[Federal Register Volume 85, Number 67 (Tuesday, April 7, 2020)]
[Notices]
[Pages 19580-19634]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-07289]



[[Page 19579]]

Vol. 85

Tuesday,

No. 67

April 7, 2020

Part II





 Department of Commerce





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National Oceanic and Atmospheric Administration





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

  Federal Register / Vol. 85, No. 67 / Tuesday, April 7, 2020 / 
Notices  

[[Page 19580]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XR074]


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

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

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

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

DATES: Comments and information must be received no later than May 7, 
2020.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Physical comments should be sent to 
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments 
should be sent to [email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments received electronically, including 
all attachments, must not exceed a 25-megabyte file size. Attachments 
to electronic comments will be accepted in Microsoft Word or Excel or 
Adobe PDF file formats only. All comments received are a part of the 
public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.

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

SUPPLEMENTARY INFORMATION: 

Background

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

National Environmental Policy Act

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

Summary of Request

    On November 8, 2019, NMFS received a request from L-DEO for an IHA 
to take marine mammals incidental to a marine geophysical survey of the 
Cascadia Subduction Zone off the coasts of Washington, Oregon, and 
British Columbia, Canada. The application was deemed adequate and 
complete on March 6, 2020. L-DEO's request is for take of small numbers 
of 31 species of marine mammals by Level A and Level B harassment. 
Neither L-DEO nor NMFS expects serious injury or mortality to result 
from this activity and, therefore, an IHA is appropriate.
    NMFS has previously issued IHAs to L-DEO for similar surveys in the 
northeast Pacific (e.g., 84 FR 35073, July 22, 2019; 77 FR 41755, July 
16, 2012). 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 L-DEO, Woods Hole Oceanographic Institution 
(WHOI), and the University of Texas at Austin Institute of Geophysics 
(UTIG), with funding from the NSF, and in collaboration with 
researchers from Dalhousie University and Simon Fraser University (SFU) 
propose to conduct a high-energy seismic survey from the Research 
Vessel (R/V) Marcus G Langseth (Langseth) in the northeast Pacific 
Ocean beginning in June 2020. The seismic survey would be conducted at 
the Cascadia Subduction Zone off the coasts of Oregon, Washington, and

[[Page 19581]]

British Columbia, Canada. The proposed two-dimensional (2-D) seismic 
survey would occur within the Exclusive Economic Zones (EEZs) of Canada 
and the United States, including U.S. state waters and Canadian 
territorial waters. The survey would use a 36-airgun towed array with a 
total discharge volume of ~6,600 cubic inches (in\3\) as an acoustic 
source, acquiring return signals using both a towed streamer as well 
ocean bottom seismometers (OBSs) and ocean bottom nodes (OBNs).
    The proposed study would use 2-D seismic surveying and OBSs and 
OBNs to investigate the Cascadia Subduction Zone and provide data 
necessary to illuminate the depth, geometry, and physical properties of 
the seismogenic portion and updip extent of the megathrust zone between 
the subducting Juan de Fuca plate and the overlying accretionary wedge/
North American plate. These data would provide essential constraints 
for earthquake and tsunami hazard assessment in this heavily populated 
region of the Pacific Northwest. The primary objectives of the survey 
proposed by researchers from L-DEO, WHOI, and UTIG is to characterize: 
(1) The deformation and topography of the incoming plate; (2) the 
depth, topography, and reflectivity of the megathrust; (3) sediment 
properties and amount of sediment subduction; and (4) the structure and 
evolution of the accretionary wedge, including geometry and 
reflectivity of fault networks, and how these properties vary along 
strike, spanning the full length of the margin and down dip across what 
may be the full width of the Cascadia Subduction Zone.

Dates and Duration

    The proposed survey is expected to last for 40 days, with 37 days 
of seismic operations, 2 days of equipment deployment, and 1 day of 
transit. R/V Langseth would likely leave out of and return to port in 
Astoria, Oregon, during June-July 2020.

Specific Geographic Region

    The proposed survey would occur within ~42-51[deg] N, ~124-130[deg] 
W. Representative survey tracklines are shown in Figure 1. Some 
deviation in actual track lines, including the order of survey 
operations, could be necessary for reasons such as science drivers, 
poor data quality, inclement weather, or mechanical issues with the 
research vessel and/or equipment. The survey is proposed to occur 
within the EEZs of the United States and Canada, as well as in U.S. 
state waters and Canadian territorial waters, ranging in depth 60-4400 
meters (m). A maximum of 6,890 km of transect lines would be surveyed. 
Most of the survey (63.2 percent) would occur in deep water (>1,000 m), 
26.4 percent would occur in intermediate water (100-1,000 m deep), and 
10.4 percent would take place in shallow water <100 m deep. 
Approximately 4 percent of the transect lines (295 km) would be 
undertaken in Canadian territorial waters (from 0-12 nautical miles 
(22.2 km) from shore), with most effort in intermediate waters. NMFS 
cannot authorize the incidental take of marine mammals in the 
territorial seas of foreign nations, as the MMPA does not apply in 
those waters. However, NMFS has still calculated the level of 
incidental take in the entire activity area (including Canadian 
territorial waters) as part of the analysis supporting our preliminary 
determination under the MMPA that the activity will have a negligible 
impact on the affected species.

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[GRAPHIC] [TIFF OMITTED] TN07AP20.000

Detailed Description of Specific Activity

    The procedures to be used for the proposed surveys would be similar 
to those used during previous seismic surveys by L-DEO and would use 
conventional seismic methodology. The surveys would involve one source 
vessel, R/V Langseth, which is owned by NSF and operated on its behalf 
by L-DEO. R/V Langseth would deploy an array of 36 airguns as an energy 
source with a total volume of ~6,600 in\3\. The array consists of 20 
Bolt 1500LL airguns with volumes of 180 to 360 in\3\ and 16 Bolt 
1900LLX airguns with volumes of 40 to 120 in\3\. The airgun array 
configuration is illustrated in Figure 2-11 of NSF and USGS's 
Programmatic Environmental Impact Statement (PEIS; NSF-USGS, 2011). The 
vessel speed during seismic operations would be approximately 4.2 knots 
(~7.8 km/hour) during the survey and the airgun array would be towed at 
a depth of 12 m. The receiving system would consist of one 15-kilometer 
(km) long hydrophone streamer, OBSs, and OBNs. R/V Oceanus, which is 
owned by NSF and operated by Oregon State University, would be used to 
deploy the OBSs and OBNs. As the airguns are towed along the survey 
lines, the hydrophone streamer would transfer the data to the on-board 
processing system, and the OBSs and OBNs would receive and store the 
returning acoustic signals internally for later analysis.
    Long 15-km-offset multichannel seismic (MCS) data would be acquired 
along numerous 2-D profiles oriented perpendicular to the margin and 
located

[[Page 19583]]

to provide coverage in areas inferred to be rupture patches during past 
earthquakes and their boundary zones. The survey would also include 
several strike lines including one continuous line along the 
continental shelf centered roughly over gravity-inferred fore-arc 
basins to investigate possible segmentation near the down-dip limit of 
the seismogenic zone. The margin normal lines would extend ~50 km 
seaward of the deformation front to image the region of subduction bend 
faulting in the incoming oceanic plate, and landward of the deformation 
front to as close to the shoreline as can be safely maneuvered. It is 
proposed that the southern transects off Oregon are acquired first, 
followed by the profiles off Washington and Vancouver Island, British 
Columbia.
    The OBSs would consist of short-period multi-component OBSs from 
the Ocean Bottom Seismometer Instrument Center (OBSIC) and a large-N 
array of OBNs from a commercial provider to record shots along ~11 MCS 
margin-perpendicular profiles. OBSs would be deployed at 10-km spacing 
along ~11 profiles from Vancouver Island to Oregon, and OBNs would be 
deployed at a 500-m spacing along a portion of two profiles off Oregon. 
Two OBS deployments would occur with a total of 115 instrumented 
locations. 60 OBSs would be deployed to instrument seven profiles off 
Oregon, followed by a second deployment of 55 OBSs to instrument four 
profiles off Washington and Vancouver Island. The first deployment off 
Oregon would occur prior to the start of the proposed survey, after 
which R/V Langseth would acquire data in the southern portion of the 
study area. R/V Oceanus would start recovering the OBSs from deployment 
1, and then re-deploy 55 OBSs off Washington and Vancouver Island, so 
that R/V Langseth can acquire data in the northern portion of the 
survey area. The OBSs have a height and diameter of ~1 m, and an ~80 
kilogram (kg) anchor. To retrieve OBSs, an acoustic release transponder 
(pinger) is used to interrogate the instrument at a frequency of 8-11 
kHz, and a response is received at a frequency of 11.5-13 kHz. The 
burn-wire release assembly is then activated, and the instrument is 
released to float to the surface from the anchor, which is not 
retrieved.
    A total of 350 OBNs would be deployed: 229 nodes along one transect 
off northern Oregon, and 121 nodes along a second transect off central 
Oregon. The nodes are not connected to each other; each node is 
independent from each other, and there are no cables attached to them. 
Each node has internal batteries; all data is recorded and stored 
internally. The nodes weigh 21 kg in air (9.5 kg in water). As the OBNs 
are small (330 millimeters (mm) x 289 mm x 115 mm), compact, not 
buoyant, and lack an anchor-release mechanism, they cannot be deployed 
by free-fall as with the OBSs. The nodes would be deployed and 
retrieved using a remotely operated vehicle (ROV); the ROV would be 
deployed from R/V Oceanus. OBNs would be deployed 17 days prior to the 
start of the R/V Langseth cruise. The ROV would be fitted with a skid 
with capacity for 32 units, lowered to the seafloor, and towed at a 
speed of 0.6 knots at 5-10 m above the seafloor between deployment 
sites. After the 32 units are deployed, the ROV would be retrieved, the 
skid would be reloaded with another 32 units, and sent back to the 
seafloor for deployment, and so on. The ROV would recover the nodes 3 
days after the completion of the R/V Langseth cruise. The nodes would 
be recovered one by one by a suction mechanism. Take of marine mammals 
is not expected to occur incidental to L-DEO's use of OBSs and OBNs.
    In addition to the operations of the airgun array, a multibeam 
echosounder (MBES), a sub-bottom profiler (SBP), and an Acoustic 
Doppler Current Profiler (ADCP) would be operated from R/V Langseth 
continuously during the seismic surveys, but not during transit to and 
from the survey area. All planned geophysical data acquisition 
activities would be conducted by L-DEO with on-board assistance by the 
scientists who have proposed the studies. The vessel would be self-
contained, and the crew would live aboard the vessel. Take of marine 
mammals is not expected to occur incidental to use of the MBES, SBP, or 
ADCP because they will be operated only during seismic acquisition, and 
it is assumed that, during simultaneous operations of the airgun array 
and the other sources, any marine mammals close enough to be affected 
by the MBES, SBP, and ADCP would already be affected by the airguns. 
However, whether or not the airguns are operating simultaneously with 
the other sources, given 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. Proposed 
mitigation, monitoring, and reporting measures are described in detail 
later in this document (please see Proposed Mitigation and Proposed 
Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS's 
website (https://www.fisheries.noaa.gov/find-species).
    Table 1 lists all species with expected potential for occurrence in 
the survey area and summarizes information related to the population or 
stock, including regulatory status under the MMPA and ESA and potential 
biological removal (PBR), where known. For taxonomy, we follow 
Committee on Taxonomy (2019). PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population (as described in NMFS's 
SARs). While no mortality is anticipated or authorized here, PBR and 
annual serious injury and mortality from anthropogenic sources are 
included here as gross indicators of the status of the species and 
other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS's stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS's U.S. Pacific and Alaska SARs (Caretta et al., 2019; Muto et al., 
2019). All MMPA stock information presented in Table 1 is the most 
recent available at the time of publication and is available in the 
2018 SARs (Caretta et al., 2019; Muto et al., 2019) and draft 2019 SARs 
(available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports). Where 
available, abundance and status information is also presented

[[Page 19584]]

for marine mammals in Canadian waters in British Columbia.

                                               Table 1--Marine Mammals That Could Occur in the Survey Area
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                                                                                            Stock abundance
                                                                         ESA/MMPA status;   (CV, Nmin, most
          Common name              Scientific name          Stock         strategic (Y/N)   recent abundance           PBR             Annual M/SI \3\
                                                                                \1\           survey) \2\
 
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family Eschrichtiidae:
    Gray whale.................  Eschrichtius        Eastern North       -/-; N            26,960 (0.05,      801.................  138.
                                  robustus.           Pacific.                              25,849, 2016).
Family Balaenopteridae
 (rorquals):
    Humpback whale.............  Megaptera           California/Oregon/  -/-; Y            2,900 (0.05,       16.7................  >42.1.
                                  novaeangliae.       Washington.                           2,784, 2014).
                                                     Central North       -/-; Y            10,103 (0.30,      83..................  25.
                                                      Pacific.                              7,891, 2006).
    Minke whale................  Balaenoptera        California/Oregon/  -/-; N            636 (0.72, 369,    3.5.................  >1.3.
                                  acutorostrata.      Washington.                           2014).
    Sei whale..................  Balaenoptera        Eastern North       E/D; Y            519 (0.4, 374,     0.75................  >0.2.
                                  borealis.           Pacific.                              2014).
    Fin whale..................  Balaenoptera        California/Oregon/  E/D; Y            9,029 (0.12,       81..................  >2.0.
                                  physalus.           Washington.                           8,127, 2014).
                                                     Northeast Pacific.  E/D; Y            3,168 (0.26,       5.1.................  0.4.
                                                                                            2,554, 2013).
    Blue whale.................  Balaenoptera        Eastern North       E/D; Y            1,496 (0.44,       1.2.................  >19.4.
                                  musculus.           Pacific.                              1,050, 2014).
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                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family Physeteridae:
    Sperm whale................  Physeter            California/Oregon/  E/D; Y            1,997 (0.57,       2.5.................  0.4.
                                  macrocephalus.      Washington.                           1,270, 2014).
Family Kogiidae:
    Pygmy sperm whale..........  Kogia breviceps...  California/Oregon/  -/-; N            4,111 (1.12,       19..................  0.
                                                      Washington.                           1,924, 2014).
    Dwarf sperm whale..........  Kogia sima........  California/Oregon/  -/-; N            Unknown (Unknown,  Undetermined........  0.
                                                      Washington.                           Unknown, 2014).
Family Ziphiidae (beaked
 whales):
    Cuvier's beaked whale......  Ziphius             California/Oregon/  -/-; N            3,274 (0.67,       21..................  <0.1.
                                  cavirostris.        Washington.                           2,059, 2014).
    Baird's beaked whale.......  Berardius bairdii.  California/Oregon/  -/-; N            2,697 (0.6,        16..................  0
                                                      Washington.                           1,633, 2014).
    Blainville's beaked whale..  Mesoplodon          California/Oregon/  -/-; N            3,044 (0.54,       20..................  0.1.
                                  densirostris.       Washington.                           1,967, 2014).
    Hubbs' beaked whale........  Mesoplodon
                                  carlshubbi.
    Stejneger's beaked whale...  Mesoplodon
                                  stejnegeri.
Family Delphinidae:
    Bottlenose dolphin.........  Tursiops truncatus  California/Oregon/  -/-; N            1,924 (0.54,       11..................  >1.6.
                                                      Washington                            1,255, 2014).
                                                      offshore.
    Striped dolphin............  Stenella            California/Oregon/  -/-; N            29,211 (0.2,       238.................  >0.8.
                                  coeruleoalba.       Washington.                           24,782, 2014).
    Common dolphin.............  Delphinus delphis.  California/Oregon/  -/-; N            969,861 (0.17,     8,393...............  >40.
                                                      Washington.                           839,325, 2014).
    Pacific white-sided dolphin  Lagenorhynchus      California/Oregon/  -/-; N            26,814 (0.28,      191.................  7.5.
                                  obliquidens.        Washington.                           21,195, 2014).
                                                     British Columbia    N/A               22,160 (unknown,   Unknown.............  Unknown.
                                                      \4\.                                  16,522, 2008).
    Northern right whale         Lissodelphis        California/Oregon/  -/-; N            26,556 (0.44,      179.................  3.8.
     dolphin.                     borealis.           Washington.                           18,608, 2014).
    Risso's dolphin............  Grampus griseus...  California/Oregon/  -/-; N            6,336 (0.32,       46..................  >3.7.
                                                      Washington.                           4,817, 2014).
    False killer whale.........  Pseudorca           N/A...............  N/A               N/A..............  N/A.................  N/A.
                                  crassidens.
    Killer whale...............  Orcinus orca......  Offshore..........  -/-; N            300 (0.1, 276,     2.8.................  0.
                                                                                            2012).
                                                     Southern Resident.  E/D; Y            75 (N/A, 75,       0.13................  0.
                                                                                            2018).
                                                     Northern Resident.  -/-; N            302 (N/A, 302,     2.2.................  0.2.
                                                                                            2018).
                                                     West Coast          -/-; N            243 (N/A, 243,     2.4.................  0.
                                                      Transient.                            2009).
    Short-finned pilot whale...  Globicephala        California/Oregon/  -/-; N            836 (0.79, 466,    4.5.................  1.2.
                                  macrorhynchus.      Washington.                           2014).
Family Phocoenidae (porpoises):
    Harbor porpoise............  Phocoena phocoena.  Northern Oregon/    -/-; N            21,487 (0.44,      151.................  >3.0.
                                                      Washington Coast.                     15,123, 2011).
                                                     Northern            -/-; N            35,769 (0.52,      475.................  >0.6.
                                                      California/                           23,749, 2011).
                                                      Southern Oregon.
                                                     British Columbia    N/A               8,091 (unknown,    Unknown.............  Unknown.
                                                      \4\.                                  4,885, 2008).
    Dall's porpoise............  Phocoenoides dalli  California/Oregon/  -/-; N            25,750 (0.45,      172.................  0.3.
                                                      Washington.                           17,954, 2014).
                                                     British Columbia    N/A               5,303 (unknown,    Unknown.............  Unknown.
                                                      \4\.                                  4,638, 2008).
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 19585]]

 
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals
 and sea lions):.
    Northern fur seal..........  Callorhinus         Eastern Pacific...  -/D; Y            620,660 (0.2,      11,295..............  399.
                                  ursinus.                                                  525,333, 2016).
                                                     California........  -/D; N            14,050 (N/A,       451.................  1.8.
                                                                                            7,524, 2013).
    California sea lion........  Zalophus            U.S...............  -/-; N            257,606 (N/A,      14,011..............  >321.
                                  californianus.                                            233,515, 2014).
    Steller sea lion...........  Eumetopias jubatus  Eastern U.S.......  -/-; N            43,201 (see SAR,   2,592...............  113.
                                                                                            43,201, 2017).
                                                     British Columbia    N/A               4,037 (unknown,    Unknown.............  Unknown.
                                                      \4\.                                  1,100, 2008).
    Guadalupe fur seal.........  Arctocephalus       Mexico to           T/D; Y            34,187 (N/A,       1,062...............  >3.8.
                                  philippii           California.                           31,019, 2013).
                                  townsendi.
Family Phocidae (earless
 seals):
    Harbor seal................  Phoca vitulina....  Oregon/Washington   -/-; N            Unknown (Unknown,  Undetermined........  10.6.
                                                      Coastal.                              Unknown, 1999).
                                                     British Columbia    N/A               24,916 (Unknown,   Unknown.............  Unknown.
                                                      \4\.                                  19,666, 2008).
    Northern elephant seal.....  Mirounga            California          -/-; N            179,000 (N/A,      4,882...............  8.8.
                                  angustirostris.     Breeding.                             81,368, 2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments assessments. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\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.
\4\ Best et al. (2015) total abundance estimates for animals in British Columbia based on surveys of the Strait of Georgia, Johnstone Strait, Queen
  Charlotte Sound, Hecate Strait, and Dixon Entrance.

    All species that could potentially occur in the proposed survey 
areas are included in Table 1. However, additional species have been 
recorded in the specified geographic region but are considered 
sufficiently rare that take is not anticipated. The temporal and/or 
spatial occurrence of North Pacific right whales (Eubalaena japonica) 
is such that take is not expected to occur, and they are not discussed 
further beyond the explanation provided here. Only 82 sightings of 
right whales in the entire eastern North Pacific were reported from 
1962 to 1999, with the majority of these occurring in the Bering Sea 
and adjacent areas of the Aleutian Islands (Brownell et al., 2001). 
Most sightings in the past 20 years have occurred in the southeastern 
Bering Sea, with a few in the Gulf of Alaska (Wade et al., 2011). 
Despite many miles of systematic aerial and ship-based surveys for 
marine mammals off the coasts of Washington, Oregon and California over 
several years, only seven documented sightings of right whales were 
made from 1990 to 2000 (Waite et al., 2003), and NMFS is not aware of 
any documented sightings in the area since then. 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.
    In addition, the Northern sea otter (Enhydra lutris kenyoni) may be 
found in coastal waters of the survey area. However, sea otters are 
managed by the U.S. Fish and Wildlife Service and are not considered 
further in this document.

Gray Whale

    Two separate populations for gray whales have been recognized in 
the North Pacific: The eastern North Pacific and the western North 
Pacific (or Korean-Okhotsk) 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). Thus it is possible that whales 
from either the ESA listed endangered Western North Pacific distinct 
population segment (DPS) or the delisted Eastern North Pacific DPS 
could occur in the survey area, although it is unlikely that a gray 
whale from the Western North Pacific DPS would be encountered during 
the time of the survey as they are expected to be in their feeding 
grounds in the western North Pacific at the time of the proposed 
survey. NMFS expects that any gray whales encountered by L-DEO during 
the proposed survey would be from the Eastern North Pacific DPS only, 
and is not proposing to authorize take of the endangered Western North 
Pacific DPS; therefore, the Western North Pacific DPS will not be 
discussed further in this document.
    The eastern North Pacific gray whale breeds and winters in Baja 
California, and migrates north to summer feeding grounds in the 
northern Bering Sea, Chukchi Sea, and western Beaufort Sea (Rice and 
Wolman 1971; Rice 1998; Jefferson et al., 2015). The northward 
migration occurs from late February to June (Rice and Wolman 1971), 
with a peak in the Gulf of Alaska during mid-April (Braham 1984). 
Instead of migrating to arctic and sub-arctic waters, some individuals 
spend the summer months scattered along the coast from California to 
southeast Alaska (Rice and Wolman 1971; Nerini 1984; Darling et al., 
1998; Calambokidis and Quan 1999; Dunham and Duffus 2001, 2002; 
Calambokidis et al., 2002, 2015, 2017). There is genetic evidence 
indicating the existence of this Pacific Coast Feeding Group (PCFG) is 
a

[[Page 19586]]

distinct local subpopulation (Frasier et al., 2011; Lang et al., 2014) 
and the United States and Canada recognize it as such (COSEWIC 2017; 
Caretta et al., 2019a). However, the status of the PCFG as a separate 
stock is currently unresolved (Weller et al., 2013). For the purposes 
of abundance estimates, the PCFG is defined as occurring between 
41[deg] N to 52[deg] N from June 1 to November 30 (IWC 2012). The 2015 
abundance estimate for the PCFG was 243 whales (Calambokidis et al., 
2017); approximately 100 of those may occur in British Columbia during 
summer (Ford 2014). In British Columbia, most summer resident gray 
whales are found in Clayoquot Sound, Barkley Sound, and along the 
southwestern shore of Vancouver Island, and near Cape Caution on 
mainland British Columbia (Ford 2014). During surveys in British 
Columbia waters during summer, most sightings of gray whales were made 
within 10 km of shore and in water shallower than 100 m (Ford et al., 
2010a). Two sightings of three gray whales were seen from R/V Northern 
Light during a survey off southern Washington in July 2012 (RPS 2012a).
    Biologically Important Areas (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 in Washington, Depoe Bay and Cape Blanco and Orford Reef in 
Oregon, and Point St. George in California; most of these areas are of 
importance from late spring through early fall (Calambokidis et al., 
2015). 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 surveys 
would occur during the late spring/summer feeding season, when most 
individuals from the eastern North Pacific stock occur farther north. 
Nonetheless, individual gray whales, particularly those from the PCFG 
could be encountered in nearshore waters of the proposed project area.
    On May 30, 2019, NMFS declared an unusual mortality event (UME) for 
gray whales after elevated numbers of strandings occurred along the 
U.S. west coast. As of February 8, 2020, a total of 236 stranded gray 
whales have been reported, including 124 in the United States (48 in 
Alaska, 35 in Washington, 6 in Oregon, and 35 in California), 101 in 
Mexico, and 11 in Canada. Full or partial necropsy examinations were 
conducted on a subset of the whales. Preliminary findings in several of 
the whales have shown evidence of emaciation. These findings are not 
consistent across all of the whales examined, so more research is 
needed. The UME is ongoing, and NMFS continues to investigate the 
cause(s). Additional information about the UME is available at https://www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast.

