[Federal Register Volume 84, Number 111 (Monday, June 10, 2019)]
[Notices]
[Pages 26940-26978]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-12010]



[[Page 26939]]

Vol. 84

Monday,

No. 111

June 10, 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 Marine Geophysical Surveys in the 
Northeast Pacific Ocean; Notice

  Federal Register / Vol. 84 , No. 111 / Monday, June 10, 2019 / 
Notices  

[[Page 26940]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XG948


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Marine Geophysical Surveys in the 
Northeast Pacific Ocean

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 
northeast Pacific Ocean. 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 July 10, 
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: Amy Fowler, 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/permit/incidental-take-authorizations-under-marine-mammal-protection-act. In case of problems accessing these 
documents, please call the contact listed above.

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be provided to the public 
for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of 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 NDAA (Pub. L. 108-136) removed the ``small numbers'' and 
``specified geographical region'' limitations indicated above and 
amended the definition of ``harassment'' as it applies to a ``military 
readiness activity.'' 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 is preparing an Environmental Assessment (EA) to 
consider the environmental impacts associated with the issuance of the 
proposed IHA. NMFS' EA will be made available at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.
    We will review all comments submitted in response to this notice 
prior to concluding our NEPA process or making a final decision on the 
IHA request.

Summary of Request

    On December 21, 2018, NMFS received a request from L-DEO for an IHA 
to take marine mammals incidental to a marine geophysical survey of the 
Axial Seamount in the Northeast Pacific Ocean. The application was 
deemed adequate and complete on May 3, 2019. L-DEO's request is for 
take of a small number of 26 species of marine mammals by Level B 
harassment and Level A harassment. Neither L-DEO nor NMFS expects 
serious injury or mortality to result from this activity and, 
therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

    Researchers from the University of Texas at Austin, University of 
Nevada Reno, University of California San Diego, with funding from the 
U.S. National Science Foundation (NSF), propose to conduct high-energy 
seismic surveys from Research Vessel (R/V) Marcus G. Langseth 
(Langseth) in the Northeast Pacific Ocean during summer 2019. The NSF-
owned Langseth is operated by Columbia University's L-DEO under an 
existing Cooperative Agreement. The proposed two-dimensional (2-D) and 
three-dimensional (3-D) seismic surveys would occur in International 
Waters outside of the U.S. Exclusive Economic

[[Page 26941]]

Zone (EEZ). The 2-D survey would use a 36-airgun towed array with a 
total discharge volume of ~6,600 cubic inches (in\3\); the 3-D survey 
would employ an 18-airgun array with a discharge volume of ~3,300 
in\3\.
    The primary objectives of the surveys proposed by researchers from 
the University of Texas at Austin Institute for Geophysics (UTIG), the 
Nevada Seismological Laboratory at the University of Nevada Reno (UNR) 
and Scripps Institution of Oceanography (SIO) at the University of 
California San Diego, is to create a detailed 3-D image of the main and 
satellite magma reservoirs that set the Axial volcano's framework, 
image the 3-D fracture network and how they influence the magma bodies, 
and to connect the subsurface observations to the surface features. The 
main goal of the seismic program is to explore linkages between complex 
magma chamber structure, caldera dynamics, fluid pathways, and 
hydrothermal venting. Seismic data acquired during the proposed study 
could be used to evaluate earthquake, tsunami, and submarine landslide 
hazards.

Dates and Duration

    The proposed surveys would be expected to last for 33 days, 
including approximately 19 days of seismic operations (approximately 16 
days for the 3-D survey and three days for the 2-D survey), seven days 
of equipment deployment/retrieval, three days of operational 
contingency time (e.g., infill, weather delays, etc.), two days for 
turns (no airguns firing) during the 3-D survey, and roughly two days 
of transit. R/V Langseth would leave out of and return to port in 
Astoria, OR, during summer (July/August) 2019.

Specific Geographic Region

    The proposed surveys would occur within ~45.5-46.5[deg] N, ~129.5-
130.5[deg] W. Representative survey tracklines are shown in Figure 1. 
Some deviation in actual track lines, including the order of survey 
operations, could be necessary for reasons such as science drivers, 
poor data quality, inclement weather, or mechanical issues with the 
research vessel and/or equipment. Thus, the tracklines could occur 
anywhere within the coordinates noted above. The proposed surveys would 
be conducted in International Waters outside the U.S. EEZ. The surveys 
would occur in water depths ranging from 1,400 to 2,800 meters (m). The 
proposed survey area is approximately 423 kilometers (km) (229 miles 
(mi)) from shore at its closest point.
[GRAPHIC] [TIFF OMITTED] TN10JN19.000


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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, R/V Langseth, which is owned by NSF and operated on its behalf 
by L-DEO.
    R/V Langseth would first deploy four 6-km streamers and 18 airguns 
to conduct the 3-D multichannel seismic survey to examine the Axial 
volcano and associated rift axes within an approximate 17 x 40 km area. 
The 3-D survey would consist of a racetrack formation with 57 40-km 
long lines and a turning diameter of 8.5 km (Figure 1); no airguns 
would be firing during turns. The survey speed would be ~4.5 knots (kn) 
(8.3 km/hour) for the 3-D survey. The airgun array and streamers would 
then be recovered, and one 15-km streamer would be deployed along with 
36 airguns to acquire eight ~26-km-long source-receiver offset 2-D 
reflection profiles that would look at deep-seated structure of magma 
delivery. During the 2-D survey, the airguns would be firing during 
turns to the next line, and the survey speed would be ~4.2 kn (7.8 km/
hour).
    The receiving system would consist of hydrophone streamers and up 
to eight ocean bottom seismometers (OBSs). The OBSs are long-term 
broadband instruments that would be left out for ~1 year and recovered 
by another vessel. They have a height and diameter of ~1 m, with an 80 
kg anchor. To retrieve OBSs, an acoustic release transponder (pinger) 
is used to interrogate the instrument at a frequency of 8-11 kHz, and a 
response is received at a frequency of 11.5-13 kHz. The burn-wire 
release assembly is then activated, and the instrument is released to 
float to the surface from the anchor which is not retrieved. Four 6-km 
long hydrophone streamers would be used during 3-D data acquisition and 
one 15-km long streamer would be employed for 2-D data acquisition. As 
the airguns are towed along the survey lines, the hydrophone 
streamer(s) would transfer the data to the on-board processing system, 
and the OBSs would receive and store the returning acoustic signals 
internally for later analysis.
    A total of ~3,760 km of transect lines would be surveyed in the 
Northeast Pacific Ocean: ~3,196 km during the 3-D survey (including run 
ins and run outs) and 564 km during the 2-D survey. 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.
    In addition to the operations of the airgun array, a multibeam 
echosounder (MBES), a sub-bottom profiler (SBP), and an Acoustic 
Doppler Current Profiler (ADCP) would be operated from R/V Langseth 
continuously during the seismic surveys, but not during transit to and 
from the survey area. 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.
    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 (SARs; 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 survey area 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 (2016). 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.
    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, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS's U.S. Pacific and Alaska SARs (Caretta et al., 2018; Muto 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 (Caretta et 
al., 2018; Muto 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).

                                               Table 1--Marine Mammals That Could Occur in the Survey Area
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                                                                                  ESA/ MMPA       Stock abundance
                                                                                   status;        (CV, Nmin, most
           Common name                Scientific name            Stock         strategic (Y/N)    recent abundance          PBR          Annual M/SI \3\
                                                                                     \1\            survey) \2\
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family Eschrichtiidae:
    Gray whale...................  Eschrichtius          Eastern North         -/-; N           26,960 (0.05,        801..............  138
                                    robustus.             Pacific.                               25,849, 2016).
                                                         Western North         E/D; Y           175 (0.05, 167,      0.07.............  Unknown
                                                          Pacific.                               2016).
Family Balaenidae:
    North Pacific right whale....  Eubalaena japonica..  Eastern North         E/D; Y           31 (0.226, 26,       0.05.............  0
                                                          Pacific.                               2015).

[[Page 26943]]

 
Family Balaenopteridae
 (rorquals):
    Humpback whale...............  Megaptera             California/Oregon/    -/-; Y           1,918 (0.03, 1,876,  11...............  >9.2
                                    novaeangliae.         Washington.                            2014).
    Minke whale..................  Balaenoptera          California/Oregon/    -/-; N           636 (0.72, 369,      3.5..............  >1.3
                                    acutorostrata.        Washington.                            2014).
    Sei whale....................  Balaenoptera          Eastern North         E/D; Y           519 (0.4, 374,       0.75.............  0
                                    borealis.             Pacific.                               2014).
    Fin whale....................  Balaenoptera          California/Oregon/    E/D; Y           9,029 (0.12, 8,127,  81...............  >2.0
                                    physalus.             Washington.                            2014).
    Blue whale...................  Balaenoptera          Eastern North         E/D; Y           1,647 (0.07, 1,551,  2.3..............  >0.2
                                    musculus.             Pacific.                               2011).
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                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale..................  Physeter              California/Oregon/    E/D; Y           1,967 (0.57, 1,270,  2.5..............  0.9
                                    macrocephalus.        Washington.                            2014).
Family Kogiidae:
    Pygmy sperm whale............  Kogia breviceps.....  California/Oregon/    -/-; N           4,111 (1.12, 1,924,  19...............  0
                                                          Washington.                            2014).
    Dwarf sperm whale............  Kogia sima..........  California/Oregon/    -/-; N           Unknown (Unknown,    Undetermined.....  0
                                                          Washington.                            Unknown, 2014).
Family Ziphiidae (beaked whales):
    Cuvier's beaked whale........  Ziphius cavirostris.  California/Oregon/    -/-; N           3,274 (0.67, 2,059,  21...............  <0.1
                                                          Washington.                            2014).
    Baird's beaked whale.........  Berardius bairdii...  California/Oregon/    -/-; N           2,697 (0.6, 1,633,   16...............  0
                                                          Washington.                            2014).
    Blainville's beaked whale....  Mesoplodon            California/Oregon/    -/-; N           3,044 (0.54, 1,967,  20...............  0.1
                                    densirostris.         Washington.                            2014).
    Hubbs' beaked whale..........  Mesoplodon
                                    carlshubbi.
    Stejneger's beaked whale.....  Mesoplodon
                                    stejnegeri.
Family Delphinidae:
    Bottlenose dolphin...........  Tursiops truncatus..  California/Oregon/    -/-; N           1,924 (0.54, 1,255,  11...............  >1.6
                                                          Washington offshore.                   2014).
    Striped dolphin..............  Stenella              California/Oregon/    -/-; N           29,211 (0.2,         238..............  > 0.8
                                    coeruleoalba.         Washington.                            24,782, 2014).
    Short-beaked common dolphin..  Delphinus delphis...  California/Oregon/    -/-; N           969,861 (0.17,       8,393............  >40
                                                          Washington.                            839,325, 2014).
    Pacific white-sided dolphin..  Lagenorhynchus        California/Oregon/    -/-; N           26,814 (0.28,        191..............  7.5
                                    obliquidens.          Washington.                            21,195, 2014).
    Northern right whale dolphin.  Lissodelphis          California/Oregon/    -/-; N           26,556 (0.44,        179..............  3.8
                                    borealis.             Washington.                            18,608, 2014).
    Risso's dolphin..............  Grampus griseus.....  California/Oregon/    -/-; N           6,336 (0.32, 4,817,  46...............  >3.7
                                                          Washington.                            2014).
    False killer whale...........  Pseudorca crassidens  Hawaii Pelagic......  -/-; N           1,540 (0.66, 928,    9.3..............  7.6
                                                                                                 2010).
    Killer whale.................  Orcinus orca........  Offshore............  -/-; N           240 (0.49, 162,      1.6..............  0
                                                         Southern Resident...  E/D; Y            2014).              0.14.............  0
                                                         Northern Resident...  -/-; N           83 (N/A, 83, 2016).  1.96.............  0
                                                         West Coast Transient  -/-; N           261 (N/A, 261,       2.4..............  0
                                                                                                 2011).
                                                                                                243 (N/A, 243,
                                                                                                 2009).
    Short-finned pilot whale.....  Globicephala          California/Oregon/    -/-; N           836 (0.79, 466,      4.5..............  1.2
                                    macrorhynchus.        Washington.                            2014).
Family Phocoenidae (porpoises):
    Harbor porpoise..............  Phocoena phocoena...  Northern Oregon/      -/-; N           21,487 (0.44,        151..............  >3.0
                                                          Washington Coast.                      15,123, 2011).
    Dall's porpoise..............  Phocoenoides dalli..  California/Oregon/    -/-; N           25,750 (0.45,        172..............  0.3
                                                          Washington.                            17,954, 2014).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Northern fur seal............  Callorhinus ursinus.  Eastern Pacific.....  -/D; Y           620,660 (0.2,        11,295...........  457
                                                         California..........  -/D; N            525,333, 2016).     451..............  1.8
                                                                                                14,050 (N/A, 7,524,
                                                                                                 2013).
    California sea lion..........  Zalophus              U.S.................  -/-; N           257,606 (N/A,        14,011...........  >197
                                    californianus.                                               233,515, 2014).
    Steller sea lion.............  Eumetopias jubatus..  Eastern U.S.........  -/-; N           41,638 (see SAR,     2,498............  108
                                                                                                 41,638, 2015).
    Guadalupe fur seal...........  Arctocephalus         Mexico..............  T/D; Y           20,000 (N/A,         542..............  >3.2
                                    townsendi.                                                   15,830, 2010).
Family Phocidae (earless seals):
    Harbor seal..................  Phoca vitulina......  Oregon/Washington     -/-; N           Unknown (Unknown,    Undetermined.....  10.6
                                                          Coastal.                               Unknown, 1999).

[[Page 26944]]

 
    Northern elephant seal.......  Mirounga              California Breeding.  -/-; N           179,000 (N/A,        4,882............  8.8
                                    angustirostris.                                              81,368, 2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance. In some cases, CV is not applicable.
\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). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
Note: Italicized species 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. However, the temporal and/or spatial 
occurrence of gray whales, Southern Resident and Northern Resident 
killer whales, harbor porpoise, harbor seal, California sea lion, and 
Steller sea lion is such that take is not expected to occur, and they 
are not discussed further beyond the explanation provided here. These 
species are found in the eastern North Pacific, but are generally found 
in coastal waters and are not expected to occur offshore in the survey 
area.

