Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey in the Aleutian Islands, 55645-55666 [2020-19815]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 85, Number 175 (Wednesday, September 9, 2020)]
[Notices]
[Pages 55645-55666]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-19815]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XA439]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey in the 
Aleutian Islands

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

ACTION: Notice; issuance of 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 
the Lamont-Doherty Earth Observatory of Columbia University (L-DEO) to 
incidentally harass marine mammals during a marine geophysical survey 
in the Aleutian Islands, Alaska.

DATES: The authorization is effective for a period of one year, from 
September 1, 2020, through August 31, 2021.

FOR FURTHER INFORMATION CONTACT: Ben Laws, Office of Protected 
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Availability

    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: www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatory-marine-geophysical-survey-2. In case of problems accessing these documents, please call 
the contact listed above.

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. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.

Summary of Request

    On March 27, 2020, NMFS received a request from L-DEO for an IHA to 
take marine mammals incidental to a marine geophysical survey along and 
across the Aleutian Andreanof Arc in Alaska. L-DEO submitted a revised 
version of the application, which was deemed adequate and complete, on 
June 25, 2020. NMFS published a proposed IHA for public review and 
comment on July 28, 2020 (85 FR 45389). NMFS has authorized take of 24 
species of marine mammals by harassment. For seven of these species, 
taking by Level A and Level B harassment is authorized, with only Level 
B harassment authorized for the remaining 17 species.

Description of Proposed Activity

Overview

    Researchers from L-DEO and Woods Hole Oceanographic Institution 
(WHOI), with funding from the National Science Foundation (NSF), 
proposed to conduct a high-energy seismic survey from the Research 
Vessel (R/V) Marcus G. Langseth (Langseth) along and across the 
Aleutian Andreanof Arc in Alaska during September-October 2020. The 
two-dimensional (2-D) seismic survey will occur within the Exclusive

[[Page 55646]]

Economic Zone (EEZ) of the United States. The survey will use a 36-
airgun towed array with a total discharge volume of ~6,600 cubic inches 
(in\3\) (108,155 cm\3\) as an acoustic source, acquiring return signals 
using both a towed streamer as well as ocean bottom seismometers 
(OBSs).
    The study will use 2-D seismic surveying to seismically image the 
structure of the crust along and across the Andreanof segment of the 
Aleutian Arc, an intact arc segment with a simple and well known 
history. Existing geochemical analyses of igneous rocks from this 
segment suggest an along-segment trend in crustal-scale fractionation 
processes. Seismic velocity provides strong constraints on bulk 
composition, and so seismic images will reveal the constructional 
architecture, vertical fractionation patterns, and along-arc trends in 
both of those things. Together with existing observations from surface 
rocks (e.g., bulk composition, volatile content) and forcing parameters 
(e.g., slab geometry, sediment input, deformation-inferred stress 
regime), hypotheses related to controls on oceanic-arc crustal 
construction and fractionation can be tested and refined.

Dates and Duration

    The survey is expected to last for approximately 48 days, including 
approximately 16 days of seismic operations, 19 days of equipment 
deployment/retrieval, and 8 days of transits, and 5 contingency days 
(accounting for potential delays due to, e.g., weather). R/V Langseth 
will likely leave out of and return to port in Dutch Harbor, Alaska, 
during September-October 2020.

Specific Geographic Region

    The survey will occur within the area of approximately 49-53.5[deg] 
N and approximately 172.5-179[deg] W. Representative survey tracklines 
are shown in Figure 1, available online at: www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatory-marine-geophysical-survey-2. Tracklines in the vicinity of specific 
Steller sea lion haul-outs and rookeries are designed to ensure that 
the area assumed to be ensonified above the Level B harassment 
threshold (see Estimated Take section) does not extend beyond a 3,000 
ft (0.9 kilometers (km)) buffer around those areas. In addition, the 
survey vessel will not physically travel within 3 nautical miles (nmi) 
(5.5 km) of listed Steller sea lion rookeries. 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 EEZ of the United States, 
including Alaskan state waters, ranging in depth from 35-7,100 meters 
(m). Approximately 3,224 km of transect lines will be surveyed. Most of 
the survey (73 percent) would occur in deep water (>1,000 m), 26 
percent would occur in intermediate water (100-1,000 m deep), and 
approximately 1 percent would take place in shallow water <100 m deep.

Detailed Description of Specific Activity

    The procedures to be used for the survey would be similar to those 
used during previous seismic surveys by L-DEO and involve conventional 
seismic methodology. The survey will involve one source vessel, R/V 
Langseth, which is owned by NSF and operated on its behalf by L-DEO. 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 36 elements, 
including 20 Bolt 1500LL airguns with volumes of 180 to 360 in\3\ 
(2,950-5,800 cm\3\) and 16 Bolt 1900LLX airguns with volumes of 40 to 
120 in\3\ (655-1,966 cm\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 PEIS is available online 
at: www.nsf.gov/geo/oce/envcomp/usgs-nsf-marine-seismic-research/nsf-usgs-final-eis-oeis-with-appendices.pdf). The vessel speed during 
seismic operations will be approximately 4.5 knots (~8.3 km/hour) 
during the survey and the airgun array will be towed at a depth of 9 m. 
The receiving system consists of OBSs and a towed hydrophone streamer 
with a nominal length of 8 km. As the airguns are towed along the 
survey lines, the hydrophone streamer transfers the data to the on-
board processing system, and the OBSs receive and store the returning 
acoustic signals internally for later analysis.
    The study consists of one east-west strike-line transect (~540 km), 
two north-south dip-line transects (~420 km and ~285 km), connecting 
multi-channel seismic (MCS) transects (~480 km), and an MCS survey of 
the Amlia Fracture Zone (~285 km). (See Figure 1, available online.) 
The representative tracklines have a total length of 2,010 km. The 
strike- and dip-line transects will first be acquired using OBSs, which 
will be deployed along one line at a time, the line will be surveyed, 
and the OBSs will then be recovered, before moving onto the next line. 
After all refraction data is acquired, the strike and dip lines will be 
acquired a second time using MCS. The MCS transect lines and Amlia 
Fracture Zone transect lines will be acquired only once using MCS. 
Thus, the line km to be acquired during the entire survey is expected 
to be approximately 3,255 km. There could be additional seismic 
operations associated with turns, airgun testing, and repeat coverage 
of any areas where initial data quality is sub-standard, and 25 percent 
has been added to the assumed survey line-kilometers to account for 
this potential.
    For the majority of the survey (90 percent), R/V Langseth will tow 
the full array, consisting of four strings with 36 airguns (plus 4 
spares) with a total discharge volume of 6,600 in\3\. In certain 
locations (see Figure 1) closest to islands, only half the array (18 
airguns) would be operated, with a total volume of approximately 3,300 
in\3\ (54,077 cm\3\). The airguns would fire at a shot interval of 22 
seconds (s) during MCS shooting with the hydrophone streamer and at a 
120-s interval during refraction surveying to OBSs.
    The seismometers consist of short-period multi-component OBSs from 
Scripps Institution of Oceanography (SIO). Fifty OBSs will be deployed 
and subsequently retrieved by R/V Langseth prior to MCS surveying. When 
an OBS is ready to be retrieved, an acoustic release transponder 
(pinger) interrogates the instrument at a frequency of 12 kiloHertz 
(kHz); a response is received at the same frequency. The burn-wire 
release assembly is then activated, and the instrument is released from 
its 36-kilogram iron grate anchor to float to the surface. Take of 
marine mammals is not expected to occur incidental to L-DEO's use of 
OBSs.
    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. 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

[[Page 55647]]

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 proposed IHA was published in the Federal Register on 
July 28, 2020 (85 FR 45389). During the 30-day public comment period, 
NMFS received a letter from the Marine Mammal Commission (Commission). 
Please see the Commission's letter for full details regarding their 
recommendations and rationale. The letter is available online at: 
www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatory-marine-geophysical-survey-2. A summary of the 
Commission's recommendations as well as NMFS' responses is below.
    Comment--Noting certain inconsistencies and errors in information 
provided in L-DEO's application and NMFS' Federal Register notice, the 
Commission recommends that NMFS (1) determine what the percentages of 
the survey tracklines in the three depth strata should be, (2) ensure 
that the same percentages of survey tracklines are used for Level A and 
B harassment in each of the three depth strata, (3) re-estimate the 
numbers of Level A and B harassment takes accordingly, and (4) ensure 
that the total takes of low-frequency and high-frequency cetaceans and 
Level B harassment takes of mid-frequency cetaceans, otariids, and 
phocids are based on the Level A and B harassment takes added together.
    Response--As noted in the Commission's letter, L-DEO provided 
revised tables C-1 and D-1, which corrected various minor errors 
described in the Commission's letter. Of greater substance, L-DEO also 
revised the estimated take numbers to reflect the movement of certain 
tracklines to minimize impacts on areas of importance to Steller sea 
lions and sea otters, as described above (see Changes from the Proposed 
IHA below for additional discussion). Correct values representing the 
proportion of trackline in each depth stratum and associated size of 
ensonified area were used in calculating the estimated takes, and the 
total takes authorized represent the sum of estimated instances of 
Level A harassment and Level B harassment, as recommended by the 
Commission. NMFS does note that the supposed ``discrepancies'' 
referenced by the Commission regarding percentages of survey trackline 
in each depth stratum appear instead to be a misunderstanding about 
what these values represent. The values referenced by the Commission 
from revised Table C-1 are not percentages of survey trackline, but 
rather percentages of ensonified area in each depth stratum. Due to the 
large size of the estimated Level B harassment ensonified areas 
relative to the estimated Level A harassment ensonified areas, the 
percentages of ensonified area within each depth stratum will be 
different. Because the Level A harassment ensonified areas are all 
generally small, the percentages of ensonified area per depth stratum 
are essentially the same as the percentages of trackline per depth 
stratum.
    Comment--Describing what it believes to be the best available 
information regarding Steller sea lion occurrence in the survey area, 
the Commission recommends that NMFS ensure that the number of Level B 
harassment takes of Steller sea lions are correct based on a revised 
density of 0.0392 sea lions/km\2\ in shallow- and intermediate-water 
depths and the same revised percentages of survey tracklines for Level 
A and B harassment in each of the three depth strata.
    Response--NMFS concurs with the Commission's recommendation and has 
adopted it. Estimated takes of Steller sea lion have been revised in 
part through incorporation of the recommended density values.
    Comment--The Commission recommends that NMFS adjust the marine 
mammal density estimates used in estimating potential takes using 
either coefficients of variation (CVs) or standard deviations for L-
DEO's proposed survey, and reiterates a previous recommendation that 
NMFS develop a policy and consistent approach for how L-DEO and other 
NSF-affiliated entities should incorporate uncertainty in density 
estimates that have been extrapolated from other areas or during other 
times of the years or when the data themselves include high 
uncertainty.
    Response--NMFS does not concur with the Commission's recommendation 
and does not adopt it. As noted by the Commission, it has previously 
provided this same recommendation. NMFS has previously expressed its 
disagreement with the recommendation, which we reiterate here.
    The Commission states that ``[u]sing only the mean densities would 
likely result in an underestimation of takes due to the CVs being so 
much greater than the mean estimates.'' A CV simply shows the extent of 
variability in relation to the mean of the population, but does not 
indicate in which direction relative to the mean a true outcome will 
lie. The Commission does not explain why use of the mean densities 
would result in an underestimate of takes versus an overestimate of 
takes and, in fact, both outcomes should be considered equally likely. 
Therefore, the Commission's suggested approach of increasing the 
density estimate through, e.g., use of the mean plus the CV, would be 
unnecessarily precautionary. NMFS' implementing regulations state that 
NMFS should rely on the best scientific evidence available in making 
findings of negligible impact and no unmitigable adverse impact. There 
is no requirement in the MMPA or NMFS' implementing regulations to 
introduce unwarranted precaution into the analyses. While NMFS 
acknowledges that there is uncertainty associated with any density 
estimate, the take estimate methodology used here produces the most 
appropriate estimate of potential takes.
    NMFS indicated in its previous response to this comment that it is 
open to consideration of specific correction factors for use for 
specific circumstances or species in future IHAs and to further 
discussion with the Commission. However, it appears that the Commission 
misunderstood this comment as a commitment to take action. The 
Commission states in its letter that ``[i]t has been more than a year 
and NMFS has not contacted the Commission regarding this matter'' and 
that ``NMFS has yet to advance the issue.'' NMFS does not believe that 
it needs to develop a policy regarding this issue and, therefore, NMFS 
does not intend to contact the Commission or take steps to advance an 
issue that it does not believe requires action. However, NMFS 
reiterates its willingness to discuss the issue with the Commission in 
greater detail.
    Comment--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

