[Federal Register Volume 86, Number 102 (Friday, May 28, 2021)]
[Notices]
[Pages 29090-29133]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-11375]



[[Page 29089]]

Vol. 86

Friday,

No. 102

May 28, 2021

Part III





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. 86, No. 102 / Friday, May 28, 2021 / 
Notices  

[[Page 29090]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XA144]


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; issuance of an incidental harassment authorization.

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SUMMARY: In accordance with the regulations implementing the Marine 
Mammal Protection Act (MMPA) as amended, notification is hereby given 
that NMFS has issued an incidental harassment authorization (IHA) to 
Lamont-Doherty Earth Observatory of Columbia University (L-DEO) to 
incidentally harass, by Level A and Level B harassment, marine mammals 
during a marine geophysical survey in the northeast Pacific Ocean.

DATES: This Authorization is effective from May 19, 2021 through May 
18, 2022.

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.

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. NMFS 
published a notice of proposed IHA for public review and comment on 
April 7, 2020 (85 FR 19580). On May 29, 2020, L-DEO informed NMFS that 
the project had been delayed by one year and would begin in June 2021.

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 National Science Foundation (NSF), and in 
collaboration with researchers from Dalhousie University and Simon 
Fraser University (SFU) plan 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 2021. The seismic survey will 
be conducted at the Cascadia Subduction Zone off the coasts of Oregon, 
Washington, and British Columbia, Canada. The proposed two-dimensional 
(2-D) seismic survey will occur within the Exclusive Economic Zones 
(EEZs) of Canada and the United States, including U.S. state waters and 
Canadian territorial waters. The survey will 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 planned study will 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 will provide essential constraints for 
earthquake and tsunami hazard assessment in this heavily populated 
region of the Pacific Northwest. The primary objectives of the survey 
planned 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 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 will likely leave out of and return to port in Newport, 
Oregon, during June-July 2021.

Specific Geographic Region

    The survey will occur within ~42-51[deg] N, ~124-130[deg] W. 
Planned 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 will 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 6,540 
kilometers (km) of transect lines will be surveyed. Most of the survey 
(69 percent) will occur in deep water (>1,000 m), 28 percent will occur 
in intermediate water (100-1,000 m deep), and 3 percent will take place 
in shallow water <100 m deep. Approximately 3.6 percent of the transect 
lines (234 km) will be undertaken in Canadian territorial waters (from 
0-12 nautical miles (22.2 km) from shore), with most

[[Page 29091]]

effort in intermediate water depths. 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 determination under the MMPA that the activity will have 
a negligible impact on the affected species.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN28MY21.012

BILLING CODE 3510-22-C

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Detailed Description of Specific Activity

    The procedures to be used for the planned survey will be similar to 
those used during previous seismic surveys by L-DEO and will use 
conventional seismic methodology. The surveys will involve one source 
vessel, R/V Langseth. R/V Langseth will 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 will be approximately 4.2 knots 
(~7.8 km/hour) during the survey and the airgun array will be towed at 
a depth of 12 m. The receiving system will consist of one 15-km long 
hydrophone streamer, OBSs, and OBNs. R/V Oceanus, which is owned by NSF 
and operated by Oregon State University, will be used to deploy the 
OBSs and OBNs. As the airguns are towed along the survey lines, the 
hydrophone streamer will transfer the data to the on-board processing 
system, and the OBSs and OBNs will receive and store the returning 
acoustic signals internally for later analysis.
    Long 15-km-offset multichannel seismic (MCS) data will be acquired 
along numerous 2-D profiles oriented perpendicular to the margin and 
located to provide coverage in areas inferred to be rupture patches 
during past earthquakes and their boundary zones. The survey will 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 will 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. L-DEO 
plans to survey the southern transects off Oregon first, followed by 
the profiles off Washington and Vancouver Island, British Columbia.
    The OBSs will 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 will be deployed at 10-km spacing 
along ~10 profiles from Vancouver Island to Oregon, and OBNs will be 
deployed at a 500-m spacing along a portion of three profiles off 
Oregon. Two OBS deployments will occur with a total of 115 instrumented 
locations. 60 OBSs will 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 will occur prior to the start of the planned survey, after which 
R/V Langseth will acquire data in the southern portion of the study 
area. R/V Oceanus will 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 kilohertz 
(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 will be deployed: 179 nodes along one transect 
off northern Oregon, 107 nodes along a second transect off central 
Oregon, and 64 nodes along a third transect off southern 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 will be deployed and retrieved using a remotely 
operated vehicle (ROV); the ROV will be deployed from R/V Oceanus. OBNs 
will be deployed approximately 17 days prior to the start of the R/V 
Langseth cruise. The ROV will 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 will be retrieved, the skid will be reloaded with 
another 32 units, and sent back to the seafloor for deployment, and so 
on. The ROV will recover the nodes 3 days after the completion of the 
R/V Langseth cruise. The nodes will 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) will 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 will be conducted by L-DEO with on-board assistance by the 
scientists who have planned the studies. The vessel will be self-
contained, and the crew will 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. Mitigation, 
monitoring, and reporting measures are described in detail later in 
this document (please see Mitigation and Monitoring and Reporting).

Comments and Responses

    A notice of NMFS's proposal to issue an IHA to L-DEO was published 
in the Federal Register on April 7, 2020 (85 FR 19580). During the 
public comment period, NMFS received comment letters from the Marine 
Mammal Commission (Commission), Ecojustice (on behalf of the David 
Suzuki Foundation, Georgia Strait Alliance, Raincoast Conservation 
Foundation, and World Wildlife Fund Canada), Deep Green Wilderness, and 
a group of environmental non-governmental organizations (ENGOs) 
including the Center for Biological Diversity (CBD), Natural Resources 
Defense Council, Orca Relief Citizens Alliance, Friends of the San 
Juans, Whale and Dolphin Conservation, Friends of the Earth, Oceana, 
and Orca Conservancy. NMFS has posted the comments online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. Please see the 
letters for full details and rationale. A summary of the comments and 
our responses are provided here.
    Comment 1: Ecojustice requested NMFS deny L-DEO's request for an 
IHA

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because the survey will affect Southern Resident killer whale critical 
habitat (e.g., Swiftsure and La Perouse Banks) designated in Canada 
under the Canadian Species at Risk Act (SARA). The commenter asserts 
that noise production in these areas will both harm or harass 
individuals and constitute destruction of a portion of Canadian 
critical habitat.
    Response: This comment is beyond the scope of NMFS' proposed 
action, which is to authorize take of marine mammals incidental to the 
proposed survey. NMFS does not allow or deny the survey itself, and 
NMFS' action of authorizing incidental take does not cause effects to 
critical habitat (in Canada or the U.S.). However, as part of their 
consultation with Canada's Department of Fisheries and Oceans (DFO) 
under Canada's SARA, L-DEO has removed all survey tracklines with 
associated ensonified areas that overlap with Canadian designated 
killer whale critical habitat at Swiftsure and La Perouse Bank (see 
Figure 1); therefore, the Canadian critical habitat will not be subject 
to destruction.
    Comment 2: Ecojustice asserts that the critically endangered status 
of Southern Resident killer whales means there is no acceptable level 
of take for the species. Similarly, the ENGOs recommended NMFS not 
issue any take authorization until it has effectively reduced the take 
of Southern Resident killer whales to zero, citing concern that 
behavioral disturbance can interfere with reproduction and survival due 
to lost foraging time.
    Response: NMFS disagrees that there is no acceptable level of take 
for Southern Resident killer whales, and the commenters have not 
demonstrated that any level of taking of Southern Resident killer 
whales would result in greater than a negligible impact on the stock. 
However, we do agree that additional effort to reduce impacts to 
Southern Resident killer whales is warranted to minimize to the extent 
practicable the amount of taking as well as the impact of taking that 
is authorized. In addition to removing tracklines within Canadian 
designated Southern Resident killer whale critical habitat at Swiftsure 
and La Perouse Banks (discussed above), L-DEO has removed and modified 
tracklines between Tillamook Head, Oregon and Barkley Sound, British 
Columbia, the area in which Southern Resident killer whales have the 
highest estimated densities (U.S. Navy 2019) and high-use foraging 
areas (NMFS 2019). The effect of these modifications to the survey plan 
is that, between these landmarks, the estimated Level B harassment 
ensonified area will not extend into water shallower than the 100-m 
depth contour. As a result, the total estimated take of Southern 
Resident killer whales has been reduced from 43 takes by Level B 
harassment in the proposed IHA (with an additional two takes within 
Canadian territorial waters, outside NMFS' jurisdiction) to 10 takes by 
Level B harassment (plus one take by Level B harassment within Canadian 
territorial waters), which is less than the population of any pod in 
the Southern Resident stock. This estimated take represents either 10 
individual Southern Resident killer whales taken by Level B harassment 
once over the course of the survey, or a smaller number of individuals 
taken multiple times (e.g., a single matriline of five animals taken by 
Level B harassment on two separate days). By avoiding surveying in the 
areas with highest expected Southern Resident killer whale presence and 
foraging rates, the likelihood of survey activities resulting in 
interference in feeding and migration that could result in lost feeding 
opportunities or necessitate additional energy expenditure to find 
other good foraging opportunities or migration routes is greatly 
reduced. Procedural mitigations that avoid the likelihood of injury, 
such as shutdown measures, also further reduce the likelihood of more 
severe behavioral responses.
    Comment 3: The ENGOs assert that NMFS inadequately considered the 
impacts of the proposed action on prey availability for Southern 
Resident killer whales, citing studies showing responses of fish to 
sound from seismic surveys. The ENGOs also state that NMFS must also 
consider the fitness of salmon being indirectly affected by the 
survey's impacts on herring, a key prey species for Pacific salmon.
    Response: NMFS disagrees with the suggestion that we ignored 
effects to prey species. In fact, we considered relevant literature 
(including that cited by the ENGOs) in finding that the most likely 
impact of survey activity to prey species such as fish and 
invertebrates would be temporary avoidance of an area, with a rapid 
return to pre-survey distribution and behavior, and minimal impacts to 
recruitment or survival anticipated. While there is a lack of specific 
scientific information to allow an assessment of the duration, 
intensity, or distribution of effects to prey in specific locations at 
specific times and in response to specific surveys, NMFS' review of the 
available information does not indicate that such effects could be 
significant enough to impact marine mammal prey to the extent that 
marine mammal fitness would be affected. We agree that seismic surveys 
could affect certain marine mammal prey species, and addressed these 
potential effects, as well as the potential for those effects to impact 
marine mammal populations, in our notice of proposed IHA (85 FR 19580; 
April 7, 2020). As stated in the notice of proposed IHA, our review of 
the available information and the specific nature of the activities 
considered herein suggest that L-DEO's proposed survey activities are 
not likely to have more than short-term adverse effects on any prey 
habitat or populations of prey species. Further, any impacts to prey 
species are not expected to result in significant or long-term 
consequences for individual marine mammals, or to contribute to adverse 
impacts on their populations.
    For additional information on the effects of L-DEO's proposed 
survey on salmon species present in the survey area, we refer the 
reader to the Biological Opinion issued by the NMFS Office of Protected 
Resources, Interagency Cooperation Division (available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities). In summary, 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. While we agree that some 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), our review shows that the weight of evidence 
indicates either no or only a 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 may be impacts to fish 
as a result of noise from nearby airguns, any 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

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et al., 1996; Engas and Lokkeborg, 2002). Other studies have reported 
similar findings (e.g., 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).
    Sound pressure levels (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. (2012) showed that a temporary 
threshold shift (TTS) of 4-6 decibel (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 surveys that are 
necessarily transient in any given location and likely result in brief, 
infrequent noise exposure to prey species in any given area. For these 
surveys, 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.
    NMFS considered the research referenced by the ENGOs and disagrees 
with the assertion that ``[NMFS] irrationally discounts those 
impacts,'' as well as with the commenters' interpretation of the 
literature. 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. Regarding Paxton et al. (2017), which describes 
findings related to the effects of a 2014 seismic survey on a reef off 
of North Carolina, while the study did show 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 because 
fish may remain present yet not be recorded on video. In summary, this 
particular study corroborates prior studies demonstrating a startle 
response or short-term displacement.
    The Carroll et al. (2017) 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. 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, the scientific literature demonstrates that impacts of 
seismic surveys 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 surveys, a rapid return to normal 
recruitment, distribution, and behavior for prey species is 
anticipated, and, overall, impacts to prey species, if any, 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 a given survey area would be temporary avoidance of the 
area. Surveys using towed airgun arrays move through an area relatively 
quickly, limiting exposure to multiple impulsive sounds. In all cases, 
sound levels would return to ambient once a 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 most surveys and the 
likelihood of temporary avoidance behavior suggest that impacts would 
be minor.
    NMFS believes that no evidence is presented to contradict our 
conclusions regarding likely impacts to marine mammals due to effects 
on prey species, i.e., 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, and that any effects that do occur are 
not expected to result in significant or long-term consequences for 
individual marine mammals, or to contribute to adverse impacts on their 
populations.
    Finally, we note that the National Science Foundation (NSF) is 
funding a study run by Oregon State University to assess the effects of 
L-DEO's survey activities on rockfish, Dungeness crab, and longnose 
skate. While the species chosen for this study do not represent 
important prey species for Southern Resident killer whales, which were 
the primary concern of the ENGOs, the study will provide important 
information on the effects of seismic surveys on nearshore species.
    Comment 4: The ENGOs commented that in making the negligible impact 
determination, NMFS underestimated the potential harm to the relevant 
stocks and distinct population segments (DPSs) of humpback whales, 
adding that the stock definitions for humpback whales are outdated and 
should match the DPSs as defined under the Endangered Species Act. The 
ENGOs assert that the takes proposed by NMFS are more than