Humpback Whale

    The humpback whale is found throughout all of the oceans of the 
world (Clapham 2009). The worldwide population of humpbacks is divided 
into northern and southern ocean populations, but genetic analyses 
suggest some gene flow (either past or present) between the North and 
South Pacific (e.g., Baker et al. 1993; Caballero et al. 2001). 
Geographical overlap of these populations has been documented only off 
Central America (Acevedo and Smultea 1995; Rasmussen et al. 2004, 
2007). Although considered to be mainly a coastal species, humpback 
whales often traverse deep pelagic areas while migrating (Clapham and 
Mattila 1990; Norris et al. 1999; Calambokidis et al. 2001).
    Humpback whales migrate between summer feeding grounds in high 
latitudes and winter calving and breeding grounds in tropical waters 
(Clapham and Mead 1999). North Pacific humpback whales summer in 
feeding grounds along the Pacific Rim and in the Bering and Okhotsk 
seas (Pike and MacAskie 1969; Rice 1978; Winn and Reichley 1985; 
Calambokidis et al. 2000, 2001, 2008). Humpback 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, 2016) pursuant to the ESA. The DPSs that occur in U.S. waters do not 
necessarily equate to the existing stocks designated under the MMPA and 
shown in Table 1. Because MMPA stocks cannot be portioned, i.e., parts 
managed as ESA-listed while other parts managed as not 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).
    Within the proposed survey area, three current DPSs may occur: The 
Hawaii DPS (not listed), Mexico DPS (threatened), and Central America 
DPS (endangered). According to Wade et al. (2017), the probability that 
whales encountered in Oregon and California waters are from a given DPS 
are as follows: Mexico DPS, 32.7 percent; Central America DPS, 67.2 
percent; Hawaii DPS, 0 percent. The probability that humpback whales 
encountered in Washington and British Columbia waters are as follows: 
Mexico DPS, 27.9 percent; Central America DPS, 8.7 percent; Hawaii DPS, 
63.5 percent.
    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). The highest 
numbers have been reported off Oregon during May and June and off 
Washington during July-September. Humpbacks occur primarily over the 
continental shelf and slope during the summer, with few reported in 
offshore pelagic waters (Green et al., 1992; Calambokidis et al., 2004, 
2015; Becker et al., 2012; Barlow 2016). Six humpback whale sightings 
(8 animals) were made off Washington/Oregon during the June-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 southern Washington (RPS 2012a), and 11 sightings (23 animals) 
during the July 2012 L-DEO seismic survey off Oregon (RPS 2012c).
    Humpback whales are common in the waters of British Columbia, where 
they occur in inshore, outer coastal, and continental shelf waters, as 
well as offshore (Ford 2014). Williams and Thomas (2007) estimated an 
abundance of 1,310 humpback whales in inshore coastal waters of British 
Columbia based on surveys conducted in 2004 and 2005. Best et al. 
(2015) provided an estimate of 1,029 humpbacks in British Columbia 
based on surveys during 2004-2008. In British Columbia, humpbacks are 
typically seen within 20 km from the coast, in water less than 500 m 
deep (Ford et al., 2010a). The greatest numbers of humpbacks are seen 
in British Columbia between April and November, although humpbacks are 
known to occur there throughout the

[[Page 19587]]

year (Ford et al., 2010a; Ford 2014). Humpback whales in British 
Columbia are thought to belong to at least two distinct feeding stocks; 
those identified off southern British Columbia show little interchange 
with those seen off northern British Columbia (Calambokidis et al., 
2001, 2008). Humpback whales identified in southern British Columbia 
show a low level of interchange with those seen off California/Oregon/
Washington (Calambokidis et al., 2001).
    BIAs for feeding humpbacks along the coasts of Oregon and 
Washington, which have been described from May to November, are all 
within approximately 80 km from shore, and include the waters off 
northern Washington, and Stonewall and Heceta Bank, Oregon 
(Calambokidis et al., 2015). On October 9, 2019, NMFS issued a proposed 
rule to designate critical habitat in nearshore waters of the North 
Pacific Ocean for the endangered Central America DPS and the threatened 
Mexico DPS of humpback whale (NMFS 2019b). Critical habitat for the 
Central America DPS and Mexico DPS was proposed within the California 
Current Ecosystem (CCE) off the coasts California, Oregon, and 
Washington, representing areas of key foraging habitat. Off Washington 
and northern Oregon, the critical habitat would extend from the 50-m 
isobath out to the 1200-m isobath; off southern Oregon (south of 
42[deg]10' N), it would extend out to the 2000-m isobath (NMFS 2019b).
    Critical habitat for humpbacks has been designated in four 
locations in British Columbia (DFO 2013), including in the waters of 
the proposed survey area off southwestern Vancouver Island. The other 
three locations are located north of the proposed survey area at Haida 
Gwaii (Langara Island and Southeast Moresby Island) and at Gil Island 
(DFO 2013). These areas show persistent aggregations of humpback whales 
and have features such as prey availability, suitable acoustic 
environment, water quality, and physical space that allow for feeding, 
foraging, socializing, and resting (DFO 2013). Two of the proposed 
transect lines intersect the critical habitat on Swiftsure and La 
P[eacute]rouse Banks.

Minke Whale

    The minke whale has a cosmopolitan distribution that spans from 
tropical to polar regions in both hemispheres (Jefferson et al. 2015). 
In the Northern Hemisphere, the minke whale is usually seen in coastal 
areas, but can also be seen in pelagic waters during its northward 
migration in spring and summer and southward migration in autumn 
(Stewart and Leatherwood 1985). In the North Pacific, the summer range 
of the minke whale extends to the Chukchi Sea; in the winter, the 
whales move farther south to within 2[deg] of the Equator (Perrin and 
Brownell 2009).
    The International Whaling Commission (IWC) recognizes three stocks 
of minke whales in the North Pacific: The Sea of Japan/East China Sea, 
the rest of the western Pacific west of 180[deg] N, and the remainder 
of the Pacific (Donovan 1991). Minke whales are relatively common in 
the Bering and Chukchi seas and in the Gulf of Alaska, but are not 
considered abundant in any other part of the eastern Pacific 
(Brueggeman et al. 1990). In the far north, minke whales are thought to 
be migratory, but they are believed to be year-round residents in 
coastal waters off the west coast of the United States (Dorsey et al. 
1990).
    Sightings of minke whales have been reported off Oregon and 
Washington in shelf and deeper waters (Green et al., 1992; Adams et 
al., 2014; Barlow 2016; Caretta et al., 2019a). There were no sightings 
of minke whales off Washington/Oregon during the June-July 2012 L-DEO 
Juan de Fuca plate seismic survey or during the July 2012 L-DEO seismic 
survey off Oregon (RPS 2012b,c). One minke whale was seen during the 
July 2012 L-DEO seismic survey off southern Washington (RPS 2012a). 
Minke whales are sighted regularly in nearshore waters of British 
Columbia, but they are not considered abundant (COSEWIC 2006). They are 
most frequently sighted around the Gulf Islands and off northeastern 
Vancouver Island (Ford 2014). They are also regularly seen off the east 
coast of Moresby Island, and in Dixon Entrance, Hecate Strait, Queen 
Charlotte Sound, and the west coast of Vancouver Island were they occur 
in shallow and deeper water (Ford et al., 2010a; Ford 2014). Williams 
and Thomas (2007) estimated minke whale abundance for inshore coastal 
waters of British Columbia at 388 individuals based on surveys 
conducted in 2004 and 2005 while Best et al. (2015) provided an 
estimate of 522 minke whales based on surveys during 2004-2008.

Sei Whale

    The distribution of the sei whale is not well known, but it is 
found in all oceans and appears to prefer mid-latitude temperate waters 
(Jefferson et al. 2015). The sei whale is pelagic and generally not 
found in coastal waters (Jefferson et al. 2015). It is found in deeper 
waters characteristic of the continental shelf edge region (Hain et al. 
1985) and in other regions of steep bathymetric relief such as 
seamounts and canyons (Kenney and Winn 1987; Gregr and Trites 2001). On 
feeding grounds, sei whales associate with oceanic frontal systems 
(Horwood 1987) such as the cold eastern currents in the North Pacific 
(Perry et al. 1999a). Sei whales migrate from temperate zones occupied 
in winter to higher latitudes in the summer, where most feeding takes 
place (Gambell 1985a). During summer in the North Pacific, the sei 
whale can be found from the Bering Sea to the Gulf of Alaska and down 
to southern 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 California, Oregon, and 
Washington (Brueggeman et al., 1990; Green et al., 1992; Barlow 1994, 
1997). Less than 20 confirmed sightings were reported in that region 
during extensive surveys between 1991 and 2014 (Green et al., 1992, 
1993; Hill and Barlow 1992; Caretta and Forney 1993; Mangels and 
Gerrodette 1994; Von Saunder and Barlow 1999; Barlow 2003, 2010, 2014; 
Forney 2007; Carretta et al., 2019a). 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 July 2012 L-DEO seismic surveys off Oregon and Washington 
(RPS 2012a,c).
    The patterns of seasonal abundance found in whaling records 
suggested that the whales were caught as they migrated to summer 
feeding grounds, with the peak of the migration in July and offshore 
movement in summer, from ~25 km to ~100 km from shore (Gregr et al., 
2000). Historical whaling data show that sei whales used to be 
distributed along the continental slope of British Columbia and over a 
large area off the northwest coast of Vancouver Island (Gregr and 
Trites 2001). Sei whales are now considered rare in Pacific waters of 
the United States and Canada; in British Columbia there were no 
sightings in the late 1900s after whaling ceased (Gregr et al., 2006). 
Ford (2014) only reported two sightings for British Columbia, both of 
those far offshore from Haida Gwaii. Possible sei whale vocalizations 
were detected off the west coast of Vancouver Island during spring and 
summer 2006 and 2007 (Ford et al., 2010b). Gregr and Trites (2001) 
proposed that the area off northwestern Vancouver Island and the 
continental slope may be critical habitat for sei whales because of 
favorable feeding conditions.

[[Page 19588]]

Fin Whale

    The fin whale is widely distributed in all the world's oceans 
(Gambell 1985b), but typically occurs in temperate and polar regions 
from 20-70[deg] north and south of the Equator (Perry et al. 1999b). 
Northern and southern fin whale populations are distinct and are 
recognized as different subspecies (Aguilar 2009). Fin whales occur in 
coastal, shelf, and oceanic waters. Sergeant (1977) suggested that fin 
whales tend to follow steep slope contours, either because they detect 
them readily or because biological productivity is high along steep 
contours because of tidal mixing and perhaps current mixing. Stafford 
et al. (2009) noted that sea-surface temperature is a good predictor 
variable for fin whale call detections in the North Pacific.
    Fin whales appear to have complex seasonal movements and are 
seasonal migrants; they mate and calve in temperate waters during the 
winter and migrate to feed at northern latitudes during the summer 
(Gambell 1985b). The North Pacific population summers from the Chukchi 
Sea to California and winters from California southwards (Gambell 
1985b). Aggregations of fin whales are found year-round off southern 
and central California (Dohl et al. 1980, 1983; Forney et al. 1995; 
Barlow 1997) and in the summer off Oregon (Green et al. 1992; Edwards 
et al. 2015). Vocalizations from fin whales have also been detected 
year-round off northern California, Oregon, and Washington (Moore et 
al. 1998, 2006; Watkins et al. 2000a,b; Stafford et al. 2007, 2009; 
Edwards et al. 2015).
    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 2,369-3,940 m deep (RPS 2012b). 
Fourteen fin whale sightings (28 animals) were made during the July 
2012 L-DEO seismic surveys off southern Washington (RPS 2012a). No fin 
whales were sighted during the July 2012 L-DEO seismic survey off 
Oregon (RPS 2012c). Fin whales were also seen off southern Oregon 
during July 2012 in water >2000 m deep during surveys by Adams et al. 
(2014).
    Whaling records indicate fin whale occurrence off the west coast of 
British Columbia increased gradually from March to a peak in July, then 
decreased rapidly in September and October (Gregr et al., 2000). Fin 
whales occur throughout British Columbia waters near and past the 
continental shelf break, as well as in inshore waters (Ford 2014). Fin 
whales were the second most common cetacean sighted during DFO surveys 
in 2002-2008 (Ford et al., 2010a). They appear to be more common in 
northern British Columbia, but sightings have been made along the shelf 
edge and in deep waters off western Vancouver Island (Ford et al., 
1994, 2010a; Calambokidis et al., 2003; Ford 2014). Acoustic detections 
have been made throughout the year in pelagic waters west of Vancouver 
Island (Edwards et al., 2015). Gregr and Trites (2001) proposed that 
the area off northwestern Vancouver Island and the continental slope 
may be critical habitat for fin whales because of favorable feeding 
conditions.

Blue Whale

    The blue whale has a cosmopolitan distribution and tends to be 
pelagic, only coming nearshore to feed and possibly to breed (Jefferson 
et al. 2015). Although it has been suggested that there are at least 
five subpopulations of blue whales in the North Pacific (NMFS 1998), 
analysis of blue whale calls monitored from the U.S. Navy Sound 
Surveillance System (SOSUS) and other offshore hydrophones (see 
Stafford et al., 1999, 2001, 2007; Watkins et al., 2000a; Stafford 
2003) suggests that there are two separate populations: One in the 
eastern and one in the western North Pacific (Sears and Perrin 2009). 
Broad-scale acoustic monitoring indicates that blue whales occurring in 
the northeast Pacific during summer and fall may winter in the eastern 
tropical Pacific (Stafford et al., 1999, 2001).
    The distribution of the species, at least during times of the year 
when feeding is a major activity, occurs in areas that provide large 
seasonal concentrations of euphausiids (Yochem and Leatherwood 1985). 
The eastern North Pacific stock feeds in California waters from June-
November (Calambokidis et al., 1990; Mate et al., 1999). There are nine 
BIAs for feeding blue whales off the coast of California (Calambokidis 
et al., 2015), and core areas have also been identified there (Irvine 
et al., 2014).
    Blue whales are considered rare off Oregon, Washington, and British 
Columbia (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). 
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).
    Sightings of blue whales in offshore waters of British Columbia are 
rare (Ford 2014; DFO 2017) and there is no abundance estimate for 
British Columbia waters (Nichol and Ford 2012). During surveys of 
British Columbia from 2002-2013, 16 sightings of blue whales were made, 
all of which occurred just to the south or west of Haida Gwaii during 
June, July, and August (Ford 2014). There have also been sightings off 
Vancouver Island during summer and fall (Calambokidis et al., 2004b; 
Ford 2014), with the most recent one reported off southwestern Haida 
Gwaii in July 2019 (CBC 2019).

Sperm Whale

    The sperm whale is the largest of the toothed whales, with an 
extensive worldwide distribution (Rice 1989). Sperm whale distribution 
is linked to social structure: Mixed groups of adult females and 
juvenile animals of both sexes generally occur in tropical and 
subtropical waters, whereas adult males are commonly found alone or in 
same-sex aggregations, often occurring in higher latitudes outside the 
breeding season (Best 1979; Watkins and Moore 1982; Arnbom and 
Whitehead 1989; Whitehead and Waters 1990). Males can migrate north in 
the summer to feed in the Gulf of Alaska, Bering Sea, and waters around 
the Aleutian Islands (Kasuya and Miyashita 1988). Mature male sperm 
whales migrate to warmer waters to breed when they are in their late 
twenties (Best 1979).
    Sperm whales generally are distributed over large areas that have 
high secondary productivity and steep underwater topography, in waters 
at least 1000 m deep (Jaquet and Whitehead 1996; Whitehead 2009). They 
are often found far from shore, but can be found closer to oceanic 
islands that rise steeply from deep ocean waters (Whitehead 2009). 
Adult males can occur in water depths <100 m and as shallow as 40 m 
(Whitehead et al., 1992; Scott and Sadove 1997). They can dive as deep 
as ~2 km and possibly deeper on rare occasions for periods of over 1 h; 
however, most of their foraging occurs at depths of ~300-800 m for 30-
45 min (Whitehead 2003).
    Sperm whales are distributed widely across the North Pacific (Rice 
1989). Off California, they occur year-round (Dohl et al., 1983; Barlow 
1995; Forney et al., 1995), with peak abundance from April to mid-June 
and from August to mid-November (Rice 1974). Off Oregon, sperm whales 
are seen in every season except winter (Green et al., 1992). Sperm 
whales were sighted during

[[Page 19589]]

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 SWFSC vessel survey (Barlow 2016). A 
single sperm whale was sighted during a 2009 survey to the west of the 
proposed survey area (Holst 2017).
    Oleson et al. (2009) noted a significant diel pattern in the 
occurrence of sperm whale clicks at offshore and inshore monitoring 
locations off Washington, whereby clicks were more commonly heard 
during the day at the offshore site and were more common at night at 
the inshore location, suggesting possible diel movements up and down 
the slope in search of prey. Sperm whale acoustic detections were also 
reported at the inshore site from June through January 2009, with an 
absence of calls during February to May ([Scirc]irovi[cacute] et al., 
2012). In addition, sperm whales were sighted during surveys off 
Washington in June 2011 and off Oregon in October 2011 (Adams et al. 
2014).
    Whaling records report large numbers of sperm whales taken in 
April, with a peak in May. Analysis of data on catch locations, sex of 
the catch, and fetus lengths indicated that males and females were both 
50-80 km from shore while mating in April and May, and that by July and 
August, adult females had moved to waters >100 km offshore to calve), 
and adult males had moved to within ~25 km of shore (Gregr et al., 
2000). At least in the whaling era, females did not travel north of 
Vancouver Island whereas males were observed in deep water off Haida 
Gwaii (Gregr et al., 2000). After the whaling era, sperm whales have 
been sighted and detected acoustically in British Columbia waters 
throughout the year, with a peak during summer (Ford 2014). Acoustic 
detections at La P[eacute]rouse Bank off southwestern Vancouver Island 
have been recorded during spring and summer (Ford et al., 2010b). 
Sightings west of Vancouver Island and Haida Gwaii indicate that this 
species still occurs in British Columbia in small numbers (Ford et al., 
1994; Ford 2014). Based on whaling data, Gregr and Trites (2001) 
proposed that the area off northwestern Vancouver Island and the 
continental slope may be critical habitat for male sperm whales because 
of favorable feeding conditions.

Pygmy and Dwarf Sperm Whales

    The pygmy and dwarf sperm whales are distributed widely throughout 
tropical and temperate seas, but their precise distributions are 
unknown as most information on these species comes from strandings 
(McAlpine 2009). They are difficult to sight at sea, perhaps because of 
their avoidance reactions to ships and behavior changes in relation to 
survey aircraft (W[uuml]rsig et al. 1998). The two species are 
difficult to distinguish from one another when sighted (McAlpine 2009).
    Both Kogia species are sighted primarily along the continental 
shelf edge and slope and over deeper waters off the shelf (Hansen et 
al. 1994; Davis et al. 1998). Several studies have suggested that pygmy 
sperm whales live mostly beyond the continental shelf edge, whereas 
dwarf sperm whales tend to occur closer to shore, often over the 
continental shelf (Rice 1998; Wang et al. 2002; MacLeod et al. 2004). 
Barros et al. (1998), on the other hand, suggested that dwarf sperm 
whales could be more pelagic and dive deeper than pygmy sperm whales. 
It has also been suggested that the pygmy sperm whale is more temperate 
and the dwarf sperm whale more tropical, based at least partially on 
live sightings at sea from a large database from the eastern tropical 
Pacific (Wade and Gerrodette 1993). This idea is also supported by the 
distribution of strandings in South American waters (Mu[ntilde]oz-
Hincapi[eacute] et al. 1998).
    Pygmy and dwarf sperm whales are rarely sighted off Oregon and 
Washington, with only one sighting of an unidentified Kogia spp. beyond 
the U.S. EEZ, during the 1991-2014 NOAA vessel surveys (Carretta et 
al., 2019a). 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. There are several unconfirmed 
sighting reports of the pygmy sperm whale from the Canadian west coast 
(Baird et al., 1996). There is a stranding record of a pygmy sperm 
whale for northeastern Vancouver Island (Ford 2014), and there is a 
single dwarf sperm whale stranding record for southwestern Vancouver 
Island in September 1981 (Ford 2014). Willis and Baird (1998) state 
that the dwarf sperm whale is likely found in British Columbia waters 
more frequently than recognized, but Ford (2014) suggested that the 
presence of Kogia spp. in British Columbia waters is extralimital.

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).

Baird's Beaked Whale

    Baird's beaked whale has a fairly extensive range across the North 
Pacific, with concentrations occurring in the Sea of Okhotsk and Bering 
Sea (Rice 1998; Kasuya 2009). In the eastern Pacific, Baird's beaked 
whale is reported to occur as far south as San Clemente Island, 
California (Rice 1998; Kasuya 2009). Two forms of Baird's beaked whales 
have been recognized, the common slate-gray form and a smaller, rare 
black form (Morin et al., 2017). The gray form is seen off Japan, in 
the Aleutians, and on the west coast of North America, whereas the 
black form has been reported for northern Japan and the Aleutians 
(Morin et al., 2017). Recent genetic studies suggest that the black 
form could be a separate species (Morin et al., 2017). Baird's beaked 
whales are 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 are occasionally seen close to shore, but 
their primary habitat is in waters 1,000-3,000 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; Caretta et al., 2019a) from late spring to early fall (Green 
et al., 1992). In the eastern North Pacific, Baird's beaked whales 
apparently spend the winter and

[[Page 19590]]

spring far offshore, and in June move onto the continental slop, 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.
    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 near the planned survey area in August 2016 
during a SWFSC study using drifting acoustic recorders (Keating et al. 
2018).
    There are whaler's reports of Baird's beaked whales off the west 
coast of Vancouver Island throughout the whaling season (May-
September), especially in July and August (Reeves and Mitchell 1993). 
Twenty-four sightings have been made in British Columbia since the 
whaling era, including off the west coast of Vancouver Island (Ford 
2014). Three strandings have also been reported, including one on 
northeastern Haida Gwaii and two on the west coast of Vancouver Island.

Blainville's Beaked Whale

    Blainville's beaked whale is found in tropical and warm temperate 
waters of all oceans (Pitman 2009). It has the widest distribution 
throughout the world of all mesoplodont species and appears to be 
relatively common (Pitman 2009). Like other beaked whales, Blainville's 
beaked whale is generally found in waters 200-1400 m deep (Gannier 
2000; Jefferson et al. 2015). Blainville's beaked whale 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 
detection of Blainville's beaked whales recorded in Quinault Canyon off 
Washington in waters 1,400 m deep during 2011 (Baumann-Pickering et 
al., 2014).

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 U.S. West Coast (MacLeod et al. 2006). Most of 
the records are from California, but it has been sighted as far north 
as Prince Rupert, British Columbia (Mead 1989). Two strandings are 
known from Washington/Oregon (Norman et al. 2004). There have been no 
confirmed live sightings of Hubb's beaked whales in British Columbia.

Stejneger's Beaked Whale

    Stejneger's beaked whale occurs in subarctic and cool temperate 
waters of the North Pacific Ocean (Mead 1989). In the eastern North 
Pacific Ocean, it is distributed from Alaska to southern California 
(Mead et al. 1982; Mead 1989). Most stranding records are from Alaskan 
waters, and the Aleutian Islands appear to be its center of 
distribution (MacLeod et al. 2006). After Cuvier's beaked whale, 
Stejneger's beaked whale was the second most commonly stranded beaked 
whale species in Oregon and Washington (Norman et al. 2004). 
Stejneger's beaked whale calls were detected during acoustic monitoring 
off of Washington between January and June 2011, with an absence of 
calls from mid-July through November 2011 ([Scirc]irovi[cacute] et al., 
2012b in Navy 2015). Analysis of these data suggest that this species 
could be more than twice as prevalent in this area as Baird's beaked 
whale (Baumann-Pickering et al., 2014). At least five stranding records 
exist for British Columbia (Houston 1990b; Willis and Baird 1998; Ford 
2014), including two strandings on the west coast of Haida Gwaii and 
two strandings on the west coast of Vancouver Island (Ford 2014). A 
possible sighting has been reported on the east coast of Vancouver 
Island (Ford 2014).

Bottlenose Dolphin

    The bottlenose dolphin is distributed worldwide in coastal and 
shelf waters of tropical and temperate oceans (Jefferson et al. 2015). 
There are two distinct bottlenose dolphin types: a shallow water type, 
mainly found in coastal waters, and a deep water type, mainly found in 
oceanic waters (Duffield et al. 1983; Hoelzel et al. 1998; Walker et 
al. 1999). Coastal common bottlenose dolphins exhibit a range of 
movement patterns including seasonal migration, year-round residency, 
and a combination of long-range movements and repeated local residency 
(Wells and Scott 2009).
    Bottlenose dolphins occur frequently off the coast of California, 
and sightings have been made as far north as 41[deg] N, but few records 
exist for Oregon and Washington (Caretta et al., 2019a). Three 
sightings and one stranding of bottlenose dolphins have been documented 
in Puget Sound since 2004 (Cascadia Research 2011 in Navy 2015). During 
surveys off the U.S. West Coast, offshore bottlenose dolphins were 
generally found at distances greater than 1.86 miles (3 km) from the 
coast and were most abundant off southern California (Barlow, 2010, 
2016). Based on sighting data collected by SWFSC during systematic 
surveys in the Northeast Pacific between 1986 and 2005, there were few 
sightings of offshore bottlenose dolphins north of about 40[deg] N 
(Hamilton et al., 2009). Bottlenose dolphins occur frequently off the 
coast of California, and sightings have been made as far north as 
41[deg] N, but few records exist for Oregon/Washington (Carretta et al. 
2017). It is possible that bottlenose dolphins from the California/
Oregon/Washington Offshore stock may range as far north as the proposed 
survey area during warm-water periods (Caretta et al., 2019a). Adams et 
al. (2014) recorded one sighting off Washington in September 2012. 
There are no confirmed records of bottlenose dolphins in British 
Columbia, though an unconfirmed record exists for offshore waters 
(Baird et al., 1993).

Striped Dolphin

    The striped dolphin has a cosmopolitan distribution in tropical to 
warm temperate waters (Perrin et al. 1994) and is generally seen south 
of 43[deg] N (Archer 2009). However, in the eastern North Pacific, its 
distribution extends as far north as Washington (Jefferson et al., 
2015). The striped dolphin is typically found in waters outside the 
continental shelf and is often associated with convergence zones and 
areas of upwelling (Archer 2009). However, it has also been observed 
approaching shore where there is deep 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 nmi (Caretta et al., 2019a). 
Striped dolphin encounters increase in deep, relatively warmer waters 
off the U.S. West Coast, and their abundance decreases north of

[[Page 19591]]

about 42[deg]N (Barlow et al., 2009; Becker et al., 2012b; Becker et 
al., 2016; Forney et al., 2012). However, few sightings have been made 
off Oregon, and no sightings have been reported for Washington (Caretta 
et al., 2019a) but strandings have occurred along the coasts of both 
Washington and Oregon (Caretta et al., 2016). Striped dolphins are rare 
and considered extralimital in British Columbia (Ford 2014). There are 
a total of 14 confirmed records of stranded individuals or remains for 
Vancouver Island (Ford 2014). A single confirmed sighting was made in 
September 2019 in the Strait of Juan de Fuca (Pacific Whale Watch 
Association 2019).

Common Dolphin

    The common dolphin is found in tropical and warm temperate oceans 
around the world (Perrin 2009). It ranges as far south as 40[deg] S in 
the Pacific Ocean, is common in coastal waters 200-300 m deep and is 
also associated with prominent underwater topography, such as seamounts 
(Evans 1994). Common dolphins have been sighted as far as 550 km from 
shore (Barlow et al. 1997).
    The distribution of common dolphins along the U.S. West Coast is 
variable and likely related to oceanographic changes (Heyning and 
Perrin 1994; Forney and Barlow 1998). It is the most abundant cetacean 
off California; some sightings have been made off Oregon, in offshore 
waters (Carretta et al., 2017). During surveys off the west coast in 
2014 and 2017, sightings were made as far north as 44[deg] N (Barlow 
2016; SIO n.d.). However, their abundance decreases dramatically north 
of about 40[deg] N (Barlow et al., 2009; Becker et al., 2012c; Becker 
et al., 2016; Forney et al., 2012). Based on the absolute dynamic 
topography of the region, common dolphins could occur in relatively 
high densities off Oregon during July-December (Pardo et al., 2015). In 
contrast, habitat modeling predicted moderate densities of common 
dolphins off the Columbia River mouth during summer, with lower 
densities off southern Oregon (Becker et al. 2014). There are three 
stranding records of common dolphins in British Columbia, including one 
from northwestern Vancouver Island, one from the Strait of Juan de 
Fuca, and one from Hecate Strait (Ford 2014).