Humpback Whale

    The humpback whale is found throughout all of the oceans of the 
world (Clapham 2009). The worldwide population of humpbacks is divided 
into northern and southern ocean populations, but genetic analyses 
suggest some gene flow (either past or present) between the North and 
South Pacific (e.g., Baker et al., 1993; Caballero et al., 2001). 
Geographical overlap of these populations has been documented only off 
Central America (Acevedo and Smultea 1995; Rasmussen et al., 2004, 
2007). Although considered to be mainly a coastal species, humpback 
whales often traverse deep pelagic areas while migrating (Clapham and 
Mattila 1990; Norris et al., 1999; Calambokidis et al., 2001).
    Humpback whales migrate between summer feeding grounds in high 
latitudes and winter calving and breeding grounds in tropical waters 
(Clapham and Mead 1999). North Pacific humpback whales summer in 
feeding grounds along the Pacific Rim and in the Bering and Okhotsk 
seas (Pike and MacAskie 1969; Rice 1978; Winn and Reichley 1985; 
Calambokidis et al., 2000, 2001, 2008). 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; Bettridge et al., 2015). These breeding areas have been 
designated as DPSs, but feeding areas have no DPS status (Bettridge et 
al., 2015; NMFS 2016b). Individuals encountered in the proposed survey 
area most likely would come from the Central America and Mexico 
distinct population segments (DPSs), although some individuals from the 
Hawaii DPS may also feed in these waters. There is a low level of 
interchange of whales among the main wintering areas and among feeding 
areas (e.g., Darling and Cerchio 1993; Salden et al., 1999; 
Calambokidis et al., 2001, 2008).
    The humpback whale is the most common species of large cetacean 
reported off the coasts of Oregon and Washington from May to November 
(Green et al., 1992; Calambokidis et al., 2000, 2004). The highest 
numbers have been reported off Oregon during May and June and off 
Washington during July-September. However, off Oregon and Washington, 
humpbacks occur primarily over the continental shelf and slope during 
the summer, with few reported in offshore pelagic waters (Green et al., 
1992; Calambokidis et al., 2004, 2015; Becker et al., 2012; Menza et 
al., 2016). Biologically important areas (BIAs) for feeding humpback 
whales along the coasts of Oregon and Washington, which have been 
designated from May to November, are all within ~80 km offshore 
(Calambokidis et al., 2015).

Minke Whale

    The minke whale has a cosmopolitan distribution that spans from 
tropical to polar regions in both hemispheres (Jefferson et al., 2015). 
In the Northern Hemisphere, the minke whale is usually seen in coastal 
areas, but can also be seen in pelagic waters during its northward 
migration in spring and summer and southward migration in autumn 
(Stewart and Leatherwood 1985). In the North Pacific, the summer range 
of the minke whale extends to the Chukchi Sea; in the winter, the 
whales move farther south to within 2[deg] of the Equator (Perrin and 
Brownell 2009).
    The International Whaling Commission (IWC) recognizes three stocks 
of minke whales 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). Minke whales are relatively common in 
the Bering and Chukchi seas and in the Gulf of Alaska, but are not 
considered abundant in any other part of the eastern Pacific 
(Brueggeman et al., 1990). In the far north, minke whales are thought 
to be migratory, but they are believed to be year-round residents in 
coastal waters off the U.S. West Coast (Dorsey et al., 1990).

Sei Whale

    The distribution of the sei whale is not well known, but it is 
found in all oceans and appears to prefer mid-latitude temperate waters 
(Jefferson et al., 2015). The sei whale is pelagic and generally not 
found in coastal waters (Jefferson et al., 2015). It is found 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., 1999a). Sei whales migrate from temperate zones occupied 
in winter to higher latitudes in the summer, where most feeding takes 
place (Gambell 1985a). During summer in the North Pacific, the sei 
whale can be found from the Bering Sea to the Gulf of Alaska and down 
to southern

[[Page 26945]]

California, as well as in the western Pacific from Japan to Korea. Its 
winter distribution is concentrated at ~20[deg] N (Rice 1998).

Fin Whale

    The fin whale is widely distributed in all the world's oceans 
(Gambell 1985b), but typically occurs in temperate and polar regions 
from 20-70[deg] north and south of the Equator (Perry et al., 1999b). 
Northern and southern fin whale populations are distinct and are 
sometimes recognized as different subspecies (Aguilar 2009). Fin whales 
occur in coastal, shelf, and oceanic waters. Sergeant (1977) suggested 
that fin whales tend to follow steep slope contours, either because 
they detect them readily or because biological productivity is high 
along steep contours because of tidal mixing and perhaps current 
mixing. Stafford et al., (2009) noted that sea-surface temperature is a 
good predictor variable for fin whale call detections in the North 
Pacific.
    Fin whales appear to have complex seasonal movements and are 
seasonal migrants; they mate and calve in temperate waters during the 
winter and migrate to feed at northern latitudes during the summer 
(Gambell 1985b). The North Pacific population summers from the Chukchi 
Sea to California and winters from California southwards (Gambell 
1985b). Aggregations of fin whales are found year-round off southern 
and central California (Dohl et al., 1980, 1983; Forney et al., 1995; 
Barlow 1997) and in the summer off Oregon (Green et al., 1992; Edwards 
et al., 2015). Vocalizations from fin whales have also been detected 
year-round off northern California, Oregon, and Washington (Moore et 
al., 1998, 2006; Watkins et al., 2000a, b; Stafford et al., 2007, 2009; 
Edwards et al., 2015).

Blue Whale

    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). Although it has been suggested that there are at least 
five subpopulations of blue whales in the North Pacific (NMFS 1998), 
analysis of blue whale calls monitored from the U.S. Navy Sound 
Surveillance System (SOSUS) and other offshore hydrophones (see 
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 western North Pacific (Sears and Perrin 2009). 
Broad-scale acoustic monitoring indicates that blue whales occurring in 
the northeast Pacific during summer and fall may winter in the eastern 
tropical Pacific (Stafford et al., 1999, 2001).
    The distribution of the species, at least during times of the year 
when feeding is a major activity, occurs in areas that provide large 
seasonal concentrations of euphausiids (Yochem and Leatherwood 1985). 
The eastern North Pacific stock feeds in California waters from June-
November (Calambokidis et al., 1990; Mate et al., 1999). There are nine 
BIAs for feeding blue whales off the coast of California (Calambokidis 
et al., 2015), and core areas have also been identified there (Irvine 
et al., 2014). Blue whales have been detected acoustically off Oregon 
(McDonald et al., 1995; Stafford et al., 1998; Von Saunder and Barlow 
1999), but sightings are uncommon (Carretta et al., 2018). Densities 
along the U.S. West Coast, including Oregon, were predicted to be 
highest in shelf waters, with lower densities in deeper offshore areas 
(Becker et al., 2012; Calambokidis et al., 2015). Buchanan et al., 
(2001) considered blue whales to be rare off Oregon and Washington. 
However, based on the absolute dynamic topography of the region, blue 
whales could occur in relatively high densities off Oregon during July-
December (Pardo et al., 2015).

Sperm Whale

    The sperm whale is the largest of the toothed whales, with an 
extensive worldwide distribution (Rice 1989). Sperm whale distribution 
is linked to social structure: Mixed groups of adult females and 
juvenile animals of both sexes generally occur in tropical and 
subtropical waters, whereas adult males are commonly found alone or in 
same-sex aggregations, often occurring in higher latitudes outside the 
breeding season (Best 1979; Watkins and Moore 1982; Arnbom and 
Whitehead 1989; Whitehead and Waters 1990). Males can migrate north in 
the summer to feed in the Gulf of Alaska, Bering Sea, and waters around 
the Aleutian Islands (Kasuya and Miyashita 1988). Mature male sperm 
whales migrate to warmer waters to breed when they are in their late 
twenties (Best 1979).
    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; Whitehead 2009). They 
are often found far from shore, but can be found closer to oceanic 
islands that rise steeply from deep ocean waters (Whitehead 2009). 
Adult males can occur in water depths <100 m and as shallow as 40 m 
(Whitehead et al. 1992; Scott and Sadove 1997). They can dive as deep 
as ~2 km and possibly deeper on rare occasions for periods of over 1 h; 
however, most of their foraging occurs at depths of ~300-800 m for 30-
45 min (Whitehead 2003).
    Sperm whales are distributed widely across the North Pacific (Rice 
1989). Off California, they occur year-round (Dohl et al., 1983; Barlow 
1995; Forney et al., 1995), with peak abundance from April to mid-June 
and from August to mid-November (Rice 1974). Off Oregon, sperm whales 
are seen in every season except winter (Green et al., 1992).
    Oleson et al. (2009) noted a significant diel pattern in the 
occurrence of sperm whale clicks at offshore and inshore monitoring 
locations off Washington, whereby clicks were more commonly heard 
during the day at the offshore site and were more common at night at 
the inshore location, suggesting possible diel movements up and down 
the slope in search of prey. Sperm whale acoustic detections were also 
reported at the inshore site from June through January 2009, with an 
absence of calls during February to May ([Scirc]irovi[cacute] et al., 
2012). In addition, sperm whales were sighted during surveys off 
Washington in June 2011 and off Oregon in October 2011 (Adams et al., 
2014).

Pygmy and Dwarf Sperm Whales

    The pygmy and dwarf sperm whales are distributed widely throughout 
tropical and temperate seas, but their precise distributions are 
unknown as most information on these species comes from strandings 
(McAlpine 2009). They are difficult to sight at sea, perhaps because of 
their avoidance reactions to ships and behavior changes in relation to 
survey aircraft (W[uuml]rsig et al., 1998). The two species are 
difficult to distinguish from one another when sighted (McAlpine 2009).
    Both Kogia species are sighted primarily along the continental 
shelf edge and slope and over deeper waters off the shelf (Hansen et 
al., 1994; Davis et al., 1998). Several studies have suggested that 
pygmy sperm whales live mostly beyond the continental shelf edge, 
whereas dwarf sperm whales tend to occur closer to shore, often over 
the continental shelf (Rice 1998; Wang et al., 2002; MacLeod et al., 
2004). Barros et al., (1998), on the other hand, suggested that dwarf 
sperm whales could be more pelagic and dive deeper than pygmy sperm 
whales. It has also been suggested that the pygmy sperm whale is more 
temperate and the dwarf sperm whale more tropical, based at least 
partially on live sightings at sea from a large database from the 
eastern tropical Pacific (Wade and Gerrodette 1993). This idea is also 
supported by the

[[Page 26946]]

distribution of strandings in South American waters (Mu[ntilde]oz-
Hincapi[eacute] et al., 1998).

Cuvier's Beaked Whale

    Cuvier's beaked whale is probably the most widespread of the beaked 
whales, although it is not found in polar waters (Heyning 1989). 
Cuvier's beaked whale appears to prefer steep continental slope waters 
(Jefferson et al., 2015) and is most common in water depths >1,000 m 
(Heyning 1989). It is mostly known from strandings and strands more 
commonly than any other beaked whale (Heyning 1989). Its inconspicuous 
blows, deep-diving behavior, and tendency to avoid vessels all help to 
explain the infrequent sightings (Barlow and Gisiner 2006). The 
population in the California Current Large Marine Ecosystem seems to be 
declining (Moore and Barlow 2013).
    MacLeod et al., (2006) reported numerous sightings and strandings 
along the Pacific coast of the U.S. Cuvier's beaked whale is the most 
common beaked whale off the U.S. West Coast (Barlow 2010), and it is 
the beaked whale species that has stranded most frequently on the 
coasts of Oregon and Washington. From 1942-2010, there were 23 reported 
Cuvier's beaked whale strandings in Oregon and Washington (Moore and 
Barlow 2013). Most (75 percent) Cuvier's beaked whale strandings 
reported occurred in Oregon (Norman et al., 2004).

Blainville's Beaked Whale

    Blainville's beaked whale is found in tropical and warm temperate 
waters of all oceans (Pitman 2009). It has the widest distribution 
throughout the world of all mesoplodont species and appears to be 
relatively common (Pitman 2009). Like other beaked whales, Blainville's 
beaked whale is generally found in waters 200-1400 m deep (Gannier 
2000; Jefferson et al., 2015). Occasional occurrences in cooler, 
higher-latitude waters are presumably related to warm-water incursions 
(Reeves et al., 2002). MacLeod et al., (2006) reported stranding and 
sighting records in the eastern Pacific ranging from 37.3[deg] N to 
41.5[deg] S. However, none of the 36 beaked whale stranding records in 
Oregon and Washington during 1930-2002 included Blainville's beaked 
whale (Norman et al., 2004). One Blainville's beaked whale was found 
stranded (dead) on the Washington coast in November 2016 (COASST 2016).

Stejneger's Beaked Whale

    Stejneger's beaked whale occurs in subarctic and cool temperate 
waters of the North Pacific Ocean (Mead 1989). In the eastern North 
Pacific Ocean, it is distributed from Alaska to southern California 
(Mead et al., 1982; Mead 1989). Most stranding records are from Alaskan 
waters, and the Aleutian Islands appear to be its center of 
distribution (MacLeod et al., 2006). After Cuvier's beaked whale, 
Stejneger's beaked whale was the second most commonly stranded beaked 
whale species in Oregon and Washington (Norman et al., 2004).

Hubb's Beaked Whale

    Hubbs' beaked whale occurs in temperate waters of the North Pacific 
(Mead 1989). Its distribution appears to be correlated with the deep 
subarctic current (Mead et al., 1982). Numerous stranding records have 
been reported for the U.S. West Coast (MacLeod et al., 2006). Most of 
the records are from California, but it has been sighted as far north 
as Prince Rupert, British Columbia (Mead 1989). Two strandings are 
known from Washington/Oregon (Norman et al., 2004). Hubbs' beaked 
whales are often killed in drift gillnets off California (Reeves et 
al., 2002).
    There are no sightings of Hubbs' beaked whales near the proposed 
survey area in the OBIS database (OBIS 2018). There is one sighting of 
an unidentified species of Mesoplodont whale near the survey area in 
the OBIS database that was made in July 1996 during the SWFSC ORCAWALE 
Marine Mammal Survey (OBIS 2018). During the 2016 SWFSC PASCAL study 
using drifting acoustic recorders, detections were made of beaked whale 
sounds presumed to be from Hubbs' beaked whales near the proposed 
survey area during August (Griffiths et al., submitted manuscript cited 
in Keating et al., 2018). In addition, at least two sightings just to 
the south of the proposed survey area were reported in Carretta et al., 
(2018). This species seems to be less common in the proposed survey 
area than some of the other beaked whales.

