Small Numbers section
  later in the document.
\4\ Takes are allocated amongst the three DPSs in the area based on Wade et al. 2016 (0.5% WNP, 89.0% Hawaii
  DPS, 10.5% Mexico DPS). Because of rounding, the total take is higher than calculated. Population sizes for
  the Hawaii and Mexican DPSs are provided in 81 FR 62259 (effective October 11, 2016).
\5\ Where multiple stocks are being affected, for the purposes of calculating the percentage of the stock
  impacted, the single Level A take is being analyzed as if it occurred within each stock.
\6\ Fin whale abundance estimate is the highest of Rone et al. (2017) estimates. Based on the limited footprint
  of the surveys that lead to this estimate, the true abundance of the stock is expected to be much higher.
\7\ Minke whale abundance estimates is from Zerbini et al. (2006).
\8\ Sperm whale abundance estimates is the maximum value from Rone et al. (2017).
\9\ For beaked whales, there is no accepted estimates of abundance for the Alaska stocks.
\10\ The requested number of takes by Level B harassment for Risso's dolphin has been increased to 16, the
  average group size. Because this is a qualitative estimate, this take request has not been reduced by 1 to
  facilitate the requested take by Level A harassment.
\11\ Based on the range of the Southeast Alaska stock of harbor porpoises, they are expected to be very rare in
  the area (See ``Description of Marine Mammals in the Area of Specified Activities''). We therefore
  conservatively assume that at most, 10 percent of takes will occur from the Southeast Alaska population. The
  numbers for both Gulf of Alaska and Southeast Alaska stocks reflect this assumption. Because of rounding, the
  total take between the two stocks is higher than the original calculation.
\12\ Only 1 take by Level B harassment was requested for California sea lion, but a take by Level A harassment
  was also requested. Therefore, the amount of take by Level B harassment has not be reduced by the proposed
  numbers of take by Level A harassment.

    It should be noted that the proposed take numbers shown in Table 8 
are expected to be conservative for several reasons. First, in the 
calculations of estimated take, 25 percent has been added in the form 
of operational survey days to account for the possibility of additional 
seismic operations associated with airgun testing and repeat coverage 
of any areas where initial data quality is sub-standard, and in 
recognition of the uncertainties in the density estimates used to 
estimate take as described above. Additionally, marine mammals would be 
expected to move away from a loud sound source that represents an 
aversive stimulus, such as an airgun array, potentially reducing the 
number of takes by Level A harassment. However, the extent to which 
marine mammals would move away from the sound source is difficult to 
quantify and is, therefore, not accounted for in the take estimates.
    Note that for North Pacific right whales and Risso's dolphin, we 
propose to authorize a different number of incidental takes than the 
number of incidental takes requested by L-DEO (see Table 6 in the IHA 
application for requested take numbers). For Risso's dolphin, we 
proposed to authorize take by Level B harassment of an average sized 
group, 16 individuals, instead of the single individual requested by L-
DEO. Our rational for North Pacific right whale take is described 
below.
    For North Pacific right whale, there is evidence of a much higher 
density in the critical habitat south of Kodiak Island (Table 6). This 
density value of 0.0053 animals/km\2\ is based on detections from the 
GOALSII survey (4 individuals) (Rone et al. 2014), the assumed use of 
the critical habitat by all right whales in the Gulf of Alaska (Wade et 
al 2011a), and a conservative correction factor (4), all divided by the 
area of the critical habitat (3,042.2 km\2\). To account for this 
habitat, NMFS used the Alaska Protected Resources Division Species 
Distribution Mapper (https://www.fisheries.noaa.gov/resource/data/alaska-endangered-species-and-critical-habitat-mapper-web-application) 
to determine a conservative approximation of L-DEO's survey path 
through the critical habitat based on the representative tracks in 
Figure 1 of the IHA Application. This measured distance was 35 km. 
Because the majority of this habitat is inside of the 100 m isopleth, 
the predicted distance to the 160-dB received sound level would be 
~25.5 km. This resulted in a portion of the critical habitat 35 km long 
by 51 km wide (25.5 km on each side of the survey track), or 1,785 
km\2\ being ensonified. Applying the higher density of 0.0053 animals/
km\2\ to this area, results in an estimate of 9.46 North Pacific right 
whales exposed to Level B harassment in the critical habitat. No 
further correction, such as the 25 percent operation day increase, is 
needed for the estimate in the critical habitat, because the density of 
0.0053 animals/km\2\ has already been corrected to be highly 
conservative (AFSC Application, Table 6-10d). To account for the rest 
of the survey occurring outside of the critical habitat, the minimal 
density presented in DoN (2014), 0.00001 individuals/km\2\, was used 
for the remainder of the survey. The expected take in the rest of the 
survey is 1.10 individuals. Summing these two estimates for take, in 
both the critical habitat and remainder of survey, results in an 
expected take of 10.56 individuals (rounded to 11 individuals). With 
other species one calculated take was conservatively assumed to be a 
take by Level A harassment (Table 8), however no takes by Level A 
harassment are proposed for authorization for North Pacific right whale 
given the low density of the species and NMFS evaluation of the 
effectiveness of mitigation and monitoring measures.