Pacific White-Sided Dolphin

    The Pacific white-sided dolphin is found in cool temperate waters 
of the North Pacific from the southern Gulf of California to Alaska. 
Across the North Pacific, it appears to have a relatively narrow 
distribution between 38[deg] N and 47[deg] N (Brownell et al., 1999). 
In the eastern North Pacific Ocean, including waters off Oregon, the 
Pacific white-sided dolphin is one of the most common cetacean species, 
occurring primarily in shelf and slope waters (Green et al., 1993; 
Barlow 2003, 2010). It is known to occur close to shore in certain 
regions, including (seasonally) southern California (Brownell et al., 
1999).
    Results of aerial and shipboard surveys strongly suggest seasonal 
north-south movements of the species between California and Oregon/
Washington; the movements apparently are related to oceanographic 
influences, particularly water temperature (Green et al., 1993; Forney 
and Barlow 1998; Buchanan et al., 2001). During winter, this species is 
most abundant in California slope and offshore areas; as northern 
waters begin to warm in the spring, it appears to move north to slope 
and offshore waters off Oregon/Washington (Green et al., 1992, 1993; 
Forney 1994; Forney et al., 1995; Buchanan et al., 2001; Barlow 2003). 
The highest encounter rates off Oregon and Washington have been 
reported during March-May in slope and offshore waters (Green et al., 
1992). Similarly, Becker et al. (2014) predicted relatively high 
densities off southern Oregon in shelf and slope waters.
    Based on year-round aerial surveys off Oregon/Washington, the 
Pacific white-sided dolphin was the most abundant cetacean species, 
with nearly all (97 percent) sightings occurring in May (Green et al., 
1992, 1993). Barlow (2003) also found that the Pacific white-sided 
dolphin was one of the most abundant marine mammal species off Oregon/
Washington during 1996 and 2001 ship surveys, and it was the second 
most abundant species reported during 2008 surveys (Barlow 2010). Adams 
et al. (2014) reported numerous offshore sightings off Oregon during 
summer, fall, and winter surveys in 2011 and 2012.
    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). One group of 10 Pacific white-sided dolphins was sighted during 
the 2009 ETOMO survey (Holst 2017).
    Pacific white-sided dolphins are common throughout the waters of 
British Columbia, including Dixon Entrance, Hecate Strait, Queen 
Charlotte Sound, the west coast of Haida Gwaii, as well as western 
Vancouver Island, and the mainland coast (Ford 2014). Stacey and Baird 
(1991a) compiled 156 published and unpublished records to 1988 of the 
Pacific white-sided dolphin within the Canadian 320-km extended EEZ. 
These dolphins move inshore and offshore seasonally (Stacey and Baird 
1991a). There were inshore records for all months except July, and 
offshore records from all months except December. Offshore sightings 
were much more common than inshore sightings, especially in June-
October; the mean water depth was ~1,100 m. Ford et al. (2011b) 
reported that most sightings occur in water depths <500 m and within 20 
km from shore.

Northern Right Whale Dolphin

    The northern right whale dolphin is found in cool temperate and 
sub-arctic waters of the North Pacific, from the Gulf of Alaska to near 
northern Baja California, ranging from 30[deg] N to 50[deg] N (Reeves 
et al., 2002). In the eastern North Pacific Ocean, including waters off 
Oregon, the northern right whale dolphin is one of the most common 
marine mammal species, occurring primarily in shelf and slope waters 
~100 to >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[dash]offshore 
and north[dash]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).
    Survey data suggest that, at least in the eastern North Pacific, 
seasonal inshore-offshore and north-south movements are related to prey 
availability, with peak abundance in the Southern California Bight 
during winter and distribution shifting northward into

[[Page 19592]]

Oregon and Washington as water temperatures increase during late spring 
and summer (Barlow, 1995; Becker et al., 2014; Forney et al., 1995; 
Forney & Barlow, 1998; Leatherwood & Walker, 1979). Seven northern 
right whale dolphin sightings (231 animals) were made off Washington/
Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic 
survey (RPS 2012b). There were eight northern right whale dolphin 
sightings (278 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).
    There are 47 records of northern right whale dolphins from British 
Columbia, mostly in deep water off the west coast of Vancouver Island; 
however, sightings have also been reported in deep water off Haida 
Gwaii (Ford 2014). Most sightings have occurred in water depths over 
900 m (Baird and Stacey 1991a). One group of six northern right whale 
dolphins was seen west of Vancouver Island in water deeper than 2,500 m 
during a survey from Oregon to Alaska (Hauser and Holt 2009).

Risso's Dolphin

    Risso's dolphin is distributed worldwide in temperate and tropical 
oceans (Baird 2009), although it shows a preference for mid-temperate 
waters of the shelf and slope between 30[deg] and 45[deg] N (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[ordm] N. Several sightings were made off southern Oregon during 
surveys in 1991-2014 (Carretta et al., 2017). Sightings during ship 
surveys in summer/fall 2008 were mostly between ~30 and 38[deg] N; none 
were reported in Oregon/Washington (Barlow 2010).Two sightings of 38 
individuals were recorded off Washington from August 2004 to September 
2008 (Oleson et al. 2009). Risso's dolphins were sighted off Oregon, in 
June and October 2011 (Adams et al. 2014). There were three Risso's 
dolphin sightings (31 animals) made during the July 2012 L-DEO seismic 
surveys off southern Washington (RPS 2012a). This species was not 
sighted during the July 2012 L-DEO seismic survey off Oregon (RPS 
2012c), or off Washington/Oregon during the June-July 2012 L-DEO Juan 
de Fuca plate seismic survey (RPS 2012b).
    Risso's dolphin was once considered rare in British Columbia, but 
there have been numerous sightings since the 1970s (Ford 2014). Most 
sightings have been made in Gwaii Haanas National Park Reserve, Haida 
Gwaii, but there have also been sightings in Dixon Entrance, off the 
west coast of Haida Gwaii, Queen Charlotte Sound, and to the west of 
Vancouver Island (Ford 2014).

False Killer Whale

    The false killer whale is found in all tropical and warmer 
temperate oceans, especially in deep, offshore waters (Odell and 
McClune 1999). 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 (Jefferson et al., 2015; Baird 
2018b). It is gregarious and forms strong social bonds, as is evident 
from its propensity to strand en masse (Baird 2018b). In the eastern 
North Pacific, it has been reported only rarely north of Baja 
California (Leatherwood et al., 1982, 1987; Mangels and Gerrodette 
1994); however, the waters off the U.S. West Coast all the way north to 
Alaska are considered part of its secondary range (Jefferson et al. 
2015).
    Its occurrence in Washington/Oregon is associated with warm-water 
incursions (Buchanan et al., 2001). One pod of false killer whales 
occurred in Puget Sound for several months during the 1990s (USN 2015). 
Two were reported stranded along the Washington coast between 1930-
2002, both in El Ni[ntilde]o years (Norman et al. 2004). One sighting 
was made off southern California during 2014 (Barlow 2016).
    Stacey and Baird (1991b) suggested that false killer whales are at 
the limit of their distribution in Canada and have always been rare. 
Sightings have been made along the northern and central mainland coast 
of British Columbia, as well as in Queen Charlotte Strait, Strait of 
Georgia, and along the west coast of Vancouver Island (Ford 2014).

Killer Whale

    The killer whale is cosmopolitan and globally fairly abundant; it 
has been observed in all oceans of the world (Ford 2009). It is very 
common in temperate waters and also frequents tropical waters, at least 
seasonally (Heyning and Dahlheim 1988). 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 
(Caretta 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 al., 2008).
    Currently, there are eight killer whale stocks recognized in the 
U.S. Pacific: (1) Alaska Residents, occurring from southeast Alaska to 
the Aleutians and Bering Sea; (2) Northern Residents, from BC through 
parts of southeast Alaska; (3) Southern Residents, mainly in inland 
waters of Washington State and southern BC; (4) Gulf of Alaska, 
Aleutian Islands, and Bering Sea Transients, from Prince William Sound 
(PWS) through to the Aleutians and Bering Sea; (5) AT1 Transients, from 
PWS through the Kenai Fjords; (6) West Coast Transients, from 
California through southeast Alaska; (7) Offshore, from California 
through Alaska; and (8) Hawaiian (Carretta et al. 2018). Individuals 
from the Southern Resident, Northern Resident, West Coast Transient, 
and Offshore stocks could be encountered in the proposed project area. 
All three pods (J, K, and L pods) of Southern Resident killer whales 
may occur in the project area.
    Southern Resident killer whales mainly feed on salmon, in 
particular Chinook (Oncorhynchus tshawytscha), but also prey upon other 
salmonids, such as chum (O. keta), coho (O. kitsutch), and steelhead 
(O. mykiss), as well as rockfish (Sebastes spp.), Pacific

[[Page 19593]]

halibut (Hippoglossus stenolepis), Pacific herring (Clupea pallasi), 
among others. Seasonal and spatial shifts in prey consumption have been 
observed, with Chinook consumed in May through September, and chum 
eaten in the fall. Chinook remain an important prey item while the 
Southern Residents are in offshore coastal waters, where they also 
consume a greater diversity of fish species (NMFS 2019).
    Southern Resident killer whales occur for part of the year in the 
inland waterways of the Salish Sea, including Puget Sound, the Strait 
of Juan de Fuca, and the southern Strait of Georgia mostly during the 
spring, summer, and fall. Their movement patterns appear related to the 
seasonal availability of prey, especially Chinook salmon. They also 
move to coastal waters, primarily off Washington and British Columbia, 
in search of suitable prey, and have been observed as far as central 
California and southeast Alaska (NMFS 2019). Although less is known 
about the whales' movements in outer coastal waters than inland waters 
of the Salish Sea, satellite tagging, opportunistic sighting, and 
acoustic recording data suggest that Southern Residents spend nearly 
all their time on the continental shelf, within 34 km of shore in water 
less than 200 m deep (Hanson et al., 2017).
    The Southern Resident DPS was listed as endangered under the ESA in 
2005 after a nearly 20 percent decline in abundance between 1996 and 
2001 (70 FR 69903; November 18, 2005). As compared to stable or growing 
populations, the DPS reflects lower fecundity and has demonstrated 
little to no growth in recent decades, and in fact has declined further 
since the date of listing (NMFS 2019). The population abundance listed 
in the draft 2019 SARs is 75, from the July 1, 2018 annual census 
conducted by the Center for Whale Research (CWR) (Caretta et al., 
2019); since that date, four whales have died or are presumed dead, and 
two calves were born in 2019, bringing the abundance to 73 whales (NMFS 
2019). An additional adult male is considered missing as of January 
2020 (CWR 2020). NMFS has identified three main causes of the 
population decline: (1) Reduced quantity and quality of prey; (2) 
persistent organic pollutants that could cause immune or reproductive 
system dysfunction; and (3) noise and disturbance from increased 
commercial and recreational vessel traffic (NMFS 2019).
    The U.S. Southern Resident killer whale critical habitat designated 
under the ESA currently includes inland waters of Washington relative 
to a contiguous shoreline delimited by the line at a depth of 6.1 m 
relative to extreme high water (71 FR 69054; November 29, 2006). On 
September 19, 2019, NMFS published a proposed rule to revise designated 
Southern Resident killer whale critical habitat to include 40,472.7 
km\2\ of marine waters between the 6.1-m depth contour and the 200-m 
depth contour from the U.S. international border with Canada south to 
Point Sur, California (84 FR 49214; September 19, 2019). The proposed 
survey tracklines overlap with NMFS' proposed expanded Southern 
Resident critical habitat.
    In Canada, Southern Resident killer whales are listed as Endangered 
under the Species at Risk Act (SARA), and critical habitat has been 
designated in the trans-boundary waters in southern British Columbia, 
including the southern Strait of Georgia, Haro Strait, and Strait of 
Juan de Fuca (SOR/2018-278, December 13, 2018; SOR/2009-68, February 
19, 2009; DFO 2018). The continental shelf waters off southwestern 
Vancouver Island, including Swiftsure and La P[eacute]rouse Banks have 
also been designated as critical habitat (DFO 2018). Two of the 
proposed survey tracklines intersect the Canadian Southern Resident 
critical habitat on Swiftsure and La P[eacute]rouse Banks.
    Northern Resident killer whales are not listed under the ESA, but 
are listed as threatened under Canada's SARA (DFO 2018). In British 
Columbia, Northern Resident killer whales inhabit the central and 
northern Strait of Georgia, Johnstone Strait, Queen Charlotte Strait, 
the west coast of Vancouver Island, and the entire central and north 
coast of mainland British Columbia (Muto et al., 2019a,b). Northern 
Resident killer whales are also regularly acoustically detected off the 
coast of Washington (Hanson et al., 2017). Canada has designated 
critical habitat for Northern Resident killer whales in Johnstone 
Strait, southeastern Queen Charlotte Strait, western Dixon Entrance 
along the north coast of Graham Island, Haida Gwaii, and Swiftsure and 
La P[eacute]rouse Banks off southwestern Vancouver Island (SOR/2018-
278, December 13, 2018; SOR/2009-68, February 19, 2009; DFO 2018). 
Critical habitat for both Northern and Southern Resident killer whales 
has been established within the proposed survey area at Swiftsure and 
La P[eacute]rouse Banks (SOR/2018-278, December 13, 2018).
    The main diet of transient killer whales consists of marine 
mammals, in particular porpoises and seals. West coast transient whales 
(also known as Bigg's killer whales) range from Southeast Alaska to 
California (Muto et al., 2019a). The seasonal movements of transients 
are largely unpredictable, although there is a tendency to investigate 
harbor seal haulouts off Vancouver Island more frequently during the 
pupping season in August and September (Baird 1994; Ford 2014). 
Transients have been sighted throughout British Columbia waters, 
including the waters around Vancouver Island (Ford 2014).
    Little is known about offshore killer whales, but they occur 
primarily over shelf waters and feed on fish, especially sharks (Ford 
2014). Dalheim et al. (2008) reported sightings in southeast Alaska 
during spring and summer. Relatively few sightings of offshore killer 
whales have been reported in British Columbia; there have been 103 
records since 1988 (Ford 2014). The number of sightings are likely 
influenced by the fact that these whales prefer deeper waters near the 
continental slope, where little sighting effort has taken place (Ford 
2014). Most sightings are from Haida Gwaii and 15 km or more off the 
west coast of Vancouver Island near the continental slope (Ford et al., 
1994). Offshore killer whales are mainly seen off British Columbia 
during summer, but they can occur in British Columbia year-round (Ford 
2014).

Short-Finned Pilot Whale

    The short-finned pilot whale is found in tropical, subtropical, and 
warm temperate waters (Olson 2009); it is seen as far south as ~40[deg] 
S and as far north as ~50[deg] N (Jefferson et al. 2015). Pilot whales 
are generally nomadic, but may be resident in certain locations, 
including California and Hawaii (Olson 2009). Short-finned pilot whales 
were common off southern California (Dohl et al. 1980) until an El 
Ni[ntilde]o event occurred in 1982-1983 (Carretta et al. 2017).
    Few sightings were made off California/Oregon/Washington in 1984-
1992 (Green et al. 1992; Carretta and Forney 1993; Barlow 1997), and 
sightings remain rare (Barlow 1997; Buchanan et al. 2001; Barlow 2010). 
No short-finned pilot whales were seen during surveys off Oregon and 
Washington in 1989-1990, 1992, 1996, and 2001 (Barlow 2003). A few 
sightings were made off California during surveys in 1991-2014 (Barlow 
2010). Carretta et al. (2019a) reported one sighting off Oregon during 
1991-2014. Several stranding events in Oregon/southern Washington have 
been recorded over the past few decades, including in

[[Page 19594]]

March 1996, June 1998, and August 2002 (Norman et al. 2004).
    Short-finned pilot whales are considered rare in British Columbia 
waters (Baird and Stacey 1993; Ford 2014). There are 10 confirmed 
records, including three bycatch records in offshore waters, six 
sightings in offshore waters, and one stranding; the stranding occurred 
in the Strait of Juan de Fuca (Ford 2014). There are also unconfirmed 
records for nearshore waters of western Vancouver Island (Baird and 
Stacey 1993; Ford 2014).

Harbor Porpoise

    The harbor porpoise inhabits temperate, subarctic, and arctic 
waters. It is typically found in shallow water (<100 m) nearshore but 
is occasionally sighted in deeper offshore water (Jefferson et al., 
2015); abundance declines linearly as depth increases (Barlow 1988). In 
the eastern north Pacific, its range extends from Point Barrow, Alaska 
to Point Conception, California. Their seasonal movements appear to be 
inshore-offshore, rather than north-south, as a response to the 
abundance and distribution of food resources (Dohl et al., 1983; Barlow 
1988). Genetic testing has also shown that harbor porpoises along the 
west coast of North America are not migratory and occupy restricted 
home ranges (Rosel et al., 1995).
    Based on genetic data and density discontinuities, six stocks have 
been identified in California/Oregon/Washington: (1) Washington Inland 
Waters, (2) Northern Oregon/Washington Coast, (3) Northern California/
Southern Oregon, (4) San Francisco-Russian River, (5) Monterey Bay, and 
(6) Morro Bay (Caretta et al., 2019a). Harbor porpoises form the 
Northern Oregon/Washington and the Northern California/Southern Oregon 
stocks could occur in the proposed project area (Caretta et al., 
2019a).
    Harbor porpoises inhabit coastal Oregon and Washington waters year-
round, although there appear to be distinct seasonal changes in 
abundance there (Barlow 1988; Green et al., 1992). Green et al. (1992) 
reported that encounter rates were similarly high during fall and 
winter, intermediate during spring, and low during summer. Encounter 
rates were highest along the Oregon/Washington coast in the area from 
Cape Blanco (~43[deg] N) to California, from fall through spring. 
During summer, the reported encounter rates decreased notably from 
inner shelf to offshore waters. Green et al. (1992) reported that 96 
percent of harbor porpoise sightings off Oregon/Washington occurred in 
coastal waters <100 m deep, with a few sightings on the slope near the 
200-m isobath. Similarly, predictive density distribution maps show the 
highest in nearshore waters along the coasts of Oregon/Washington, with 
very low densities beyond the 500-m isobath (Menza et al., 2016).
    There were no harbor porpoise sightings made during the July 2012 
L-DEO seismic surveys off southern Washington (RPS 2012a), the July 
2012 L-DEO seismic survey off Oregon (RPS 2012c), or off Washington/
Oregon during the June-July 2012 L-DEO Juan de Fuca plate seismic 
survey (RPS 2012b).
    Harbor porpoises are found along the coast of British Columbia 
year-round, primarily in coastal shallow waters, harbors, bays, and 
river mouths (Osborne et al., 1988), but can also be found in deep 
water over the continental shelf and over offshore banks that are no 
deeper than 150 m (Ford 2014; COSEWIC 2016). Many sightings records 
exist for nearshore waters of Vancouver Island, and occasional 
sightings have also been made in shallow water of Swiftsure and La 
P[eacute]rouse banks off southwestern Vancouver Island (Ford 2014).

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; Carretta et al. 2018). Combined 
results of various surveys out to ~550 km offshore indicate that the 
distribution and abundance of Dall's porpoise varies between seasons 
and years. North-south movements are believed to occur between Oregon/
Washington and California in response to changing oceanographic 
conditions, particularly temperature and distribution and abundance of 
prey (Green et al. 1992, 1993; Mangels and Gerrodette 1994; Barlow 
1995; Forney and Barlow 1998; Buchanan et al. 2001). Becker et al. 
(2014) predicted high densities off southern Oregon throughout the 
year, with moderate densities to the north. According to predictive 
density distribution maps, the highest densities off southern 
Washington and Oregon occur along the 500-m isobath (Menza et al. 
2016).
    Encounter rates reported by Green et al. (1992) during aerial 
surveys off Oregon/Washington were highest in fall, lowest during 
winter, and intermediate during spring and summer. Encounter rates 
during the summer were similarly high in slope and shelf waters, and 
somewhat lower in offshore waters (Green et al. 1992). Dall's porpoise 
was the most abundant species sighted off Oregon/Washington during 
1996, 2001, 2005, and 2008 ship surveys up to ~550 km from shore 
(Barlow 2003, 2010). Oleson et al. (2009) reported 44 sightings of 206 
individuals off Washington during surveys from August 2004 to September 
2008. Dall's porpoise were seen in the waters off Oregon during summer, 
fall, and winter surveys in 2011 and 2012 (Adams et al., 2014). 
Nineteen Dall's porpoise sightings (144 animals) were made off 
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate 
seismic survey (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).
    Dall's porpoise is found all along the coast of British Columbia 
and is common inshore and offshore throughout the year (Jefferson 1990; 
Ford 2014). It is most common over the continental shelf and slope, but 
also occurs >2,400 km from the coast (Pike and MacAskie 1969 in 
Jefferson 1990), and sightings have been made throughout the proposed 
survey area (Ford 2014). During a survey from Oregon to Alaska, Dall's 
porpoises were sighted west of Vancouver Island and Haida Gwaii in 
early October during the southbound transit, but none were sighted in 
mid-September during the northward transit; all sightings were made in 
water deeper than 2000 m (Hauser and Holst 2009).

Guadalupe Fur Seal

    Guadalupe fur seals were once plentiful on the California coast, 
ranging from the Gulf of the Farallones near San Francisco, to the 
Revillagigedo Islands, Mexico (Aurioles-Gamboa et al., 1999), but they 
were over-harvested in the 19th century to near extinction. After being 
protected, the population grew slowly; mature individuals of the 
species were observed occasionally in the Southern California Bight 
starting in the 1960s (Stewart et al., 1993), and, in 1997, a

[[Page 19595]]

female and pup were observed on San Miguel Island (Melin & DeLong, 
1999). Since 2008, individual adult females, subadult males, and 
between one and three pups have been observed annually on San Miguel 
Island (Caretta et al., 2017).
    During the summer breeding season, most adults occur at rookeries 
in Mexico (Caretta et al., 2019a,b; Norris 2017 in Navy 2019a,b). 
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 2,375 km (Ronald and Gots 2003). 
Several rehabilitated Guadalupe fur seals that were satellite tagged 
and released in central California traveled as far north as British 
Columbia (Norris et al., 2015; Norris 2017 in Navy 2019a,b). Fur seals 
younger than two years old are more likely to travel to more northerly, 
offshore areas than older fur seals (Norris 2017 in Navy 2019a,b). 
Stranding data also indicates that fur seals younger than two years old 
are more likely to occur in the proposed survey area, as this age class 
was most frequently reported (Lambourn et al., 2012 in Navy 2019a,b). 
Guadalupe fur seals have not been observed in previous L-DEO surveys in 
the northeast Pacific (RPS 2012a,b,c).
    Increased strandings of Guadalupe fur seals have occurred along the 
entire coast of California. Guadalupe fur seal strandings began in 
January 2015 and were eight times higher than the historical average. 
Strandings have continued since 2015 and have remained well above 
average through 2019. Strandings are seasonal and generally peak in 
April through June of each year. Strandings in Oregon and Washington 
became elevated starting in 2019 and have continued to present. 
Strandings in these two states in 2019 are five times higher than the 
historical average. Guadalupe fur seals have stranded alive and dead. 
Those stranding are mostly weaned pups and juveniles (1-2 years old). 
The majority of stranded animals showed signs of malnutrition with 
secondary bacterial and parasitic infections. NMFS has declared a UME 
for Guadalupe fur seals along the entire U.S. West Coast; the UME is 
ongoing and NMFS is continuing to investigate the cause(s). For 
additional information on the UME, see https://www.fisheries.noaa.gov/national/marine-life-distress/2015-2020-guadalupe-fur-seal-unusual-mortality-event-california.

Northern Fur Seal

    The northern fur seal is endemic to the North Pacific Ocean and 
occurs from southern California to the Bering Sea, Sea of Okhotsk, and 
Sea of Japan (Jefferson et al. 2015). The worldwide population of 
northern fur seals has declined substantially from 1.8 million animals 
in the 1950s (Muto et al. 2018). They were subjected to large-scale 
harvests on the Pribilof Islands to supply a lucrative fur trade. Two 
stocks are recognized in U.S. waters: The Eastern North Pacific and the 
California stocks. The Eastern Pacific stock ranges from southern 
California during winter to the Pribilof Islands and Bogoslof Island in 
the Bering Sea during summer (Carretta et al. 2018; Muto et al. 2018). 
Abundance of the Eastern Pacific Stock has been decreasing at the 
Pribilof Islands since the 1940s and increasing on Bogoslof Island. The 
California stock originated with immigrants from the Pribilof Islands 
and Russian populations that recolonized San Miguel Island during the 
late 1950s or early 1960s after northern fur seals were extirpated from 
California in the 1700s and 1800s (DeLong 1982). The northern fur seal 
population appears to be greatly affected by El Ni[ntilde]o events. In 
the month of June, approximately 93.6 percent of the northern fur seals 
in the survey area are expected to be from the Eastern Pacific stock 
and 6.4 percent from the California stock (U.S. Navy 2019). Therefore, 
although individuals from both the Eastern Pacific Stock and California 
Stock may be present in the proposed survey area, the majority are 
expected to be from the Eastern Pacific Stock.
    Most northern fur seals are highly migratory. During the breeding 
season, most of the world's population of northern fur seals occurs on 
the Pribilof and Bogoslof islands (NMFS 2007). The main breeding season 
is in July (Gentry 2009). Adult males usually occur onshore from May to 
August, though some may be present until November; females are usually 
found ashore from June to November (Muto et al. 2018). Nearly all fur 
seals from the Pribilof Island rookeries are foraging at sea from fall 
through late spring. In November, females and pups leave the Pribilof 
Islands and migrate through the Gulf of Alaska to feeding areas 
primarily off the coasts of BC, Washington, Oregon, and California 
before migrating north again to the rookeries in spring (Ream et al. 
2005; Pelland et al. 2014). Immature seals can remain in southern 
foraging areas year-round until they are old enough to mate (NMFS 
2007). Adult males migrate only as far south as the Gulf of Alaska or 
to the west off the Kuril Islands (Kajimura 1984). Pups from the 
California stock also migrate to Washington, Oregon, and northern 
California after weaning (Lea et al. 2009). Although pups may be 
present, there are no rookeries in Washington or Oregon.
    The northern fur seals spends ~90 percent of its time at sea, 
typically in areas of upwelling along the continental slopes and over 
seamounts (Gentry 1981). The remainder of its life is spent on or near 
rookery islands or haulouts. While at sea, northern fur seals usually 
occur singly or in pairs, although larger groups can form in waters 
rich with prey (Antonelis and Fiscus 1980; Gentry 1981). Northern fur 
seals dive to relatively shallow depths to feed: 100-200 m for females, 
and <400 m for males (Gentry 2009). Tagged adult female fur seals were 
shown to remain within 200 km of the shelf break (Pelland et al. 2014).
    Bonnell et al. (1992) noted the presence of northern fur seals 
year-round off Oregon/Washington, with the greatest numbers (87 
percent) occurring in January-May. Northern fur seals were seen as far 
out from the coast as 185 km, and numbers increased with distance from 
land; they were 5-6 times more abundant in offshore waters than over 
the shelf or slope (Bonnell et al. 1992). The highest densities were 
seen in the Columbia River plume (~46[deg] N) and in deep offshore 
waters (>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). Tagged adult fur 
seals were tracked from the Pribilof Islands to the waters off 
Washington/Oregon/California, with recorded movement throughout the 
proposed survey area (Pelland et al. 2014).
    Thirty-one northern fur seal sightings (63 animals) were made off 
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate 
seismic survey (RPS 2012b). There were six sightings (6 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).
    Off British Columbia, females and subadult males are typically 
found during the winter off the continental shelf (Bigg 1990). They 
start arriving from Alaska during December and most will leave British 
Columbia waters by July (Ford 2014). Ford (2014) also reported the 
occurrence of northern fur seals throughout British Columbia, including 
Dixon Entrance, Hecate Strait, Queen Charlotte Sound, and off the west

[[Page 19596]]

coasts of Haida Gwaii and Vancouver Island, with concentrations over 
the shelf and slope, especially on La P[eacute]rouse Bank, southwestern 
Vancouver Island. A few animals are seen in inshore waters in British 
Columbia, and individuals occasionally come ashore, usually at sea lion 
haulouts (e.g., Race Rocks, off southern Vancouver Island) during 
winter and spring (Baird and Hanson 1997). Although fur seals sometimes 
haul out in British Columbia, there are no breeding rookeries.