[[Page 29095]]

negligible for the California/Oregon/Washington stock because the 
annual rate of serious injury and mortality (40.2 humpback whales per 
year) exceeds the potential biological removal (PBR; 33.4 humpbacks per 
year). Additionally, for both humpback and blue whales, the ENGOs 
assert that take by Level A harassment in the form of permanent hearing 
impairment amounts to serious injury, therefore the negligible impact 
determination overly relies on the assumption that there will be no 
serious injury or mortality from the seismic survey.
    Response: First, NMFS agrees that the alignment of MMPA stocks and 
Endangered Species Act (ESA) DPSs of humpback whales is important, and 
is actively working on rectifying the differences between stocks and 
DPSs. However, this issue is outside the scope of the action considered 
here. NMFS disagrees with the ENGOs' assertion that the authorized take 
of humpback or blue whales (or any species of marine mammal) by Level A 
harassment constitutes serious injury or has any relation to the PBR of 
the stock. PBR is defined in the MMPA (16 U.S.C. 1362(20)) 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'' and is a measure 
to be considered when evaluating the effects of mortality or serious 
injury on a marine mammal species or stock. There is no evidence that 
permanent threshold shift (PTS) can lead to mortality such that it 
should be considered ``serious injury'' or ``removing'' an individual 
from a stock. Therefore, it is not appropriate to use the PBR metric to 
directly evaluate the effects of Level A harassment (e.g., PTS) on a 
stock in the manner suggested by the ENGOs. Given the short duration of 
exposure, only low levels of hearing impairment are likely to occur, 
and would not affect the fitness of individual marine mammals or 
populations.
    As noted above, the PBR metric concerns levels of allowable 
removals from a population. Therefore, the PBR metric is not directly 
related to an assessment of negligible impact for this specified 
activity, which does not involve any expected potential for serious 
injury or mortality. PBR is not an appropriate metric with which to 
evaluate Level B harassment. However, we appropriately do consider 
levels of ongoing anthropogenic mortality from other sources, such as 
vessel strike, in relation to calculated PBR values as an important 
contextual factor in our negligible impact analysis, but a direct 
comparison of takes by harassment to the PBR value is not germane. 
While it is conceptually possible to link disturbance to potential 
fitness impacts to individuals over time (e.g., population consequences 
of disturbance), we have no evidence that is the case here and the take 
authorized here is not expected to affect the reproduction or 
survivorship of any individual marine mammals.
    Comment 5: The ENGOs assert that the negligible impact 
determination also relies on an expectation that marine mammals would 
be likely to move away from the sound source, which contradicts other 
statements from the notice of proposed IHA that avoidance is not 
assumed to occur because ``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.'' The commenters go 
on to state that animals avoiding the sound source still provokes an 
adverse behavioral reaction which displaces the animal from preferred 
habitat and potentially toward predators or shore with a risk of 
stranding.
    Response: NMFS does not rely on avoidance behaviors to make its 
negligible impact determination. NMFS agrees that avoidance of 
preferred habitat may temporarily limit optimal feeding or other 
biologically important behaviors. NMFS does not adjust take estimates 
based on the assumption that marine mammals would avoid the area, as 
the avoidance itself may constitute behavioral harassment. However, 
avoiding the sound source prevents the animal from exposure to the 
highest source levels, reducing the likelihood of temporary (Level B 
harassment) or permanent hearing impairment (Level A harassment), and 
reducing the intensity and/or duration of the harassment event. The 
avoidance is expected to be temporary, and animals are likely to return 
to the area after the survey vessel has passed through. In 
consideration of the likelihood of animals to independently avoid the 
sound source, and the mitigation requirements to shut down the airgun 
array if animals do approach within a certain distance, NMFS finds that 
the level of take expected to result from the survey is unlikely to 
have any impact on fitness or reproduction of individual animals, let 
alone populations.
    Comment 6: Citing studies suggesting that blue whales are 
especially sensitive to high intensity anthropogenic noise, such as 
mid-frequency sonar (e.g., Goldbogen et al., 2013), the ENGOs suggest 
that NMFS' consideration of the impact of the proposed activities on 
blue whales may underestimate the adverse impacts on the stock.
    Response: As discussed in the notice of proposed IHA, Goldbogen et 
al. (2013) found blue whales feeding on highly concentrated prey in 
shallow depths 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 blue whales 
foraging on high-density prey may outweigh perceived harm from the 
acoustic stimulus, such as the seismic survey. Southall et al. (2019b) 
observed that after exposure to simulated and operational mid-frequency 
active sonar, more than 50 percent of blue whales in deep-diving states 
responded to the sonar, while no behavioral response was observed in 
shallow-feeding blue whales. Southall et al. (2019b) noted that the 
behavioral responses they observed were generally brief, of low to 
moderate severity, and highly dependent on exposure context (behavioral 
state, source-to-whale horizontal range, and prey availability). The 
proposed survey area does not represent a major feeding area for blue 
whales and any disruption of feeding is likely to be short-term and of 
low to sometimes moderate severity, with no anticipated effect on 
reproduction or survival for individual whales or the population as a 
whole.
    Comment 7: Deep Green Wilderness and the ENGOs noted that North 
Pacific right whales have been documented within the survey area, and 
recommended NMFS consider the potential effects of the survey on the 
species. Deep Green Wilderness referred to sightings of a North Pacific 
right whale at Swiftsure Bank in 2013, and the ENGOs noted an account 
of a sighting of a North Pacific right whale off northern Vancouver 
Island in May 2020.
    Response: We thank the organizations for providing information on 
recent observations of North Pacific right whales in the survey area. 
NMFS shares the commenters' concern regarding the status of this 
endangered species. Although sightings have been reported in the survey 
area, the rate of sightings is less than one per year and NMFS has 
determined the likelihood of the proposed 37-day survey encountering a 
North Pacific right whale is discountable. However, in the very 
unlikely event a North Pacific right whale is detected during the 
survey, at any distance, L-DEO must immediately shut down the airgun 
array to prevent exposure to potentially injurious sound levels and to 
minimize the intensity and

[[Page 29096]]

duration of any sound exposure, and must immediately report the 
observation to NMFS and Canada's DFO to further inform research on the 
distribution of the species.
    Comment 8: The ENGOs challenge NMFS' preliminary finding that the 
proposed take numbers are of no more than small numbers of marine 
mammals. The ENGOs reference a court decision that they assert supports 
a lower ``small numbers'' threshold, and highlight certain species for 
which the commenters deem the take to be too high.
    Response: The reference to a supposed take limit of 12 percent for 
small numbers comes from a 2003 district court opinion (Natural 
Resources Defense Council v. Evans, 279 F. Supp. 2d 1129 (N.D. Cal. 
2003)). However, given the particular administrative record and 
circumstances in that case, including the fact that our small numbers 
finding for the challenged incidental take rule was based on an invalid 
regulatory definition of small numbers, we view the district court's 
opinion regarding 12 percent as dicta. Moreover, since that time the 
Ninth Circuit Court of Appeals has upheld a small numbers finding that 
was not based on a quantitative calculation. Center for Biological 
Diversity v. Salazar, 695 F.3d 893 (9th Cir. 2012). To maintain an 
interpretation of small numbers as a proportion of a species or stock 
that does not conflate with negligible impact, we use the following 
framework. A plain reading of ``small'' implies as corollary that there 
also could be ``medium'' or ``large'' numbers of animals from the 
species or stock taken. We therefore use a simple approach that 
establishes equal bins corresponding to small, medium, and large 
proportions of the population abundance.
    NMFS's practice for making small numbers determinations is to 
compare the number of individuals estimated and authorized to be taken 
(often using estimates of total instances of take, without regard to 
whether individuals are exposed more than once) against the best 
available abundance estimate for that species or stock. We note, 
however, that although NMFS's implementing regulations require 
applications for incidental take to include an estimate of the marine 
mammals to be taken, there is nothing in paragraphs (A) or (D) of 
section 101(a)(5) that requires NMFS to quantify or estimate numbers of 
marine mammals to be taken for purposes of evaluating whether the 
number is small. (See CBD v. Salazar.) While it can be challenging to 
predict the numbers of individual marine mammals that will be taken by 
an activity (again, many models calculate instances of take and are 
unable to account for repeated exposures of individuals), in some cases 
we are able to generate a reasonable estimate utilizing a combination 
of quantitative tools and qualitative information. When it is possible 
to predict with relative confidence the number of individual marine 
mammals of each species or stock that are likely to be taken, the small 
numbers determination should be based directly upon whether or not 
these estimates exceed one third of the stock abundance. In other 
words, consistent with past practice, when the estimated number of 
individual animals taken (which may or may not be assumed as equal to 
the total number of takes, depending on the available information) is 
up to, but not greater than, one third of the species or stock 
abundance, NMFS will determine that the numbers of marine mammals taken 
of a species or stock are small.
    Finally, regarding the species highlighted by the ENGOs with 
proposed take above 20 percent of the stock (Pacific white-sided 
dolphin, Risso's dolphin, pygmy and dwarf sperm whale, Dall's porpoise, 
harbor porpoise, northern fur seal and harbor seal), the revised take 
estimates for all of the aforementioned stocks aside from the 
California/Oregon/Washington stock of Dall's porpoise and Northern 
Oregon/Washington Coast stock of harbor porpoise represent under one-
third of the stock. The analysis of these two stocks is discussed 
further in the Small Numbers section of this notice.
    Comment 9: The ENGOs further object to NMFS' small numbers 
determination for the Southern Resident killer whale, for which NMFS 
proposed to authorize take of more than 57 percent of the stock. 
Regarding the Southern Resident killer whale take estimate, the ENGOs 
disagree with NMFS' assumption that the number of individual Southern 
Resident killer whales taken by Level B harassment will be fewer than 
the total estimated instances of take due to the historical pattern of 
Southern Resident killer whales occupying the inland waters of the 
Salish Sea during the summer months. Additionally, because they travel 
in pods, the commenters assert that there is risk of exposure of an 
entire pod to airgun blasting, and state that they are unclear whether 
such aggregation has been considered.
    Response: The ENGO's objection to NMFS' small numbers threshold was 
addressed in the previous response, but we also note here that using 
the revised survey tracklines, the authorized take of Southern Resident 
killer whales represents only 13.7 percent of the stock, which falls 
under NMFS' threshold for small numbers, even if all takes represent 
different individuals taken by Level B harassment. The authorized take 
is less than the size of any pod of Southern Residents (J, K, or L 
pods), and is more likely to represent a single matriline (typically 
two to nine killer whales; Weiss et al., 2020) exposed to the survey on 
one or two days of the survey. NMFS agrees that the seasonal 
distribution of Southern Resident killer whales in recent years has 
deviated from the historical pattern of residency within the Salish Sea 
(e.g., Shields et al., 2018), but note that our discussion of the 
distribution of Southern Resident killer whales was in the context of 
the U.S. Navy density models used to estimate take, which were created 
with the assumption that the entire population was either within the 
Salish Sea or outside the Salish Sea on the outer coast at any given 
time (U.S. Navy 2019). Southern Resident killer whales may be 
encountered during the survey along the coast, but the revised 
tracklines are expected to reduce the likelihood of whole pods being 
exposed to sound from the seismic survey by avoiding surveying in areas 
of expected high Southern Resident killer whale occurrence. 
Additionally, L-DEO is required to shut down the airgun array if killer 
whales (of any ecotype) are observed at any distance. Killer whales are 
highly visible animals, especially when traveling as large pods as the 
ENGOs suggest, and we expect PSOs will be able to detect killer whales 
at sufficient distances to implement shutdown procedures to avoid 
exposing large pods of killer whales to sounds from the survey.
    Comment 10: The ENGOs commented that NMFS must include estimated 
takes off Canada in making the small numbers determination, adding that 
since the take prohibition applies outside U.S. waters, the Service 
must make a small numbers determination that analyzes all of the 
estimated take. The commenters state that, accordingly, NMFS must 
demonstrate compliance with these standards and may not issue the 
authorization without fully analyzing and authorizing all take 
contemplated under this action. The commenters also state that it is 
unclear in the small numbers determination whether the takes in 
Canadian waters have been taken into consideration. The ENGOs also 
expressed concern that the small numbers determination was based on 1 
year of activities and did not consider

[[Page 29097]]

the potential renewal of the authorization.
    Response: NMFS has not authorized any take of marine mammals within 
the territorial waters of Canada. An estimate of take that may occur 
within Canadian territorial waters is presented in Table 11, and the 
take has been considered in our negligible impact determination as part 
of the larger implications of the survey on the marine mammal 
populations and habitat in the survey area. However, our small numbers 
analysis applies only to the take we have authorized. NMFS has made the 
necessary small numbers and negligible impact determinations for this 
authorization.
    The ENGOs appear to misunderstand the context in which a potential 
renewal IHA could be issued for this activity, as well as the 
requirements for issuing a renewal IHA. Although renewal IHAs in 
general may be issued in appropriate circumstances for up to another 
year of identical or nearly identical activities as were covered by the 
initial IHA, this context is not relevant to the proposed seismic 
survey. L-DEO would not conduct the survey as planned and then 
duplicate the survey activities in a subsequent year. Regardless, NMFS 
would not grant a renewal IHA in those circumstances. However, if the 
planned survey were unexpectedly delayed for another year, NMFS could 
consider a request for issuance of a renewal IHA. In order to do so, 
NMFS would need to review all relevant information, including the 
status of the affected species or stocks and any other pertinent 
information, such as information relevant to the small numbers 
determination. In short, potential consideration of a renewal in this 
context would necessarily be associated with the same activity 
associated with this IHA, in the event that it is not conducted during 
the period of effectiveness for this IHA, and would entail a review of 
all relevant information to ensure that the findings NMFS has made in 
support of issuance of this initial IHA remain valid.
    Comment 11: The ENGOs recommended NMFS analyze the effects of L-
DEO's use of a multi-beam echosounder (MBES) associated with the 
survey, noting that the proposed equipment (the Kongsberg Simrad E122) 
is similar to another Kongsberg system that was closely associated with 
a 2008 mass stranding of melon-headed whales in Madagascar. The ENGOs 
recommended NMFS apply its take threshold for continuous noise sources 
(120 dB) rather than its threshold for intermittent sources (160 dB) to 
the proposed system and revise its take estimates accordingly. Further, 
NMFS should not assume, for purposes of making its negligible impact 
determinations, that the severity of impacts from an airgun array 
operating concurrently with such an echosounder system would be 
equivalent to that of an airgun array operating alone.
    Response: Although it is correct that an investigation of the 
stranding event referenced by the ENGOs indicated that use of a high-
frequency mapping system (12-kilohertz (kHz) MBES) was the most 
plausible and likely initial behavioral trigger of the event (with the 
caveat that there was no unequivocal and easily identifiable single 
cause), the panel also noted several site- and situation-specific 
secondary factors that may have contributed to the avoidance responses 
that led to the eventual entrapment and mortality of the whales 
(Southall et al., 2013). Specifically, regarding survey patterns prior 
to the event and in relation to bathymetry, the vessel transited in a 
north-south direction on the shelf break parallel to the shore, 
ensonifying deep-water habitat prior to operating intermittently in a 
concentrated area offshore from the stranding site. This may have 
trapped the animals between the sound source and the shore, thus 
driving them towards the lagoon system. Shoreward-directed surface 
currents and elevated chlorophyll levels in the area preceding the 
event may also have played a role. The risk of similar events recurring 
is expected to be very low, given the extensive use of active acoustic 
systems used for scientific and navigational purposes worldwide on a 
daily basis and the lack of direct evidence of such responses 
previously reported. The only report of a stranding that may be 
associated with this type of sound source is the one reported in 
Madagascar.
    NMFS disagrees with the recommendation that the 120 dB threshold 
should be applied to estimate takes incidental to use of the MBES. 
Sound sources can be divided into broad categories based on various 
criteria or for various purposes. As discussed by Richardson et al. 
(1995), source characteristics include strength of signal amplitude, 
distribution of sound frequency and, importantly in context of these 
thresholds, variability over time. With regard to temporal properties, 
sounds are generally considered to be either continuous or transient 
(i.e., intermittent). Continuous sounds, which are produced by the 
industrial noise sources for which the 120-dB behavioral harassment 
threshold was selected, are simply those whose sound pressure level 
remains above ambient sound during the observation period (ANSI, 2005). 
Intermittent sounds are defined as sounds with interrupted levels of 
low or no sound (NIOSH, 1998). Simply put, a continuous noise source 
produces a signal that continues over time, while an intermittent 
source produces signals of relatively short duration having an obvious 
start and end with predictable patterns of bursts of sound and silent 
periods (i.e., duty cycle) (Richardson and Malme, 1993). It is this 
fundamental temporal distinction that is most important for 
categorizing sound types in terms of their potential to cause a 
behavioral response. For example, Gomez et al. (2016) found a 
significant relationship between source type and marine mammal 
behavioral response when sources were split into continuous (e.g., 
shipping, icebreaking, drilling) versus intermittent (e.g., sonar, 
seismic, explosives) types. In addition, there have been various 
studies noting differences in responses to intermittent and continuous 
sound sources for other species (e.g., Neo et al., 2014; Radford et 
al., 2016; Nichols et al., 2015).
    Sound sources may also be categorized based on their potential to 
cause physical damage to auditory structures and/or result in threshold 
shifts. In contrast to the temporal distinction discussed above, the 
most important factor for understanding the differing potential for 
these outcomes across source types is simply whether the sound is 
impulsive or not. Impulsive sounds, such as those produced by airguns, 
are defined as sounds which are typically transient, brief (<1 second 
(sec)), broadband, and consist of a high peak pressure with rapid rise 
time and rapid decay (ANSI, 1986; NIOSH, 1998). These sounds are 
generally considered to have greater potential to cause auditory injury 
and/or result in threshold shifts. Non-impulsive sounds can be 
broadband, narrowband or tonal, brief or prolonged, continuous or 
intermittent, and typically do not have the high peak pressure with 
rapid rise/decay time that impulsive sounds do (ANSI, 1995; NIOSH, 
1998). Because the selection of the 160-dB behavioral threshold was 
focused largely on airgun signals, it has historically been commonly 
referred to as the ``impulse noise'' threshold (including by NMFS). 
However, this longstanding confusion in terminology--i.e., the 
erroneous impulsive/continuous dichotomy--presents a narrow view of the 
sound sources to which the thresholds apply, and inappropriately 
implies a limitation in scope of applicability for the 160-dB 
behavioral threshold in particular.

