Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Marine Geophysical Survey in the Aleutian Islands, 45389-45411 [2020-16322]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 85, Number 145 (Tuesday, July 28, 2020)]
[Notices]
[Pages 45389-45411]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-16322]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XA248]


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

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

DATES: Comments and information must be received no later than August 
27, 2020.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Physical comments should be sent to 
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments 
should be sent to [email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments received electronically, including 
all attachments, must not exceed a 25-megabyte file size. All comments 
received are a part of the public record and will generally be posted 
online at www.fisheries.noaa.gov/permit/

[[Page 45390]]

incidental-take-authorizations-under-marine-mammal-protection-act 
without change. All personal identifying information (e.g., name, 
address) voluntarily submitted by the commenter may be publicly 
accessible. Do not submit confidential business information or 
otherwise sensitive or protected information.

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

SUPPLEMENTARY INFORMATION:

Background

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

National Environmental Policy Act

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

Summary of Request

    On 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. L-DEO's request is for take of 23 species of marine 
mammals by Level B harassment. In addition, NMFS proposes to authorize 
take by Level A harassment for seven of these species.

Description of Proposed Activity

Overview

    Researchers from L-DEO and Woods Hole Oceanographic Institution 
(WHOI), with funding from NSF, propose 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 proposed two-dimensional (2-D) seismic survey would 
occur within the Exclusive Economic Zone (EEZ) of the United States. 
The survey would use a 36-airgun towed array with a total discharge 
volume of ~6,600 cubic inches (in\3\) as an acoustic source, acquiring 
return signals using both a towed streamer as well as ocean bottom 
seismometers (OBSs).
    The proposed study would 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 proposed 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 would likely leave out of and return to port in 
Dutch Harbor, Alaska, during September-October 2020.

Specific Geographic Region

    The proposed survey would 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 in L-DEO's application. 
Tracklines in the vicinity of specific Steller sea lion haul-outs and 
rookeries have subsequently been modified in order to ensure that the 
area assumed to be ensonified above the Level B harassment threshold 
(see ``Estimated Take'') does not extend beyond a 3,000 foot (0.9 km) 
buffer around those areas. Some deviation in actual track lines, 
including the order of survey operations, could be necessary for 
reasons such as science drivers, poor data quality, inclement weather, 
or mechanical issues with the research vessel and/or equipment. The 
survey is proposed to occur within the 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 would 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 proposed surveys would be similar 
to those used during previous seismic surveys by L-DEO and would use 
conventional seismic methodology. The surveys would involve one source 
vessel, R/V Langseth, which is owned by NSF and operated on its behalf 
by L-

[[Page 45391]]

DEO. R/V Langseth would deploy an array of 36 airguns as an energy 
source with a total volume of 6,600 in\3\. The array consists of 36 
elements, including 20 Bolt 1500LL airguns with volumes of 180 to 360 
in\3\ and 16 Bolt 1900LLX airguns with volumes of 40 to 120 in\3\. The 
airgun array configuration is illustrated in Figure 2-11 of NSF and 
USGS's Programmatic Environmental Impact Statement (PEIS; NSF-USGS, 
2011). (The 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 would be 
approximately 4.5 knots (~8.3 km/hour) during the survey and the airgun 
array would be towed at a depth of 9 m. The receiving system would 
consist 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 would transfer the data to the on-board processing 
system, and the OBSs would receive and store the returning acoustic 
signals internally for later analysis.
    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). The representative tracklines shown 
in Figure 1 of L-DEO's application have a total length of 2,010 km. The 
strike- and dip-line transects would first be acquired using OBSs, 
which would be deployed along one line at a time, the line would be 
surveyed, and the OBSs would then be recovered, before moving onto the 
next line. After all refraction data is acquired, the strike and dip 
lines would be acquired a second time using MCS. The MCS transect lines 
and Amlia Fracture Zone transect lines would 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-kms to account for 
this potential.
    For the majority of the survey (90 percent), R/V Langseth would 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 of L-DEO's application) closest to islands, 
only half the array (18 airguns) would be operated, with a total volume 
of approximately 3,300 in\3\. The airguns would fire at a shot interval 
of 22 s during MCS shooting with the hydrophone streamer and at a 120-s 
interval during refraction surveying to OBSs.
    The seismometers would consist of short-period multi-component OBSs 
from Scripps Institution of Oceanography (SIO). Fifty OBSs would 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 
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-kg 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) would 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 brief 
ping exposures, if any exposure were to occur. Proposed mitigation, 
monitoring, and reporting measures are described in detail later in 
this document (please see Proposed Mitigation and Proposed Monitoring 
and Reporting).