[[Page 55648]]

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 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. NMFS will, 
however, provide an additional detailed explanation of the reasons why 
the Commission's recommendations regarding this matter are not followed 
within 120 days, as suggested by the Commission and required by section 
202 of the MMPA.
    Comment--The Commission recommends that NMFS require L-DEO to (1) 
analyze the data recorded on the OBSs 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, (2) justify why 
it did not use the maximum radii as its Level B harassment zones in 
deep water for both the 36- and 18-airgun array as it did for 
intermediate and shallow water, and (3) if the justification is 
inconsistent with the approach taken for intermediate and shallow 
water, revise the Level B harassment zones in deep water based on the 
maximum radii and re-estimate the numbers of takes accordingly.
    Response--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, perform 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. However, there are no NSF-proposed seismic 
surveys on the R/V Langseth for this region in the foreseeable future.
    The Commission also recommended that NMFS require L-DEO to justify 
why it did not use the maximum radii as its Level B harassment zones in 
deep water. L-DEO used the maximum deep-water radii to estimate the 
scaling factors discussed by the Commission, as the isopleths are not 
spherical. The highest scaling factor (2.08) is obtained for the 
maximum radii and when scaling to account for differences in towed 
depths and/or volumes between sources, L-DEO uses the highest scaling 
factor to be conservative. However, the maximum deep-water radii are 
not used for defining the Level B harassment zones in deep water, but 
rather the radii at 2,000 m depth.
    The maximum radii for the 6,600 and 3,300 in\3\ arrays are at 
depths of 10,129 m and 4,700 m, depths that are well below where marine 
mammals would be encountered. Given the sound propagation loss in 
water, the maximum radii would thus not be appropriate to define the 
Level B harassment zones. L-DEO uses the radius at a 2,000 m depth, as 
this is approximately the maximum relevant water depth for marine 
mammals. The maximum radii were used for both intermediate and shallow 
water as the water depth for these depth strata is less than 2,000 m.
    In light of this justification, NMFS determined that revising the 
Level B harassment zones in deep water based on the maximum radii is 
not appropriate, and therefore, re-estimating the numbers of takes is 
not warranted.
    Comment--The Commission recommends that NMFS include in the final 
authorization a requirement to use a method believed by the Commission 
to be appropriate for estimating the numbers of marine mammals taken, 
e.g., by applying relevant corrections to account for animals that are 
not detected.
    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 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.

[[Page 55649]]

    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.
    Comment--The Commission 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 versus nighttime hours 
(including dawn and dusk), and further recommends that NMFS require L-
DEO to include in its monitoring report all data to be collected under 
section 5(d)(ii), (iii), and (iv) through specific stipulations in 
section 6(a) of the final authorization.
    Response--NMFS concurs with the recommendation and has included 
these requirements in the IHA.
    Comment--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 but will 
consider any future requests for incidental take authorization from 
NSF-affiliated entities according to the requirements of the MMPA.
    Comment--The Commission asserts that ``only one of the last six 
monitoring reports involving geophysical surveys conducted by L-DEO and 
other NSF-affiliated entities has been posted on NMFS' website,'' and 
recommends that NMFS post all final monitoring reports on its website 
as soon as they are available.
    Response--NMFS concurs with the Commission's recommendation and it 
is our practice to post all final monitoring reports on its website as 
soon as they are available. All available monitoring reports involving 
geophysical surveys conducted by L-DEO and other NSF-affiliated 
entities are currently available on NMFS' website. We note that reports 
are not yet available for the three most recent IHAs issued for these 
activities.
    Comment--The Commission recommends that NMFS include in all draft 
and final IHAs the explicit requirements 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 deaths.
    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--The Commission recommends that NMFS refrain from issuing a 
renewal for any authorization unless it is consistent with the 
procedural requirements specified in section 101(a)(5)(D)(iii) of the 
MMPA.
    Response--In prior responses to comments about IHA Renewals (e.g., 
84 FR 52464; October 02, 2019 and 85 FR 53342; August 28, 2020), NMFS 
has explained how the Renewal process, as implemented, is consistent 
with the statutory requirements contained in section 101(a)(5)(D) of 
the MMPA and, therefore, we plan to continue to issue qualifying 
Renewals when the requirements outlined on our website are met. Thus, 
NMFS agrees with the Commission's recommendation that we should not 
issue a Renewal for any authorization unless it is consistent with the 
procedural requirements specified in section 101(a)(5)(D)(iii) of the 
MMPA. NMFS has found that the Renewal process is consistent with the 
statutory requirements of the MMPA and, further, promotes NMFS' goals 
of improving conservation of marine mammals and increasing efficiency 
in the MMPA compliance process. Therefore, we intend to continue 
implementing the Renewal process.

Changes From the Proposed IHA

    The only substantive change from the proposed IHA is the revision 
of take estimates. As noted in the notice of proposed IHA, L-DEO agreed 
to modify its originally proposed tracklines in order to avoid takes of 
sea otters (through consultation with the U.S. Fish and Wildlife 
Service) and to minimize impacts on Steller sea lions (by moving 
tracklines near specific, known sea lion rookeries such that the track 
is

[[Page 55650]]

sufficiently distant from shore that the estimated Level B harassment 
zone does not overlap with a 3,000 ft (0.9-km) buffer around these 
areas). Although L-DEO had committed to these changes at the time of 
publication of the notice of proposed IHA, take estimates had not yet 
been revised accordingly. In addition, the take estimate for Steller 
sea lions was revised through use of the adjusted density value 
recommended by the Marine Mammal Commission (as discussed above). For 
species where the take number changed, all take numbers decreased, 
except for the Steller sea lion, where the increased density value led 
to an increase in the take estimate.
    During the public review period, NMFS-affiliated scientists noted 
that a newly described species of beaked whale (Berardius minimus; 
Yamada et al., 2019) could be present in the survey area. At least five 
specimens of Sato's beaked whale have been reported from U.S. waters in 
the vicinity of the eastern Aleutian Islands, St. George Island, and 
the southern Alaska Peninsula (Morin et al., 2017). No information is 
available regarding the occurrence of this species. Therefore, NMFS has 
authorized take of one group of the species, as represented by the 
average group size of Berardius spp. from Barlow (2016).
    Finally, NMFS has included reporting requirements recommended by 
the Marine Mammal Commission (discussed above).

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; 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 
(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 Endangered 
Species Act (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).

                                               Table 1--Marine Mammals That Could Occur in the Survey Area
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      ESA/MMPA status;   Stock abundance (CV,
            Common name                  Scientific name              Stock           strategic (Y/N)      Nmin, most recent        PBR      Annual M/SI
                                                                                            \1\          abundance survey) \2\                   \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
    North Pacific right whale......  Eubalaena japonica....  Eastern North Pacific   E/D; Y             31 (0.226; 26; 2015)..         0.05            0
                                                              (ENP).
Family Eschrichtiidae:
    Gray whale.....................  Eschrichtius robustus.  ENP...................  -; N               26,960 (0.05; 25,849;           801          139
                                                                                                         2016).
                                                             Western North Pacific   E/D; Y             290 (n/a; 271; 2016...         0.12          Unk
                                                              (WNP).
Family Balaenopteridae (rorquals):
    Humpback whale.................  Megaptera novaeangliae  Central North Pacific   E/D; Y             10,103 (0.3; 7,891;              83           25
                                      kuzira.                 (CNP) *.               E/D; Y              2006).                           3          2.6
                                                             Western North Pacific                      1,107 (0.3; 865; 2006)
                                                              *.
    Minke whale....................  Balaenoptera            Alaska *..............  -; N               Unknown...............          n/a            0
                                      acutorostrata
                                      scammoni.
    Sei whale......................  B. borealis borealis..  ENP...................  E/D; Y             519 (0.4; 374; 2014)..         0.75        >=0.2
    Fin whale......................  B. physalus physalus..  Northeast Pacific *...  E/D; Y             Unknown...............          n/a          0.4
    Blue whale.....................  B. musculus musculus..  ENP...................  E/D; Y             1,496 (0.44; 1,050;         \6\ 1.2       >=19.4
                                                                                                         2014).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale....................  Physeter macrocephalus  North Pacific *.......  E/D; Y             Unknown...............          n/a          4.7
Family Ziphiidae (beaked whales):
    Cuvier's beaked whale..........  Ziphius cavirostris...  Alaska................  -; N               Unknown...............          n/a            0
    Baird's beaked whale...........  Berardius bairdii.....  Alaska................  -; N               Unknown...............          n/a            0
    Sato's beaked whale............  B. minimus............  n/a...................  -; N               Unknown...............          n/a            0
    Stejneger's beaked whale.......  Mesoplodon stejnegeri.  Alaska................  -; N               Unknown...............          n/a            0
Family Delphinidae:
    Pacific white-sided dolphin....  Lagenorhynchus          North Pacific \5\.....  -; N               26,880 (n/a; 26,880;            n/a            0
                                      obliquidens.                                                       1990).
    Northern right whale dolphin...  Lissodelphis borealis.  CA/OR/WA *............  -; N               26,556 (0.44; 18,608;           179          3.8
                                                                                                         2014).
    Risso's dolphin................  Grampus griseus.......  CA/OR/WA *............  -; N               6,336 (0.32; 4,817;              46        >=3.7
                                                                                                         2014).
    Killer whale...................  Orcinus orca \4\......  ENP Offshore..........  -; N               300 (0.1; 276; 2012)..          2.8            0