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 2019d). 
There are two stocks and DPSs of Steller sea lions, the Western and 
Eastern DPSs, which are divided at 144[deg] W longitude (Muto et al., 
2019b). The Western DPS is listed as endangered under the ESA and 
includes animals that occur in Japan and Russia (Muto et al., 2019a,b); 
the Eastern DPS is not listed. Only individuals from the Eastern DPS 
are expected to occur in the proposed survey area.
    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). The 
eastern stock of Steller sea lions has historically bred on rookeries 
located in Southeast Alaska, British Columbia, Oregon, and California. 
However, within the last several years a new rookery has become 
established on the outer Washington coast (at the Carroll Island and 
Sea Lion Rock complex), with >100 pups born there in 2015 (Muto et al., 
2018). 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 2019e). 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).
    Non-breeding adults use haulouts or occupy sites at the periphery 
of rookeries during the breeding season (NMFS 2008). Pupping occurs 
from mid-May to mid-July (Pitcher and Calkins 1981) and peaks in June 
(Pitcher et al., 2002). Territorial males fast and remain on land 
during the breeding season (NMFS 2008). Females with pups generally 
stay within 30 km of the rookeries in shallow (30-120 m) water when 
feeding (NMFS 2008). Tagged juvenile sea lions showed localized 
movements near shore (Briggs et al., 2005). Loughlin et al. (2003) 
reported that most (88 percent) at-sea movements of juvenile Steller 
sea lions were short (< 15 km) foraging trips. 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 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).
    In British Columbia there are six main rookeries which are situated 
at the Scott Islands off northwestern Vancouver Island, the Kerourd 
Islands near Cape St. James at the southern end of Haida Gwaii, North 
Danger Rocks in eastern Hecate Strait, Virgin Rocks in eastern Queen 
Charlotte Sound, Garcin Rocks off southeastern Moresby Island in Haida 
Gwaii, and Gosling Rocks on the central mainland coast (Ford 2014). The 
Scott Islands and Cape St. James rookeries are the two largest breeding 
sites with 4,000 and 850 pups born in 2010, respectively (Ford 2014). 
Some adults and juveniles are also found on sites known as year-round 
haulouts during the breeding season. Haulouts are located along the 
coasts of Haida Gwaii, the central and northern mainland coast, the 
west coast of Vancouver Island, and the Strait of Georgia; some are 
year-round sites whereas others are only winter haulouts (Ford 2014). 
Pitcher et al. (2007) reported 24 major haulout sites (>50 sea lions) 
in British Columbia, but there are currently around 30 (Ford 2014). The 
total pup and non-pup count of Steller sea lions in British Columbia in 
2002 was 15,438; this represents a minimum population estimate (Pitcher 
et al., 2007). The highest pup counts in British Columbia occur in July 
(Bigg 1988).

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 
British Columbia 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.
    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 British Columbia (Lowry et al., 1992). 
They remain there until spring (March-May), when they migrate back to 
the breeding colonies (Lowry et al., 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). Peak numbers of California sea 
lions off Oregon and Washington occur during the fall (Bonnell et al., 
1992). California sea lions have not been observed in previous L-DEO 
surveys in the northeast Pacific (RPS 2012a,b,c).
    California sea lions used to be rare in British Columbia, but their 
numbers have increased substantially since the 1970s and 1980s (Ford 
2014). Wintering California sea lion numbers have increased off 
southern Vancouver Island since the 1970s, likely as a result of the 
increasing California breeding population (Olesiuk and Bigg 1984). 
Several thousand occur in the waters of British Columbia from fall to 
spring (Ford 2014). Adult and subadult male California sea lions are 
mainly seen in British Columbia during the winter (Olesiuk and Bigg 
1984). They are mostly seen off the west coast of Vancouver Island and 
in the Strait of Georgia, but they are also known to haul out along the 
coasts of Haida Gwaii, including Dixon Entrance, and the mainland (Ford 
2014).
    Elevated strandings of California sea lion pups have occurred in 
Southern California since January 2013 and NMFS has declared a UME. The 
UME is confined to pup and yearling California sea lions, many of which 
are emaciated, dehydrated, and underweight for their age. A change in 
the availability of sea

[[Page 19597]]

lion prey, especially sardines, a high value food source for nursing 
mothers, is a likely contributor to the large number of strandings. 
Sardine spawning grounds shifted further offshore in 2012 and 2013, and 
while other prey were available (market squid and rockfish), these may 
not have provided adequate nutrition in the milk of sea lion mothers 
supporting pups, or for newly-weaned pups foraging on their own. 
Although the pups showed signs of some viruses and infections, findings 
indicate that this event was not caused by disease, but rather by the 
lack of high quality, close-by food sources for nursing mothers. 
Current evidence does not indicate that this UME was caused by a single 
infectious agent, though a variety of disease-causing bacteria and 
viruses were found in samples from sea lion pups. Investigating and 
identifying the cause of this UME is a true public-private effort with 
many collaborators. The investigative team examined multiple potential 
explanations for the high numbers of malnourished California sea lion 
pups observed on the island rookeries and stranded on the mainland in 
2013. The UME investigation is ongoing. For more information, see 
https://www.fisheries.noaa.gov/national/marine-life-distress/2013-2017-california-sea-lion-unusual-mortality-event-california.

Northern Elephant Seal

    The northern elephant seal breeds in California and Baja 
California, primarily on offshore islands, from Cedros off the west 
coast of Baja California, north to the Farallons in Central California 
(Stewart et al. 1994). Pupping has also been observed at Shell Island 
(~43.3[deg] N) off southern Oregon, suggesting a range expansion 
(Bonnell et al. 1992; Hodder et al. 1998).
    Adult elephant seals engage in two long northward migrations per 
year, one following the breeding season, and another following the 
annual molt (Stewart and DeLong 1995). Between the two foraging 
periods, they return to land to molt, with females returning earlier 
than males (March-April vs. July-August). After the molt, adults then 
return to their northern feeding areas until the next winter breeding 
season. Breeding occurs from December to March (Stewart and Huber 
1993). Females arrive in late December or January and give birth within 
~1 week of their arrival. Pups are weaned after just 27 days and are 
abandoned by their mothers. Juvenile elephant seals typically leave the 
rookeries in April or May and head north, traveling an average of 900-
1000 km. Hindell (2009) noted that traveling likely takes place at 
depths >200 m. Most elephant seals return to their natal rookeries when 
they start breeding (Huber et al. 1991).
    When not at their breeding rookeries, adults feed at sea far from 
the rookeries. Males may feed as far north as the eastern Aleutian 
Islands and the Gulf of Alaska, whereas females feed south of 45[deg] N 
(Le Boeuf et al. 1993; Stewart and Huber 1993). Adult male elephant 
seals migrate north via the California current to the Gulf of Alaska 
during foraging trips, and could potentially be passing through the 
area off Washington in May and August (migrating to and from molting 
periods) and November and February (migrating to and from breeding 
periods), but likely their presence there is transient and short-lived. 
Adult females and juveniles forage in the California current off 
California to BC (Le Boeuf et al. 1986, 1993, 2000). Bonnell et al. 
(1992) reported that northern elephant seals were distributed equally 
in shelf, slope, and offshore waters during surveys conducted off 
Oregon and Washington, as far as 150 km from shore, in waters >2000 m 
deep. Telemetry data indicate that they range much farther offshore 
than that (Stewart and DeLong 1995).
    Off Washington, most elephant seal sightings at sea were made 
during June, July, and September; off Oregon, sightings were recorded 
from November through May (Bonnell et al. 1992). Several seals were 
seen off Oregon during summer, fall, and winter surveys in 2011 and 
2012 (Adams et al. 2014). Northern elephant seals were also taken as 
bycatch off Oregon in the west coast groundfish fishery during 2002-
2009 (Jannot et al. 2011). Northern elephant seals were sighted five 
times (5 animals) during the July 2012 L-DEO seismic surveys off 
southern Washington (RPS 2012a). This species was not sighted during 
the July 2012 L-DEO seismic survey off Oregon (RPS 2012c), or off 
Washington/Oregon during the June-July 2012 L-DEO Juan de Fuca plate 
seismic survey (RPS 2012b). One northern elephant seal was sighted 
during the 2009 ETOMO survey off of British Columbia (Holst 2017).
    Race Rocks Ecological Preserve, located off southern Vancouver 
Island, is one of the few spots in British Columbia where elephant 
seals regularly haul out. Based on their size and general appearance, 
most animals using Race Rocks are adult females or subadults, although 
a few males also haul out there. Use of Race Rocks by northern elephant 
seals has increased substantially in recent years, most likely as a 
result of the species' dramatic recovery from near extinction in the 
early 20th century and its tendency to be highly migratory. A peak 
number (22) of adults and subadults were observed in spring 2003 
(Demarchi and Bentley 2004); pups have also been born there primarily 
during December and January (Ford 2014). Haulouts can also be found on 
the western and northeastern coasts of Haida Gwaii, and along the 
coasts of Vancouver Island (Ford 2014).

Harbor Seal

    Two subspecies of harbor seal occur in the Pacific: P.v. stejnegeri 
in the northwest Pacific Ocean and P.v. richardii in the eastern 
Pacific Ocean. P.v. richardii occurs in nearshore, coastal, and 
estuarine areas ranging from Baja California, Mexico, north to the 
Pribilof Islands in Alaska (Carretta et al., 2019a). Five stocks of 
harbor seals are recognized along the U.S. West Coast: (1) Southern 
Puget Sound, (2) Washington Northern Inland Waters Stock, (3) Hood 
Canal, (4) Oregon/Washington Coast, and (5) California (Carretta et 
al., 2019a). The Oregon/Washington Coast stock occurs in the proposed 
survey area.
    Harbor seals inhabit estuarine and coastal waters, hauling out on 
rocks, reefs, beaches, and glacial ice flows. They are generally non-
migratory, but move locally with the tides, weather, season, food 
availability, and reproduction (Scheffer and Slipp 1944; Fisher 1952; 
Bigg 1969, 1981). Female harbor seals give birth to a single pup while 
hauled out on shore or on glacial ice flows; pups are born from May to 
mid-July. When molting, which occurs primarily in late August, seals 
spend the majority of the time hauled out on shore, glacial ice, or 
other substrates. Juvenile harbor seals can travel significant 
distances (525 km) to forage or disperse (Lowry et al., 2001). The 
smaller home range used by adults is suggestive of a strong site 
fidelity (Pitcher and Calkins 1979; Pitcher and McAllister 1981; Lowry 
et al., 2001).
    Harbor seals haul out on rocks, reefs, and beaches along the U.S. 
west coast (Carretta et al., 2019a). Jeffries et al. (2000) documented 
several harbor seal rookeries and haulouts along the Washington 
coastline. Bonnell et al. (1992) noted that most harbor seals sighted 
off Oregon and Washington were within 20 km from shore, with the 
farthest sighting 92 km from the coast. Menza et al. (2016) also showed 
the highest predicted densities nearshore. During surveys off the 
Oregon and Washington coasts, 88 percent of at-sea harbor seals 
occurred over shelf waters <200 m deep, with a few sightings near the 
2000-m contour, and only one sighting over deeper water (Bonnell et

[[Page 19598]]

al., 1992). Twelve sightings of harbor seals occurred in nearshore 
waters from R/V Northern Light during a survey off southern Washington 
during July 2012 (RPS 2012a).
    Harbor seals occur along all coastal areas of British Columbia, 
including the western coast of Vancouver Island, with the highest 
concentration in the Strait of Georgia (13.1 seals per km of coast); 
average densities elsewhere are 2.6 seals per km (Ford 2014). Almost 
1,400 haulouts have been reported for British Columbia, many of them in 
the Strait of Georgia (Ford 2014).

Marine Mammal Hearing

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

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

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
31 marine mammal species (25 cetacean and six pinniped (four otariid 
and two phocid) species) have the reasonable potential to co-occur with 
the proposed survey activities. Please refer to Table 1. Of the 
cetacean species that may be present, six are classified as low-
frequency cetaceans (i.e., all mysticete species), 15 are classified as 
mid-frequency cetaceans (i.e., all delphinid and ziphiid species and 
the sperm whale), and four are classified as high-frequency cetaceans 
(i.e., porpoises and Kogia spp.).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section includes a summary and discussion of the ways that 
components of the specified activity may impact marine mammals and 
their habitat. The Estimated Take by Incidental Harassment section 
later in this document includes a quantitative analysis of the number 
of individuals that are expected to be taken by this activity. The 
Negligible Impact Analysis and Determination section considers the 
content of this section, the Estimated Take by Incidental Harassment 
section, and the Proposed Mitigation section, to draw conclusions 
regarding the likely impacts of these activities on the reproductive 
success or survivorship of individuals and how those impacts on 
individuals are likely to impact marine mammal species or stocks.

Description of Active Acoustic Sound Sources

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

[[Page 19599]]

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 the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al., 1995). The result is that, 
depending on the source type and its intensity, sound from a given 
activity may be a negligible addition to the local environment or could 
form a distinctive signal that may affect marine mammals. Details of 
source types are described in the following text.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al. (2007) for an in-depth discussion of these concepts.
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or non-continuous (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems (such as 
those used by the U.S. Navy). The duration of such sounds, as received 
at a distance, can be greatly extended in a highly reverberant 
environment.
    Airgun arrays produce pulsed signals with energy in a frequency 
range from about 10-2,000 Hz, with most energy radiated at frequencies 
below 200 Hz. The amplitude of the acoustic wave emitted from the 
source is equal in all directions (i.e., omnidirectional), but airgun 
arrays do possess some directionality due to different phase delays 
between guns in different directions. Airgun arrays are typically tuned 
to maximize functionality for data acquisition purposes, meaning that 
sound transmitted in horizontal directions and at higher frequencies is 
minimized to the extent possible.

[[Page 19600]]

Acoustic Effects

    Here, we discuss the effects of active acoustic sources on marine 
mammals.
    Potential Effects of Underwater Sound--Please refer to the 
information given previously (``Description of Active Acoustic 
Sources'') regarding sound, characteristics of sound types, and metrics 
used in this document. Note that, in the following discussion, we refer 
in many cases to a review article concerning studies of noise-induced 
hearing loss conducted from 1996-2015 (i.e., Finneran, 2015). For 
study-specific citations, please see that work. Anthropogenic sounds 
cover a broad range of frequencies and sound levels and can have a 
range of highly variable impacts on marine life, from none or minor to 
potentially severe responses, depending on received levels, duration of 
exposure, behavioral context, and various other factors. The potential 
effects of underwater sound from active acoustic sources can 
potentially result in one or more of the following: Temporary or 
permanent hearing impairment, non-auditory physical or physiological 
effects, behavioral disturbance, stress, and masking (Richardson et 
al., 1995; Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 
2007; G[ouml]tz et al., 2009). The degree of effect is intrinsically 
related to the signal characteristics, received level, distance from 
the source, and duration of the sound exposure. In general, sudden, 
high level sounds can cause hearing loss, as can longer exposures to 
lower level sounds. Temporary or permanent loss of hearing will occur 
almost exclusively for noise within an animal's hearing range. We first 
describe specific manifestations of acoustic effects before providing 
discussion specific to the use of airgun arrays.
    Richardson et al. (1995) described zones of increasing intensity of 
effect that might be expected to occur, in relation to distance from a 
source and assuming that the signal is within an animal's hearing 
range. First is the area within which the acoustic signal would be 
audible (potentially perceived) to the animal, but not strong enough to 
elicit any overt behavioral or physiological response. The next zone 
corresponds with the area where the signal is audible to the animal and 
of sufficient intensity to elicit behavioral or physiological 
responsiveness. Third is a zone within which, for signals of high 
intensity, the received level is sufficient to potentially cause 
discomfort or tissue damage to auditory or other systems. Overlaying 
these zones to a certain extent is the area within which masking (i.e., 
when a sound interferes with or masks the ability of an animal to 
detect a signal of interest that is above the absolute hearing 
threshold) may occur; the masking zone may be highly variable in size.
    We describe the more severe effects of certain non-auditory 
physical or physiological effects only briefly as we do not expect that 
use of airgun arrays are reasonably likely to result in such effects 
(see below for further discussion). Potential effects from impulsive 
sound sources can range in severity from effects such as behavioral 
disturbance or tactile perception to physical discomfort, slight injury 
of the internal organs and the auditory system, or mortality (Yelverton 
et al., 1973). Non-auditory physiological effects or injuries that 
theoretically might occur in marine mammals exposed to high level 
underwater sound or as a secondary effect of extreme behavioral 
reactions (e.g., change in dive profile as a result of an avoidance 
reaction) caused by exposure to sound include neurological effects, 
bubble formation, resonance effects, and other types of organ or tissue 
damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack, 
2007; Tal et al., 2015). The survey activities considered here do not 
involve the use of devices such as explosives or mid-frequency tactical 
sonar that are associated with these types of effects.
    Threshold Shift--Marine mammals exposed to high-intensity sound, or 
to lower-intensity sound for prolonged periods, can experience hearing 
threshold shift (TS), which is the loss of hearing sensitivity at 
certain frequency ranges (Finneran, 2015). TS can be permanent (PTS), 
in which case the loss of hearing sensitivity is not fully recoverable, 
or temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Repeated sound exposure that 
leads to TTS could cause PTS. In severe cases of PTS, there can be 
total or partial deafness, while in most cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). In addition, other 
investigators have suggested that TTS is within the normal bounds of 
physiological variability and tolerance and does not represent physical 
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to 
constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several dBs above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al. 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulse sounds (such as airgun pulses as 
received close to the source) are at least 6 dB higher than the TTS 
threshold on a peak-pressure basis and PTS cumulative sound exposure 
level thresholds are 15 to 20 dB higher than TTS cumulative sound 
exposure level thresholds (Southall et al., 2007). Given the higher 
level of sound or longer exposure duration necessary to cause PTS as 
compared with TTS, it is considerably less likely that PTS could occur.
    For mid-frequency cetaceans in particular, potential protective 
mechanisms may help limit onset of TTS or prevent onset of PTS. Such 
mechanisms include dampening of hearing, auditory adaptation, or 
behavioral amelioration (e.g., Nachtigall and Supin, 2013; Miller et 
al., 2012; Finneran et al., 2015; Popov et al., 2016).
    TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. Few data 
on sound levels and durations necessary to elicit mild TTS have been 
obtained for marine mammals.
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS, and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to 
serious. For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that occurs during a time where ambient noise is lower and there 
are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during

[[Page 19601]]

time when communication is critical for successful mother/calf 
interactions could have more serious impacts.
    Finneran et al. (2015) measured hearing thresholds in three captive 
bottlenose dolphins before and after exposure to ten pulses produced by 
a seismic airgun in order to study TTS induced after exposure to 
multiple pulses. Exposures began at relatively low levels and gradually 
increased over a period of several months, with the highest exposures 
at peak SPLs from 196 to 210 dB and cumulative (unweighted) SELs from 
193-195 dB. No substantial TTS was observed. In addition, behavioral 
reactions were observed that indicated that animals can learn behaviors 
that effectively mitigate noise exposures (although exposure patterns 
must be learned, which is less likely in wild animals than for the 
captive animals considered in this study). The authors note that the 
failure to induce more significant auditory effects likely due to the 
intermittent nature of exposure, the relatively low peak pressure 
produced by the acoustic source, and the low-frequency energy in airgun 
pulses as compared with the frequency range of best sensitivity for 
dolphins and other mid-frequency cetaceans.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin, beluga whale, harbor porpoise, and Yangtze finless 
porpoise) exposed to a limited number of sound sources (i.e., mostly 
tones and octave-band noise) in laboratory settings (Finneran, 2015). 
In general, harbor porpoises have a lower TTS onset than other measured 
cetacean species (Finneran, 2015). Additionally, the existing marine 
mammal TTS data come from a limited number of individuals within these 
species. There are no data available on noise-induced hearing loss for 
mysticetes.
    Critical questions remain regarding the rate of TTS growth and 
recovery after exposure to intermittent noise and the effects of single 
and multiple pulses. Data at present are also insufficient to construct 
generalized models for recovery and determine the time necessary to 
treat subsequent exposures as independent events. More information is 
needed on the relationship between auditory evoked potential and 
behavioral measures of TTS for various stimuli. For summaries of data 
on TTS in marine mammals or for further discussion of TTS onset 
thresholds, please see Southall et al. (2007, 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 that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with 
captive marine mammals have showed pronounced behavioral reactions, 
including avoidance of loud sound sources (Ridgway et al., 1997). 
Observed responses of wild marine mammals to loud pulsed sound sources 
(typically seismic airguns or acoustic harassment devices) have been 
varied but often consist of avoidance behavior or other behavioral 
changes suggesting discomfort (Morton and Symonds, 2002; see also 
Richardson et al., 1995; Nowacek et al., 2007). However, many 
delphinids approach acoustic source vessels with no apparent discomfort 
or obvious behavioral change (e.g., Barkaszi et al., 2012).
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely, and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Ng and Leung, 2003; Nowacek et al., 2004; Goldbogen et 
al., 2013a, b). Variations in dive behavior may reflect interruptions 
in biologically significant activities (e.g., foraging) or they may be 
of little biological significance. The impact of an alteration to dive 
behavior resulting from an acoustic exposure depends on what the animal 
is doing at the time of the exposure and the type and magnitude of the 
response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al.;

[[Page 19602]]

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, 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

[[Page 19603]]

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 large arrays of airguns 
(considered to be 500 in\3\ or more) were firing, lateral displacement, 
more localized avoidance, or other changes in behavior were evident for 
most odontocetes. However, significant responses to large arrays were 
found only for the minke whale and fin whale. Behavioral responses 
observed included changes in swimming or surfacing behavior, with 
indications that cetaceans remained near the water surface at these 
times. Cetaceans were recorded as feeding less often when large arrays 
were active. Behavioral observations of gray whales during a seismic 
survey monitored whale movements and respirations pre-, during, and 
post-seismic survey (Gailey et al., 2016). Behavioral state and water 
depth were the best `natural' predictors of whale movements and 
respiration and, after considering natural variation, none of the 
response variables were significantly associated with seismic survey or 
vessel sounds.
    Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficiently to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et

[[Page 19604]]

al., 2004; Lankford et al., 2005). Stress responses due to exposure to 
anthropogenic sounds or other stressors and their effects on marine 
mammals have also been reviewed (Fair and Becker, 2000; Romano et al., 
2002b) and, more rarely, studied in wild populations (e.g., Romano et 
al., 2002a). For example, Rolland et al. (2012) found that noise 
reduction from reduced ship traffic in the Bay of Fundy was associated 
with decreased stress in North Atlantic right whales. These and other 
studies lead to a reasonable expectation that some marine mammals will 
experience physiological stress responses upon exposure to acoustic 
stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al., 1995; Erbe et al., 
2016). Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher intensity, and may occur whether the sound is natural (e.g., 
snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g., 
shipping, sonar, seismic exploration) in origin. The ability of a noise 
source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is man-made, it may be considered harassment 
when disrupting or altering critical behaviors. It is important to 
distinguish TTS and PTS, which persist after the sound exposure, from 
masking, which occurs during the sound exposure. Because masking 
(without resulting in TS) is not associated with abnormal physiological 
function, it is not considered a physiological effect, but rather a 
potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al., 2000; 
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt 
et al., 2009). Masking can be reduced in situations where the signal 
and noise come from different directions (Richardson et al., 1995), 
through amplitude modulation of the signal, or through other 
compensatory behaviors (Houser and Moore, 2014). Masking can be tested 
directly in captive species (e.g., Erbe, 2008), but in wild populations 
it must be either modeled or inferred from evidence of masking 
compensation. There are few studies addressing real-world masking 
sounds likely to be experienced by marine mammals in the wild (e.g., 
Branstetter et al., 2013).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency 
ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand, 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.
    Masking effects of pulsed sounds (even from large arrays of 
airguns) on marine mammal calls and other natural sounds are expected 
to be limited, although there are few specific data on this. Because of 
the intermittent nature and low duty cycle of seismic pulses, animals 
can emit and receive sounds in the relatively quiet intervals between 
pulses. However, in exceptional situations, reverberation occurs for 
much or all of the interval between pulses (e.g., Simard et al. 2005; 
Clark and Gagnon 2006), which could mask calls. Situations with 
prolonged strong reverberation are infrequent. However, it is common 
for reverberation to cause some lesser degree of elevation of the 
background level between airgun pulses (e.g., Gedamke 2011; Guerra et 
al. 2011, 2016; Klinck et al. 2012; Guan et al. 2015), and this weaker 
reverberation presumably reduces the detection range of calls and other 
natural sounds to some degree. Guerra et al. (2016) reported that 
ambient noise levels between seismic pulses were elevated as a result 
of reverberation at ranges of 50 km from the seismic source. Based on 
measurements in deep water of the Southern Ocean, Gedamke (2011) 
estimated that the slight elevation of background levels during 
intervals between pulses reduced blue and fin whale communication space 
by as much as 36-51 percent when a seismic survey was operating 450-
2,800 km away. Based on preliminary modeling, Wittekind et al. (2016) 
reported that airgun sounds could reduce the communication range of 
blue and fin whales 2000 km from the seismic source. Nieukirk et al. 
(2012) and Blackwell et al. (2013) noted the potential for masking 
effects from seismic surveys on large whales.
    Some baleen and toothed whales are known to continue calling in the 
presence of seismic pulses, and their calls usually can be heard 
between the pulses (e.g., Nieukirk et al. 2012; Thode et al. 2012; 
Br[ouml]ker et al. 2013; Sciacca et al. 2016). As noted above, Cerchio 
et al. (2014) suggested that the breeding display of humpback whales 
off Angola could be disrupted by seismic sounds, as singing activity 
declined with increasing received levels. In addition, some cetaceans 
are known to change their calling rates, shift their peak frequencies, 
or otherwise modify their vocal behavior in response to airgun sounds 
(e.g., Di Iorio and Clark 2010; Castellote et al. 2012; Blackwell et 
al. 2013, 2015). The hearing systems of baleen whales are undoubtedly 
more sensitive to low-frequency sounds than are the ears of the small 
odontocetes that have been studied directly (e.g., MacGillivray et al. 
2014). The sounds important to small odontocetes are predominantly at 
much higher frequencies than are the dominant components of airgun 
sounds, thus limiting the potential for masking. In general, masking 
effects of seismic pulses are expected to be minor, given the normally 
intermittent nature of seismic pulses.

