[Federal Register Volume 87, Number 120 (Thursday, June 23, 2022)]
[Notices]
[Pages 37560-37598]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-13328]



[[Page 37559]]

Vol. 87

Thursday,

No. 120

June 23, 2022

Part II





 Department of Commerce





-----------------------------------------------------------------------





 National Oceanic and Atmospheric Administration





Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to Marine Geophysical Surveys at the Cascadia 
Subduction Zone and Juan de Fuca Plate in the Northeast Pacific Ocean; 
Notice

  Federal Register / Vol. 87, No. 120 / Thursday, June 23, 2022 / 
Notices  

[[Page 37560]]


-----------------------------------------------------------------------

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XC041]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Marine Geophysical Surveys at the 
Cascadia Subduction Zone and Juan de Fuca Plate 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.

-----------------------------------------------------------------------

SUMMARY: NMFS has received a request from Lamont-Doherty Earth 
Observatory (L-DEO) for authorization to take marine mammals incidental 
to geophysical surveys at the Cascadia Subduction Zone and Juan de Fuca 
Plate 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-time, one-year renewal that could be issued 
under certain circumstances and if all requirements are met, as 
described in Request for Public Comments at the end of this notice. 
NMFS will consider public comments prior to making any final decision 
on the issuance of the requested MMPA authorization and agency 
responses will be summarized in the final notice of our decision.

DATES: Comments and information must be received no later than July 25, 
2022.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be submitted via email 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, including all attachments, must 
not exceed a 25-megabyte file size. All comments received are a part of 
the public record and will generally be posted online at 
www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.

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

SUPPLEMENTARY INFORMATION:

Background

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

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or 
mortality) of the Companion Manual for NOAA Administrative Order 216-
6A, which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has 
preliminarily determined that the issuance of the proposed IHA 
qualifies to be categorically excluded from further NEPA review.

Summary of Request

    On December 14, 2021, NMFS received a request from L-DEO for an IHA 
to take marine mammals incidental to a marine geophysical survey off 
the coasts of Oregon and Washington in the northeast Pacific Ocean. The 
application was deemed adequate and complete on April 4, 2022. L-DEO 
request is for take of small numbers of 23 species of marine mammals by 
Level B harassment only. Neither L-DEO nor NMFS expects serious injury 
or mortality to result from this activity and, therefore, an IHA is 
appropriate.
    NMFS previously issued an IHA to L-DEO for larger surveys in a 
similar location in the Northeast Pacific (e.g., 86 FR 29090; May 28, 
2021; 84 FR 35073; July 22, 2019). These surveys, however, included 
survey areas much closer to the coast. L-DEO complied with all the 
requirements (e.g., mitigation, monitoring, and reporting) of the 
previous IHAs and information regarding their monitoring results may be 
found in the Description of Marine Mammals in the Area of Specified 
Activities section.

Description of Proposed Activity

Overview

    Researchers from New Mexico Institute of Mining and Technology 
(NMT) and Oregon State University (OSU), with funding from the U.S. 
National Science Foundation (NSF) propose to conduct low-energy seismic 
surveys from the Research Vessel (R/V) Marcus G. Langseth (Langseth), 
which is owned and operated by Lamont-Doherty Earth Observatory (L-DEO) 
of Columbia University, at the Cascadia subduction Zone and Juan de 
Fuca Plate in the

[[Page 37561]]

Northeast Pacific Ocean during Summer 2022. The proposed two-
dimensional (2-D) seismic surveys would occur within the Exclusive 
Economic Zone (EEZ) of the United States, in waters deeper than 1600 
meters (m). To complete this survey, the R/V Langseth would tow a 
Generator-Injector (GI)-airgun cluster consisting of two 45 cubic inch 
(in\3\) GI guns spaced 2.46 m apart, with a total discharge volume of 
90 in\3\. The acoustic source would be towed at 2 to 4 m deep along the 
survey lines, while the receiving system is towed in an 800-1400 m long 
hydrophone streamer.
    The proposed study would acquire high-resolution 2-D seismic 
reflection data in conjunction with densely-spaced heat flow 
measurements to better understand the thermal structure of the Juan de 
Fuca plate as it enters the Cascadia subduction zone. The seismic and 
heat flow data would be acquired across several distinct structures 
that have not been previously studied, including a pseudofault, complex 
buried seamounts, and small outcrops that represent the summit of much 
larger buried seamounts.

Dates and Duration

    The proposed survey is expect to last for 23 days, with 
approximately six days of seismic operations, three days of transit and 
14 days of heat flow measurements. R/V Langseth would likely leave out 
of and return to port in Newport, OR, during summer 2022.

Specific Geographic Region

    The proposed survey would occur within ~42-47[deg]N, ~125-127[deg]W 
off the coast of Washington and Oregon in the Northeast Pacific ocean. 
Four regions where the surveys are proposed to occur are depicted in 
Figure 1; the tracklines could occur anywhere within the boxes shown in 
Figure 1. No representative survey tracklines are shown, as actual 
track lines and order of survey operations are dependent on science 
objectives and weather. The surveys are proposed to occur within the 
EEZ of the U.S., in waters >1600 m deep.
BILLING CODE 3510-22-P

[[Page 37562]]

[GRAPHIC] [TIFF OMITTED] TN23JN22.000

BILLING CODE 3510-22-C

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 and operated by L-DEO. R/V 
Langseth would deploy two 45/105 in\3\ GI airguns as an energy source 
with a total volume of ~90 in\3\. The receiving system would consist of 
one 800-1400 m long hydrophone streamer. As the airguns are towed along 
the survey lines, the hydrophone streamer would transfer data to the 
on-board processing system. Approximately 1135 kilometers (km) of 
transect lines would be surveyed in four survey regions in the 
Northeast Pacific Ocean; 200 km, 95 km, 440 km, and 400 km in the 
Coast, Nubbin, Pseudofault, and Oregon survey regions, respectively. 
All survey effort would occur in deep water >1600 m. In addition to the 
operations of the airgun array, the ocean floor would be mapped with 
the Kongsberg EM 122 multibeam echosounder (MBES), a Knudsen CHIRP

[[Page 37563]]

3260 (SBP) and an Acoustic Doppler Current Profiler (ADCP) would be 
operated from the vessel continuously. 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. 
Take of marine mammals is not expected to occur incidental to use of 
the MBES, SBP and ADCP, whether or not the airguns are operating 
simultaneously with the other sources. Given their characteristics 
(e.g., narrow downward-directed beam), marine mammals would experience 
no more than one or two brief ping exposures, if any exposure were to 
occur. NMFS does not expect that the use of these sources presents any 
reasonable potential to cause take of marine mammals.
    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. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, incorporated here by reference, instead of 
reprinting the information. Additional information regarding population 
trends and threats may be found in NMFS' Stock Assessment Reports 
(SARs; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these 
species (e.g., physical and behavioral descriptions) may be found on 
NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all species or stocks for which take is expected and 
proposed to be authorized for this action, and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. 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' 
SARs). While no serious injury or 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 
comprise 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 SARs (Carretta et al., 2021). All values presented 
in Table 1 are the most recent available at the time of publication and 
are available in the 2020 SARs (Carretta et al., 2021) and draft 2021 
SARs (available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports).

                                              Table 1--Species Likely Impacted by the Specified Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                         ESA/MMPA
                                                                          status;        Stock abundance (CV, Nmin, most recent                Annual M/
          Common name             Scientific name         Stock          strategic               abundance survey) \2\                 PBR       SI \3\
                                                                         (Y/N) \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenopteridae
 (rorquals):
    Humpback whale.............  Megaptera          California/Oregon/ -,-,Y                             4,973 (0.05, 4,776, 2018)       28.7      >48.6
                                  novaeangliae.      Washington.
    Minke whale................  Balaenoptera       California/Oregon/ -,-,N                                915 (0.792, 509, 2018)        4.1      >0.59
                                  acutorostrata.     Washington.
    Sei whale..................  Balaenoptera       Eastern North      E, D, Y                                519 (0.4, 374, 2014)       0.75       >0.2
                                  borealis.          Pacific.
    Fin whale..................  Balaenoptera       California/Oregon/ E, D, Y                         11,065 (0.405, 7,970, 2018)         80       >2.2
                                  physalus.          Washington.
    Blue whale.................  Balaenoptera       Eastern North      E, D, Y                          1,898 (0.085, 1,767, 2018)        4.1      >19.4
                                  musculus.          Pacific.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale................  Physeter           California/Oregon/ E, D, Y                            1,997 (0.57, 1270, 2014)        2.5        0.6
                                  macrocephalus.     Washington.
Family Kogiidae:
    Pygmy sperm whale..........  Kogia breviceps..  California/Oregon/ -,-,N                              4,111 (1.12, 1924, 2014)         19          0
                                                     Washington.
    Dwarf sperm whale..........  Kogia sima.......  California/Oregon/ -,-,N                                  UNK (UNK, UNK, 2014)        UND          0
                                                     Washington.
Family Ziphiidae (beaked
 whales):
    Baird's beaked whale.......  Berardius Bairdii  California/Oregon/ -,-,N                               1,363 (0.53, 894, 2018)        8.9       >0.2
                                                     Washington.
    Cuvier's beaked whale......  Ziphius            California/Oregon/ -,-,N                             3,274 (0.67, 2,059, 2014)         21       <0.1
                                  cavirostris.       Washington.
    Mesoplodont Beaked Whales..  Mesoplodon spp...  California/Oregon/ -,-,N                             3,044 (0.54, 1,967, 2005)         20        0.1
                                                     Washington.
Family Delphinidae:
    Striped dolphin............  Stenella           California/Oregon/ -,-,N                            29,988 (0.3, 23,448, 2018)        225         >4
                                  coeruleoalba.      Washington.
    Short-beaked common dolphin  Delphinus delphis  California/Oregon/ -,-,N                       1,056,308 (0.21, 888,971, 2018)      8,889      >30.5
                                                     Washington.

[[Page 37564]]

 
    Pacific white-sided dolphin  Lagenorhynchus     California/Oregon/ -,-,C                          34,998 (0.222, 29,090, 2018)        279          7
                                  obliquidens.       Washington.
    Northern right whale         Lissodelphis       California/Oregon/ -,-,N                            29,285 (0.72, 17024, 2018)        163       >6.6
     dolphin.                     borealis.          Washington.
    Risso's dolphin............  Grampus griseus..  California/Oregon/ -,-,N                             6,336 (0.32, 4,817, 2014)         46       >3.7
                                                     Washington.
    Killer whale...............  Orcinus orca.....  West Coast         -,-,N                                  349 (N/A, 349, 2018)        3.5        0.4
                                                     Transient.
                                                    North Pacific      -,-,N                                  300 (0.1, 276, 2012)        2.8          0
                                                     Offshore.
Family Phocoenidae (porpoises):
    Dall's porpoise............  Phocoenoides       California/Oregon/ -,-,N                           16,498 (0.61, 10,286, 2019)         99      >0.66
                                  dalli.             Washington.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals
 and sea lions):
    Northern fur seal..........  Callorhinus        Eastern Pacific..  -,D,Y                          626,618 (0.2, 530,376, 2020)     11,403        373
                                  ursinus.
                                                    California.......  -,D,Y                             14,050 (N/A, 7,524, 2013)        451        1.8
    Guadalupe fur seal.........  Arctocephalus      Mexico...........  T, D, Y                          34,187 (N/A, 31,019, 2013)      1,062       >3.8
                                  townsendi.
    Steller sea lion...........  Eumetopias         Eastern..........  -,-,N                             43,201 (N/A, 43,201,2017)      2,592        112
                                  jubatus.
    California sea lion........  Zalophus           United States....  -,-,N                          257,606 (N/A, 233,525, 2014)     14,011       >320
                                  californianus.
Family Phocidae (earless
 seals):
    Northern elephant seal.....  Mirounga           California         -,-,N                           187,386 (N/A, 85,369, 2013)      5,122        5.3
                                  angustirostris.    Breeding.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports. 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.

    As indicated above, all 23 species (with 25 managed stocks) in 
Table 1 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur. While North Pacific 
right whales (Eubalaena japonica), bottlenose dolphins (Tursiops 
truncatus), short-finned pilot whales (Globicephala macrorhynchus), 
gray whales (Eschrichtius robustus), and false killer whales (Pseudorca 
crassidens) have been documented near the area, the temporal and/or 
spatial occurrence of these species is such that take is not expected 
to occur. Therefore, they are not discussed further beyond the 
explanation provided below.
    The North Pacific right whale is one of the rarest marine mammals 
in the world (Muto et al., 2021). The species comprises of an eastern 
and western population that are largely or wholly discrete. The summer 
range of the eastern stock includes the Gulf of Alaska and the Bergin 
Sea, while the western stock is believed to feed in the Okhotsk Sea and 
in pelagic waters of the northwestern North Pacific (Muto et al., 
2021). Whaling records from the 19th century and recent Soviet catch 
data have shown that right whales were broadly distributed across the 
eastern North Pacific (Scarff 1986, Brownell et al., 2001, Ivashchenko 
and Clapham 2012). There are sporadic records from below 20 degrees 
north, but the bulk of the data show right whales concentrated north of 
35 degrees north, including coastal and offshore waters ranging from 
Washington state and British Columbia through the Gulf of Alaska, 
Alaska Peninsula, Aleutian Islands, and the Bering Sea (Muto et al., 
2021).
    The eastern North Pacific stock that occurs in the United States is 
estimated to contain 31 whales for the Bering sea and Aleutian Islands. 
A Biologically Important Area (BIA) for feeding for North Pacific right 
whales was designated east of the Kodiak Archipelago, which includes 
the Gulf of Alaska critical habitat and extends south of 56 degrees 
north and north of 58 degrees north and beyond the shelf edge. South of 
50 degrees north, only 29 reliable sightings were recorded from 1900-
1994 (Scarff 1986, 1991; Carretta et al.,1994). Off the coast of 
California/Oregon/Washington, only seven documented sightings of right 
whales were made from 1990 through 2000. Two North Pacific right whale 
calls were detected on a bottom-mounted hydrophone (located in water 
1390 m deep) off the Washington coast on June 29, 2013 (Sirovic et al., 
2014). During L-DEO's summer 2021 seismic survey in the Northeast 
Pacific, a sighting of two individuals was made northwest of the survey 
area in British Columbia, west of Haida Gwaii on July 27, 2021. Because 
of the small population size, and the fact that North Pacific right 
whales spend the summer feeding in high latitudes, the likelihood that 
the proposed survey would encounter a North Pacific right whale is 
discountable, and NMFS is not proposing to authorize take of this 
species.
    Bottlenose dolphins are distributed worldwide in tropical and warm-
temperate waters. Bottlenose dolphins occur frequently off the coast of 
California, and sightings have been made as far north as 41 degrees 
north, but few records exist for Oregon and Washington (Carretta et 
al., 2021). In California, separate coastal and offshore populations 
are known (Walker 1981; Ross and Cockcroft 1999; Van Waerebeek et al., 
1990; Lowther 2006). Three sightings and one stranding of bottlenose 
dolphins have been documented in Puget Sound since 2004 (Cascadia 
Research 2011 in U.S.C.