[[Page 29098]]

    An impulsive sound is by definition intermittent; however, not all 
intermittent sounds are impulsive. Many sound sources for which it is 
generally appropriate to consider the authorization of incidental take 
are in fact either impulsive (and intermittent) (e.g., impact pile 
driving) or continuous (and non-impulsive) (e.g., vibratory pile 
driving). However, scientific sonars (such as MBESs) present a less 
common case where the sound produced is considered intermittent but 
non-impulsive. We note also the commenters' assertion that the system 
produces ``virtually continuous noise output'' in support of their 
recommendation to apply the continuous noise threshold to evaluation of 
this source. In context of marine mammal hearing, this would mean that 
the interval between signals would not be discernible to the animal, 
rendering them effectively continuous. However, echosounder signals are 
emitted in a similar fashion as odontocete echolocation click trains. 
Research indicates that marine mammals, in general, have extremely fine 
auditory temporal resolution and can detect each signal separately 
(e.g., Au et al., 1988; Dolphin et al., 1995; Supin and Popov, 1995; 
Mooney et al., 2009), especially for species with echolocation 
capabilities. Therefore, it is highly unlikely that marine mammals 
would perceive echosounder signals as being continuous.
    Given the existing paradigm--dichotomous thresholds appropriate for 
generic use in evaluating the potential for behavioral harassment 
resulting from exposure to continuous or intermittent sound sources--
the ENGOs do not adequately explain why potential harassment from an 
intermittent sound source should be evaluated using a threshold 
developed for use with continuous sound sources. Therefore, we have not 
reevaluated L-DEO's use of the MBES using the 120 dB continuous noise 
threshold.
    As discussed in the notice of proposed IHA, due to the lower source 
level of the MBES relative to the R/V Langseth's airgun array, sounds 
from the MBES are expected to be effectively subsumed by the sounds 
from the airgun array when both sources are operational. Thus, NMFS has 
determined that any marine mammal potentially exposed to sounds from 
the MBES would already have been exposed to sounds from the airgun 
array, which are expected to propagate further in the water, when both 
sources are operational. NMFS has determined that, given the movement 
and speed of the vessel and the intermittent and narrow downward-
directed nature of the sounds emitted by the MBES (each ping emitted by 
the MBES consists of eight (in water >1,000 m deep) or four (<1,000 m) 
successive fan-shaped transmissions, each ensonifying a sector that 
extends 1[deg] fore-aft), the MBES would result in no more than one or 
two brief ping exposures to any individual marine mammal, if any 
exposure were to occur. The ENGOs do not offer any evidence in support 
of their contention that potentially greater impacts than we have 
considered should be assumed likely in relation to use of this source.
    Comment 12: The ENGOs comment that NMFS has failed to implement 
``means of effecting the least practicable impact'' on marine mammals 
and assert that NMFS relies on mitigation measures that are known to be 
ineffective (e.g., real-time detection-based measures).
    Response: Under section 101(a)(5)(D) of the MMPA, NMFS must set 
forth the permissible methods of taking by harassment pursuant to such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for subsistence 
uses (hereinafter referred to as least practicable adverse impact). 
NMFS does not have a regulatory definition for least practicable 
adverse impact.
    NMFS disagrees with the assertion that we have failed to meet the 
least practicable adverse impact standard in this case. NMFS considered 
all recommended mitigation in the context of both the reduction of 
impacts on marine mammal species and stocks and their habitat and the 
practicability of such mitigation in reaching the required set of 
measures that we believe satisfy the least practicable adverse impact 
standard.
    NMFS' evaluation of potential mitigation measures includes 
consideration of two primary factors:
    (1) The manner in which, and the degree to which, implementation of 
the potential measure(s) is expected to reduce adverse impacts to 
marine mammal species or stocks, their habitat, and their availability 
for subsistence uses (where relevant). This analysis considers such 
things as the nature of the potential adverse impact (such as 
likelihood, scope, and range), the likelihood that the measure will be 
effective if implemented, and the likelihood of successful 
implementation.
    (2) The practicability of the measures for applicant 
implementation. Practicability of implementation may consider such 
things as cost, impact on activities, personnel safety, and 
practicality of implementation.
    While the language of the least practicable adverse impact standard 
calls for minimizing impacts to affected species or stocks and their 
habitat, NMFS recognizes that the reduction of impacts to those species 
or stocks accrues through the application of mitigation measures that 
limit impacts to individual animals. Accordingly, NMFS' analysis 
focuses on measures that are designed to avoid or minimize impacts on 
individual marine mammals that are likely to increase the probability 
or severity of population-level effects.
    While direct evidence of impacts to species or stocks from a 
specified activity is rarely available, and additional study is still 
needed to understand how specific disturbance events affect the fitness 
of individuals of certain species, there have been improvements in 
understanding the process by which disturbance effects are translated 
to the population. With recent scientific advancements (both marine 
mammal energetic research and the development of energetic frameworks), 
the relative likelihood or degree of impacts on species or stocks may 
often be inferred given a detailed understanding of the activity, the 
environment, and the affected species or stocks. This same information 
is used in the development of mitigation measures and helps us 
understand how mitigation measures contribute to lessening effects (or 
the risk thereof) to species or stocks. NMFS also acknowledges that 
there is always the potential that new information, or a new 
recommendation that had not previously been considered, becomes 
available and necessitates re-evaluation of mitigation measures to see 
if further reductions of population impacts are possible and 
practicable.
    In the evaluation of specific measures, the details of the 
specified activity will necessarily inform each of the two primary 
factors discussed above (expected reduction of impacts and 
practicability) and are carefully considered to determine the types of 
mitigation that are appropriate under the least practicable adverse 
impact standard. Analysis of how a potential mitigation measure may 
reduce adverse impacts on a marine mammal stock or species and 
practicability of implementation are not issues that can be 
meaningfully evaluated through a yes/no lens. The manner in which, and 
the degree to which, implementation of a measure is expected to reduce 
impacts, as well as its practicability, can

[[Page 29099]]

vary widely. For example, a time-area restriction could be of very high 
value for reducing the potential for, or severity of, population-level 
impacts (e.g., avoiding disturbance of feeding females in an area of 
established biological importance) or it could be of lower value (e.g., 
decreased disturbance in an area of high productivity but of less 
firmly established biological importance). Regarding practicability, a 
measure might involve restrictions in an area or time that impede the 
operator's ability to acquire necessary data (higher impact), or it 
could mean incremental delays that increase operational costs but still 
allow the activity to be conducted (lower impact). A responsible 
evaluation of ``least practicable adverse impact'' will consider the 
factors along these realistic scales. Expected effects of the activity 
and of the mitigation as well as status of the stock all weigh into 
these considerations. Accordingly, the greater the likelihood that a 
measure will contribute to reducing the probability or severity of 
adverse impacts to the species or stock or their habitat, the greater 
the weight that measure is given when considered in combination with 
practicability to determine the appropriateness of the mitigation 
measure, and vice versa. Consideration of these factors is discussed in 
greater detail below.
1. Reduction of Adverse Impacts to Marine Mammal Species or Stocks and 
Their Habitat
    The emphasis given to a measure's ability to reduce the impacts on 
a species or stock considers the degree, likelihood, and context of the 
anticipated reduction of impacts to individuals (and how many 
individuals) as well as the status of the species or stock.
    The ultimate impact on any individual from a disturbance event 
(which informs the likelihood of adverse species- or stock-level 
effects) is dependent on the circumstances and associated contextual 
factors, such as duration of exposure to stressors. Though any proposed 
mitigation needs to be evaluated in the context of the specific 
activity and the species or stocks affected, measures with the 
following types of effects have greater value in reducing the 
likelihood or severity of adverse species- or stock-level impacts: 
Avoiding or minimizing injury or mortality; limiting interruption of 
known feeding, breeding, mother/young, or resting behaviors; minimizing 
the abandonment of important habitat (temporally and spatially); 
minimizing the number of individuals subjected to these types of 
disruptions; and limiting degradation of habitat. Mitigating these 
types of effects is intended to reduce the likelihood that the activity 
will result in energetic or other types of impacts that are more likely 
to result in reduced reproductive success or survivorship. It is also 
important to consider the degree of impacts that are expected in the 
absence of mitigation in order to assess the added value of any 
potential measures. Finally, because the least practicable adverse 
impact standard gives NMFS discretion to weigh a variety of factors 
when determining appropriate mitigation measures and because the focus 
of the standard is on reducing impacts at the species or stock level, 
the least practicable adverse impact standard does not compel 
mitigation for every kind of take, or every individual taken, if that 
mitigation is unlikely to meaningfully contribute to the reduction of 
adverse impacts on the species or stock and its habitat, even when 
practicable for implementation by the applicant.
    The status of the species or stock is also relevant in evaluating 
the appropriateness of potential mitigation measures in the context of 
least practicable adverse impact. The following are examples of factors 
that may (either alone, or in combination) result in greater emphasis 
on the importance of a mitigation measure in reducing impacts on a 
species or stock: The stock is known to be decreasing or status is 
unknown, but believed to be declining; the known annual mortality (from 
any source) is approaching or exceeding the PBR level; the affected 
species or stock is a small, resident population; or the stock is 
involved in a UME or has other known vulnerabilities, such as 
recovering from an oil spill.
    Habitat mitigation, particularly as it relates to rookeries, mating 
grounds, and areas of similar significance, is also relevant to 
achieving the standard and can include measures such as reducing 
impacts of the activity on known prey utilized in the activity area or 
reducing impacts on physical habitat. As with species- or stock-related 
mitigation, the emphasis given to a measure's ability to reduce impacts 
on a species or stock's habitat considers the degree, likelihood, and 
context of the anticipated reduction of impacts to habitat. Because 
habitat value is informed by marine mammal presence and use, in some 
cases there may be overlap in measures for the species or stock and for 
use of habitat.
    NMFS considers available information indicating the likelihood of 
any measure to accomplish its objective. If evidence shows that a 
measure has not typically been effective nor successful, then either 
that measure should be modified or the potential value of the measure 
to reduce effects should be lowered.
2. Practicability
    Factors considered may include those costs, impact on activities, 
personnel safety, and practicality of implementation.
    In carrying out the MMPA's mandate for this action, NMFS applies 
the previously described context-specific balance between the manner in 
which and the degree to which measures are expected to reduce impacts 
to the affected species or stocks and their habitat and practicability 
for operators. The effects of concern (i.e., those with the potential 
to adversely impact species or stocks and their habitat), addressed 
previously in the Potential Effects of the Specified Activity on Marine 
Mammals and Their Habitat section of the notice of proposed IHA, 
include auditory injury, severe behavioral reactions, disruptions of 
critical behaviors, and to a lesser degree, masking and impacts on 
acoustic habitat. Here, we focus on measures with proven or reasonably 
presumed ability to avoid or reduce the intensity of acute exposures 
that have potential to result in these anticipated effects with an 
understanding of the drawbacks or costs of these requirements, as well 
as time-area restrictions that would avoid or reduce both acute and 
chronic impacts. To the extent of the information available to NMFS, we 
considered practicability concerns, as well as potential undesired 
consequences of the measures, e.g., extended periods using the acoustic 
source due to the need to reshoot lines. NMFS also recognizes that 
instantaneous protocols, such as shutdown requirements, are not capable 
of avoiding all acute effects, and are not suitable for avoiding many 
cumulative or chronic effects and do not provide targeted protection in 
areas of greatest importance for marine mammals. Therefore, in addition 
to a basic suite of seismic mitigation protocols, we also consider 
measures that may or may not be appropriate for other activities (e.g., 
survey plan modifications specific to the action discussed herein), but 
that are warranted here given the potential for impacts to a stock of 
particular concern (i.e., Southern Resident killer whales) (see 
Negligible Impact Analysis and Determination), and the information we 
have regarding habitat for certain species.
    We appreciate the ENGOs suggestions for additional mitigation and 
monitoring

[[Page 29100]]

requirements. However, we note that many of the recommendations require 
a scale of effort that is not commensurate to the scale of either the 
underlying activities or the anticipated impacts of the activities on 
marine mammals covered by this authorization. In other words, many of 
the recommended measures would necessitate complex and expensive survey 
designs and methods that are not reasonable in the context of an 
activity that consists of one mobile source moving across a large area 
and that will last for only 37 days. As described in the Mitigation 
Measures Considered but Eliminated section of this notice, out of 
concern for the status of Southern Resident killer whales and proposed 
critical habitat, NMFS considered implementing a closure area and 
prohibiting L-DEO from conducting survey operations between the 200-m 
isobath and the coastline. However, as the main goal of L-DEO's survey 
is to examine the geologic features of the Cascadia subduction zone 
along the coastal shelf, NMFS determined that this exclusion would not 
be practicable. NMFS did ultimately incorporate mitigation measures 
that are specific to this action and beyond that which is typically 
required for L-DEO's surveys. Specifically, we have required L-DEO to 
revise their proposed tracklines to avoid surveying in waters less than 
100 m deep in areas with highest estimated Southern Resident killer 
whale occurrence. We have determined this measure, which will 
significantly reduce impacts to Southern Resident killer whales while 
allowing L-DEO to complete its survey objectives, to be practicable. 
Additionally, L-DEO must use a second vessel traveling ahead of the R/V 
Langseth with additional PSOs to increase the likelihood of detecting 
Southern Resident killer whales and, therefore, allowing for greater 
efficacy in implementing shutdown procedures to minimize impacts to 
animals that may be in the area. Regardless of whether other monitoring 
plans suggested by the ENGOs would also suffice, NMFS has determined 
that the mitigation and monitoring required as part of this 
authorization meets the MMPA requirement for least practicable adverse 
impact.
    Comment 13: The ENGOs suggested NMFS should work with L-DEO and 
explore ways to conduct the survey without ensonifying designated and 
proposed Southern Resident killer whale critical habitat, or at 
minimum, prohibit ramp-up in the proposed and designated critical 
habitat unless the location of all three pods of Southern Resident 
killer whales is known to be within the Salish Sea or in an area not 
impacted by survey activity on each day of the survey.
    Response: As discussed above, NMFS considered prohibiting L-DEO 
from operating within the proposed critical habitat for Southern 
Resident killer whales, but determined that the exclusion was not 
practicable, as it would prevent L-DEO from completing their survey 
objectives. NMFS has worked with L-DEO to revise the survey tracklines 
to avoid ensonifying waters less than 100 m deep above the Level B 
harassment threshold, between Tillamook Head, Oregon and Barkley Sound, 
British Columbia. As stated above, this area contains the highest 
estimated density of Southern Resident killer whales. NMFS has not 
required L-DEO to confirm the location of Southern Resident killer 
whales before beginning survey activities each day as the location of 
all three pods is often unknown and waiting for confirmation would not 
allow L-DEO to complete their research objectives. L-DEO is required to 
contact several entities (including NMFS, Canada's DFO, Orca Network, 
and the Whale Museum) on each day of the survey to obtain any recent 
reports of Southern Resident killer whales in the survey area.
    Comment 14: The ENGOs suggested NMFS should consider closures or 
limits on survey activity in proposed humpback whale critical habitat 
and biologically important areas for blue whales.
    Response: The revised tracklines mentioned above, while primarily 
intended to avoid areas of highest Southern Resident killer whale 
occurrence, also reduce survey tracklines in recently finalized 
humpback whale critical habitat (86 FR 21082; April 21, 2021) and BIAs 
for humpback whales and other marine mammals (we note that no BIAs for 
blue whales have been identified in the survey area). Eliminating all 
tracklines in humpback whale critical habitat would prevent L-DEO from 
completing their research objectives, as the proposed critical habitat 
occupies most of the continental shelf area off of the west coast of 
the U.S., the key area for L-DEO's research. Additionally, the ENGOs do 
not provide any substantive reasoning for why prohibiting L-DEO from 
operating within humpback whale critical habitat or BIAs is warranted. 
As discussed in the Negligible Impact Analysis and Determination 
section of this notice, L-DEO's activity is not expected to have a 
lasting physical impact on humpback whale critical habitat, prey within 
it, or overall humpback whale fitness.
    Comment 15: In addition to vessel-based passive acoustic monitoring 
(PAM), the ENGOs suggested NMFS should require the use of existing 
moored passive acoustic monitoring systems and installation of 
temporary hydrophones or sonabuoys in the survey area to monitor marine 
mammal presence.
    Response: NMFS appreciates the suggestions regarding increasing 
acoustic monitoring. However, the existing network of acoustic 
recorders along the Washington coast is comprised of archival 
recorders, which are not monitored in real-time. While the deployment 
of temporary hydrophones and sonabuoys in the survey area may aid in 
detection and monitoring of marine mammals, NMFS does not expect that 
any additional protection would outweigh the cost and practicability 
concerns associated with additional personnel required to monitor the 
systems and relay detections to the research vessel. The use of on-
board PAM will adequately alert L-DEO of vocalizing marine mammals in 
the immediate vicinity of the survey activity.
    Comment 16: The ENGOs recommended NMFS should require the use of a 
support vessel traveling ahead of the R/V Langseth in proposed critical 
habitat for humpback whales and biologically important areas (BIAs) for 
other cetaceans.
    Response: The support vessel referenced by the ENGOs is required to 
travel approximately 5 km ahead of the R/V Langseth while surveying in 
waters 200 m or less between Tillamook Head, Oregon and Barkley Sound, 
British Columbia (see Mitigation section of this notice). This area 
encompasses much of the critical habitat for humpback whales and 
biologically important areas for other species (e.g., gray whale BIA 
for migration). The area of the humpback whale critical habitat 
expected to be surveyed on a given day is only a small portion of the 
overall critical habitat along the coast. Any impacts to marine mammals 
in this area are expected to be minor and temporary, and any additional 
protection that may be provided by requiring L-DEO to use the support 
vessel outside of the 200-m isobath is not warranted in the context of 
the expected effects and practicability concerns.
    Comment 17: The ENGOs suggested NMFS should prohibit survey 
activity in low-visibility conditions.
    Response: NMFS disagrees that survey activity should be prohibited 
in low-visibility conditions. Any requirement to cease operations 
during low visibility conditions, including at