[[Page 55651]]

 
                                     ENP Gulf of Alaska,     ......................  -; N               587 (n/a; 2012).......          5.9            1
                                      Aleutian Islands, and
                                      Bering Sea Transient.
                                     ENP Alaska Resident...  ......................  -; N               2,347 (n/a; 2012).....           24            1
Family Phocoenidae (porpoises):
    Harbor porpoise................  Phocoena phocoena       Bering Sea \5\........  -; Y               48,215 (0.22; 40,150;           n/a          0.2
                                      vomerina.                                                          1999).
    Dall's porpoise................  Phocoenoides dalli      Alaska \5\............  -; N               83,400 (0.097; n/a;             n/a           38
                                      dalli.                                                             1991).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    Northern fur seal..............  Callorhinus ursinus...  Pribilof Islands/       D; Y               620,660 (0.2; 525,333;       11,295          399
                                                              Eastern Pacific.                           2016).
    Steller sea lion...............  Eumetopias jubatus      Western U.S...........  E/D; Y             53,624 (n/a; 2018)....          322          247
                                      jubatus.
Family Phocidae (earless seals):
    Harbor seal....................  Phoca vitulina          Aleutian Islands......  -; N               5,588 (n/a; 5,366;               97           90
                                      richardii.                                                         2018).
    Spotted seal...................  P. largha.............  Alaska *..............  -; N               461,625 (n/a; 423,237;       12,697          329
                                                                                                         2013).
    Ribbon seal....................  Histriophoca fasciata.  Alaska *..............  -; N               184,697 (n/a; 163,086;        9,785          3.9
                                                                                                         2013).
    Northern elephant seal.........  Mirounga                California Breeding...  -; N               179,000 (n/a; 81,368;         4,882          8.8
                                      angustirostris.                                                    2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Stocks marked with an asterisk were addressed in further detail in the notice of proposed IHA.
\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 at: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is
  coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable. For most stocks of killer whales, the
  abundance values represent direct counts of individually identifiable animals; therefore there is only a single abundance estimate with no associated
  CV. For certain stocks of pinnipeds, abundance estimates are based upon observations of animals (often pups) ashore multiplied by some correction
  factor derived from knowledge of the species' (or similar species') life history to arrive at a best abundance estimate; therefore, there is no
  associated CV. In these cases, the minimum abundance may represent actual counts of all animals ashore.
\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, subsistence hunting, ship strike). Annual mortality/serious injury (M/SI) often cannot be determined precisely and is in some
  cases presented as a minimum value. All M/SI values are as presented in the 2019 SARs.
\4\ Transient and resident killer whales are considered unnamed subspecies (Committee on Taxonomy, 2020).
\5\ Abundance estimates for these stocks are not considered current. PBR is therefore considered undetermined for these stocks, as there is no current
  minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as these represent the best available
  information for use in this document.
\6\ This stock is known to spend a portion of time outside the U.S. EEZ. Therefore, the PBR presented here is the allocation for U.S. waters only and is
  a portion of the total. The total PBR for blue whales is 2.1 (7/12 allocation for U.S. waters). Annual M/SI presented for these species is for U.S.
  waters only.

    Prior to 2016, humpback whales were listed under the ESA as an 
endangered species worldwide. Following a 2015 global status review 
(Bettridge et al., 2015), NMFS established 14 distinct population 
segments (DPS) with different listing statuses (81 FR 62259; September 
8, 2016) pursuant to the ESA. The DPSs that occur in U.S. waters do not 
necessarily equate to the existing stocks designated under the MMPA and 
shown in Table 1.
    Within Alaska waters, four current humpback whale DPSs may occur: 
The Western North Pacific (WNP) DPS (endangered), Hawaii DPS (not 
listed), Mexico DPS (threatened), and Central America DPS (endangered). 
Two humpback whale stocks designated under the MMPA may occur within 
Alaskan waters: The Western North Pacific Stock and the Central North 
Pacific Stock. Both these stocks are designated as depleted under the 
MMPA. According to Wade (2017), in the Aleutian Islands and Bering, 
Chukchi, and Beaufort Seas, encountered whales are most likely to be 
from the Hawaii DPS (86.8 percent), but could be from the Mexico DPS 
(11 percent) or WNP DPS (2.1 percent). Note that these probabilities 
reflect the upper limit of the 95 percent confidence interval of the 
probability of occurrence; therefore, numbers may not sum to 100 
percent for a given area.
    Additional detailed information regarding the potentially affected 
stocks of marine mammals was provided in the notice of proposed IHA (85 
FR 45389; July 28, 2020). No new information is available, and we do 
not reprint that discussion here. Please see the notice of proposed IHA 
for additional information.

Biologically Important Areas (BIA)

    Several biologically important areas for marine mammals are 
recognized in the Bering Sea, Aleutian Islands, and Gulf of Alaska. 
Critical habitat is designated for the Steller sea lion (58 FR 45269; 
August 27, 1993). Critical habitat is defined by section 3 of the ESA 
as (1) the specific areas within the geographical area occupied by the 
species, at the time it is listed, on which are found those physical or 
biological features (a) essential to the conservation of the species 
and (b) which may require special management considerations or 
protection; and (2) specific areas outside the geographical area 
occupied by the species at the time it is listed, upon a determination 
by the Secretary that such areas are essential for the conservation of 
the species.
    Designated Steller sea lion critical habitat includes terrestrial, 
aquatic, and air zones that extend 3,000 ft (0.9 km) landward, seaward, 
and above each major rookery and major haulout in Alaska. For the 
Western DPS, the aquatic zone extends further, out 20 nmi (37 km) 
seaward of major rookeries and haulouts west of 144[ordm] W. In 
addition to major rookeries and haulouts, critical habitat foraging 
areas have been designated in Seguam Pass, Bogoslof area, and Shelikof 
Strait. Of the foraging areas, only Seguam Pass overlaps the

[[Page 55652]]

proposed survey area. The Bogoslof foraging area is located to the east 
of the survey area, and Shelikof Strait is in the western Gulf of 
Alaska. In addition, ``no approach'' buffer areas around rookery sites 
of the Western DPS of Steller sea lions are identified. ``No approach'' 
zones are restricted areas wherein no vessel may approach within 3 nmi 
(5.6 km) of listed rookeries; some of these are adjacent to the survey 
area. In the Aleutian Islands, critical habitat includes 66 sites (26 
rookeries and 40 haulout sites) and foraging areas in Seguam Pass 
(within the proposed survey area) and the Bogoslof area (east of the 
survey area). Please see Figure 1 of L-DEO's application for additional 
detail.
    Critical habitat has also been designated for the North Pacific 
right whale (73 FR 19000; April 8, 2008). The designation includes 
areas in the Bering Sea and Gulf of Alaska. However, the closest 
critical habitat unit, in the Bering Sea, is more than 400 km away from 
the proposed survey area. There is no critical habitat designated for 
any other species within the region. In addition, a feeding BIA for 
right whales is recognized to the south of Kodiak Island, and the 
Bering Sea critical habitat unit is also recognized as a BIA.
    For fin whales, a BIA for feeding is recognized in Shelikof Strait, 
between Kodiak Island and the Alaska Peninsula, and extending west to 
the Semidi Islands. For gray whales, a feeding BIA is recognized to the 
south of Kodiak Island, and a migratory BIA is recognized as extending 
along the continental shelf throughout the Gulf of Alaska, through 
Unimak Pass in the eastern Aleutian Islands, and along the Bering Sea 
continental shelf. For humpback whales, feeding BIAs are recognized 
around the Shumagin Islands and around Kodiak Island. These areas are 
sufficiently distant from the proposed survey area that no effects to 
important behaviors occurring in the BIAs should be expected. Moreover, 
the timeframe of the planned survey does not overlap with expected 
highest abundance of whales on the feeding BIAs or with gray whale 
migratory periods.
    A separate feeding BIA is recognized in the Bering Sea for fin 
whales. Because the distribution of presumed feeding fin whales in the 
Bering Sea is widespread, a wide region from the Middle Shelf domain to 
the slope is considered to be a BIA. The highest densities of feeding 
fin whales in the Bering Sea likely occur from June through September. 
The BIA is considered as being in waters shallower than the 1,000-m 
isobath on the eastern Bering Sea shelf, and does not extend past 
approximately Unimak Pass in the Aleutian Islands. A gray whale feeding 
BIA is recognized along the north side of the Alaska Peninsula. Marine 
mammal behavior in these BIAs is similarly not expected to be affected 
by the proposed survey due to distance and timing.
    Large aggregations of feeding humpback whales have historically 
been observed along the northern side of the eastern Aleutian Islands 
and Alaska Peninsula, and a feeding BIA is recognized. Highest 
densities are expected from June through September. The eastern edge of 
the planned survey area is approximately 100 km west of the western 
edge of the recognized BIA, but it is possible that the survey could 
affect feeding humpback whales. For more information on BIAs, please 
see Ferguson et al. (2015a, 2015b).