[[Page 14230]]

Effects of Specified Activities on Subsistence Uses of Marine Mammals

    The availability of the affected marine mammal stocks or species 
for subsistence uses may be impacted by this activity. The subsistence 
uses that may be affected and the potential impacts of the activity on 
those uses are described below. Measures included in this IHA to reduce 
the impacts of the activity on subsistence uses are described in the 
Proposed Mitigation section. Last, the information from this section 
and the Proposed Mitigation section is analyzed to determine whether 
the necessary findings may be made in the Unmitigable Adverse Impact 
Analysis and Determination section.
    In the GOA, the marine mammals that are hunted are Steller sea 
lions and harbor seals. In 2011-2012, 37 harbor seals were taken from 
the North Kodiak Stock and 126 harbor seals were taken from the South 
Kodiak Stock by communities on Kodiak Island (Muto et al. 2016). The 
number taken from the Cook Inlet/Shelikof Strait Stock for 2011-2012 is 
unknown, but an average of 233 were taken from this stock annually 
during 2004-2008 (Muto et al. 2016). The seasonal distribution of 
harbor seal takes by Alaska Natives typically shows two distinct 
hunting peaks--one during spring and one during fall and early winter; 
however, seals are taken in all months (Wolfe et al. 2012). In general, 
the months of highest harvest are September through December, with a 
smaller peak in February/March (Wolfe et al. 2012). Harvests are 
traditionally low from May through August, when harbor seals are 
raising pups and molting.
    In 2008, 19 Steller sea lions were taken in the Kodiak Island 
region and 9 were taken along the South Alaska Peninsula (Wolfe et al. 
2009). As of 2009, data on community subsistence harvests are no longer 
being collected consistently so few data are available. Wolfe et al. 
(2012) reported an estimated 20 sea lions taken by hunters on Kodiak 
Island in 2011. The most recent 5-year period with data available 
(2004-2008) shows an annual average catch of 172 steller sea lions for 
all areas in Alaska combined except the Pribilof Islands in the Bering 
Sea (Muto et al. 2018). Sea lions are taken from Kodiak Island in low 
numbers year round (Wolfe et al. 2012).
    The proposed project could potentially impact the availability of 
marine mammals for harvest in a small area immediately around the 
Langseth, and for a very short time period during seismic operations. 
Considering the limited time that the planned seismic surveys would 
take place close to shore, where most subsistence harvest of marine 
mammals occurs in the Gulf of Alaska, the proposed project is not 
expected to have any significant impacts to the availability of Steller 
sea lions or harbor seals for subsistence harvest. Additionally, to 
mitigate any possible conflict, community outreach is planned and 
described further in ``Proposed Mitigation'' below.

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 such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for certain 
subsistence uses. 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 such 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, as 
well as subsistence uses. 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.
    L-DEO has reviewed mitigation measures employed during seismic 
research surveys authorized by NMFS under previous incidental 
harassment authorizations, as well as recommended best practices in 
Richardson et al. (1995), Pierson et al. (1998), Weir and Dolman 
(2007), Nowacek et al. (2013), Wright (2014), and Wright and Cosentino 
(2015), and has incorporated a suite of proposed mitigation measures 
into their project description based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, L-DEO has proposed to implement 
mitigation measures for marine mammals. Mitigation measures that would 
be adopted during the proposed surveys include (1) Vessel-based visual 
mitigation monitoring; (2) Vessel-based passive acoustic monitoring; 
(3) Establishment of an exclusion zone; (4) Power down procedures; (5) 
Shutdown procedures; (6) Ramp-up procedures; (7) Vessel strike 
avoidance measures; and (8) Sensitive Habitat Measures.

Vessel-Based Visual Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual PSOs) to scan the ocean surface visually for the 
presence of marine mammals. The area to be scanned visually includes 
primarily the exclusion zone, but also the buffer zone. The buffer zone 
means an area beyond the exclusion zone to be monitored for the 
presence of marine mammals that may enter the exclusion zone. During 
pre-clearance monitoring (i.e., before ramp-up begins), the buffer zone 
also acts as an extension of the exclusion zone 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 
exclusion zone, out to a radius of 1,000 m from the edges of the airgun 
array (500-1,000 m). Visual monitoring of the exclusion zones 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 close 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-clearance, and (2) 
during airgun use, aid in establishing and maintaining the

[[Page 14231]]

exclusion zone by alerting the visual observer and crew of marine 
mammals that are outside of, but may approach and enter, the exclusion 
zone.
    L-DEO must use at least five dedicated, trained, NMFS-approved 
Protected Species Observers (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 aboard the 
vessel must have a minimum of 90 days at-sea experience working in 
those roles, respectively, during a deep penetration (i.e., ``high 
energy'') seismic survey, 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 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) and 30 minutes prior to and during 
nighttime ramp-ups of the airgun array. Visual monitoring of the 
exclusion and buffer zones must begin no less than 30 minutes prior to 
ramp-up and 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 airgun (i.e., anytime the acoustic source is 
active, including ramp-up), occurrences of marine mammals within the 
buffer zone (but outside the exclusion zone) shall be communicated to 
the operator to prepare for the potential shutdown or powerdown 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 four 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 exclusion zone 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.
    Passive acoustic monitoring (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. Acoustical 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 call, 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 four 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 two 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 exclusion zone in the previous two 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 four hours in 
any 24-hour period.