[[Page 19605]]

Ship Noise

    Vessel noise from the Langseth could affect marine animals in the 
proposed survey areas. Houghton et al. (2015) proposed that vessel 
speed is the most important predictor of received noise levels, and 
Putland et al. (2017) also reported reduced sound levels with decreased 
vessel speed. Sounds produced by large vessels generally dominate 
ambient noise at frequencies from 20 to 300 Hz (Richardson et al. 
1995). However, some energy is also produced at higher frequencies 
(Hermannsen et al. 2014); low levels of high-frequency sound from 
vessels has been shown to elicit responses in harbor porpoise (Dyndo et 
al. 2015). Increased levels of ship noise have been shown to affect 
foraging by porpoise (Teilmann et al. 2015; Wisniewska et al. 2018); 
Wisniewska et al. (2018) suggest that a decrease in foraging success 
could have long-term fitness consequences.
    Ship noise, through masking, can reduce the effective communication 
distance of a marine mammal if the frequency of the sound source is 
close to that used by the animal, and if the sound is present for a 
significant fraction of time (e.g., Richardson et al. 1995; Clark et 
al. 2009; Jensen et al. 2009; Gervaise et al. 2012; Hatch et al. 2012; 
Rice et al. 2014; Dunlop 2015; Erbe et al. 2015; Jones et al. 2017; 
Putland et al. 2017). In addition to the frequency and duration of the 
masking sound, the strength, temporal pattern, and location of the 
introduced sound also play a role in the extent of the masking 
(Branstetter et al. 2013, 2016; Finneran and Branstetter 2013; Sills et 
al. 2017). Branstetter et al. (2013) reported that time-domain metrics 
are also important in describing and predicting masking. In order to 
compensate for increased ambient noise, some cetaceans are known to 
increase the source levels of their calls in the presence of elevated 
noise levels from shipping, shift their peak frequencies, or otherwise 
change their vocal behavior (e.g., Parks et al. 2011, 2012, 2016a,b; 
Castellote et al. 2012; Melc[oacute]n et al. 2012; Azzara et al. 2013; 
Tyack and Janik 2013; Lu[iacute]s et al. 2014; Sairanen 2014; Papale et 
al. 2015; Bittencourt et al. 2016; Dahlheim and Castellote 2016; 
Gospi[cacute] and Picciulin 2016; Gridley et al. 2016; Heiler et al. 
2016; Martins et al. 2016; O'Brien et al. 2016; Tenessen and Parks 
2016). Harp seals did not increase their call frequencies in 
environments with increased low-frequency sounds (Terhune and Bosker 
2016). Holt et al. (2015) reported that changes in vocal modifications 
can have increased energetic costs for individual marine mammals. A 
negative correlation between the presence of some cetacean species and 
the number of vessels in an area has been demonstrated by several 
studies (e.g., Campana et al. 2015; Culloch et al. 2016).
    Southern Resident killer whales often forage in the company of 
whale watch boats in the waters around the San Juan Islands, 
Washington. These observed behavioral changes have included faster 
swimming speeds (Williams et al., 2002b), less directed swimming paths 
(Williams et al., 2002b; Bain et al., 2006; Williams et al., 2009a), 
and less time foraging (Bain et al., 2006; Williams et al., 2006; 
Lusseau et al., 2009; Giles and Cendak 2010; Senigaglia et al., 2016). 
Vessels in the path of the whales can also interfere with important 
social behaviors such as prey sharing (Ford and Ellis 2006) or nursing 
(Kriete 2007). Williams et al. (2006) found that with the disruption of 
feeding behavior that has been observed in Northern Resident killer 
whales, it is estimated that the presence of vessels could result in an 
18 percent decrease in energy intake.
    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.
    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

[[Page 19606]]

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 4.2 kn (7.8 km/h) while 
towing seismic survey gear (LGL 2018). At this speed, both the 
possibility of striking a marine mammal and the possibility of a strike 
resulting in serious injury or mortality are discountable. At average 
transit speed, the probability of serious injury or mortality resulting 
from a strike is less than 50 percent. However, the likelihood of a 
strike actually happening is again discountable. Ship strikes, as 
analyzed in the studies cited above, generally involve commercial 
shipping, which is much more common in both space and time than is 
geophysical survey activity. Jensen and Silber (2004) summarized ship 
strikes of large whales worldwide from 1975-2003 and found that most 
collisions occurred in the open ocean and involved large vessels (e.g., 
commercial shipping). No such incidents were reported for geophysical 
survey vessels during that time period.
    It is possible for ship strikes to occur while traveling at slow 
speeds. For example, a hydrographic survey vessel traveling at low 
speed (5.5 kn) while conducting mapping surveys off the central 
California coast struck and killed a blue whale in 2009. The State of 
California determined that the whale had suddenly and unexpectedly 
surfaced beneath the hull, with the result that the propeller severed 
the whale's vertebrae, and that this was an unavoidable event. This 
strike represents the only such incident in approximately 540,000 hours 
of similar coastal mapping activity (p = 1.9 x 10-6; 95% CI 
= 0-5.5 x 10-6; NMFS, 2013b). In addition, a research vessel 
reported a fatal strike in 2011 of a dolphin in the Atlantic, 
demonstrating that it is possible for strikes involving smaller 
cetaceans to occur. In that case, the incident report indicated that an 
animal apparently was struck by the vessel's propeller as it was 
intentionally swimming near the vessel. While indicative of the type of 
unusual events that cannot be ruled out, neither of these instances 
represents a circumstance that would be considered reasonably 
foreseeable or that would be considered preventable.
    Although the likelihood of the vessel striking a marine mammal is 
low, we require a robust ship strike avoidance protocol (see ``Proposed 
Mitigation''), which we believe eliminates any foreseeable risk of ship 
strike 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 required mitigation measures, the 
relatively slow speed of the vessel towing gear, the presence of bridge 
crew watching for obstacles at all times (including marine mammals), 
and the presence of marine mammal observers, we believe that the 
possibility of ship strike is discountable and, further, that were a 
strike of a large whale to occur, it would be unlikely to result in 
serious injury or mortality. No incidental take resulting from ship 
strike is anticipated, and this potential effect of the specified 
activity will not be discussed further in the following analysis.
    Stranding--When a living or dead marine mammal swims or floats onto 
shore and becomes ``beached'' or incapable of returning to sea, the 
event is a ``stranding'' (Geraci et al., 1999; Perrin and Geraci, 2002; 
Geraci and Lounsbury, 2005; NMFS, 2007). The legal definition for a 
stranding under the MMPA is that ``(A) a marine mammal is dead and is 
(i) on a beach or shore of the United States; or (ii) in waters under 
the jurisdiction of the United States (including any navigable waters); 
or (B) a marine mammal is alive and is (i) on a beach or shore of the 
United States and is unable to return to the water; (ii) on a beach or 
shore of the United States and, although able to return to the water, 
is in need of apparent medical attention; or (iii) in the waters under 
the jurisdiction of the United States (including any navigable waters), 
but is unable to return to its natural habitat under its own power or 
without assistance.''
    Marine mammals strand for a variety of reasons, such as infectious 
agents, biotoxicosis, starvation, fishery interaction, ship strike, 
unusual oceanographic or weather events, sound exposure, or 
combinations of these stressors sustained concurrently or in series. 
However, the cause or causes of most strandings are unknown (Geraci et 
al., 1976; Eaton, 1979; Odell et al., 1980; Best, 1982). Numerous 
studies suggest that the physiology, behavior, habitat relationships, 
age, or condition of cetaceans may cause them to strand or might pre-
dispose them to strand when exposed to another phenomenon. These 
suggestions are consistent with the conclusions of numerous other 
studies that have demonstrated that combinations of dissimilar 
stressors commonly combine to kill an animal or dramatically reduce its 
fitness, even though one exposure without the other does not produce 
the same result (Chroussos, 2000; Creel, 2005; DeVries et al., 2003; 
Fair and Becker, 2000; Foley et al., 2001; Moberg, 2000; Relyea, 2005a; 
2005b, Romero, 2004; Sih et al., 2004).
    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

[[Page 19607]]

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. 
(2019a2019) suggested that certain species amongst 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 
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

[[Page 19608]]

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 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,

[[Page 19609]]

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 nmi (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. Entanglement in OBSs and OBNs is also not expected to occur. 
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 OBSs and OBNs, on 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 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

[[Page 19610]]

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, 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,

[[Page 19611]]

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

Acoustic Thresholds

    NMFS uses acoustic thresholds that identify the received level of 
underwater sound above which exposed marine mammals would be reasonably 
expected to be behaviorally harassed (equated to Level B harassment) or 
to incur PTS of some degree (equated to Level A harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). NMFS uses a generalized acoustic threshold based 
on received level to estimate the onset of behavioral harassment. NMFS 
predicts that marine mammals are likely to be behaviorally harassed in 
a manner we consider Level B harassment when exposed to underwater 
anthropogenic noise above received levels of 120 dB re 1 [mu]Pa (rms) 
for continuous (e.g., vibratory pile-driving, drilling) and above 160 
dB re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., seismic 
airguns) or intermittent (e.g., scientific sonar) sources. L-DEO's 
proposed activity includes the use of impulsive seismic sources. 
Therefore, the 160 dB re 1 [mu]Pa (rms) criteria is applicable for 
analysis of Level B harassment.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual 
criteria to assess auditory injury (Level A harassment) to five 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise from two different types of sources 
(impulsive or non-impulsive). L-DEO's proposed seismic survey includes 
the use of impulsive (seismic airguns) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

[[Page 19612]]



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

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and acoustic 
propagation modeling.
    L-DEO's modeling methodology is described in greater detail in the 
IHA application (LGL 2019). The proposed 2D survey would acquire data 
using the 36-airgun array with a total discharge volume of 6,600 in\3\ 
at a maximum tow depth of 12 m. L-DEO model results are used to 
determine the 160-dBrms radius for the 36-airgun array in deep water 
(>1,000 m) down to a maximum water depth of 2,000 m. Water depths in 
the project area may be up to 4,400 m, but marine mammals are generally 
not anticipated to dive below 2,000 m (Costa and Williams 1999). 
Received sound levels were predicted by L-DEO's model (Diebold et al., 
2010) which uses ray tracing for the direct wave traveling from the 
array to the receiver and its associated source ghost (reflection at 
the air-water interface in the vicinity of the array), in a constant-
velocity half-space (infinite homogeneous ocean layer, unbounded by a 
seafloor). In addition, propagation measurements of pulses from the 36-
airgun array at a tow depth of 6 m have been reported in deep water 
(approximately 1600 m), intermediate water depth on the slope 
(approximately 600-1100 m), and shallow water (approximately 50 m) in 
the Gulf of Mexico in 2007-2008 (Tolstoy et al. 2009; Diebold et al. 
2010).
    For deep and intermediate-water cases, the field measurements 
cannot be used readily to derive Level A and Level B harassment 
isopleths, as at those sites the calibration hydrophone was located at 
a roughly constant depth of 350-500 m, which may not intersect all the 
sound pressure level (SPL) isopleths at their widest point from the sea 
surface down to the maximum relevant water depth for marine mammals of 
~2,000 m. At short ranges, where the direct arrivals dominate and the 
effects of seafloor interactions are minimal, the data recorded at the 
deep and slope sites are suitable for comparison with modeled levels at 
the depth of the calibration hydrophone. At longer ranges, the 
comparison with the model--constructed from the maximum SPL through the 
entire water column at varying distances from the airgun array--is the 
most relevant.
    In deep and intermediate-water depths, comparisons at short ranges 
between sound levels for direct arrivals recorded by the calibration 
hydrophone and model results for the same array tow depth are in good 
agreement (Fig. 12 and 14 in Appendix H of NSF-USGS, 2011). 
Consequently, isopleths falling within this domain can be predicted 
reliably by the L-DEO model, although they may be imperfectly sampled 
by measurements recorded at a single depth. At greater distances, the 
calibration data show that seafloor-reflected and sub-seafloor-
refracted arrivals dominate, whereas the direct arrivals become weak 
and/or incoherent. Aside from local topography effects, the region 
around the critical distance is where the observed levels rise closest 
to the model curve. However, the observed sound levels are found to 
fall almost entirely below the model curve. Thus, analysis of the Gulf 
of Mexico calibration measurements demonstrates that although simple, 
the L-DEO model is a robust tool for conservatively estimating 
isopleths. For deep water (>1,000 m), L-DEO used the deep-water radii 
obtained from model results down to a maximum water depth of 2,000 m.
    A recent retrospective analysis of acoustic propagation from use of 
the Langseth sources during a 2012 survey off Washington (i.e., in the 
same location) suggests that predicted (modeled) radii (using the same 
approach as that used here) were 2-3 times larger than the measured 
radii in shallow water. (Crone et al., 2014). Therefore, because the 
modeled shallow-water radii were specifically demonstrated to be overly 
conservative for the region in which the current survey is planned, L-
DEO used the received levels from multichannel seismic data collected 
by the Langseth during the 2012 survey to estimate Level B harassment 
radii in shallow (<100 m) and intermediate (100-1,000 m) depths (Crone 
et al., 2014). Streamer data in shallow water collected in 2012 have 
the advantage of including the effects of local and complex subsurface 
geology, seafloor topography, and water column properties, and thus 
allow determination of radii more confidently than using data from 
calibration experiments in the Gulf of Mexico.
    The proposed survey would acquire data with a four-string 6,600-
in\3\ airgun array at a tow depth of 12 m while the data collected in 
2012 were acquired with the same airgun array at a tow depth of 9 m. To 
account for the differences in tow depth between the 2012 survey and 
the proposed 2020 survey, L-DEO calculated a scaling factor using the 
deep water modeling (see Appendix D in L-DEO's IHA application). A 
scaling factor of 1.15 was applied to the measured radii from the 
airgun array towed at 9 m.

[[Page 19613]]

    The estimated distances to the Level B harassment isopleth for the 
Langseth's 36-airgun array are shown in Table 4.

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

    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal hearing groups, were calculated based on 
modeling performed by L-DEO using the NUCLEUS source modeling software 
program and the NMFS User Spreadsheet, described below. The acoustic 
thresholds for impulsive sounds (e.g., airguns) contained in the 
Technical Guidance were presented as dual metric acoustic thresholds 
using both SELcum and peak sound pressure metrics (NMFS 
2018). As dual metrics, NMFS considers onset of PTS (Level A 
harassment) to have occurred when either one of the two metrics is 
exceeded (i.e., metric resulting in the largest isopleth). The 
SELcum metric considers both level and duration of exposure, 
as well as auditory weighting functions by marine mammal hearing group. 
In recognition of the fact that the requirement to calculate Level A 
harassment ensonified areas could be more technically challenging to 
predict due to the duration component and the use of weighting 
functions in the new SELcum thresholds, NMFS developed an 
optional User Spreadsheet that includes tools to help predict a simple 
isopleth that can be used in conjunction with marine mammal density or 
occurrence to facilitate the estimation of take numbers.
    The values for SELcum and peak SPL for the Langseth 
airgun array were derived from calculating the modified far-field 
signature (Table 5). The farfield signature is often used as a 
theoretical representation of the source level. To compute the farfield 
signature, the source level is estimated at a large distance below the 
array (e.g., 9 km), and this level is back projected mathematically to 
a notional distance of 1 m from the array's geometrical center. 
However, when the source is an array of multiple airguns separated in 
space, the source level from the theoretical farfield signature is not 
necessarily the best measurement of the source level that is physically 
achieved at the source (Tolstoy et al. 2009). Near the source (at short 
ranges, distances <1 km), the pulses of sound pressure from each 
individual airgun in the source array do not stack constructively, as 
they do for the theoretical farfield signature. The pulses from the 
different airguns spread out in time such that the source levels 
observed or modeled are the result of the summation of pulses from a 
few airguns, not the full array (Tolstoy et al. 2009). At larger 
distances, away from the source array center, sound pressure of all the 
airguns in the array stack coherently, but not within one time sample, 
resulting in smaller source levels (a few dB) than the source level 
derived from the farfield signature. Because the farfield signature 
does not take into account the large array effect near the source and 
is calculated as a point source, the modified farfield signature is a 
more appropriate measure of the sound source level for distributed 
sound sources, such as airgun arrays. L-DEO used the acoustic modeling 
methodology as used for Level B harassment with a small grid step of 1 
m in both the inline and depth directions. The propagation modeling 
takes into account all airgun interactions at short distances from the 
source, including interactions between subarrays, which are modeled 
using the NUCLEUS software to estimate the notional signature and 
MATLAB software to calculate the pressure signal at each mesh point of 
a grid.
    For a more complete explanation of this modeling approach, please 
see ``Appendix A: Determination of Mitigation Zones'' in the IHA 
application.

                          Table 5--Modeled Source Levels Based on Modified Farfield Signature for the 6,600-in\3\ Airgun Array
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Low frequency                          High frequency     Phocid pinnipeds    Otariid pinnipeds
                                                           cetaceans         Mid frequency         cetaceans         (underwater)        (underwater)
                                                      (Lpk,flat: 219 dB;       cetaceans      (Lpk,flat: 202 dB;  (Lpk,flat: 218 dB;  (Lpk,flat: 232 dB;
                                                         LE,LF,24h: 183   (Lpk,flat: 230 dB;     LE,HF,24h: 155      LE,HF,24h: 185      LE,HF,24h: 203
                                                              dB)          LE,MF,24h: 185 dB          dB)                 dB)                 dB)
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
6,600 in\3\ airgun array (Peak SPLflat).............              252.06              252.65              253.24              252.25              252.52
6,600 in\3\ airgun array (SELcum)...................              232.98              232.84              233.10              232.84              232.08
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In order to more realistically incorporate the Technical Guidance's 
weighting functions over the seismic array's full acoustic band, 
unweighted spectrum data for the Langseth's airgun array (modeled in 1 
Hz bands) was used to make adjustments (dB) to the unweighted spectrum 
levels, by frequency, according to the weighting functions for each 
relevant marine mammal hearing group. These adjusted/weighted spectrum 
levels were then converted to pressures ([mu]Pa) in order to integrate 
them over the entire broadband spectrum, resulting in broadband 
weighted source levels by hearing group that could be directly 
incorporated within the User

[[Page 19614]]

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 (4.2 knots) and 
shot intervals (37.5 m) specific to the planned survey, potential 
radial distances to auditory injury zones were then calculated for 
SELcum thresholds.
    Inputs to the User Spreadsheets in the form of estimated SLs are 
shown in Table 5. User Spreadsheets used by L-DEO to estimate distances 
to Level A harassment isopleths for the 36-airgun array for the surveys 
are shown in Table A-3 in Appendix A of the IHA application. Outputs 
from the User Spreadsheets in the form of estimated distances to Level 
A harassment isopleths for the survey are shown in Table 6. As 
described above, NMFS considers onset of PTS (Level A harassment) to 
have occurred when either one of the dual metrics (SELcum 
and Peak SPLflat) is exceeded (i.e., metric resulting in the 
largest isopleth).

                            Table 6--Modeled Radial Distances (m) to Isopleths Corresponding to Level A Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                               Level A harassment zone (m)
           Source  (volume)                   Threshold        -----------------------------------------------------------------------------------------
                                                                  LF cetaceans      MF cetaceans      HF cetaceans         Phocids          Otariids
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-airgun array (6,600 in\3\)........  SELcum.................             426.9                 0               1.3              13.9                 0
                                       Peak...................              38.9              13.6             268.3              43.7              10.6
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used (e.g., stationary receiver with no vertical or horizontal 
movement in response to the acoustic source), isopleths produced may be 
overestimates to some degree, which will ultimately result in some 
degree of overestimation of Level A harassment. However, these tools 
offer the best way to predict appropriate isopleths when more 
sophisticated modeling methods are not available, and NMFS continues to 
develop ways to quantitatively refine these tools and will 
qualitatively address the output where appropriate. For mobile sources, 
such as the proposed seismic survey, the User Spreadsheet predicts the 
closest distance at which a stationary animal would not incur PTS if 
the sound source traveled by the animal in a straight line at a 
constant speed.
    Auditory injury is unlikely to occur for mid-frequency cetaceans, 
otariid pinnipeds, and phocid pinnipeds given very small modeled zones 
of injury for those species (up to 43.7 m), in context of distributed 
source dynamics. The source level of the array is a theoretical 
definition assuming a point source and measurement in the far-field of 
the source (MacGillivray, 2006). As described by Caldwell and Dragoset 
(2000), an array is not a point source, but one that spans a small 
area. In the far-field, individual elements in arrays will effectively 
work as one source because individual pressure peaks will have 
coalesced into one relatively broad pulse. The array can then be 
considered a ``point source.'' For distances within the near-field, 
i.e., approximately 2-3 times the array dimensions, pressure peaks from 
individual elements do not arrive simultaneously because the 
observation point is not equidistant from each element. The effect is 
destructive interference of the outputs of each element, so that peak 
pressures in the near-field will be significantly lower than the output 
of the largest individual element. Here, the 230 dB peak isopleth 
distances would in all cases be expected to be within the near-field of 
the array where the definition of source level breaks down. Therefore, 
actual locations within this distance of the array center where the 
sound level exceeds 230 dB peak SPL would not necessarily exist. In 
general, Caldwell and Dragoset (2000) suggest that the near-field for 
airgun arrays is considered to extend out to approximately 250 m.
    In order to provide quantitative support for this theoretical 
argument, we calculated expected maximum distances at which the near-
field would transition to the far-field (Table 5). For a specific array 
one can estimate the distance at which the near-field transitions to 
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN07AP20.001

with the condition that D >> [lambda], and where D is the distance, L 
is the longest dimension of the array, and [lambda] is the wavelength 
of the signal (Lurton, 2002). Given that [lambda] can be defined by:
[GRAPHIC] [TIFF OMITTED] TN07AP20.002

where f is the frequency of the sound signal and v is the speed of the 
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN07AP20.003

and calculate D directly given a particular frequency and known speed 
of sound (here assumed to be 1,500 meters per second in water, although 
this varies with environmental conditions).
    To determine the closest distance to the arrays at which the source 
level predictions in Table 5 are valid (i.e., maximum extent of the 
near-field), we calculated D based on an assumed frequency of 1 kHz. A 
frequency of 1 kHz is commonly used in near-field/far-field 
calculations for airgun arrays (Zykov and Carr, 2014; MacGillivray, 
2006; NSF and USGS, 2011), and based on representative airgun spectrum 
data and field measurements of an airgun array used on the Langseth, 
nearly all (greater than 95 percent) of the energy from airgun arrays 
is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz as the upper 
cut-off for calculating the maximum extent of the near-field should 
reasonably represent the near-field extent in field conditions.
    If the largest distance to the peak sound pressure level threshold 
was equal to or less than the longest dimension of the array (i.e., 
under the array), or within the near-field, then received levels that 
meet or exceed the threshold in most cases are not expected to occur. 
This is because within the near-field and within the dimensions of the 
array, the source levels specified in Table 5 are overestimated and not 
applicable. In fact, until one reaches a distance of approximately 
three or four times the near-field distance the average intensity of 
sound at any given distance from the array is still less than that 
based on calculations that assume a directional point source (Lurton, 
2002). The 6,600-in\3\ airgun array used in the proposed survey has an 
approximate

[[Page 19615]]

diagonal of 28.8 m, resulting in a near-field distance of 138.7 m at 1 
kHz (NSF and USGS, 2011). Field measurements of this array indicate 
that the source behaves like multiple discrete sources, rather than a 
directional point source, beginning at approximately 400 m (deep site) 
to 1 km (shallow site) from the center of the array (Tolstoy et al., 
2009), distances that are actually greater than four times the 
calculated 140-m near-field distance. Within these distances, the 
recorded received levels were always lower than would be predicted 
based on calculations that assume a directional point source, and 
increasingly so as one moves closer towards the array (Tolstoy et al., 
2009). Given this, relying on the calculated distance (138.7 m) as the 
distance at which we expect to be in the near-field is a conservative 
approach since even beyond this distance the acoustic modeling still 
overestimates the actual received level. Within the near-field, in 
order to explicitly evaluate the likelihood of exceeding any particular 
acoustic threshold, one would need to consider the exact position of 
the animal, its relationship to individual array elements, and how the 
individual acoustic sources propagate and their acoustic fields 
interact. Given that within the near-field and dimensions of the array 
source levels would be below those in Table 5, we believe exceedance of 
the peak pressure threshold would only be possible under highly 
unlikely circumstances.
    In consideration of the received sound levels in the near-field as 
described above, we expect the potential for Level A harassment of mid-
frequency cetaceans, otariid pinnipeds, and phocid pinnipeds to be de 
minimis, even before the likely moderating effects of aversion and/or 
other compensatory behaviors (e.g., Nachtigall et al., 2018) are 
considered. We do not believe that Level A harassment is a likely 
outcome for any mid-frequency cetacean, otariid pinniped, or phocid 
pinniped and do not propose to authorize any Level A harassment for 
these species.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, and group dynamics of marine mammals that will inform the take 
calculations.
    Extensive systematic aircraft- and ship-based surveys have been 
conducted for marine mammals in offshore waters of Oregon and 
Washington (e.g., Bonnell et al., 1992; Green et al., 1992, 1993; 
Barlow 1997, 2003; Barlow and Taylor 2001; Calambokidis and Barlow 
2004; Barlow and Forney 2007; Forney 2007; Barlow 2010). Ship surveys 
for cetaceans in slope and offshore waters of Oregon and Washington 
were conducted by NMFS' Southwest Fisheries Science Center (SWFSC) in 
1991, 1993, 1996, 2001, 2005, 2008, and 2014 and synthesized by Barlow 
(2016); these surveys were conducted from the coastline up to ~556 km 
from shore from June or August to November or December. These data were 
used by the SWFSC to develop spatial models of cetacean densities for 
the California Current Ecosystem (CCE). Systematic, offshore, at-sea 
survey data for pinnipeds are more limited (e.g., Bonnell et al., 1992; 
Adams et al., 2014); In British Columbia, several systematic surveys 
have been conducted in coastal waters (e.g., Williams and Thomas 2007; 
Ford et al., 2010a; Best et al., 2015; Harvey et al., 2017). Surveys in 
coastal as well as offshore waters were conducted by DFO during 2002 to 
2008; however, little effort occurred off the west coast of Vancouver 
Island during late spring/summer (Ford et al., 2010). Density estimates 
for the proposed survey areas outside the U.S. EEZ, i.e., in the 
Canadian EEZ, were not readily available, so density estimates for U.S. 
waters were applied to the entire survey area.
    The U.S. Navy primarily used SWFSC habitat-based cetacean density 
models to develop a marine species density database (MSDD) for the 
Northwest Training and Testing (NWTT) Study Area for NWTT Phase III 
activities (U.S. Navy 2019a), which encompasses the U.S. portion of the 
proposed survey area. For several cetacean species, the Navy updated 
densities estimated by line-transect surveys or mark-recapture studies 
(e.g., Barlow 2016). These methods usually produce a single value for 
density that is an averaged estimate across very large geographical 
areas, such as waters within the U.S. EEZ off California, Oregon, and 
Washington (referred to as a ``uniform'' density estimate). This is the 
general approach applied in estimating cetacean abundance in the NMFS 
stock assessment reports. The disadvantage of these methods is that 
they do not provide spatially- or temporally-explicit density 
information. More recently, a newer method called spatial habitat 
modeling has been used to estimate cetacean densities that address some 
of these shortcomings (e.g., Barlow et al., 2009; Becker et al., 2010; 
2012a; 2014; Becker et al., 2016; Ferguson et al., 2006; Forney et al., 
2012; 2015; Redfern et al., 2006). (Note that spatial habitat models 
are also referred to as ``species distribution models'' or ``habitat-
based density models.'') These models estimate density as a continuous 
function of habitat variables (e.g., sea surface temperature, seafloor 
depth) and thus, within the study area that was modeled, densities can 
be predicted at all locations where these habitat variables can be 
measured or estimated. Spatial habitat models therefore allow estimates 
of cetacean densities on finer scales (spatially and temporally) than 
traditional line-transect or mark-recapture analyses.
    The methods used to estimate pinniped at-sea densities are 
typically different than those used for cetaceans, because pinnipeds 
are not limited to the water and spend a significant amount of time on 
land (e.g., at rookeries). Pinniped abundance is generally estimated 
via shore counts of animals on land at known haulout sites or by 
counting number of pups weaned at rookeries and applying a correction 
factor to estimate the abundance of the population (for example Harvey 
et al., 1990; Jeffries et al., 2003; Lowry, 2002; Sepulveda et al., 
2009). Estimating in[hyphen]water densities from land-based counts is 
difficult given the variability in foraging ranges, migration, and 
haulout behavior between species and within each species, and is driven 
by factors such as age class, sex class, breeding cycles, and seasonal 
variation. Data such as age class, sex class, and seasonal variation 
are often used in conjunction with abundance estimates from known 
haulout sites to assign an in-water abundance estimate for a given 
area. The total abundance divided by the area of the region provides a 
representative in-water density estimate for each species in a 
different location. In addition to using shore counts to estimate 
pinniped density, traditional line-transect derived estimates are also 
used, particularly in open ocean areas.
    The Navy's MSDD is currently the most comprehensive compendium for 
density data available for the CCE. However, data products are 
currently not publically available for the database; thus, in this 
analysis the Navy's data products were used only for species for which 
density data were not available from an alternative spatially-explicit 
model (e.g., pinnipeds, Kogia spp., minke whales, sei whales, gray 
whales, short-finned pilot whales, and Northern Resident, transient, 
and offshore killer whales). For these species, GIS was used to 
determine the areas expected to be ensonified in each density category 
(i.e., distance from shore). For pinnipeds, the densities from the 
Navy's MSDD were corrected by projecting the most recent population 
growth and updated population estimates to 2020, when