Baird's Beaked Whale

    Baird's beaked whale has a fairly extensive range across the North 
Pacific, with concentrations occurring in the Sea of Okhotsk and Bering 
Sea (Rice 1998; Kasuya 2009). In the eastern Pacific, Baird's beaked 
whale is reported to occur as far south as San Clemente Island, 
California (Rice 1998; Kasuya 2009). Baird's beaked whales that occur 
off the U.S. west coast are of the gray form, unlike some Berardius 
individuals that are found in Alaska and Japan, which are of the black 
form and thus could be a new species (Morin et al., 2017).

Bottlenose Dolphin

    The bottlenose dolphin is distributed worldwide in coastal and 
shelf waters of tropical and temperate oceans (Jefferson et al., 2015). 
There are two distinct bottlenose dolphin types: A shallow water type, 
mainly found in coastal waters, and a deep water type, mainly found in 
oceanic waters (Duffield et al., 1983; Hoelzel et al., 1998; Walker et 
al., 1999). Coastal common bottlenose dolphins exhibit a range of 
movement patterns including seasonal migration, year-round residency, 
and a combination of long-range movements and repeated local residency 
(Wells and Scott 2009).

Short-Beaked Common Dolphin

    The short-beaked common dolphin is found in tropical and warm 
temperate oceans around the world (Perrin 2009). It ranges as far south 
as 40[deg] S in the Pacific Ocean, is common in coastal waters 200-300 
m deep and is also associated with prominent underwater topography, 
such as seamounts (Evans 1994). Short-beaked common dolphins have been 
sighted as far as 550 km from shore (Barlow et al., 1997).
    The distribution of short-beaked common dolphins along the U.S. 
West Coast is variable and likely related to oceanographic changes 
(Heyning and Perrin 1994; Forney and Barlow 1998). It is the most 
abundant cetacean off California; some sightings have been made off 
Oregon, in offshore waters (Carretta et al., 2017). During surveys off 
the west coast in 2014 and 2017, sightings were made as far north as 
44[deg] N (Barlow 2016; SIO n.d.). Based on the absolute dynamic 
topography of the region, short-beaked common dolphins could occur in 
relatively high densities off Oregon during July-December (Pardo et 
al., 2015). In contrast, habitat modeling predicted moderate densities 
of common dolphins off the Columbia River mouth during summer, with 
lower densities off southern Oregon (Becker et al., 2014).

Striped Dolphin

    The striped dolphin has a cosmopolitan distribution in tropical to 
warm temperate waters (Perrin et al., 1994) and is generally seen south 
of 43[deg] N (Archer 2009). However, in the eastern North Pacific, its 
distribution extends as far north as Washington (Jefferson et al., 
2015). The striped dolphin is typically found in waters outside the 
continental shelf and is often associated with convergence zones and 
areas of upwelling (Archer 2009). However, it has also been observed 
approaching shore where there is deep

[[Page 26947]]

water close to the coast (Jefferson et al., 2015).

Pacific White-Sided Dolphin

    The Pacific white-sided dolphin is found in cool temperate waters 
of the North Pacific from the southern Gulf of California to Alaska. 
Across the North Pacific, it appears to have a relatively narrow 
distribution between 38[deg] N and 47[deg] N (Brownell et al., 1999). 
In the eastern North Pacific Ocean, including waters off Oregon, the 
Pacific white-sided dolphin is one of the most common cetacean species, 
occurring primarily in shelf and slope waters (Green et al., 1993; 
Barlow 2003, 2010). It is known to occur close to shore in certain 
regions, including (seasonally) southern California (Brownell et al., 
1999).
    Results of aerial and shipboard surveys strongly suggest seasonal 
north-south movements of the species between California and Oregon/
Washington; the movements apparently are related to oceanographic 
influences, particularly water temperature (Green et al., 1993; Forney 
and Barlow 1998; Buchanan et al., 2001). During winter, this species is 
most abundant in California slope and offshore areas; as northern 
waters begin to warm in the spring, it appears to move north to slope 
and offshore waters off Oregon/Washington (Green et al., 1992, 1993; 
Forney 1994; Forney et al., 1995; Buchanan et al., 2001; Barlow 2003). 
The highest encounter rates off Oregon and Washington have been 
reported during March-May in slope and offshore waters (Green et al., 
1992). Similarly, Becker et al., (2014) predicted relatively high 
densities off southern Oregon in shelf and slope waters.
    Based on year-round aerial surveys off Oregon/Washington, the 
Pacific white-sided dolphin was the most abundant cetacean species, 
with nearly all (97 percent) sightings occurring in May (Green et al., 
1992, 1993). Barlow (2003) also found that the Pacific white-sided 
dolphin was one of the most abundant marine mammal species off Oregon/
Washington during 1996 and 2001 ship surveys, and it was the second 
most abundant species reported during 2008 surveys (Barlow 2010). Adams 
et al., (2014) reported numerous offshore sightings off Oregon during 
summer, fall, and winter surveys in 2011 and 2012. Based on surveys 
conducted during 2014, the abundance was estimated at 20,711 for 
Oregon/Washington (Barlow 2016).

Northern Right Whale Dolphin

    The northern right whale dolphin is found in cool temperate and 
sub-arctic waters of the North Pacific, from the Gulf of Alaska to near 
northern Baja California, ranging from 30[deg] N to 50[deg] N (Reeves 
et al., 2002). In the eastern North Pacific Ocean, including waters off 
Oregon, the northern right whale dolphin is one of the most common 
marine mammal species, occurring primarily in shelf and slope waters 
~100 to >2,000 m deep (Green et al., 1993; Barlow 2003). The northern 
right whale dolphin comes closer to shore where there is deep water, 
such as over submarine canyons (Reeves et al., 2002).
    Aerial and shipboard surveys suggest seasonal inshore-offshore and 
north-south movements in the eastern North Pacific Ocean between 
California and Oregon/Washington; the movements are believed to be 
related to oceanographic influences, particularly water temperature and 
presumably prey distribution and availability (Green et al., 1993; 
Forney and Barlow 1998; Buchanan et al., 2001). Green et al., (1992, 
1993) found that northern right whale dolphins were most abundant off 
Oregon/Washington during fall, less abundant during spring and summer, 
and absent during winter, when this species presumably moves south to 
warmer California waters (Green et al., 1992, 1993; Forney 1994; Forney 
et al., 1995; Buchanan et al., 2001; Barlow 2003). Considerable 
interannual variations in abundance also have been found.
    Becker et al., (2014) predicted relatively high densities off 
southern Oregon, and moderate densities off northern Oregon and 
Washington. Based on year-round aerial surveys off Oregon/Washington, 
the northern right whale dolphin was the third most abundant cetacean 
species, concentrated in slope waters but also occurring in water out 
to ~550 km offshore (Green et al., 1992, 1993). Barlow (2003, 2010) 
also found that the northern right whale dolphin was one of the most 
abundant marine mammal species off Oregon/Washington during 1996, 2001, 
2005, and 2008 ship surveys. Offshore sightings were made in the waters 
of Oregon during summer, fall, and winter surveys in 2011 and 2012 
(Adams et al., 2014).

Risso's Dolphin

    Risso's dolphin is distributed worldwide in temperate and tropical 
oceans (Baird 2009), although it shows a preference for mid-temperate 
waters of the shelf and slope between 30[deg] and 45[deg] (Jefferson et 
al., 2014). Although it is known to occur in coastal and oceanic 
habitats (Jefferson et al., 2014), it appears to prefer steep sections 
of the continental shelf, 400-1,000 m deep (Baird 2009), and is known 
to frequent seamounts and escarpments (Kruse et al., 1999). Off the 
U.S. West Coast, 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).
    The distribution and abundance of Risso's dolphins are highly 
variable from California to Washington, presumably in response to 
changing oceanographic conditions on both annual and seasonal time 
scales (Forney and Barlow 1998; Buchanan et al., 2001). The highest 
densities were predicted along the coasts of Washington, Oregon, and 
central and southern California (Becker et al., 2012). Off Oregon and 
Washington, Risso's dolphins are most abundant over continental slope 
and shelf waters during spring and summer, less so during fall, and 
rare during winter (Green et al., 1992, 1993). Green et al., (1992, 
1993) reported most Risso's dolphin groups off Oregon between ~45 and 
47[deg] N. Several sightings were made off southern Oregon during 
surveys in 1991-2014 (Carretta et al., 2017). Sightings during ship 
surveys in summer/fall 2008 were mostly between ~30 and 38[deg] N; none 
were reported in Oregon/Washington (Barlow 2010). Based on 2014 survey 
data, the abundance for Oregon/Washington was estimated at 430 (Barlow 
2016).

False Killer Whale

    The false killer whale is found in all tropical and warmer 
temperate oceans, especially in deep, offshore waters (Odell and 
McClune 1999). However, it is also known to occur in nearshore areas 
(e.g., Stacey and Baird 1991). In the eastern North Pacific, it has 
been reported only rarely north of Baja California (Leatherwood et al., 
1982, 1987; Mangels and Gerrodette 1994); however, the waters off the 
U.S. West Coast all the way north to Alaska are considered part of its 
secondary range (Jefferson et al., 2015). Its occurrence in Washington/
Oregon is associated with warm-water incursions (Buchanan et al., 
2001). One pod of false killer whales occurred in Puget Sound for 
several months during the 1990s (USN 2015). Two were reported stranded 
along the Washington coast during 1930-2002, both in El Ni[ntilde]o 
years (Norman et al., 2004). One sighting was made off southern 
California during 2014 (Barlow 2016).

[[Page 26948]]

Killer Whale

    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). Currently, there are eight 
killer whale stocks recognized in the U.S. Pacific: (1) Alaska 
Residents, occurring from southeast Alaska to the Aleutians and Bering 
Sea; (2) Northern Residents, from BC through parts of southeast Alaska; 
(3) Southern Residents, mainly in inland waters of Washington State and 
southern BC; (4) Gulf of Alaska, Aleutians, and Bering Sea Transients, 
from Prince William Sound (PWS) through to the Aleutians and Bering 
Sea; (5) AT1 Transients, from PWS through the Kenai Fjords; (6) West 
Coast Transients, from California through southeast Alaska; (7) 
Offshore, from California through Alaska; and (8) Hawaiian (Carretta et 
al., 2018). Individuals from the Offshore and West Coast Transient 
stocks could be encountered in the proposed project area.
    Green et al. (1992) noted that most groups seen during their 
surveys off Oregon and Washington were likely transients; during those 
surveys, killer whales were sighted only in shelf waters. Killer whales 
were sighted off Washington in July and September 2012 (Adams et al., 
2014). Two of 17 killer whales that stranded in Oregon were confirmed 
as transient (Stevens et al., 1989 in Norman et al., 2004).

Short-Finned Pilot Whale

    The short-finned pilot whale is found in tropical, subtropical, and 
warm temperate waters (Olson 2009); it is seen as far south as ~40[deg] 
S and as far north as ~50[deg] N (Jefferson et al., 2015). Pilot whales 
are generally nomadic, but may be resident in certain locations, 
including California and Hawaii (Olson 2009). Short-finned pilot whales 
were common off southern California (Dohl et al., 1980) until an El 
Ni[ntilde]o event occurred in 1982-1983 (Carretta et al., 2017).

Dall's Porpoise

    Dall's porpoise is found in temperate to subantarctic waters of the 
North Pacific and adjacent seas (Jefferson et al., 2015). 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). It 
is probably the most abundant small cetacean in the North Pacific 
Ocean, and its abundance changes seasonally, likely in relation to 
water temperature (Becker 2007).
    Off Oregon and Washington, Dall's porpoise is widely distributed 
over shelf and slope waters, with concentrations near shelf edges, but 
is also commonly sighted in pelagic offshore waters (Morejohn 1979; 
Green et al., 1992; Becker et al., 2014; Carretta et al., 2018). 
Combined results of various surveys out to ~550 km offshore indicate 
that the distribution and abundance of Dall's porpoise varies between 
seasons and years. North-south movements are believed to occur between 
Oregon/Washington and California in response to changing oceanographic 
conditions, particularly temperature and distribution and abundance of 
prey (Green et al., 1992, 1993; Mangels and Gerrodette 1994; Barlow 
1995; Forney and Barlow 1998; Buchanan et al., 2001). Becker et al., 
(2014) predicted high densities off southern Oregon throughout the 
year, with moderate densities to the north. According to predictive 
density distribution maps, the highest densities off southern 
Washington and Oregon occur along the 500-m isobath (Menza et al., 
2016).
    Encounter rates reported by Green et al., (1992) during aerial 
surveys off Oregon/Washington were highest in fall, lowest during 
winter, and intermediate during spring and summer. Encounter rates 
during the summer were similarly high in slope and shelf waters, and 
somewhat lower in offshore waters (Green et al., 1992). Dall's porpoise 
was the most abundant species sighted off Oregon/Washington during 
1996, 2001, 2005, and 2008 ship surveys up to ~550 km from shore 
(Barlow 2003, 2010).