Unusual Mortality Events (UME)

    A UME is defined under the MMPA as ``a stranding that is 
unexpected; involves a significant die-off of any marine mammal 
population; and demands immediate response.'' For more information on 
UMEs, please visit: www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-unusual-mortality-events. Currently recognized 
UMEs in Alaska involving species under NMFS' jurisdiction include those 
affecting ice seals in the Bering and Chukchi Seas and gray whales. 
Since June 1, 2018, elevated strandings for bearded, ringed and spotted 
seals have occurred in the Bering and Chukchi seas in Alaska, with 
causes undetermined. For more information, please visit: 
www.fisheries.noaa.gov/alaska/marine-life-distress/2018-2020-ice-seal-unusual-mortality-event-alaska.
    Since January 1, 2019, elevated gray whale strandings have occurred 
along the west coast of North America from Mexico through Alaska. As of 
June 5, 2020, there have been a total of 340 whales reported in the 
event, with approximately 168 dead whales in Mexico, 159 whales in the 
United States (53 in California; 9 in Oregon; 42 in Washington, 55 in 
Alaska), and 13 whales in British Columbia, Canada. For the United 
States, the historical 18-year 5-month average (Jan-May) is 14.8 whales 
for the four states for this same time-period. Several dead whales have 
been emaciated with moderate to heavy whale lice (cyamid) loads. 
Necropsies have been conducted on a subset of whales with additional 
findings of vessel strike in three whales and entanglement in one 
whale. In Mexico, 50-55 percent of the free-ranging whales observed in 
the lagoons in winter have been reported as ``skinny'' compared to the 
annual average of 10-12 percent ``skinny'' whales normally seen. The 
cause of the UME is as yet undetermined. For more information, please 
visit: www.fisheries.noaa.gov/national/marine-life-distress/2019-2020-gray-whale-unusual-mortality-event-along-west-coast-and.
    Another recent, notable UME involved large whales and occurred in 
the western Gulf of Alaska and off of British Columbia, Canada. 
Beginning in May 2015, elevated large whale mortalities (primarily fin 
and humpback whales) occurred in the areas around Kodiak Island, 
Afognak Island, Chirikof Island, the Semidi Islands, and the southern 
shoreline of the Alaska Peninsula. Although most carcasses have been 
non-retrievable as they were discovered floating and in a state of 
moderate to severe decomposition, the UME is likely attributable to 
ecological factors, i.e., the 2015 El Ni[ntilde]o, ``warm water blob,'' 
and the Pacific Coast domoic acid bloom. The UME was closed in 2016. 
More information is available online at www.fisheries.noaa.gov/national/marine-life-distress/2015-2016-large-whale-unusual-mortality-event-western-gulf-alaska.

Marine Mammal Hearing

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

[[Page 55653]]

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

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Twenty-four marine mammal species (18 cetacean and six pinniped (two 
otariid and four phocid) species) are considered herein. Of the 
cetacean species that may be present, seven are classified as low-
frequency cetaceans (i.e., all mysticete species), nine are classified 
as mid-frequency cetaceans (i.e., all delphinid and ziphiid species and 
the sperm whale), and two are classified as high-frequency cetaceans 
(i.e., porpoises).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    Detailed descriptions of the potential effects of similar specified 
activities have been provided in other recent Federal Register notices, 
including for activities occurring within the same specified 
geographical region (e.g., 83 FR 29212, June 22, 2018; 84 FR 14200, 
April 9, 2019; 85 FR 19580, April 7, 2020). Section 7 of L-DEO's 
application provides a comprehensive discussion of the potential 
effects of the proposed survey. We have reviewed L-DEO's application 
and believe it is accurate and complete. No significant new information 
is available. The information in L-DEO's application and in the 
referenced Federal Register notices are sufficient to inform our 
determinations regarding the potential effects of L-DEO's specified 
activity on marine mammals and their habitat. We refer the reader to 
these documents rather than repeating the information here. 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 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 
potential effects of the specified activity, 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 this proposal inasmuch as the information is relevant to the 
specified activity and to a discussion of the potential effects of the 
specified activity on marine mammals found later in this document. 
Please see that document (85 FR 45389; July 28, 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 the 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 are primarily 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). 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

[[Page 55654]]

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 numbers.

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 permanent threshold shift (PTS) of some degree (equated to 
Level A harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). NMFS uses a generalized acoustic threshold based 
on received level to estimate the onset of behavioral harassment. NMFS 
predicts that marine mammals may be behaviorally harassed (i.e., Level 
B harassment) when exposed to underwater anthropogenic noise above a 
received level of 160 dB re 1 microPascal ([mu]Pa) root mean square 
(rms) for the impulsive source (i.e., seismic airguns) evaluated here.
    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 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 
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 feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and acoustic 
propagation modeling.
    L-DEO's modeling methodologies are described in greater detail in 
Appendix A of L-DEO's IHA application. The survey would acquire data 
using the 36-airgun array with a total discharge volume of 6,600 in\3\ 
at a maximum tow depth of 9 m. During approximately 10 percent of the 
planned survey tracklines, the array would be used at half the total 
volume (i.e., an 18-airgun array with total volume of 3,300 in\3\). L-
DEO's modeling approach uses ray tracing for the direct wave traveling 
from the array to the receiver and its associated source ghost 
(reflection at the air-water interface in the vicinity of the array), 
in a constant-velocity half-space (infinite homogeneous ocean layer, 
unbounded by a seafloor). To validate the model results, L-DEO measured 
propagation of pulses from the 36-airgun array at a tow depth of 6 m in 
the Gulf of Mexico, for deep water (1,600 m), intermediate water depth 
on the slope (600-1,100 m), and shallow water (50 m) (Tolstoy et al., 
2009; Diebold et al., 2010).
    L-DEO collected a MCS data set from R/V Langseth on an 8 km 
streamer in 2012 on the shelf of the Cascadia Margin off of Washington 
in water up to 200 m deep that allowed Crone et al. (2014) to analyze 
the hydrophone streamer (>1,100 individual shots). These empirical data 
were then analyzed to determine in situ sound levels for shallow and 
upper intermediate water depths. These data suggest that modeled radii 
were 2-3 times larger than the measured radii in shallow water. 
Similarly, data collected by Crone et al. (2017) during a survey off 
New Jersey in 2014 and 2015 confirmed that in situ measurements 
collected by R/V Langseth hydrophone streamer were 2-3 times smaller 
than the predicted radii.
    L-DEO model results are used to determine the assumed radial 
distance to the 160-dB rms threshold for these arrays 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 7,100 m, but marine mammals in the region 
are generally not anticipated to dive below 2,000 m (Costa and 
Williams, 1999). For the 36-airgun array, the estimated radial distance 
for intermediate (100-1,000 m) and shallow (<100 m) water depths is 
taken from Crone et al. (2014). L-DEO typically derives estimated 
distances for intermediate water depths by applying a correction factor 
of 1.5 to the model results for deep water. The Crone et al.

[[Page 55655]]

(2014) empirical data produce results consistent with L-DEO's typical 
approach (8,233 m versus 8,444 m). For the 18-airgun array, the radii 
for shallow and intermediate-water depths are taken from Crone et al. 
(2014) and scaled to account for the difference in airgun volume.
    The estimated distances to the Level B harassment isopleths for the 
arrays are shown in Table 4.

         Table 4--Predicted Radial Distances to Isopleths Corresponding to Level B Harassment Threshold
----------------------------------------------------------------------------------------------------------------
                                                                                                      Level B
                        Source and volume                          Tow depth (m)    Water depth     harassment
                                                                                        (m)          zone (m)
----------------------------------------------------------------------------------------------------------------
36 airgun array; 6,600 in \3\...................................               9          >1,000       \1\ 5,629
                                                                                       100-1,000       \3\ 8,233
                                                                                            <100      \3\ 11,000
18 airgun array; 3,300 in \3\...................................               9          >1,000       \1\ 3,562
                                                                                       100-1,000       \2\ 3,939
                                                                                            <100       \2\ 5,263
----------------------------------------------------------------------------------------------------------------
\1\ Distance based on L-DEO model results.
\2\ Based on empirical data from Crone et al. (2014) with scaling factor based on deep-water modeling applied to
  account for differences in array size.
\3\ Based on empirical 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 sound pressure level 
(SPL) for the Langseth airgun arrays were derived from calculating the 
modified far-field signature. 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 estimating Level B harassment distances 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.
    In order to more realistically incorporate the Technical Guidance's 
weighting functions over the seismic array's full acoustic band, 
unweighted spectrum data for the Langseth's airgun array (modeled in 1 
Hz bands) were used to make adjustments (dB) to the unweighted spectrum 
levels, by frequency, according to the weighting functions for each 
relevant marine mammal hearing group. These adjusted/weighted spectrum 
levels were then converted to pressures ([mu]Pa) in order to integrate 
them over the entire broadband spectrum, resulting in broadband 
weighted source levels by hearing group that could be directly 
incorporated within the User Spreadsheet (i.e., to override the 
Spreadsheet's more simple weighting factor adjustment). Using the User 
Spreadsheet's ``safe distance'' methodology for mobile sources 
(described by Sivle et al., 2014) with the hearing group-specific 
weighted source levels, and inputs assuming spherical spreading 
propagation and source velocities and shot intervals specific to the 
planned survey, potential radial distances to auditory injury zones 
were then calculated for SELcum thresholds.
    Inputs to the User Spreadsheet in the form of estimated source 
levels are shown in Appendix A of L-DEO's application. User 
Spreadsheets used by L-DEO to estimate distances to Level A harassment 
isopleths for the airgun arrays are also provided in Appendix A of the 
application. Outputs from the User Spreadsheets in the form of 
estimated distances to Level A harassment isopleths for the survey are 
shown in Table 5. As described above, NMFS considers onset of PTS 
(Level A harassment) to have occurred when either one of the dual 
metrics (SELcum

[[Page 55656]]

and Peak SPLflat) is exceeded (i.e., metric resulting in the 
largest isopleth).