Description of Marine Mammals in the Area of Specified Activities

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

[[Page 45392]]



                                               Table 1--Marine Mammals That Could Occur in the Survey Area
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                                                                                                             Stock abundance (CV,
             Common name                  Scientific name               Stock           ESA/ MMPA status;      Nmin, most recent       PBR     Annual M/
                                                                                       strategic (Y/N) \1\   abundance survey) \2\               SI \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) *.                                     2006).
                                                               Western North Pacific   E/D; Y               1,107 (0.3; 865; 2006)          3        2.6
                                                                *.
    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;      \12\ 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
    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
                                                               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).
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                                                         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 angustirostris  California Breeding...  -; N                 179,000 (n/a; 81,368;       4,882        8.8
                                                                                                             2010).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Stocks marked with an asterisk are addressed in further detail in text below.
\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 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 draft 2019 SARs.
\4\ Transient and resident killer whales are considered unnamed subspecies (Committee on Taxonomy, 2019).
\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.


[[Page 45393]]

    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.
    Although no comprehensive abundance estimate is available for the 
Alaska stock of minke whales, recent surveys provide estimates for 
portions of the stock's range. A 2010 survey conducted on the eastern 
Bering Sea shelf produced a provisional abundance estimate of 2,020 (CV 
= 0.73) whales (Friday et al., 2013). This estimate is considered 
provisional because it has not been corrected for animals missed on the 
trackline, animals submerged when the ship passed, or responsive 
movement. Additionally, line-transect surveys were conducted in shelf 
and nearshore waters (within 30-45 nautical miles of land) in 2001-2003 
between the Kenai Peninsula (150[deg] W) and Amchitka Pass (178[deg] 
W). Minke whale abundance was estimated to be 1,233 (CV = 0.34) for 
this area (also not been corrected for animals missed on the trackline) 
(Zerbini et al., 2006). The majority of the sightings were in the 
Aleutian Islands, rather than in the Gulf of Alaska, and in water 
shallower than 200 m. These estimates cannot be used as an estimate of 
the entire Alaska stock of minke whales because only a portion of the 
stock's range was surveyed. Similarly, although a comprehensive 
abundance estimate is not available for the northeast Pacific stock of 
fin whales, provisional estimates representing portions of the range 
are available. The same 2010 survey of the eastern Bering sea shelf 
provided an estimate of 1,061 (CV = 0.38) fin whales (Friday et al., 
2013). The estimate is not corrected for missed animals, but is 
expected to be robust as previous studies have shown that only small 
correction factors are needed for fin whales (Barlow, 1995). Zerbini et 
al. (2006) produced an estimate of 1,652 (95% CI: 1,142-2,389) fin 
whales for the area described above.
    Current and historical estimates of the abundance of sperm whales 
in the North Pacific are considered unreliable, and caution should be 
exercised in interpreting published estimates (Muto et al., 2017). 
However, Kato and Miyashita (1998) produced an abundance estimate of 
102,112 (CV = 0.155) sperm whales in the western North Pacific 
(believed to be positively biased). The number of sperm whales 
occurring within Alaska waters is unknown.
    Northern right whale dolphins and Risso's dolphins do not typically 
occur in waters surrounding the Aleutian Islands, though there have 
been rare sightings and acoustic detections in the region. NMFS 
considers these species extralimital to the survey area. However, L-DEO 
has requested the authorization of incidental take for these species, 
and we are acting on that request.
    Ribbon seals and spotted seals are considered rare in the survey 
area. From late March to early May, ribbon seals inhabit the Bering Sea 
ice front. They are most abundant in the northern part of the ice front 
in the central and western parts of the Bering Sea. As the ice recedes 
in May to mid-July, the seals move farther north in the Bering Sea, 
where they haul out on the receding ice edge and remnant ice. As the 
ice melts, seals become more concentrated, with at least part of the 
Bering Sea population moving to the Bering Strait and the southern part 
of the Chukchi Sea. The distribution of spotted seals is seasonally 
related to specific life-history events that can be broadly divided 
into two periods: Late-fall through spring, when whelping, nursing, 
breeding, and molting occur in association with the presence of sea ice 
on which the seals haul out, and summer through fall when seasonal sea 
ice has melted and most spotted seals use land for hauling out. 
Satellite-tagging studies showed that seals tagged in the northeastern 
Chukchi Sea moved south in October and passed through the Bering Strait 
in November. Seals overwintered in the Bering Sea along the ice edge 
and made east-west movements along the edge. In summer and fall, 
spotted seals use coastal haul-out sites regularly and may be found as 
far north as 69-72[deg] N in the Chukchi and Beaufort seas. To the 
south, along the west coast of Alaska, spotted seals are known to occur 
around the Pribilof Islands, Bristol Bay, and the eastern Aleutian 
Islands. Although we do not expect these species of seals to be 
encountered, L-DEO has requested has requested the authorization of 
incidental take for these species, and we are acting on that request.
    In addition, the northern (or eastern) sea otter (Enhydra lutris 
kenyoni) may be found in coastal waters of the survey area. However, 
sea otters are managed by the U.S. Fish and Wildlife Service and are 
not considered further in this document.