[[Page 19616]]

available. Where available, the appropriate seasonal density estimate 
from the MSDD was used in the estimation here (i.e., summer).
    NMFS obtained data products from the Navy for densities of Southern 
Resident killer whales in the NWTT Offshore Study Area. The modeled 
density estimates were available on the scale of 1 km by 1 km grid 
cells. The densities from grid cells overlapping the ensonified area in 
each depth category were multiplied by the corresponding area to 
estimate potential exposures (Table 9).
    For most other species, (i.e., humpback, blue, fin, sperm, Baird's 
beaked, and other small beaked whales; bottlenose, striped, common, 
Pacific white-sided, Risso's and northern right whale dolphins; and 
Dall's porpoise), habitat-based density models from Becker et al. 
(2016) were used. Becker et al. (2016) used seven years of SWFSC 
cetacean line-transect survey data collected between 1991 and 2009 to 
develop predictive habitat-based models of cetacean densities in the 
CCE. The modeled density estimates were available on the scale of 7 km 
by 10 km grid cells. The densities from all grid cells overlapping the 
ensonified areas within each water depth category were averaged to 
calculate a zone-specific density for each species.
    Becker et al. (2016) did not develop a density model for the harbor 
porpoise, so densities from Forney et al. (2014) were used for that 
species. Forney et al. (2014) presented estimates of harbor porpoise 
abundance and density along the Pacific coast of California, Oregon, 
and Washington based on aerial line-transect surveys conducted between 
2007 and 2012. Separate density estimates were provided for harbor 
porpoises in Oregon south of 45[deg] N and Oregon/Washington north of 
45[deg] N (i.e., within the boundaries of the Northern California/
Southern Oregon and Northern Oregon/Washington Coast stocks), so stock-
specific take estimates were generated (Forney et al., 2014).
    Background information on the density calculations for each 
species/guild (if different from the general methods from the Navy's 
MSDD, Becker et al. (2016), or Forney et al. (2014) described above) 
are reported here. Density estimates for each species/guild (aside from 
Southern Resident killer whales, which are discussed separately) are 
found in Table 7.
Gray Whale
    DeAngelis et al. (2011) developed a migration model that provides 
monthly, spatially explicit predictions of gray whale abundance along 
the U.S. West Coast from December through June. These monthly density 
estimates apply to a ``main migration corridor'' that extends from the 
coast to 10 km offshore. A zone from the main migration corridor out to 
47 km offshore is designated as an area of ``potential presence''. To 
derive a density estimate for this area the Navy assumed that 1 percent 
of the population could be within the 47-km ``potential presence'' area 
during migration. Given the 2014 stock assessment population estimate 
of 20,990 animals (Carretta et al., 2017b), approximately 210 gray 
whales may use this corridor. Assuming the migration wave lasts 30 
days, then 7 whales on average on any one day could occur in the 
``potential presence'' area. The area from the main migration route 
offshore to 47 km within the NWTT study area = 45,722.06 km\2\, so 
density within this zone = 0.00015 whales/km\2\. From July-November, 
gray whale occurrence off the coast is expected to consist primarily of 
whales belonging to the PCFG. Calambokidis et al. (2012) provided an 
updated analysis of the abundance of the PCFG whales in the Pacific 
Northwest and recognized that this group forms a distinct feeding 
aggregation. For the purposes of establishing density, the Navy assumed 
that from July 1 to November 30 all the 209 PCFG whales could be 
present off the coast in the Northern California/Oregon/Washington 
region (this accounts for the potential that some PCFG whales may be 
outside of the area but that there also may be some non-PCFG whales in 
the region as noted by Calambokidis et al.(2012)). Given that the PCFG 
whales are found largely nearshore, it was assumed that all the whales 
could be within 10 km of the coast. To capture the potential presence 
of whales further offshore (e.g., Oleson et al., 2009), it was assumed 
that a percentage of the whales could be present from 10 km out to 47 
km off the coast; the 47 km outer limit is consistent with the 
DeAngelis et al. (2011) migration model. Since 77 percent of the PCFG 
sightings were within the nearshore BIAs (Calambokidis et al., 2015), 
it was assumed that 23 percent (48 whales) could potentially be found 
further offshore. Two strata were thus developed for the July-November 
gray whale density layers: (1) From the coast to 10 km offshore, and 
(2) from 10 km to 47 km offshore. The density was assumed to be 0 
animals/km\2\ for areas offshore of 47 km.
Small Beaked Whale Guild
    NMFS has developed habitat-based density models for a small beaked 
whale guild in the CCE (Becker et al., 2012b; Forney et al., 2012). The 
small beaked whale guild includes Cuvier's beaked whale and beaked 
whales of the genus Mesoplodon, including Blainville's beaked whale, 
Hubbs' beaked whale, and Stejneger's beaked whale. NMFS SWFSC developed 
a CCE habitat-based density model for the small beaked whale guild 
which provides spatially explicit density estimates off the U.S. West 
Coast for summer and fall based on survey data collected between 1991 
and 2009 (Becker et al., 2016).
False Killer Whale
    False killer whales were not included in the Navy's MSDD, as they 
are very rarely encountered in the northeast Pacific. Density estimates 
for false killer whales were also not presented in Barlow (2016) or 
Becker et al. (2016), as no sightings occurred during surveys conducted 
between 1986 and 2008 (Ferguson and Barlow 2001, 2003; Forney 2007; 
Barlow 2003, 2010). One sighting was made off of southern California 
during 2014 (Barlow 2016). One pod of false killer whales occurred in 
Puget Sound for several months during the 1990s (Navy 2015). Based on 
the available information, NMFS does not believe false killer whales 
are expected to be taken, but L-DEO has requested take of this species 
so we are proposing to authorize take.
Killer Whale
    A combination of movement data (from both visual observations and 
satellite-linked tags) and detections from stationary acoustic 
recorders have provided information on the offshore distribution of the 
Southern Resident stock (Hanson et al., 2018). These data have been 
used to develop state space movement models that provide estimates of 
the probability of occurrence (or relative density) of Southern 
Residents in the offshore study area in winter and spring (Hanson et 
al., 2018). Since the total number of animals that comprise each pod is 
known, the relative density estimates were used in association with the 
total abundance estimates to derive absolute density estimates (i.e., 
number of animals/km\2\) within the offshore study area. Given that the 
K and L pods were together during all but one of the satellite tag 
deployments, Hanson et al. (2018) developed two separate state space 
models, one for the combined K and L pods and one for the J pod. The 
absolute density estimates were thus derived based on a total of 53 
animals for the K and L pods (K pod = 18 animals, L pod = 35 animals) 
and 22 animals for the J pod (Center for Whale Research, 2019). Of the 
three pods, the

[[Page 19617]]

K and L pods appear to have a more extensive and seasonally variable 
offshore coastal distribution, with rare sightings as far south as 
Monterey Bay, California (Carretta et al., 2019; Ford et al., 2000; 
Hanson et al., 2018). Two seasonal density maps were thus developed for 
the K and L pods, one representing their distribution from January to 
May (the duration of the tag deployments), and another representing 
their distribution from June to December. Based on stationary acoustic 
recording data, their excursions offshore from June to December are 
more limited and typically do not extend south of the Columbia River 
(Emmons 2019). To provide more conservative density estimates, the Navy 
extended the June to December distribution to just south of the 
Columbia River and redistributed the total K and L populations (53 
animals) within the more limited range boundaries. A conservative 
approach was also adopted for the J pod since the January to May 
density estimates were assumed to represent annual occurrence patterns, 
despite information that this pod typically spends more time in the 
inland waters during the summer and fall (Carretta et al., 2019; Ford 
et al., 2000; Hanson et al., 2018). Further, for all seasons the Navy 
assumed that all members of the three pods of Southern Residents could 
occur either offshore or in the inland waters, so the total number of 
animals in the stock was used to derive density estimates for both 
study areas.
    Due to the difficulties associated with reliably distinguishing the 
different stocks of killer whales from at sea sightings, and 
anticipated equal likelihood of occurrence among the stocks, density 
estimates for the rest of the stocks are presented as a whole (i.e., 
includes the Offshore, West Coast Transient, and Northern Resident 
stocks). Barlow (2016) presents density values for killer whales in the 
CCE, with separate densities for waters off Oregon/Washington (i.e., 
north of the California border) and Northern California for summer/
fall. Density data are not available for the NWTT Offshore area 
northwest of the CCE study area, so data from the SWFSC Oregon/
Washington area were used as representative estimates. These values 
were used to represent density year-round.
Short-Finned Pilot Whale
    Along the U.S. West Coast, short-finned pilot whales were once 
common south of Point Conception, California (Carretta et al., 2017b; 
Reilly & Shane, 1986), but now sightings off the U.S. West Coast are 
infrequent and typically occur during warm water years (Carretta et 
al., 2017b). Stranding records for this species from Oregon and 
Washington waters are considered to be beyond the normal range of this 
species rather than an extension of its range (Norman et al., 2004). 
Density values for short-finned pilot whales are available for the 
SWFSC Oregon/Washington and Northern California strata for summer/fall 
(Barlow, 2016). Density data are not available for the NWTT Offshore 
area northwest of the SWFSC strata, so data from the SWFSC Oregon/
Washington stratum were used as representative estimates. These values 
were used to represent density year-round.
Guadalupe Fur Seal
    Adult male Guadalupe fur seals are expected to be ashore at 
breeding areas over the summer, and are not expected to be present 
during the planned geophysical survey (Caretta et al., 2017b; Norris 
2017b). Additionally, breeding females are unlikely to be present 
within the Offshore Study Area as they remain ashore to nurse their 
pups through the fall and winter, making only short foraging trips from 
rookeries (Gallo-Reynoso et al., 2008; Norris 2017b; Yochem et al., 
1987). To estimate the total abundance of Guadalupe fur seals, the Navy 
adjusted the population reported in the 2016 SAR (Caretta et al., 
2017b) of 20,000 seals by applying the average annual growth rate of 
7.64 percent over the seven years between 2010 and 2017. The resulting 
2017 projected abundance was 33,485 fur seals. Using the reported 
composition of the breeding population of Guadalupe fur seals (Gallo-
Reynoso 1994) and satellite telemetry data (Norris 2017b), the Navy 
established seasonal and demographic abundances of Guadalupe fur seals 
expected to occur within the Offshore Study Area.
    The distribution of Guadalupe fur seals in the Offshore Study Area 
was stratified by distance from shore (or water depth) to reflect their 
preferred pelagic habitat (Norris, 2017a). Ten percent of fur seals in 
the Study Area are expected to use waters over the continental shelf 
(approximated as waters with depths between 10 and 200 m). A depth of 
10 m is used as the shoreward extent of the shelf (rather than 
extending to shore), because Guadalupe fur seals in the Offshore Study 
Area are not expected to haul out and would not be likely to come close 
to shore. All fur seals (i.e., 100 percent) would use waters off the 
shelf (beyond the 200-m isobath) out to 300 km from shore, and 25 of 
percent of fur seals would be expected to use waters between 300 and 
700 km from shore (including the planned geophysical survey area). The 
second stratum (200 m to 300 km from shore) is the preferred habitat 
where Guadalupe fur seals are most likely to occur most of the time. 
Individuals may spend a portion of their time over the continental 
shelf or farther than 300 km from shore, necessitating a density 
estimate for those areas, but all Guadalupe fur seals would be expected 
to be in the central stratum most of the time, which is the reason 100 
percent is used in the density estimate for the central stratum 
(Norris, 2017a). Spatial areas for the three strata were estimated in a 
GIS and used to calculate the densities.
    The Navy's density estimate for Guadalupe fur seals projected the 
abundance through 2017, while L-DEO's survey will occur in 2020. 
Therefore, we have projected the abundance estimate in 2020 using the 
abundance estimate (34,187 animals) and population growth rate (5.9 
percent) presented in the 2019 draft SARs (Caretta et al., 2019). This 
calculation yielded an increased density estimate of Guadalupe fur 
seals than what was presented in the Navy's MSDD.
Northern Fur Seal
    The Navy estimated the abundance of northern fur seals from the 
Eastern Pacific stock and the California breeding stock that could 
occur in the NWTT Offshore Study Area by determining the percentage of 
time tagged animals spent within the Study Area and applying that 
percentage to the population to calculate an abundance for adult 
females, juveniles, and pups independently on a monthly basis. Adult 
males are not expected to occur within the Offshore Study Area and the 
planned survey area during the planned geophysical survey as they spend 
the summer ashore at breeding areas in the Bering Sea and San Miguel 
Island (Caretta et al., 2017b). Using the monthly abundances of fur 
seals within the Offshore Study Area, the Navy created strata to 
estimate the density of fur seals within three strata: 22 km to 70 km 
from shore, 70 km to 130 km from shore, and 130 km to 463 km from shore 
(the western Study Area boundary). L-DEO's planned survey is 423 km 
from shore at the closest point. Based on satellite tag data and 
historic sealing records (Olesiuk 2012; Kajimura 1984), the Navy 
assumed 25 percent of the population present within the overall 
Offshore Study Area may be within the 130 km to 463 km stratum.
    The Navy's density estimates for northern fur seals did not include 
the latest abundance data collected from Bogoslof Island or the 
Pribilof Islands in 2015 and 2016. Incorporating the latest

[[Page 19618]]

pup counts yielded a slight decrease in the population abundance 
estimate, which resulted in a slight decrease in the estimated 
densities of northern fur seals in each depth stratum.
Steller Sea Lion
    The Eastern stock of Steller sea lions has established rookeries 
and breeding sites along the coasts of California, Oregon, British 
Columbia, and southeast Alaska. A new rookery was recently discovered 
along the coast of Washington at the Carroll Island and Sea Lion Rock 
complete, where more than 100 pups were born in 2015 (Muto et al., 
2017; Wiles 2015). The 2017 SAR did not factor in pups born at sites 
along the Washington coast (Muto et al., 2017). Considering that pups 
have been observed at multiple breeding sites since 2013, specifically 
at the Carroll Island and Sea Lion Rock complex (Wiles 2015), the 2017 
SAR abundance of 1,407 Steller sea lions (non-pups only) for Washington 
underestimates the total population. Wiles (2015) estimates that up to 
2,500 Steller sea lions are present along the Washington coast, which 
is the abundance estimate used by the Navy to calculate densities. 
Approximately 30,000 Steller sea lions occur along the coast of British 
Columbia, but these animals were not included in the Navy's 
calculations. The Navy applied the annual growth rate for each regional 
population (California, Oregon, Washington, and southeast Alaska), 
reported in Muto et al. (2017), to each population to estimate the 
stock abundance in 2017, and we further projected the population 
estimate in 2020.
    Sea lions from northern California and southern Oregon rookeries 
migrate north in September following the breeding season and winter in 
northern Oregon, Washington, and British Columbia waters. They disperse 
widely following the breeding season, which extends from May through 
July, likely in search of different types of prey, which may be 
concentrated in areas where oceanic fronts and eddies persist (Fritz et 
al., 2016; Jemison et al., 2013; Lander et al., 2010; Muto et al., 
2017; NMFS 2013; Raum-Suryan et al., 2004; Sigler et al., 2017). Adults 
depart rookeries in August. Females with pups remain within 500 km of 
their rookery during the non-breeding season and juveniles of both 
sexes and adult males disperse more widely but remain primarily over 
the continental shelf (Wiles 2015).
    Based on 11 sightings along the Washington coast, Steller sea lions 
were observed at an average distance of 13 km from shore and 35 km from 
the shelf break (defined as the 200-m isobath) (Oleson et al., 2009). 
The mean water depth in the area of occurrence was 42 m, and surveys 
were conducted out to approximately 60 km from shore. Wiles (2015) 
estimated that Steller sea lions off the Washington coast primarily 
occurred within 60 km of shore, favoring habitats over the continental 
shelf. However, a few individuals may travel several hundred km 
offshore (Merrick & Loughlin 1997; Wiles 2015). Based on these 
occurrence and distribution data, two strata were used to estimate 
densities for Steller sea lions. The spatial area extending from shore 
to the 200-m isobath (i.e., over the continental shelf) was defined as 
one stratum, and the second stratum extended from the 200-m isobath to 
300 km from shore to account for reports of Steller sea lions occurring 
several hundred km offshore. Ninety-five percent of the population of 
Steller sea lions occurring in the NWTT Study Area were distributed 
over the continental shelf stratum and the remaining five percent were 
assumed to occur between the 200-m isobath and 300 km from shore.
    The percentage of time Steller sea lions spend hauled out varies by 
season, life stage, and geographic location. To calculated densities in 
the Study Area, the projected population abundance was adjusted to 
account for time spent hauled out. In spring and winter, sea lions were 
estimated to be in the water 64 percent of the time. In summer, when 
sea lions are more likely to be in the water, the percent of animals 
estimated to be in the water was increased to 76 percent, and in fall, 
sea lions were anticipated to be in the water 53 percent of the time 
(U.S. Navy 2019). Densities were calculated for each depth stratum off 
Washington and off Oregon.
California Sea Lion
    Seasonal at-sea abundance of California sea lions is estimated from 
strip transect survey data collected offshore along the California 
coastline (Lowry & Forney 2005). The survey area was divided into seven 
strata, labeled A through G. Abundance estimates from the two 
northernmost strata (A and B) were used to estimate the abundance of 
California sea lions occurring in the NWTT Study Area. While the 
northernmost stratum (A) only partially overlaps with the Study Area, 
this approach conservatively assumes that all sea lions from the two 
strata would continue north into the Study Area.
    The majority of male sea lions would be expected in the NWTT Study 
Area from August to mid-June (Wright et al., 2010). In summer, males 
are expected to be at breeding sites off of Southern California. In-
water abundance estimates of adult and sub-adult males in strata A and 
B were extrapolated to estimate seasonal densities in the Study Area. 
Approximately 3,000 male California sea lions are known to pass through 
the NWTT Study Area in August as they migrate northward to the 
Washington coast and inland waters (DeLong 2018a; Wright et al., 2010). 
Nearly all male sea lions are expected to be on or near breeding sites 
off California in July (DeLong et al., 2017; Wright et al., 2010). An 
estimate of 3,000 male sea lions is used for the month of August. 
Projected 2017 seasonal abundance estimates were derived by applying an 
annual growth rate of 5.4 percent (Caretta et al., 2017b) between 1999 
and 2017 to the abundance estimates from Lowry & Forney (2005).
    The strata used to calculated densities in the NWTT Study Area were 
based on distribution data from Wright et al. (2010) and Lowry & Forney 
(2005) indicating that approximately 90 percent of California sea lions 
occurred within 40 km of shore and 100 percent of sea lions were within 
70 km of shore. A third stratum was added that extends from shore to 
450 km offshore to account for anomalous conditions, such as changes in 
sea surface temperature and upwelling associated with El Ni[ntilde]o, 
during which California sea lions have been encountered farther from 
shore, presumably seeking prey (DeLong & Jeffries 2017; Weise et al., 
2010). The Navy calculated densities for each stratum (0 to 40 km, 40 
to 70 km, and 0 to 450 km) for each season, spring, summer, fall, and 
winter, but noted that the density of California sea lions in all 
strata for June and July was 0 animals/km\2\. The Navy's calculated 
densities for August were conservatively used here, as sightings of 
California sea lions have been reported on the continental shelf in 
June and July (Adams et al., 2014).
Northern Elephant Seal
    The most recent surveys supporting the abundance estimate for 
northern elephant seals were conducted in 2010 (Caretta et al., 2017b). 
By applying the average growth rate of 3.8 percent per year for the 
California breeding stock over the seven years from 2010 to 2017, the 
Navy calculated a projected 2017 abundance estimate of 232,399 elephant 
seals (Caretta et al., 2017b; Lowry et al., 2014). Male and female 
distributions at sea differ both seasonally and spatially. Pup counts 
reported by Lowry et al., (2014) and life tables compiled by Condit et 
al., (2014) were used to determine the proportion of males and females 
in the population, which was

[[Page 19619]]

estimated to be 56 percent female and 44 percent male. Females are 
assumed to be at sea 100 percent of the time within their seasonal 
distribution area in fall and summer (Robinson et al., 2012). Males are 
at sea approximately 90 percent of the time in fall and spring, remain 
ashore through the entire winter, and spend one month ashore to molt in 
the summer (i.e., are at sea 66 percent of the summer). Monthly 
distribution maps produced by Robinson et al. (2012) showing the extent 
of foraging areas used by satellite tagged female elephant seals were 
used to estimate the spatial areas to calculate densities. Although the 
distributions were based on tagged female seals, Le Boeuf et al. (2000) 
and Simmons et al. (2007) reported similar tracks by males over broad 
spatial scales. The spatial areas representing each monthly 
distribution were calculating using GIS and then averaged to produce 
seasonally variable areas and resulting densities.
    As with other pinniped species above, NMFS used the population 
growth rate reported by Caretta et al. (2017b) to project the estimated 
abundance in 2020. The resulting population estimate and estimated 
densities increased from those presented in the Navy's MSDD (U.S. Navy 
2019).
Harbor Seal
    Only harbor seals from the Washington and Oregon Coast stock would 
be expected to occur in the proposed survey area. The most recent 
abundance estimate for the Washington and Oregon Coast stock is 24,732 
harbor seals (Caretta et al., 2017b). Survey data supporting this 
abundance estimate are from 1999, which exceeds the eight-year limit 
beyond which NMFS will not confirm abundance in a SAR (Caretta et al., 
2017b). However, based on logistical growth curves for the Washington 
and Oregon Coast stock that leveled off in the early 1990s (Caretta et 
al., 2017b) and unpublished data from the Washington Department of Fish 
and Wildlife (DeLong & Jeffries 2017), an annual growth rate of 0 
percent (i.e., the population has remained stable) was applied such 
that the 2017 abundance estimate used by the Navy, and 2020 estimate 
used here, was still 24,732 harbor seals. A haulout factor of 33 
percent was used to account for hauled-out seals (i.e., seals are 
estimated to be in the water 33 percent of the time) (Huber et al., 
2001). A single stratum extending from shore to 30 km offshore was used 
to define the spatial area used by the Navy for calculating densities 
off Washington and Oregon (Bailey et al., 2014; Oleson et al., 2009).

Marine Mammal Densities

    Densities for most species are presented by depth stratum (shallow, 
intermediate, and deep water) in Table 7. For species where densities 
are available based on other categories (gray whale, harbor porpoise, 
northern fur seal, Guadalupe fur seal, California sea lion, Steller sea 
lion), category definitions are provided in the footnotes of Table 7.

                            Table 7--Marine Mammal Density Values in the Survey Area
----------------------------------------------------------------------------------------------------------------
                                                  Estimated density (#/km\2\)
                                       ------------------------------------------------
                Species                                  Intermediate                           Reference
                                        Shallow <100 m/   100-1000 m/    Deep >1000 m/
                                          category 1      category 2      category 3
----------------------------------------------------------------------------------------------------------------
LF Cetaceans:
    Humpback whale....................       0.0052405       0.0040200       0.0004830  Becker et al. (2016).
    Blue whale........................       0.0020235       0.0010518       0.0003576  Becker et al. (2016).
    Fin whale.........................       0.0002016       0.0009306       0.0013810  Becker et al. (2016).
    Sei whale.........................       0.0004000       0.0004000       0.0004000  U.S. Navy (2019).
    Minke whale.......................       0.0013000       0.0013000       0.0013000  U.S. Navy (2019).
    Gray whale \a\....................       0.0155000       0.0010000            N.A.  U.S. Navy (2019).
MF Cetaceans:
    Sperm whale.......................       0.0000586       0.0001560       0.0013023  Becker et al. (2016).
    Baird's beaked whale..............       0.0001142       0.0002998       0.0014680  Becker et al. (2016).
    Small beaked whale................       0.0007878       0.0013562       0.0039516  Becker et al. (2016).
    Bottlenose dolphin................       0.0000007       0.0000011       0.0000108  Becker et al. (2016).
    Striped dolphin...................       0.0000000       0.0000025       0.0001332  Becker et al. (2016).
    Short-beaked common dolphin.......       0.0005075       0.0010287       0.0016437  Becker et al. (2016).
    Pacific white-sided dolphin.......       0.0515230       0.0948355       0.0700595  Becker et al. (2016).
    Northern right-whale dolphin......       0.0101779       0.0435350       0.0621242  Becker et al. (2016).
    Risso's dolphin...................       0.0306137       0.0308426       0.0158850  Becker et al. (2016).
    False killer whale \b\............            N.A.            N.A.            N.A.  ........................
    Killer whale (all stocks except          0.0009200       0.0009200       0.0009200  U.S. Navy (2019).
     Southern Residents).
    Short-finned pilot whale..........       0.0002500       0.0002500       0.0002500  U.S. Navy (2019).
HF Cetaceans:
    Pygmy/dwarf sperm whale...........       0.0016300       0.0016300       0.0016300  U.S. Navy (2019).
    Dall's porpoise...................       0.1450767       0.1610605       0.1131827  Becker et al. (2016).
    Harbor porpoise \c\...............       0.6240000       0.4670000            N.A.  Forney et al. (2014).
Otariids:
    Northern fur seal \d\.............       0.0113247       0.1346441       0.0103424  U.S. Navy (2019).
    Guadalupe fur seal \e\............       0.0234772       0.0262595            N.A.  U.S. Navy (2019).
    California sea lion \f\...........       0.0288000       0.0037000       0.0065000  U.S. Navy (2019).
    Steller sea lion \g\..............       0.3088864       0.0022224            N.A.  U.S. Navy (2019).
Phocids:
    Northern elephant seal............       0.0345997       0.0345997       0.0345997  U.S. Navy (2019).
    Harbor seal \h\...................       0.3424000            N.A.            N.A.  U.S. Navy (2019).
----------------------------------------------------------------------------------------------------------------
\a\ Category 1 = 0-10 km offshore, Category 2 = 10-47 km offshore (U.S. Navy 2019).
\b\ No density estimates available for false killer whales in the survey area, take is based on mean group size
  from Mobley et al. (2000).
\c\ Category 1 = South of 45[deg] N, Category 2 = North of 45[deg] N (Forney et al., 2014).
\d\ Category 1 = 22-70 km offshore, Category 2 = 70-130 km offshore, Category 3 = 130-463 km offshore (U.S. Navy
  2019).