Establishment of an Exclusion Zone and Buffer Zone

    An exclusion zone (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 for the 36 airgun array. The 500 m EZ would be based on radial 
distance from any element 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 500 m EZ is intended to be precautionary in the sense that it 
would

[[Page 14232]]

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.
    Because the North Pacific right whale is a stock of high concern, 
L-DEO will implement a shutdown if the species is observed at any 
distance. In addition, when transiting through North Pacific right 
whale critical habitat, L-DEO must do any such transit during daylight 
hours, to facilitate the ability of PSOs to observe any right whales 
that may be present. Additionally, for high risk circumstances, such as 
observation of a calf or aggregation of whales, L-DEO will shutdown if 
these circumstances are observed at any distance.
    Finally, to minimize impact on fin whales in their feeding BIA near 
Kodiak Island, L-DEO must observe a larger EZ for this species while in 
the BIA. If a fin whale or group of fin whales is observed with 1,500 m 
of the acoustic source within the fin whale BIA, L-DEO must implement a 
shutdown.

Pre-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 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-
clearance observation (30 minutes) is to ensure no protected species 
are observed within the buffer zone prior to the beginning of ramp-up. 
During pre-clearance is the only time observations of protected species 
in the buffer zone would prevent operations (i.e., the beginning of 
ramp-up). The intent of ramp-up is to warn protected species 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-
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 exclusion and buffer zones 
for 30 minutes prior to the initiation of ramp-up (pre-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-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 applicable exclusion zone or the buffer zone during 
the 30 minute pre-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 30 minutes for all other species).
     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 exclusion and buffer zones during 
ramp-up, and ramp-up must cease and the source must be shut down upon 
observation of a marine mammal within the applicable exclusion zone. 
Once ramp-up has begun, observations of marine mammals within the 
buffer zone do not require shutdown or powerdown, but such observation 
shall be communicated to the operator to prepare for the potential 
shutdown or powerdown.
     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 and powerdown (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 exclusion zone. For 
any longer shutdown, pre-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-clearance 
watch of 30 min is not required.
     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-clearance of 30 
min.

Shutdown and Powerdown

    The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array while a 
powerdown requires immediate de-activation of all individual airgun 
elements of the array except the single 40-in\3\ airgun. Any PSO on 
duty will have the authority to delay the start of survey operations or 
to call for shutdown or powerdown of the acoustic source if a marine 
mammal is detected within the applicable exclusion zone. 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 and powerdown 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 powerdown) and (1) a 
marine mammal appears within or enters the applicable exclusion zone 
and/or (2) a marine mammal (other than delphinids, see below) is 
detected acoustically and localized within the applicable exclusion 
zone, the acoustic source will be shut down. When shutdown is called 
for by a PSO, the acoustic source will be immediately

[[Page 14233]]

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 500 m EZ. The animal would be considered 
to have cleared the 500 m EZ if it is visually observed to have 
departed the 500 m EZ, or it has not been seen within the 500 m EZ for 
15 min in the case of small odontocetes and pinnipeds, or 30 min in the 
case of mysticetes and large odontocetes, including sperm Cuvier's 
beaked, Baird's beaked, Stejneger's beaked, and killer whales.
    The shutdown requirement can be waived for small dolphins in which 
case the acoustic source shall be powered down to the single 40-in\3\ 
airgun if an individual is visually detected within the exclusion zone. 
As defined here, the small delphinoid 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 would apply solely to specific genera of small dolphins--
Lagenorhynchus and Grampus--The acoustic source shall be powered down 
to 40-in\3\ airgun if an individual belonging to these genera is 
visually detected within the 500 m exclusion zone.
    Powerdown conditions shall be maintained until delphinids for which 
shutdown is waived are no longer observed within the 500 m exclusion 
zone, following which full-power operations may be resumed without 
ramp-up. Visual PSOs may elect to waive the powerdown requirement if 
delphinids for which shutdown is waived to be voluntarily approaching 
the vessel for the purpose of interacting with the vessel or towed 
gear, and may use best professional judgment in making this decision.
    We include this small delphinid exception because power-down/
shutdown requirements for small delphinids under all circumstances 
represent practicability concerns without likely commensurate benefits 
for the animals in question. Small delphinids 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), 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 delphinids 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinids (e.g., Barkaszi et al., 2012). The potential for 
increased shutdowns resulting from such a measure would require the R/V 
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 delphinids, they are much less likely to 
approach vessels. Therefore, retaining a power-down/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 power-down/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.
    Powerdown conditions shall be maintained until the marine mammal(s) 
of the above listed genera are no longer observed within the exclusion 
zone, following which full-power operations may be resumed without 
ramp-up. Additionally, visual PSOs may elect to waive the powerdown 
requirement if the small dolphin(s) appear to be voluntarily 
approaching the vessel for the purpose of interacting with the vessel 
or towed gear, and may use best professional judgment in making this 
decision. 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 exclusion zone). If PSOs observe any behaviors in 
a small delphinid for which shutdown is waived that indicate an adverse 
reaction, then powerdown will be initiated immediately.
    Upon implementation of shutdown, the source may be reactivated 
after the marine mammal(s) has been observed exiting the applicable 
exclusion zone (i.e., animal is not required to fully exit the buffer 
zone where applicable) or following 15 minutes for small odontocetes 
and 30 minutes for all other species with no further observation of the 
marine mammal(s).