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[deg] 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 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 (GOA). 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

[[Page 45394]]

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 GOA. 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 GOA, 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-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.

[[Page 45395]]



                  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) (underwater).........  50 Hz to 86 kHz.
(true seals)...............................
Otariid pinnipeds (OW) (underwater)........  60 Hz to 39 kHz.
(sea lions and fur seals)..................
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Twenty-three marine mammal species (17 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), eight 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; 84 FR 14200; 85 FR 19580). 
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 preliminarily 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 ``Proposed Mitigation'' section, to 
draw conclusions regarding the likely impacts of these activities on 
the reproductive success or survivorship of individuals and how those 
impacts on individuals are likely to impact marine mammal species or 
stocks.

Description of Active Acoustic Sound Sources

    This section contains a brief technical background on sound, 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. 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).
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz or cycles per second. Wavelength is the distance 
between two peaks or corresponding points of a sound wave (length of 
one cycle). Higher frequency sounds have shorter wavelengths than lower 
frequency sounds, and typically attenuate (decrease) more rapidly, 
except in certain cases in shallower water. Amplitude is the height of 
the sound pressure wave or the ``loudness'' of a sound and is typically 
described using the relative unit of the decibel. A sound pressure 
level (SPL) in dB is described as the ratio between a measured pressure 
and a reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)), and is a logarithmic unit that accounts for large variations 
in amplitude. Therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. The source level (SL) represents the 
SPL referenced at a distance of 1 m from the source (referenced to 1 
[mu]Pa), while the received level is the SPL at the listener's position 
(referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they may be accounted for in the summation of 
pressure levels (Hastings and Popper, 2005). This measurement is often 
used in the context of discussing behavioral effects, in part because 
behavioral effects, which often result from auditory cues, may be 
better expressed through averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa\2\-s) 
represents the total energy in a stated frequency