                            Table 5--Modeled Radial Distances (m) to Isopleths Corresponding to Level A Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                    Level A harassment zone (m)
             Source (volume)                         Threshold           -------------------------------------------------------------------------------
                                                                           LF cetaceans    MF cetaceans    HF cetaceans       Phocids        Otariids
--------------------------------------------------------------------------------------------------------------------------------------------------------
36-airgun array (6,600 in\3\)...........  SELcum........................             376               0               1              10               0
                                          Peak..........................              39              14             229              42              11
18-airgun array (3,300 in\3\)...........  SELcum........................              55               0               0               2               0
                                          Peak..........................              23              11             119              25              10
--------------------------------------------------------------------------------------------------------------------------------------------------------

    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 (all estimated zones less than 15 m for 
mid-frequency cetaceans and otariid pinnipeds, up to a maximum of 42 m 
for phocid pinnipeds), 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 peak isopleth distances would in all 
cases be expected to be within the near-field of the array where the 
definition of source level breaks down. Therefore, actual locations 
within this distance of the array center where the sound level exceeds 
peak SPL isopleth distances 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. We provided 
additional discussion and quantitative support for this theoretical 
argument in the notice of proposed IHA. Please see that notice (85 FR 
45389; July 28, 2020) for additional information.
    In consideration of the received sound levels in the near-field as 
described above, we expect the potential for Level A harassment of mid-
frequency cetaceans, otariid pinnipeds, and phocid pinnipeds to be de 
minimis, even before the likely moderating effects of aversion and/or 
other compensatory behaviors (e.g., Nachtigall et al., 2018) are 
considered. We do not believe that Level A harassment is a likely 
outcome for any mid-frequency cetacean, otariid pinniped, or phocid 
pinniped and do not propose to authorize any Level A harassment for 
these species. Any estimated exposures above Level A harassment 
criteria are assumed to be takes by Level B harassment instead (see 
Table 6).

Marine Mammal Occurrence

    Information about the presence, density, and group dynamics of 
marine mammals that informs the take calculations was provided in our 
notice of proposed IHA (85 FR 45389; July 28, 2020). That information 
is not re-printed here. For additional detail, please see the proposed 
IHA notice and Appendix B of L-DEO's application. Density values are 
provided in Table B-1 of L-DEO's application. No 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.
    The Marine Mammal Commission noted several concerns with the 
density values used for Steller sea lions. As noted by the Commission, 
L-DEO used data from Department of the Navy (2014), which relied on 
abundance estimates from the 2008 stock assessment report divided by an 
area. The Commission raised the following issues: (1) Abundance 
estimates have increased since the 2008 SAR and the original estimates 
were based on portions of the eastern stock of Steller sea lions that 
would not occur in L-DEO's survey area; (2) the density value should be 
corrected on the basis of telemetry data, as done in Department of the 
Navy (2019); and (3) true density estimates may be even greater in 
shallow waters near critical habitat areas. For these reasons, the 
Commission recommended use of a corrected, revised density value of 
0.0392 sea lions/km\2\ in shallow- and intermediate-water depths, while 
retaining the estimate of 0.0098 sea lions/km\2\ in deep water. NMFS 
concurred with the recommendation and the take calculations for 
shallow- and intermediate-water depths were revised accordingly.
    In addition, as described in Changes from the Proposed IHA, NMFS 
was made aware of the potential occurrence of Sato's beaked whale (a 
newly described species previously considered to be a conspecific form 
of Baird's beaked whale) in the survey area and added a nominal amount 
of take in the form of one mean group size. This inclusion likely 
represents an overestimate of actual take, as occurrence of Sato's 
beaked whale would have been accounted for in the existing density 
estimates for Baird's beaked whale. However, we determined it 
appropriate to acknowledge the presence and potential exposure of this 
new species.

[[Page 55657]]

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. In order to estimate 
the number of marine mammals predicted to be exposed to sound levels 
that would result in Level A or Level B harassment, radial distances 
from the airgun array to predicted isopleths corresponding to the Level 
A harassment and Level B harassment thresholds are calculated, as 
described above. Those radial distances are then used to calculate the 
area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the Level A and Level B harassment thresholds. The 
distance for the 160-dB threshold (based on L-DEO model results) was 
used to draw a buffer around every transect line in a geographic 
information system (GIS) to determine the total ensonified area in each 
depth category. Estimated incidents of exposure above Level A and Level 
B harassment criteria are presented in Table 6. As noted previously, L-
DEO has added 25 percent in the form of operational days, which is 
equivalent to adding 25 percent to the proposed line-kms to be 
surveyed. This accounts for the possibility that additional operational 
days are required, but likely results in an overestimate of actual 
exposures.
    The estimated marine mammal exposures above harassment thresholds 
are generally assumed here to equate to take, and the estimates form 
the basis for our take authorization numbers. For the species for which 
NMFS does not expect there to be a reasonable potential for take by 
Level A harassment to occur, i.e., mid-frequency cetaceans and all 
pinnipeds, the estimated exposures above Level A harassment thresholds 
have been added to the estimated exposures above the Level B harassment 
threshold to produce a total number of incidents of take by Level B 
harassment that is authorized. Estimated exposures and authorized take 
numbers are shown in Table 6. Regarding humpback whale take numbers, we 
assume that whales encountered will follow Wade (2017), i.e., that 86.8 
percent of takes would accrue to the Hawaii DPS, 11 percent to the 
Mexico DPS, and 2.1 percent to the WNP DPS. Of the estimated take of 
gray whales, we assume that 1.1 percent of encountered whales would be 
from the WNP stock (Carretta et al., 2019) and authorize take 
accordingly.
    Importantly, as described in the Changes from the Proposed IHA 
section, revised take numbers have been produced after accounting for 
modification of planned tracklines to avoid take of sea otters and to 
maintain a larger buffer around specific Steller sea lion haul-outs and 
rookeries. Aside from the change to Steller sea lion density in 
shallow- and intermediate-depth waters and the addition of take of 
Sato's beaked whale, all changes to take numbers from the notice of 
proposed IHA result from revised calculations accounting for these 
shifts in planned tracklines.

                                Table 6--Estimated Taking by Level A and Level B Harassment, and Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Estimated    Estimated    Authorized   Authorized
                  Species                              Stock \1\              Level A      Level B      Level A      Level B     Total take   Percent of
                                                                             harassment   harassment   harassment   harassment                stock \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Pacific right whale \2\..............  .............................            0            0            0            2            2          6.5
Humpback whale.............................  WNP..........................          106        1,842          106        1,842        1,948        176.0
                                             CNP..........................  ...........  ...........  ...........  ...........  ...........         19.3
Blue whale.................................  .............................            2           23            2           23           25          1.7
Fin whale \5\..............................  .............................          104        1,650          104        1,650        1,754          n/a
Sei whale..................................  .............................            0            5            0            5            5          1.0
Minke whale \5\............................  .............................            2           27            2           27           29          n/a
Gray whale.................................  ENP..........................            1           61            1           61           62          0.2
                                             WNP..........................            0            1            0            1            1          0.3
Sperm whale \5\............................  .............................            0           43            0           43           43          n/a
Baird's beaked whale \5\...................  .............................            0           24            0           24           24          n/a
Sato's beaked whale \5\....................  .............................  ...........  ...........            0            9            9          n/a
Stejneger's beaked whale 3 5...............  .............................            0           47            0           47           47          n/a
Cuvier's beaked whale \5\..................  .............................            0          106            0          106          106          n/a
Pacific white-sided dolphin................  .............................            2        1,000            0        1,002        1,002          3.7
Northern right whale dolphin \3\...........  .............................  ...........  ...........            0           58           58          0.2
Risso's dolphin \3\........................  .............................            0            0            0           22           22          0.3
Killer whale...............................  Offshore.....................            0          141            0          141          141         47.0
                                             Transient....................  ...........  ...........  ...........  ...........  ...........         24.0
                                             Resident.....................  ...........  ...........  ...........  ...........  ...........          6.0
Dall's porpoise............................  .............................          157        4,312          157        4,312        4,469          5.4
Harbor porpoise............................  .............................           23          679           23          679          702          1.5
Northern fur seal..........................  .............................            1          788            0          789          789          0.1
Steller sea lion...........................  .............................            2          907            0          909          909          1.7
Northern elephant seal.....................  .............................            1          105            0          106          106          0.1
Harbor seal................................  .............................            1          148            0          149          149          2.7
Spotted seal \4\...........................  .............................  ...........  ...........            0            5            5          0.0
Ribbon seal \4\............................  .............................  ...........  ...........            0            5            5          0.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ 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 takes occurred within each stock. Where necessary, additional discussion is provided in the ``Small Numbers Analysis'' section.
\2\ In the notice of proposed IHA, estimated exposure of one whale was increased to group size of two (Shelden et al., 2005; Waite et al., 2003; Wade et
  al., 2011). Following revision of the take estimates, no exposures of North Pacific right whale are predicted. We retain the take number, reflecting
  potential exposure of one group of two whales.
\3\ L-DEO requested authorization of northern right whale dolphin take equivalent to exposure of one group. In the notice of proposed IHA, estimated
  exposure of one Risso's dolphin was increased to group size of 22. Following revision of the take estimates, no exposures of Risso's dolphin are
  predicted. We retain the take number, reflecting potential exposure of one group of 22 dolphins. Take of Sato's beaked whale reflects mean group size
  information for Baird's beaked whale. Group sizes for these species follow Barlow (2016).
\4\ L-DEO requested authorization of five takes each of spotted seal and ribbon seal.
\5\ As noted in Table 1, there is no estimate of abundance available for these species.


[[Page 55658]]

Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    As described previously, L-DEO agreed to modify certain tracklines 
in order to reduce the number and intensity of acoustic exposures of 
Steller sea lions in waters around the specific haul-outs and rookeries 
of greatest importance for the stock. Tracklines were modified to 
ensure that the vessel maintains a standoff distance sufficient to 
prevent the assumed Level B harassment zone from overlapping with a 
3,000-ft (0.9-km) buffer around those haul-outs and rookeries.