Vessel Strike Avoidance

    These measures apply to all vessels associated with the planned 
survey activity; however, we note that 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. These measures include the following:
    1. Vessel operators and crews must maintain a vigilant watch for 
all marine mammals and slow down, stop their vessel, or alter course, 
as appropriate and regardless of vessel size, to avoid striking any 
marine mammal. A single marine mammal at the surface may indicate the 
presence of submerged animals in the vicinity of the vessel; therefore, 
precautionary measures should be exercised when an animal is observed. 
A visual observer aboard the vessel must monitor a vessel strike 
avoidance zone around the vessel (specific distances detailed below), 
to ensure the potential for strike is minimized. Visual observers 
monitoring the vessel strike avoidance zone can be either third-party 
observers or crew members, but crew members responsible for these 
duties must be provided sufficient training to distinguish marine 
mammals from other phenomena and broadly to identify a marine mammal to 
broad taxonomic group (i.e., as a large whale or other marine mammal).
    2. Vessel speeds must be reduced to 10 kn or less when mother/calf 
pairs, pods, or large assemblages of any marine mammal are observed 
near a vessel.
    3. All vessels must maintain a minimum separation distance of 100 m 
from large whales (i.e., sperm whales and all baleen whales).
    4. All vessels must attempt to maintain a minimum separation 
distance of 50 m from all other marine mammals, with an exception made 
for those animals that approach the vessel.
    5. When marine mammals are sighted while a vessel is underway, the 
vessel

[[Page 14234]]

should 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 should reduce speed and shift 
the engine to neutral, not engaging the engines until animals are clear 
of the area. This recommendation does not apply to any vessel towing 
gear.
    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, NMFS has preliminarily determined that the mitigation 
measures provide the means 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.

Sensitive Habitat Measures

    Because the propose survey overlaps with BIAs and critical habitat 
for some species (see MM Occurance), L-DEO will implement additional 
measures related to these areas including area avoidance and the 
implementation of special shutdown zones. For Steller sea lion 
rookeries and major haulouts, classified as critical habitat (58 FR 
45269, August 27, 1993). Steller sea lions maintain rookeries and major 
haul-outs in the area of L-DEO's survey (Figure 1 in the IHA 
Application). Additionally the timing of the survey overlaps with the 
breeding season of Steller sea lions. As such, L-DEO must observe a 
three nautical mile exclusion zone around these critical habitats. This 
means that L-DEO avoid transiting through and operating seismic airguns 
in these areas.
    A portion of L-DEO's proposed survey will also occur in the fin 
whale BIA (Ferguson et al. 2015). Because of the temporal and spatial 
overlap in the proposed survey and peak use of the fin whale BIA, L-DEO 
will implement a shutdown if a fin whale or group of fin whales is 
observed at within a 1,500 m radius from the acoustic source, within 
their BIA. L-DEO will refer to Ferguson et al. (2015) for the location 
of the BIA, but waters around the Semidi Islands, Kodiak Island, and 
Chirikof Island generally define the portion of the BIA L-DEO is 
expected to transit through.
    The expected elevated density of North Pacific right whales in 
their critical habitat means that additional measures are prudent for 
this area. When transiting through North Pacific right whale critical 
habitat, L-DEO must do any such transit during daylight hours, to 
facilitate the ability of PSOs to observe any right whales that may be 
present. This measure is in addition to the requirement that L-DEO must 
implement a shutdown if a North Pacific right whale is observed at any 
distance.

Mitigation for Subsistence Uses of Marine Mammals--Community Outreach

    Although impacts on subsistence uses are not expected due to the 
strong separation in time and space between marine mammal subsistence 
harvest and L-DEO's proposed activities, project principle 
investigators will conduct outreach with communities near the planned 
project area to identify and avoid areas of potential conflict, 
including for marine subsistence activities. This measure will mitigate 
any potential negative impact on subsistence hunting activities, 
despite there being no expected significant impact.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means 
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, and on the 
availability of such species or stock for subsistence uses.

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 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 and nighttime start ups (if applicable) of 
the airguns. During seismic operations, at least six visual PSOs would 
be based aboard the Langseth. 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;
     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:

[[Page 14235]]

     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
     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-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);
     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.