Northern Fur Seal

    The northern fur seal is endemic to the North Pacific Ocean and 
occurs from southern California to the Bering Sea, Sea of Okhotsk, and 
Sea of Japan (Jefferson et al., 2015). The worldwide population of 
northern fur seals has declined substantially from 1.8 million animals 
in the 1950s (Muto et al., 2018). They were subjected to large-scale 
harvests on the Pribilof Islands to supply a lucrative fur trade. Two 
stocks are recognized in U.S. waters: The Eastern North Pacific and the 
California stocks. The Eastern Pacific stock ranges from southern 
California during winter to the Pribilof Islands and Bogoslof Island in 
the Bering Sea during summer (Carretta et al., 2018; Muto et al., 
2018). Abundance of the Eastern Pacific Stock has been decreasing at 
the Pribilof Islands since the 1940s and increasing on Bogoslof Island.
    Most northern fur seals are highly migratory. During the breeding 
season, most of the world's population of northern fur seals occurs on 
the Pribilof and Bogoslof islands (NMFS 2007). The main breeding season 
is in July (Gentry 2009). Adult males usually occur onshore from May to 
August, though some may be present until November; females are usually 
found ashore from June to November (Muto et al., 2018). Nearly all fur 
seals from the Pribilof Island rookeries are foraging at sea from fall 
through late spring. In November, females and pups leave the Pribilof 
Islands and migrate through the Gulf of Alaska to feeding areas 
primarily off the coasts of BC, Washington, Oregon, and California 
before migrating north again to the rookeries in spring (Ream et al., 
2005; Pelland et al., 2014). Immature seals can remain in southern 
foraging areas year-round until they are old enough to mate (NMFS 
2007). Adult males migrate only as far south as the Gulf of Alaska or 
to the west off the Kuril Islands (Kajimura 1984). Pups from the 
California stock also migrate to Washington, Oregon, and northern 
California after weaning (Lea et al., 2009).
    The northern fur seals spends ~90 percent of its time at sea, 
typically in areas of upwelling along the continental slopes and over 
seamounts (Gentry 1981). The remainder of its life is spent on or near 
rookery islands or haulouts. While at sea, northern fur seals usually 
occur singly or in pairs, although larger groups can form in waters 
rich with prey (Antonelis and Fiscus 1980; Gentry 1981). Northern fur 
seals dive to relatively shallow depths to feed: 100-200 m for females, 
and <400 m for males (Gentry 2009). Tagged adult female fur seals were 
shown to remain within 200 km of the shelf break (Pelland et al., 
2014).
    Bonnell et al. (1992) noted the presence of northern fur seals 
year-round off Oregon/Washington, with the greatest numbers (87 
percent) occurring in January-May. Northern fur seals were seen as far 
out from the coast as 185 km, and numbers increased with distance from 
land; they were 5-6 times more abundant in offshore waters than over 
the shelf or slope (Bonnell et al., 1992). The highest densities were 
seen in the Columbia River plume (~46[deg] N) and in deep offshore 
waters (>2,000 m) off central and southern Oregon (Bonnell et al., 
1992). The waters off Washington are a known foraging area for adult 
females, and concentrations of fur seals were also reported to occur 
near Cape Blanco, Oregon, at ~42.8[deg] N (Pelland et al., 2014). 
Tagged adult fur seals were tracked from the Pribilof Islands to the 
waters off Washington/Oregon/California, with recorded movement

[[Page 26949]]

throughout the proposed project area (Pelland et al., 2014).

Guadalupe Fur Seal

    Guadalupe fur seals were once plentiful on the California coast, 
ranging from the Gulf of the Farallones near San Francisco, to the 
Revillagigedo Islands, Mexico (Aurioles-Gamboa et al., 1999), but they 
were over-harvested in the 19th century to near extinction. After being 
protected, the population grew slowly; mature individuals of the 
species were observed occasionally in the Southern California Bight 
starting in the 1960s (Stewart et al., 1993), and, in 1997, a female 
and pup were observed on San Miguel Island (Melin & DeLong, 1999). 
Since then, a small group has persisted in that area (Aurioles-Gamboa 
et al., 2010).
    The distribution of Guadalupe fur seals and occurrence in the 
survey area is dependent on life stage and season. During the breeding 
season, June through August, adult males are expected to be on shore on 
Guadalupe Island and at smaller rookeries in the San Benito archipelago 
(Carretta et al., 2017b; Norris, 2017b). No satellite telemetry data 
are available for adult males; however, following the breeding season 
most adult males are expected to move north of breeding grounds to 
forage.
    From 2015 through 2017, 26 stranded and rehabilitated fur seals 
between the ages of 11 and 15 months were released with satellite tags 
in central California. These animals frequently migrated north of Point 
Cabrillo and several moved into waters as far north as British 
Columbia, Canada. However, it is unclear if the migratory patterns of 
rehabilitated and released fur seals are representative of the free-
ranging population migrating north from Guadalupe Island. For example, 
the rehabilitated fur seals remained closer to shore than the free-
ranging fur seals as they migrated north (Norris, 2017b).
    The satellite telemetry data indicate that Guadalupe fur seals more 
than two years old are likely uncommon in the survey area, but a 
majority of fur seals under two years old may migrate into the survey 
area and may be present throughout the year (Norris, 2017b). Lambourn 
et al. (2012) described an unusual mortality event during which 29 
Guadalupe fur seals were reported stranded throughout the Pacific 
Northwest from 2007 to 2009. The strandings involved one live adult 
female and 28 dead yearlings of both sexes. The stranding data support 
the more recent telemetry data indicating that fur seals less than 2 
years of age are more likely to occur in the survey area than older fur 
seals.

Northern Elephant Seal

    The northern elephant seal breeds in California and Baja 
California, primarily on offshore islands, from Cedros off the west 
coast of Baja California, north to the Farallons in Central California 
(Stewart et al., 1994). Pupping has also been observed at Shell Island 
(~43.3[deg] N) off southern Oregon, suggesting a range expansion 
(Bonnell et al., 1992; Hodder et al., 1998).
    Adult elephant seals engage in two long northward migrations per 
year, one following the breeding season, and another following the 
annual molt (Stewart and DeLong 1995). Between the two foraging 
periods, they return to land to molt, with females returning earlier 
than males (March-April vs. July-August). After the molt, adults then 
return to their northern feeding areas until the next winter breeding 
season. Breeding occurs from December to March (Stewart and Huber 
1993). Females arrive in late December or January and give birth within 
~1 week of their arrival. Pups are weaned after just 27 days and are 
abandoned by their mothers. Juvenile elephant seals typically leave the 
rookeries in April or May and head north, traveling an average of 900-
1,000 km. Hindell (2009) noted that traveling likely takes place at 
depths >200 m. Most elephant seals return to their natal rookeries when 
they start breeding (Huber et al., 1991).
    When not at their breeding rookeries, adults feed at sea far from 
the rookeries. Males may feed as far north as the eastern Aleutian 
Islands and the Gulf of Alaska, whereas females feed south of 45[deg] N 
(Le Boeuf et al., 1993; Stewart and Huber 1993). Adult male elephant 
seals migrate north via the California current to the Gulf of Alaska 
during foraging trips, and could potentially be passing through the 
area off Washington in May and August (migrating to and from molting 
periods) and November and February (migrating to and from breeding 
periods), but likely their presence there is transient and short-lived. 
Adult females and juveniles forage in the California current off 
California to BC (Le Boeuf et al. 1986, 1993, 2000). Bonnell et al., 
(1992) reported that northern elephant seals were distributed equally 
in shelf, slope, and offshore waters during surveys conducted off 
Oregon and Washington, as far as 150 km from shore, in waters >2,000 m 
deep. Telemetry data indicate that they range much farther offshore 
than that (Stewart and DeLong 1995).

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 whales,  150 Hz to 160 kHz.
 beaked whales, bottlenose whales).
High-frequency (HF) cetaceans (true porpoises, Kogia,    275 Hz to 160 kHz.
 river dolphins, cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).

[[Page 26950]]

 
Phocid pinnipeds (PW) (underwater) (true seals)........  50 Hz to 86 kHz.
Otariid pinnipeds (OW) (underwater) (sea lions and fur   60 Hz to 39 kHz.
 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. 
26 marine mammal species (23 cetacean and three pinniped (two otariid 
and one phocid) species) have the reasonable potential to co-occur with 
the proposed survey activities. Please refer to Table 1. Of the 
cetacean species that may be present, five are classified as low-
frequency cetaceans (i.e., all mysticete species), 15 are classified as 
mid-frequency cetaceans (i.e., all delphinid and ziphiid species and 
the sperm whale), and three 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]Pa2 - 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):
     Wind and waves: The complex interactions between wind and 
water

[[Page 26951]]

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.

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 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.

[[Page 26952]]

    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. 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

[[Page 26953]]

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 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,

[[Page 26954]]

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]Pa2-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.
    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

[[Page 26955]]

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, 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),

[[Page 26956]]

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 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,

[[Page 26957]]

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 4.1 kn (7.6 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% 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.
    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

[[Page 26958]]

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 in\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 (~19 days) at 
two locations and would occur over a very small area relative to the 
area available as marine mammal habitat in the northeast Pacific Ocean 
near the Axial Seamount. We believe any impacts to marine mammals due 
to adverse effects 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-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 these 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

[[Page 26959]]

stock in the wild (Level A harassment); or (ii) has the potential to 
disturb a marine mammal or marine mammal stock in the wild by causing 
disruption of behavioral patterns, including, but not limited to, 
migration, breathing, nursing, breeding, feeding, or sheltering (Level 
B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of seismic airguns has the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory injury (Level A harassment) for mysticetes and 
high frequency cetaceans (i.e., kogiidae spp.), due to larger predicted 
auditory injury zones for those functional hearing groups. The proposed 
mitigation and monitoring measures are expected to minimize the 
severity of such taking to the extent practicable.
    Auditory injury is unlikely to occur for mid-frequency cetaceans, 
otariid pinnipeds, and phocid pinnipeds given very small modeled zones 
of injury for those species (up to 43.7 m). Moreover, the source level 
of the array is a theoretical definition assuming a point source and 
measurement in the far-field of the source (MacGillivray, 2006). As 
described by Caldwell and Dragoset (2000), an array is not a point 
source, but one that spans a small area. In the far-field, individual 
elements in arrays will effectively work as one source because 
individual pressure peaks will have coalesced into one relatively broad 
pulse. The array can then be considered a ``point source.'' For 
distances within the near-field, i.e., approximately 2-3 times the 
array dimensions, pressure peaks from individual elements do not arrive 
simultaneously because the observation point is not equidistant from 
each element. The effect is destructive interference of the outputs of 
each element, so that peak pressures in the near-field will be 
significantly lower than the output of the largest individual element. 
Here, the 230 dB peak isopleth distances would in all cases be expected 
to be within the near-field of the array where the definition of source 
level breaks down. Therefore, actual locations within this distance of 
the array center where the sound level exceeds 230 dB peak SPL would 
not necessarily exist. In general, Caldwell and Dragoset (2000) suggest 
that the near-field for airgun arrays is considered to extend out to 
approximately 250 m.
    In order to provide quantitative support for this theoretical 
argument, we calculated expected maximum distances at which the near-
field would transition to the far-field (Table 5). For a specific array 
one can estimate the distance at which the near-field transitions to 
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN10JN19.001

with the condition that D > l, and where D is the distance, L is the 
longest dimension of the array, and l is the wavelength of the signal 
(Lurton 2002). Given that l can be defined by:
[GRAPHIC] [TIFF OMITTED] TN10JN19.002

where f is the frequency of the sound signal and v is the speed of the 
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN10JN19.003

and calculate D directly given a particular frequency and known speed 
of sound (here assumed to be 1,500 meters per second in water, although 
this varies with environmental conditions).
    To determine the closest distance to the arrays at which the source 
level predictions in Table 1 are valid (i.e., maximum extent of the 
near-field), we calculated D based on an assumed frequency of 1 kHz. A 
frequency of 1 kHz is commonly used in near-field/far-field 
calculations for airgun arrays (Zykov and Carr 2014; MacGillivray 2006; 
NSF and USGS 2011), and based on representative airgun spectrum data 
and field measurements of an airgun array used on the R/V Marcus G. 
Langseth, nearly all (greater than 95 percent) of the energy from 
airgun arrays is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz 
as the upper cut-off for calculating the maximum extent of the near-
field should reasonably represent the near-field extent in field 
conditions.
    If the largest distance to the peak sound pressure level threshold 
was equal to or less than the longest dimension of the array (i.e., 
under the array), or within the near-field, then received levels that 
meet or exceed the threshold in most cases are not expected to occur. 
This is because within the near-field and within the dimensions of the 
array, the source levels specified in Table 1 are overestimated and not 
applicable. In fact, until one reaches a distance of approximately 
three or four times the near-field distance the average intensity of 
sound at any given distance from the array is still less than that 
based on calculations that assume a directional point source (Lurton 
2002). The 6,600 in\3\ airgun array used in the 2D survey has an 
approximate diagonal of 28.8 m, resulting in a near-field distance of 
138.7 m at 1 kHz (NSF and USGS 2011). Field measurements of this array 
indicate that the source behaves like multiple discrete sources, rather 
than a directional point source, beginning at approximately 400 m (deep 
site) to 1 km (shallow site) from the center of the array (Tolstoy et 
al., 2009), distances that are actually greater than four times the 
calculated 140-m near-field distance. Within these distances, the 
recorded received levels were always lower than would be predicted 
based on calculations that assume a directional point source, and 
increasingly so as one moves closer towards the array (Tolstoy et al., 
2009). Similarly, the 3,300 in\3\ airgun array used in the 3D survey 
has an approximate diagonal of 17.9 m, resulting in a near-field 
distance of 53.5 m at 1 kHz (NSF and USGS 2011). Given this, relying on 
the calculated distances (138.7 m for the 2D survey and 53.5 m for the 
3D survey) as the distances at which we expect to be in the near-field 
is a conservative approach since even beyond this distance the acoustic 
modeling still overestimates the actual received level. Within the 
near-field, in order to explicitly evaluate the likelihood of exceeding 
any particular acoustic threshold, one would need to consider the exact 
position of the animal, its relationship to individual array elements, 
and how the individual acoustic sources propagate and their acoustic 
fields interact. Given that within the near-field and dimensions of the 
array source levels would be below those in Table 5, we believe 
exceedance of the peak pressure threshold would only be possible under 
highly unlikely circumstances.
    Therefore, we expect the potential for Level A harassment of mid-
frequency cetaceans, otariid pinnipeds, and phocid pinnipeds to be de 
minimis, even before the likely moderating effects of aversion and/or 
other compensatory behaviors (e.g., Nachtigall et al., 2018) are 
considered. We do not believe that Level A harassment is a likely 
outcome for any mid-frequency cetacean, otariid pinniped, or phocid 
pinniped and do not propose to authorize any Level A harassment for 
these species.
    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

[[Page 26960]]

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.