[[Page 37565]]

2015). L-DEO requested authorization for the incidental take of 
bottlenose dolphins (the request was for a total of 13 individuals). 
Although sightings of bottlenose dolphins in Puget Sound have increased 
considerably since 2016 (Cascadia Research Collective, 2020), given the 
far north and offshore placement of the proposed survey and the 
species' tendency to stay in coastal waters and in lower latitudes, we 
believe it is highly unlikely that bottlenose dolphins would be 
encountered in the proposed survey area, and NMFS is not proposing to 
authorize take of this species.
    Short-finned pilot whales are found in tropical and warm temperate 
waters (Olson 2018) and seen as far south as 40 degrees south and as 
far north as 50 degrees north (Jefferson et al., 2015). Pilot whales 
are generally nomadic, but may reside in certain locations, including 
California and Hawaii (Olson 2018). The species were common off 
southern California (Dohl et al., 1980) until an El Nino event occurred 
in 1982-1983 (Green et al., 1992; Carretta and Forney 1993; Barlow 
1997). Few sightings were made off California/Oregon/Washington in 
1983-1984, but 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 
(Barolow 2003). Only one sighting has occurred off Oregon from 1991-
2014 (Carretta et al., 2021). Although zero Level B harassment exposure 
estimates were calculated, L-DEO requested authorization for the 
incidental take of 29 short-finned pilot whales based on the average 
group size produced by Barlow (2016). However, considering the species' 
historical occurrence in the proposed survey area, their preference for 
warmer tropical waters, and the best available information, the 
likelihood that L-DEO will encounter short-finned pilot whales in the 
proposed survey area is discountable, and NMFS is not proposing to 
authorize take of this species.
    Two separate populations of gray whales have been recognized in the 
North Pacific: the eastern North Pacific and western North Pacific 
stocks (LeDuc et al., 2002; Weller et al., 2013). However, the 
distinction between these two populations has been recently debated 
owing to evidence that whales from the western feeding area also travel 
to breeding areas in the eastern North Pacific (Weller et al., 2012, 
2013; Mate et al., 2015). BIAs for feeding gray whales along the coasts 
of Washington, Oregon, and California have been identified, including 
northern Puget sound, Northwestern Washington, and Grays Harbor (WA); 
Depoe Bay and Cape Blanco and Orford Reef (OR), and Point St. George 
(CA); most of these areas are of importance from late spring through 
early fall (Calambokidis et al., 2015); none occur within the proposed 
survey region. Resident gray whales have been observed foraging off the 
coast of Oregon from May through October and off Washington June 
through November (Newell and Cowles 2006; Scordino et al., 2014). BIAs 
have also been identified for migrating gray whales along the entire 
coasts of Washington, Oregon, and California; although most whales 
travel within 10 km from shore, the BIAs were extended out to 47 km 
from the coastline (Calambokidis et al., 2015); the proposed Oregon 
survey region is located adjacent to this BIA (see Figure 1). Gray 
whales from the far north begin to migrate south to breeding grounds on 
the west coast of Baja California and the southeastern Gulf of 
California in October and November (Braham 1984; Rugh et al., 2001). 
Gray whales migrate closest to the Washington/Oregon coastline during 
spring (April-June), when most strandings are observed (Norman et al., 
2004). The species' stock range extends from as far south as Mexico all 
the way north to the Gulf of Alaska, primarily hugging the coastline 
(NMFS 2022).
    NOAA (2021b) declared an unusual mortality event (UME) for gray 
whales in 2019, as an elevated number of strandings have occurred along 
the coast of the Pacific Northwest since January 2019. As of 1 October 
2021, a total of 212 dead gray whales have been reported, including 248 
in the U.S. (55 in Washington; 12 in Oregon), 225 in Mexico, and 19 in 
B.C.; some of the whales were emaciated. A UME for gray whales was also 
declared for 1999-2000 (NOAA 2021c).
    The proposed survey is planned during the summer feeding season, 
when most individuals from the eastern North Pacific stock occur 
farther north. Although individuals, particularly from the Pacific 
Coast Feeding Group (PCFG), could be encountered in nearshore waters 
less than 10 km from shore, the likelihood that any gray whales will be 
encountered as far offshore as the proposed survey area is 
discountable. Gray whales have been observed to have a distinct 
ecological niche in nearshore and shallow waters (Darling et al., 1998) 
and L-DEO's proposed activities to not overlap with this niche. L-DEO 
requested the incidental take of a singular gray whale, however NMFS 
does not propose to authorize any take of gray whales as it is 
temporally and spatially unlikely that they will be encountered.
    Lastly, the false killer whale is found worldwide in tropical and 
temperate waters, generally between 50 degrees north and 50 degrees 
south (Odell and McClune 1999). It is widely distributed, but not 
abundant anywhere (Carwardine 1995). The false killer whale generally 
inhabits deep, offshore waters, but sometimes is found over the 
continental shelf and occasionally moves into very shallow water 
(Jefferson et al., 2015; Baird 2018b). In the eastern North Pacific, it 
has been reported only rarely north of Baja California (Leatherwood et 
al., 1982, 1987; Mangels and Gerrodete 1994); however, the waters off 
the United States 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). However, no sightings of false 
killer whales were made along the U.S. west coast during surveys 
conducted from 1986-2001 (Ferguson and Barlow 2001, 2003; Barlow 2003) 
or in 2005 and 2008 (Forney 2007; Barlow 2010). One pod of false killer 
whales occurred in Puget Sound for several months during the 1990s (USN 
2015). Two false killer whales were reported stranded along the 
Washington coast during 1930-2002, both in El Ni[ntilde]o years (Norman 
et al., 2004). Based on the best available information, NMFS believes 
that the likelihood of the survey encountering a false killer whale is 
discountable and, although L-DEO requested incidental take of 5 whales 
based on their average group size (Mobley et al., 2000), NMFS does not 
propose authorizing any take of false killer whales.

Humpback Whale

    The humpback whale is found throughout all of the oceans of the 
world (Clapham 2009). The worldwide population 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., Jackson et al,. 2014; Bettriddge et al,. 2015). Although 
considered to be mainly a coastal species, humpback whales often 
traverse deep pelagic areas while migrating (Calambokidis et al., 2001; 
Garrigue et al., 2002; Zerbini et al., 2011). Humpbacks migrate between 
summer feeding grounds in high latitudes and winter calving and 
breeding grounds in tropical waters (Clapham and Mead 1999). Northern 
Pacific humpback whales summer in

[[Page 37566]]

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; Bettridge et al., 2015). 
Humpbacks in the north Pacific 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).
    Prior to 2016, humpback whales were listed under the ESA as an 
endangered species worldwide. Following a 2015 global status review 
(Bettridge et al., 2015), NMFS established 14 distinct population 
segments (DPS) with different listing statuses (81 FR 62259); September 
8, 20216) pursuant to the ESA. The DPSs that occur in United States 
waters do not necessarily equate to the existing stocks designated 
under the MMPA and shown in Table 1. Because the MMPA stocks cannot be 
portioned (i.e,. parts managed as ESA-listed while other parts managed 
as non-ESA listed), until such time as the MMPA stock delineations are 
reviewed in light of the DPS designations, NMFS considers the existing 
humpback whale stocks under the MMPA to be endangered and depleted for 
MMPA management purposes (e.g., selection of a recovery factor, stock 
status).
    NMFS has identified three DPSs of humpback whales that are found 
off the coasts of Washington, Oregon and California. These are: the 
Hawaii DPS (found predominately off Washington and southern British 
Columbia), which is not listed under the ESA; the Mexico DPS (found all 
along the west coast), which is listed as threatened under the ESA; and 
the Central America DPS (found all along the west coast, but most 
common off California and Oregon), which is listed as endangered under 
the ESA. According to Wade (2021), the probability that whales 
encountered in Oregon and California waters are from a given DPS are as 
follows: Central America DPS (42 percent); Mexico DPS (58 percent); 
Hawaii DPS (0 percent). The probability that humpback whales 
encountered in Washington and British Columbia waters are as follows: 
Central America DPS (6 percent); Mexico DPS (25 percent); Hawaii DPS 
(69 percent). Wade (2021) notes that the majority of humpback whales 
that may be found off of Washington are likely moving north of the 
United States border and feeding primarily off of southern British 
Columbia.
    Humpback whales are 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). Humpbacks occur 
primarily over the continental shelf and slope during the summer, but a 
few individuals have been reported in offshore pelagic waters (Green et 
al., 1992; Calambokidis et al., 2004, 2015; Becker et al., 2012; Barlow 
2016; Carretta et al., 2021). Biologically Important Areas (BIAs) for 
feeding humpback whales along the coasts of Oregon and Washington, 
which have been designated from May through November, are all within 
approximately 80 kilometers (km) from shore, and include the waters off 
northern Washington, and Stonewall and Heceta Bank, OR (Calambokidis et 
al., 2015). Six humpback whale sightings (eight animals) were made off 
Washington and Oregon during the June through July 2012 L-DEO Juan de 
Fuca plate seismic survey. There were 98 humpback whale sightings (213 
animals) made during the July 2012 L-DEO seismic survey off Oregon (RPS 
2012a), and 11 sightings (23 animals) during the July 2012 L-DEO 
seismic survey off Oregon (RPS 2012c). Numerous humpback whale 
sightings were made during L-DEO's Cascadia summer survey off Oregon 
and Washington in 2021 (RPS).
    On April 21, 2021, NMFS designated critical habitat in nearshore 
waters of the North Pacific Ocean for the endangered Central America 
and Western North Pacific DPSs and the threatened Mexico DPS of 
humpback whales (NMFS 2021). Critical habitat for the Central America 
and Mexico DPSs include waters within the California Current Ecosystem 
(CCE) off the coasts of California, Oregon, and Washington (Figure 1). 
Off Washington, critical habitat includes waters from the 50 m to 1200 
m isobaths, as well as the strait of Juan de Fuca eastward to Angeles 
Point; however, there is an exclusion area of 1461 nautical square 
miles (nmi\2\) around the Navy's Quinault Range Site. Off Oregon, the 
critical habitat spans from the 50 m to 1200 m isobath until 42.17 
degrees north where the critical habitat south of 42.17 degrees north 
extends out to the 2000 m isobath (NMFS 2021). There is no critical 
habitat designated within the proposed survey regions, and ensonified 
areas would not extend into critical habitat. Humpback whales are 
expected to be uncommon in the proposed offshore survey areas.

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 whales 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., 2000; Stafford 2003) 
suggest that there are two separate populations: one in eastern and one 
in the western North Pacific (Sears and Perrin 2018). The status of 
these two populations could differ substantially, as little is known 
about the population size in the western North Pacific (Branch et al., 
2016). Broad scale acoustic monitoring indicate 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 prevalent, 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 
through November (Calambokidis et al.,1990; Mate et al., 2015), and 
core areas have also been identified.
    Blue whales are considered rare off Oregon, Washington, and B.C. 
(Buchanan et al. 2001; Gregr et al., 2006; Ford 2014), although 
satellite-tracked individuals have been reported off the coast (Bailey 
et al., 2009). Based on modeling of the dynamic topography of the 
region, blue whales could occur in relatively high densities off Oregon 
during summer and fall (Pardo et al. 2015: Hazen et al. 2017). Recent 
phenology analysis of marine mammal sightings revealed a peak of blue 
whale density over the Oregon continental shelf in September, and their 
sighting rates in the region have increased over the past three decades 
as a response to environmental changes influencing prey availability 
shifting their range northward (Derville et al., 2022). 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). Blue whales have been detected 
acoustically off Oregon (McDonald et al., 1995; Stafford et al., 1998; 
Von Saunder and Barlow 1999). Blue whales could be encountered in the 
proposed survey areas.

[[Page 37567]]

Fin Whale

    The fin whale is widely distributed in all the World's oceans 
(Gambell 1985b), although it is most abundant in temperate and cold 
waters (Aguilar and Garc[iacute]a-Vernet 2018). Nonetheless, its 
overall range and distribution are not well known (Jefferson et al., 
2015). A review of fin whale distribution in the North Pacific noted 
the lack of sightings across pelagic waters between eastern and western 
winter areas (Mizroch et al., 2009). Fin whales most commonly occur 
offshore, but can also be found in coastal areas (Jefferson et al., 
2015).
    Most populations migrate seasonally between temperate waters where 
mating and calving occur in winter, and polar waters where feeding 
occurs in summer (Aguilar and Garc[iacute]a-Vernet 2018). Some animals 
may remain at high latitudes in winter or low latitudes in summer 
(Edwards et al., 2015). The northern and southern fin whale populations 
likely do not interact owing to their alternate seasonal migration; the 
resulting genetic isolation has led to the recognition of two 
subspecies, B. physalus quoyi and B. p. physalus in the Southern and 
Northern hemispheres, respectively (Anguilar and Garc[iacute]a-Vernet 
2018). The fin whale is known to use the shelf edge as a migration 
route (Evans 1987). Sergeant (1977) suggested that fin whales tend to 
follow steep slope contours, either because they detect them readily, 
or because the contours are areas of high biological productivity. 
However, fin whale movements have been reported to be complex 
(Jefferson et al., 2015). Stafford et al. (2009) noted that sea-surface 
temperature is a good predictor variable for fin whale call detections 
in the North Pacific.
    North Pacific fin whales summer from the Chukchi Sea to California 
and winter from California southwards (Gambell 1985b). Information 
about the seasonal distribution of fin whales in the North Pacific has 
been obtained from the detection of fin whale calls by bottom-mounted, 
offshore hydrophone arrays along the U.S. Pacific coast, in the central 
North Pacific, and in the western Aleutian Islands (Moore et al., 1998, 
2006; Watkins et al., 2000a,b; Stafford et al., 2007, 2009). Fin whale 
calls are recorded in the North Pacific year-round (e.g., Moore et al., 
2006; Stafford et al., 2007, 2009; Edwards et al., 2015). In the 
central North Pacific, the Gulf of Alaska, and Aleutian Islands, call 
rates peak during fall and winter (Moore et al., 1998, 2006; Watkins et 
al., 2000a,b; Stafford et al., 2009).
    Fin whales are routinely sighted during surveys off Oregon and 
Washington (Barlow and Forney 2007; Barlow 2010, 2016; Adams et al., 
2014; Calambokidis et al., 2015; Edwards et al., 2015; Carretta et al., 
2021), including in coastal as well as offshore waters. They have also 
been detected acoustically in those waters during June-August (Edwards 
et al., 2015). Eight fin whale sightings (19 animals) were made off 
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate 
seismic survey; sightings were made in waters 2369-3940 m deep (RPS 
2012b). Fourteen fin whale sightings (28 animals) were made during the 
July 2012 L-DEO seismic surveys off southern Washington (RPS 2012a). No 
fin whales were sighted during the July 2012 L-DEO seismic survey off 
Oregon (RPS 2012c). During L-DEO's Cascadia survey during June-July 
2021, five sightings of seven fin whales were made off Oregon (RPS 
2021b). Fine whales were also seen off southern Oregon during July 2012 
in water >2000 m deep during surveys by Adams et al., (2014). Fin 
whales are likely to be encountered in the proposed survey area.

Sei Whale

    The sei whale occurs in all ocean basins (Horwood 2018), but 
appears to prefer mid-latitude temperate waters (Jefferson et al. 
2015). It undertakes seasonal migrations to feed in subpolar latitudes 
during summer and returns to lower latitudes during winter to calve 
(Horwood 2018). The sei whale is pelagic and generally not found in 
coastal waters (Harwood and Wilson 2001). It occurs in deeper waters 
characteristic of the continental shelf edge region (Hain et al., 1985) 
and in other regions of steep bathymetric relief such as seamounts and 
canyons (Kenney and Winn 1987; Gregr and Trites 2001). On feeding 
grounds, sei whales associate with oceanic frontal systems (Horwood 
1987) such as the cold eastern currents in the North Pacific (Perry et 
al., 1999). Sei whales 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 
California, as well as in the western Pacific from Japan to Korea. Its 
winter distribution is concentrated at ~20[deg] N (Rice 1998).
    Sei whales are rare in the waters off Washington, Oregon, and 
California (Brueggeman et al., 1990; Green et al., 1992; Barlow 1994, 
1997). Less than 20 confirmed sightings were reported in that region 
during extensive surveys during 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, 2010, 2014; Forney 
2007; Carretta et al., 2021). Based on surveys conducted in 1991-2008, 
the estimated abundance 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). No sei whales were sighted during the 
summer 2012 or 2021 L-DEO seismic surveys off Oregon and Washington 
(RPS 2012a,c, 2021). Sei whales could be encountered during the 
proposed survey, although this species is considered rare in these 
waters.

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 south to within 2[deg] of the Equator (Perrin et al., 
2018).
    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 
nearshore waters off west coast of the U.S. (Dorsey et al., 1990).
    Sightings have been made off Oregon and Washington in shelf and 
deeper waters (Green et al., 1992; Adams et al., 2014; Barlow 2016; 
Carretta et al., 2021). 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 
Oregon/

[[Page 37568]]

Washington during L-DEO's summer seismic surveys in 2012 or 2021 (RPS 
2012b,c, 2021). One minke whale was seen during the July 2012 L-DEO 
seismic survey off southern Washington (RPS 2012a). Minke whales are 
expected to be uncommon in the proposed survey areas.

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 
juveniles animals of both sexes generally occur in tropical and 
subtropical waters, whereas adult makes are commonly found alone or in 
the 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). Females generally 
inhabit waters over 1000 m deep at latitudes under 40 degrees where sea 
surface temperatures are under 15 degrees Celsius; adult males move to 
higher latitudes as they grow older and larger in size, returning to 
warm-water breeding grounds according to an unknown schedule (Whitehead 
2018).
    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). Sperm 
whales were sighted during surveys off Oregon in October 2011 and off 
Washington in June 2011 (Adams et al., 2014). Sperm whale sightings 
were also made off Oregon and Washington during the 2014 Southwest 
Fisheries Science Center (SWFSC) vessel survey (Barlow 2016). Sperm 
whale were detected acoustically in waters off Oregon and Washington in 
August 2016 during the SWFSC Passive Acoustics Survey of Cetacean 
Abundance Levels (PASCAL) study using drifting acoustic recorders 
(Keating et al., 2018). 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 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 
an inshore site from June through January 2009, with an absence of 
calls during February through May (Sirovic et al., 2012). Sperm whales 
are likely to be encountered in the proposed survey areas.