[[Page 29101]]

night, would not only be impracticable, it would also likely result in 
greater impacts to marine mammals, as such a measure would require 
operations to continue for significantly more time, to make up for lost 
operations during low-visibility times. Ramp-up of the acoustic source, 
when necessary, may occur at times of poor visibility (including 
nighttime), assuming that a pre-clearance period has been observed. If 
the pre-clearance period occurs at nighttime, the pre-clearance watch 
would be conducted only by the acoustic observer.
    Comment 18: The ENGOs suggested NMFS should consider whether aerial 
observations would have less impact (than the support vessel).
    Response: Similar to the suggestion of deploying additional PAM 
systems above, NMFS has determined it is not practicable to require L-
DEO to use aerial monitoring systems. NMFS does not expect that any 
additional protection would outweigh the cost and practicability of 
additional personnel required to monitor the systems and relay 
detections to the research vessel.
    Comment 19: The ENGOs suggested the 1,500-meter exclusion zone, 
which is required for beaked whales, should apply for other marine 
mammal species that they suggest are particularly sensitive -- such as 
harbor porpoises, Steller sea lions, baleen whales (except gray whales) 
and Southern Resident killer whales. The commenters suggest that the 
presence of Southern Residents should trigger a shut-down whenever they 
are detected, regardless of distance.
    Response: NMFS disagrees that a larger standard exclusion zone is 
warranted for the species and groups suggested by the ENGOs. The 
standard exclusion zone for all marine mammals included in the IHA is 
500 m, with larger exclusion zones or shutdown requirements for certain 
species and/or scenarios. NMFS' intent in prescribing a standard 
exclusion zone distance is to (1) encompass zones for most species 
within which auditory injury could occur on the basis of instantaneous 
exposure; (2) provide additional protection from the potential for more 
severe behavioral reactions (e.g., panic, antipredator response) for 
marine mammals at relatively close range to the acoustic source; (3) 
provide consistency and ease of implementation for protected species 
observers (PSOs), who need to monitor and implement the exclusion zone; 
and (4) define a distance within which detection probabilities are 
reasonably high for most species under typical conditions. The use of 
500 m as the zone is not based directly on any quantitative 
understanding of the range at which auditory injury would be entirely 
precluded or any range specifically related to disruption of behavioral 
patterns. Rather, NMFS believes it is based on a reasonable combination 
of factors. In summary, a practicable criterion such as this has the 
advantage of familiarity and simplicity while still providing in most 
cases a zone larger than relevant auditory injury zones, given 
realistic movement of source and receiver. Increased shutdowns, without 
a firm idea of the outcome the measure seeks to avoid, simply displace 
survey activity in time and increase the total duration of acoustic 
influence as well as total sound energy in the water, which NMFS seeks 
to avoid. In keeping with the four broad goals outlined above, and in 
context of the information given here, the standard 500-m exclusion 
zone is appropriate. The ENGOs do not provide any substantive reasoning 
for a larger zone.
    The proposed IHA included the requirement to shut down the airgun 
array if killer whales (of any ecotype) are visually or acoustically 
detected at any distance and NMFS has retained this requirement in the 
final authorization.
    Comment 20: The ENGOs suggested NMFS should require L-DEO to use 
the lowest practicable source level for airgun usage.
    Response: L-DEO has selected the equipment necessary to achieve 
their research objectives. We have evaluated the specified activity as 
defined by the applicant, including changes agreed-upon with NMFS in 
order to provide additional protection for Southern Resident killer 
whales, and made the necessary findings to authorize taking of marine 
mammals incidental to L-DEO's survey activities. We also note that an 
expert panel was convened by the Bureau of Ocean Energy Management to 
determine whether it would be feasible to develop standards to 
determine a lowest practicable source level. The panel determined that 
it would not be reasonable or practicable to develop such metrics (see 
Appendix L in BOEM, 2017).
    Comment 21: The ENGOs suggested NMFS should require in situ sound 
source verification to determine accurate exclusion zones. Similarly, 
the Commission recommended NMFS require L-DEO analyze the data recorded 
on the OBSs and OBNs to determine the extents of the Level B harassment 
zones in shallow-, intermediate-, and deep-water depths and specify how 
the in-situ zones compare to the Level B harassment zones specified in 
the final authorization.
    Response: As stated above, the exclusion zones are not necessarily 
based on specific acoustic parameters, thus sound source verification 
is not necessary in the context of exclusion zones. Regarding the 
Commission's recommendation to conduct analysis of OBS data, L-DEO has 
not previously undertaken the type of analysis suggested by the 
Commission, and indicated to NMFS that it does not have the expertise 
or capability to do so at this time. In addition, we note that the 
Commission's recommendation is vague; detailed direction would be 
needed from the Commission on how to accomplish the recommended effort. 
This would need to include agreement on the analytical approach in 
order to meet expectations and to ensure acceptance of results. The 
Commission's recommendation does not acknowledge the time it would take 
to perform the analysis or the level of effort and cost that would be 
involved, e.g., experts needed to obtain and review data, performing 
detailed comparative analysis, preparation of a report. Based on these 
concerns, NMFS believes that the recommendation is not practicable.
    Also, implementation of this recommendation would not provide any 
additional conservation value (e.g., improvement in mitigation 
effectiveness) for the proposed survey. The analysis would be 
retrospective and could be used to help inform analysis of future 
surveys in the same area. NSF is considering funding a survey of the 
Queen Charlotte Fault, north of the planned survey area for this 
action, but the survey would be completed before the acoustic data from 
this survey suggested by the Commission could be analyzed. NMFS is not 
aware of any other NSF-proposed seismic surveys on the R/V Langseth for 
this region in the foreseeable future that could incorporate the in 
situ data, if analyzed.
    Comment 22: The ENGOs suggested NMFS should prohibit the use of the 
Kongsberg Simrad 122 MBES in shallow water because the system's lower 
frequencies were designed for use in deeper water.
    Response: The ENGOs provide no justification for prohibiting the 
use of the MBES in shallow water aside from describing its 
characteristics. As discussed in previous comment responses, NMFS has 
determined the MBES is not likely to result in take of marine mammals 
and has no reason to believe that the use of the Kongsberg Simrad 122 
in shallow water is cause for concern. The ENGOs do not provide any 
substantive argument to the contrary.

[[Page 29102]]

    Comment 23: The ENGOs suggested NMFS should require L-DEO to 
immediately cease survey activities if any authorized take limits are 
exceeded or if a take of an unauthorized species occurs (e.g., take of 
a North Pacific right whale).
    Response: NMFS agrees with the ENGOs that L-DEO must shut down the 
airgun array 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. This requirement was included in the notice of proposed IHA but 
was inadvertently omitted from the draft IHA. The final authorization 
includes this requirement.
    Comment 24: The ENGOs suggested NMFS should require L-DEO to 
immediately cease survey activities if a take of an unauthorized level 
or intensity occurs, (e.g., serious injury or mortality of any species 
or take of a Southern Resident killer whale by Level A harassment). The 
ENGOs further suggest that if take is found to have been exceeded, then 
there should be an investigation and additional mitigation to avoid any 
additional take before activities can resume. Similarly, the Commission 
recommended NMFS include in all draft and final authorizations an 
explicit requirement to cease activities if a marine mammal is injured 
or killed during the specified activities, including by vessel strike, 
until NMFS reviews the circumstances involving any injury or death that 
is likely attributable to the activities and determines what additional 
measures are necessary to minimize additional injuries or death.
    Response: NMFS does not expect that the proposed activities have 
the potential to result in injury or mortality to marine mammals and 
therefore does not agree that a blanket requirement for project 
activities to cease would be warranted. NMFS does not agree that a 
requirement for a vessel that is operating on the open water to 
suddenly stop operating is practicable, and it is unclear what 
mitigation benefit would result from such a requirement in relation to 
vessel strike. The Commission does not suggest what measures other than 
those prescribed in this IHA would potentially prove more effective in 
reducing the risk of strike. Therefore, we have not included this 
requirement in the authorization. NMFS retains authority to modify the 
IHA and cease all activities immediately based on a vessel strike and 
will exercise that authority if warranted.
    With respect to the Commission's recommendation that NMFS include 
these requirements in all proposed and final IHAs, NMFS determines the 
requirements for mitigation measures in each authorization based on 
numerous case-specific factors, including 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. As NMFS must 
make these determinations on a case by case basis, we therefore do not 
agree with this recommendation.
    Comment 25: The ENGOs suggested NMFS impose a ship speed limit of 
10 knots or less at all times to reduce noise and prevent ship strikes, 
with an exception for rare emergency or safety necessities. While the 
vessel conducting the survey is likely to be traveling well under 10 
knots, NMFS should make this a requirement of any crew-transfer vessels 
used in the project.
    Response: NMFS has analyzed the potential for ship strike resulting 
from L-DEO's planned activity and has determined that the mitigation 
measures specific to ship strike avoidance are sufficient to avoid the 
potential for ship strike. These include: A requirement that all vessel 
operators reduce vessel speed to 10 knots (18.5 km/hour) or less when 
any large whale, any mother/calf pairs, pods, or large assemblages of 
non-delphinoid cetaceans are observed within 100 m of an underway 
vessel; a requirement that all survey vessels maintain a separation 
distance of 100 m or greater from all large whales, and 500 m or 
greater from any sighted North Pacific right whale (if a whale is 
observed but cannot be confirmed as a species other than a right whale, 
the vessel operator must assume that it is a right whale and take 
appropriate action); a requirement that if protected species are 
sighted while a vessel is underway, the vessel must take action as 
necessary to avoid violating the relevant separation distance (e.g., 
attempt to remain parallel to the animal's course, avoid excessive 
speed or abrupt changes in direction until the animal has left the 
area); and a requirement that if marine mammals are sighted within the 
relevant separation distance, the vessel must reduce speed and shift 
the engine to neutral, not engaging the engines until animals are clear 
of the area. Finally, we note that all crew will be aboard the R/V 
Langseth through the entire survey, and there will not be any crew 
transfer vessels. We have determined that the ship strike avoidance 
measures are sufficient to ensure the least practicable adverse impact 
on species or stocks and their habitat and therefore we do not include 
the 10 knot ship speed limit recommended by the ENGOs.
    Comment 26: The ENGOs recommended NMFS require L-DEO to minimize 
the use of lines and cables and ensure that they are not flexible to 
reduce entanglement risk.
    Response: As discussed in the notice of proposed IHA, no incidents 
of entanglement of marine mammals with seismic survey gear have been 
documented in over 54,000 nautical miles (nmi; 100,000 km) of previous 
NSF-funded seismic surveys when observers were aboard (e.g., Holst and 
Smultea 2008; RPS 2019; RPS 2021). 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 therefore although we encourage L-DEO 
to use lines and cables that minimize entanglement risk, NMFS has not 
included the recommended requirement as a condition in the final 
authorization.
    Comment 27: The ENGOs state that marine mammal strandings are most 
likely to result when a sound source is moving directly toward the 
shore. Therefore, the ENGOs suggested NMFS should require reconfigured 
tracklines to avoid these approaches when the airguns are firing.
    Response: There is no conclusive evidence that exposure to airgun 
noise results in behaviorally-mediated forms of injury (i.e., mass 
stranding events). Behaviorally-mediated injury has been primarily 
associated with beaked whales exposed to mid-frequency active (MFA) 
naval sonar. As described in the notice of proposed IHA, tactical sonar 
is very different from the noise produced by airguns. One should 
therefore not expect the same reaction to airgun noise as to these 
other sources. The ENGOs reference a survey conducted by L-DEO in 2002 
that was contemporaneous with and reasonably associated spatially with 
the stranding of two Cuvier's beaked whales. However, the event was not 
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

[[Page 29103]]