[[Page 45396]]

band over a stated time interval or event and considers both intensity 
and duration of exposure. The per-pulse SEL is calculated over the time 
window containing the entire pulse (i.e., 100 percent of the acoustic 
energy). SEL is a cumulative metric; it can be accumulated over a 
single pulse, or calculated over periods containing multiple pulses. 
Cumulative SEL represents the total energy accumulated by a receiver 
over a defined time window or during an event. Peak sound pressure 
(also referred to as zero-to-peak sound pressure or 0-pk) is the 
maximum instantaneous sound pressure measurable in the water at a 
specified distance from the source and is represented in the same units 
as the rms sound pressure.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or may radiate in all directions 
(omnidirectional sources), as is the case for sound produced by the 
pile driving activity considered here. The compressions and 
decompressions associated with sound waves are detected as changes in 
pressure by aquatic life and man-made sound receptors such as 
hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound, which is 
defined as environmental background sound levels lacking a single 
source or point (Richardson et al., 1995). The sound level of a region 
is defined by the total acoustical energy being generated by known and 
unknown sources. These sources may include physical (e.g., wind and 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
(e.g., vessels, dredging, construction) sound. A number of sources 
contribute to ambient sound, including wind and waves, which are a main 
source of naturally occurring ambient sound for frequencies between 200 
Hz and 50 kHz (Mitson, 1995). In general, ambient sound levels tend to 
increase with increasing wind speed and wave height. Precipitation can 
become an important component of total sound at frequencies above 500 
Hz, and possibly down to 100 Hz during quiet times. Marine mammals can 
contribute significantly to ambient sound levels, as can some fish and 
snapping shrimp. The frequency band for biological contributions is 
from approximately 12 Hz to over 100 kHz. Sources of ambient sound 
related to human activity include transportation (surface vessels), 
dredging and construction, oil and gas drilling and production, 
geophysical surveys, sonar, and explosions. Vessel noise typically 
dominates the total ambient sound for frequencies between 20 and 300 
Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz 
and, if higher frequency sound levels are created, they attenuate 
rapidly.
    The sum of the various natural and anthropogenic sound sources that 
comprise ambient sound at any given location and time depends not only 
on the source levels (as determined by current weather conditions and 
levels of biological and human activity) but also on the ability of 
sound to propagate through the environment. In turn, sound propagation 
is dependent on the spatially and temporally varying properties of the 
water column and sea floor, and is frequency-dependent. As a result of 
the dependence on a large number of varying factors, ambient sound 
levels can be expected to vary widely over both coarse and fine spatial 
and temporal scales. Sound levels at a given frequency and location can 
vary by 10-20 dB from day to day (Richardson et al., 1995). The result 
is that, depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals. Details of source types are described in the following text.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al. (2007) for an in-depth discussion of these concepts. 
The distinction between these two sound types is not always obvious, as 
certain signals share properties of both pulsed and non-pulsed sounds. 
A signal near a source could be categorized as a pulse, but due to 
propagation effects as it moves farther from the source, the signal 
duration becomes longer (e.g., Greene and Richardson, 1988).
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or intermittent (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems. The 
duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.
    Airgun arrays produce pulsed signals with energy in a frequency 
range from about 10-2,000 Hz, with most energy radiated at frequencies 
below 200 Hz. The amplitude of the acoustic wave emitted from the 
source is equal in all directions (i.e., omnidirectional), but airgun 
arrays do possess some directionality due to different phase delays 
between guns in different directions. Airgun arrays are typically tuned 
to maximize functionality for data acquisition purposes, meaning that 
sound transmitted in horizontal directions and at higher frequencies is 
minimized to the extent possible.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers'' and the negligible impact 
determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).

[[Page 45397]]

    Authorized takes would primarily be by Level B harassment, as use 
of seismic airguns has the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory injury (Level A harassment) for mysticetes and 
high frequency cetaceans (i.e., porpoises). The proposed mitigation and 
monitoring measures are expected to minimize the severity of such 
taking to the extent practicable.
    As described previously, no serious injury or mortality is 
anticipated or proposed to be authorized for this activity. Below we 
describe how the take is estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and, (4) 
and the number of days of activities. We note that while these basic 
factors can contribute to a basic calculation to provide an initial 
prediction of takes, additional information that can qualitatively 
inform take estimates is also sometimes available (e.g., previous 
monitoring results or average group size). Below, we describe the 
factors considered here in more detail and present the proposed take 
estimate.