Baird's Beaked Whale

    Baird's beaked whale has a fairly extensive range across the North 
Pacific north of 30[deg] N, and strandings have occurred as far north 
as the Pribilof Islands (Rice 1986). Two forms of Baird's beaked whales 
were previously recognized--the common slate-gray form and a smaller, 
rare black form (Morin et al., 2017), however the small body size of 
physically mature individuals in the latter form, as well as recent 
genetic studies (Morin et al., 2017) have identified this form as a new 
species called Sato's beaked whale (Berardius minimus) (Yamada et al., 
2019).The gray form is seen off Japan, in the Aleutians, and on the 
west coast of North America, whereas the black form has been reported 
for northern Japan and the Aleutians (Morin et al., 2017). Baird's 
beaked whale is currently divided into three distinct stocks: Sea of 
Japan, Okhotsk Sea, and Bering Sea/eastern North Pacific (Balcomb 1989; 
Reyes 1991). Baird's beaked whales sometimes are seen close to shore, 
but their primary habitat is over or near the continental slope and 
oceanic seamounts in waters 1000-3000 m deep (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., 2021) 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.
    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 >2000 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 in the waters off Oregon and Washington in 
August 2016 during the SWFSC PASCAL study using drifting acoustic 
recorders (Keating et al., 2018). Baird's beaked whales could be 
encountered in the proposed survey regions.

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 >1000 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). Records of Cuvier's 
beaked whale in British Columbia are scarce, although 20 strandings, 
one incidental catch, and five sightings have been reported, including 
off western Vancouver Island (Ford 2014). Most strandings have been 
reported in summer (Ford 2014).
    Four beaked whale sightings were reported in water depths over 2000 
m off Oregon/Washington during surveys in 2008 (Barlow 2010). None were 
seen in 1996 or 2001 (Barlow 2003), and several were recorded from 
1991-1995 (Barlow 1997). One Cuvier's beaked whale sighting was made 
during surveys in 2014 (Barlow 2016). Acoustic monitoring in Washington 
offshore waters detected Cuvier's beaked whale calls between January 
and November 2011 (Sirovic et al., 2012b in USN 2015). Cuvier's beaked 
whales were

[[Page 37569]]

detected acoustically in waters off Oregon and Washington in August 
2016 during the SWFSC PASCAL study using drifting acoustic recorders 
(Keating et al., 2018). Curvier's beaked whales could be encountered 
during the proposed surveys.

Blainville's Beaked Whale

    Blainville's beaked whale is found in tropical and warm temperate 
waters of all oceans (Pitman 2018). It has the widest distribution 
throughout the world of all Mesoplodon species (Pitman 2018). 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).
    There was one acoustic encounter with Blainville's beaked whales 
recorded in Quinault Canyon off Washington in waters 1400 m deep during 
2011 (Baumann-Pickering et al., 2014). Blainville's beaked whales were 
not detected acoustically off Washington or Oregon during the August 
2016 SWFSC PASCAL study using drifting acoustic recorders (Keating et 
al., 2018). Although Blainville's beaked whales could be encountered 
during the proposed surveys, an encounter would be unlikely because the 
proposed survey regions are beyond the northern limits of this tropical 
species' usual distribution.

Hubbs' 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 west coast of the U.S. (MacLeod et al., 2006). 
Most are from California, but at least seven strandings have been 
recorded along the B.C. coast as far north as Prince Rupert (Mead 1989; 
Houston 1990a; Willis and Baird 1998; Ford 2014). Several strandings 
are known from Washington/Oregon (e.g., Norman et al., 2004; Griffiths 
et al., 2019). In addition, at least two sightings off Oregon/
Washington, but outside the U.S. EEZ, were reported by Carretta et al. 
(2021), and one bycatch record off Oregon/Washington was reported by 
Griffiths et al. (2019). During the 2016 SWFSC PASCAL study using 
drifting acoustic recorders, detections were made of beaked whale 
sounds presumed to be from Hubbs' beaked whales off Washington and 
Oregon during August (Griffiths et al., 2019). This species seems to be 
less common in the region than some of the other beaked whales.

Stejneger's Beaked Whale

    Stejneger's beaked whale occurs in subarctic and cool temperate 
waters of the North Pacific (Mead 1989). Most records are from Alaskan 
waters, and the Aleutian Islands appear to be its center of 
distribution (Mead 1989; Wade et al., 2003). 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). 
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-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 off Oregon and Washington in August 
2016 during the SWFSC PASCAL study using drifting acoustic recorders 
(Keating et al., 2018).

Striped Dolphin

    The striped dolphin has a cosmopolitan distribution in tropical to 
warm temperate waters from ~50[deg] N to 40[deg] S (Perrin et al., 
1994; Jefferson et al., 2015). It occurs primarily in pelagic waters 
outside of the continental shelf, but has been observed approaching 
shore where there is deep water close to the coast (Jefferson et al., 
2015). Striped dolphins regularly occur off California (Becker et al., 
2012), including as far offshore as ~300 n.mi. during NOAA Fisheries 
vessel surveys (Carretta et al., 2021). However, few sightings have 
been made off Oregon, and no sightings have been reported for 
Washington (Carretta et al., 2021). However, 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; based on those sightings, Barlow (2016) 
calculated an abundance estimate of 13,171 striped dolphins for Oregon/
Washington. The abundance estimates for 2001, 2005, and 2008 were zero 
(Barlow 2016). It is possible, although unlikely, that striped dolphins 
could be encountered in the proposed survey area.

Common Dolphin

    The common dolphin is found in tropical and warm temperate oceans 
around the world (Jefferson et al., 2015), ranging from ~60[deg] N to 
~50[deg] S (Jefferson et al., 2015). It is the most abundant dolphin 
species in offshore areas of warm-temperate regions in the Atlantic and 
Pacific (Perrin 2018). It can be found in oceanic and coastal habitats; 
it 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., 2021). 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 estuary during summer, with 
lower densities off southern Oregon (Becker et al., 2014). A group of 
six common dolphins was sighted during L-DEO's Cascadia summer survey 
just south of the Columbia River off Oregon (RPS 2021b). Common 
dolphins could be encountered in the proposed survey regions.

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, 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)

[[Page 37570]]

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%) 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).
    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 (RPS 2012b). There were fifteen Pacific white-
sided dolphin sightings (462 animals) made during the July 2012 L-DEO 
seismic surveys off southern Washington (RPS 2012a). This species was 
not sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 
2012c). Numerous Pacific white-sided dolphin sightings were made during 
L-DEO's Cascadia summer survey off Oregon and Washington (RPS 2021b). 
Pacific white-sided dolphins are likely to be common in the proposed 
survey regions.

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, the northern right 
whale dolphin is one of the most common marine mammal species, 
occurring primarily in shelf and slope waters ~100 to >2000 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).
    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). During L-DEO's Cascadia survey during June-July 
2021, one sighting of 15 northern right whale dolphins was made off 
Washington, and another sighting of 12 individuals was made off Oregon 
(RPS 2021b). Northern right whale dolphins are likely to be encountered 
in the proposed survey regions.

Risso's Dolphin

    Risso's dolphin is distributed worldwide in mid-temperate and 
tropical oceans (Kruse et al., 1999). 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 occurs from coastal to 
deep water (~200-1000 m depth), it shows a strong preference for mid-
temperate waters of upper continental slopes and steep shelf-edge areas 
(Hartman 2018).
    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 (Barlow 2016; Carretta et al., 2021). 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). Risso's dolphins could be encountered in the 
proposed survey regions.

Killer Whale

    The killer whale is cosmopolitan and globally fairly abundant, 
being observed in all oceans of the world (Ford 2018). It is very 
common in temperate waters and also frequents tropical waters, at least 
seasonally (Heyning and Dahlheim 1988). There are three distinct 
ecotypes, or forms, of killer whales recognized in the north Pacific: 
Resident, transient, and offshore. The three ecotypes differ 
morphologically, ecologically, behaviorally, and genetically. Resident 
killer whales exclusively prey upon fish, with a clear preference for 
salmon (Ford and Ellis 2006; Hanson et al., 2010; Ford et al., 2016), 
while transient killer whales exclusively prey upon marine mammals 
(Carretta et al., 2019). Less is known about offshore killer whales, 
but they are believed to consume primarily fish, including several 
species of shark (Dahlheim et

[[Page 37571]]

al., 2008). Killer whales occur in inshore inlets, along the coast, 
over the continental shelf, and in offshore waters (Ford 2014).
    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 British 
Columbia through parts of the Southeast Alaska; (3) Southern Residents, 
mainly in inland waters of Washington State and southern British 
Columbia; (4) Gulf of Alaska, Aleutians, and Bering Sea Transients, 
from Prince William Sound through the Aleutians and Bering Sea; (5) AT1 
Transients, from Prince William Sound through the Kenai Fjords; (6) 
West Coast Transients, from California through Southeast Alaska; (7) 
Offshore, from California through Alaska; and (8) Hawaiian (Muto et 
al., 2021; Carretta et al., 2021). Individuals from the West Coast 
Transient and Offshore stocks could be encountered in the proposed 
project areas. It is unlikely that individuals from the endangered 
Eastern North Pacific Southern Resident stock would be encountered in 
the offshore survey regions, as they are primarily found along the 
coasts and the proposed survey is located in waters deeper than 1600 m 
and at least 46 km from the shoreline.
    The main diet of transient killer whales consists of marine 
mammals, in particular porpoises and seals. West coast transient killer 
whales (also known as Bigg's killer whales) range from Southeast Alaska 
to California (Muto et al., 2021). The seasonal movements of transients 
are largely unpredictable (Baird 1994; Ford 2014). 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. Two of 17 killer whales that 
stranded in Oregon were confirmed as transient (Stevens et al., 1989 in 
Norman et al., 2004).
    Little is known about offshore killer whales, but they occur 
primarily over shelf waters and feed on fish, especially sharks (Ford 
2014). Dahlheim et al., (2008) reported sightings in Southeast Alaska 
during spring and summer. Eleven sightings of approximately 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. Killer whales were sighted 
off Washington in July and September 2012 (Adams et al., 2014).
    During L-DEO's Cascadia surveys during June through July 2021 in 
the Northeast Pacific Ocean, a sighting of 20 killer whales was made 
near the shelf edge off northern Oregon (RPS 2021b). Killer whales 
could be encountered during the proposed survey, although it is 
unlikely the endangered Southern Resident Killer whales would occur as 
far offshore as the survey regions.

Pygmy and Dwarf Sperm Whale

    Dwarf and pygmy sperm whales are distributed throughout tropical 
and temperate waters of the Atlantic, Pacific, and Indian oceans, but 
their precise distributions are unknown because much of what we know of 
the species comes from strandings (McAlpine 2018). They are difficult 
to sight at sea, because of their dive behavior and 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 often 
difficult to distinguish from one another when sighted (McAlpine 2018).
    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; Jefferson et al., 2015). Stomach content 
analyses from stranded whales further support this distribution 
(McAlpine 2018). Recent data indicate that both Kogia species feed in 
the water column and on/near the seabed, likely using echolocation to 
search for prey (McAlpine 2018). Several studies have suggested that 
pygmy sperm whales live and feed mostly beyond the continental shelf 
edge, whereas dwarf sperm whales tend to occur closer to shore, often 
over the continental shelf and slope (Rice 1998; Wang et al., 2002; 
MacLeod et al., 2004; McAlpine 2018). 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; McAlpine 2018).
    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., 2021). 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. Despite the limited number of 
sightings, it is possible that pygmy or dwarf sperm whales could be 
encountered within the proposed project areas.

Dall's Porpoise

    Dall's porpoise is found in temperate to subarctic 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 (>2500 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; Fleming et al., 2018; Carretta 
et al., 2021). 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). 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-

[[Page 37572]]

July 2012 L-DEO Juan de Fuca plate seismic survey (RPS 2012b). There 
were 16 Dall's porpoise sightings (54 animals) made during the July 
2012 L-DEO seismic surveys off southern Washington (RPS 2012a). This 
species was not sighted during the July 2012 L-DEO seismic survey off 
Oregon (RPS 2012c). During L-DEO's Cascadia survey during June-July 
2021, one sighting of four individuals was made near the shelf edge off 
the Columbia River (RPS 2021b). Dall's porpoise is likely to be 
encountered during the proposed seismic surveys.

Northern Fur Seal

    The northern fur seal is endemic to the North Pacific Ocean and 
occurs from southern California to the Bering Sea, Okhotsk Sea, and 
Honshu Island, Japan (Muto et al., 2021). During the breeding season, 
most of the worldwide population of northern fur seals inhabits the 
Pribilof Islands in the southern Bering Sea (NMFS 2007; Lee et al., 
2014; Muto et al., 2021). The rest of the population occurs at 
rookeries on Bogoslof Island in the Bering Sea, in Russia (Commander 
Islands, Robben Island, Kuril Islands), on San Miguel Island in 
southern California (NMFS 1993; Lee et al., 2014), and on the Farallon 
Islands off central California (Muto et al., 2021). In the U.S., two 
stocks are recognized--the Eastern Pacific and the California stocks 
(Muto et al., 2021). The Eastern Pacific stock ranges from the Pribilof 
Islands and Bogoslof Island in the Bering Sea during summer to 
California during winter (Muto et al., 2021). When not on rookery 
islands, northern fur seals are primarily pelagic but occasionally haul 
out on rocky shorelines (Muto et al., 2021).
    During the breeding season, adult males usually come ashore in May-
August and may sometimes be present until November; adult females are 
found ashore from June-November (Carretta et al., 2021; Muto et al., 
2021). After reproduction, northern fur seals spend the next 7-8 months 
feeding at sea (Roppel 1984). Immature seals can remain in southern 
foraging areas year-round until they are old enough to mate (NMFS 
2007). In November, females and pups leave the Pribilof Islands and 
migrate through the Gulf of Alaska to feeding areas primarily off the 
coasts of B.C., Washington, Oregon, and California before migrating 
north again to the rookeries in spring (Ream et al., 2005; Pelland et 
al., 2014). Males usually migrate only as far south as the Gulf of 
Alaska (Kajimura 1984). Ream et al. (2005) showed that migrating 
females moved over the continental shelf as they migrated 
southeasterly. Instead of following depth contours, their travel 
corresponded with movements of the Alaska Gyre and the North Pacific 
Current (Ream et al., 2005). Their foraging areas were associated with 
eddies, the subarctic-subtropical transition region, and coastal mixing 
(Ream et al., 2005; Alford et al., 2005). Some juveniles and non-
pregnant females may remain in the Gulf of Alaska throughout the summer 
(Calkins 1986). The northern fur seals spends ~90% 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. Pups from the California stock also 
migrate to Washington, Oregon, and northern California after weaning 
(Lea et al., 2009).
    Northern fur seals were seen throughout the North Pacific during 
surveys conducted during 1987-1990, including off Washington and Oregon 
(Buckland et al., 1993). Tagged adult fur seals were tracked from the 
Pribilof Islands to the waters off Washington/Oregon/California, with 
recorded movement throughout the region (Pelland et al., 2014). Tracked 
adult male fur seals that were tagged on St. Paul Island in the Bering 
Sea in October 2009 wintered in the Bering Sea or northern North 
Pacific Ocean; females migrated to the Gulf of Alaska and the 
California Current (Sterling et al., 2014). Some individuals reach 
California by December, after which time numbers increase off the west 
coast of North America (Ford 2014). The peak density shifts over the 
course of the winter and spring, with peak densities occurring in 
California in February, April off Oregon and Washington, and May off 
B.C. and Southeast Alaska (Ford 2014). The use of continental shelf and 
slope waters of B.C. and the northwestern U.S. by adult females during 
winter is well documented from pelagic sealing data (Bigg 1990).
    Bonnell et al., (1992) noted the presence of northern fur seals 
year-round off Oregon/Washington, with the greatest numbers (87%) 
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 
(>2000 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). During L-DEO's 
Cascadia survey during June-July 2021, one northern fur seal was 
sighted off Washington near the shelf edge (RPS 2021b).
    Northern fur seals could be observed in the proposed survey 
regions, in particular females and juveniles. However, adult males are 
generally ashore during the reproductive season from May-August; adult 
females are generally ashore from June through November.