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. Although NMFS does not 
expect that stranding is a potential outcome of this survey activity, 
we also note that certain tracklines closest to shore (i.e., in waters 
less than 100 m deep in areas with highest estimated Southern Resident 
killer whale occurrence) have been eliminated, further reducing the 
risk of this outcome. 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. Therefore, we have not adopted the ENGOs recommendation to 
reconfigure the survey tracklines.
    Comment 28: Both the ENGOs and Commission object to NMFS' potential 
consideration of a renewal IHA for this action, and in general. The 
ENGOs assert that IHA renewals are not permissible under the MMPA and 
instead recommend that applicants request a multi-year permit and 
accordingly reevaluate the effects of the action based on multiple 
years of take. The Commission recommended NMFS refrain from issuing IHA 
renewals for any authorization and instead use an abbreviated Federal 
Register notice process, which is similarly expeditious and fulfills 
NMFS' intent to maximize efficiencies. If NMFS continues to propose to 
issue IHA renewals, the Commission recommends that NMFS (1) stipulate 
that a renewal is a one-time opportunity (a) in all Federal Register 
notices requesting comments on the possibility of a renewal, (b) on its 
web page detailing the renewal process, and (c) in all draft and final 
authorizations that include a term and condition for a renewal and (2) 
if NMFS declines to adopt this recommendation, explain fully its 
rationale for not doing so.
    Response: NMFS' IHA renewal process meets all statutory 
requirements. All IHAs issued, whether an initial IHA or a renewal IHA, 
are valid for a period of not more than one year. In addition, the 
public has at least 30 days to comment on all proposed IHAs, with a 
cumulative total of 45 days for IHA renewals. As noted above, the 
Request for Public Comments section of the notice of proposed IHA made 
clear that the agency was seeking comment on both the initial proposed 
IHA and the potential issuance of a renewal for this project. Because 
any renewal (as explained in the Request for Public Comments section of 
the notice of proposed IHA) is limited to another year of identical or 
nearly identical activities in the same location (as described in the 
Description of Proposed Activity section) or the same activities that 
were not completed within the 1 year period of the initial IHA, 
reviewers have the information needed to effectively comment on both 
the immediate proposed IHA and a possible 1 year renewal, should the 
IHA holder choose to request one in the coming months.
    While there will be additional documents submitted with a renewal 
request, for a qualifying renewal these will be limited to 
documentation that NMFS will make available and use to verify that the 
activities are identical to those in the initial IHA, are nearly 
identical such that the changes would have either no effect on impacts 
to marine mammals or decrease those impacts, or are a subset of 
activities already analyzed and authorized but not completed under the 
initial IHA. NMFS will also confirm, among other things, that the 
activities will occur in the same location; involve the same species 
and stocks; provide for continuation of the same mitigation, 
monitoring, and reporting requirements; and that no new information has 
been received that would alter the prior analysis. The renewal request 
will also contain a preliminary monitoring report, but that is to 
verify that effects from the activities do not indicate impacts of a 
scale or nature not previously analyzed. The additional 15-day public 
comment period provides the public an opportunity to review these few 
documents, provide any additional pertinent information and comment on 
whether they think the criteria for a renewal have been met. Between 
the initial 30-day comment period on these same activities and the 
additional 15 days, the total comment period for a renewal is 45 days.
    In addition to the IHA renewal process being consistent with all 
requirements under section 101(a)(5)(D), it is also consistent with 
Congress' intent for issuance of IHAs to the extent reflected in 
statements in the legislative history of the MMPA. Through the 
provision for renewals in the regulations, description of the process 
and express invitation to comment on specific potential renewals in the 
Request for Public Comments section of each proposed IHA, the 
description of the process on NMFS' website, further elaboration on the 
process through responses to comments such as these, posting of 
substantive documents on the agency's website, and provision of 30 or 
45 days for public review and comment on all proposed initial IHAs and 
renewals respectively, NMFS has ensured that the public ``is invited 
and encouraged to participate fully in the agency decision-making 
process.''
    NMFS does not agree with the Commission and therefore does not 
adopt the Commission's recommendation that NMFS use an abbreviated 
Federal Register notice instead of IHA renewal. NMFS has previously 
provided responses to this specific recommendation in multiple notices, 
including 84 FR 52464 (October 2, 2019). NMFS does agree with the 
Commission's recommendation that NMFS specify that IHA renewals are a 
one-time opportunity in all Federal Register notices requesting 
comments on the possibility of an IHA renewal, in all associated 
proposed and final IHAs, and on our website. NMFS has specified this in 
the final IHA for L-DEO's activities and has been including this in 
Federal Register notices and proposed and final authorizations since 
last year.
    Comment 29: The ENGOs recommended NMFS and L-DEO explore whether 
the proposed research could be conducted using alternative technologies 
or approaches that are less harmful to marine mammals. More broadly, 
and beyond the scope of this action, the ENGOs recommended NMFS engage 
with NSF to invest in research that explores alternative technologies.
    Response: NMFS agrees with the ENGOs that development and use of 
technologies that reduce the environmental impact of geophysical 
surveys is a laudable objective and may be warranted in some cases. 
Alternative technologies are in various stages of development, and none 
of the systems with the potential to replace airguns as a seismic 
source are currently commercially available for use on a scale of 
activity such as that considered herein. Although some alternative 
technologies are available now, or will be in the next several years, 
for select uses, none are at a stage where they can replace airgun 
arrays outright. However, some may be used in select environments when 
commercially available. Such technologies may be evaluated in the 
future as they become commercially available and on a scale 
commensurate to the need. In summary, while we agree that alternative 
technologies may be beneficial, the ENGOs do not suggest any specific 
technologies or approaches and the suggestion that NMFS engage with NSF 
to research these methods is outside the authority provided to NMFS by 
the MMPA. However, NMFS would consider participating in related efforts

[[Page 29104]]

by the ENGOs or other entities interested in these technologies.
    Comment 30: The ENGOs and the Commission recommended NMFS require 
L-DEO to use the method proposed by the Commission to estimate take and 
apply relevant corrections for airgun activity in daylight vs nighttime 
(including dawn and dusk) to better estimate the numbers of marine 
mammals taken by Level A and B harassment. The Commission further 
recommends that NMFS require L-DEO to specify in the final monitoring 
report (1) the number of days on which the airgun array was active and 
(2) the percentage of time and total time the array was active during 
daylight vs nighttime hours (including dawn and dusk).
    Response: NMFS appreciates the Commission's development of a 
recommended approach to better estimate the numbers of marine mammals 
that may have been taken during geophysical survey activities, 
including marine mammals that were not detected. The ``Commission's 
method'' (see the Commission's letter for additional discussion and 
citation to a full description provided in an addendum to a May 1, 2019 
Commission comment letter) involves correction of marine mammal 
sightings data through use of proxies for marine mammal detectability 
(f (0)) and platform/observer bias on marine mammal detection (g (0)), 
and extrapolation of corrected marine mammal sightings data based on 
the assumed extent of the Level B harassment zones.
    However, NMFS does not concur with the recommendation to require L-
DEO to implement this approach because we do not have confidence in the 
reliability of estimates of potential marine mammal take that would 
result from use of the approach. The Commission does not address the 
multiple assumptions that must be made in order to have confidence in 
the estimates that would be produced through application of the method. 
For example, the assumption that the application of proxy values for g 
(0) and f (0) is appropriate is not justified (including application of 
f (0) values to species for which no value is available and assuming 
that application of f (0) to species in a wholly different region is 
appropriate). Notably, g (0) values are typically derived on a 
platform-specific basis, and even for specific observers--not 
generalized across platforms, as the Commission's method would require.
    Separately, the appropriate application of distance sampling 
methods requires that certain assumptions are valid, and the Commission 
does not explain why these assumptions should be assumed to be valid 
during a seismic survey, as compared with typical line-transect surveys 
operating without an active acoustic source. For example, a key 
underlying concept of distance sampling methodology is that the 
probability of detecting an animal decreases as its distance from the 
observer increases. This cannot be assumed true during an active 
seismic survey. NMFS believes it unlikely that the numerous assumptions 
inherent to application of the Commission's method would be accepted in 
a research context (where distance sampling approaches are typically 
applied).
    Furthermore, the area over which observations are to be 
extrapolated through the Commission's method is a modeled ensonified 
area. We do not believe it appropriate to assume a modeled ensonified 
area is always accurate for purposes of estimating total take. In 
purporting to estimate total takes, the method ignores the fact that 
marine mammals exposed to a level of received sound assumed to cause 
take for analytical purposes may not in fact respond behaviorally in a 
way that equates to take, especially at great distance from the source.
    NMFS believes it is important to focus on collection and reporting 
of empirical data that can directly inform an assessment of the effects 
of a specified activity on the affected species or stock. While there 
may be value in an assessment of potential unobserved take, we need to 
proceed cautiously in the development of derived values given our low 
confidence in multiple inputs. NMFS is currently more broadly 
evaluating monitoring requirements, including data collection, 
interpretation, and reporting, as well as the specific issue the 
Commission has raised, and is committed to developing improved 
approaches.
    NMFS does concur with the Commission's recommendation that NMFS 
require L-DEO to specify in the final monitoring report (1) the number 
of days on which the airgun array was active and (2) the percentage of 
time and total time the array was active during daylight vs nighttime 
hours (including dawn and dusk). This requirement has been added to the 
final authorization.
    Comment 31: The Commission asserts that L-DEO and other NSF-
affiliated entities have not complied with all of the requirements set 
forth in certain final IHAs, and recommends that, should the alleged 
shortcomings occur again, NMFS refrain from issuing any further 
authorizations to L-DEO and other NSF-affiliated entities until such 
time that the monitoring reports include all of the required 
information.
    Response: NMFS appreciates the Commission's concern and will 
consider any future requests for incidental take authorization from 
NSF-affiliated entities according to the requirements of the MMPA.
    Comment 32: Noting its disagreement with L-DEO's approach to 
estimating the size of various ensonified areas, the Commission 
recommends that NMFS require L-DEO to either (1) re-estimate the 
proposed Level A and B harassment zones and associated takes of marine 
mammals using (a) both operational and site-specific environmental 
parameters, (b) what the Commission believes to be a comprehensive 
source model and (c) what the Commission believes to be an appropriate 
sound propagation model for the proposed IHA or (2) collect or provide 
the relevant acoustic data to substantiate that its modeling approach 
is conservative for both deep- and intermediate-water depths beyond the 
Gulf of Mexico. In addition, the Commission recommends that NMFS (1) 
explain why sound channels with downward refraction, as well as 
seafloor reflections, are not likely to occur during the geophysical 
survey, (2) specify the degree to which both of those parameters would 
affect the estimation (or underestimation) of Level B harassment zones 
in deep- and intermediate- water depths, (3) explain why L-DEO's model 
and other modeling approaches provide more accurate, realistic, and 
appropriate Level A and B harassment zones than BELLHOP (a different 
propagation model favored by the Commission), particularly for deep- 
and intermediate-water depths, and (4) explain why, if L-DEO's model 
and other modeling approaches are considered best available science, 
other action proponents that conduct seismic surveys are not 
implementing similar methods, particularly given their simplicity.
    Response: As noted by the Commission, these comments reflect a 
longstanding disagreement between NMFS and the Commission regarding L-
DEO's approach to modeling the output of their airgun array and its 
propagation through the water column. NMFS has previously responded to 
similar Commission comments on L-DEO's modeling approach. We refer the 
reader to previous Federal Register notices providing responses rather 
than repeat them here (e.g., 84 FR 60059, November 07, 2019; 84 FR 
54849, October 11, 2019; 84 FR 35073, July 22, 2019). Regardless of the 
addition of

[[Page 29105]]

slightly different points or modifications to the language with which 
the Commission expresses these points, the gist of the Commission's 
disagreement with L-DEO's modeling approach remains the same. NMFS 
believes that its prior responses have adequately explained the 
rationale for not following the Commission's recommendations and, 
importantly, why L-DEO's modeling approach is adequate.
    Comment 33: The ENGOs asserted that NMFS must prepare an 
Environmental Impact Statement and cannot rely on the NSF's 
Environmental Assessment (EA) because they believe that there are 
significant environmental impacts. The CBD's comments on the NSF's 
draft EA were incorporated by reference in the ENGOs' comment letter on 
the proposed IHA. CBD's comments on NSF's draft EA primarily concerned 
Southern Resident killer whales, similar to the concerns addressed 
above.
    Response: The NSF's draft EA, which NMFS adopted, was revised in 
consideration of CBD's comments (and those of other public commenters) 
and adequately analyzes the effects of the action. The commenters do 
not provide any information to support their claim of significant 
environmental impacts under NEPA. NMFS has reviewed the NSF's final EA, 
determined it to be sufficient, and adopted that EA and signed a 
Finding of No Significant Impact (FONSI).
    Comment 34: The ENGOs expressed doubt that the proposed activities 
were permissible under the ESA because they would jeopardize the 
continued existence of Southern Resident killer whales, North Pacific 
right whales, humpback whales, and blue whales, among other protected 
species and adversely modify proposed critical habitat. The proposed 
action clearly affects listed species as well as proposed and 
designated critical habitat, and therefore both NMFS and the NSF must 
undergo consultation under the ESA. The ENGOs urged NMFS to fulfill our 
commitment to complete consultation before authorizing any take of 
marine mammals, and requested a public comment period on the products 
of the consultation. The ENGOs strongly believe that NMFS cannot 
authorize the specified activities because they will jeopardize the 
recovery and survival of Southern Resident killer whales and North 
Pacific right whales.
    Response: NMFS has completed consultation under the ESA on our 
proposal to authorize take of listed marine mammals incidental to L-
DEO's survey activities. The NMFS Office of Protected Resources, 
Interagency Cooperation Division issued a Biological Opinion concluding 
that the proposed action is not likely to jeopardize the continued 
existence of ESA-listed 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 seals and 
is not likely to destroy or adversely modify Steller sea lion or 
humpback whale critical habitat. There is no designated critical 
habitat in the action area for the other listed species. The 
Interagency Cooperation Division determined that a public comment 
period on the Biological Opinion was not warranted. The final 
Biological Opinion is available on our website at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities.
    Comment 35: The ENGOs asserted that NMFS cannot approve the 
proposed activity without first consulting with the states of 
Washington and Oregon under the Coastal Zone Management Act (CZMA). The 
CZMA authorizes states with federally approved coastal management 
programs to review applications for Federal licenses or permits to 
conduct activities in, or outside of, the coastal zone that affects 
land uses, water uses, or natural resources within the coastal zone to 
ensure the activity is fully consistent with the state's management 
plan.
    Response: The NSF submitted consistency determinations to 
Washington and Oregon. Both the Washington State Department of Ecology 
and Oregon Coastal Management Program, the respective CZMA authorities 
for Washington and Oregon, concurred with the NSF's determinations. 
NMFS' action of authorizing take of marine mammal is incidental to the 
NSF's action of conducting the survey, therefore NMFS is not required 
to independently submit consistency determinations under CZMA.
    Comment 36: The ENGOs and Deep Green Wilderness expressed concern 
that the proposed survey overlaps with Olympic Coast National Marine 
Sanctuary (OCNMS). The ENGOs reference the National Marine Sanctuaries 
Act (NMSA), which aims to maintain the natural biological communities 
in the national marine sanctuaries, and to protect, and, where 
appropriate, restore and enhance natural habitats, populations, and 
ecological processes. To achieve these purposes, the NMSA requires that 
Federal agency actions internal or external to a national marine 
sanctuary, including private activities authorized by licenses, leases, 
or permits that are likely to destroy, cause the loss of, or injure any 
sanctuary resource are subject to consultation with the Secretary. The 
ENGOs noted that the action agency must follow the recommendations of 
the Secretary to avoid injury to any sanctuary resource or otherwise 
act to prevent and mitigate damage to such resources.
    Response: NMFS satisfied our responsibilities under section 304(d) 
of the NMSA. NMFS and the NSF drafted a joint Sanctuary Resource 
Statement (SRS) to consult with the NOAA Office of National Marine 
Sanctuaries (ONMS) under the NMSA. ONMS provided two recommended 
alternatives to minimize injury and to protect sanctuary resources: (1) 
Limit operations in OCNMS to daylight hours only regardless of depth; 
and 2) use of the secondary support vessel aiding in marine mammal 
observations throughout the entire sanctuary. NMFS has included these 
recommendations in the final IHA.