Vessel-Based Visual Mitigation Monitoring

    Visual monitoring requires the use of trained observers (herein 
referred to as visual protected species observers (PSO)) to scan the 
ocean surface 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 a 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 PSOs. The PSOs 
must have no tasks other than to conduct observational effort, record 
observational data, and communicate with and instruct relevant vessel 
crew with regard to the presence of marine mammals and mitigation 
requirements. PSO resumes shall be provided to NMFS for approval.
    At least one of the visual and two of the acoustic PSOs (discussed 
below) aboard the vessel must have a minimum of 90 days at-sea 
experience working in those roles, respectively, with no more than 18 
months elapsed since the conclusion of the at-sea experience. One 
visual PSO with such experience shall be designated as the lead for the 
entire protected species observation team. The lead PSO shall serve as 
primary point of contact for the vessel operator and ensure all PSO 
requirements per the IHA are met. To the maximum extent practicable, 
the experienced PSOs should be scheduled to be on duty with those PSOs 
with appropriate training but who have not yet gained relevant 
experience.
    During survey operations (e.g., any day on which use of the 
acoustic source is planned to occur, and whenever the acoustic source 
is in the water, whether activated or not), a minimum of two visual 
PSOs must be on duty and conducting visual observations at all times 
during daylight hours (i.e., from 30 minutes prior to sunrise through 
30 minutes following sunset). Visual monitoring of the exclusion and 
buffer zones must begin no less than 30 minutes prior to ramp-up and 
must continue until one hour after use of the acoustic source ceases or 
until 30 minutes past sunset. Visual PSOs shall coordinate to ensure 
360[deg] visual coverage around the vessel from the most appropriate 
observation posts, and shall conduct visual observations using 
binoculars and the naked eye while free from distractions and in a 
consistent, systematic, and diligent manner.
    PSOs shall establish and monitor the exclusion and buffer zones. 
These zones shall be based upon the radial distance from the edges of 
the acoustic source (rather than being based on the center of the array 
or around the vessel itself). During use of the acoustic source (i.e., 
anytime airguns are active, including ramp-up), detections of marine 
mammals within the buffer zone (but outside the exclusion zone) shall 
be communicated to the operator to prepare for the potential shutdown 
of the acoustic source.
    During use of the airgun (i.e., anytime the acoustic source is 
active, including ramp-up), detections of marine mammals within the 
buffer zone (but outside the exclusion zone) should be communicated to 
the operator to prepare for the potential shutdown of the acoustic 
source. Visual PSOs will immediately communicate all observations to 
the on duty acoustic PSO(s), including any determination by the PSO 
regarding species identification, distance, and bearing and the degree 
of confidence in the determination. Any observations of marine mammals 
by crew members shall be relayed to the PSO team. During good 
conditions (e.g., daylight hours; Beaufort sea state (BSS) 3 or less), 
visual PSOs shall conduct observations when the acoustic source is not 
operating for comparison of sighting rates and

[[Page 55659]]

behavior with and without use of the acoustic source and between 
acquisition periods, to the maximum extent practicable.
    Visual PSOs may be on watch for a maximum of four consecutive hours 
followed by a break of at least one hour between watches and may 
conduct a maximum of 12 hours of observation per 24-hour period. 
Combined observational duties (visual and acoustic but not at same 
time) may not exceed 12 hours per 24-hour period for any individual 
PSO.

Passive Acoustic Monitoring

    Acoustic monitoring means the use of trained personnel (sometimes 
referred to as passive acoustic monitoring (PAM) operators, herein 
referred to as acoustic PSOs) to operate PAM equipment to acoustically 
detect the presence of marine mammals. Acoustic monitoring involves 
acoustically detecting marine mammals regardless of distance from the 
source, as localization of animals may not always be possible. Acoustic 
monitoring is intended to further support visual monitoring (during 
daylight hours) in maintaining an exclusion zone around the sound 
source that is clear of marine mammals. In cases where visual 
monitoring is not effective (e.g., due to weather, nighttime), acoustic 
monitoring may be used to allow certain activities to occur, as further 
detailed below.
    PAM would take place in addition to the visual monitoring program. 
Visual monitoring typically is not effective during periods of poor 
visibility or at night, and even with good visibility, is unable to 
detect marine mammals when they are below the surface or beyond visual 
range. Acoustic monitoring can be used in addition to visual 
observations to improve detection, identification, and localization of 
cetaceans. The acoustic monitoring would serve to alert visual PSOs (if 
on duty) when vocalizing cetaceans are detected. It is only useful when 
marine mammals call, but it can be effective either by day or by night, 
and does not depend on good visibility. It would be monitored in real 
time so that the visual observers can be advised when cetaceans are 
detected.
    The R/V Langseth will use a towed PAM system, which must be 
monitored by at a minimum one on duty acoustic PSO beginning at least 
30 minutes prior to ramp-up and at all times during use of the acoustic 
source. Acoustic PSOs may be on watch for a maximum of four consecutive 
hours followed by a break of at least one hour between watches and may 
conduct a maximum of 12 hours of observation per 24-hour period. 
Combined observational duties (acoustic and visual but not at same 
time) may not exceed 12 hours per 24-hour period for any individual 
PSO.
    Survey activity may continue for 30 minutes when the PAM system 
malfunctions or is damaged, while the PAM operator diagnoses the issue. 
If the diagnosis indicates that the PAM system must be repaired to 
solve the problem, operations may continue for an additional five hours 
without acoustic monitoring during daylight hours only under the 
following conditions:
     Sea state is less than or equal to Beaufort sea state 
(BSS) 4;
     No marine mammals (excluding delphinids) detected solely 
by PAM in the applicable exclusion zone in the previous two hours;
     NMFS is notified via email as soon as practicable with the 
time and location in which operations began occurring without an active 
PAM system; and
     Operations with an active acoustic source, but without an 
operating PAM system, do not exceed a cumulative total of 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 will establish a minimum EZ with a 500-m 
radius. The 500-m EZ is 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 will be shut down.
    The 500-m EZ is intended to be precautionary in the sense that it 
would be expected to contain sound exceeding the injury criteria for 
all cetacean hearing groups, (based on the dual criteria of 
SELcum and peak SPL), while also providing a consistent, 
reasonably observable zone within which PSOs would typically be able to 
conduct effective observational effort. Additionally, a 500-m EZ is 
expected to minimize the likelihood that marine mammals will be exposed 
to levels likely to result in more severe behavioral responses. 
Although significantly greater distances may be observed from an 
elevated platform under good conditions, we believe that 500 m is 
likely regularly attainable for PSOs using the naked eye during typical 
conditions.
    An extended EZ of 1,500 m must be enforced for all beaked whales. 
No buffer of this extended EZ is required.

Pre-Clearance and Ramp-Up

    Ramp-up (sometimes referred to as ``soft start'') means the gradual 
and systematic increase of emitted sound levels from an airgun array. 
Ramp-up begins by first activating a single airgun of the smallest 
volume, followed by doubling the number of active elements in stages 
until the full complement of an array's airguns are active. Each stage 
should be approximately the same duration, and the total duration 
should not be less than approximately 20 minutes. The intent of pre-
clearance observation (30 minutes) is to ensure no protected species 
are observed within the buffer zone prior to the beginning of ramp-up. 
During pre-clearance is the only time observations of protected species 
in the buffer zone would prevent operations (i.e., the beginning of 
ramp-up). The intent of ramp-up is to warn protected species of pending 
seismic operations and to allow sufficient time for those animals to 
leave the immediate vicinity. A ramp-up procedure, involving a step-
wise increase in the number of airguns firing and total array volume 
until all operational airguns are activated and the full volume is 
achieved, is required at all times as part of the activation of the 
acoustic source. All operators must adhere to the following pre-
clearance and ramp-up requirements:
     The operator must notify a designated PSO of the planned 
start of ramp-up as agreed upon with the lead PSO; the notification 
time should not be less than 60 minutes prior to the planned ramp-up in 
order to allow the PSOs time to monitor the exclusion and buffer zones 
for 30 minutes prior to the initiation of ramp-up (pre-clearance);
     Ramp-ups shall be scheduled so as to minimize the time 
spent with the source activated prior to reaching the designated run-
in;
     One of the PSOs conducting pre-clearance observations must 
be notified again immediately prior to initiating ramp-up procedures 
and the operator must receive confirmation from the PSO to proceed;
     Ramp-up may not be initiated if any marine mammal is 
within the applicable exclusion or buffer zone. If a marine mammal is 
observed within the applicable exclusion zone or the buffer zone during 
the 30 minute pre-clearance period, ramp-up may not begin until the 
animal(s) has been observed exiting the zones or until an additional 
time period has elapsed with no further sightings (15 minutes for small 
odontocetes and

[[Page 55660]]

pinnipeds, and 30 minutes for all mysticetes and all other odontocetes, 
including sperm whales, beaked whales, and large delphinids, such as 
killer whales and Risso's dolphins);
     Ramp-up shall begin by activating a single airgun of the 
smallest volume in the array and shall continue in stages by doubling 
the number of active elements at the commencement of each stage, with 
each stage of approximately the same duration. Duration shall not be 
less than 20 minutes. The operator must provide information to the PSO 
documenting that appropriate procedures were followed;
     PSOs must monitor the exclusion and buffer zones during 
ramp-up, and ramp-up must cease and the source must be shut down upon 
detection of a marine mammal within the applicable exclusion zone. Once 
ramp-up has begun, detections of marine mammals within the buffer zone 
do not require shutdown, but such observation shall be communicated to 
the operator to prepare for the potential shutdown;
     Ramp-up may occur at times of poor visibility, including 
nighttime, if appropriate acoustic monitoring has occurred with no 
detections in the 30 minutes prior to beginning ramp-up. Acoustic 
source activation may only occur at times of poor visibility where 
operational planning cannot reasonably avoid such circumstances;
     If the acoustic source is shut down for brief periods 
(i.e., less than 30 minutes) for reasons other than that described for 
shutdown (e.g., mechanical difficulty), it may be activated again 
without ramp-up if PSOs have maintained constant visual and/or acoustic 
observation and no visual or acoustic detections of marine mammals have 
occurred within the applicable exclusion zone. For any longer shutdown, 
pre-clearance observation and ramp-up are required. For any shutdown at 
night or in periods of poor visibility (e.g., BSS 4 or greater), ramp-
up is required, but if the shutdown period was brief and constant 
observation was maintained, pre-clearance watch of 30 minutes is not 
required; and
     Testing of the acoustic source involving all elements 
requires ramp-up. Testing limited to individual source elements or 
strings does not require ramp-up but does require pre-clearance of 30 
min.