Guadalupe Fur Seal

    Most breeding and births occur at Isla Guadalupe, Mexico; a 
secondary rookery exists at Isla Benito del Este (Maravilla-Chavez and 
Lowry 1999; Aurioles-Gamboa et al., 2010). A few Guadalupe fur seals 
are known to occur at California sea lion rookeries in the Channel 
Islands, primarily San Nicolas and San Miguel islands, and sightings 
have also been made at Santa Barbara and San Clemente islands (Stewart 
et al., 1987; Carretta et al., 2021). Guadalupe fur seals prefer rocky 
habitat for breeding and hauling out. They generally haul out at the 
base of towering cliffs on shores characterized by solid rock and large 
lava blocks (Peterson et al., 1968), although they can also inhabit 
caves and recesses (Belcher and Lee 2002). While at sea, this species 
usually is solitary but typically gathers in the hundreds to thousands 
at breeding sites.
    During the summer breeding season, most adults occur at rookeries 
in Mexico (Norris 2017 in USN 2019; Carretta et al., 2021). Following 
the breeding season, adult males tend to move northward to forage. 
Females have been observed feeding south of Guadalupe Island, making an 
average round trip of 2375 km (Ronald and Gots 2003). Several 
rehabilitated Guadalupe fur seals that were satellite tagged and 
released in central California traveled as far north as B.C. (Norris et 
al., 2015; Norris 2017 in USN 2019). Fur seals younger than two years 
old are more likely to travel to more northerly, offshore areas than 
older fur seals (Norris 2017 in USN 2019). Stranding data also 
indicates that fur seals younger than 2 years are more likely to occur 
in the proposed survey area, as this age class was most frequently 
reported (Lambourn et al., 2012 in USN 2019). During 2015-2021, 724 
Guadalupe fur seals stranded on the West Coast of the U.S., including 
182 strandings along the coasts of Oregon and Washington during 2019-
2021; NMFS declared this an unusual mortality event (NOAA 2021d). 
Guadalupe fur seals could be

[[Page 37573]]

encountered during the proposed seismic surveys, but most animals are 
likely to occur at their breeding sites farther south at the time of 
the surveys.

California Sea Lion

    The primary range of the California sea lion includes the coastal 
areas and offshore islands of the eastern North Pacific Ocean from B.C. 
to central Mexico, including the Gulf of California (Jefferson et al., 
2015). However, its distribution is expanding (Jefferson et al., 2015), 
and its secondary range extends into the Gulf of Alaska (Maniscalco et 
al., 2004) and southern Mexico (Gallo-Reynoso and Sol[oacute]rzano-
Velasco 1991), where it is occasionally recorded.
    California sea lion rookeries are on islands located in southern 
California, western Baja California, and the Gulf of California 
(Carretta et al., 2021). Five genetically distinct geographic 
populations have been identified: (1) Pacific Temperate (includes 
rookeries in U.S. waters and the Coronados Islands to the south), (2) 
Pacific Subtropical, (3) Southern Gulf of California, (4) Central Gulf 
of California, and (5) Northern Gulf of California (Schramm et al., 
2009). Animals from the Pacific Temperate population occur in the 
proposed project area.
    In California and Baja California, births occur on land from mid-
May to late-June. During August and September, after the mating season, 
the adult males migrate northward to feeding areas as far north as 
Washington (Puget Sound) and B.C. (Lowry et al., 1992). They remain 
there until spring (March-May), when they migrate back to the breeding 
colonies (Lowry et al., 1992; Weise et al., 2006). The distribution of 
immature California sea lions is less well known but some make 
northward migrations that are shorter in length than the migrations of 
adult males (Huber 1991). However, most immature seals are presumed to 
remain near the rookeries for most of the year, as are females and pups 
(Lowry et al., 1992).
    California sea lions are coastal animals that often haul out on 
shore throughout the year, but peak numbers off Oregon and Washington 
occur during the fall (Bonnell et al., 1992). During aerial surveys off 
the coasts of Oregon and Washington during 1989-1990, California sea 
lions were sighted at sea during the fall and winter, but no sightings 
were made during June-August (Bonnell et al., 1992). Numbers off Oregon 
decrease during winter, as animals travel further north (Mate 1975 in 
Bonnell et al., 1992). King (1983) noted that sea lions are rarely 
found more than 16 km offshore. During fall and winter surveys off 
Oregon and Washington, mean distance from shore was ~13 km and most 
were observed in water <200 m deep; however, sightings were made in 
water as deep as 356 m (Bonnell et al., 1992). Weise et al., (2006) 
reported that males normally forage almost exclusively over the 
continental shelf, but during anomalous climatic conditions they can 
forage farther out to sea (up to 450 km offshore).
    During aerial surveys over the shelf and slope off Oregon and 
Washington (Adams et al., 2014), California sea lions were seen during 
all survey months (January-February, June-July, September-October). 
Although most sightings occurred on the shelf, during February 2012, 
one sighting was made near the 2000-m depth contour, and during June 
2011 and July 2012, sightings were made along the 200-m isobath off 
southern Oregon (Adams et al., 2014). During October 2011, sightings 
were made off the Columbia River estuary near the 200-m isopleth and on 
the southern Oregon shelf; during September 2012, sightings occurred in 
nearshore waters off Washington and in shelf waters along the coast of 
Oregon (Adams et al., 2014). Adams et al., (2014) reported sightings 
more than 60 km off the coast of Oregon. During L-DEO's Cascadia survey 
during June-July 2021, four sightings of nine California sea lions were 
made in nearshore waters off Oregon (RPS 2021b). California sea lions 
were also taken as bycatch off Washington and Oregon in the west coast 
groundfish fishery during 2002-2009 (Jannot et al., 2011). California 
sea lions could be encountered in the proposed project regions.

Steller Sea Lion

    The Steller sea lion occurs along the North Pacific Rim from 
northern Japan to California (Loughlin et al., 1984). It is distributed 
around the coasts to the outer shelf from northern Japan through the 
Kuril Islands and Okhotsk Sea, through the Aleutian Islands, central 
Bering Sea, southern Alaska, and south to California (NOAA 2021e). 
There are two stocks, or DPSs, of Steller sea lions--the Western and 
Eastern DPSs, which are divided at 144[deg] W longitude (Muto et al., 
2021). The Western DPS is listed as endangered and includes animals 
that occur in Japan and Russia (Muto et al., 2021); the Eastern DPS was 
delisted from threatened in 2013 (NMFS 2013a). Only individuals from 
the Eastern DPS could occur in the proposed survey regions.
    Steller sea lions typically inhabit waters from the coast to the 
outer continental shelf and slope throughout their range; they are not 
considered migratory, although foraging animals can travel long 
distances (Loughlin et al., 2003; Raum-Suryan et al., 2002). Rookeries 
of Steller sea lions from the Eastern DPS are located in southeast 
Alaska, B.C., Oregon, and California; there are no rookeries in 
Washington (NMFS 2013a; Muto et al., 2021). Breeding adults occupy 
rookeries from late-May to early-July (NMFS 2008). Federally designated 
critical habitat for Steller sea lions in Oregon and California 
includes all rookeries (NMFS 1993). Although the Eastern DPS was 
delisted from the ESA in 2013, the designated critical habitat remains 
valid (NOAA 2021e). The critical habitat in Oregon is located along the 
coast at Rogue Reef (Pyramid Rock) and Orford Reef (Long Brown Rock and 
Seal Rock). The critical habitat area includes aquatic zones that 
extend 0.9 km seaward and air zones extending 0.9 km above these 
terrestrial and aquatic zones (NMFS 1993). The nearest proposed seismic 
transect would be located 46 km from shore.
    Non-breeding adults use haulouts or occupy sites at the periphery 
of rookeries during the breeding season (NMFS 2008). Pupping occurs 
from mid-May to mid-July (Pitcher and Calkins 1981) and peaks in June 
(Pitcher et al., 2002). Territorial males fast and remain on land 
during the breeding season (NMFS 2008). Females with pups generally 
stay within 30 km of the rookeries in shallow (30-120 m) water when 
feeding (NMFS 2008). Tagged juvenile sea lions showed localized 
movements near shore (Briggs et al., 2005). Loughlin et al., (2003) 
reported that most (88%) at-sea movements of juvenile Steller sea lions 
in the Aleutian Islands were short (<15 km) foraging trips. The mean 
distance of juvenile sea lion trips at sea was 16.6 km, and the maximum 
trip distance recorded was 447 km. Long-range trips represented 6% of 
all trips at sea, and trip distance and duration increase with age 
(Loughlin et al., 2003; Call et al., 2007). Although Steller sea lions 
are not considered migratory, foraging animals can travel long 
distances outside of the breeding season (Loughlin et al., 2003; Raum-
Suryan et al., 2002). During the summer, they mostly forage within 60 
km from the coast; during winter, they can range up to 200 km from 
shore (Ford 2014).
    During surveys off the coasts of Oregon and Washington, Bonnell et 
al., (1992) noted that 89% of sea lions occurred over the shelf at a 
mean

[[Page 37574]]

distance of 21 km from the coast and near or in waters <200 m deep; the 
farthest sighting occurred ~40 km from shore, and the deepest sighting 
location was 1611 m deep. Sightings were made along the 200-m depth 
contour throughout the year (Bonnell et al., 1992). During aerial 
surveys over the shelf and slope off Oregon and Washington, one Steller 
sea lion was seen on the Oregon shelf during January 2011, and two 
sightings totaling eight individuals were made on September 2012 off 
southern Oregon (Adams et al., 2014). During a survey off Washington/
Oregon June-July 2012, two Steller sea lions were seen from R/V 
Langseth (RPS 2012b) off southern Oregon. Eight sightings of 11 
individuals were made from R//V Northern Light during a survey off 
southern Washington during July 2012 (RPS 2012a). No sightings were 
made during L-DEO's Cascadia summer survey off Oregon and Washington 
(RPS 2021b). Steller sea lions were also taken as bycatch off southern 
Oregon in the west coast groundfish fishery during 2002-2009 (Jannot et 
al., 2011). Steller sea lions could be encountered in the proposed 
project regions.

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). 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-March (Stewart 
and Huber 1993). Females arrive in late December or January and give 
birth within ~1 week of their arrival. Juvenile elephant seals 
typically leave the rookeries in April or May and head north, traveling 
an average of 900-1000 km. 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. Adult females and juveniles forage in the California 
current off California to B.C. (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 >2000 m deep. Telemetry data indicate that they range much 
farther offshore than that (Stewart and DeLong 1995). 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. Most elephant seal 
sightings at sea off Washington were made during June, July, and 
September; off Oregon, sightings were recorded from November through 
May (Bonnell et al., 1992). Northern elephant seal pups have been 
sighted at haulouts in the inland waters of Washington State (Jeffries 
et al., 2000), and at least three were reported to have been born there 
(Hayward 2003). 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). Northern elephant seals 
could be encountered during the proposed seismic surveys.

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. 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, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 2.

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

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).

[[Page 37575]]

    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a discussion of the ways that L-DEO's 
specified activity may impact marine mammals and their habitat. The 
Estimated Take 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 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 may or 
may not 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 a marine mammals found later in this document.
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz (Hz) or cycles per second. Wavelength is the 
distance between two peaks or corresponding points of a sound wave 
(length of one cycle). Higher frequency sounds have shorter wavelengths 
than lower frequency sounds, and typically attenuate (decrease) more 
rapidly, except in certain cases in shallower water. Amplitude is the 
height of the sound pressure wave or the ``loudness'' of a sound and is 
typically described using the relative unit of the dB. A sound pressure 
level (SPL) in dB is described as the ratio between a measured pressure 
and a reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)) and is a logarithmic unit that accounts for large variations 
in amplitude; therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. The source level (SL) represents the 
SPL referenced at a distance of 1 m from the source (referenced to 1 
[mu]Pa) while the received level is the SPL at the listener's position 
(referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they may be accounted for in the summation of 
pressure levels (Hastings and Popper, 2005). This measurement is often 
used in the context of discussing behavioral effects, in part because 
behavioral effects, which often result from auditory cues, may be 
better expressed through averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa\2\-s) 
represents the total energy contained within a pulse and considers both 
intensity and duration of exposure. Peak sound pressure (also referred 
to as zero-to-peak sound pressure or 0-p) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source and is represented in the same units as the rms sound pressure. 
Another common metric is peak-to-peak sound pressure (pk-pk), which is 
the algebraic difference between the peak positive and peak negative 
sound pressures. Peak-to-peak pressure is typically approximately 6 dB 
higher than peak pressure (Southall et al., 2007).
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or may radiate in all directions 
(omnidirectional sources), as is the case for pulses produced by the 
airgun arrays considered here. The compressions and decompressions 
associated with sound waves are detected as changes in pressure by 
aquatic life and man-made sound receptors such as hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound. Ambient 
sound is defined as environmental background sound levels lacking a 
single source or point (Richardson et al., 1995), and the sound level 
of a region is defined by the total acoustical energy being generated 
by known and unknown sources. These sources may include physical (e.g., 
wind and waves, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic (e.g., vessels, dredging, construction) sound. A number 
of sources contribute to ambient sound, including the following 
(Richardson et al., 1995):
     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient sound for frequencies between 200 Hz and 50 
kHz (Mitson, 1995). In general, ambient sound levels tend to increase 
with increasing wind speed and wave height. Surf sound becomes 
important near shore, with measurements collected at a distance of 8.5 
km from shore showing an increase of 10 dB in the 100 to 700 Hz band 
during heavy surf conditions;
     Precipitation: Sound from rain and hail impacting the 
water surface can become an important component of total sound at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times;
     Biological: Marine mammals can contribute significantly to 
ambient sound levels, as can some fish and snapping shrimp. The 
frequency band for biological contributions is from approximately 12 Hz 
to over 100 kHz; and
     Anthropogenic: Sources of ambient sound related to human 
activity include transportation (surface vessels), dredging and 
construction, oil and gas drilling and production, seismic surveys, 
sonar, explosions, and ocean acoustic studies. Vessel noise typically 
dominates the total ambient sound for frequencies between 20 and 300 
Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz 
and, if higher frequency sound levels are created, they attenuate 
rapidly. Sound from identifiable anthropogenic sources other than the 
activity of interest (e.g., a passing vessel) is sometimes termed 
background sound, as opposed to ambient sound.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
human activity) but also on the ability of sound to propagate through 
the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of this dependence on a 
large number of varying factors, ambient

[[Page 37576]]

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 Sound 
Sources'') regarding sound, characteristics of sound types, and metrics 
used in this document. Note that, in the following discussion, we refer 
in many cases to Finneran (2015), a review article concerning studies 
of noise-induced hearing loss conducted from 1996-2015. For study-
specific citations, please see Finneran (2015). 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, if it 
occurs at all, will occur almost exclusively in cases where a noise is 
within an animal's hearing frequency 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 response. 
Third is a zone within which, for signals of high intensity, the 
received level is sufficient to potentially cause discomfort or tissue 
damage to auditory or other systems. Overlaying these zones to a 
certain extent is the area within which masking (i.e., when a sound 
interferes with or masks the ability of an animal to detect a signal of 
interest that is above the absolute hearing threshold) may occur; the 
masking zone may be highly variable in size.
    We describe the more severe effects of certain non-auditory 
physical or physiological effects only briefly as we do not expect that 
use of airgun arrays are reasonably likely to result in such effects 
(see below for further discussion). Potential effects from impulsive 
sound sources can range in severity from effects such as behavioral 
disturbance or tactile perception to physical discomfort, slight injury 
of the internal organs and the auditory system, or mortality (Yelverton 
et al., 1973). Non-auditory physiological effects or injuries that 
theoretically might occur in marine mammals exposed to high level 
underwater sound or as a secondary effect of extreme behavioral 
reactions (e.g., change in dive profile as a result of an avoidance 
reaction) caused by exposure to sound include neurological effects, 
bubble formation, resonance effects, and other types of organ or tissue 
damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack, 
2007; Tal et al., 2015). The survey activities considered here do not 
involve the use of devices such as explosives or mid-frequency tactical 
sonar that are associated with these types of effects.
    Threshold Shift--Marine mammals exposed to high-intensity sound, or 
to lower-intensity sound for prolonged periods, can experience hearing 
threshold shift (TS), which is the loss of hearing sensitivity at 
certain frequency ranges (Finneran, 2015). TS can be permanent (PTS), 
in which case the loss of hearing sensitivity is not fully recoverable, 
or temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Repeated sound exposure that 
leads to TTS could cause PTS. In severe cases of PTS, there can be 
total or partial deafness, while in most cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). In

[[Page 37577]]

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 
typically 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 was 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 direct 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, 2019), Finneran and 
Jenkins (2012), Finneran (2015), and NMFS (2018).
    Behavioral Effects--Behavioral disturbance may include a variety of 
effects, including subtle changes in behavior (e.g., minor or brief 
avoidance of an area or changes in vocalizations), more conspicuous 
changes in similar behavioral activities, and more sustained and/or 
potentially severe reactions, such as displacement from or abandonment 
of high-quality habitat. Behavioral responses to sound are highly 
variable and context-specific, and any reactions depend on numerous 
intrinsic and extrinsic factors (e.g., species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day), as well as the interplay between factors (e.g., 
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007, 
2019; 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

[[Page 37578]]

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 disruptions 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, humpback whales and killer whales have 
been observed to increase the length of their songs or amplitude of 
calls (Miller et al., 2000; Fristrup et al., 2003; Foote et al., 2004; 
Holt et al., 2012), 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,