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

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    The proposed 3D survey would acquire data with the 18-airgun array 
with a total discharge of 3,300 in\3\ towed at a depth of 10 m. The 
proposed 2D survey would acquire data using 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 18-
airgun array, 36-airgun array, and 40-in\3\ airgun 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 (approximately 
1,600 m), intermediate water depth on the slope (approximately 600-
1,100 m), and shallow water (approximately 50 m) in the Gulf of Mexico 
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

[[Page 26961]]

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 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 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 model curve. However, the observed sound levels are found to 
fall almost entirely below the model curve. Thus, analysis of the Gulf 
of Mexico calibration measurements demonstrates that although simple, 
the L-DEO model is a robust tool for conservatively estimating 
isopleths.
    For deep water (>1,000 m), L-DEO used the deep-water radii obtained 
from model results down to a maximum water depth of 2000 m. The radii 
for intermediate water depths (100-1,000 m) were 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 (See Fig. 16 in Appendix H of NSF-USGS, 2011).
    Measurements have not been reported for the single 40-in\3\ airgun. 
L-DEO model results are used to determine the 160-dB (rms) radius for 
the 40-in\3\ airgun at a 12 m tow depth in deep water (See LGL 2018, 
Figure A-2). For intermediate-water depths, a correction factor of 1.5 
was applied to the deep-water model results.
    L-DEO's modeling methodology is described in greater detail in the 
IHA application (LGL 2018). The estimated distances to the Level B 
harassment isopleth for the Langseth's 18-airgun array, 36-airgun 
array, and single 40-in\3\ airgun are shown in Table 4.

Table 4--Predicted Radial Distances From R/V Langseth Seismic Sources to
         Isopleths Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
                                                           Distance (m)
            Source and volume              Tow depth (m)        \a\
------------------------------------------------------------------------
Single Bolt airgun (40 in\3\)...........              12             431
2 strings, 18 airguns (3,300 in\3\).....              10           3,758
4 strings, 36 airguns (6,600 in\3\).....              12           6,733
------------------------------------------------------------------------
\a\ Distance based on L-DEO model results.

    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 2016). 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 far-field 
signature (Table 5). 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.

[[Page 26962]]



 Table 5--Modeled Source Levels Based on Modified Farfield Signature for the R/V Langseth 3,300 in\3\ Airgun Array, 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 dB;  (Lpk,flat: 230 dB;  (Lpk,flat: 202 dB;  (Lpk,flat: 218 dB;  (Lpk,flat: 232 dB;
                                                      LE,LF,24h: 183 dB)  LE,MF,24h: 185 dB)  LE,HF,24h: 155 dB)  LE,HF,24h: 185 dB)  LE,HF,24h: 203 dB)
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
3,300 in\3\ airgun array (Peak SPLflat).............              245.29              250.97              243.61              246.00              251.92
3.300 in\3\ airgun array (SELcum)...................              226.38              226.33              226.66              226.33              227.07
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              232.83              233.08              232.83              232.07
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 
hertz (Hz) bands) was used to make adjustments (dB) to the unweighted 
spectrum levels, by frequency, according to the weighting functions for 
each relevant marine mammal hearing group. These adjusted/weighted 
spectrum levels were then converted to pressures ([mu]Pa) in order to 
integrate them over the entire 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 specific to each 
of the three planned surveys 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 5. User Spreadsheets used by L-DEO to estimate distances 
to Level A harassment isopleths for the 18-airgun array, 36-airgun 
array, and single 40 in\3\ airgun for the surveys are shown in Tables 
A-3, A-6, and A-10 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 6. 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 6--Modeled Radial Distances (m) to Isopleths Corresponding to Level A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                                                      Phocid          Otariid
        Source and volume          LF cetaceans    MF cetaceans    HF cetaceans      pinnipeds       pinnipeds
----------------------------------------------------------------------------------------------------------------
Single Bolt airgun (40 in\3\):
 \a\
    PTS SELcum..................             0.5               0               0               0               0
    PTS Peak....................            1.76            0.51            12.5            1.98             0.4
2 strings, 18 airguns (3300
 in\3\):
    PTS SELcum..................            75.6               0             0.3             2.9               0
    PTS Peak....................            23.2            11.2           118.7            25.1             9.9
4 strings, 36 airguns (6600
 in\3\):
    PTS SELcum..................           426.9               0             1.3            13.9               0
    PTS Peak....................            38.9            13.6           268.3            43.7            10.6
----------------------------------------------------------------------------------------------------------------

    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 developing their IHA application, L-DEO utilized estimates of 
cetacean densities in the survey area synthesized by Barlow (2016). 
Observations from NMFS Southwest Fisheries Science Center (SWFSC) ship 
surveys off of Oregon and Washington (up to 556 km from shore) between 
1991 and 2014 were pooled. Systematic, offshore, at-sea survey data for 
pinnipeds are more limited. To calculate pinniped densities in the 
survey area, L-DEO utilized methods described in U.S. Navy (2010) which 
calculated density estimates for pinnipeds off Washington at different 
times of the year using information on breeding and migration, 
population estimates from shore counts, and areas used by different 
species while at sea. The densities calculated by the Navy were updated 
by L-DEO using stock abundances presented in the latest SARs (e.g., 
Caretta et al., 2018).
    While the IHA application was in review by NMFS, the U.S. Navy 
published the Marine Species Density Database Phase III for the 
Northwest Training and Testing (NWTT) Study

[[Page 26963]]

Area (Navy 2018). The proposed geophysical survey area is located near 
the western boundary of the defined NWTT Offshore Study Area.
    For several cetacean species, the Navy updated densities estimated 
by line-transect surveys or mark-recapture studies (e.g., Barlow 2016). 
These methods usually produce a single value for density that is an 
averaged estimate across very large geographical areas, such as waters 
within the U.S. EEZ off California, Oregon, and Washington (referred to 
as a ``uniform'' density estimate). This is the general approach 
applied in estimating cetacean abundance in the NMFS stock assessment 
reports. The disadvantage of these methods is that they do not provide 
information on varied concentrations of species in sub-regions of very 
large areas, and do not estimate density for other seasons or 
timeframes that were not surveyed. More recently, a newer method called 
spatial habitat modeling has been used to estimate cetacean densities 
that address some of these shortcomings (e.g., Barlow et al., 2009; 
Becker et al., 2010, 2012a, 2014; Becker et al., 2016; Ferguson et al., 
2006; Forney et al., 2012, 2015; Redfern et al., 2006). (Note that 
spatial habitat models are also referred to as ``species distribution 
models'' or ``habitat-based density models.'') These models estimate 
density as a continuous function of habitat variables (e.g., sea 
surface temperature, seafloor depth) and thus, within the study area 
that was modeled, densities can be predicted at all locations where 
these habitat variables can be measured or estimated. Spatial habitat 
models therefore allow estimates of cetacean densities on finer scales 
than traditional line-transect or mark-recapture analyses.
    The methods used to estimate pinniped at-sea densities are 
typically different than those used for cetaceans, because pinnipeds 
are not limited to the water and spend a significant amount of time on 
land (e.g., at rookeries). Pinniped abundance is generally estimated 
via shore counts of animals on land at known haulout sites or by 
counting number of pups weaned at rookeries and applying a correction 
factor to estimate the abundance of the population (for example Harvey 
et al., 1990; Jeffries et al., 2003; Lowry 2002; Sepulveda et al., 
2009). Estimating in-water densities from land-based counts is 
difficult given the variability in foraging ranges, migration, and 
haulout behavior between species and within each species, and is driven 
by factors such as age class, sex class, breeding cycles, and seasonal 
variation. Data such as age class, sex class, and seasonal variation 
are often used in conjunction with abundance estimates from known 
haulout sites to assign an in-water abundance estimate for a given 
area. The total abundance divided by the area of the region provides a 
representative in-water density estimate for each species in a 
different location, which enables analyses of in-water stressors 
resulting from at-sea Navy testing or training activities. In addition 
to using shore counts to estimate pinniped density, traditional line-
transect derived estimates are also used, particularly in open ocean 
areas.
    Because the Navy's density calculations for many species included 
spatial habitat modeling and demographic information, we utilized the 
Navy Marine Species Density Database (NMSDD) to estimate densities and 
resulting take of marine mammals from the proposed geophysical survey. 
Where available, the appropriate seasonal density estimate from the 
NMSDD was used in the estimation here (i.e., summer). For species with 
a quantitative density range within or around the proposed survey area, 
the maximum presented density was conservatively used. Background 
information on the density calculations for each species/guild as well 
as reported sightings in nearby waters are reported here. Density 
estimates for each species/guild are found in Table 7.
Humpback Whale
    NMFS SWFSC developed a CCE habitat-based density model for humpback 
whales which provides spatially explicit density estimates off the U.S. 
West Coast for summer and fall based on survey data collected between 
1991 and 2014 (Becker et al., in prep). Density data are not available 
for the NWTT Offshore area northwest of the SWFSC strata, so the 
habitat-based density values in the northernmost pixels adjoining this 
region were interpolated based on the nearest-neighbor approach to 
provide representative density estimates for this area.
    Six humpback whale sightings (8 animals) were made off Washington/
Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic 
survey; all were well inshore of the proposed survey area (RPS 2012b). 
There were 98 humpback whale sightings (213 animals) made during the 
July 2012 L-DEO seismic survey off southern Washington, northeast of 
the proposed survey area (RPS 2012a), and 11 sightings (23 animals) 
during the July 2012 L-DEO seismic survey off Oregon, southeast of the 
proposed survey area (RPS 2012c). No sightings were made near the 
proposed survey area in the 2014 NMFS Southwest Fisheries Science 
Center (SWFSC) California Current Ecosystem (CCE) vessel survey (Barlow 
2016).
Minke Whale
    Density values for minke whales are available for the SWFSC Oregon/
Washington and Northern California offshore strata for summer/fall 
(Barlow 2016). Density data are not available for the NWTT Offshore 
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates.
    Sightings have been made off Oregon and Washington in shelf and 
deeper waters (Green et al., 1992; Adams et al., 2014; Carretta et al., 
2017). An estimated abundance of 211 minke whales was reported for the 
Oregon/Washington region based on sightings data from 1991-2005 (Barlow 
and Forney 2007), whereas a 2008 survey did not record any minke whales 
while on survey effort (Barlow 2010). The abundance for Oregon/
Washington for 2014 was estimated at 507 minke whales (Barlow 2016). 
There were no sightings of minke whales off Washington/Oregon during 
the June-July 2012 L-DEO Juan de Fuca plate seismic survey or during 
the July 2012 L-DEO seismic survey off Oregon, southeast of the 
proposed survey area (RPS 2012b, c). One minke whale was seen during 
the July 2012 L-DEO seismic survey off southern Washington, north of 
the proposed survey area (RPS 2012a). No sightings of minke whales were 
made near the proposed survey area during the 2014 SWFSC CCE vessel 
survey (Barlow 2016).
Sei Whale
    Density values for sei whales are available for the SWFSC Oregon/
Washington and Northern California offshore strata for summer/fall 
(Barlow 2016). Density data are not available for the NWTT Offshore 
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates.
    Sei whales are rare in the waters off California, Oregon, and 
Washington (Brueggeman et al., 1990; Green et al., 1992; Barlow 1994, 
1997). Only 16 confirmed sightings were reported for California, 
Oregon, and Washington during extensive surveys from 1991-2014 (Green 
et al., 1992, 1993; Hill and Barlow 1992; Carretta and Forney 1993; 
Mangels and Gerrodette 1994; Von Saunder and Barlow 1999; Barlow 2003; 
Forney 2007; Barlow 2010; Carretta et al., 2017). Based on surveys 
conducted in 1991-2008, the estimated abundance

[[Page 26964]]