Acoustic Thresholds

    NMFS uses acoustic thresholds that identify the received level of 
underwater sound above which exposed marine mammals would be reasonably 
expected to be behaviorally harassed (equated to Level B harassment) or 
to incur PTS of some degree (equated to Level A harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). NMFS uses a generalized acoustic threshold based 
on received level to estimate the onset of behavioral harassment. NMFS 
predicts that marine mammals may be behaviorally harassed (i.e., Level 
B harassment) when exposed to underwater anthropogenic noise above 
received levels 160 dB re 1 [mu]Pa (rms) for the impulsive sources 
(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 proposed seismic survey includes 
the use of impulsive (seismic airguns) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 3--Thresholds Identifying the Onset of Permanent Threshold Shift
----------------------------------------------------------------------------------------------------------------
                                                     PTS onset acoustic thresholds * (received level)
             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 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[mu]Pa\2\s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and acoustic 
propagation modeling.
    L-DEO's modeling methodologies are described in greater detail in 
Appendix A of L-DEO's IHA application. The proposed 2D survey would 
acquire data using the 36-airgun array with a total discharge volume of 
6,600 in\3\ at a maximum tow depth of 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

[[Page 45398]]

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. (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 (m)    harassment zone
                                                                                                      (m)
----------------------------------------------------------------------------------------------------------------
36 airgun array; 6,600 in\3\..............................               9              >1000          \1\ 5,629
                                                                                     100-1000          \3\ 8,233
                                                                                         <100         \3\ 11,000
18 airgun array; 3,300 in\3\..............................               9              >1000          \1\ 3,562
                                                                                     100-1000          \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 SELcum and peak sound pressure metrics (NMFS 
2018). As dual metrics, NMFS considers onset of PTS (Level A 
harassment) to have occurred when either one of the two metrics is 
exceeded (i.e., metric resulting in the largest isopleth). The 
SELcum metric considers both level and duration of exposure, 
as well as auditory weighting functions by marine mammal hearing group. 
In recognition of the fact that the requirement to calculate Level A 
harassment ensonified areas could be more technically challenging to 
predict due to the duration component and the use of weighting 
functions in the new SELcum thresholds, NMFS developed an 
optional User Spreadsheet that includes tools to help predict a simple 
isopleth that can be used in conjunction with marine mammal density or 
occurrence to facilitate the estimation of take numbers.
    The values for SELcum and peak SPL for the Langseth 
airgun 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) was used to make adjustments (dB) to the unweighted spectrum 
levels, by frequency, according to the weighting functions for each 
relevant marine mammal hearing group. These adjusted/weighted spectrum 
levels were then converted to pressures ([mu]Pa) in order to integrate 
them over the entire broadband spectrum, resulting in broadband 
weighted source levels by

[[Page 45399]]

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 Spreadsheets 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 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 the proposed seismic survey, the User Spreadsheet predicts the 
closest distance at which a stationary animal would not incur PTS if 
the sound source traveled by the animal in a straight line at a 
constant speed.
    Auditory injury is unlikely to occur for mid-frequency cetaceans, 
otariid pinnipeds, and phocid pinnipeds given very small modeled zones 
of injury for those species (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 230 dB peak isopleth distances would in 
all cases be expected to be within the near-field of the array where 
the definition of source level breaks down. Therefore, actual locations 
within this distance of the array center where the sound level exceeds 
230 dB peak SPL would not necessarily exist. In general, Caldwell and 
Dragoset (2000) suggest that the near-field for airgun arrays is 
considered to extend out to approximately 250 m.
    In order to provide quantitative support for this theoretical 
argument, we calculated expected maximum distances at which the near-
field would transition to the far-field (Table 5). For a specific array 
one can estimate the distance at which the near-field transitions to 
the far-field by:
[GRAPHIC] [TIFF OMITTED] TN28JY20.001

with the condition that D >> l, and where D is the distance, L is the 
longest dimension of the array, and l is the wavelength of the signal 
(Lurton, 2002). Given that l can be defined by:
[GRAPHIC] [TIFF OMITTED] TN28JY20.002