[[Page 37579]]

providing evidence that fin whales may avoid an area for an extended 
period in the presence of increased noise. The authors hypothesize that 
fin whale acoustic communication is modified to compensate for 
increased background noise and that a sensitization process may play a 
role in the observed temporary displacement.
    Seismic pulses at average received levels of 131 dB re 1 [mu]Pa\2\-
s caused blue whales to increase call production (Di Iorio and Clark, 
2010). In contrast, McDonald et al., (1995) tracked a blue whale with 
seafloor seismometers and reported that it stopped vocalizing and 
changed its travel direction at a range of 10 km from the acoustic 
source vessel (estimated received level 143 dB pk-pk). Blackwell et 
al., (2013) found that bowhead whale call rates dropped significantly 
at onset of airgun use at sites with a median distance of 41-45 km from 
the survey. Blackwell et al. (2015) expanded this analysis to show that 
whales actually increased calling rates as soon as airgun signals were 
detectable before ultimately decreasing calling rates at higher 
received levels (i.e., 10-minute SELcum of ~127 dB). Overall, these 
results suggest that bowhead whales may adjust their vocal output in an 
effort to compensate for noise before ceasing vocalization effort and 
ultimately deflecting from the acoustic source (Blackwell et al., 2013, 
2015). These studies demonstrate that even low levels of noise received 
far from the source can induce changes in vocalization and/or behavior 
for mysticetes.
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Humpback whales showed avoidance behavior in the presence of an 
active seismic array during observational studies and controlled 
exposure experiments in western Australia (McCauley et al., 2000). 
Avoidance may be short-term, with animals returning to the area once 
the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; Stone et 
al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). Longer-term 
displacement is possible, however, which may lead to changes in 
abundance or distribution patterns of the affected species in the 
affected region if habituation to the presence of the sound does not 
occur (e.g., Bejder et al., 2006; Teilmann et al., 2006).
    Forney et al., (2017) detail the potential effects of noise on 
marine mammal populations with high site fidelity, including 
displacement and auditory masking, noting that a lack of observed 
response does not imply absence of fitness costs and that apparent 
tolerance of disturbance may have population-level impacts that are 
less obvious and difficult to document. As we discuss in describing our 
proposed mitigation later in this document, avoidance of overlap 
between disturbing noise and areas and/or times of particular 
importance for sensitive species may be critical to avoiding 
population-level impacts because (particularly for animals with high 
site fidelity) there may be a strong motivation to remain in the area 
despite negative impacts. Forney et al., (2017) state that, for these 
animals, remaining in a disturbed area may reflect a lack of 
alternatives rather than a lack of effects. The authors discuss several 
case studies, including western Pacific gray whales, which are a small 
population of mysticetes believed to be adversely affected by oil and 
gas development off Sakhalin Island, Russia (Weller et al., 2002; 
Reeves et al., 2005). Western gray whales display a high degree of 
interannual site fidelity to the area for foraging purposes, and 
observations in the area during airgun surveys has shown the potential 
for harm caused by displacement from such an important area (Weller et 
al., 2006; Johnson et al., 2007). Forney et al., (2017) also discuss 
beaked whales, noting that anthropogenic effects in areas where they 
are resident could cause severe biological consequences, in part 
because displacement may adversely affect foraging rates, reproduction, 
or health, while an overriding instinct to remain could lead to more 
severe acute effects.
    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 arrays of large airguns 
(considered to be 500 in\3\ or more) were firing, lateral displacement, 
more localized avoidance, or other changes in behavior were evident for 
most odontocetes. However, significant responses to large arrays were 
found only for the minke whale and fin whale. Behavioral

[[Page 37580]]

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, significant masking could disrupt 
behavioral patterns, which in turn could affect fitness for survival 
and reproduction. 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 predicting 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 may be less in situations where the signal and 
noise come from different directions (Richardson et al., 1995), through 
amplitude modulation of the signal, or through other compensatory 
behaviors (Houser and Moore, 2014). Masking can be tested directly in 
captive species (e.g., Erbe, 2008), but in wild populations it must be 
either modeled or inferred from evidence of masking compensation. There 
are few studies addressing real-world masking sounds likely to be 
experienced by marine mammals in the wild (e.g., Branstetter et al., 
2013).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency 
ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand, 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.
    Masking effects of pulsed sounds (even from large arrays of 
airguns) on marine mammal calls and other natural sounds are expected 
to be limited, although there are few specific data on this. Because of 
the intermittent nature and low duty cycle of seismic pulses,

[[Page 37581]]

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., 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, 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.

[[Page 37582]]

    Sounds emitted by the Langseth are low frequency and continuous, 
but would be widely dispersed in both space and time. Vessel traffic 
associated with the proposed survey is of low density compared to 
traffic associated with commercial shipping, industry support vessels, 
or commercial fishing vessels, and would therefore be expected to 
represent an insignificant incremental increase in the total amount of 
anthropogenic sound input to the marine environment, and the effects of 
vessel noise described above are not expected to occur as a result of 
this survey. 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 will travel at a speed of 4.6 kn (8.5 km/h) while 
towing seismic survey gear. 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 propose a robust ship strike avoidance protocol (see Proposed 
Mitigation), which we believe eliminates any foreseeable risk of ship 
strike during transit. 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 proposed 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, the possibility of ship 
strike is discountable and, further, 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 37583]]

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).
    There is no conclusive evidence that exposure to airgun noise 
results in behaviorally-mediated forms of injury. Behaviorally-mediated 
injury (i.e., mass stranding events) has been primarily associated with 
beaked whales exposed to mid-frequency active (MFA) naval sonar. 
Tactical sonar and the alerting stimulus used in Nowacek et al., (2004) 
are very different from the noise produced by airguns. One should 
therefore not expect the same reaction to airgun noise as to these 
other sources. As explained below, military MFA sonar is very different 
from airguns, and one should not assume that airguns will cause the 
same effects as MFA sonar (including strandings).
    To understand why Navy MFA sonar affects beaked whales differently 
than airguns do, it is important to note the distinction between 
behavioral sensitivity and susceptibility to auditory injury. To 
understand the potential for auditory injury in a particular marine 
mammal species in relation to a given acoustic signal, the frequency 
range the species is able to hear is critical, as well as the species' 
auditory sensitivity to frequencies within that range. Current data 
indicate that not all marine mammal species have equal hearing 
capabilities across all frequencies and, therefore, species are grouped 
into hearing groups with generalized hearing ranges assigned on the 
basis of available data (Southall et al., 2007, 2019). Hearing ranges 
as well as auditory sensitivity/susceptibility to frequencies within 
those ranges vary across the different groups. For example, in terms of 
hearing range, the high-frequency cetaceans (e.g., Kogia spp.) have a 
generalized hearing range of frequencies between 275 Hz and 160 kHz, 
while mid-frequency cetaceans--such as dolphins and beaked whales--have 
a generalized hearing range between 150 Hz to 160 kHz. Regarding 
auditory susceptibility within the hearing range, while mid-frequency 
cetaceans and high-frequency cetaceans have roughly similar hearing 
ranges, the high-frequency group is much more susceptible to noise-
induced hearing loss during sound exposure, i.e., these species have 
lower thresholds for these effects than other hearing groups (NMFS, 
2018). Referring to a species as behaviorally sensitive to noise simply 
means that an animal of that species is more likely to respond to lower 
received levels of sound than an animal of another species that is 
considered less behaviorally sensitive. So, while dolphin species and 
beaked whale species--both in the mid-frequency cetacean hearing 
group--are assumed to generally hear the same sounds equally well and 
be equally susceptible to noise-induced hearing loss (auditory injury), 
the best available information indicates that a beaked whale is more 
likely to behaviorally respond to that sound at a lower received level 
compared to an animal from other mid-frequency cetacean species that 
are less behaviorally sensitive. This distinction is important because, 
while beaked whales are more likely to respond behaviorally to sounds 
than are many other species (even at lower levels), they cannot hear 
the predominant, lower frequency sounds from seismic airguns as well as 
sounds that have more energy at frequencies that beaked whales can hear 
better (such as military MFA sonar).
    Navy MFA sonar affects beaked whales differently than airguns do 
because it produces energy at different frequencies than airguns. Mid-
frequency cetacean hearing is generically thought to be best between 
8.8 to 110 kHz, i.e., these cutoff values define the range above and 
below which a species in the group is assumed to have declining 
auditory sensitivity, until reaching frequencies that cannot be heard 
(NMFS, 2018). However, beaked whale hearing is likely best within a 
higher, narrower range (20-80 kHz, with best sensitivity around 40 
kHz), based on a few measurements of hearing in stranded beaked whales 
(Cook et al., 2006; Finneran et al., 2009; Pacini et al., 2011) and 
several studies of acoustic signals produced by beaked whales (e.g., 
Frantzis et al., 2002; Johnson et al., 2004, 2006; Zimmer et al., 
2005). While precaution requires that the full range of audibility be 
considered when assessing risks associated with noise exposure 
(Southall et al., 2007, 2019a2019), animals typically produce sound at 
frequencies where they hear best. More recently, Southall et al., 
(2019) suggested that certain species in the historical mid-frequency 
hearing group (beaked whales, sperm whales, and killer whales) are 
likely more sensitive to lower frequencies within the group's 
generalized hearing range than are other species within the group, and 
state that the data for beaked whales suggest sensitivity to 
approximately 5 kHz. However, this information is consistent with the 
general conclusion that beaked whales (and other mid-frequency 
cetaceans) are relatively insensitive to the frequencies where most 
energy of an airgun signal is found. Military MFA sonar is typically 
considered to operate in the frequency range of approximately 3-14 kHz 
(D'Amico et al., 2009), i.e., outside the range of likely best hearing 
for beaked whales but within or close to the lower bounds, whereas most 
energy in an airgun signal is radiated at much lower frequencies, below 
500 Hz (Dragoset, 1990).
    It is important to distinguish between energy (loudness, measured 
in dB) and frequency (pitch, measured in Hz). In considering the 
potential impacts of mid-frequency components of airgun noise (1-10 
kHz, where beaked whales can be expected to hear) on marine mammal 
hearing, one needs to account for the energy associated with these 
higher frequencies and determine what energy is truly ``significant.'' 
Although there is mid-frequency energy associated with airgun noise (as 
expected from a broadband source), airgun sound is predominantly below 
1 kHz (Breitzke et al., 2008; Tashmukhambetov et al., 2008; Tolstoy et 
al., 2009). As stated by Richardson et al. (1995), ``[. . .] most 
emitted [seismic airgun] energy is at 10-120 Hz, but the pulses contain 
some energy up to 500-1,000 Hz.'' Tolstoy et al., (2009) conducted 
empirical measurements, demonstrating that sound energy levels 
associated with airguns were at least 20 decibels (dB) lower at 1 kHz 
(considered ``mid-frequency'') compared to higher energy levels 
associated with lower frequencies (below 300 Hz) (``all but a small 
fraction of the total energy being concentrated in the 10-300 Hz 
range'' [Tolstoy et al., 2009]), and at higher frequencies (e.g., 2.6-4 
kHz), power might be less than 10 percent of the peak power at 10 Hz 
(Yoder, 2002). Energy levels measured by Tolstoy et al., (2009) were 
even lower at frequencies above 1 kHz. In addition, as sound propagates 
away from the source, it tends to lose higher-frequency components 
faster than low-frequency components (i.e., low-frequency sounds

[[Page 37584]]

typically propagate longer distances than high-frequency sounds) 
(Diebold et al., 2010). Although higher-frequency components of airgun 
signals have been recorded, it is typically in surface-ducting 
conditions (e.g., DeRuiter et al., 2006; Madsen et al., 2006) or in 
shallow water, where there are advantageous propagation conditions for 
the higher frequency (but low-energy) components of the airgun signal 
(Hermannsen et al., 2015). This should not be of concern because the 
likely behavioral reactions of beaked whales that can result in acute 
physical injury would result from noise exposure at depth (because of 
the potentially greater consequences of severe behavioral reactions). 
In summary, the frequency content of airgun signals is such that beaked 
whales will not be able to hear the signals well (compared to MFA 
sonar), especially at depth where we expect the consequences of noise 
exposure could be more severe.
    Aside from frequency content, there are other significant 
differences between MFA sonar signals and the sounds produced by 
airguns that minimize the risk of severe behavioral reactions that 
could lead to strandings or deaths at sea, e.g., significantly longer 
signal duration, horizontal sound direction, typical fast and 
unpredictable source movement. All of these characteristics of MFA 
sonar tend towards greater potential to cause severe behavioral or 
physiological reactions in exposed beaked whales that may contribute to 
stranding. Although both sources are powerful, MFA sonar contains 
significantly greater energy in the mid-frequency range, where beaked 
whales hear better. Short-duration, high energy pulses--such as those 
produced by airguns--have greater potential to cause damage to auditory 
structures (though this is unlikely for mid-frequency cetaceans, as 
explained later in this document), but it is longer duration signals 
that have been implicated in the vast majority of beaked whale 
strandings. Faster, less predictable movements in combination with 
multiple source vessels are more likely to elicit a severe, potentially 
anti-predator response. Of additional interest in assessing the 
divergent characteristics of MFA sonar and airgun signals and their 
relative potential to cause stranding events or deaths at sea is the 
similarity between the MFA sonar signals and stereotyped calls of 
beaked whales' primary predator: the killer whale (Zimmer and Tyack, 
2007). Although generic disturbance stimuli--as airgun noise may be 
considered in this case for beaked whales--may also trigger 
antipredator responses, stronger responses should generally be expected 
when perceived risk is greater, as when the stimulus is confused for a 
known predator (Frid and Dill, 2002). In addition, because the source 
of the perceived predator (i.e., MFA sonar) will likely be closer to 
the whales (because attenuation limits the range of detection of mid-
frequencies) and moving faster (because it will be on faster-moving 
vessels), any antipredator response would be more likely to be severe 
(with greater perceived predation risk, an animal is more likely to 
disregard the cost of the response; Frid and Dill, 2002). Indeed, when 
analyzing movements of a beaked whale exposed to playback of killer 
whale predation calls, Allen et al., (2014) found that the whale 
engaged in a prolonged, directed avoidance response, suggesting a 
behavioral reaction that could pose a risk factor for stranding. 
Overall, these significant differences between sound from MFA sonar and 
the mid-frequency sound component from airguns and the likelihood that 
MFA sonar signals will be interpreted in error as a predator are 
critical to understanding the likely risk of behaviorally-mediated 
injury due to seismic surveys.
    The available scientific literature also provides a useful contrast 
between airgun noise and MFA sonar regarding the likely risk of 
behaviorally-mediated injury. There is strong evidence for the 
association of beaked whale stranding events with MFA sonar use, and 
particularly detailed accounting of several events is available (e.g., 
a 2000 Bahamas stranding event for which investigators concluded that 
MFA sonar use was responsible; Evans and England, 2001). D'Amico et 
al., (2009) reviewed 126 beaked whale mass stranding events over the 
period from 1950 (i.e., from the development of modern MFA sonar 
systems) through 2004. Of these, there were two events where detailed 
information was available on both the timing and location of the 
stranding and the concurrent nearby naval activity, including 
verification of active MFA sonar usage, with no evidence for an 
alternative cause of stranding. An additional ten events were at 
minimum spatially and temporally coincident with naval activity likely 
to have included MFA sonar use and, despite incomplete knowledge of 
timing and location of the stranding or the naval activity in some 
cases, there was no evidence for an alternative cause of stranding. The 
U.S. Navy has publicly stated agreement that five such events since 
1996 were associated in time and space with MFA sonar use, either by 
the U.S. Navy alone or in joint training exercises with the North 
Atlantic Treaty Organization. The U.S. Navy additionally noted that, as 
of 2017, a 2014 beaked whale stranding event in Crete coincident with 
naval exercises was under review and had not yet been determined to be 
linked to sonar activities (U.S. Navy, 2017). Separately, the 
International Council for the Exploration of the Sea reported in 2005 
that, worldwide, there have been about 50 known strandings, consisting 
mostly of beaked whales, with a potential causal link to MFA sonar 
(ICES, 2005). In contrast, very few such associations have been made to 
seismic surveys, despite widespread use of airguns as a geophysical 
sound source in numerous locations around the world.
    A more recent review of possible stranding associations with 
seismic surveys (Castellote and Llorens, 2016) states plainly that, 
``[s]peculation concerning possible links between seismic survey noise 
and cetacean strandings is available for a dozen events but without 
convincing causal evidence.'' The authors' ``exhaustive'' search of 
available information found ten events worth further investigation via 
a ranking system representing a rough metric of the relative level of 
confidence offered by the data for inferences about the possible role 
of the seismic survey in a given stranding event. Only three of these 
events involved beaked whales. Whereas D'Amico et al., (2009) used a 1-
5 ranking system, in which ``1'' represented the most robust evidence 
connecting the event to MFA sonar use, Castellote and Llorens (2016) 
used a 1-6 ranking system, in which ``6'' represented the most robust 
evidence connecting the event to the seismic survey. As described 
above, D'Amico et al. (2009) found that two events were ranked ``1'' 
and ten events were ranked ``2'' (i.e., 12 beaked whale stranding 
events were found to be associated with MFA sonar use). In contrast, 
Castellote and Llorens (2016) found that none of the three beaked whale 
stranding events achieved their highest ranks of 5 or 6. Of the ten 
total events, none achieved the highest rank of 6. Two events were 
ranked as 5: one stranding in Peru involving dolphins and porpoises and 
a 2008 stranding in Madagascar. This latter ranking can only broadly be 
associated with the survey itself, as opposed to use of seismic 
airguns. An exhaustive investigation of this stranding event, which did 
not involve beaked whales, concluded that use of a high-frequency 
mapping system (12-kHz multibeam echosounder) was the most