of sei whales off the coasts of Oregon and Washington was 52 (Barlow 
2010); for 2014, the abundance estimate was 468 (Barlow 2016). Two 
sightings of four individuals were made during the June-July 2012 L-DEO 
Juan de Fuca plate seismic survey off Washington/Oregon (RPS 2012b); 
these were well inshore of the proposed survey area (~125[deg] W). No 
sei whales were sighted during the July 2012 L-DEO seismic surveys 
north and south of the proposed survey area (RPS 2012a, c).
Fin Whale
    NMFS SWFSC developed a CCE habitat-based density model for fin 
whales which provides spatially explicit density estimates off the U.S. 
West Coast for summer and fall based on survey data collected between 
1991 and 2014 (Becker et al., in prep). Density data are not available 
for the NWTT Offshore area northwest of the SWFSC strata, so the 
habitat-based density values in the northernmost pixels adjoining this 
region were interpolated based on the nearest-neighbor approach to 
provide representative density estimates for this area.
    Fin whales are routinely sighted during surveys off Oregon and 
Washington (Barlow and Forney 2007; Barlow 2010; Adams et al., 2014; 
Calambokidis et al., 2015; Edwards et al., 2015; Carretta et al., 
2017), including in coastal as well as offshore waters. They have also 
been detected acoustically near the proposed study area during June-
August (Edwards et al., 2015). There is one sighting of a fin whale in 
the Ocean Biogeographic Information System (OBIS) database within the 
proposed survey area, which was made in August 2005 during the SWFSC 
Collaborative Survey of Cetacean Abundance and the Pelagic Ecosystem 
(CSCAPE) Marine Mammal Survey, and several other sightings in adjacent 
waters (OBIS 2018). Eight fin whale sightings (19 animals) were made 
off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca 
plate seismic survey, including two sightings (4 animals) in the 
vicinity of the proposed survey area; sightings were made in waters 
2,369-3,940 m deep (RPS 2012b). Fourteen fin whale sightings (28 
animals) were made during the July 2012 L-DEO seismic surveys off 
southern Washington, northeast of the proposed survey area (RPS 2012a). 
No fin whales were sighted during the July 2012 L-DEO seismic survey 
off Oregon, southeast of the proposed survey area (RPS 2012c). Fin 
whales were also seen off southern Oregon during July 2012 in water 
>2,000 m deep during surveys by Adams et al. (2014).
Blue Whale
    NMFS SWFSC developed a CCE habitat-based density model for blue 
whales which provides spatially explicit density estimates off the U.S. 
West Coast for summer and fall based on survey data collected between 
1991 and 2014 (Becker et al., in prep). Density data are not available 
for the NWTT Offshore area northwest of the SWFSC strata, so the 
habitat-based density values in the northernmost pixels adjoining this 
region were interpolated based on the nearest-neighbor approach to 
provide representative density estimates for this area.
    The nearest sighting of blue whales is ~55 km to the southwest 
(OBIS 2018), and there are several other sightings in adjacent waters 
(Carretta et al., 2018; OBIS 2018). Satellite telemetry suggests that 
blue whales are present in waters offshore of Oregon and Washington 
during fall and winter (Bailey et al., 2009; Hazen et al., 2017).
Sperm Whale
    NMFS SWFSC developed a CCE habitat-based density model for sperm 
whales which provides spatially explicit density estimates off the U.S. 
West Coast for summer and fall based on survey data collected between 
1991 and 2014 (Becker et al., in prep). Density data are not available 
for the NWTT Offshore area northwest of the SWFSC strata, so the 
habitat-based density values in the northernmost pixels adjoining this 
region were interpolated based on the nearest-neighbor approach to 
provide representative density estimates for this area.
    There is one sighting of a sperm whale in the vicinity of the 
survey area in the OBIS database that was made in July 1996 during the 
SWFSC ORCAWALE Marine Mammal Survey (OBIS 2018), and several other 
sightings in adjacent waters (Carretta et al., 2018; OBIS 2018). Sperm 
whale sightings were also made in the vicinity of the proposed survey 
area during the 2014 SWFSC vessel survey (Barlow 2016). A single sperm 
whale was sighted during the 2009 ETOMO survey, north of the proposed 
survey area (Holst 2017). Sperm whales were detected acoustically in 
waters near the proposed survey area in August 2016 during the SWFSC 
Passive Acoustics Survey of Cetacean Abundance Levels (PASCAL) study 
using drifting acoustic recorders (Keating et al., 2018).
Pygmy and Dwarf Sperm Whales (Kogia Guild)
    Kogia species are treated as a guild off the U.S. West Coast 
(Barlow & Forney 2007). Barlow (2016) provided stratified density 
estimates for Kogia spp. for waters off California, Oregon, and 
Washington; these were used for all seasons for both the Northern 
California and Oregon/Washington strata. In the absence of other data, 
the Barlow (2016) Oregon/Washington estimate was also used for the area 
northwest of the SWFSC strata for all seasons.
    Pygmy and dwarf sperm whales are rarely sighted off Oregon and 
Washington, with only one sighting of an unidentified Kogia sp. beyond 
the U.S. EEZ, during the 1991-2014 NOAA vessel surveys (Carretta et 
al., 2017). This sighting was made in October 1993 during the SWFSC 
PODS Marine Mammal Survey ~150 km to the south of the proposed survey 
area (OBIS 2018). Norman et al. (2004) reported eight confirmed 
stranding records of pygmy sperm whales for Oregon and Washington, five 
of which occurred during autumn and winter.
Baird's Beaked Whale
    NMFS SWFSC developed a CCE habitat-based density model for Baird's 
beaked whale which provides spatially explicit density estimates off 
the U.S. West Coast for summer and fall based on survey data collected 
between 1991 and 2014 (Becker et al., in prep). Density data are not 
available for the NWTT Offshore area northwest of the SWFSC strata, so 
the habitat-based density values in the northernmost pixels adjoining 
this region were interpolated based on the nearest-neighbor approach to 
provide representative density estimates for this area.
    Green et al. (1992) sighted five groups during 75,050 km of aerial 
survey effort in 1989-1990 off Washington/Oregon spanning coastal to 
offshore waters: Two in slope waters and three in offshore waters. Two 
groups were sighted during summer/fall 2008 surveys off Washington/
Oregon, in waters >2,000 m deep (Barlow 2010). Acoustic monitoring 
offshore Washington detected Baird's beaked whale pulses during January 
through November 2011, with peaks in February and July 
([Scirc]irovi[cacute] et al., 2012b in USN 2015). Baird's beaked whales 
were detected acoustically near the proposed survey area in August 2016 
during the SWFSC PASCAL study using drifting acoustic recorders 
(Keating et al., 2018). There is one sighting of a Baird's beaked whale 
near the survey area in the OBIS database that was made in August 2005 
during the SWFSC CSCAPE Marine Mammal Survey (OBIS 2018).

[[Page 26965]]

Small Beaked Whale Guild
    NMFS has developed habitat-based density models for a small beaked 
whale guild in the CCE (Becker et al., 2012b; Forney et al., 2012). The 
small beaked whale guild includes Cuvier's beaked whale and beaked 
whales of the genus Mesoplodon, including Blainville's beaked whale, 
Hubbs' beaked whale, and Stejneger's beaked whale. NMFS SWFSC developed 
a CCE habitat-based density model for the small beaked whale guild 
which provides spatially explicit density estimates off the U.S. West 
Coast for summer and fall based on survey data collected between 1991 
and 2014 (Becker et al., in prep). Density data are not available for 
the NWTT Offshore area northwest of the SWFSC strata, so the habitat-
based density values in the northernmost pixels adjoining this region 
were interpolated based on the nearest-neighbor approach to provide 
representative density estimates for this area.
    Four beaked whale sightings were reported in water depths >2,000 m 
off Oregon/Washington during surveys in 2008 (Barlow 2010). None were 
seen in 1996 or 2001 (Barlow 2003), and several were recorded from 1991 
to 1995 (Barlow 1997). One Cuvier's beaked whale sighting was made east 
of the proposed survey area during 2014 (Barlow 2016). Acoustic 
monitoring in Washington offshore waters detected Cuvier's beaked whale 
pulses between January and November 2011 ([Scirc]irovi[cacute] et al., 
2012b in USN 2015). There is one sighting of a Cuvier's beaked whale 
near the proposed survey area in the OBIS database that was made in 
July 1996 during the SWFSC ORCAWALE Marine Mammal Survey (OBIS 2018), 
and several other sightings were made in adjacent waters, primarily to 
the south and east of the proposed survey area (Carretta et al., 2018; 
OBIS 2018). Cuvier's beaked whales were detected acoustically in waters 
near the proposed survey area in August 2016 during the SWFSC PASCAL 
study using drifting acoustic recorders (Keating et al., 2018).
    There are no sightings of Blainville's beaked whales near the 
proposed survey area in the OBIS database (OBIS 2018). There is one 
sighting of an unidentified species of Mesoplodont whale near the 
survey area in the OBIS database that was made in July 1996 during the 
SWFSC ORCAWALE Marine Mammal Survey (OBIS 2018). There was one acoustic 
encounter with Blainville's beaked whales recorded in Quinault Canyon 
off Washington in waters 1,400 m deep during 2011 (Baumann-Pickering et 
al., 2014). Blainville's beaked whales were not detected acoustically 
in waters near the proposed survey area in August 2016 during the SWFSC 
PASCAL study using drifting acoustic recorders (Keating et al., 2018). 
Although Blainville's beaked whales could be encountered during the 
proposed survey, an encounter would be unlikely because the proposed 
survey area is beyond the northern limits of this tropical species' 
usual distribution.
    Stejneger's beaked whale calls were detected during acoustic 
monitoring offshore Washington between January and June 2011, with an 
absence of calls from mid-July to November 2011 ([Scirc]irovi[cacute] 
et al., 2012b in USN 2015). Analysis of these data suggest that this 
species could be more than twice as prevalent in this area than Baird's 
beaked whale (Baumann-Pickering et al., 2014). Stejneger's beaked 
whales were also detected acoustically in waters near the proposed 
survey area in August 2016 during the SWFSC PASCAL study using drifting 
acoustic recorders (Keating et al., 2018). There are no sightings of 
Stejneger's beaked whales near the proposed survey area in the OBIS 
database (OBIS 2018). There is one sighting of an unidentified species 
of Mesoplodont beaked whale near the survey area in the OBIS database 
that was made during July 1996 during the SWFSC ORCAWALE Marine Mammal 
Survey (OBIS 2018).
    Baird's beaked whale is sometimes seen close to shore where deep 
water approaches the coast, but its primary habitat is over or near the 
continental slope and oceanic seamounts (Jefferson et al., 2015). Along 
the U.S. West Coast, Baird's beaked whales have been sighted primarily 
along the continental slope (Green et al., 1992; Becker et al., 2012; 
Carretta et al., 2018) from late spring to early fall (Green et al., 
1992). The whales move out from those areas in winter (Reyes 1991). In 
the eastern North Pacific Ocean, Baird's beaked whales apparently spend 
the winter and spring far offshore, and in June, they move onto the 
continental slope, where peak numbers occur during September and 
October. Green et al. (1992) noted that Baird's beaked whales on the 
U.S. West Coast were most abundant in the summer, and were not sighted 
in the fall or winter. MacLeod et al. (2006) reported numerous 
sightings and strandings of Berardius spp. off the U.S. West Coast.
Bottlenose Dolphin
    During surveys off the U.S. West Coast, offshore bottlenose 
dolphins were generally found at distances greater than 1.86 miles (3 
km) from the coast and were most abundant off southern California 
(Barlow 2010, 2016). Based on sighting data collected by SWFSC during 
systematic surveys in the Northeast Pacific between 1986 and 2005, 
there were few sightings of offshore bottlenose dolphins north of about 
40[deg] N (Hamilton et al., 2009). NMFS SWFSC developed a CCE habitat-
based density model for bottlenose dolphins which provides spatially 
explicit density estimates off the U.S. West Coast for summer and fall 
based on survey data collected between 1991 and 2014 (Becker et al., in 
prep). Density data are not available for the NWTT Offshore area 
northwest of the SWFSC strata, so the habitat-based density values in 
the northernmost pixels adjoining this region were interpolated based 
on the nearest-neighbor approach to provide representative density 
estimates for this area.
    Bottlenose dolphins occur frequently off the coast of California, 
and sightings have been made as far north as 41[deg] N, but few records 
exist for Oregon/Washington (Carretta et al., 2017). Three sightings 
and one stranding of bottlenose dolphins have been documented in Puget 
Sound since 2004 (Cascadia Research 2011 in USN 2015). It is possible 
that offshore bottlenose dolphins may range as far north as the 
proposed survey area during warm-water periods (Carretta et al., 2017). 
Adams et al. (2014) made one sighting off Washington during September 
2012. There are no sightings of bottlenose dolphins near the proposed 
survey area in the OBIS database (OBIS 2018).
Striped Dolphin
    Striped dolphin encounters increase in deep, relatively warmer 
waters off the U.S. West Coast, and their abundance decreases north of 
about 42[deg] N (Barlow et al., 2009; Becker et al., 2012b; Becker et 
al., 2016; Forney et al., 2012). Although striped dolphins typically do 
not occur north of California, there are a few sighting records off 
Oregon and Washington (Barlow 2003, 2010; Von Saunder & Barlow 1999), 
and multiple sightings in 2014 when water temperatures were anomalously 
warm (Barlow 2016). NMFS SWFSC developed a CCE habitat-based density 
model for striped dolphins which provides spatially explicit density 
estimates off the U.S. West Coast for summer and fall based on survey 
data collected between 1991 and 2014 (Becker et al., in prep). Density 
data are not available for the NWTT Offshore area northwest of the 
SWFSC strata, so the habitat-based density values in the northernmost 
pixels adjoining this region were interpolated based on the

[[Page 26966]]

nearest-neighbor approach to provide representative density estimates 
for this area.
    Striped dolphins regularly occur off California (Becker et al., 
2012), where they have been seen as far as the ~300 n.mi. limit during 
the NOAA Fisheries vessel surveys (Carretta et al., 2017). Strandings 
have occurred along the coasts of Oregon and Washington (Carretta et 
al., 2016). During surveys off the U.S. West Coast in 2014, striped 
dolphins were seen as far north as 44[deg] N (Barlow 2016).
Short-Beaked Common Dolphin
    Short-beaked common dolphins are found off the U.S. West Coast 
throughout the year, distributed between the coast and at least 345 
miles (556 km) from shore (Barlow 2010; Becker et al., 2017; Carretta 
et al., 2017b). The short-beaked common dolphin is the most abundant 
cetacean species off California (Barlow 2016; Carretta et al., 2017b; 
Forney et al., 1995); however, their abudance decreases dramatically 
north of about 40[deg] N (Barlow et al., 2009; Becker et al., 2012c; 
Becker et al., 2016; Forney et al., 2012). Short-beaked common dolphins 
are occasionally sighted in waters off Oregon and Washington, and one 
group of approximately 40 short-beaked common dolphins was sighted off 
northern Washington in 2005 at about 48[deg] N (Forney 2007), and 
multiple groups were sighted as far north as 44[deg] N during 
anomalously warm conditions in 2014 (Barlow 2016). NMFS SWFSC developed 
a CCE habitat-based density model for short-beaked common dolphins 
which provides spatially explicit density estimates off the U.S. West 
Coast for summer and fall based on survey data collected between 1991 
and 2014 (Becker et al., in prep). Density data are not available for 
the NWTT Offshore area northwest of the SWFSC strata, so the habitat-
based density values in the northernmost pixels adjoining this region 
were interpolated based on the nearest-neighbor approach to provide 
representative density estimates for this area.
    There are no sightings of short-beaked dolphins near the proposed 
survey area in the OBIS database (OBIS 2018).
Pacific White-Sided Dolphin
    Pacific white-sided dolphins occur year-round in the offshore 
region of the NWTT Study Area, with increased abundance in the summer/
fall (Barlow 2010; Forney & Barlow 1998; Oleson et al., 2009). NMFS 
SWFSC developed a CCE habitat-based density model for Pacific white-
sided dolphins which provides spatially explicit density estimates off 
the U.S. West Coast for summer and fall based on survey data collected 
between 1991 and 2014 (Becker et al., in prep). Density data are not 
available for the NWTT Offshore area northwest of the SWFSC strata, so 
the habitat-based density values in the northernmost pixels adjoining 
this region were interpolated based on the nearest-neighbor approach to 
provide representative density estimates for this area.
    Fifteen Pacific white-sided dolphin sightings (231 animals) were 
made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca 
plate seismic survey; none were near the proposed survey area (RPS 
2012b). There were fifteen Pacific white-sided dolphin sightings (462 
animals) made during the July 2012 L-DEO seismic surveys off southern 
Washington, northeast of the proposed survey area (RPS 2012a). This 
species was not sighted during the July 2012 L-DEO seismic survey off 
Oregon, southeast of the proposed survey area (RPS 2012c). One group of 
10 Pacific white-sided dolphins was sighted during the 2009 ETOMO 
survey north of the proposed survey area (Holst 2017).
Northern Right Whale Dolphin
    Survey data suggest that, at least in the eastern North Pacific, 
seasonal inshore-offshore and north-south movements are related to prey 
availability, with peak abundance in the Southern California Bight 
during winter and distribution shifting northward into Oregon and 
Washington as water temperatures increase during late spring and summer 
(Barlow 1995; Becker et al., 2014; Forney et al., 1995; Forney & Barlow 
1998; Leatherwood & Walker 1979). NMFS SWFSC developed a CCE habitat-
based density model for northern right whale dolphins which provides 
spatially explicit density estimates off the U.S. West Coast for summer 
and fall based on survey data collected between 1991 and 2014 (Becker 
et al., in prep). Density data are not available for the NWTT Offshore 
area northwest of the SWFSC strata, so the habitat-based density values 
in the northernmost pixels adjoining this region were interpolated 
based on the nearest-neighbor approach to provide representative 
density estimates for this area.
    Seven northern right whale dolphin sightings (231 animals) were 
made off Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca 
plate seismic survey; none were seen near the proposed survey area (RPS 
2012b). There were eight northern right whale dolphin sightings (278 
animals) made during the July 2012 L-DEO seismic surveys off southern 
Washington, northeast of the proposed survey area (RPS 2012a). This 
species was not sighted during the July 2012 L-DEO seismic survey off 
Oregon, southeast of the proposed survey area (RPS 2012c).
Risso's Dolphin
    NMFS SWFSC developed a CCE habitat-based density model for Risso's 
dolphins which provides spatially explicit density estimates off the 
U.S. West Coast for summer and fall based on survey data collected 
between 1991 and 2014 (Becker et al., in prep). Density data are not 
available for the NWTT Offshore area northwest of the SWFSC strata, so 
the habitat-based density values in the northernmost pixels adjoining 
this region were interpolated based on the nearest-neighbor approach to 
provide representative density estimates for this area.
    Two sightings of 38 individuals were recorded off Washington from 
August 2004 to September 2008 (Oleson et al., 2009). Risso's dolphins 
were sighted off Oregon, in June and October 2011 (Adams et al., 2014). 
There were three Risso's dolphin sightings (31 animals) made during the 
July 2012 L-DEO seismic surveys off southern Washington, northeast of 
the proposed survey area (RPS 2012a). This species was not sighted 
during the July 2012 L-DEO seismic survey off Oregon, southeast of the 
proposed survey area (RPS 2012c), or off Washington/Oregon during the 
June-July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b).
False Killer Whale
    False killer whales were not included in the NMSDD, as they are 
very rarely encountered in the northeast Pacific. Density estimates for 
false killer whales were also not presented in Barlow (2016), as no 
sightings occurred during surveys conducted between 1986 and 2008 
(Ferguson and Barlow 2001, 2003; Forney 2007; Barlow 2003, 2010). One 
sighting was made off of southern California during 2014 (Barlow 2016). 
There are no sightings of false killer whales near the survey area in 
the OBIS database (OBIS 2018).
Killer Whale
    Due to the difficulties associated with reliably distinguishing the 
different stocks of killer whales from at-sea sightings, density 
estimates for the Offshore region of the NWTT Study Area are presented 
for the species as a whole (i.e., includes the Offshore, West