[[Page 19620]]

 
\e\ Category 1 = 10-200 m depth, Category 2 = 200 m depth-300 km offshore; No stock-specific densities are
  available so these densities were applied to northern fur seals as a species (U.S. Navy 2019).
\f\ Category 1 = 0-40 km offshore, Category 2 = 40-70 km offshore, Category 3 = 0-450 km offshore (U.S. Navy
  2019).
\g\ Category 1 = shore-200 m depth, Category 2 = 200 m depth-300 m offshore (U.S. Navy 2019).
\h\ Category 1 = 0-30 km offshore (U.S. Navy 2019).

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. In order to estimate 
the number of marine mammals predicted to be exposed to sound levels 
that would result in Level A or Level B harassment, radial distances 
from the airgun array to predicted isopleths corresponding to the Level 
A harassment and Level B harassment thresholds are calculated, as 
described above. Those radial distances are then used to calculate the 
area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the Level A and Level B harassment thresholds. The 
distance for the 160-dB threshold (based on L-DEO model results) was 
used to draw a buffer around every transect line in GIS to determine 
the total ensonified area in each depth category (Table 8). The areas 
presented in Table 8 do not include areas ensonified within Canadian 
territorial waters (from 0-12 nmi (22.2 km) from shore). As discussed 
above, NMFS cannot authorize the incidental take of marine mammals in 
the territorial seas of foreign nations, as the MMPA does not apply in 
those waters. However, NMFS has still calculated the level of 
incidental take in the entire activity area (including Canadian 
territorial waters) as part of the analysis supporting our preliminary 
determination under the MMPA that the activity will have a negligible 
impact on the affected species. The total estimated take in U.S. and 
Canadian waters is presented in Table 11.
    In past applications, to account for unanticipated delays in 
operations, L-DEO has added 25 percent in the form of operational days, 
which is equivalent to adding 25 percent to the proposed line km to be 
surveyed. In this application, however, due to the strict operational 
timelines and availability of the R/V Langseth, no additional time or 
distance has been added to the survey calculations. 37 days is the 
absolute maximum amount of time the R/V Langseth is available to 
conduct seismic operations.
    The ensonified areas in Table 8 were used to estimate take of 
marine mammal species with densities available for the three depth 
strata (shallow, intermediate, and deep waters). For other species 
where densities are available based on other categories (i.e., gray 
whale, harbor porpoise, northern fur seal, Guadalupe fur seal, 
California sea lion, Steller sea lion; see Table 7), GIS was used to 
determine the areas expected to be ensonified in each density category 
(see Table B-2 in L-DEO's application for the ensonified areas in each 
category).

         Table 8--Areas (km\2\) Estimated to be Ensonified to Level A and Level B Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                                                                       Total
                  Survey zone                               Criteria                 Relevant       ensonified
                                                                                   isopleth  (m)   area  (km\2\)
----------------------------------------------------------------------------------------------------------------
Level B Harassment:
    Shallow <100 m............................  160 dB..........................      \a\ 12,650       11,433.80
    Intermediate 100-1000 m...................  160 dB..........................       \b\ 9,468       24,200.75
    Deep >1000 m..............................  160 dB..........................       \b\ 6,733       50,924.56
                                               -----------------------------------------------------------------
                                                                                         Overall       86,559.11
Level A Harassment
    All depth zones...........................  LF Cetacean.....................           426.9        5,605.34
                                                MF Cetacean.....................            13.6          179.85
                                                HF Cetacean.....................           268.3        3,532.92
                                                Otariid.........................            10.6          140.19
                                                Phocid..........................            43.7          577.63
----------------------------------------------------------------------------------------------------------------
\a\ Based on L-DEO model results.
\b\ Based on data from Crone et al. (2014).

    Density estimates for Southern Resident killer whales from the U.S. 
Navy's MSDD were overlaid with GIS layers of the Level B harassment 
zones in each depth category to determine the areas expected to be 
ensonified in each density category (Table 9).

   Table 9--Southern Resident Killer Whale Densities and Corresponding
                            Ensonified Areas
------------------------------------------------------------------------
                                     Density  (animals/     Ensonified
                Pod                        km\2\)          area  (km\2\)
------------------------------------------------------------------------
K/L...............................              0.000000           5,883
                                      0.000001--0.002803          17,875
                                      0.002804--0.005615           2,817
                                      0.005616--0.009366           1,200
                                      0.009367--0.015185             320
J.................................              0.000000           7,260
                                      0.000001--0.001991           8,648
                                      0.001992--0.005010           1,128

[[Page 19621]]

 
                                      0.005011--0.009602             236
                                      0.009603--0.018822              20
------------------------------------------------------------------------

    The marine mammals predicted to occur within these respective 
areas, based on estimated densities or other occurrence records, are 
assumed to be incidentally taken. For species where NMFS expects take 
by Level A harassment to potentially occur, the calculated Level A 
harassment takes have been subtracted from the total within the Level B 
harassment zone. Estimated exposures for the proposed survey outside of 
Canadian territorial waters are shown in Table 10.

                               Table 10--Estimated Taking by Level A and Level B Harassment, and Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Estimated take
                  Species                          MMPA stock \a\              Stock     --------------------------------      Total        Percent of
                                                                             abundance        Level B         Level A     proposed  take    MMPA stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
LF Cetaceans:
    Humpback whale........................  Central North Pacific.......          10,103             172              10         \b\ 182            1.80
                                            California/Oregon/Washington           2,900                                                            6.28
    Blue whale............................  Eastern North Pacific.......           1,647              63               4              67            4.06
    Fin whale.............................  California/Oregon/Washington           9,029              89               6              95            1.06
                                            Northeast Pacific...........           3,168                                                            3.01
    Sei whale.............................  Eastern North Pacific.......          27,197              32               2              34            0.13
    Minke whale...........................  California/Oregon/Washington          25,000             105               7             112            0.45
    Gray whale............................  Eastern North Pacific.......          26,960              90               2              92            0.34
MF Cetaceans:
    Sperm whale...........................  California/Oregon/Washington          26,300              71               0              71            0.27
    Baird's beaked whale..................  California/Oregon/Washington           2,697              83               0              83            3.08
    Small beaked whale....................  California/Oregon/Washington           6,318             244               0         \c\ 244            3.86
    Bottlenose dolphin....................  California/Oregon/Washington           1,924               1               0          \d\ 13            0.68
                                             (offshore).
    Striped dolphin.......................  California/Oregon/Washington          29,211               7               0          \d\ 46            0.16
    Short-beaked common dolphin...........  California/Oregon/Washington         969,861             114               0         \d\ 179            0.02
    Pacific white-sided dolphin...........  California/Oregon/Washington          26,814           6,452               0           6,452           24.06
    Northern right-whale dolphin..........  California/Oregon/Washington          26,556           4,333               0           4,333           16.32
    Risso's dolphin.......................  California/Oregon/Washington           6,336           1,906               0           1,906           30.08
    False killer whale....................  N.A.........................            N.A.            N.A.            N.A.           \e\ 5            N.A.
    Killer whale..........................  Southern Resident...........              75              43               0              43       \g\ 57.33
                                            Northern Resident...........             302              27               0          \f\ 27            8.94
                                            West Coast Transient........             243              26                          \f\ 26           10.70
                                            Offshore....................             300              26                          \f\ 26            8.67
    Short-finned pilot whale..............  California/Oregon/Washington             836              24               0          \d\ 29            3.47
HF Cetaceans:
    Pygmy/dwarf sperm whale...............  California/Oregon/Washington           4,111             135               6             141            3.42
    Dall's porpoise.......................  California/Oregon/Washington          27,750          10,869             452          11,321       \g\ 40.80
    Harbor porpoise.......................  Northern Oregon/Washington            21,487          12,557             449          13,006       \g\ 60.53
                                             Coast.
                                            Northern California/Southern          35,769                                                       \g\ 36.36
                                             Oregon.
Otariid Seals:
    Northern fur seal.....................  Eastern Pacific.............         620,660           4,604               0           4,604            0.74
                                            California..................          14,050                                                           32.77
    Guadalupe fur seal....................  Mexico to California........          34,187           2,387               0           2,387            6.98
    California sea lion...................  U.S.........................         257,606            1140               0           1,140            0.44
    Steller sea lion......................  Eastern U.S.................          43,201            7281               0           7,281           16.85

[[Page 19622]]

 
Phocid Seals:
    Northern elephant seal................  California Breeding.........         179,000            1995               0           1,995            1.11
    Harbor seal...........................  Oregon/Washington Coast.....      \h\ 24,732            6537               0           6,537           26.43
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ In most cases, where multiple stocks are being affected, for the purposes of calculating the percentage of the stock impacted, the take is being
  analyzed as if all proposed takes occurred within each stock.
\b\ Takes are allocated among the three DPSs in the area based on Wade et al. (2017) (Oregon: 32.7% Mexico DPS, 67.2% Central America DPS; Washington/
  British Columbia: 27.9% Mexico DPS, 8.7% Central America DPS, 63.5% Hawaii DPS).
\c\ Total for small beaked whale guild. Requested take includes 7 Blainville's beaked whales, 86 Stejneger's beaked whales, 86 Cuvier's beaked whales,
  and 74 Hubbs' beaked whales (see Appendix B of L-DEO's application for more information).
\d\ Proposed take increased to mean group size from Barlow (2016).
\e\ Proposed take increased to mean group size from Mobley et al. (2000).
\f\ Total estimated take is 86 killer whales. Approximately one-third of calculated takes were assigned to each stock due to expected equal likelihood
  of occurrence in the survey area.
\g\ The percentage of these stocks expected to experience take is discussed further in the Small Numbers section later in the document.
\h\ As noted in Table 1, there is no current estimate of abundance available for the Oregon/Washington Coast stock of harbor seal. The abundance
  estimate from 1999, included here, is the best available.

    The proposed take numbers shown in Table 10 are expected to be 
conservative. Marine mammals would be expected to move away from a loud 
sound source that represents an aversive stimulus, such as an airgun 
array, potentially reducing the number of takes by Level A harassment. 
However, the extent to which marine mammals would move away from the 
sound source is difficult to quantify and is therefore not accounted 
for in the take estimates. Also, note that in consideration of the 
near-field soundscape of the airgun array, we propose to authorize a 
different number of takes of mid-frequency cetaceans and pinnipeds by 
Level A harassment than the number proposed by L-DEO (see Appendix B in 
L-DEO's IHA application).

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) the practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    L-DEO has reviewed mitigation measures employed during seismic 
research surveys authorized by NMFS under previous incidental 
harassment authorizations, as well as recommended best practices in 
Richardson et al. (1995), Pierson et al. (1998), Weir and Dolman 
(2007), Nowacek et al. (2013), Wright (2014), and Wright and Cosentino 
(2015), and has incorporated a suite of proposed mitigation measures 
into their project description based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, L-DEO has proposed to implement 
mitigation measures for marine mammals. Mitigation measures that would 
be adopted during the planned surveys include (1) Vessel-based visual 
mitigation monitoring; (2) Vessel-based passive acoustic monitoring; 
(3) Establishment of an exclusion zone; (4) Shutdown procedures; (5) 
Ramp-up procedures; and (6) Vessel strike avoidance measures.

Vessel-Based Visual Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual PSOs) to scan the ocean surface visually for the 
presence of marine mammals. The area to be scanned visually includes 
primarily the exclusion zone, 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-clearance monitoring (i.e., before ramp-up 
begins), the buffer zone also acts as an extension of the exclusion 
zone in that observations of marine mammals within the buffer zone 
would also prevent airgun operations from beginning (i.e. ramp-up). The 
buffer zone encompasses the area at and below the sea surface from the 
edge of the 0-500 m exclusion zone, out to a radius of 1,000 m from the 
edges of the airgun array (500-1,000 m). Visual monitoring of the 
exclusion 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.

[[Page 19623]]

Visual monitoring of the buffer zone is intended to (1) provide 
additional protection to na[iuml]ve marine mammals that may be in the 
area during pre-clearance, and (2) during airgun use, aid in 
establishing and maintaining the exclusion zone by alerting the visual 
observer and crew of marine mammals that are outside of, but may 
approach and enter, the exclusion zone.
    L-DEO must use dedicated, trained, NMFS-approved Protected Species 
Observers (PSOs). The PSOs must have no tasks other than to conduct 
observational effort, record observational data, and communicate with 
and instruct relevant vessel crew with regard to the presence of marine 
mammals and mitigation requirements. PSO resumes shall be provided to 
NMFS for approval.
    At least one of the visual and two of the acoustic PSOs (discussed 
below) aboard the vessel must have a minimum of 90 days at-sea 
experience working in those roles, respectively, during a deep 
penetration (i.e., ``high energy'') seismic survey, with no more than 
18 months elapsed since the conclusion of the at-sea experience. One 
visual PSO with such experience shall be designated as the lead for the 
entire protected species observation team. The lead PSO shall serve as 
primary point of contact for the vessel operator and ensure all PSO 
requirements per the IHA are met. To the maximum extent practicable, 
the experienced PSOs should be scheduled to be on duty with those PSOs 
with appropriate training but who have not yet gained relevant 
experience.
    During survey operations (e.g., any day on which use of the 
acoustic source is planned to occur, and whenever the acoustic source 
is in the water, whether activated or not), a minimum of two visual 
PSOs must be on duty and conducting visual observations at all times 
during daylight hours (i.e., from 30 minutes prior to sunrise through 
30 minutes following sunset). Visual monitoring of the exclusion and 
buffer zones must begin no less than 30 minutes prior to ramp-up and 
must continue until one hour after use of the acoustic source ceases or 
until 30 minutes past sunset. Visual PSOs shall coordinate to ensure 
360[deg] visual coverage around the vessel from the most appropriate 
observation posts, and shall conduct visual observations using 
binoculars and the naked eye while free from distractions and in a 
consistent, systematic, and diligent manner.
    PSOs shall establish and monitor the exclusion and buffer zones. 
These zones shall be based upon the radial distance from the edges of 
the acoustic source (rather than being based on the center of the array 
or around the vessel itself). During use of the acoustic source (i.e., 
anytime airguns are active, including ramp-up), detections of marine 
mammals within the buffer zone (but outside the exclusion zone) shall 
be communicated to the operator to prepare for the potential shutdown 
of the acoustic source.
    During use of the airgun (i.e., anytime the acoustic source is 
active, including ramp-up), 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 sighting rates and behavior with and 
without use of the acoustic source and between acquisition periods, to 
the maximum extent practicable.
    While the R/V Langseth is surveying in water depths of 200 m or 
less, a second vessel with additional PSOs would travel approximately 5 
km ahead of the R/V Langseth. Two PSOs would be on watch on the second 
vessel during all such survey operations and would alert PSOs on the R/
V Langseth of any marine mammal observations so that they may be 
prepared to initiate shutdowns.
    Visual PSOs on both vessels may be on watch for a maximum of four 
consecutive hours followed by a break of at least one hour between 
watches and may conduct a maximum of 12 hours of observation per 24-
hour period. Combined observational duties (visual and acoustic but not 
at same time) may not exceed 12 hours per 24-hour period for any 
individual PSO.

Passive Acoustic Monitoring

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

[[Page 19624]]

     Operations with an active acoustic source, but without an 
operating PAM system, do not exceed a cumulative total of five hours in 
any 24-hour period.

Establishment of Exclusion and Buffer Zones

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

Pre-Clearance and Ramp-Up

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

Shutdown

    The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array. Any PSO on 
duty will have the authority to delay the start of survey operations or 
to call for shutdown of the acoustic source if a marine mammal is 
detected within the applicable 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

[[Page 19625]]

below) is detected acoustically and localized within the applicable 
exclusion zone, the acoustic source will be shut down. When shutdown is 
called for by a PSO, the acoustic source will be immediately 
deactivated and any dispute resolved only following deactivation. 
Additionally, shutdown will occur whenever PAM alone (without visual 
sighting), confirms presence of marine mammal(s) in the EZ. If the 
acoustic PSO cannot confirm presence within the EZ, visual PSOs will be 
notified but shutdown is not required. L-DEO must also implement 
shutdown of the airgun array if killer whale vocalizations are 
detected, regardless of localization.
    Following a shutdown, airgun activity would not resume until the 
marine mammal has cleared the 500-m EZ. The animal would be considered 
to have cleared the 500-m EZ if it is visually observed to have 
departed the 500-m EZ, or it has not been seen within the 500-m EZ for 
15 min in the case of small odontocetes and pinnipeds, or 30 min in the 
case of mysticetes and large odontocetes, including sperm whales, pygmy 
sperm whales, dwarf sperm whales, pilot whales, beaked whales, false 
killer whales, and Risso's dolphins.
    The shutdown requirement can be waived for small dolphins if an 
individual is visually detected within the 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--Tursiops, Delphinus, 
Stenella, Lagenorhynchus, and Lissodelphis.
    We include this small dolphin exception because shutdown 
requirements for small dolphins under all circumstances represent 
practicability concerns without likely commensurate benefits for the 
animals in question. Small dolphins are generally the most commonly 
observed marine mammals in the specific geographic region and would 
typically be the only marine mammals likely to intentionally approach 
the vessel. As described above, auditory injury is extremely unlikely 
to occur for mid-frequency cetaceans (e.g., delphinids), as this group 
is relatively insensitive to sound produced at the predominant 
frequencies in an airgun pulse while also having a relatively high 
threshold for the onset of auditory injury (i.e., permanent threshold 
shift).
    A large body of anecdotal evidence indicates that small dolphins 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinoids (e.g., Barkaszi et al., 2012). The potential for 
increased shutdowns resulting from such a measure would require the 
Langseth to revisit the missed track line to reacquire data, resulting 
in an overall increase in the total sound energy input to the marine 
environment and an increase in the total duration over which the survey 
is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large delphinoids) are no more likely to incur 
auditory injury than are small dolphins, they are much less likely to 
approach vessels. Therefore, retaining a shutdown requirement for large 
delphinoids would not have similar impacts in terms of either 
practicability for the applicant or corollary increase in sound energy 
output and time on the water. We do anticipate some benefit for a 
shutdown requirement for large delphinoids in that it simplifies 
somewhat the total range of decision-making for PSOs and may preclude 
any potential for physiological effects other than to the auditory 
system as well as some more severe behavioral reactions for any such 
animals in close proximity to the source vessel.
    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 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, and Risso's dolphins, 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 A or Level B 
harassment zones. L-DEO must also implement shutdown if any of the 
following are observed at any distance:
     Any large whale (defined as a sperm whale or any mysticete 
species) with a calf (defined as an animal less than two-thirds the 
body size of an adult observed to be in close association with an 
adult;
     An aggregation of six or more large whales;
     A North Pacific right whale; and/or
     A killer whale of any ecotype.

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

[[Page 19626]]

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.

Operational Restrictions

    While the R/V Langseth is surveying in waters 200 m deep or less, 
survey operations will occur in daylight hours only (i.e., from 30 
minutes prior to sunrise through 30 minutes following sunset) to ensure 
the ability to use visual observation as a detection-based mitigation 
tool and to implement shutdown procedures for species or situations 
with additional shutdown requirements outlined above (e.g., killer 
whale of any ecotype, aggregation of six or more large whales, large 
whale with a calf).

Communication

    Each day of survey operations, L-DEO will contact NMFS Northwest 
Fisheries Science Center, NMFS West Coast Region, The Whale Museum, 
Orca Network, Canada's DFO and/or other sources to obtain near real-
time reporting for the whereabouts of Southern Resident killer whales.

Mitigation Measures Considered But Eliminated

    As stated above, in determining appropriate mitigation measures, 
NMFS considers the practicability of the measures for applicant 
implementation, which may include such things as cost or impact on 
operations. NMFS has proposed expanding critical habitat for Southern 
Resident killer whales to include marine waters between the 6.1-m depth 
contour and the 200-m depth contour from the U.S. international border 
with Canada south to Point Sur, California (84 FR 49214; September 19, 
2019). Though the proposed expansion has not been finalized, due to the 
habitat features of the area and the higher likelihood of occurrence 
within the area, NMFS considered implementing a closure area and 
prohibiting L-DEO from conducting survey operations between the 200-m 
isobath and the coastline. However, this measure was eliminated from 
consideration because the closure would not be practicable for L-DEO, 
as the primary purpose of their proposed survey is to investigate the 
geologic features that occur within that area. Therefore, NMFS is not 
proposing to exclude L-DEO from waters within the 200-m isobath for 
this survey.
    We have carefully evaluated the suite of mitigation measures 
described here and considered a range of other measures in the context 
of ensuring that we prescribe the means of effecting the least 
practicable adverse impact on the affected marine mammal species and 
stocks and their habitat. Based on our evaluation of the proposed 
measures, as well as other measures considered by NMFS described above, 
NMFS has preliminarily determined that the mitigation measures provide 
the means effecting the least practicable impact on the affected 
species or stocks and their habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, Section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104 (a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present in the 
proposed action area. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Vessel-Based Visual Monitoring

    As described above, PSO observations would take place during 
daytime airgun operations. During seismic operations, at least five 
visual PSOs would be based aboard the Langseth. Two visual PSOs would 
be on duty at all time during daytime hours, with an additional two 
PSOs on duty aboard a second scout vessel at all times during daylight 
hours when operating in waters shallower than 200 m. Monitoring shall 
be conducted in accordance with the following requirements:
     The operator shall provide PSOs with bigeye binoculars 
(e.g., 25 x 150; 2.7 view angle; individual ocular focus; height 
control) of appropriate quality (i.e., Fujinon or equivalent) solely 
for PSO use. These shall be pedestal-mounted on the deck at the most 
appropriate vantage point that provides for optimal sea surface 
observation, PSO safety, and safe operation of the vessel; and
     The operator will work with the selected third-party 
observer provider to ensure PSOs have all equipment (including backup 
equipment) needed to adequately perform necessary tasks, including 
accurate determination of distance and bearing to observed marine 
mammals.
    PSOs must have the following requirements and qualifications:
     PSOs shall be independent, dedicated, trained visual and 
acoustic PSOs and must be employed by a third-party observer provider;
     PSOs shall have no tasks other than to conduct 
observational effort (visual or acoustic), collect data, and 
communicate with and instruct relevant vessel crew with regard to the 
presence of protected species and mitigation requirements (including 
brief alerts regarding maritime hazards);
     PSOs shall have successfully completed an approved PSO 
training course appropriate for their designated task (visual or 
acoustic). Acoustic PSOs are required to complete specialized training 
for operating PAM systems and are encouraged to have familiarity with 
the vessel with which they will be working;

[[Page 19627]]

     PSOs can act as acoustic or visual observers (but not at 
the same time) as long as they demonstrate that their training and 
experience are sufficient to perform the task at hand;
     NMFS must review and approve PSO resumes accompanied by a 
relevant training course information packet that includes the name and 
qualifications (i.e., experience, training completed, or educational 
background) of the instructor(s), the course outline or syllabus, and 
course reference material as well as a document stating successful 
completion of the course;
     NMFS shall have one week to approve PSOs from the time 
that the necessary information is submitted, after which PSOs meeting 
the minimum requirements shall automatically be considered approved;
     PSOs must successfully complete relevant training, 
including completion of all required coursework and passing (80 percent 
or greater) a written and/or oral examination developed for the 
training program;
     PSOs must have successfully attained a bachelor's degree 
from an accredited college or university with a major in one of the 
natural sciences, a minimum of 30 semester hours or equivalent in the 
biological sciences, and at least one undergraduate course in math or 
statistics; and
     The educational requirements may be waived if the PSO has 
acquired the relevant skills through alternate experience. Requests for 
such a waiver shall be submitted to NMFS and must include written 
justification. Requests shall be granted or denied (with justification) 
by NMFS within one week of receipt of submitted information. Alternate 
experience that may be considered includes, but is not limited to (1) 
secondary education and/or experience comparable to PSO duties; (2) 
previous work experience conducting academic, commercial, or 
government-sponsored protected species surveys; or (3) previous work 
experience as a PSO; the PSO should demonstrate good standing and 
consistently good performance of PSO duties.
    For data collection purposes, PSOs shall use standardized data 
collection forms, whether hard copy or electronic. PSOs shall record 
detailed information about any implementation of mitigation 
requirements, including the distance of animals to the acoustic source 
and description of specific actions that ensued, the behavior of the 
animal(s), any observed changes in behavior before and after 
implementation of mitigation, and if shutdown was implemented, the 
length of time before any subsequent ramp-up of the acoustic source. If 
required mitigation was not implemented, PSOs should record a 
description of the circumstances. At a minimum, the following 
information must be recorded:
     Vessel names (source vessel and other vessels associated 
with survey) and call signs;
     PSO names and affiliations;
     Dates of departures and returns to port with port name;
     Date and participants of PSO briefings;
     Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort;
     Vessel location (latitude/longitude) when survey effort 
began and ended and vessel location at beginning and end of visual PSO 
duty shifts;
     Vessel heading and speed at beginning and end of visual 
PSO duty shifts and upon any line change;
     Environmental conditions while on visual survey (at 
beginning and end of PSO shift and whenever conditions changed 
significantly), including BSS and any other relevant weather conditions 
including cloud cover, fog, sun glare, and overall visibility to the 
horizon;
     Factors that may have contributed to impaired observations 
during each PSO shift change or as needed as environmental conditions 
changed (e.g., vessel traffic, equipment malfunctions); and
     Survey activity information, such as acoustic source power 
output while in operation, number and volume of airguns operating in 
the array, tow depth of the array, and any other notes of significance 
(i.e., pre-clearance, ramp-up, shutdown, testing, shooting, ramp-up 
completion, end of operations, streamers, etc.).
    The following information should be recorded upon visual 
observation of any protected species:
     Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
     PSO who sighted the animal;
     Time of sighting;
     Vessel location at time of sighting;
     Water depth;
     Direction of vessel's travel (compass direction);
     Direction of animal's travel relative to the vessel;
     Pace of the animal;
     Estimated distance to the animal and its heading relative 
to vessel at initial sighting;
     Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified) and the composition of the 
group if there is a mix of species;
     Estimated number of animals (high/low/best);
     Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
     Description (as many distinguishing features as possible 
of each individual seen, including length, shape, color, pattern, scars 
or markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
     Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding, 
traveling; as explicit and detailed as possible; note any observed 
changes in behavior);
     Animal's closest point of approach (CPA) and/or closest 
distance from any element of the acoustic source;
     Platform activity at time of sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other); and
     Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up) and time and location of the 
action.
    If a marine mammal is detected while using the PAM system, the 
following information should be recorded:
     An acoustic encounter identification number, and whether 
the detection was linked with a visual sighting;
     Date and time when first and last heard;
     Types and nature of sounds heard (e.g., clicks, whistles, 
creaks, burst pulses, continuous, sporadic, strength of signal); and
     Any additional information recorded such as water depth of 
the hydrophone array, bearing of the animal to the vessel (if 
determinable), species or taxonomic group (if determinable), 
spectrogram screenshot, and any other notable information.