[[Page 37585]]

plausible and likely initial behavioral trigger of the event, which was 
likely exacerbated by several site- and situation-specific secondary 
factors. The review panel found that seismic airguns were used after 
the initial strandings and animals entering a lagoon system, that 
airgun use clearly had no role as an initial trigger, and that there 
was no evidence that airgun use dissuaded animals from leaving 
(Southall et al., 2013).
    However, one of these stranding events, involving two Cuvier's 
beaked whales, was contemporaneous with and reasonably associated 
spatially with a 2002 seismic survey in the Gulf of California 
conducted by L-DEO, as was the case for the 2007 Gulf of Cadiz seismic 
survey discussed by Castellote and Llorens (also involving two Cuvier's 
beaked whales). However, neither event was considered a ``true atypical 
mass stranding'' (according to Frantzis [1998]) as used in the analysis 
of Castellote and Llorens (2016). While we agree with the authors that 
this lack of evidence should not be considered conclusive, it is clear 
that there is very little evidence that seismic surveys should be 
considered as posing a significant risk of acute harm to beaked whales 
or other mid-frequency cetaceans. 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.
    Entanglement--Entanglements occur when marine mammals become 
wrapped around cables, lines, nets, or other objects suspended in the 
water column. During seismic operations, numerous cables, lines, and 
other objects primarily associated with the airgun array and hydrophone 
streamers will be towed behind the Langseth near the water`s surface. 
However, we are not aware of any cases of entanglement of mysticetes in 
seismic survey equipment. No incidents of entanglement of marine 
mammals with seismic survey gear have been documented in over 54,000 kt 
(100,000 km) of previous NSF-funded seismic surveys when observers were 
aboard (e.g., Smultea and Holst 2003; Haley and Koski 2004; Holst 2004; 
Smultea et al., 2004; Holst et al., 2005a; Haley and Ireland 2006; SIO 
and NSF 2006b; Hauser et al., 2008; Holst and Smultea 2008). Although 
entanglement with the streamer is theoretically possible, it has not 
been documented during tens of thousands of miles of NSF-sponsored 
seismic cruises or, to our knowledge, during hundreds of thousands of 
miles of industrial seismic cruises. There are a relative few deployed 
devices, and no interaction between marine mammals and any such device 
has been recorded during prior NSF surveys using the devices. There are 
no meaningful entanglement risks posed by the proposed survey, and 
entanglement risks are not discussed further in this document.

Anticipated Effects on Marine Mammal Habitat

    Physical Disturbance--Sources of seafloor disturbance related to 
geophysical surveys that may impact marine mammal habitat include 
placement of anchors, nodes, cables, sensors, or other equipment on or 
in the seafloor for various activities. Equipment deployed on the 
seafloor has the potential to cause direct physical damage and could 
affect bottom-associated fish resources.
    Placement of equipment, such as the heat flow probe in the 
seafloor, could damage areas of hard bottom where direct contact with 
the seafloor occurs and could crush epifauna (organisms that live on 
the seafloor or surface of other organisms). Damage to unknown or 
unseen hard bottom could occur, but because of the small area covered 
by most bottom-founded equipment and the patchy distribution of hard 
bottom habitat, contact with unknown hard bottom is expected to be rare 
and impacts minor. Seafloor disturbance in areas of soft bottom can 
cause loss of small patches of epifauna and infauna due to burial or 
crushing, and bottom-feeding fishes could be temporarily displaced from 
feeding areas. Overall, any effects of physical damage to habitat are 
expected to be minor and temporary.
    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, 
and behavioral responses such as flight or avoidance are the most 
likely effects. However, the reaction of fish to airguns depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. Several 
studies have demonstrated that airgun sounds might affect the 
distribution and behavior of some fishes, potentially impacting 
foraging opportunities or increasing energetic costs (e.g., Fewtrell 
and McCauley, 2012; Pearson et al., 1992; Skalski et al., 1992; 
Santulli et al., 1999; Paxton et al., 2017), though the bulk of studies 
indicate no or slight reaction to noise (e.g., Miller and Cripps, 2013; 
Dalen and Knutsen, 1987; Pena et al., 2013; Chapman and Hawkins, 1969; 
Wardle et al., 2001; Sara et al., 2007; Jorgenson and Gyselman, 2009; 
Blaxter et al., 1981; Cott et al., 2012; Boeger et al., 2006), and 
that, most commonly, while there are likely to be impacts to fish as a 
result of noise from nearby airguns, such effects will be temporary. 
For example, investigators reported significant, short-term declines in 
commercial fishing catch rate of gadid fishes during and for up to five 
days after seismic survey operations, but the catch rate subsequently 
returned to normal (Engas et al., 1996; Engas and Lokkeborg, 2002). 
Other studies have reported similar findings (Hassel et al., 2004). 
Skalski et al., (1992) also found a reduction in catch rates--for 
rockfish (Sebastes spp.) in response to controlled airgun exposure--but 
suggested that the mechanism underlying the decline was not dispersal 
but rather decreased responsiveness to baited hooks associated with an 
alarm behavioral response. A companion study showed that alarm and 
startle responses were not sustained following the removal of the sound 
source (Pearson et al., 1992). Therefore, Skalski et al., (1992) 
suggested that the effects on fish abundance may be transitory, 
primarily occurring during the sound exposure itself. In some cases, 
effects on catch rates are variable within a study, which may be more 
broadly representative of temporary displacement of fish in response to 
airgun noise (i.e., catch rates may increase in some locations and 
decrease in others) than any long-term damage to the fish themselves 
(Streever et al., 2016).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality and, in some studies, fish auditory systems have 
been damaged by airgun noise (McCauley et al., 2003; Popper et al., 
2005; Song et al., 2008). However, in most fish species, hair cells in 
the ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012b. (2012) showed that a TTS of 4-6 dB was recoverable within 
24 hours for one species. Impacts would be most severe when the 
individual fish is close to the source and when the duration of 
exposure is long--both of which are conditions unlikely to occur for 
this survey that is necessarily transient in any given location and 
likely result in brief, infrequent noise exposure to prey species in 
any given area. For this survey, the sound source is constantly moving, 
and most fish would likely avoid the sound source prior to receiving 
sound of sufficient intensity to cause physiological or anatomical 
damage. In addition, ramp-up may

[[Page 37586]]

allow certain fish species the opportunity to move further away from 
the sound source.
    A recent comprehensive review (Carroll et al., 2017) found that 
results are mixed as to the effects of airgun noise on the prey of 
marine mammals. While some studies suggest a change in prey 
distribution and/or a reduction in prey abundance following the use of 
seismic airguns, others suggest no effects or even positive effects in 
prey abundance. As one specific example, Paxton et al., (2017), which 
describes findings related to the effects of a 2014 seismic survey on a 
reef off of North Carolina, showed a 78 percent decrease in observed 
nighttime abundance for certain species. It is important to note that 
the evening hours during which the decline in fish habitat use was 
recorded (via video recording) occurred on the same day that the 
seismic survey passed, and no subsequent data is presented to support 
an inference that the response was long-lasting. Additionally, given 
that the finding is based on video images, the lack of recorded fish 
presence does not support a conclusion that the fish actually moved 
away from the site or suffered any serious impairment. In summary, this 
particular study corroborates prior studies indicating that a startle 
response or short-term displacement should be expected.
    Available data suggest that cephalopods are capable of sensing the 
particle motion of sounds and detect low frequencies up to 1-1.5 kHz, 
depending on the species, and so are likely to detect airgun noise 
(Kaifu et al., 2008; Hu et al., 2009; Mooney et al., 2010; Samson et 
al., 2014). Auditory injuries (lesions occurring on the statocyst 
sensory hair cells) have been reported upon controlled exposure to low-
frequency sounds, suggesting that cephalopods are particularly 
sensitive to low-frequency sound (Andre et al., 2011; Sole et al., 
2013). Behavioral responses, such as inking and jetting, have also been 
reported upon exposure to low-frequency sound (McCauley et al., 2000b; 
Samson et al., 2014). Similar to fish, however, the transient nature of 
the survey leads to an expectation that effects will be largely limited 
to behavioral reactions and would occur as a result of brief, 
infrequent exposures.
    With regard to potential impacts on zooplankton, McCauley et al., 
(2017) found that exposure to airgun noise resulted in significant 
depletion for more than half the taxa present and that there were two 
to three times more dead zooplankton after airgun exposure compared 
with controls for all taxa, within 1 km of the airguns. However, the 
authors also stated that in order to have significant impacts on r-
selected species (i.e., those with high growth rates and that produce 
many offspring) such as plankton, the spatial or temporal scale of 
impact must be large in comparison with the ecosystem concerned, and it 
is possible that the findings reflect avoidance by zooplankton rather 
than mortality (McCauley et al., 2017). In addition, the results of 
this study are inconsistent with a large body of research that 
generally finds limited spatial and temporal impacts to zooplankton as 
a result of exposure to airgun noise (e.g., Dalen and Knutsen, 1987; 
Payne, 2004; Stanley et al., 2011). Most prior research on this topic, 
which has focused on relatively small spatial scales, has showed 
minimal effects (e.g., Kostyuchenko, 1973; Booman et al., 1996; 
S[aelig]tre and Ona, 1996; Pearson et al., 1994; Bolle et al., 2012).
    A modeling exercise was conducted as a follow-up to the McCauley et 
al. (2017) study (as recommended by McCauley et al.,), in order to 
assess the potential for impacts on ocean ecosystem dynamics and 
zooplankton population dynamics (Richardson et al., 2017). Richardson 
et al., (2017) found that for copepods with a short life cycle in a 
high-energy environment, a full-scale airgun survey would impact 
copepod abundance up to three days following the end of the survey, 
suggesting that effects such as those found by McCauley et al., (2017) 
would not be expected to be detectable downstream of the survey areas, 
either spatially or temporally.
    Notably, a recently described study produced results inconsistent 
with those of McCauley et al., (2017). Researchers conducted a field 
and laboratory study to assess if exposure to airgun noise affects 
mortality, predator escape response, or gene expression of the copepod 
Calanus finmarchicus (Fields et al., 2019). Immediate mortality of 
copepods was significantly higher, relative to controls, at distances 
of 5 m or less from the airguns. Mortality one week after the airgun 
blast was significantly higher in the copepods placed 10 m from the 
airgun but was not significantly different from the controls at a 
distance of 20 m from the airgun. The increase in mortality, relative 
to controls, did not exceed 30 percent at any distance from the airgun. 
Moreover, the authors caution that even this higher mortality in the 
immediate vicinity of the airguns may be more pronounced than what 
would be observed in free-swimming animals due to increased flow speed 
of fluid inside bags containing the experimental animals. There were no 
sublethal effects on the escape performance or the sensory threshold 
needed to initiate an escape response at any of the distances from the 
airgun that were tested. Whereas McCauley et al. (2017) reported an SEL 
of 156 dB at a range of 509-658 m, with zooplankton mortality observed 
at that range, Fields et al. (2019) reported an SEL of 186 dB at a 
range of 25 m, with no reported mortality at that distance. Regardless, 
if we assume a worst-case likelihood of severe impacts to zooplankton 
within approximately 1 km of the acoustic source, the brief time to 
regeneration of the potentially affected zooplankton populations does 
not lead us to expect any meaningful follow-on effects to the prey base 
for marine mammals.
    A recent review article concluded that, while laboratory results 
provide scientific evidence for high-intensity and low-frequency sound-
induced physical trauma and other negative effects on some fish and 
invertebrates, the sound exposure scenarios in some cases are not 
realistic to those encountered by marine organisms during routine 
seismic operations (Carroll et al., 2017). The review finds that there 
has been no evidence of reduced catch or abundance following seismic 
activities for invertebrates, and that there is conflicting evidence 
for fish with catch observed to increase, decrease, or remain the same. 
Further, where there is evidence for decreased catch rates in response 
to airgun noise, these findings provide no information about the 
underlying biological cause of catch rate reduction (Carroll et al., 
2017).
    In summary, impacts of the specified activity on marine mammal prey 
species will likely be limited to behavioral responses, the majority of 
prey species will be capable of moving out of the area during the 
survey, a rapid return to normal recruitment, distribution, and 
behavior for prey species is anticipated, and, overall, impacts to prey 
species will be minor and temporary. Prey species exposed to sound 
might move away from the sound source, experience TTS, experience 
masking of biologically relevant sounds, or show no obvious direct 
effects. Mortality from decompression injuries is possible in close 
proximity to a sound, but only limited data on mortality in response to 
airgun noise exposure are available (Hawkins et al., 2014). The most 
likely impacts for most prey species in the survey area would be 
temporary avoidance of the area. The proposed survey would move through 
an area relatively quickly, limiting exposure to multiple impulsive 
sounds. In all cases,

[[Page 37587]]

sound levels would return to ambient once the survey moves out of the 
area or ends and the noise source is shut down and, when exposure to 
sound ends, behavioral and/or physiological responses are expected to 
end relatively quickly (McCauley et al., 2000b). 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. While the potential for disruption of spawning 
aggregations or schools of important prey species can be meaningful on 
a local scale, the mobile and temporary nature of this survey and the 
likelihood of temporary avoidance behavior suggest that impacts would 
be minor.
    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.
    Based on the information discussed herein, we conclude that impacts 
of the specified activity are not likely to have more than short-term 
adverse effects on any prey habitat or populations of prey species. 
Further, any impacts to marine mammal habitat are not expected to 
result in significant or long-term consequences for individual marine 
mammals, or to contribute to adverse impacts on 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 
determinations.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would be by Level B harassment only, primarily in 
the form of behavioral disruption and including through Temporary 
Threshold Shift (TTS) for low frequency cetaceans resulting from 
exposure to sound from seismic airguns. TTS is not expected for all 
other hearing groups and is considered to be unlikely for low frequency 
cetaceans. Given the small size of the Level A harassment isopleths 
(28.6 m for LF cetaceans and less than one meter for all other species) 
and the anticipated effectiveness of the mitigation measures (i.e., 
shutdown, ramp-up, etc.) discussed in detail below in Proposed 
Mitigation section, Level A harassment is neither anticipated nor 
proposed to be authorized.
    As described previously, no serious injury or mortality is 
anticipated or proposed to be authorized for this activity. Below we 
describe how the proposed take numbers are estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and (4) and 
the number of days of activities. We note that while these basic 
factors can contribute to a basic calculation to provide an initial 
prediction of takes, additional information that can qualitatively 
inform take estimates is also sometimes available (e.g., previous 
monitoring results or average group size). Below, we describe the 
factors considered here in more detail and present the proposed take 
estimate.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment

[[Page 37588]]

when exposed to underwater anthropogenic noise above root-mean-squared 
pressure received levels (RMS SPL) of 120 dB (referenced to 1 
micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile-
driving, drilling) and above RMS SPL 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 survey includes the use of impulsive seismic 
sources (e.g., GI-airgun) and therefore the 160 dB re 1 [mu]Pa (rms) 
criteria is applicable for analysis of Level B harassment.
    Level A harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). L-DEO's 
proposed survey includes the use of impulsive and intermittent sources.
    For more information, see NMFS' 2018 Technical Guidance, which may 
be accessed at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss 
coefficient.
    The proposed 2D survey would acquire data using a 2 GI-airgun 
cluster with a total discharge volume of 90 in\3\ at a maximum tow 
depth of 2-4 m. L-DEO model results are used to determine the 160 dB 
rms radius for the 2-GI airgun array in deep water (>1000 m) down to a 
maximum depth of 2000 m, as animals are generally not anticipated to 
dive below 2000 m (Costa and Williams, 1999). Received sound levels for 
the two 45 in\3\ GI airguns have been predicted by L-DEO's model 
(Diebold et al., 2010) as a function of distance from the airguns. This 
modeling approach 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 a 36-airgun array at a tow depth of 6 m have been reported 
in deep water (~1600 m), intermediate water depth on the slope (~600-
1100 m), and shallow water (~50) 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 mitigation radii, as at those sites 
the calibration hydrophone was located at a roughly constant depth of 
350-500 m, which may not intersect all the sound pressure level (SPL) 
isopleths at their widest point from the sea surface down to the 
maximum relevant water depth (~2000 m) for marine mammals. At short 
ranges, where the direct arrivals dominate and the effects of seafloor 
interactions are minimal, the data recorded at the deep sites are 
suitable for comparison with modeled levels at the depth of the 
calibration hydrophone. At longer ranges, the comparison with the 
mitigation model--constructed from the maximum SPL through the entire 
water column at varying distances from the airgun array--is the most 
relevant.
    In deep and intermediate-water depths, comparisons at short ranges 
between sound levels for direct arrivals recorded by the calibration 
hydrophone and model results for the same array tow depth are in good 
agreement (Fig. 12 and 14 in Appendix H of L-DEO's PEIS). Consequently, 
isopleths falling within this domain can be predicted reliably by the 
L-DEO model, although they may be imperfectly sampled by measurements 
recorded at a single depth. At greater distances, the calibration data 
show that seafloor-reflected and sub-seafloor-refracted arrivals 
dominate, whereas the direct arrivals become weak and/or incoherent. 
Aside from local topography effects, the region around the critical 
distance is where the observed levels rise closest to the mitigation 
model curve. However, the observed sound levels are found to fall 
almost entirely below the mitigation model curve. Thus, analysis of the 
Gulf of Mexico calibration measurements demonstrate that although 
simple, the L-DEO model is a robust tool for conservatively estimating 
isopleths and the deep water radii obtained from model results down to 
a maximum water depth of 2000 m.
    A recent retrospective analysis of acoustic propagation of R/V 
Langseth sources in a coastal/shelf environment from the Cascadia 
Margin off Washington suggests that predicted (modeled) radii (using a 
similar approach) for R/V Langseth sources were 2-3 times larger than 
measured in shallow water (Crone et al., 2014). Similarly, data 
collected by Crone et al. (2017) during a survey off New Jersey in 2014 
and 2015 confirmed that in situ measurements and estimates of the 160- 
and 180-dB distances collected by R/V Langseth hydrophone streamer were 
2-3 times smaller than the predicted operational mitigation radii. Five 
separate comparisons conducted of the L-DEO model with in situ received 
level have confirmed that the L-DEO model generated conservative 
mitigation zones, resulting in significantly larger zones.
    The proposed surveys would acquire data with two 45 in\3\ GI funs 
at a tow depth of 2-4 m. As the entire survey occurs in deep water 
(>1000 m), L-DEO used the deep-water radii obtained from the model 
results explained above down to a maximum warter depth of 2000 m (see 
Figure A-1 in L-DEO's application). The estimated distances to the 
Level B harassment isopleth for the proposed survey are shown in Table 
3. The acoustic propagation modeling methodologies are described in 
greater detail in L-DEO's IHA application.