Shutdown

    The shutdown of an airgun array requires the immediate de-
activation of all individual airgun elements of the array. Any PSO on 
duty will have the authority to delay the start of survey operations or 
to call for shutdown of the acoustic source if a marine mammal is 
detected within the applicable exclusion zone. The operator must also 
establish and maintain clear lines of communication directly between 
PSOs on duty and crew controlling the acoustic source to ensure that 
shutdown commands are conveyed swiftly while allowing PSOs to maintain 
watch. When both visual and acoustic PSOs are on duty, all detections 
will be immediately communicated to the remainder of the on-duty PSO 
team for potential verification of visual observations by the acoustic 
PSO or of acoustic detections by visual PSOs. When the airgun array is 
active (i.e., anytime one or more airguns is active, including during 
ramp-up) and (1) a marine mammal appears within or enters the 
applicable exclusion zone and/or (2) a marine mammal (other than 
delphinids, see below) is detected acoustically and localized within 
the applicable exclusion zone, the acoustic source will be shut down. 
When shutdown is called for by a PSO, the acoustic source will be 
immediately deactivated and any dispute resolved only following 
deactivation. Additionally, shutdown will occur whenever PAM alone 
(without visual sighting), confirms presence of marine mammal(s) in the 
EZ. If the acoustic PSO cannot confirm presence within the EZ, visual 
PSOs will be notified but shutdown is not required.
    Following a shutdown, airgun activity will 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, 
beaked whales, killer whales, and Risso's dolphins.
    The shutdown requirement can be waived for small dolphins if an 
individual is visually detected within the exclusion zone. As defined 
here, the small dolphin group is intended to encompass those members of 
the Family Delphinidae most likely to voluntarily approach the source 
vessel for purposes of interacting with the vessel and/or airgun array 
(e.g., bow riding). This exception to the shutdown requirement applies 
solely to specific genera of small dolphins (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., PTS).
    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, 2018). The potential 
for increased shutdowns resulting from such a measure would require the 
Langseth to revisit the missed track line to reacquire data, resulting 
in an overall increase in the total sound energy input to the marine 
environment and an increase in the total duration over which the survey 
is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large delphinids) are no more likely to incur 
auditory injury than are small dolphins, they are much less likely to 
approach vessels. Therefore, retaining a shutdown requirement for large 
delphinids would not have similar impacts in terms of either 
practicability for the applicant or corollary increase in sound energy 
output and time on the water. We do anticipate some benefit for a 
shutdown requirement for large delphinids in that it simplifies 
somewhat the total range of decision-making for PSOs and may preclude 
any potential for physiological effects other than to the auditory 
system as well as some more severe behavioral reactions for any such 
animals in close proximity to the source vessel.
    Visual PSOs shall use best professional judgment in making the 
decision to call for a shutdown if there is uncertainty regarding 
identification (i.e., whether the observed marine mammal(s) belongs to 
one of the delphinid genera for which shutdown is waived or one of the 
species with a larger exclusion zone).
    Upon implementation of shutdown, the source may be reactivated 
after the marine mammal(s) has been observed exiting the applicable 
exclusion zone (i.e., animal is not required to fully exit the buffer 
zone where applicable) or following 15 minutes for small

[[Page 55661]]

odontocetes and pinnipeds, and 30 minutes for mysticetes and all other 
odontocetes, including sperm whales, beaked whales, killer 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; and/or
     A North Pacific right whale.

Vessel Strike Avoidance

    1. Vessel operators and crews must maintain a vigilant watch for 
all protected species and slow down, stop their vessel, or alter 
course, as appropriate and regardless of vessel size, to avoid striking 
any protected species. A visual observer aboard the vessel must monitor 
a vessel strike avoidance zone around the vessel (distances stated 
below). Visual observers monitoring the vessel strike avoidance zone 
may be third-party observers (i.e., PSOs) or crew members, but crew 
members responsible for these duties must be provided sufficient 
training to (1) distinguish protected species from other phenomena and 
(2) broadly to identify a marine mammal as a right whale, other whale 
(defined in this context as sperm whales or baleen whales other than 
right whales), or other marine mammal.
    2. Vessel speeds must also be reduced to 10 knots or less when 
mother/calf pairs, pods, or large assemblages of cetaceans are observed 
near a vessel.
    3. All vessels must maintain a minimum separation distance of 500 m 
from right whales. 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.
    4. All vessels must maintain a minimum separation distance of 100 m 
from sperm whales and all other baleen whales.
    5. All vessels must, to the maximum extent practicable, attempt to 
maintain a minimum separation distance of 50 m from all other protected 
species, with an understanding that at times this may not be possible 
(e.g., for animals that approach the vessel).
    6. When protected species are sighted while a vessel is underway, 
the vessel shall 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 protected species 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. This does not apply to any vessel towing gear or 
any vessel that is navigationally constrained.
    7. 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.
    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 
proposed action area. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) Action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.

Vessel-Based Visual Monitoring

    As described above, PSO observations will take place during daytime 
airgun operations. During seismic operations, at least five visual PSOs 
would be based aboard the Langseth. Two visual PSOs would be on duty at 
all time during daytime hours. Monitoring shall be conducted in 
accordance with the following requirements:
     The operator shall provide PSOs with bigeye binoculars 
(e.g., 25 x 150; 2.7 view angle; individual ocular focus; height 
control) of appropriate quality (i.e., Fujinon or equivalent) solely 
for PSO use. These shall be pedestal-mounted on the deck at the most 
appropriate vantage point that provides for optimal sea surface 
observation, PSO safety, and safe operation of the vessel; and
     The operator will work with the selected third-party 
observer provider to ensure PSOs have all equipment (including backup 
equipment) needed to adequately perform necessary tasks, including 
accurate determination of distance and bearing to observed marine 
mammals. PSOs must have the following requirements and qualifications:
     PSOs shall be independent, dedicated, trained visual and 
acoustic

[[Page 55662]]

PSOs and must be employed by a third-party observer provider;
     PSOs shall have no tasks other than to conduct 
observational effort (visual or acoustic), collect data, and 
communicate with and instruct relevant vessel crew with regard to the 
presence of protected species and mitigation requirements (including 
brief alerts regarding maritime hazards);
     PSOs shall have successfully completed an approved PSO 
training course appropriate for their designated task (visual or 
acoustic). Acoustic PSOs are required to complete specialized training 
for operating PAM systems and are encouraged to have familiarity with 
the vessel with which they will be working;
     PSOs can act as acoustic or visual observers (but not at 
the same time) as long as they demonstrate that their training and 
experience are sufficient to perform the task at hand;
     NMFS must review and approve PSO resumes accompanied by a 
relevant training course information packet that includes the name and 
qualifications (i.e., experience, training completed, or educational 
background) of the instructor(s), the course outline or syllabus, and 
course reference material as well as a document stating successful 
completion of the course;
     NMFS shall have one week to approve PSOs from the time 
that the necessary information is submitted, after which PSOs meeting 
the minimum requirements shall automatically be considered approved;
     PSOs must successfully complete relevant training, 
including completion of all required coursework and passing (80 percent 
or greater) a written and/or oral examination developed for the 
training program;
     PSOs must have successfully attained a bachelor's degree 
from an accredited college or university with a major in one of the 
natural sciences, a minimum of 30 semester hours or equivalent in the 
biological sciences, and at least one undergraduate course in math or 
statistics; and
     The educational requirements may be waived if the PSO has 
acquired the relevant skills through alternate experience. Requests for 
such a waiver shall be submitted to NMFS and must include written 
justification. Requests shall be granted or denied (with justification) 
by NMFS within one week of receipt of submitted information. Alternate 
experience that may be considered includes, but is not limited to (1) 
secondary education and/or experience comparable to PSO duties; (2) 
previous work experience conducting academic, commercial, or 
government-sponsored protected species surveys; or (3) previous work 
experience as a PSO; the PSO should demonstrate good standing and 
consistently good performance of PSO duties.
    For data collection purposes, PSOs shall use standardized data 
collection forms, whether hard copy or electronic. PSOs shall record 
detailed information about any implementation of mitigation 
requirements, including the distance of animals to the acoustic source 
and description of specific actions that ensued, the behavior of the 
animal(s), any observed changes in behavior before and after 
implementation of mitigation, and if shutdown was implemented, the 
length of time before any subsequent ramp-up of the acoustic source. If 
required mitigation was not implemented, PSOs should record a 
description of the circumstances. At a minimum, the following 
information must be recorded:
     Vessel names (source vessel and other vessels associated 
with survey) and call signs;
     PSO names and affiliations;
     Dates of departures and returns to port with port name;
     Date and participants of PSO briefings;
     Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort;
     Vessel location (latitude/longitude) when survey effort 
began and ended and vessel location at beginning and end of visual PSO 
duty shifts;
     Vessel heading and speed at beginning and end of visual 
PSO duty shifts and upon any line change;
     Environmental conditions while on visual survey (at 
beginning and end of PSO shift and whenever conditions changed 
significantly), including BSS and any other relevant weather conditions 
including cloud cover, fog, sun glare, and overall visibility to the 
horizon;
     Factors that may have contributed to impaired observations 
during each PSO shift change or as needed as environmental conditions 
changed (e.g., vessel traffic, equipment malfunctions); and
     Survey activity information, such as acoustic source power 
output while in operation, number and volume of airguns operating in 
the array, tow depth of the array, and any other notes of significance 
(i.e., pre-clearance, ramp-up, shutdown, testing, shooting, ramp-up 
completion, end of operations, streamers, etc.).
    The following information should be recorded upon visual 
observation of any protected species:
     Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
     PSO who sighted the animal;
     Time of sighting;
     Vessel location at time of sighting;
     Water depth;
     Direction of vessel's travel (compass direction);
     Direction of animal's travel relative to the vessel;
     Pace of the animal;
     Estimated distance to the animal and its heading relative 
to vessel at initial sighting;
     Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified) and the composition of the 
group if there is a mix of species;
     Estimated number of animals (high/low/best);
     Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
     Description (as many distinguishing features as possible 
of each individual seen, including length, shape, color, pattern, scars 
or markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
     Detailed behavior observations (e.g., number of blows/
breaths, number of surfaces, breaching, spyhopping, diving, feeding, 
traveling; as explicit and detailed as possible; note any observed 
changes in behavior);
     Animal's closest point of approach 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.

[[Page 55663]]

Reporting

    A report must be submitted to NMFS within 90 days after the end of 
the cruise. The report would describe the operations that were 
conducted and sightings of marine mammals near the operations. The 
report would provide full documentation of methods, results, and 
interpretation pertaining to all monitoring. The 90-day report must 
summarize the dates and locations of seismic operations, all marine 
mammal sightings (dates, times, locations, activities, associated 
seismic survey activities), and all information required to be 
collected (as listed in the preceding section).
    The draft report shall also include geo-referenced time-stamped 
vessel tracklines for all time periods during which airguns were 
operating. Tracklines should include points recording any change in 
airgun status (e.g., when the airguns began operating, when they were 
turned off, or when they changed from full array to single gun or vice 
versa). GIS files shall be provided in ESRI shapefile format and 
include the UTC date and time, latitude in decimal degrees, and 
longitude in decimal degrees. All coordinates shall be referenced to 
the WGS84 geographic coordinate system. In addition to the report, all 
raw observational data shall be made available to NMFS. The report must 
summarize the data collected as described above and in the IHA. A final 
report must be submitted within 30 days following resolution of any 
comments on the draft report.