Changes From the Proposed IHA to Final IHA

    There are numerous changes from the proposed IHA, starting with the 
timing of the survey. The survey was initially proposed to occur in 
summer 2020 but was delayed until summer 2021. Since conclusion of the 
public comment period in May 2020, NMFS has reviewed newly available 
information, including recent draft Stock Assessment Reports, 
information on relevant Unusual Mortality Events, and other scientific 
literature, and incorporated this information into our analysis of 
impacts on marine mammals and their habitat.
    In addition to the timing changes, the survey tracklines have been 
modified to avoid surveying in the areas with the highest expected 
occurrence of Southern Resident killer whales. Between Tillamook Head, 
Oregon and Barkley Sound, British Columbia, L-DEO's planned tracklines 
have been truncated or removed entirely such that the ensonified area 
does not extend within the 100-meter (m) depth contour (see Estimated 
Take section for description of the Level B harassment zones and 
ensonified area). In addition to removing tracklines in nearshore 
shallow waters along the coast, L-DEO also modified tracklines such 
that the ensonified area will not extend within Canadian designated 
Southern Resident and Northern Resident killer whale critical habitat. 
Additionally, under consultation with Canada DFO, L-DEO removed all 
tracklines in waters 100 m or less in Canadian waters. Thus north of 
Tillamook Head, Oregon, no surveys

[[Page 29106]]

will occur in waters 100 m or less (see Figure 1). Based on informal 
recommendations from the Commission, NMFS recalculated the densities of 
Steller sea lions by applying the appropriate pup and non-pup growth 
rates of the population in Washington and British Columbia. Takes of 
all species and stocks have been recalculated using the revised 
tracklines and resulting ensonified areas. Additionally, NMFS has 
revised the mitigation requirements regarding use of a second support 
vessel and daylight-only operations in waters 200 m or less. The 
proposed IHA required the use of the support vessel and limited 
operations to daylight only along the entire survey area in waters 200 
m or less. In consideration of operational practicability, we have 
revised that requirement to apply only between Tillamook Head, Oregon 
and Barkley Sound, British Columbia. Based on consultation with the 
Olympic Coast National Marine Sanctuary (OCNMS), the final IHA requires 
L-DEO to use the support vessel and operate only during daylight hours 
within the OCNMS, regardless of water depth. OCNMS has also been added 
to the list of entities L-DEO must contact each day to obtain sightings 
reports of Southern Resident killer whales in the survey area and, in 
turn, report their own sightings of killer whales to the Sanctuary. 
Finally, as recommended by the Commission, we have clarified the 
required elements that must be included in L-DEO's monitoring report.

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 (2020). PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population (as described in NMFS's 
SARs). While no mortality is anticipated or authorized here, PBR and 
annual serious injury and mortality from anthropogenic sources are 
included here 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. All MMPA stock information 
presented in Table 1 is the most recent available at the time of 
publication and is available in the 2019 SARs (Caretta et al., 2020; 
Muto et al., 2020) and draft 2020 SARs (available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports). Where available, abundance and status 
information is also presented for marine mammals in Canadian waters in 
British Columbia.

                                               Table 1--Marine Mammals That Could Occur in the Survey Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                     ESA/MMPA     Stock abundance (CV,
                                                                                     status;        Nmin, most recent                          Annual M/
            Common name                Scientific name             Stock         strategic (Y/N)    abundance survey)            PBR             SI \3\
                                                                                       \1\                 \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Eschrichtiidae:
    Gray whale....................  Eschrichtius robustus  Eastern North         -/-; N           26,960 (0.05,         801                          131
                                                            Pacific.                               25,849, 2016).
Family Balaenopteridae (rorquals):
    Humpback whale................  Megaptera              California/Oregon/    -/-; Y           2,900 (0.05, 2,784,   16.7                       >42.1
                                     novaeangliae.          Washington.                            2014).
                                                           Central North         -/-; Y           10,103 (0.30, 7,891,  83                            26
                                                            Pacific.                               2006).
    Minke whale...................  Balaenoptera           California/Oregon/    -/-; N           636 (0.72, 369,       3.5                         >1.3
                                     acutorostrata.         Washington.                            2014).
    Sei whale.....................  Balaenoptera borealis  Eastern North         E/D; Y           519 (0.4, 374, 2014)  0.75                        >0.2
                                                            Pacific.
    Fin whale.....................  Balaenoptera physalus  California/Oregon/    E/D; Y           9,029 (0.12, 8,127,   81                         >43.7
                                                            Washington.                            2014).
                                                           Northeast Pacific...  E/D; Y           3,168 (0.26, 2,554,   5.1                          0.6
                                                                                                   2013).
    Blue whale....................  Balaenoptera musculus  Eastern North         E/D; Y           1,496 (0.44, 1,050,   1.2                        >19.4
                                                            Pacific.                               2014).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale...................  Physeter               California/Oregon/    E/D; Y           1,997 (0.57, 1,270,   2.5                          0.4
                                     macrocephalus.         Washington.                            2014).
Family Kogiidae:
    Pygmy sperm whale.............  Kogia breviceps......  California/Oregon/    -/-; N           4,111 (1.12, 1,924,   19                             0
                                                            Washington.                            2014).
    Dwarf sperm whale.............  Kogia sima...........  California/Oregon/    -/-; N           Unknown (Unknown,     Undetermined                   0
                                                            Washington.                            Unknown, 2014).
Family Ziphiidae (beaked whales):
    Cuvier's beaked whale.........  Ziphius cavirostris..  California/Oregon/    -/-; N           3,274 (0.67, 2,059,   21                          <0.1
                                                            Washington.                            2014).

[[Page 29107]]

 
    Baird's beaked whale..........  Berardius bairdii....  California/Oregon/    -/-; N           2,697 (0.6, 1,633,    16                             0
                                                            Washington.                            2014).
    Mesoplodont beaked whales.....  Mesoplodon spp.......  California/Oregon/    -/-; N           3,044 (0.54, 1,967,   20                           0.1
                                                            Washington.                            2014).
Family Delphinidae:
    Bottlenose dolphin............  Tursiops truncatus...  California/Oregon/    -/-; N           1,924 (0.54, 1,255,   11                          >1.6
                                                            Washington offshore.                   2014).
    Striped dolphin...............  Stenella coeruleoalba  California/Oregon/    -/-; N           29,211 (0.2, 24,782,  238                         >0.8
                                                            Washington.                            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 \4\  N/A              22,160 (unknown,      Unknown                  Unknown
                                                                                                   16,522, 2008).
    Northern right whale dolphin..  Lissodelphis borealis  California/Oregon/    -/-; N           26,556 (0.44,         179                          3.8
                                                            Washington.                            18,608, 2014).
    Risso's dolphin...............  Grampus griseus......  California/Oregon/    -/-; N           6,336 (0.32, 4,817,   46                          >3.7
                                                            Washington.                            2014).
    False killer whale............  Pseudorca crassidens.  N/A.................  N/A              N/A.................  N/A                          N/A
    Killer whale..................  Orcinus orca.........  Offshore............  -/-; N           300 (0.1, 276, 2012)  2.8                            0
                                                           Southern Resident...  E/D; Y           73 (N/A, 73, 2019)..  0.13                        >0.4
                                                           Northern Resident...  -/-; N           302 (N/A, 302, 2018)  2.2                          0.2
                                                           West Coast Transient  -/-; N           349 (N/A, 349, 2018)  3.5                          0.4
    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 California/  -/-; N           35,769 (0.52,         475                         >0.6
                                                            Southern Oregon.                       23,749, 2011).
                                                           British Columbia \4\  N/A              8,091 (unknown,       Unknown                  Unknown
                                                                                                   4,885, 2008).
Dall's porpoise...................  Phocoenoides dalli...  California/Oregon/    -/-; N           25,750 (0.45,         172                          0.3
                                                            Washington.                            17,954, 2014).
                                                           British Columbia \4\  N/A              5,303 (unknown,       Unknown                  Unknown
                                                                                                   4,638, 2008).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Northern fur seal.............  Callorhinus ursinus..  Eastern Pacific.....  -/D; Y           608,143 (0.2,         11,067                       387
                                                                                                   514,738, 2018).
                                                           California..........  -/D; N           14,050 (N/A, 7,524,   451                          1.8
                                                                                                   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 \4\  N/A              4,037 (unknown,       Unknown                  Unknown
                                                                                                   1,100, 2008).
    Guadalupe fur seal............  Arctocephalus          Mexico to California  T/D; Y           34,187 (N/A, 31,019,  1,062                       >3.8
                                     philippii townsendi.                                          2013).
Family Phocidae (earless seals):
    Harbor seal...................  Phoca vitulina.......  Oregon/Washington     -/-; N           Unknown (Unknown,     Undetermined                10.6
                                                            Coastal.                               Unknown, 1999).
                                                           British Columbia \4\  N/A              24,916 (Unknown,      Unknown                  Unknown
                                                                                                   19,666, 2008).
    Northern elephant seal........  Mirounga               California Breeding.  -/-; N           179,000 (N/A,         4,882                        8.8
                                     angustirostris.                                               81,368, 2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
1--Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
2--NMFS marine mammal stock assessment reports online at: 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. These rows represent British Columbia abundance estimates, where available, but do not represent
  additional stocks.
5--The California/Oregon/Washington stock of Mesoplodont beaked whales includes six species of beaked whales. Of the six species represented in this
  stock, only Blainville's beaked whales, Hubbs' beaked whales, and Stejneger's beaked whales are expected to be encountered or taken.


[[Page 29108]]

    All species that could potentially occur in the planned 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 only aware of two 
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 planned 
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.
    A detailed description of the species likely to be affected by L-
DEO's geophysical survey, including brief introductions to the species 
and relevant stocks as well as available information regarding 
population trends and threats, and information regarding local 
occurrence, were provided in the Federal Register notice of proposed 
IHA (85 FR 19580; April 7, 2020). Since that time, NMFS has published 
the draft 2020 SARs with updated abundance, PBR, and/or mortality 
information for the Eastern Pacific stock of northern fur seals, West 
Coast Transient stock of killer whales, Central North Pacific stock of 
humpback whales, Northeast Pacific and California/Oregon/Washington 
stocks of fin whale, Eastern North Pacific Southern Resident stock of 
killer whales, and Eastern North Pacific Stock and Pacific Coast 
Feeding Group of gray whales. The relevant information for these stocks 
has been updated in Table 1, however the status of these species and 
stocks has not changed; therefore detailed descriptions are not 
provided here. Please refer to the Federal Register notice of proposed 
IHA for these descriptions. Please also refer to NMFS' website (https://www.fisheries.noaa.gov/find-species) for generalized species accounts.

Biologically Important Areas and Critical Habitat

    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 planned survey 
will 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 project area.
    Prior to 2016, humpback whales were listed under the ESA as an 
endangered species worldwide. Following a 2015 global status review 
(Bettridge et al., 2015), NMFS delineated 14 distinct population 
segments (DPS) with different listing statuses (81 FR 62259; September 
8, 2016) pursuant to the ESA. The DPSs that occur in U.S. waters do not 
necessarily equate to the existing stocks designated under the MMPA and 
shown in Table 1. 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 survey area, three DPSs may occur: The Hawaii DPS (not 
listed), Mexico DPS (threatened), and Central America DPS (endangered). 
On April 21, 2021, NMFS issued a final 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 (86 FR 21082). Critical habitat for the Central America 
DPS and Mexico DPS was established 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 extends from the 50-m isobath out to the 
1200-m isobath; off southern Oregon (south of 42[deg]10' N), it extends 
out to the 2000-m isobath. L-DEO's easternmost planned tracklines occur 
within designated humpback whale critical habitat along the coast.
    Critical habitat for humpbacks has been designated under Canadian 
law in four locations in British Columbia (DFO 2013), including in the 
waters of the survey area off southwestern Vancouver Island. The other 
three locations are located north of the 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). A small portion of L-DEO's planned 
tracklines overlap with Canadian designated humpback whale critical 
habitat off southwest Vancouver Island.
    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). Some segments of L-DEO's planned 
tracklines overlap with these BIAs.
    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 planned 
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

[[Page 29109]]

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 for Southern Resident and Northern 
Resident killer whales (SOR/2018-278, December 13, 2018). As discussed 
above, L-DEO's initial proposed survey tracklines that overlapped with 
Canadian designated critical habitat for killer whales have been 
eliminated.
    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). L-DEO's planned 
tracklines lie about 9 and 13 km away from the two Oregon units of 
Steller sea lion critical habitat.

Unusual Mortality Events

    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 April 5, 2021, a total of 430 stranded gray 
whales have been reported, including 209 in the United States (93 in 
Alaska, 50 in Washington, 9 in Oregon, and 57 in California), 205 in 
Mexico, and 16 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.
    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.
    Elevated strandings of California sea lion pups occurred in 
Southern California between January 2013 and September 2016. As a 
result, NMFS declared a UME. The UME was confined to pup and yearling 
California sea lions, many of which were emaciated, dehydrated, and 
underweight for their age. A change in the availability of sea lion 
prey, especially sardines, a high value food source for nursing 
mothers, was 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. 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. For more information, see https://www.fisheries.noaa.gov/national/marine-life-distress/2013-2017-california-sea-lion-unusual-mortality-event-california.

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 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).

[[Page 29110]]

 
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 planned 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

    The effects of underwater noise from L-DEO's geophysical survey 
activities have the potential to result in behavioral harassment of 
marine mammals in the vicinity of the survey area. The notice of 
proposed IHA (85 FR 19580; April 7, 2020) included a discussion of the 
effects of anthropogenic noise on marine mammals and the potential 
effects of underwater noise from L-DEO's geophysical survey activities 
on marine mammals and their habitat. That information and analysis is 
incorporated by reference into this final IHA determination and is not 
repeated here; please refer to the notice of proposed IHA (85 FR 19580; 
April 7, 2020). The referenced information includes a summary and 
discussion of the ways that the specified activity may impact marine 
mammals and their habitat. Consistent with the analysis in our prior 
Federal Register notices for similar L-DEO surveys and after 
independently evaluating the analysis in L-DEO's application, we 
determine that the survey is likely to result in the takes described in 
the Estimated Take section of this document and that other forms of 
take are not expected to occur.
    The Estimated Take section later in this document includes a 
quantitative analysis of the number of individuals that are expected to 
be taken by this activity. The Negligible Impact Analysis and 
Determination section considers the content of this section, the 
Estimated Take section, and the 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

    The notice of proposed IHA provided a brief technical background on 
sound, on the characteristics of certain sound types, and on metrics 
used in the proposal inasmuch as the information was 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. 
Please see that document (85 FR 19580; April 7, 2020) for additional 
information. For general information on sound and its interaction with 
the marine environment, please see, e.g., Au and Hastings (2008); 
Richardson et al. (1995); Urick (1983).

Estimated Take

    This section provides an estimate of the number of incidental takes 
authorized 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 will 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 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 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 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,

[[Page 29111]]

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 microPascal ([mu]Pa) root mean square (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 planned 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 planned seismic survey includes 
the use of impulsive (seismic airguns) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                    PTS onset acoustic thresholds \*\ (received level)
----------------------------------------------------------------------------------------------------------------
             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 planned 2D survey will acquire data 
using the 36-airgun array with a total discharge volume of 6,600 cubic 
inches (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

[[Page 29112]]

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 R/V 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 R/V 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 survey will 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 
planned 2021 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.
    The estimated distances to the Level B harassment isopleth for the 
R/V 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
                                                                                    Water depth     harassment
                        Source and volume                          Tow depth (m)        (m)       zone (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 cumulative sound exposure level (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 R/V Langseth 
airgun array were derived from calculating the modified far-field 
signature (Table 5). The farfield signature is often used as a 
theoretical representation of the source level. To compute the farfield 
signature, the source level is estimated at a large distance below the 
array (e.g., 9 km), and this level is back projected mathematically to 
a notional distance of 1 m from the array's geometrical center. 
However, when the source is an array of multiple airguns separated in 
space, the source level from the theoretical farfield signature is not 
necessarily the best measurement of the source level that is physically 
achieved at the source (Tolstoy et al. 2009). Near the source (at short 
ranges, distances <1 km), the pulses of sound pressure from each 
individual airgun in the source array do not stack constructively, as 
they do for the theoretical farfield signature. The pulses from the 
different airguns spread out in time such that the source levels 
observed or modeled are the result of the summation of pulses from a 
few airguns, not the full array (Tolstoy et al. 2009). At larger 
distances, away from the source array center, sound pressure of all the 
airguns in the array stack coherently, but not within one time sample, 
resulting in smaller source levels (a few dB) than the source level 
derived from the farfield signature. Because the farfield signature 
does not take into account the large array effect near the source and 
is calculated as a point source, the modified farfield signature is a 
more appropriate measure of the sound source level for distributed 
sound sources, such as airgun arrays. L-DEO used the acoustic modeling 
methodology as used for Level B harassment with a small grid step of 1 
m in both the inline and depth directions. The propagation modeling 
takes into account all airgun interactions at short distances from the 
source, including interactions between subarrays, which are modeled 
using the NUCLEUS software to estimate the notional signature and 
MATLAB software to calculate the pressure signal at each mesh point of 
a grid.
    For a more complete explanation of this modeling approach, please 
see ``Appendix A: Determination of Mitigation Zones'' in the IHA 
application.