Reporting

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

[[Page 19628]]

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;
     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 and North Pacific right 
whales to OPR, NMFS .

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

[[Page 19629]]

marine mammals that might be ``taken'' through harassment, NMFS 
considers other factors, such as the likely nature of any responses 
(e.g., intensity, duration), the context of any responses (e.g., 
critical reproductive time or location, migration), as well as effects 
on habitat, and the likely effectiveness of the mitigation. We also 
assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS's implementing regulations (54 FR 
40338; September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the environmental baseline (e.g., as reflected in the 
regulatory status of the species, population size and growth rate where 
known, ongoing sources of human-caused mortality, or ambient noise 
levels).
    To avoid repetition, our analysis applies to all species listed in 
Tables 10 and 11, given that NMFS expects the anticipated effects of 
the planned geophysical survey to be similar in nature. Where there are 
meaningful differences between species or stocks, or groups of species, 
in anticipated individual responses to activities, impact of expected 
take on the population due to differences in population status, or 
impacts on habitat, NMFS has identified species-specific factors to 
inform the analysis. As described above, we proposed to authorize only 
the takes estimated to occur outside of Canadian territorial waters 
(Table 10); however, for the purposes of our negligible impact analysis 
and determination, we consider the total number of takes that are 
anticipated to occur as a result of the entire proposed survey 
(including the portion of the survey that would occur within the 
Canadian territorial waters (approximately four percent of the survey) 
(Table 11).

                                          Table 11--Total Estimated Take Including Canadian Territorial Waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Estimated take (excluding       Estimated take (Canadian          Total estimated take
                                                           Canadian territorial waters)         territorial waters)      -------------------------------
                         Species                         ----------------------------------------------------------------
                                                              Level A         Level B         Level A         Level B         Level B         Level A
--------------------------------------------------------------------------------------------------------------------------------------------------------
LF Cetaceans:
    Humpback whale......................................             172              10              23               1             195              11
    Blue whale..........................................              63               4               8               0              71               4
    Fin whale...........................................              89               6               2               0              91               6
    Sei whale...........................................              32               2               2               0              34               2
    Minke whale.........................................             105               7               6               0             111               7
    Gray whale..........................................              90               2              24               1             114               3
MF Cetaceans:
    Sperm whale.........................................              71               0               1               0              72               0
    Baird's beaked whale................................              83               0               1               0              84               0
    Small beaked whale..................................             244               0               5               0             249               0
    Bottlenose dolphin..................................              13               0               0               0              13               0
    Striped dolphin.....................................               7               0               0               0               7               0
    Short-beaked common dolphin.........................             179               0               4               0             183               0
    Pacific white-sided dolphin.........................           6,452               0             354               0           6,806               0
    Northern right-whale dolphin........................           4,333               0             123               0           4,457               0
    Risso's dolphin.....................................           1,906               0             155               0           2,062               0
    False killer whale..................................               5               0               5               0              10               0
    Killer whale (Southern Resident)....................              43               0               2               0              45               0
    Killer whale (Northern Resident)....................              27               0               2               0              29               0
    Killer whale (West Coast Transient).................              26               0               2               0              28               0
    Killer whale (Offshore).............................              26               0               2               0              28               0
    Short-finned pilot whale............................              29               0               1               0              30               0
HF Cetaceans:
    Pygmy/dwarf sperm whale.............................             135               6               8               0             143               6
    Dall's porpoise.....................................          10,869             452             746              24          11,615             476
    Harbor porpoise.....................................          12,557             449           2,622              86          15,179             535
Otariid Seals:
    Northern fur seal...................................           4,604               0              58               0           4,662               0
    Guadalupe fur seal..................................           2,387               0             122               0           2,509               0
    California sea lion.................................           1,140               0             147               0           1,287               0
    Steller sea lion....................................           7,281               0           1,342               0           8,623               0
Phocid Seals:
    Northern elephant seal..............................           1,995               0             176               0           2,171               0
    Harbor seal.........................................           6,537               0           1,744               0           8,281               0
--------------------------------------------------------------------------------------------------------------------------------------------------------

    NMFS does not anticipate that serious injury or mortality would 
occur as a result of L-DEO's planned survey, even in the absence of 
mitigation, and none would be authorized. As discussed in the Potential 
Effects section, non-auditory physical effects, stranding, and vessel 
strike are not expected to occur.
    We are proposing to authorize a limited number of instances of 
Level A harassment of nine species (low- and high-frequency cetacean 
hearing groups only) and Level B harassment of 31 marine mammal 
species. However, we believe that any PTS incurred in marine mammals as 
a result of the planned activity would be in the form of only a small 
degree of PTS, not total deafness, because of the constant movement of 
relative to each other of both the R/V Langseth and of the marine 
mammals in the project areas, as well as the fact that the vessel is 
not expected to remain in any one area in which individual marine 
mammals would be expected to concentrate for an extended period of

[[Page 19630]]

time (i.e., since the duration of exposure to loud sounds will be 
relatively short) and, further, would be unlikely to affect the fitness 
of any individuals. Also, as described above, we expect that marine 
mammals would be likely to move away from a sound source that 
represents an aversive stimulus, especially at levels that would be 
expected to result in PTS, given sufficient notice of the R/V 
Langseth's approach due to the vessel's relatively low speed when 
conducting seismic surveys. We expect that the majority of takes would 
be in the form of short-term Level B behavioral harassment in the form 
of temporary avoidance of the area or decreased foraging (if such 
activity were occurring), reactions that are considered to be of low 
severity and with no lasting biological consequences (e.g., Southall et 
al., 2007, Ellison et al., 2012).
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see Potential Effects of the Specified 
Activity on Marine Mammals and their Habitat). Marine mammal habitat 
may be impacted by elevated sound levels, but these impacts would be 
temporary. Prey species are mobile and are broadly distributed 
throughout the project areas; therefore, marine mammals that may be 
temporarily displaced during survey activities are expected to be able 
to resume foraging once they have moved away from areas with disturbing 
levels of underwater noise. Because of the relatively short duration 
(37 days) and temporary nature of the disturbance, the availability of 
similar habitat and resources in the surrounding area, the impacts to 
marine mammals and the food sources that they utilize are not expected 
to cause significant or long-term consequences for individual marine 
mammals or their populations.
    The tracklines of this survey either traverse or are proximal to 
BIAs for humpback and gray whales (Ferguson et al., 2015). The entire 
U.S. West Coast within 47 km of the coast is a BIA for migrating gray 
whale potential presence from 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. There are four gray whale feeding 
BIAs within the proposed survey area: the Grays Harbor gray whale 
feeding BIA is used between April and November; the Northwest 
Washington gray whale feeding BIA is used between May and November; and 
the Depoe Bay and Cape Blanco and Orford Reef gray whale feeding BIAs 
off Oregon are each used between June and November. There are also two 
humpback whale feeding BIAs within the survey area: the Stonewall and 
Heceta Bank humpback whale feeding BIA off central Oregon and the 
northern Washington BIA off the Washington Olympic Peninsula are each 
used between May and November.
    For the humpback whale feeding and gray whale feeding and 
northbound migration BIAs, L-DEO's proposed survey beginning in June 
2020 could overlap with a period where BIAs represent an important 
habitat. However, only a portion of seismic survey days would actually 
occur in or near these BIAs, and all survey efforts would be completed 
by mid-July, still in the early window of primary use for these BIAs. 
Gray whales are most commonly seen migrating northward between March 
and May and southward between November and January. As proposed, there 
is no possibility that L-DEO's survey impacts the southern migration, 
and presence of northern migrating individuals should be below peak 
during survey operations beginning in June 2020.
    Although migrating gray whales may slightly alter their course in 
response to the survey, the exposure would not substantially impact 
their migratory behavior (Malme et al., 1984; Malme and Miles 1985; 
Richardson et al., 1995), and Yazvenko et al. (2007b) reported no 
apparent changes in the frequency of feeding activity in Western gray 
whales exposed to airgun sounds in their feeding grounds near Sakhalin 
Island. Goldbogen et al. (2013) found blue whales feeding on highly 
concentrated prey in shallow depths (such as the conditions expected 
within humpback feeding BIAs) were less likely to respond and cease 
foraging than whales feeding on deep, dispersed prey when exposed to 
simulated sonar sources, suggesting that the benefits of feeding for 
humpbacks foraging on high-density prey may outweigh perceived harm 
from the acoustic stimulus, such as the seismic survey (Southall et 
al., 2016). Additionally, L-DEO will shut down the airgun array upon 
observation of an aggregation of six or more large whales, which would 
reduce impacts to cooperatively foraging animals. For all habitats, no 
physical impacts to BIA habitat are anticipated from seismic 
activities. While SPLs of sufficient strength have been known to cause 
injury to fish and fish and invertebrate mortality, in feeding 
habitats, the most likely impact to prey species from survey activities 
would be temporary avoidance of the affected area and any injury or 
mortality of prey species would be localized around the survey and not 
of a degree that would adversely impact marine mammal foraging. The 
duration of fish avoidance of a given area after survey effort stops is 
unknown, but a rapid return to normal recruitment, distribution and 
behavior is expected. Given the short operational seismic time near or 
traversing BIAs, as well as the ability of cetaceans and prey species 
to move away from acoustic sources, NMFS expects that there would be, 
at worst, minimal impacts to animals and habitat within the designated 
BIAs.
    Critical habitat has been established on the U.S. West Coast for 
the eastern DPS of Steller sea lions (58 FR 45269; August 27, 1993) and 
in inland waters of Washington for Southern Resident killer whales (71 
FR 69054; November 29, 2006). Critical habitat for the Mexico and 
Central America DPSs of humpback whales has been proposed along the 
U.S. West Coast (84 FR 54354; October 9, 2019), and NMFS has proposed 
expanding Southern Resident killer whale critical habitat to include 
coastal waters of Washington, Oregon, and California (84 FR 49214; 
September 19, 2019). Only a portion of L-DEO's proposed seismic survey 
will occur in or near these critical habitats.
    Critical habitat for Steller sea lions has been established at two 
rookeries on the Oregon 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 rookeries (NMFS 1993). Steller sea lions 
occupy rookeries and pup from late-May through early-July (NMFS 2008), 
which coincides with L-DEO's proposed survey. The Orford Reef and Rogue 
Reef critical habitats are located 7 km and 9 km from the nearest 
proposed seismic transect line, respectively. Impacts to Steller sea 
lions within these areas, and throughout the survey area, are expected 
to be limited to short-term behavioral disturbance, with no lasting 
biological consequences.
    Critical habitat for the threatened Mexico DPS and endangered 
Central America DPS humpback whales has been proposed along the U.S. 
West Coast (84 FR 54354; October 9, 2019). The proposed critical 
habitat encompasses the humpback whale feeding BIAs described above and 
generally includes waters between the 50-m isobath and the 1,200-m 
isobath, though some areas of the proposed critical habitat extend 
further offshore. NMFS determined that prey within humpback whale 
feeding areas are

[[Page 19631]]

essential to the conservation of each of the three DPSs of humpback 
whales for which critical habitat was proposed (Mexico, Central 
America, and Western North Pacific DPSs). Critical habitat was 
therefore proposed in consideration of importance that the whales not 
only have reliable access to prey within their feeding areas, but that 
prey are of a sufficient density to support feeding and the build-up of 
energy reserves. Although humpback whales are generalist predators and 
prey availability can very seasonally and spatially, substantial data 
indicate that the humpback whales' diet is consistently dominated by 
euphausiid species (of genus Euphausia, Thysanoessa, Nyctiphanes, and 
Nematoscelis) and small pelagic fishes, such as northern anchovy 
(Engraulis mordax), Pacific herring (Clupea pallasii), Pacific sardine 
(Sardinops sagax), and capelin (Mallotus villosus) (Nemoto 1957, 1959; 
Klumov 1963; Rice Krieger and Wing 1984; Baker 1985; Kieckhefer 1992; 
Clapham et al., 1997; Neilson et al., 2015). While there are possible 
impacts of seismic activity on plankton and fish species (e.g., 
McCauley et al., 2017; Hastings and Popper 2005), the areas expected to 
be affected by L-DEO's activities are small relative to the greater 
habitat areas available.
    Additionally, humpback whales feeding on high-density prey may be 
less likely to cease foraging when the benefit of energy intake 
outweighs the perceived harm from acoustic stimulus (Southall et al., 
2016). Therefore, this seismic activity is not expected to have a 
lasting physical impact on humpback whale proposed critical habitat, 
prey within it, or overall humpback whale fitness. Any impact would be 
a temporary increase in sound levels when the survey is occurring in or 
near the critical habitat and resulting temporary avoidance of prey or 
marine mammals themselves due these elevated sound levels. As stated 
above, L-DEO will shut down the airgun array upon observation of an 
aggregation of six or more large whales, which would reduce direct 
impacts to groups of humpback whales that may be cooperatively feeding 
in the area.

Southern Resident Killer Whales

    In acknowledgment of our concern regarding the status of Southern 
Resident killer whales, including low abundance and decreasing trend, 
we address impacts to this stock separately in this section.
    L-DEO's proposed tracklines do not overlap with existing Southern 
Resident killer whale habitat, but NMFS has proposed expanding Southern 
Resident critical habitat to include waters between the 6.1-m and 200-m 
depth contours from the U.S. international border with Canada south to 
Point Sur, California (84 FR 49214; September 19, 2019). The proposed 
expanded critical habitat areas were identified in consideration of 
physical and biological features essential to conservation of Southern 
Resident killer whales (essential features): (1) Water quality to 
support growth and development; (2) Prey species of sufficient 
quantity, quality, and availability to support individual growth, 
reproduction, and development, as well as overall population growth; 
and (3) Passage conditions to allow for migration, resting, and 
foraging. NMFS did not identify in-water sound levels as a separate 
essential feature of existing or proposed expanded critical habitat 
areas, though anthropogenic sound is recognized as one of the primary 
threats to Southern Resident killer whales (NMFS 2019). Exposure to 
vessel noise and presence of whale watching boats can significantly 
affect the foraging behavior of Southern Resident killer whales 
(Williams et al., 2006; Lusseau et al., 2009; Giles and Cendak 2010; 
Senigaglia et al., 2016). Nutritional stress has also been identified 
as a primary cause of Southern Resident killer whale decline (Ayres et 
al., 2012; Wasser et al., 2017), suggesting that reduced foraging 
effort may have a greater impact than behavioral disturbance alone. 
However, these studies have primarily focused on effects of whale watch 
vessels operating in close proximity to Southern Resident killer 
whales, and commercial shipping traffic in the Salish Sea (i.e., the 
inland waters of Washington and British Columbia). Commercial whale 
watch and private recreational vessels operating in the waters around 
the San Juan Islands in summer months number in the dozens (Erbe 2002), 
and at least 400 piloted vessels (commercial vessels over 350 gross 
tons and pleasure craft over 500 gross tons that are required to be 
guided in and out of the Port of Vancouver by British Columbia Coast 
Pilots) transit through Haro Strait each month (Joy et al., 2002). 
Concentration of vessel traffic on the outer coast, where the proposed 
survey area occurs, is much lower than in the inland waters (Cominelli 
et al., 2018), suggesting that effects from vessel noise may be lower 
than in inland waters. Increased noise levels from the proposed survey 
in any specific area would be short-term due to the mobile nature of 
the survey, unlike the near-constant vessel presence in inland waters.
    Approximately 23 percent of L-DEO's total tracklines occur within 
the 200-m isobath along Washington and Oregon. L-DEO would be required 
to shut down seismic airguns immediately upon visual observation or 
acoustic detection of killer whales of any ecotype at any distance to 
minimize potential exposures of Southern Resident killer whales, and 
will operate within the 200-m isobath in daylight hours only, to 
increase the ability to visually detect killer whales and implement 
shutdowns. Southern Resident killer whales exposed to elevated sound 
levels from the R/V Langseth and the airgun array may reduce foraging 
time, but the amount of tracklines that overlap with the areas of 
highest estimated densities of Southern Resident killer whales (see 
Figures 7-9 and 7-11 in the U.S. Navy's MSDD (U.S. Navy 2019)) is low 
relative to the total survey effort. Approximately 360 km of survey 
tracklines occur within the areas of highest Southern Resident killer 
whale density (the three highest density ranges for each pod), which 
represents approximately 5 percent of the total survey tracklines, or 
just under two days of survey operations. If Southern Resident killer 
whales are encountered during the survey in these areas and reduce 
foraging effort in response, the relatively small amount of time of 
altered behavior would not likely affect their overall foraging 
ability. While Southern Resident killer whales may be encountered 
outside of these areas of highest density, the likelihood is 
significantly decreased and thus the likelihood of impacts to foraging 
is decreased. Short-term impacts to foraging ability are not likely to 
result in significant or lasting consequences for individual Southern 
Resident killer whales or the population as a whole (Ayres et al., 
2012). Due to the mobile nature of the survey, animals would not be 
exposed to elevated sounds for an extended period, and the proposed 
critical habitat contains a large area of suitable habitat that would 
allow Southern Resident killer whales to forage away from the survey. 
Noren et al. (2016) reported that although resident killer whales 
increase energy expenditure in response to vessel presence, the 
increase is considered to be negligible.
    No permanent hearing impairment (Level A harassment) is anticipated 
or proposed to be authorized. Authorized takes of Southern Resident 
killer whales would be limited to Level B harassment in the form of 
behavioral disturbance. We anticipate 45 instances of Level B

[[Page 19632]]

harassment of Southern Resident killer whales, which we expect would 
likely occur to a smaller subset of the population on only a few days. 
Limited, short term behavioral disturbance of the nature expected here 
would not be expected to result in fitness-level effects to individual 
Southern Resident killer whales or the population as a whole.

Negligible Impact Conclusions

    The proposed survey would be of short duration (37 days of seismic 
operations), and the acoustic ``footprint'' of the proposed survey 
would be small relative to the ranges of the marine mammals that would 
potentially be affected. Sound levels would increase in the marine 
environment in a relatively small area surrounding the vessel compared 
to the range of the marine mammals within the proposed survey area. 
Short term exposures to survey operations are not likely to 
significantly disrupt marine mammal behavior, and the potential for 
longer-term avoidance of important areas is limited.
    The proposed mitigation measures are expected to reduce the number 
and/or severity of takes by allowing for detection of marine mammals in 
the vicinity of the vessel by visual and acoustic observers, and by 
minimizing the severity of any potential exposures via shutdowns of the 
airgun array. Based on previous monitoring reports for substantially 
similar activities that have been previously authorized by NMFS, we 
expect that the proposed mitigation will be effective in preventing, at 
least to some extent, potential PTS in marine mammals that may 
otherwise occur in the absence of the proposed mitigation (although all 
authorized PTS has been accounted for in this analysis). Further, for 
Southern Resident Killer Whales (as described above), additional 
mitigation (e.g., second monitoring vessel, daylight only surveys) is 
expected to increase the ability of PSOs to detect killer whales and 
shut down the airgun array to reduce the instances and severity of 
behavioral disturbance.
    NMFS concludes that exposures to marine mammal species and stocks 
due to L-DEO's proposed survey would result in only short-term 
(temporary and short in duration) effects to individuals exposed, over 
relatively small areas of the affected animals' ranges. Animals may 
temporarily avoid the immediate area, but are not expected to 
permanently abandon the area. Major shifts in habitat use, 
distribution, or foraging success are not expected. NMFS does not 
anticipate the proposed take estimates to impact annual rates of 
recruitment or survival.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or proposed 
to be authorized;
     The proposed activity is temporary and of relatively short 
duration (37 days);
     The anticipated impacts of the proposed activity on marine 
mammals would primarily be temporary behavioral changes due to 
avoidance of the area around the survey vessel;
     The number of instances of potential PTS that may occur 
are expected to be very small in number. Instances of potential PTS 
that are incurred in marine mammals are expected to be of a low level, 
due to constant movement of the vessel and of the marine mammals in the 
area, and the nature of the survey design (not concentrated in areas of 
high marine mammal concentration);
     The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the proposed survey to avoid exposure to sounds from the activity;
     The potential adverse effects on fish or invertebrate 
species that serve as prey species for marine mammals from the proposed 
survey would be temporary and spatially limited, and impacts to marine 
mammal foraging would be minimal; and
     The proposed mitigation measures, including visual and 
acoustic monitoring, 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).
     Additionally as described above for Southern Resident 
killer whales specifically, anticipated impacts are limited to few days 
of behavioral disturbance for any one individual and additional 
mitigation (e.g., additional monitoring vessel, survey timing, 
shutdowns) are expected to ensure that both the numbers and severity of 
impacts to this stock are minimized, and, therefore the proposed 
authorization of Southern Resident killer whale take is not expected 
impact the fitness of any individuals, much less rates of recruitment 
or survival.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed mitigation and 
monitoring measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. Additionally, other qualitative 
factors may be considered in the analysis, such as the temporal or 
spatial scale of the activities.
    There are several stocks for which the estimated instances of take 
appear high when compared to the stock abundance (Table 10), including 
the Southern Resident killer whale stock, the California/Oregon/
Washington Dall's porpoise stock, and the Northern California/Southern 
Oregon and Northern Oregon/Washington Coast harbor porpoise stocks. 
However, when other qualitative factors are used to inform an 
assessment of the likely number of individual marine mammals taken, the 
resulting numbers are appropriately considered small. We discuss these 
in further detail below.
    For all other stocks (aside from the four referenced above and 
described below), the proposed take is less than one-third of the best 
available stock abundance (recognizing that some of those takes may be 
repeats of the same individual, thus rendering the actual percentage 
even lower).
    The expected take of Southern Resident killer whales, as a 
proportion of the population abundance, is 57.33 percent, if all takes 
are assumed to occur for unique individuals. In their NWTT Phase III 
MSDD, the U.S. Navy created density estimates of Southern Resident 
killer whales in their Offshore Study Area (U.S. Navy 2019). These 
density estimates were developed with the assumption that all members 
of the Southern Resident population were within the Study Area (i.e., 
no Southern Resident killer whales were assumed to be in the inland 
waters of the Salish Sea). In reality, Southern Resident killer whales 
have historically spent much of

[[Page 19633]]

their time in the Salish Sea from spring through fall to forage on 
Fraser River Chinook salmon (Shields et al., 2017) and it is likely 
that some or all of the population may be in inland waters during the 
proposed survey. Therefore, we expect that there will be multiple takes 
of a smaller number of individuals within the action area, such that 
the number of individuals taken will be less than one-third of the 
population.
    The expected take of the California/Oregon/Washington stock of 
Dall's porpoises, as a proportion of the population abundance, is 40.8 
percent, if all takes are assumed to occur for unique individuals. In 
reality, it is unlikely that all takes would occur to different 
individuals. L-DEO's proposed survey area represents a small portion of 
the stock's overall range (Caretta et al., 2017), and it is more likely 
that there will be multiple takes of a smaller number of individuals 
within the action area. In addition, Best et al. (2015) estimated the 
population of Dall's porpoise in British Columbia to be 5,303 porpoises 
based on systematic line-transect surveys of the Strait of Georgia, 
Johnstone Strait, Queen Charlotte Sound, Hecate Strait, and Dixon 
Entrance between 2004 and 2007. In consideration of the greater 
abundance estimate combining the U.S. stock and animals in British 
Columbia, and the likelihood of repeated takes of individuals, it is 
unlikely that more than one-third of the stock would be exposed to the 
seismic survey.
    When assuming all takes of harbor porpoise would occur to either 
the Northern Oregon/Washington Coast or Northern California/Southern 
Oregon stocks, the take appears high relative to stock abundance (60.53 
and 36.36 percent, respectively). In reality, takes will occur to both 
stocks, and therefore, the number of takes of each stock will be much 
lower. NMFS has no commonly used method to estimate the relative 
proportion of each stock that would experience take, but here we 
propose to apportion the takes between the two stocks based on the 
stock boundary (Lincoln City, Oregon) and the approximate proportion of 
the survey area that will occur on either side of the stock boundary. 
North of Lincoln City, Oregon, harbor porpoises belong to the Northern 
Oregon/Washington Coast stock, and south of Lincoln City, harbor 
porpoises belong to the Northern California/Southern Oregon stock. 
Approximately one-third of the proposed survey occurs south of Lincoln 
City, therefore one-third of the total estimated takes are assumed to 
be from the Northern California/Southern Oregon stock. The remaining 
two-thirds of the estimated takes are assumed to be from the Northern 
Oregon/Washington Coast stock. The estimated one-third of total takes 
assigned to the Northern California/Southern Oregon stock (4,335 total 
Level A and Level B takes) represent 12.12 percent of the stock 
abundance, which NMFS considers to be small relative to the stock 
abundance. In addition, the proposed survey area represents a small 
portion of the stock's range, and it is likely that there will be 
multiple takes of a small portion of individuals, further reducing the 
number of individuals exposed. The estimated two-thirds of total takes 
assigned to the Northern Oregon/Washington Coast stock (8,671 takes) 
represent 40.35 percent of the stock abundance, which is still 
considered high relative to stock abundance. However, the Northern 
Oregon/Washington Coast stock abundance estimate does not include 
animals in Canadian waters (Caretta et al., 2017). Best et al. (2015) 
estimated a population abundance of 8,091 harbor porpoises in British 
Columbia. The estimated takes of animals in the northern portion of the 
survey area (north of Lincoln City) represent 29.32 percent of the 
combined British Columbia and Northern Oregon/Washington Coast 
abundance estimates, which NMFS considers to be small relative to 
estimated abundance.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals will be taken relative to the population size 
of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
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 (ESA)

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

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to L-DEO for conducting a marine geophysical survey in the 
northeast Pacific Ocean beginning in June 2020, provided the previously 
mentioned mitigation, monitoring, and reporting requirements are 
incorporated. A draft of the proposed IHA can be found at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this Notice of Proposed IHA for the proposed 
geophysical survey. We also request at this time comment on the 
potential Renewal of this proposed IHA as described in the paragraph 
below. Please include with your comments any supporting data or 
literature citations to help inform decisions on the request for this 
IHA or a subsequent Renewal IHA.
    On a case-by-case basis, NMFS may issue a one-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 Specified Activities section 
of this notice is planned or (2) the activities as described in the 
Specified 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

[[Page 19634]]

that the Renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA);
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested Renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take); 
and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
     Upon review of the request for Renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: April 1, 2020.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2020-07289 Filed 4-6-20; 8:45 am]
 BILLING CODE 3510-22-P