  Table 3--Predicted Radial Distances to Isopleths Corresponding to the
                      Level B Harassment Threshold
                      [160 dB re 1[micro]Pa (rms)]
------------------------------------------------------------------------
                                                    Predicted  distances
                                                     (m) to  a received
     Airgun configuration        Water depth  (m)   sound level  of 160
                                                     dB re 1 [mu]Parms
------------------------------------------------------------------------
Two 45-in\3\ GI guns..........            >1,000                    553
------------------------------------------------------------------------


[[Page 37589]]

    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 PGS Nucleus source modeling 
software program and the NMFS User Spreadsheet, described below. The 
acoustic thresholds for impulsive sounds (e.g., airguns) contained in 
the Technical Guidance were presented as dual metric acoustic 
thresholds using both SELcum and peak sound pressure metrics 
(NMFS 2018). As dual metrics, NMFS considers onset of PTS (Level A 
harassment) to have occurred when either one of the two metrics is 
exceeded (i.e., metric resulting in the largest isopleth). The 
SELcum metric considers both level and duration of exposure, 
as well as auditory weighting functions by marine mammal hearing group. 
In recognition of the fact that the requirement to calculate Level A 
harassment ensonified areas could be more technically challenging to 
predict due to the duration component and the use of weighting 
functions in the new SELcum thresholds, NMFS developed an 
optional User Spreadsheet that includes tools to help predict a simple 
isopleth that can be used in conjunction with marine mammal density or 
occurrence to facilitate the estimation of take numbers.
    In order to more realistically incorporate the Technical Guidance's 
weighting functions over the seismic array's full acoustic band, 
unweighted spectrum data for the Langseth's airgun array (modeled in 1 
Hz bands) was used to make adjustments (dB) to the unweighted spectrum 
levels, by frequency, according to the weighting functions for each 
relevant marine mammal hearing group. These adjusted/weighted spectrum 
levels were then converted to pressures ([micro]Pa) in order to 
integrate them over the entire broadband spectrum, resulting in 
broadband weight 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 (2.32 m/s) and shot intervals (every 
2.69 s) specific to the planned survey, potential radial distances to 
auditory injury zones were then calculated for SELcum 
thresholds. Outputs from the User Spreadsheet in the form of estimated 
distance to Level A harassment isopleths for the survey are shown in 
Table 4. NMFS considers onset of PTS (Level A harassment) to have 
occurred when either one of the dual metrics (SELcum and 
Peakflat) is exceeded (i.e., metric resulting in the largest 
isopleth).

                            Table 4--Modeled Radial Distances (m) to Isopleths Corresponding to Level A Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                 Level A harassment zones (m)
                          Source  (volume)                          ------------------------------------------------------------------------------------
                                                                            LF               MF               HF             Phocid          Otariid
--------------------------------------------------------------------------------------------------------------------------------------------------------
Two 45 cu in GI guns...............................................            28.6                0              0.1              0.3                0
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used (e.g., stationary receiver with no vertical or horizontal 
movement in response to the acoustic source), isopleths produced may be 
overestimates to some degree, which will ultimately result in some 
degree of overestimation of Level A harassment. However, these tools 
offer the best way to predict appropriate isopleths when more 
sophisticated modeling methods are not available. NMFS continues to 
develop ways to quantitatively refine these tools and will 
qualitatively address the output where appropriate. For mobile sources, 
such as the proposed seismic survey, the User Spreadsheet predicts the 
closest distance at which a stationary animal would not incur PTS if 
the sound source traveled by the animal in a straight line at a 
constant speed.
    Auditory injury for all species is unlikely to occur given the 
small modeled zones of injury (estimated zone less than 30 m for low-
frequency cetaceans and near zero for all other species). Additionally, 
animals are expected to have aversive/compensatory behavior in response 
to the activity (Nachtigall et al., 2018) further limiting the 
likelihood of auditory injury for all species. L-DEO did not request 
authorization of take by Level A harassment, and no take by Level A 
harassment is proposed for authorization by NMFS.

Marine Mammal Occurrence

    In this section we provide information about the occurrence of 
marine mammals, including density or other relevant information, which 
will inform the take calculations.
    The U.S. Navy (USN) primarily use the Southwest Fishery Science 
Center (SWFSC) habitat-based cetacean density models to develop a 
marine species density database for the Northwest Training and Testing 
Study Area, which encompasses the proposed survey area (USN 2019). For 
species where density spatial modeling was unavailable, other data 
sources were used. The USN marine species density database is currently 
the most comprehensive density data set available for the California 
Current Ecosystem (CCE) which encompasses waters off the coast of 
California, Oregon, and Washington. However, GIS data layers are 
currently unavailable for this database; thus, in this analysis the USN 
data were only used for species for which density data were not 
available from an alternative spatially-explicit model (i.e., minke, 
sei, and killer whales, Kogia spp., and pinnipeds).
    For most pinnipeds, L-DEO used the highest densities for spring, 
summer, or fall from USN (2019), but corrected the estimates by 
projecting the most recent population growth/updated population 
estimates to 2022, when available. This same approach was used by NMFS 
for previous L-DEO surveys (e.g,. Northeast Pacific Ocean Survey (85 FR 
19580; April 7, 2020)) in the region in 2021. For California sea lions, 
spring densities from USN (2019) were used directly, the density for 
the `40-70 km from shore' distance band was used for the Oregon survey 
region, and the density for the `70-450 km from shore' distance band 
was used for other survey regions. For the northern fur seal, the 
density for the spring for the `up to 70 km from shore' distance band 
was used for the Oregon survey region, and the spring density for the 
`>130 km from shore' distance band was used for the other survey 
regions. For the Guadalupe fur seal and Steller sea lion, summer 
densities for the `200 m isobath to 300 km from shore' were used. For 
the gray whale, the summer/fall density for the `10-47 km from shore' 
distance band (USN 2019) was used for the Oregon survey region and

[[Page 37590]]

a density of zero was used for all other survey regions. For killer 
whales, the annual density for all stocks occurring offshore was used 
from USN (2019).
    Spatially-explicit density data from summer/fall from the NOAA 
CetSound website (NOAA 2022) were used for most other species (i.e., 
humpback, blue, fin, sperm, Baird's, beaked, and other small beaked 
whales; striped, short-beaked common, Pacific white-sided, Risso's, and 
northern right whale dolphins; and Dall's porpoise. CetMap (https://cetsound.noaa.gov/cda) provides output of summer/fall habitat-based 
density models for cetaceans in the CCE (Becker et al., 2020) in the 
form of GIS layers; these were used to calculate takes in the survey 
area. The density estimates were available in the form of a GIS grid 
with each cell in the grid measuring ~7 km east-west by 10 km north-
south. This grid was intersected with a GIS layer of the area expected 
to be ensonified to >160 dB SPL from the survey area. North, west, and 
south boundaries are based on overlap/intersection with geographic 
extents of all four combined survey regions; eastern grid coverage 
limit was defined by inclusion of cells that contained >25 percent 
overlap with the angled boundary of the survey area polygon. The 
densities from all grid cells overlapping the ensonified areas were 
averaged to calculate an average species-specific density for each 
species (Table 5).

                          Table 5--Modeled Marine Mammal Density Values and Daily Ensonified Area for L-DEO's Proposed Survey *
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                           Daily
                    Species                      Density  (#/km\2\)     ensonified       Number of                          Source
                                                                       area  (km\2\)   seismic days
--------------------------------------------------------------------------------------------------------------------------------------------------------
LF Cetaceans:
    Humpback whale............................              0.000464             221               6  Becker et al. (2020).
    Blue whale................................              0.000226             221               6  Becker et al. (2020).
    Fin whale.................................               0.00241             221               6  Becker et al. (2020).
    Sei whale.................................                0.0004             221               6  USN (2019).
    Minke whale...............................                0.0013             221               6  USN (2019).
MF Cetaceans:
    Sperm whale...............................              0.002859             221               6  Becker et al. (2020).
    Baird's beaked whale......................              0.000407             221               6  Becker et al. (2020).
    Small beaked whale........................              0.002446             221               6  Becker et al. (2020).
    Striped dolphin...........................              0.002095             221               6  Becker et al. (2020).
    Short-beaked common dolphin...............              0.004845             221               6  Becker et al. (2020).
    Pacific white-sided dolphin...............              0.059902             221               6  Becker et al. (2020).
    Northern right-whale dolphin..............              0.049535             221               6  Becker et al. (2020).
    Risso's dolphin...........................              0.009917             221               6  Becker et al. (2020).
    Killer whale..............................               0.00092             221               6  USN (2019).
HF Cetaceans:
    Pygmy/dwarf sperm whale...................               0.00163             221               6  USN (2019).
    Dall's porpoise...........................              0.093613             221               6  Becker et al. (2020).
Otariid Seals:
    Northern fur seal.........................   * 0.036115/0.032983             221               6  USN (2019).
    Guadalupe fur seal........................               0.02945             221               6  USN (2019).
    California sea lion.......................       * 1.2951/0.0714             221               6  USN (2019).
    Steller sea lion..........................              0.002573             221               6  USN (2019).
Phocid Seal:
    Northern elephant seal....................              0.043301             221               6  USN (2019).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Species in this table differ slightly from those included in L-DEO's application as NMFS has determined that their occurrence in the survey area is
  rare and unlikely to be encountered. For more information, please see the Description of Marine Mammals in the Area of Specified Activity section of
  this notice.
** Two different densities were used depending on water depth/distance from shore.

Take Estimation

    Here we describe how the information provided above is synthesized 
to produce a quantitative estimate of the take that is reasonably 
likely to occur and proposed for authorization. In order to estimate 
the number of marine mammals predicted to be exposed to sound levels 
that would result in Level B harassment, radial distances from the 
airgun array to the predicted isopleth corresponding to the 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 
B harassment threshold. The distance for the 160-dB threshold (based on 
L-DEO model results) was used to draw a buffer around the area expected 
to be ensonified (i.e., the survey area). The ensonified areas were 
then increased by 25 percent to account for potential delays, which is 
the equivalent to adding 25 percent to the proposed line km to be 
surveyed. The density for each species in Table 5 were then multiplied 
by the daily ensonified areas expected to be ensonified, increased by 
25 percent, and then multiplied by the number of survey days (6) to 
estimate the Level B takes.
    The marine mammals predicted to occur within these respective 
areas, based on the estimated densities, are assumed to be incidentally 
taken. Estimated exposures for the proposed survey are shown in Table 
6.

[[Page 37591]]



         Table 6--Estimated Take by Level B Harassment, and Percentage of Marine Mammal Stock Population
----------------------------------------------------------------------------------------------------------------
                                                                Take by level B
                                               Estimated take      harassment          Stock        Percent of
           Species               MMPA stock      by Level B       proposed for       abundance      MMPA stock
                                                 harassment      authorization
----------------------------------------------------------------------------------------------------------------
Humpback whale \a\..........  California/                   1              \d\ 2           4,973            0.04
                               Oregon
                               Washington.
Blue whale..................  Eastern North                 0              \d\ 2           1,898            0.11
                               Pacific.
Fin whale...................  California/                   4                  4          11,065            0.04
                               Oregon
                               Washington.
Sei whale...................  Eastern North                 1              \d\ 2             519            0.39
                               Pacific.
Minke whale.................  California/                   2                  2             915            0.22
                               Oregon
                               Washington.
Sperm whale.................  California/                   5              \d\ 7           1,997            0.35
                               Oregon
                               Washington.
Baird's beaked whale........  California/                   1              \d\ 9           1,363            0.66
                               Oregon
                               Washington.
Small beaked whale \b\......  California/                   4                  4           3,044            0.13
                               Oregon
                               Washington.
Striped dolphin.............  California/                   3             \d\ 46          29,988            0.15
                               Oregon
                               Washington.
Common dolphin..............  California/                   8            \d\ 179       1,056,308            0.02
                               Oregon
                               Washington.
Pacific white-sided dolphin.  California/                  99                 99          34,998            0.28
                               Oregon
                               Washington.
Northern right-whale dolphin  California/                  82                 82          29,285            0.28
                               Oregon
                               Washington.
Risso's dolphin.............  California/                  16             \d\ 22           6,336            0.35
                               Oregon
                               Washington.
Killer whale................  West Coast                    2              \d\ 7             349            0.00
                               Transient.
                              North Pacific                                                  300            0.00
                               Offshore.
Pygmy/dwarf sperm whale.....  California/                   3                  3           4,111            0.07
                               Oregon
                               Washington.
Dall's porpoise.............  California/                 155                155          16,498            0.94
                               Oregon
                               Washington.
Northern fur seal \c\.......  Eastern Pacific              17                 17         626,618            0.00
                              California.....                                            530,376            0.00
Guadalupe fur seal..........  Mexico.........              49                 49          34,187            0.14
California sea lion.........  United States..               9                  9         257,606            0.00
Steller sea lion............  Eastern........               4                  4          43,201            0.01
Northern elephant seal......  California                   62                 62           5,122            1.21
                               Breeding.
----------------------------------------------------------------------------------------------------------------
\a\ Takes are allocated among the three DPSs in the area based on Wade 2021 (Oregon: 42 percent Central America
  DPS, 58 percent Mexico DPS; Washington: 6 percent Central America DPS, 25 percent Mexico DPS, 69 percent
  Hawaii DPS).
\b\ Proposed takes include one each of Blainville's beaked whale, Stejneger's beaked whale, Cuvier's beaked
  whale, and Hubbs' beaked whale (see Appendix B of L-DEO's application for more information).
\c\ In cases where multiple stocks are being affected, for the purposes of calculating the percentage of the
  stock impacted, the take is being analyzed as if all proposed takes occurred within each stock.
\d\ Proposed take increased to mean group size from Barlow (2016).

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks, and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers 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.
    L-DEO 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 
proposed mitigation measures based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, L-DEO proposed to implement mitigation 
measures for marine mammals. Mitigation measures that would be adopted 
during the planned survey include, but are not limited to: (1) Vessel 
speed or course alteration, provided that doing so would not compromise 
operation safety requirements. (2) GI-airgun shut down within EZs, and 
(3) ramp-up procedures.