[[Page 29113]]



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

    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 R/V 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 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 this 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 relevant peak isopleth 
distances for these three hearing groups would in all cases be expected 
to be within the near-field of the array where the definition of source 
level breaks down. Therefore, actual locations within this distance of 
the array center where the sound level exceeds the relevant criteria 
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. For full discussion of these concepts, 
please see our notice of proposed IHA (85 FR 19580; April 7, 2020).
    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 have not authorized any Level A harassment for these 
species.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density,

[[Page 29114]]

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 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 
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-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, a geographic 
information system (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 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)

[[Page 29115]]

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 Pacific Coast Feeding Group (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 acting on that request.
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 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

[[Page 29116]]

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 was initially planned to 
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 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. The Commission noted that we had used the non-pup 
population growth rate to project the population of both non-pups and 
pups. Additionally, the Commission suggested we include the British 
Columbia population in our projections. We have revised the population 
projections and resulting density estimates accordingly.
    Sea lions from northern California and southern Oregon rookeries 
migrate north in September following the breeding season and winter in 
northern

[[Page 29117]]

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 7 years from 2010 to 2017, the Navy 
calculated a projected 2017 abundance estimate of 232,399 elephant 
seals (Caretta et al., 2017b; Lowry et al., 2014). Male and female 
distributions at sea differ both seasonally and spatially. Pup counts 
reported by Lowry et al., (2014) and life tables compiled by Condit et 
al., (2014) were used to determine the proportion of males and females 
in the population, which was estimated to be 56 percent female and 44 
percent male. Females are assumed to be at sea 100 percent of the time 
within their seasonal distribution area in fall and summer (Robinson et 
al., 2012). Males are at sea approximately 90 percent of the time in 
fall and spring, remain ashore through the entire winter, and spend one 
month ashore to molt in the summer (i.e., are at sea 66 percent of the 
summer). Monthly distribution maps produced by Robinson et al. (2012) 
showing the extent of foraging areas used by satellite tagged female 
elephant seals were used to estimate the spatial areas to calculate 
densities. Although the distributions were based on tagged female 
seals, Le Boeuf et al. (2000) and Simmons et al. (2007) reported 
similar tracks by males over broad spatial scales. The spatial areas 
representing each monthly distribution were calculating using GIS and 
then averaged to produce seasonally variable areas and resulting 
densities.
    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 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 8 year limit beyond which 
NMFS will not confirm abundance in a SAR (Caretta et

[[Page 29118]]

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).
    No significant new information is available since we published the 
notice of proposed IHA, and no changes have been made, other than those 
described in the Changes from the Proposed IHA section, provided 
previously in this document.
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/  100-1,000 m/   Deep >1,000 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................       0.4804893       0.0035811            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).
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

[[Page 29119]]

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 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 L-DEO's EA for the ensonified areas in each category). The areas 
provided in Tables 8 and 9 here have been updated from those provided 
in Tables 8 and 9 of the notice of proposed IHA (85 FR 19580; April 7, 
2020) based on the revised planned survey tracklines.

         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        3,580.73
    Intermediate 100-1,000 m..................  160 dB..........................       \b\ 9,468       23,562.43
    Deep >1,000 m.............................  160 dB..........................       \b\ 6,733       52,438.71
        Overall...............................  ................................  ..............       79,581.85
Level A Harassment:
    All depth zones...........................  LF Cetacean.....................           426.9        5,334.55
                                                MF Cetacean.....................            13.6          171.42
                                                HF Cetacean.....................           268.3        3,363.99
                                                Otariid.........................            10.6          133.61
                                                Phocid..........................            43.7          550.53
----------------------------------------------------------------------------------------------------------------
\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           5,888
                                       0.000001-0.002803          15,470
                                       0.002804-0.005615             342
                                       0.005616-0.009366               0
                                       0.009367-0.015185               0
J.................................              0.000000           6,427
                                       0.000001-0.001991           5,556
                                       0.001992-0.005010               0
                                       0.005011-0.009602               0
                                       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 survey outside of Canadian 
territorial waters are shown in Table 10. These numbers have changed 
from those provided in Table 10 of the notice of proposed IHA (85 FR 
19580; April 7, 2020) because of the revised planned survey tracklines.

[[Page 29120]]



                               Table 10--Estimated Taking by Level A and Level B Harassment, and Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                  Estimated take               Total
                  Species                          MMPA stock \a\              Stock     --------------------------------   authorized      Percent of
                                                                             abundance       Level 1B        Level 1A          take         MMPA stock
--------------------------------------------------------------------------------------------------------------------------------------------------------
LF Cetaceans:
                                            Central North Pacific.......          10,103             112              29         \b\ 141            1.40
    Humpback whale........................  California/Oregon/Washington           2,900  ..............  ..............  ..............            4.86
    Blue whale............................  Eastern North Pacific.......           1,647              40              11              51            3.10
    Fin whale.............................  California/Oregon/Washington           9,029              94               1              95            1.05
                                            Northeast Pacific...........           3,168  ..............  ..............  ..............            3.00
    Sei whale.............................  Eastern North Pacific.......          27,197              30               2              32            0.12
    Minke whale...........................  California/Oregon/Washington          25,000              96               7             103            0.41
    Gray whale............................  Eastern North Pacific.......          26,960              43               1              44            0.16
MF Cetaceans:
    Sperm whale...........................  California/Oregon/Washington          26,300              72               0              72            0.27
    Baird's beaked whale..................  California/Oregon/Washington           2,697              84               0              84            3.12
    Small beaked whale....................  California/Oregon/Washington           6,318             242               0         \c\ 242            3.83
    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             112               0         \d\ 179            0.02
    Pacific white-sided dolphin...........  California/Oregon/Washington          26,814           6,084               0           6,084           22.69
    Northern right-whale dolphin..........  California/Oregon/Washington          26,556           4,318               0           4,318           16.26
    Risso's dolphin.......................  California/Oregon/Washington           6,336           1,664               0           1,664           26.26
    False killer whale....................  n/a.........................         Unknown             n/a             n/a           \e\ 5         \f\ n/a
    Killer whale..........................  Southern Resident...........              73              10               0              10           13.70
                                            Northern Resident...........             302              73               0              73           24.17
                                            West Coast Transient........             349  ..............  ..............  ..............           20.92
                                            Offshore....................             300  ..............  ..............  ..............           24.33
    Short-finned pilot whale..............  California/Oregon/Washington             836              20               0          \d\ 29            3.47
HF Cetaceans:
    Pygmy/dwarf sperm whale...............  California/Oregon/Washington           4,111             125               5             130            3.16
    Dall's porpoise.......................  California/Oregon/Washington          27,750           9,762             488          10,250       \g\ 36.94
    Harbor porpoise.......................  Northern Oregon/Washington            21,487           7,958             283           8,241       \g\ 38.35
                                             Coast.
                                            Northern California/Southern          35,769  ..............  ..............  ..............           23.04
                                             Oregon.
Otariid Seals:
    Northern fur seal.....................  Eastern Pacific.............         608,143           4,592               0           4,592            0.76
                                            California..................          14,050  ..............  ..............  ..............           32.68
    Guadalupe fur seal....................  Mexico to California........          34,187           2,048               0           2,048            5.99
    California sea lion...................  U.S.........................         257,606             889               0             889            0.35
    Steller sea lion......................  Eastern U.S.................          43,201           7,504               0           7,504           17.37
Phocid Seals:
    Northern elephant seal................  California Breeding.........         179,000           2,754               0           2,754            1.54
    Harbor seal...........................  Oregon/Washington Coast.....      \h\ 24,732           3,887               0           3,887           15.72
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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 authorized 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 (Appendix B of L-DEO's application describes potential take estimates of each species represented in the guild,
  but we present the authorized take of small beaked whales as a whole).
\d\ Authorized take increased to mean group size from Barlow (2016).
\e\ Authorized take increased to mean group size from Mobley et al. (2000).
\f\ False killer whales that may be taken during this survey are not likely to belong to any designated stock. Therefore we cannot determine the percent
  of stock that may be taken, but we assume that five individuals would be considered small relative to the abundance of the population they belong to.
\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.


[[Page 29121]]

    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 have authorized a 
different number of takes of mid-frequency cetaceans and pinnipeds by 
Level A harassment than the number estimated by L-DEO (see Appendix B 
in L-DEO's IHA application).

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 and impact on 
operations.
    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 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 will implement mitigation 
measures for marine mammals. Mitigation measures that will 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. 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 must 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 must be designated as the lead for the 
entire protected species observation team. The lead PSO must 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 must coordinate to ensure 
360[deg] visual coverage around the vessel from the most appropriate 
observation posts, and must conduct visual observations using 
binoculars and the naked eye while free from distractions and in a 
consistent, systematic, and diligent manner.
    PSOs must establish and monitor the exclusion and buffer zones. 
These zones must 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

[[Page 29122]]

ramp-up), detections of marine mammals within the buffer zone (but 
outside the exclusion zone) must 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 must 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 must be relayed to the PSO team. During good conditions 
(e.g., daylight hours; Beaufort sea state (BSS) 3 or less), visual PSOs 
must 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 along the coast between Tillamook Head, Oregon and Barkley Sound, 
British Columbia (between latitudes 45.9460903[deg] N and 
48.780291[deg] N), and within the boundaries of Olympic Coast National 
Marine Sanctuary, a second vessel with additional PSOs must travel 
approximately 5 km ahead of the R/V Langseth. Two PSOs must be on watch 
on the second vessel during all such survey operations and must alert 
PSOs on the R/V Langseth of any marine mammal observations so that they 
may be prepared to initiate shutdowns. This requirement has been 
modified from what was included in the proposed IHA, which proposed 
using the second vessel through the entire survey area in waters under 
200 m. This requirement was primarily intended to increase the 
likelihood of PSOs detecting Southern Resident killer whales. However, 
L-DEO has described practicability concerns with the second vessel, 
including high cost and limited availability for the time period 
specified. NMFS carefully considered the area in which the second 
vessel would effect the most reduction in impacts to Southern Resident 
killer whales and, accordingly, the area requiring the second vessel 
has been revised to reflect the areas of highest occurrence (based on 
Navy, 2019), between Tillamook Head and Barkley Sound and within the 
boundaries of Olympic Coast National Marine Sanctuary.
    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 will 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 will 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 
will be monitored in real time so that the visual observers can be 
advised when cetaceans are detected.
    The R/V Langseth must use a towed PAM system, which must be 
monitored by at a minimum one on duty acoustic PSO beginning at least 
30 minutes prior to ramp-up and at all times during use of the acoustic 
source. Acoustic PSOs may be on watch for a maximum of 4 consecutive 
hours followed by a break of at least 1 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 2 hours;
     NMFS is notified via email as soon as practicable with the 
time and location in which operations began occurring without an active 
PAM system; and
     Operations with an active acoustic source, but without an 
operating PAM system, do not exceed a cumulative total of 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 must establish a minimum EZ with a 500-m 
radius. The 500-m EZ must 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 must 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.

[[Page 29123]]

    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 must 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 must begin by activating a single airgun of the 
smallest volume in the array and must 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 must 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 must 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 has the authority to delay the start of survey operations or to 
call for shutdown of the acoustic source if a marine mammal is detected 
within the applicable EZ. The operator must also establish and maintain 
clear lines of communication directly between PSOs on duty and crew 
controlling the acoustic source to ensure that shutdown commands are 
conveyed swiftly while allowing PSOs to maintain watch. When both 
visual and acoustic PSOs are on duty, all detections must be 
immediately communicated to the remainder of the on-duty PSO team for 
potential verification of visual observations by the acoustic PSO or of 
acoustic detections by visual PSOs. When the airgun array is active 
(i.e., anytime one or more airguns is active, including during ramp-up) 
and (1) a marine mammal appears within or enters the applicable 
exclusion zone and/or (2) a marine mammal (other than delphinids, see 
below) is detected acoustically and localized within the applicable 
exclusion zone, the acoustic source must be shut down. When shutdown is 
called for by a PSO, the acoustic source must be immediately 
deactivated and any dispute resolved only following deactivation. 
Additionally, shutdown must 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 must 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 must 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, killer 
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

[[Page 29124]]

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 R/V 
Langseth to revisit the missed track line to reacquire data, resulting 
in an overall increase in the total sound energy input to the marine 
environment and an increase in the total duration over which the survey 
is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large 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 must 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 knots or less when mother/
calf pairs, pods, or large assemblages of any marine mammal are 
observed near a vessel;
    3. All vessels must maintain a minimum separation distance of 100 m 
from large whales (i.e., sperm whales and all mysticetes);
    4. All vessels must attempt to maintain a minimum separation 
distance of 50 m from all other marine mammals, with an exception made 
for those animals that approach the vessel; and
    5. When marine mammals are sighted while a vessel is underway, the 
vessel should take action as necessary to avoid violating the relevant 
separation distance (e.g., attempt to remain parallel to the animal's 
course, avoid excessive speed or abrupt changes in direction until the 
animal has left the area). If marine mammals are sighted within the 
relevant separation distance, the vessel should reduce speed and shift 
the engine to neutral, not engaging the engines until animals are clear 
of the area. This recommendation does not apply to any vessel towing 
gear.

Operational Restrictions

    While the R/V Langseth is surveying in waters 200 m deep or less 
along the coast between Tillamook Head, Oregon and Barkley Sound, 
British Columbia (between latitudes 45.9460903[deg] N and 
48.780291[deg] N), and within the boundaries of Olympic Coast National 
Marine Sanctuary, survey operations must 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, North Pacific right whale, 
aggregation of six or more large whales, large whale with a calf). The 
proposed IHA included this requirement to operate only during daylight 
hours in waters 200 m deep or less throughout the entire survey area. 
We have revised that requirement to apply only between Tillamook Head 
and Barkley Sound and within the boundaries of Olympic Coast National 
Marine Sanctuary because those are the areas with the highest expected 
Southern Resident killer whale

[[Page 29125]]

occurrence, and we determined that requiring this operational 
restriction throughout the entire survey area was not practicable, in 
consideration of cost and vessel availability concerns.

Communication

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

Mitigation Measures in Canadian Waters

    As stated 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. Therefore, the mitigation requirements 
described above do not apply within Canadian territorial waters. The 
MMPA is applicable in the EEZs of foreign nations, and therefore, the 
mitigation measures above apply within the Canadian EEZ. However, L-DEO 
also consulted with Canada's DFO under the Canada Species at Risk Act 
and must also comply with DFO's mitigation requirements within the 
Canadian EEZ in order to avoid causing the death of fish or marine 
mammals and/or the harmful alteration, disruption, or destruction of 
fish habitat, or causing prohibited effects to aquatic species at risk. 
Within the Canadian EEZ, L-DEO must:
     Conduct seismic survey activities outside of designated 
Killer Whale Critical Habitat (KWCH) with a setback that ensures that 
the estimated sound pressure level has diminished to <=160 dB rms re: 1 
[mu]Pa at the boundary of KWCH;
     Initiate an immediate and complete shutdown of the airgun 
array if a killer whale (all ecotypes), North Pacific right whale, 
whale with calf (any species) or aggregation of whales (any species) is 
observed;
     Initiate an immediate and complete shutdown of the airgun 
array if a sperm whale or a beaked whale (any species) is sighted 
within 1,500 m of the airgun array;
     For other observations of marine mammals, initiate an 
immediate and complete shutdown of the airgun array if these animals 
are observed within an established EZ with a radius of 1,000 m;
     Refrain from conducting seismic surveys in waters less 
than 100 m in depth;
     Conduct seismic surveys in waters 100 to 200 m deep during 
daylight hours only, with a second vessel having two marine mammal 
observers on watch, positioned 5 km ahead of the R/V Langseth;
     Combine enhanced visual observations (e.g., reticle and 
big-eye binoculars, night vision devices and digital cameras) with non-
visual detection methods (e.g., infrared technology (FLIR) and passive 
acoustic monitoring) to increase the likelihood of detecting marine 
mammals during ramp up, Beaufort sea states >3, and nighttime survey 
operations; and
     Monitor the established EZ with a radius of 1,000 m for 60 
minutes prior to initial start-up of the airgun array or resumption of 
operations following a complete shutdown to allow for the detection of 
deep diving animals.
    While operating within the Canadian EEZ but outside Canadian 
territorial waters, if mitigation requirements in the IHA differ from 
the requirements established by DFO, L-DEO must adhere to the most 
protective measure (e.g., larger EZ, visual monitoring procedures).