[[Page 14236]]

    A report would be submitted to NMFS within 90 days after the end of 
the cruise. The report would describe the operations that were 
conducted and sightings of marine mammals near the operations. The 
report would provide full documentation of methods, results, and 
interpretation pertaining to all monitoring. The 90-day report would 
summarize the dates and locations of seismic operations, and all marine 
mammal sightings (dates, times, locations, activities, associated 
seismic survey activities). The report would also include estimates of 
the number and nature of exposures that occurred above the harassment 
threshold based on PSO observations, including an estimate of those on 
the trackline but not detected.

Reporting

    L-DEO will be required to shall submit a draft comprehensive report 
to NMFS on all activities and monitoring results within 90 days of the 
completion of the survey or expiration of the IHA, whichever comes 
sooner. The report must describe all activities conducted and sightings 
of protected species near the activities, must provide full 
documentation of methods, results, and interpretation pertaining to all 
monitoring, and must summarize the dates and locations of survey 
operations and all protected species sightings (dates, times, 
locations, activities, associated survey activities). The report will 
also include estimates of the number and nature of exposures that 
occurred above the harassment threshold based on PSO observations, 
including an estimate of those on the trackline but not detected. 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 
information submitted in interim monthly reports as well as additional 
data collected as described above and the IHA. The draft report must be 
accompanied by a certification from the lead PSO as to the accuracy of 
the report, and the lead PSO may submit directly NMFS a statement 
concerning implementation and effectiveness of the required mitigation 
and monitoring. A final report must be submitted within 30 days 
following resolution of any comments on the draft report.

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 
proposed seismic 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.
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of L-DEO's proposed survey, even in the absence of 
proposed mitigation. Thus the proposed authorization does not authorize 
any mortality. As discussed in the Potential Effects section, non-
auditory physical effects, stranding, and vessel strike are not 
expected to occur.
    We propose to authorize a limited number of instances of Level A 
and Level B harassment of 21 species of marine mammal species. For 19 
of these species, a single take by Level A harassment is authorized as 
a precaution. However, we believe that any PTS incurred in marine 
mammals as a result of the proposed activity would be in the form of 
only a small degree of PTS, not total deafness, and would be unlikely 
to affect the fitness of any individuals, because of the constant 
movement of both the 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 (i.e., since the duration of 
exposure to loud sounds will be relatively short). Also, as described 
above, we expect that marine mammals would be likely to 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 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 which, because of their 
comparatively short duration, are considered to be of lower severity 
and with no lasting biological consequences (e.g., Southall et al., 
2007).
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see Potential Effects of the Specified 
Activity on Marine Mammals and their Habitat). 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 
(~18 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.

[[Page 14237]]

    The tracklines of this survey either traverse or are proximal to 
the BIAs for four baleen whale species including fin, gray, North 
Pacific right, and humpback whales in U.S. waters of the Gulf of Alaska 
(Ferguson et al. 2015). Additionally, there is a BIA for beluga whales 
in nearby Cook Inlet, but the location of the BIA means the habitat 
will not co-occur with L-DEO's survey (Ferguson et al. 2015). The North 
Pacific Right whale feeding BIA east of the Kodiak Archipelago is 
primarily used between June and September. The fin whale feeding BIA 
that stretches from Kenai Peninsula through the Alaska Peninsula is 
primarily used between June and August. The gray whale feeding BIA east 
of the Kodiak Archipelago is primarily used between June and August. 
For the North Pacific Right whale, gray whale, and fin whale feeding 
BIAs, L-DEO's survey planned for June 1 through June 19, 2019 could 
overlap with a period where BIAs represent an important habitat. 
However, only of a portion of seismic survey days would actually occur 
in or near these BIAs, and all survey efforts should be completed by 
mid-June, still in the early window of primary use for all these BIAs. 
Additionally, there mitigation measures that should further reduce take 
number and severity for fin whales and North Pacific right whales. 
These include the requirement to shutdown the acoustic source if a fin 
whale, within the fin whale BIA, is observed within 1,500 meters of the 
source and the requirement to shutdown if a North Pacific right whale 
is observed at any distance from the source. The gray whale migratory 
corridor BIA and humpback whale feeding BIAs overlap spatially with L-
DEO's survey, but the timing of primary use of these BIAs does not 
overlap temporally with the survey. Gray whales are most commonly seen 
migratory northward between March and May and southward between 
November and January. As proposed, there is no possibility that L-DEO's 
survey impacts the southern migration, and presence of northern 
migrating individuals should be below peak during survey operations 
beginning in June 2019. Additionally, humpback whale feeding BIAs in 
the region are primarily used between July and August or September. L-
DEO's survey efforts should be completed before peak use of these 
feeding habitats. For all habitats, no physical impacts to BIA 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 BIAs, 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 the designated BIAs.
    Critical habitat has been designated for the ESA listed North 
Pacific right whale and western DPS of Steller sea lions. Only a 
portion of L-DEO's planned seismic survey will occur in these critical 
habitats. Steller sea lion critical habitat also includes a ``no 
approach'' zone within 3 nmi of rookeries. Steller sea lions both 
occupy rookeries and pup from late-May through early-July (NMFS 2008), 
which coincides with L-DEO's proposed survey. Thus, we are requiring 
that the proposed survey avoid transiting or surveying within 3 nmi of 
any rookeries. For North Pacific right whale critical habitat, L-DEO 
would only need to traverse approximately 35 km of the designated 
critical habitat. At a speed of approximately 9.3 km per hour (5 kn), 
L-DEO would only be in the critical habitat for less than 4 hours. L-
DEO would only traverse this critical habitat during daylight hours to 
facilitate the ability of PSOs to observe any right whales that may be 
present, so as to reduce the potential for their exposure to airgun 
noise. Additionally, L-DEO would be required to shutdown seismic 
airguns if a North Pacific right whale is observed at any distance, 
further minimizing the impacts on North Pacific right whales in their 
critical habitat and elsewhere. The characteristics that make this 
habitat an important feeding area for North Pacific right whales are 
abundant planktonic food sources. While there are possible impacts of 
seismic activity on plankton (McCauley et al., 2017), the currents that 
flow through the Gulf of Alaska will readily refresh plankton resources 
in the area. As such, this seismic activity is not expected to have a 
lasting physical impact on habitat or prey within it. Any impact would 
be a temporary increase in sound levels when the survey is occurring in 
or near the critical habitat and resulting temporary avoidance of prey 
or marine mammals themselves due these elevated sound levels.
    After accounting for qualitative factors, the activity is expected 
to impact a small percentage of all marine mammal stocks that would be 
affected by L-DEO's proposed survey (see ``Small Numbers'' below). 
Additionally, 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.
    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 power downs and/
or 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. 
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 species or stock 
through effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     The proposed activity is temporary and of relatively short 
duration (~18 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.