Vessel-Based Visual Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual protected species observers (PSOs)) to scan the 
ocean surface visually for the presence of marine mammals. The area to 
be scanned visually includes primarily the exclusion zone, within which 
observation of certain marine mammals requires shutdown of the acoustic 
source, 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-start clearance (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

[[Page 37592]]

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 
100 m exclusion zone measured from the edges of the airgun array. 
Visual monitoring of the exclusion zone and adjacent waters is intended 
to establish and, when visual conditions allow, maintain zones around 
the sound source that are clear of marine mammals, thereby reducing or 
eliminating the potential for injury and minimizing the potential for 
more severe behavioral reactions for animals occurring closer to the 
vessel. Visual monitoring of the buffer zone is intended to (1) provide 
additional protection to na[iuml]ve marine mammals that may be in the 
area during pre-clearance, and (2) during airgun use, aid in 
establishing and maintaining the exclusion zone by altering the visual 
observer and crew of marine mammals that are outside of, but may 
approach and enter, the exclusion zone.
    L-DEO must use independent, dedicated, trained visual PSOs, meaning 
that the PSOs must be employed by a third-party observer provider, must 
not have tasks other than to conduct observational effort, collect 
data, and communicate with and instruct relevant vessel crew with 
regard to the presence of protected species and mitigation 
requirements, and must have successfully completed an approved PSO 
training course. PSO resumes shall be provided to NMFS for approval.
    At least one visual PSO must have a minimum of 90 days at-sea 
experience working in that role during a shallow penetration or low-
energy survey, with no more than 18 months elapsed since the conclusion 
of the at-sea experience. One 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 the 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 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 ramp-up 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 must coordinate to ensure 360 degree 
visual coverage around the vessel from the most appropriate observation 
posts, and must 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) shall be communicated to 
the operator to prepare for the potential shutdown of the acoustic 
source.
    During use of the airgun, detections of marine mammals within the 
buffer zone (but outside the exclusion zone) should be communicated to 
the operator to prepare for the potential shutdown of the acoustic 
source. Visual PSOs will immediately communicate all observations to 
the on duty acoustic PSO(s), including any determination by the PSO 
regarding species identification, distance, and bearing and the degree 
of confidence in the determination. Any observations of marine mammals 
by crew members shall be relayed to the PSO team. During good 
conditions (e.g., daylight hours; Beaufort sea state (BSS) 3 or less), 
visual PSOs shall conduct observations when the acoustic source is not 
operating for comparison of sightings 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.

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 outcome, e.g., auditory injury, disruption of 
critical behaviors. The PSOs would establish a minimum EZ with a 100 m 
radius with an additional 100 m buffer zone (total of 200 m). The 200m 
zone would be based on radial distance from the edge of the airgun 
array (rather than being based on the center of the array or around the 
vessel itself). With certain exceptions (described below), if a marine 
mammal appears within or enters this zone, the acoustic source would be 
shut down.
    The 100 m EZ, with additional 100 m buffer zone, 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 100 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 100 m is regularly attainable for PSOs using the naked eye 
during typical conditions.
    An extended 500 m exclusion zone must be established for all beaked 
whales, dwarf and pygmy sperm whales, killer whales, a large whale with 
a calf, and groups of six or more large whales during all survey 
effort. No buffer zone is required.

Pre-Clearance and Ramp-Up

    Ramp-up (sometimes referred to as ``soft start'') is the gradual 
and systematic increase of emitted sound levels from an airgun array. 
Ramp-up would begin with one GI airgun 45 cu in first being activated, 
followed by the second after 5 minutes. The intent of pre-clearance 
observation (30 minutes) is to ensure no marine mammals are observed 
within the buffer zone prior to the beginning of ramp-up. During pre-
clearance is the only time observations of marine mammals in the buffer 
zone would prevent operations (i.e., the beginning of ramp-up). The 
intent of ramp-up is to warn 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 are activated and the full volume is achieve, 
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 PSOs time to monitor the exclusion and buffer

[[Page 37593]]

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 minutes 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 pinnipeds, and 30 minutes for Mysticetes and all other 
odontocetes, including sperm whales, pygmy sperm whales, dwarf sperm 
whales, beaked whales, pilot whales, killer whales, Risso's dolphin);
     PSOs must monitor the exclusion and buffer zones during 
ramp-up, and ramp-up must cease and the source must be shut down upon 
detection of a marine mammal within the applicable exclusion zone. Once 
ramp-up has begun, detections of marine mammals within the buffer zone 
do not require shutdown, but such observation shall be communicated to 
the operator to prepare for the potential shutdown.
     If the acoustic source is shut down for brief periods 
(i.e., less than 30 minutes) for reasons other than that described for 
shutdown (e.g., mechanical difficulty), it may be activated again 
without ramp-up if PSOs have maintained constant observation and no 
detections of marine mammals have occurred within the applicable 
exclusion zone. For any longer shutdown, pre-start clearance 
observation and ramp-up are required. For any shutdown at night or in 
periods of poor visibility (e.g., BSS 4 or greater), ramp-up is 
required, but if the shutdown period was brief and constant observation 
was maintained, pre-start clearance watch is not required.
     Testing of the acoustic source involving all elements 
requires ramp-up. Testing limited to individual source elements or 
strings does not require ramp-up but does require pre-start clearance 
watch.

Shutdown

    The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array. Any PSO on 
duty will have the authority to delay the start of survey operations or 
to call for shutdown of the acoustic source if a marine mammal is 
detected within the applicable 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 commands are conveyed swiftly while allowing PSOs to maintain 
watch. When both visual and acoustic PSOs are on duty, all detections 
will be immediately communicated to the remainder of the on-duty PSO 
team for potential verification of visual observations by the acoustic 
PSO or of acoustic detections by visual PSOs. When the airgun array is 
active (i.e., anytime one or more airguns is active, including during 
ramp-up) and (1) a marine mammal appears within or enters the 
applicable 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.
    Following a shutdown, airgun activity would not resume until the 
marine mammal has clear the EZ. The animal would be considered to have 
cleared the EZ if it is visually observed to have departed the EZ, or 
it has not been seen within the EZ for 15 minutes in the case of small 
odontocetes and pinnipeds, and 30 minutes for Mysticetes and all other 
odontocetes, including sperm whales, beaked whales, pilot whales, 
killer whales, and Risso's dolphin) with no further observation of the 
marine mammal(s).
    The shutdown requirement can be waived for small dolphins if an 
individual is visually detected and localized within an exclusion zone. 
As defined here, the small dolphin group is intended to encompass those 
members of the Family Delphinidae most likely to voluntarily approach 
the source vessel for purposes of interacting with the vessel and/or 
airgun array (e.g., bow riding). This exception to the shutdown 
requirement applies solely to specific genera of small dolphins-
Delphinus, Stenella, and Lissodelphis.
    We propose this small dolphin exception because shutdown 
requirements for small dolphins under all circumstances represent 
practicability concerns without likely commensurate benefits for the 
animals in question. Small dolphins are generally the most commonly 
observed marine mammals in the specific geographic region and would 
typically be the only marine mammals likely to intentionally approach 
the vessel. As described above, auditory injury is extremely unlikely 
to occur for mid-frequency cetaceans (e.g., delphinids), as this group 
is relatively insensitive to sound produced at the predominant 
frequencies in an airgun pulse while also having a relatively high 
threshold for the onset of auditory injury (i.e., permanent threshold 
shift).
    A large body of anecdotal evidence indicates that small dolphins 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinids (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 delphinids) are no more likely to incur 
auditory injury than are small dolphins, they are much less likely to 
approach vessels. Therefore, retaining a shutdown requirement for large 
delphinids would not have similar impacts in terms of either 
practicability for the applicant or corollary increase in sound energy 
output and time on the water. We do anticipate some benefit for a 
shutdown requirement for large delphinids in that it simplifies 
somewhat the total range of decision-making for PSOs and may preclude 
any potential for physiological effects other than to the auditory 
system as well as some more severe behavioral reactions for any such 
animals in close proximity to the source vessel. Visual PSOs shall use 
best professional judgment in making the decision to call for a 
shutdown if there is uncertainty regarding identification (i.e., 
whether the observed marine mammal(s) belongs to one of the delphinid 
genera for which shutdown is waived or one of the species with a larger 
exclusion zone).
    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 a clearance period (15 minutes for 
small odontocetes and pinnipeds, and 30 minutes for mysticetes and all 
other odontocetes, including sperm whales, beaked whales, pilot whales, 
killer whales, and Risso's

[[Page 37594]]

dolphin) with no further observation of the marine mammal(s).
    L-DEO must implement shutdown if a marine mammal species for which 
take was not authorized, or a species for which authorization was 
granted but the takes have been met, approaches the Level B harassment 
zones.

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 mysticetes);
    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 area. This recommendation does not apply to any vessel towing 
gear.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the proposed mitigation measures 
provide the means of effecting the least practicable impact on the 
affected species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

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

Vessel-Based Visual Monitoring

    As described above, PSO observations would take place during 
daytime airgun operations. During seismic operations, at least three 
visual PSO would be based aboard the Langseth. Two visual PSOs would be 
on duty at all time during daytime hours. Monitoring shall be conducted 
in accordance with the following requirements:
     PSOs shall be independent, dedicated and trained and must 
be employed by a third-party observer provider;
     PSOs shall have no tasks other than to conduct visual 
observational effort, 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);
     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

[[Page 37595]]

     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.
    PSOs must use standardized data collection forms, whether hard copy 
or electronic. PSOs must record detailed information about any 
implementation of mitigation requirements, including the distance of 
animals to the acoustic source and description of specific actions that 
ensued, the behavior of the animal(s), any observed changes in behavior 
before and after implementation of mitigation, and if shutdown was 
implemented, the length of time before any subsequent ramp-up of the 
acoustic source. If required mitigation was not implemented, PSOs 
should record a description of the circumstances. At a minimum, the 
following information must be recorded:
     Vessel name and call sign;
     PSO names and affiliations;
     Date and participants of PSO briefings (as discussed in 
General Requirement);
     Dates of departure and return to port with port name;
     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-start clearance, ramp-up, shutdown, testing, shooting, ramp-
up completion, end of operations, streamers, etc.).
    The following information should be recorded upon visual 
observation of any marine mammal:
     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.

Reporting

    L-DEO must 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. A final 
report must be submitted within 30 days following resolution of any 
comments on the draft report. 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.
    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 in the IHA. A final 
report must be submitted within 30 days following resolution of any 
comments on the draft report.

Reporting Injured or Dead Marine Mammals

    Discovery of injured or dead marine mammals--In the event that 
personnel involved in survey activities covered by the authorization 
discover an injured or dead marine mammal, the L-DEO shall report the 
incident to the Office of Protected Resources (OPR), NMFS and to the 
NMFS 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;

[[Page 37596]]

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

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

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

Reporting Species of Concern

    To support NMFS's goal of improving our understanding of occurrence 
of marine mammal species or stocks in the area (e.g., presence, 
abundance, distribution, density), L-DEO will immediately report 
observations of Southern Resident killer whales or North Pacific right 
whales to OPR, NMFS. Although, the likelihood of encountering either 
species is considered to be rare and unexpected.

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 impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), 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' 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 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, the discussion of our analysis applies to all 
the species listed in Table 6, given that the anticipated effects of 
this activity on these different marine mammal stocks are expected to 
be similar, except where a species- or stock-specific discussion is 
warranted. NMFS does not anticipate that serious injury or mortality 
would occur as a result from low-energy surveys, even in the absence of 
mitigation, and no serious injury or mortality is proposed to be 
authorized. As discussed in the Potential Effects of Specified 
Activities on Marine Mammals and their Habitat section, non-auditory 
physical effects and vessel strike are not expected to occur. NMFS 
expects that all potential take would be in the form of Level B 
behavioral harassment in the form of temporary avoidance of the area or 
decreased

[[Page 37597]]

foraging (if such activity was occurring), responses that are 
considered to be of low severity, and with no lasting biological 
consequences (e.g., Southall et al., 2007, 2021). TTS is not expect for 
most hearing groups (HF, MF, otariids and phocids) and is considered to 
be highly unlikely for LF cetaceans. Even repeated Level B harassment 
of some small subset of an overall stock is unlikely to result in any 
significant realized decrease in viability for the affected 
individuals, and thus would not result in any adverse impact to the 
stock as a whole. As described above, Level A harassment is not 
expected to occur given the estimated small size of the Level A 
harassment zones.
    In addition to being temporary, the maximum expected Level B 
harassment zone around the survey vessel is 553 m. Therefore, the 
ensonified area surrounding the vessel is relatively small compared to 
the overall distribution of animals in the area and their use of the 
habitat. Feeding behavior is not likely to be significantly impacted as 
prey species are mobile and are broadly distributed throughout the 
survey area; 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 short duration (6 days) and temporary 
nature of the disturbance and 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 entire U.S. West Coast within 47 km of the coast is a BIA for 
migrating gray whale potential presence January to July and October to 
December. The BIA for northbound gray whale migration is broken into 
two phases, Phase A (within 8 km of shore) and Phase B (within 5 km of 
shore), which are active from January to July and March to July, 
respectively. The BIA for southbound migration includes waters within 
10 km of shore and is active from October to March. All planned survey 
areas are outside of all gray whale BIAs and no takes of gray whales 
are proposed for authorization. There are also two humpback whale 
feeding BIAs (Stonewall and Heceta Bank) adjacent to the survey area, 
however no overlap occurs between the survey area and the BIAs. There 
are no rookeries, mating or calving grounds known to be biologically 
important to marine mammals within the proposed survey area.
    Critical habitat for the Mexico and Central America DPSs of 
humpback whales has been established along the U.S. West Coast (86 FR 
21082; May 5, 2021), and NMFS has expanded the Southern Resident killer 
whale critical habitat to include coastal waters of Washington, Oregon, 
and California (86 FR 41668; August 2, 2021). No part of L-DEO's 
proposed seismic survey will occur in or near these critical habitats.
    No permanent hearing impairment (Level A harassment) is anticipated 
or proposed to be authorized. Authorized takes of killer whales is 
expected to comprise almost entirely of the West Coast Transient and/or 
North Pacific Offshore stocks as Southern Resident killer whales are 
typically confined to coastal and inland waters. Therefore take of 
Southern Resident killer whales is unlikely given the far offshore 
location of the proposed survey, and no take of Southern Resident 
killer whales is proposed for authorization.
    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 any of the species 
or stocks through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or 
authorized;
     The proposed activity is temporary and of relatively short 
duration (6 days);
     The anticipated impacts of the proposed activity on marine 
mammals would be temporary behavioral changes due to avoidance of the 
area around the vessel;
     No take by Level A harassment is proposed for 
authorization;
     The availability of alternative 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 is 
readily abundant;
     The potential adverse effects on fish or invertebrate 
species that serve as prey species for marine mammals from the proposed 
survey would be temporary and spatially limited, and impacts to marine 
mammal foraging would be minimal; and
     The proposed mitigation measures, including visual, 
shutdowns, and enhanced measures for areas of biological importance 
(e.g., additional monitoring vessel, daylight operations only) are 
expected to minimize potential impacts to marine mammals (both amount 
and severity).
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    The amount of take NMFS proposes to authorize is below one third of 
the estimated stock abundance for all species (in fact, take of 
individuals is less than ten percent of the abundance of the affected 
stocks, see Table 6). This is likely a conservative estimate because we 
assume all takes are of different individual animals, which is likely 
not the case. Some individuals may be encountered multiple times in a 
day, but PSOs would count them as separate individuals if they cannot 
be identified.
    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 would 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 
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.

Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal

[[Page 37598]]

agency insure that any action it authorizes, funds, or carries out is 
not likely to jeopardize the continued existence of any endangered or 
threatened species or result in the destruction or adverse modification 
of designated critical habitat. To ensure ESA compliance for the 
issuance of IHAs, NMFS consults internally whenever we propose to 
authorize take for endangered or threatened species, in this case with 
the ESA Interagency Cooperation Division within NMFS' Office of 
Protected Resources (OPR).
    NMFS is proposing to authorize take of blue whales, fin whales, sei 
whales, sperm whales, Central America DPS humpback whales, Mexico DPS 
humpback whales, and Guadalupe fur seal, which are listed under the 
ESA. The NMFS OPR Permits and Conservation Division has requested 
initiation of Section 7 consultation with the NMFS OPR ESA Interagency 
Cooperation Division for the issuance of this IHA. NMFS will conclude 
the ESA consultation prior to reaching a determination regarding the 
proposed issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to L-DEO for conducting geophysical surveys in the 
Northeast Pacific Ocean during Summer 2022, 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/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the proposed 
survey. We also request comment on the potential renewal of this 
proposed IHA as described in the paragraph below. Please include with 
your comments any supporting data or literature citations to help 
inform decisions on the request for this IHA or a subsequent renewal 
IHA.
    On a case-by-case basis, NMFS may issue a one-time, one-year 
renewal IHA following notice to the public providing an additional 15 
days for public comments when (1) up to another year of identical or 
nearly identical activities as described in the Description of Proposed 
Activities section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activities section of this 
notice would not be completed by the time the IHA expires and a renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed renewal IHA effective date (recognizing that the 
renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA).
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take).
    (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 16, 2022.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2022-13328 Filed 6-22-22; 8:45 am]
BILLING CODE 3510-22-P