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 survey is to investigate the geologic 
features that occur within that area. Therefore, NMFS has not 
prohibited L-DEO from operating in 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 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.

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 
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,

[[Page 29126]]

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 must take place during daytime 
airgun operations. During seismic operations, at least five visual PSOs 
must be based aboard the R/V Langseth. Two visual PSOs must 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 must be conducted 
in accordance with the following requirements:
     The operator must 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 must 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 must 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 must be independent, dedicated, trained visual and 
acoustic PSOs and must be employed by a third-party observer provider;
     PSOs must 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 must have successfully completed an approved PSO 
training course appropriate for their designated task (visual or 
acoustic). Acoustic PSOs are required to complete specialized training 
for operating PAM systems and are encouraged to have familiarity with 
the vessel with which they will be working;
     PSOs can act as acoustic or visual observers (but not at 
the same time) as long as they demonstrate that their training and 
experience are sufficient to perform the task at hand;
     NMFS must review and approve PSO resumes accompanied by a 
relevant training course information packet that includes the name and 
qualifications (i.e., experience, training completed, or educational 
background) of the instructor(s), the course outline or syllabus, and 
course reference material as well as a document stating successful 
completion of the course;
     NMFS shall have one week to approve PSOs from the time 
that the necessary information is submitted, after which PSOs meeting 
the minimum requirements shall automatically be considered approved;
     PSOs must successfully complete relevant training, 
including completion of all required coursework and passing (80 percent 
or greater) a written and/or oral examination developed for the 
training program;
     PSOs must have successfully attained a bachelor's degree 
from an accredited college or university with a major in one of the 
natural sciences, a minimum of 30 semester hours or equivalent in the 
biological sciences, and at least one undergraduate course in math or 
statistics; and
     The educational requirements may be waived if the PSO has 
acquired the relevant skills through alternate experience. Requests for 
such a waiver must 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 must use standardized data 
collection forms, whether hard copy or electronic. PSOs must record 
detailed information about any implementation of mitigation 
requirements, including the distance of animals to the acoustic source 
and description of specific actions that ensued, the behavior of the 
animal(s), any observed changes in behavior before and after 
implementation of mitigation, and if shutdown was implemented, the 
length of time before any subsequent ramp-up of the acoustic source. If 
required mitigation was not implemented, PSOs should record a 
description of the circumstances. At a minimum, the following 
information must be recorded:
     Vessel 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.);

[[Page 29127]]

     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 must be submitted to NMFS within 90 days after the end of 
the cruise. The report must describe the operations that were conducted 
and sightings of marine mammals near the operations. The report must 
provide full documentation of methods, results, and interpretation 
pertaining to all monitoring. The 90-day report must summarize the 
dates and locations of seismic operations, and all marine mammal 
sightings (dates, times, locations, activities, associated seismic 
survey activities). The report must also include estimates of the 
number and nature of exposures that occurred above the harassment 
threshold based on PSO observations and including an estimate of those 
that were not detected, in consideration of both the characteristics 
and behaviors of the species of marine mammals that affect 
detectability, as well as the environmental factors that affect 
detectability.
    The draft report must 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 must be provided in ESRI shapefile format and include 
the UTC date and time, latitude in decimal degrees, and longitude in 
decimal degrees. All coordinates must be referenced to the WGS84 
geographic coordinate system. In addition to the report, all raw 
observational data must 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 must 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 must 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 measures were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
     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 must 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.,

[[Page 29128]]

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 must immediately report 
observations of Southern Resident killer whales and North Pacific right 
whales to OPR, NMFS. L-DEO must also immediately report all sightings 
of Southern Resident killer whales and North Pacific right whales 
within Olympic Coast National Marine Sanctuary to the Sanctuary.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    To avoid repetition, our analysis applies to all species listed in 
Tables 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 have authorized 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 survey (including the 
portion of the survey that would occur within the Canadian territorial 
waters (approximately six percent of the survey) (Table 11).

                                          Table 11--Total Estimated Take Including Canadian Territorial Waters
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Estimated take (excluding        Estimated take (within           Total estimated take
                                                           Canadian territorial waters)    Canadian territorial waters)  -------------------------------
                         Species                         ----------------------------------------------------------------
                                                              Level B         Level A         Level B         Level A         Level B         Level A
--------------------------------------------------------------------------------------------------------------------------------------------------------
LF Cetaceans:
    Humpback whale......................................             112              29              21               1             133              30
    Blue whale..........................................              40              11               7               1              47              11
    Fin whale...........................................              94               1               2               0              96               1
    Sei whale...........................................              30               2               2               0              31               2
    Minke whale.........................................              96               7               6               0             101               7
    Gray whale..........................................              43               1              23               1              66               2
MF Cetaceans:
    Sperm whale.........................................              72               0               1               0              73               0
    Baird's beaked whale................................              84               0               1               0              85               0
    Small beaked whale..................................             242               0               5               0             247               0
    Bottlenose dolphin..................................               1               0               0               0               1               0
    Striped dolphin.....................................               7               0               0               0               7               0
    Short-beaked common dolphin.........................             112               0               4               0             116               0
    Pacific white-sided dolphin.........................            6093               0             333               0            6426               0
    Northern right-whale dolphin........................            4320               0             118               0            4438               0
    Risso's dolphin.....................................            1669               0             145               0            1814               0
    False killer whale..................................               5               0               0               0               5               0
    Killer whale (Southern Resident)....................              10               0               1               0              11               0
    Killer whale (Northern Resident)....................              73               0               4               0              77               0
    Killer whale (West Coast Transient).................
    Killer whale (Offshore).............................

[[Page 29129]]

 
    Short-finned pilot whale............................              20               0               1               0              21               0
HF Cetaceans:
    Pygmy/dwarf sperm whale.............................             125               5               8               0             134               6
    Dall's porpoise.....................................            9762             488             696              23           10457             511
    Harbor porpoise.....................................            7958             283            2403              87           10361             369
Otariid Pinnipeds:
    Northern fur seal...................................            4424               0              54               0            4478               0
    Guadalupe fur seal..................................            2048               0             113               0            2161               0
    California sea lion.................................             889               0             137               0            1026               0
    Steller sea lion....................................            7504               0            1920               0            9424               0
Phocid Pinnipeds:
    Northern elephant seal..............................            2754               0             164               0            2918               0
    Harbor seal.........................................            3887               0            1623               0            5510               0
--------------------------------------------------------------------------------------------------------------------------------------------------------

    NMFS does not anticipate that serious injury or mortality will 
occur as a result of L-DEO's planned survey, even in the absence of 
mitigation, and none are authorized. As discussed in the Potential 
Effects section of the notice of proposed IHA (85 FR 19580; April 7, 
2020), non-auditory physical effects, stranding, and vessel strike are 
not expected to occur.
    We have authorized 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 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 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 in detail 
in the Potential Effects of the Specified Activity on Marine Mammals 
and their Habitat section of the notice of proposed IHA (85 FR 19580; 
April 7, 2020). 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 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 survey beginning in June 2021 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 planned, 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 2021.
    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

[[Page 29130]]

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 must 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 established along the 
U.S. West Coast (86 FR 21082; April 21, 2021), 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 small portion of L-DEO's seismic survey 
will occur in or near these established or proposed 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 survey. The Orford Reef and Rogue Reef 
critical habitats are located 7 km and 9 km from the nearest planned 
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 established along the U.S. 
West Coast (86 FR 21082; April 21, 2021). The 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 extend further offshore. NMFS determined 
that prey within humpback whale feeding areas are essential to the 
conservation of each of the three DPSs of humpback whales for which 
critical habitat was established (Mexico, Central America, and Western 
North Pacific DPSs). Critical habitat was therefore designated 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 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 must 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.
    As discussed earlier, in response to comments from the ENGOs, we 
acknowledge ongoing concern over the health and growth of the 
California/Oregon/Washington stock of humpback whales, due to vessel 
strikes and other factors. As described above, though, impacts from 
this seismic survey are not expected to impact the fitness of any 
individuals and thereby will not alone, or incrementally in combination 
with other baseline stressors, adversely affect the stock through 
impacts on rates of recruitment or survival.
Southern Resident Killer Whales
    In acknowledgment of our concern regarding the status of Southern 
Resident killer whales, including low abundance and a decreasing trend, 
we address impacts to this stock separately in this section.
    L-DEO's planned 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

[[Page 29131]]

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 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 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 30 percent of L-DEO's total tracklines occur within 
the 200-m isobath along the coast of Oregon, Washington, and British 
Columbia. L-DEO is 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 must 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 no survey tracklines or ensonified area 
overlap with the areas of highest estimated densities of Southern 
Resident killer whales (see Table 9 of this notice and Figures 7-9 and 
7-11 in the U.S. Navy's MSDD (U.S. Navy 2019)). While Southern Resident 
killer whales may be encountered outside of these areas of highest 
density, the likelihood is significantly decreased and the relatively 
small amount of time of altered behavior would not likely affect their 
overall foraging ability. 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 authorized. Authorized takes of Southern Resident killer whales 
would be limited to Level B harassment in the form of behavioral 
disturbance. We anticipate 11 instances of Level B harassment of 
Southern Resident killer whales (10 takes by Level B harassment 
authorized in this IHA and one take by Level B harassment within 
Canadian territorial waters), 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 survey will be of short duration (37 days of seismic 
operations), and the acoustic ``footprint'' of the survey is small 
relative to the ranges of the marine mammals that will potentially be 
affected. Sound levels will increase in the marine environment in a 
relatively small area surrounding the vessel compared to the range of 
the marine mammals within the 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 prescribed 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 required 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 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.
    While operating within the Canadian EEZ, L-DEO will implement 
certain measures prescribed by Canada's DFO that are more protective 
than those prescribed by NMFS under the MMPA. These include a 
requirement to avoid operating within or nearby designated Southern 
Resident or Northern Resident killer whale critical habitat such that 
the ensonified area above the 160 dB rms threshold does not extend 
inside critical habitat, shutting down the airgun array if a sperm 
whale or a beaked whale (any species) is observed within 1,500 m, and 
shutting down the airgun array if any species of marine mammal is 
observed within 1,000 m of the array. Additionally, throughout the 
entire survey area within the Canadian EEZ, L-DEO will not conduct 
survey operations in waters 100 m or less and will conduct seismic 
surveys in waters 100 to 200 m deep during daylight hours only, with a 
second vessel having two marine mammal observers on watch, positioned 5 
km ahead of the R/V Langseth. L-DEO must also combine enhanced visual 
observations (e.g., reticle and big-eye binoculars, night vision 
devices and digital cameras) with non-visual detection methods (e.g., 
infrared technology (FLIR) and PAM) to increase the likelihood of 
detecting marine mammals during ramp up, Beaufort sea states >3, and 
night time survey operations. Finally, L-DEO must monitor the 
established exclusion zone with a radius of 1,000 m for 60 minutes 
prior to initial start-up of the airgun array or resumption of 
operations following a complete shutdown to allow for the detection of 
deep diving animals.
    NMFS concludes that exposures to marine mammal species and stocks 
due to L-DEO's planned survey will 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

[[Page 29132]]

authorized take to impact annual rates of recruitment or survival.
    In summary and as described above, the following factors primarily 
support our 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 
authorized;
     The planned activity is temporary and of relatively short 
duration (37 days);
     The anticipated impacts of the activity on marine mammals 
will 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 planned 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 survey 
will be temporary and spatially limited, and impacts to marine mammal 
foraging will be minimal; and
     The mitigation requirements, 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 authorization 
of Southern Resident killer whale take is not expected to 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 prescribed mitigation and 
monitoring measures, NMFS finds that the total marine mammal take from 
the planned 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 two stocks for which the estimated instances of take 
appear high when compared to the stock abundance (Table 10)--the 
California/Oregon/Washington Dall's porpoise stock and the Northern 
Oregon/Washington Coast harbor porpoise stock. However, when other 
qualitative factors are used to inform an assessment of the likely 
number of individual marine mammals taken, the resulting numbers are 
appropriately considered small. We discuss these in further detail 
below.
    For all other stocks (aside from the two referenced above and 
described below), the authorized 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). Additionally, we note that the authorized take 
is compared to the stock abundance for MMPA designated stocks, which 
for many species are limited to U.S. waters and do not include animals 
within the Canadian EEZ. Therefore, for species with transboundary 
populations, the actual percentage of the population affected is lower 
than that shown in Table 10.
    The expected take of the California/Oregon/Washington stock of 
Dall's porpoises, as a proportion of the population abundance, is 36.94 
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 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 will be exposed to the 
seismic survey.
    When assuming all estimated takes of harbor porpoise (8,241 total 
takes by Level A and B harassment) will occur to the Northern Oregon/
Washington Coast stock, the take appears high relative to stock 
abundance (38.35 percent). In reality, takes will occur to both the 
Northern Oregon/Washington Coast and Northern California/Southern 
Oregon 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 will 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 planned 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 (2,747 total 
Level A and Level B takes) represent 7.68 percent of the stock 
abundance, which NMFS considers to be small relative to the stock 
abundance. In addition, the 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 (5,494 takes) represent 
25.57 percent of the stock abundance, which

[[Page 29133]]

NMFS considers to be small relative to the stock abundance. 
Additionally, 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 18.57 percent of the combined British Columbia and Northern 
Oregon/Washington Coast abundance estimates, which NMFS considers to be 
small relative to the stock abundance.
    Based on the analysis contained herein of the planned activity 
(including the required mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS 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 will not 
have an unmitigable adverse impact on the availability of such species 
or stocks for taking for subsistence purposes.

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 has adopted the NSF's EA, as we have determined 
that it includes adequate information analyzing the effects on the 
human environment of issuing the IHA, and prepared a FONSI. NSF's EA is 
available at https://www.nsf.gov/geo/oce/envcomp/, and NMFS' FONSI is 
available at https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities.

Endangered Species Act (ESA)

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS consults internally whenever we propose to authorize take for 
endangered or threatened species.
    The NMFS Office of Protected Resources ESA Interagency Cooperation 
Division issued a Biological Opinion under section 7 of the ESA, on the 
issuance of an IHA to L-DEO under section 101(a)(5)(D) of the MMPA by 
the NMFS OPR Permits and Conservation Division. The Biological Opinion 
concluded that the proposed action is not likely to jeopardize the 
continued existence of ESA-listed 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 seals, 
and is not likely to destroy or adversely modify designated Steller sea 
lion or humpback whale critical habitat. There is no designated 
critical habitat in the action area for the other ESA-listed species.

Authorization

    As a result of these determinations, NMFS has issued an IHA to L-
DEO for conducting a marine geophysical survey in the northeast Pacific 
Ocean beginning in June 2021, provided the previously mentioned 
mitigation, monitoring, and reporting requirements are incorporated.

    Dated: May 24, 2021.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2021-11375 Filed 5-27-21; 8:45 am]
BILLING CODE 3510-22-P