[[Page 14238]]

Instances of potential PTS that are incurred in marine mammals would 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;
     The proposed mitigation measures, including visual and 
acoustic monitoring, power-downs, shutdowns, and enhanced measures for 
areas of biological importance 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 monitoring and 
mitigation 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 Section 101(a)(5)(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. Additionally, other qualitative factors may 
be considered in the analysis, such as the temporal or spatial scale of 
the activities.
    There are seven stocks for which the estimated instances of take 
appear high when compared to the stock abundance (Table 8), including 
the Northeast Pacific fin whale stock, the North Pacific right whale 
stock, the Western North Pacific gray whale stock, the Central North 
Pacific blue whale stock, the Central North Pacific humpback whale 
stock (Hawaii DPS), the Offshore killer whale stock, and the Gulf of 
Alaska, Aleutian Islands, and Bering Sea transient killer whale stock. 
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 an additional three stocks (Alaska stocks of the three beaked 
whale species), there are no abundance estimates upon which to base a 
comparison. However, we note that the anticipated number of incidents 
of take by Level B and Level A harassment are low (46 to 196 for these 
three stocks) and represent a small number of animals within these 
stocks, which have extensive ranges across large parts of the North 
Pacific Ocean compared to L-DEO's proposed survey area (Muto et al, 
2018). Based on the broad spatial distributions of these species 
relative to the proposed survey area, NMFS concludes that the 
authorized take of these species represent small numbers relative to 
the affected species' overall population sizes, though we are unable to 
quantify the authorized take numbers as a percentage of population.
    For all other stocks (aside from the seven referenced above and 
described below and the three beaked whales), the authorized take is 
less than 25% as compared to the stock abundance (recognizing that some 
of those takes may be repeats of the same individual, thus rendering 
the percentage even lower).
    The expected take of the Northeast Pacific stock of fin whales 
appears to impact a high percentage of the population (123.5 percent), 
but this percentage is based on an occurrence estimate which surveyed 
only a small portion of the range (Rone et al. 2017), and no 
representative estimate of the full stock abundance is available (Muto 
et al. 2018). The range of the Northeast Pacific fin whale stock 
extends through much of the north Pacific (Muto et al. 2018). Based on 
the small portion of the stock's range that Rone et al. (2017) 
observed, the full stock abundance would be much higher than 3,168 
individuals, reducing the percentage of the population that would be 
impacted by take from L-DEO's activities. Additionally, L-DEO's actions 
are located in a small portion of the total range and will occur within 
a short period of less than a month. L-DEO's previous marine mammal 
monitoring in the Gulf of Alaska reported 79 fin whales (RPS 2011) and 
Zerbini et al. (2006) observed 530 fin whales across 3 years of summer 
surveys in the Northern Gulf of Alaska. Given these previous 
observations, it is not realistic that L-DEO will encounter 3,914 
individual fin whales. Instead, given the range of the species, the 
known underestimate of stock abundance, and the comparatively small 
action area, combined with the short duration of the survey, it is more 
likely that there will be multiple instances of take to a smaller 
number of individuals that are in the action area during the proposed 
survey and entirely unlikely that more than a third of the stock would 
be exposed to the seismic survey.
    The estimated instances of take for North Pacific right whales 
appears high compared to stock abundance (35.5 percent), but 
realistically 11 right whales are not likely to experience harassment. 
Given the higher assumed density of whales in the critical habitat area 
off of Kodiak Island, the vast majority of estimated takes would occur 
in that area (see ``Take Calculation and Estimation''). Overall, right 
whales are very rarely detected in the Gulf of Alaska, and most 
evidence of the region's importance for the species is based on 
historic whaling records (Muto et al., 2018). Either visual or acoustic 
detections of a single right whale are rare in the Gulf of Alaska. 
North Pacific right whales are much more commonly detected in their 
Bering Sea critical habitat (73 FR 19000, April 8, 2008; Muto et al., 
2018). Given this evidence, only a small portion of the population is 
expected to be present in the Gulf of Alaska and the Kodiak Island 
critical habitat. As such, it is more realistic to believe there will 
be multiple takes of the few individuals present, comprising less than 
a third of the stock. Additionally, L-DEO proposed survey will only 
impact the North Pacific right whale critical habitat for a very short 
portion of their survey and there are additional mitigation measures in 
place to further minimize any acoustic impacts on North Pacific right 
whales.
    The amount of take expected for the Western North Pacific stock 
(WNP) of gray whales appears high (1247.43 percent). In reality, 2,183 
individuals will be not experience take from this stock. There are two 
stocks of gray whales in this area, the WNP and the Eastern North 
Pacific stock (ENP). It is more realistic to apportion expected takes 
between these stocks. NMFS has no commonly used method to estimate the 
relative occurrence of these stocks, but here we propose to apportion 
the takes between the two stocks using their relative abundances and a 
correction factor to ensure this number is conservative. The total 
abundance of the two stocks is 27,135 gray whales. Based on estimates 
of stock size (Table 1), 0.65 percent of encountered gray whales would 
be expected to come from the