[[Page 26967]]

Coast Transient, Northern Resident, and Southern Resident stocks). 
Density values for killer whales are available for the SWFSC Oregon/
Washington and Northern California offshore strata for summer/fall 
(Barlow 2016). Density data are not available for the NWTT Offshore 
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates. These values 
were used to represent density year-round.
    Eleven sightings of ~536 individuals were reported off Oregon/
Washington during the 2008 SWFSC vessel survey (Barlow 2010). Killer 
whales were sighted offshore Washington during surveys from August 2004 
to September 2008 (Oleson et al., 2009). Keating et al. (2015) analyzed 
cetacean whistles from recordings made during 2000-2012; several killer 
whale acoustic detections were made offshore Washington.
Short-Finned Pilot Whale
    Along the U.S. West Coast, short-finned pilot whales were once 
common south of Point Conception, California (Carretta et al., 2017b; 
Reilly & Shane 1986), but now sightings off the U.S. West Coast are 
infrequent and typically occur during warm water years (Carretta et 
al., 2017b). Stranding records for this species from Oregon and 
Washington waters are considered to be beyond the normal range of this 
species rather than an extension of its range (Norman et al., 2004). 
Density values for short-finned pilot whales are available for the 
SWFSC Oregon/Washington and Northern California strata for summer/fall 
(Barlow 2016). Density data are not available for the NWTT Offshore 
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates. These values 
were used to represent density year-round.
    Few sightings were made off California/Oregon/Washington in 1984-
1992 (Green et al., 1992; Carretta and Forney 1993; Barlow 1997), and 
sightings remain rare (Barlow 1997; Buchanan et al., 2001; Barlow 
2010). No short-finned pilot whales were seen during surveys off Oregon 
and Washington in 1989-1990, 1992, 1996, and 2001 (Barlow 2003). A few 
sightings were made off California during surveys in 1991-2014 (Barlow 
2010). Carretta et al. (2017) reported one sighting off Oregon during 
1991-2008. Several stranding events in Oregon/southern Washington have 
been recorded over the past few decades, including in March 1996, June 
1998, and August 2002 (Norman et al., 2004).
Dall's Porpoise
    NMFS SWFSC developed a CCE habitat-based density model for Dall's 
porpoise which provides spatially explicit density estimates off the 
U.S. West Coast for summer and fall based on survey data collected 
between 1991 and 2014 (Becker et al., in prep). Density data are not 
available for the NWTT Offshore area northwest of the SWFSC strata, so 
the habitat-based density values in the northernmost pixels adjoining 
this region were interpolated based on the nearest-neighbor approach to 
provide representative density estimates for this area.
    Oleson et al. (2009) reported 44 sightings of 206 individuals off 
Washington during surveys form August 2004 to September 2008. Dall's 
porpoise were seen in the waters off Oregon during summer, fall, and 
winter surveys in 2011 and 2012 (Adams et al., 2014). Nineteen Dall's 
porpoise sightings (144 animals) were made off Washington/Oregon during 
the June-July 2012 L-DEO Juan de Fuca plate seismic survey; none were 
in near the proposed survey area (RPS 2012b). There were 16 Dall's 
porpoise sightings (54 animals) made during the July 2012 L-DEO seismic 
surveys off southern Washington, northeast of the proposed survey area 
(RPS 2012a). This species was not sighted during the July 2012 L-DEO 
seismic survey off Oregon, southeast of the proposed survey area (RPS 
2012c). Dall's porpoise was the most frequently sighted marine mammal 
species (5 sightings of 28 animals) during the 2009 ETOMO survey north 
of the proposed survey area (Holst 2017).
Northern Fur Seal
    The Navy estimated the abundance of northern fur seals from the 
Eastern Pacific stock and the California breeding stock that could 
occur in the NWTT Offshore Study Area by determining the percentage of 
time tagged animals spent within the Study Area and applying that 
percentage to the population to calculate an abundance for adult 
females, juveniles, and pups independently on a monthly basis. Adult 
males are not expected to occur within the Offshore Study Area and the 
proposed survey area during the proposed geophysical survey as they 
spend the summer ashore at breeding areas in the Bering Sea and San 
Miguel Island (Caretta et al., 2017b). Using the monthly abundances of 
fur seals within the Offshore Study Area, the Navy created strata to 
estimate the density of fur seals within three strata: 22 km to 70 km 
from shore, 70 km to 130 km from shore, and 130 km to 463 km from shore 
(the western Study Area boundary). L-DEO's proposed survey is 423 km 
from shore at the closest point. Based on satellite tag data and 
historic sealing records (Olesiuk 2012; Kajimura 1984), the Navy 
assumed 25 percent of the population present within the overall 
Offshore Study Area may be within the 130 km to 463 km stratum.
    Thirty-one northern fur seal sightings (63 animals) were made off 
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate 
seismic survey north of the proposed survey area (RPS 2012b). There 
were six sightings (6 animals) made during the July 2012 L-DEO seismic 
surveys off southern Washington, northeast of the proposed survey area 
(RPS 2012a). This species was not sighted during the July 2012 L-DEO 
seismic survey off Oregon, southeast of the proposed survey area (RPS 
2012c).
Guadalupe Fur Seal
    As with northern fur seals, adult male Guadalupe fur seals are 
expected to be ashore at breeding areas over the summer, and are not 
expected to be present during the proposed geophysical survey (Caretta 
et al., 2017b; Norris 2017b). Additionally, breeding females are 
unlikely to be present within the Offshore Study Area as they remain 
ashore to nurse their pups through the fall and winter, making only 
short foraging trips from rookeries (Gallo-Reynoso et al., 2008; Norris 
2017b; Yochem et al., 1987). To estimate the total abundance of 
Guadalupe fur seals, the Navy adjusted the population reported in the 
2016 SAR (Caretta et al., 2017b) of 20,000 seals by applying the 
average annual growth rate of 7.64 percent over the seven years between 
2010 and 2017. The resulting 2017 projected abundance was 33,485 fur 
seals. Using the reported composition of the breeding population of 
Guadalupe fur seals (Gallo-Reynoso 1994) and satellite telemetry data 
(Norris 2017b), the Navy established seasonal and demographic 
abundances of fur seals expected to occur within the Offshore Study 
Area.
    The distribution of Guadalupe fur seals in the Offshore Study Area 
was stratified by distance from shore (or water depth) to reflect their 
preferred pelagic habitat (Norris 2017a). Ten percent of fur seals in 
the Study Area are expected to use waters over the continental shelf 
(approximated as waters with depths between 10 and 200 m). A depth of 
10 m is used as the shoreward extent of the shelf (rather than 
extending to shore), because Guadalupe fur seals in the Offshore

[[Page 26968]]

Study Area are not expected to haul out and would not be likely to come 
close to shore. All fur seals (i.e., 100 percent) would use waters off 
the shelf (beyond the 200 m isobath) out to 300 km from shore, and 25 
of percent of fur seals would be expected to use waters between 300 and 
700 km from shore (including the proposed geophysical survey area). The 
second stratum (200 m to 300 km from shore) is the preferred habitat 
where Guadalupe fur seals are most likely to occur most of the time. 
Individuals may spend a portion of their time over the continental 
shelf or farther than 300 km from shore, necessitating a density 
estimate for those areas, but all Guadalupe fur seals would be expected 
to be in the central stratum most of the time, which is the reason 100 
percent is used in the density estimate for the central stratum (Norris 
2017a). Spatial areas for the three strata were estimated in a GIS and 
used to calculate the densities.
    Guadalupe fur seals have not previously been observed in the 
proposed survey area, nor on previous L-DEO surveys off Washington and 
Oregon.
Northern Elephant Seal
    The most recent surveys supporting the abundance estimate for 
northern elephant seals were conducted in 2010 (Caretta et al., 2017b). 
By applying the average growth rate of 3.8 percent per year for the 
California breeding stock over the seven years from 2010 to 2017, the 
Navy calculated a projected 2017 abundance estimate of 232,399 elephant 
seals (Caretta et al., 2017b; Lowry et al., 2014). Male and female 
distributions at sea differ both seasonally and spatially. Pup counts 
reported by Lowry et al. (2014) and life tables compiled by Condit et 
al. (2014) were used to determine the proportion of males and females 
in the population, which was estimated to be 56 percent female and 44 
percent male. Females are assumed to be at sea 100 percent of the time 
within their seasonal distribution area in fall and summer (Robinson et 
al., 2012). Males are at sea approximately 90 percent of the time in 
fall and spring, remain ashore through the entire winter, and spend one 
month ashore to molt in the summer (i.e., are at sea 66 percent of the 
summer). Monthly distribution maps produced by Robinson et al. (2012) 
showing the extent of foraging areas used by satellite tagged female 
elephant seals were used to estimate the spatial areas to calculate 
densities. Although the distributions were based on tagged female 
seals, Le Boeuf et al. (2000) and Simmons et al. (2007) reported 
similar tracks by males over broad spatial scales. The spatial areas 
representing each monthly distribution were calculating using GIS and 
then averaged to produce seasonally variable areas and resulting 
densities.
    Off Washington, most elephant seal sightings at sea were made 
during June, July, and September; off Oregon, sightings were recorded 
from November through May (Bonnell et al. 1992). Several seals were 
seen off Oregon during summer, fall, and winter surveys in 2011 and 
2012 (Adams et al. 2014). Northern elephant seals were also taken as 
bycatch off Oregon in the west coast groundfish fishery during 2002-
2009 (Jannot et al. 2011). Northern elephant seals were sighted five 
times (5 animals) during the July 2012 L-DEO seismic surveys off 
southern Washington, northeast of the proposed survey area (RPS 2012a). 
This species was not sighted during the July 2012 L-DEO seismic survey 
off Oregon, southeast of the proposed survey area (RPS 2012c), or off 
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate 
seismic survey that included the proposed survey area (RPS 2012b). One 
northern elephant seal was sighted during the 2009 ETOMO survey north 
of the proposed survey area (Holst 2017).

    Table 7--Marine Mammal Density Values in the Proposed Survey Area
------------------------------------------------------------------------
                                                               Reported
                           Species                            density (#/
                                                              km\2\) \a\
------------------------------------------------------------------------
LF Cetaceans:
  Humpback whale............................................    0.001829
  Minke whale...............................................      0.0013
  Sei whale.................................................      0.0004
  Fin whale.................................................    0.004249
  Blue whale................................................    0.001096
MF Cetaceans:
  Sperm whale...............................................    0.002561
  Cuvier's and Mesoplodont beaked whales....................    0.007304
  Baird's beaked whale......................................     0.00082
  Bottlenose dolphin........................................    0.000003
  Striped dolphin...........................................    0.009329
  Short-beaked common dolphin...............................    0.124891
  Pacific white-sided dolphin...............................    0.017426
  Northern right-whale dolphin..............................    0.039962
  Risso's dolphin...........................................    0.007008
  False killer whale........................................         N/A
  Killer whale..............................................         \b\
                                                                 0.00092
  Short-finned pilot whale..................................     0.00025
HF Cetaceans:
  Kogia spp.................................................     0.00163
  Dall's porpoise...........................................    0.043951
Otariids:
  Northern fur seal.........................................  \b\ 0.0103
  Guadalupe fur seal........................................      0.0029
Phocids:
  Northern elephant seal....................................      0.0309
------------------------------------------------------------------------
\a\ Navy 2018.
\b\ No stock-specific densities are available so densities are presumed
  equal for all stocks present.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. In order to estimate 
the number of marine mammals predicted to be exposed to sound levels 
that would result in Level A or Level B harassment, radial distances 
from the airgun array to predicted isopleths corresponding to the Level 
A harassment and Level B harassment thresholds are calculated, as 
described above. Those radial distances are then used to calculate the 
area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the Level A and Level B harassment thresholds. The 
area estimated to be ensonified in a single day of the survey is then 
calculated (Table 8), based on the areas predicted to be ensonified 
around the array and representative trackline distances traveled per 
day. This number is then multiplied by the number of survey days. 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 and Level B harassment 
thresholds.