Reporting Injured or Dead Marine Mammals

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

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

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

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of

[[Page 55664]]

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 1, 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.
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of L-DEO's planned survey, even in the absence of 
mitigation, and none is authorized. Similarly, non-auditory physical 
effects, stranding, and vessel strike are not expected to occur.
    We are authorizing a limited number of instances of Level A 
harassment of seven species (low- and high-frequency cetacean hearing 
groups only) and Level B harassment only of the remaining marine mammal 
species. However, we believe that any PTS incurred in marine mammals as 
a result of the planned activity would be in the form of only a small 
degree of PTS, not total deafness, because of the constant movement of 
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. Since the duration of 
exposure to loud sounds will be relatively short it would be unlikely 
to affect the fitness of any individuals. Also, as described above, we 
expect that marine mammals would likely 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).
    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 (16 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 
critical habitat areas for the Steller sea lion and to a feeding BIA 
for humpback whales. However, only a portion of seismic survey days 
would actually occur in or near these areas. As described previously, 
L-DEO's planned tracklines do not extend within 3 nmi of any island, 
and L-DEO has agreed to reduce the active array by half of the 
elements, also reducing the total array volume by half, over the 10 
percent of planned tracklines that are closest to shore. Finally, L-DEO 
has agreed to maintain a standoff distance around specific Steller sea 
lion haul-outs and rookeries such that the modeled Level B harassment 
zone would not overlap a 3,000-ft (0.9-km) buffer around those areas. 
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.
    Yazvenko et al. (2007b) reported no apparent changes in the 
frequency of feeding activity in Western gray whales exposed to airgun 
sounds in their feeding grounds near Sakhalin Island. Goldbogen et al. 
(2013) found blue whales feeding on highly concentrated prey in shallow 
depths (such as the conditions expected within humpback feeding BIAs) 
were less likely to respond and cease foraging than whales feeding on 
deep, dispersed prey when exposed to simulated sonar sources, 
suggesting that the benefits of feeding for humpbacks foraging on high-
density prey may outweigh perceived harm from the acoustic stimulus, 
such as the seismic survey (Southall et al., 2016). Additionally, L-DEO 
will shut down the airgun array upon observation of an aggregation of 
six or more large whales, which would reduce impacts to cooperatively 
foraging animals. For all habitats, no physical impacts to 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 important habitat areas, 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 these areas.

Negligible Impact Conclusions

    The survey will be of short duration (16 days of seismic 
operations), and the acoustic ``footprint'' of the survey will be small 
relative to the ranges of the marine mammals that would 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 survey vessel would pass Steller sea lion 
critical habitat only briefly, and would operate at half volume during 
the ten percent of tracklines closest to the islands.
    The required 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

[[Page 55665]]

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 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).
    NMFS concludes that exposures to marine mammal species and stocks 
due to L-DEO's 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 takes 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 activity is temporary and of relatively short duration 
(16 days);
     The anticipated impacts of the activity on marine mammals 
would primarily be temporary behavioral changes due to avoidance of the 
area around the survey vessel;
     The number of instances of potential PTS that may occur 
are expected to be very small in number. Instances of potential PTS 
that are incurred in marine mammals are expected to be of a low level, 
due to constant movement of the vessel and of the marine mammals in the 
area, and the nature of the survey design (not concentrated in areas of 
high marine mammal concentration);
     The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the 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 measures, including visual and acoustic 
monitoring, shutdowns, and use of the reduced array in certain areas 
adjacent to Steller sea lion critical habitat are expected to minimize 
potential impacts to marine mammals (both amount and severity).
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the mitigation and monitoring 
measures, NMFS finds that the total marine mammal take from the 
proposed activity will have a negligible impact on all affected marine 
mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    There are several stocks for which the estimated instances of take 
appear high when compared to the stock abundance (Table 6), or for 
which there is no currently accepted stock abundance estimate. These 
include the humpback whale, fin whale, minke whale, sperm whale, four 
species of beaked whale, and the offshore stock of killer whales. 
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 those referenced above and 
discussed 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).
    Existing stock abundance estimates for humpback whales, based on 
2006 surveys, are 10,103 animals for the CNP stock and 1,107 animals 
for the WNP stock. If all takes are assumed to accrue to the WNP stock, 
the resulting percentage would not be a small number. Here, we refer to 
additional pieces of information that demonstrate the authorized taking 
to be of no greater than small numbers. First, Wade (2017) provides a 
more recent estimate of 14,693 whales for the summer (feeding area) 
abundance in the Aleutian Islands and Bering Sea, which includes the 
survey area. The total estimated take of humpback whale (1,948 take 
incidents) would be 13.3 percent of this estimated summer abundance, 
i.e., less than NMFS' small numbers threshold of one-third of the best 
available abundance estimate. Second, we expect that only 2.1 percent 
of whales encountered in this area would be from the WNP DPS. If we 
consider the WNP DPS to be a reasonable approximation of the historic 
WNP stock designation, then approximately 41 takes should be expected 
to accrue to the stock (or approximately 3.7 percent of the 2006 
abundance estimate for the WNP stock). This information supports a 
determination that the take authorization for humpback whales would be 
of no greater than small numbers, for any stock.
    The stock abundance estimates for the fin, minke, beaked, and sperm 
whale stocks that occur in the survey area are unknown, according to 
the latest SARs. Therefore, we reviewed other scientific information in 
making our small numbers determinations for these species. As noted 
previously, partial abundance estimates of 1,233 and 2,020 minke whales 
are available for shelf and nearshore waters between the Kenai 
Peninsula and Amchitka Pass and for the eastern Bering Sea shelf, 
respectively. For the minke whale, these partial abundance estimates 
alone are sufficient to demonstrate that the take number of 29 is of 
small numbers. The same surveys produced partial abundance estimates of 
1,652 and 1,061 fin whales, for the same areas, respectively. For the 
fin whale, we must turn to the only available region-wide abundance 
estimate. Ohsumi and Wada (1974) provided an estimated North Pacific 
abundance of 13,620-18,680 whales. Using the lower bound produces a 
proportion of 12.9 percent.
    As noted previously, Kato and Miyashita (1998) produced an 
abundance estimate of 102,112 sperm whales in the western North 
Pacific. However, this estimate is believed to be positively biased. We 
therefore refer to Barlow and Taylor (2005)'s estimate of 26,300 sperm 
whales in the northeast temperate Pacific to demonstrate that the take 
number of 43 is a small number. There is no abundance information 
available for any Alaskan stock of beaked whale. However, the take 
numbers are sufficiently small (ranging from 9-106) that we can safely

[[Page 55666]]

assume that they are small relative to any reasonable assumption of 
likely population abundance for these stocks. For reference, current 
abundance estimates for other Pacific beaked whale stocks include 3,044 
Mesoplodont beaked whales (California/Oregon/Washington stock), 3,274 
Cuvier's beaked whales (CA/OR/WA stock), 2,105 Blainville's beaked 
whales (Hawaii Pelagic stock), 7,619 Longman's beaked whales (Hawaii 
stock), and 723 Cuvier's beaked whales (HI Pelagic stock).
    For the offshore stock of killer whale, it would be unreasonable to 
assume that all takes would accrue to this stock (which would result in 
the take of 47 percent of the population). During surveys from the 
Kenai Fjords to Amchitka Pass in the central Aleutian Islands, 59 
groups totaling 1,038 individual killer whales were seen, including 39 
(66 percent) residents, 14 (24 percent) transients, 2 (3 percent) 
offshore, and 4 (7 percent) unknown (Wade et al., 2003). Based on this 
information, we assume it relatively unlikely that encountered killer 
whales will be of the offshore stock, and that take of offshore killer 
whales, if any, would be of small numbers.
    Based on the analysis contained herein of the activity (including 
the 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 is some sealing by indigenous groups in the survey area in 
the Aleutian Islands. However, given the temporary nature of the 
planned activities and the fact that all operations would occur more 
than 3 nmi from shore, the activity would not be expected to have any 
impact on the availability of the species or stocks for subsistence 
users. L-DEO conducted outreach to the Aleut Marine Mammal Commission 
and to the Alaska Sea Otter and Steller Sea Lion Commission to notify 
subsistence hunters of the planned survey, to identify the measures 
that would be taken to minimize any effects on the availability of 
marine mammals for subsistence uses, and to provide an opportunity for 
comment on these measures. L-DEO received confirmation from the Aleut 
Marine Mammal Commissioners that there were no concerns regarding the 
potential effects of the planned survey on the potential availability 
of marine mammals for subsistence uses. NMFS is unaware of any other 
subsistence uses of the affected marine mammal stocks or species that 
could be implicated by this action. Therefore, NMFS has determined that 
the total taking of affected species or stocks would not have an 
unmitigable adverse impact on the availability of such species or 
stocks for taking for subsistence purposes.

National Environmental Policy Act

    In compliance with the National Environmental Policy Act of 1969 
(42 U.S.C. 4321 et seq.), as implemented by the regulations published 
by the Council on Environmental Quality (40 CFR parts 1500-1508), the 
National Science Foundation prepared an Environmental Analysis (EA) to 
consider the direct, indirect, and cumulative effects to the human 
environment from this marine geophysical survey in the Aleutian 
Islands. NSF's EA was made available to the public for review and 
comment in relation to its suitability for adoption by NMFS in order to 
assess the impacts to the human environment of issuance of an IHA to L-
DEO. In compliance with NEPA and the CEQ regulations, as well as NOAA 
Administrative Order 216-6, NMFS has reviewed the NSF's EA, determined 
it to be sufficient, and adopted that EA and signed a Finding of No 
Significant Impact (FONSI). NSF's EA is available at www.nsf.gov/geo/oce/envcomp/, and NMFS' FONSI is available at www.fisheries.noaa.gov/action/incidental-take-authorization-lamont-doherty-earth-observatory-marine-geophysical-survey-2.

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 (OPR) 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 the sei whale, fin whale, blue 
whale, sperm whale, humpback whale (Western North Pacific DPS and 
Mexico DPS), western North Pacific gray whale, and western DPS of 
Steller sea lion.

Authorization

    As a result of these determinations, NMFS has issued an IHA to L-
DEO for conducting a marine geophysical survey in the Aleutian Islands 
beginning in September 2020, provided the previously mentioned 
mitigation, monitoring, and reporting requirements are incorporated.

    Dated: September 2, 2020.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2020-19815 Filed 9-8-20; 8:45 am]
BILLING CODE 3510-22-P