[[Page 14239]]

WNP stock, and 99.35 percent would be expected to come from the ENP 
stock, which results in an apportioned take estimate for each stock of 
14 (WNP) and 2,169 (ENP). To represent uncertainty in this method and 
produce a conservative estimate, we then double the apportioned take 
for the smaller stocks, resulting in an estimated 28 takes for the WNP 
stock. This estimated level of take is expected to impact an estimated 
16 percent of the WNP stock. Further supporting this conclusion, the 
summer feeding grounds of WNP gray whales are believed to be off the 
Sakhalin Islands and other parts of coastal eastern Russia. In total, 
27 to 30 whales have been observed in both the WNP and ENP, meaning 
that while some whales identified on these summer grounds have been 
observed overwintering in the eastern Pacific around North America, 
some also migrate to Japanese and Chinese waters (Caretta et al., 2014; 
Caretta et al., 2019 DRAFT). Based on relative abundance of gray whale 
stocks and knowledge of behavior, the WNP stock is expected to make up 
a small portion of the gray whales that will experience take from L-
DEO's activity. Therefore, it is entirely unlikely that more than a 
third of the stock would be exposed to the seismic survey.
    The expected instances of take of the Central North Pacific (CNP) 
stock of blue whales appears high when compared to the abundance (37 
percent), however, in reality 50 CNP blue whales are not likely to be 
harassed. Blue whales belonging to the CNP stock appear to feed in 
summer in waters southwest of Kamchatka, south of the Aleutians, and in 
the Gulf of Alaska (Stafford 2003; Watkins et al. 2000). Because of 
this large summer range of CNP blue whales compared to the size of L-
DEO's action area, it is more likely that there will be multiple takes 
of a smaller number of individuals that would occur within the action 
area, and the percentage of the stock taken will be less than a third 
of the individuals.
    For humpback whales, takes are apportioned between the different 
stocks or DPSs present based on Wade et al. (2016). With this 
apportionment, the expected instances of take of the Central North 
Pacific stock's Hawaii DPS appears high (44.8 percent of the estimated 
DPS abundance). In reality, 5101 Hawaii DPS humpback whales are not 
likely to be harassed, as it is more likely that a smaller number of 
individuals will experience multiple takes. The Gulf of Alaska is an 
important center of humpback whale abundance, and L-DEO's survey 
affects a portion of the Gulf of Alaska. The highest densities of 
humpback whales in the Gulf of Alaska are observed between July and 
August (Ferguson et al., 2015), while L-DEO's survey is planned for 
June, so the survey should not overlap with peak abundance. 
Additionally, there are other areas of high humpback whale density in 
the Aleutian Islands and Bering Sea (Muto et al. 2018). This evidence, 
plus the CNP stock's large range relative to L-DEO's action area, along 
with the short duration of the survey, mean that it is more likely that 
there will be multiple takes of a smaller portion of the individuals 
that occur in L-DEO's action area, and fewer than a third of the 
individuals in the stock will be taken.
    The expected instances of take from both the Offshore and Gulf of 
Alaska, Aleutian Islands, and Bering Sea transient stocks of killer 
whales appears high when compared against the stock abundance (245 
percent and 100.2 percent respectively). In reality, 588 individuals 
will not experience take from each of these stocks. There are three 
stocks of killer whales in this area, including the Eastern North 
Pacific Alaska Resident stock, and it is more realistic to apportion 
expected takes between these stocks. NMFS has no commonly used method 
to estimate the relative occurrence of these stocks, but here we 
propose to apportion the takes between the three stocks using their 
relative abundances and a correction factor to ensure this number is 
conservative. The total abundance of the three stocks in the area is 
3,174 killer whales. Based on estimates of stock size, 73.9 percent of 
encountered killer whales would be expected to come from the Alaska 
resident stock, 18.5 percent would be expected to come from the Gulf of 
Alaska, Aleutian Islands, and Bering Sea stock, and 7.6 percent would 
be expected to come from the offshore stock, which come to a take 
estimate for each stock of 434.8, 108.7 and 44.5 respectively. To 
represent uncertainty in this method and produce a conservative 
estimate, we then double the apportioned take for each of the smaller 
stocks, resulting in an estimated 218 takes for the Gulf of Alaska, 
Aleutian Islands, and Bering Sea stock and 90 takes for the Offshore 
stock. Carrying these estimates along results in 37.1 percent of the 
Gulf of Alaska, Aleutian Islands, and Bering Sea stock experiencing 
take and 37.5 of the Offshore stock experiencing take. While these 
numbers still appear high, the extensive ranges of both stocks compared 
to L-DEO's action area, as well as the short duration of the survey, 
mean that realistically there will be multiple takes of a smaller 
portion of both killer whale stocks, resulting in no more than a third 
of the individuals of any of these stocks being taken. Individuals from 
the offshore stock are known to undertake large movements across their 
entire range, from the Aleutian Islands to the California coast and use 
numerous portions of this habitat in the spring and summer (Dahlheim et 
al. 2008). The Gulf of Alaska, Aleutian Islands, and Bering Sea 
transient stock occupies a range that includes all of the U.S. EEZ in 
Alaska (Muto et al. 2018), with L-DEO only impacting a portion of this 
range for a limited time period.
    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