                         Table 8--Areas (km\2\) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds, per Day
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                               Daily                                           Total
                  Survey                              Criteria               Relevant       ensonified     Total survey    25% increase     ensonified
                                                                           isopleth (m)    area (km\2\)        days                        area (km\2\)
--------------------------------------------------------------------------------------------------------------------------------------------------------
2-D Survey................................                                               Level B Harassment
                                           -------------------------------------------------------------------------------------------------------------

[[Page 26969]]

 
                                            160-dB......................           6,733        1,346.90               3            1.25        5,050.86
                                           -------------------------------------------------------------------------------------------------------------
                                                                                         Level A Harassment
                                           -------------------------------------------------------------------------------------------------------------
                                            LF Cetaceans................           426.9          158.67               3            1.25          595.01
                                            HF Cetaceans................           268.3           99.77               3            1.25          374.12
                                            Phocids.....................            43.7           16.26               3            1.25           60.96
                                            MF Cetaceans................            13.6            5.06               3            1.25           18.97
                                            Otariids....................            10.6            3.94               3            1.25           14.79
--------------------------------------------------------------------------------------------------------------------------------------------------------
3-D Survey                                                                               Level B Harassment
                                           -------------------------------------------------------------------------------------------------------------
                                            160-dB......................           3,758          690.52              16            1.25       13,810.40
                                           -------------------------------------------------------------------------------------------------------------
                                                                                         Level A Harassment
                                           -------------------------------------------------------------------------------------------------------------
                                            LF Cetaceans................           118.7           47.39              16            1.25          947.74
                                            HF Cetaceans................            75.6           30.13              16            1.25          602.59
                                            Phocids.....................            25.1            9.98              16            1.25          199.59
                                            MF Cetaceans................            11.2            4.45              16            1.25           89.01
                                            Otariids....................             9.9            3.93              16            1.25           78.67
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The marine mammals predicted to occur within these respective 
areas, based on estimated densities, are assumed to be incidentally 
taken. For species where take by Level A harassment has been requested, 
the calculated Level A takes have been subtracted from the total 
exposures within the Level B harassment zone. Estimated exposures for 
the proposed survey are shown in Table 9.

                Table 9--Estimated Level A and Level B Exposures, and Percentage of Stock Exposed
----------------------------------------------------------------------------------------------------------------
                                                                                                    Percent of
            Species                   Stock           Level B         Level A       Total take         stock
----------------------------------------------------------------------------------------------------------------
                                                  LF Cetaceans
----------------------------------------------------------------------------------------------------------------
Humpback whale................  California/                   32               3              35            1.21
                                 Oregon/
                                 Washington.
Minke whale...................  California/                   23               2              25            3.93
                                 Oregon/
                                 Washington.
Sei whale.....................  Eastern North                  7               1               8            1.54
                                 Pacific.
Fin whale.....................  California/                   74               7              81            0.90
                                 Oregon/
                                 Washington.
Blue whale....................  Eastern North                 19               2              21            1.28
                                 Pacific.
----------------------------------------------------------------------------------------------------------------
                                                  MF Cetaceans
----------------------------------------------------------------------------------------------------------------
Sperm whale...................  California/                   48               0              48            2.40
                                 Oregon/
                                 Washington.
Cuvier's and Mesoplodont        California/                  138               0             138        \a\ 2.18
 beaked whales.                  Oregon/
                                 Washington.
Baird's beaked whale..........  California/                   15               0              15            0.56
                                 Oregon/
                                 Washington.
Bottlenose dolphin............  California/               \b\ 13               0          \b\ 13            0.68
                                 Oregon/
                                 Washington.
Striped dolphin...............  California/                  176               0             176            0.60
                                 Oregon/
                                 Washington.
Short-beaked common dolphin...  California/                2,356               0           2,356            0.24
                                 Oregon/
                                 Washington.
Pacific white-sided dolphin...  California/                  329               0             329            1.23
                                 Oregon/
                                 Washington.
Northern right-whale dolphin..  California/                  754               0             749            2.82
                                 Oregon/
                                 Washington.
Risso's dolphin...............  California/                  132               0             132            2.08
                                 Oregon/
                                 Washington.
False killer whale............  Hawaii Pelagic..           \b\ 5               0           \b\ 5            0.32
Killer whale..................  Offshore........              17               0              17        \c\ 5.67
                                West Coast        ..............  ..............  ..............        \c\ 7.00
                                 Transient.
Short-finned pilot whale......  California/               \b\ 18               0          \b\ 18            2.15
                                 Oregon/
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                                  HF Cetaceans
----------------------------------------------------------------------------------------------------------------
Kogia spp.....................  California/                   31               2              29            0.71
                                 Oregon/
                                 Washington.
Dall's porpoise...............  California/                  829              43             786            3.05
                                 Oregon/
                                 Washington.
----------------------------------------------------------------------------------------------------------------
                                                    Otariids
----------------------------------------------------------------------------------------------------------------
Northern fur seal.............  Eastern Pacific.             194               0             194        \c\ 0.03
                                California......  ..............  ..............  ..............        \c\ 1.38

[[Page 26970]]

 
Guadalupe fur seal............  Mexico..........              55               0              55            0.28
----------------------------------------------------------------------------------------------------------------
                                                     Phocids
----------------------------------------------------------------------------------------------------------------
Northern elephant seal........  California                   583               0             583            0.33
                                 Breeding.
----------------------------------------------------------------------------------------------------------------
\a\ Combined stock abundances for Cuvier's beaked whales and Mesoplodont guild.
\b\ Calculated take increased to mean group size (Barlow 2016).
\c\ Where multiple stocks are affected, for the purposes of calculating the percentage of stock affected, takes
  are analyzed as if all takes occurred within each stock.

    It should be noted that the proposed take numbers shown in Table 9 
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 due to the different density estimates used, and in 
consideration of the near-field soundscape of the airgun array, 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).

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 (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting 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. 
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; and (7) Vessel strike 
avoidance 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 meter 
exclusion zone, out to a radius of 1,000 meters from the edges of the 
airgun array (500-1,000 meters). 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 
exclusion zone by alerting the visual observer and crew of marine 
mammals

[[Page 26971]]

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 acoustic source (i.e., 
anytime airguns are 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.
    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) should 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 Exclusion and Buffer Zones

    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

[[Page 26972]]

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 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.

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; and
     Testing of the acoustic source involving all elements 
requires ramp-up. Testing limited to individual source elements or 
strings does not require ramp-up but does require pre-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 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

[[Page 26973]]

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, pygmy sperm, dwarf sperm, and 
beaked 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--
Tursiops, Delphinus, Lagenodelphis, Lagenorhynchus, Lissodelphis, 
Stenella and Steno--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 delphinoid exception because power-down/
shutdown requirements for small delphinoids under all circumstances 
represent practicability concerns without likely commensurate benefits 
for the animals in question. Small delphinoids 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 delphinoids 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinoids (e.g., Barkaszi et al., 2012). The potential for 
increased shutdowns resulting from such a measure would require the 
Langseth to revisit the missed track line to reacquire data, resulting 
in an overall increase in the total sound energy input to the marine 
environment and an increase in the total duration over which the survey 
is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large delphinoids) are no more likely to incur 
auditory injury than are small delphinoids, they are much less likely 
to approach vessels. Therefore, retaining a power-down/shutdown 
requirement for large delphinoids 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 delphinoids 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; and
    5. When marine mammals are sighted while a vessel is underway, the 
vessel 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

[[Page 26974]]

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.

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 five 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:
     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:

[[Page 26975]]

     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); and
     Any additional information recorded such as water depth of 
the hydrophone array, bearing of the animal to the vessel (if 
determinable), species or taxonomic group (if determinable), 
spectrogram screenshot, and any other notable information.

Reporting

    A report would be submitted to NMFS within 90 days after the end of 
the cruise. The report would 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 and including an estimate of those 
that were not detected, in consideration of both the characteristics 
and behaviors of the species of marine mammals that affect 
detectability, as well as the environmental factors that affect 
detectability.
    L-DEO will be required to 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 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.

Reporting Injured or Dead Marine Mammals

    In the event that personnel involved in survey activities covered 
by the authorization discover an injured or dead marine mammal, the L-
DEO shall report the incident to the Office of Protected Resources 
(OPR), NMFS and to the NMFS West Coast Regional Stranding Coordinator 
as soon as feasible. The report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);

[[Page 26976]]

     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.
    Additional Information Requests--If NMFS determines that the 
circumstances of any marine mammal stranding found in the vicinity of 
the activity suggest investigation of the association with survey 
activities is warranted (example circumstances noted below), and an 
investigation into the stranding is being pursued, NMFS will submit a 
written request to the IHA-holder indicating that the following initial 
available information must be provided as soon as possible, but no 
later than 7 business days after the request for information.
     Status of all sound source use in the 48 hours preceding 
the estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
     If available, description of the behavior of any marine 
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and 
immediately after the discovery of the stranding.
    Examples of circumstances that could trigger the additional 
information request include, but are not limited to, the following:
     Atypical nearshore milling events of live cetaceans;
     Mass strandings of cetaceans (two or more individuals, not 
including cow/calf pairs);
     Beaked whale strandings;
     Necropsies with findings of pathologies that are unusual 
for the species or area; or
     Stranded animals with findings consistent with blast 
trauma.
    In the event that the investigation is still inconclusive, the 
investigation of the association of the survey activities is still 
warranted, and the investigation is still being pursued, NMFS may 
provide additional information requests, in writing, regarding the 
nature and location of survey operations prior to the time period 
above.
    Vessel Strike--In the event of a ship strike of a marine mammal by 
any vessel involved in the activities covered by the authorization, L-
DEO must shall report the incident to OPR, NMFS and to regional 
stranding coordinators as soon as feasible. The report must include the 
following information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Species identification (if known) or description of the 
animal(s) involved;
     Vessel's speed during and leading up to the incident;
     Vessel's course/heading and what operations were being 
conducted (if applicable);
     Status of all sound sources in use;
     Description of avoidance measures/requirements that were 
in place at the time of the strike and what additional measures were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
     Estimated size and length of animal that was struck;
     Description of the behavior of the marine mammal 
immediately preceding and following the strike;
     If available, description of the presence and behavior of 
any other marine mammals immediately preceding the strike;
     Estimated fate of the animal (e.g., dead, injured but 
alive, injured and moving, blood or tissue observed in the water, 
status unknown, disappeared); and
     To the extent practicable, photographs or video footage of 
the animal(s).

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 
Tables 7 and 9, given that NMFS expects the anticipated effects of the 
proposed geophysical survey to be similar in nature. Where there are 
meaningful differences between species or stocks, or groups of species, 
in anticipated individual responses to activities, impact of expected 
take on the population due to differences in population status, or 
impacts on habitat, NMFS has identified species-specific factors to 
inform the analysis.
    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 
harassment of seven species and Level B harassment of 26 marine mammal 
species. 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 that are considered to be of low severity 
and with no lasting biological consequences (e.g., Southall et al., 
2007). The proposed geophysical survey occurs outside of the U.S. EEZ 
and outside of

[[Page 26977]]

any established Biologically Important Areas or critical habitat.
    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 
(~19 days) and temporary nature of the disturbance, the availability of 
similar habitat and resources in the surrounding area, the impacts to 
marine mammals and the food sources that they utilize are not expected 
to cause significant or long-term consequences for individual marine 
mammals or their populations.
    The activity is expected to impact a small percentage of all marine 
mammal stocks that would be affected by L-DEO's proposed survey (less 
than seven percent of all species). 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 some extent of potential PTS in marine 
mammals that may otherwise occur in the absence of the proposed 
mitigation.
    The ESA-listed marine mammal species under our jurisdiction that 
are likely to be taken by the proposed surveys include the endangered 
sei, fin, blue, sperm, and Central America DPS humpback whales, and the 
threatened Mexico DPS humpback whale and Guadalupe fur seal. We propose 
to authorize very small numbers of takes for these species relative to 
their population sizes. Given the low probability of fitness impacts to 
any individual, combined with the small portion of any of these stocks 
impacted, we do not expect population-level impacts to any of these 
species. The other marine mammal species that may be taken by 
harassment during the proposed survey are not listed as threatened or 
endangered under the ESA. With the exception of the northern fur seal, 
none of the non-listed marine mammals for which we propose to authorize 
take are considered ``depleted'' or ``strategic'' by NMFS under the 
MMPA.
    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 (19 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 PTS that may occur are expected 
to be very small in number. Instances of 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; and
     The proposed mitigation measures, including visual and 
acoustic monitoring, power-downs, and shutdowns, are expected to 
minimize potential impacts to marine mammals.
    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 Sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. Additionally, other qualitative 
factors may be considered in the analysis, such as the temporal or 
spatial scale of the activities.
    Table 9 provides the numbers of take by Level A and Level B 
harassment proposed for authorization, which are used herefor purposes 
of the small numbers analysis. The numbers of marine mammals that we 
propose for authorized take would be considered small relative to the 
relevant populations (less than seven percent for all species and 
stocks) for the species for which abundance estimates are available.
    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

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
preliminarily determined that the total taking of affected species or 
stocks would not have an unmitigable adverse impact on the availability 
of such species or stocks for taking for subsistence purposes.

[[Page 26978]]

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 sei whales, fin whales, blue 
whales, sperm whales, Central America DPS humpback whales, Mexico DPS 
humpback whales and Guadalupe fur seals which are listed under the ESA. 
The Permit 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 a marine geophysical survey in the 
northeast Pacific Ocean in 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); and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
     Upon review of the request for renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: June 3, 2019.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2019-12010 Filed 6-7-19; 8:45 am]
 BILLING CODE 3510-22-P