    In order to issue an IHA, NMFS must find that the specified 
activity will not have an ``unmitigable adverse impact'' on the 
subsistence uses of the affected marine mammal species or stocks by 
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50 
CFR 216.103 as an impact resulting from the specified activity: (1) 
That is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) Placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) That 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.
    In the GOA, the marine mammals that are hunted are Steller sea 
lions and harbor seals. For seals, these harvests are traditionally low 
from May through August, when harbor seals are raising pups and 
molting. Sea lions are taken from Kodiak Island and other locations in 
the action area in low numbers year round, but harvests are minimal 
during late spring and summer (Wolfe et al. 2012).
    L-DEO's proposed seismic survey would occur during a period of low 
harbor seal and Stellar sea lion harvest, so any impact on subsistence 
activities will be minimal. Additionally, the survey will occur for 
approximately 18 days, and the portion of the survey that would occur 
in nearshore waters, where

[[Page 14240]]

pinniped harvest is most likely, would be even shorter. L-DEO has also 
planned to conduct outreach to subsistence users in the area, in order 
to determine if potential use conflicts exists and avoid these 
conflicts if possible. This outreach, in combination with mitigation 
measures to avoid Steller sea lion rookeries and haulouts, marine 
mammal monitoring, and establishing exclusion zones, will effectively 
minimize impacts on these marine mammals and resulting impacts on 
subsistence users.
    Based on the description of the specified activity, the measures 
described to minimize adverse effects on the availability of marine 
mammals for subsistence purposes, and the proposed mitigation and 
monitoring measures, NMFS has preliminarily determined that there will 
not be an unmitigable adverse impact on subsistence uses from L-DEO's's 
proposed activities.

Endangered Species Act (ESA)

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 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, in this case with the ESA Interagency 
Cooperation Division, whenever we propose to authorize take for 
endangered or threatened species.
    NMFS is proposing to authorize take of blue whale, fin whale, gray 
whale (WNP DPS), humpback whale (Mexico DPS and Western North Pacific 
DPS), North Pacific right whale, sei whale, sperm whale, and Steller 
sea lion (Western DPS), which are listed under the ESA.
    The Permits and Conservation Division has requested initiation of 
Section 7 consultation with the 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 seismic surveys in the Gulf of 
Alaska in spring/early summer of 2019, provided the previously 
mentioned mitigation, monitoring, and reporting requirements are 
incorporated. A draft of the proposed IHA can be found at https://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 L-DEO's proposed 
survey. We also request comment on the potential for 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 our final decision on the request for MMPA authorization.
    On a case-by-case basis, NMFS may issue a one-year IHA renewal with 
an expedited public comment period (15 days) when (1) another year of 
identical or nearly identical activities as described in the Specified 
Activities section is planned or (2) the activities would not be 
completed by the time the IHA expires and a second IHA would allow for 
completion of the activities beyond that described in the Dates and 
Duration section, provided all of the following conditions are met:
     A request for renewal is received no later than 60 days 
prior to expiration of the current IHA.
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
proposed renewal 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 
because only a subset of the initially analyzed activities remain to be 
completed under the Renewal).
    (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: April 3, 2019.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2019-06886 Filed 4-8-19; 8:45 am]
 BILLING CODE 3510-22-P