where f is the frequency of the sound signal and v is the speed of the 
sound in the medium of interest, one can rewrite the equation for D as:
[GRAPHIC] [TIFF OMITTED] TN28JY20.003

and calculate D directly given a particular frequency and known speed 
of sound (here assumed to be 1,500 meters per second in water, although 
this varies with environmental conditions).
    To determine the closest distance to the arrays at which the source 
level predictions in Table 5 are valid (i.e., maximum extent of the 
near-field), we calculated D based on an assumed frequency of 1 kHz. A 
frequency of 1 kHz is commonly used in near-field/far-field 
calculations for airgun arrays (Zykov and Carr, 2014; MacGillivray, 
2006; NSF and USGS, 2011), and based on representative airgun spectrum 
data and field measurements of an airgun array used on the Langseth, 
nearly all (greater than 95 percent) of the energy from airgun arrays 
is below 1 kHz (Tolstoy et al., 2009). Thus, using 1 kHz as the upper 
cut-off for calculating the maximum extent of the near-field should 
reasonably represent the near-field extent in field conditions.
    If the largest distance to the peak sound pressure level threshold 
was equal to or less than the longest dimension of the array (i.e., 
under the array), or within the near-field, then received levels that 
meet or exceed the threshold in most cases are not expected to occur. 
This is because within the near-field and within the dimensions of the 
array, the source levels specified in Appendix A of L-DEO's application 
are

[[Page 45400]]

overestimated and not applicable. In fact, until one reaches a distance 
of approximately three or four times the near-field distance the 
average intensity of sound at any given distance from the array is 
still less than that based on calculations that assume a directional 
point source (Lurton, 2002). The 6,600-in\3\ airgun array used during 
90 percent of the proposed survey has an approximate diagonal of 28.8 
m, resulting in a near-field distance of 138.7 m at 1 kHz (NSF and 
USGS, 2011). Field measurements of this array indicate that the source 
behaves like multiple discrete sources, rather than a directional point 
source, beginning at approximately 400 m (deep site) to 1 km (shallow 
site) from the center of the array (Tolstoy et al., 2009), distances 
that are actually greater than four times the calculated 140-m near-
field distance. Within these distances, the recorded received levels 
were always lower than would be predicted based on calculations that 
assume a directional point source, and increasingly so as one moves 
closer towards the array (Tolstoy et al., 2009). Given this, relying on 
the calculated distance (138.7 m) as the distance at which we expect to 
be in the near-field is a conservative approach since even beyond this 
distance the acoustic modeling still overestimates the actual received 
level. Within the near-field, in order to explicitly evaluate the 
likelihood of exceeding any particular acoustic threshold, one would 
need to consider the exact position of the animal, its relationship to 
individual array elements, and how the individual acoustic sources 
propagate and their acoustic fields interact. Given that within the 
near-field and dimensions of the array source levels would be below 
those assumed here, we believe exceedance of the peak pressure 
threshold would only be possible under highly unlikely circumstances.
    In consideration of the received sound levels in the near-field as 
described above, we expect the potential for Level A harassment of mid-
frequency cetaceans, otariid pinnipeds, and phocid pinnipeds to be de 
minimis, even before the likely moderating effects of aversion and/or 
other compensatory behaviors (e.g., Nachtigall et al., 2018) are 
considered. We do not believe that Level A harassment is a likely 
outcome for any mid-frequency cetacean, otariid pinniped, or phocid 
pinniped and do not propose to authorize any Level A harassment for 
these species.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, and group dynamics of marine mammals that will inform the take 
calculations. For additional detail, please see Appendix B of L-DEO's 
application.
    Habitat-based stratified marine mammal densities developed by the 
U.S. Navy for assessing potential impacts of training activities in the 
Gulf of Alaska (GOA) (DoN, 2014; Rone et al., 2014) were used by L-DEO 
for estimating potential marine mammal exposures. The Navy's Marine 
Species Density Database (DoN, 2014) is currently the most 
comprehensive compendium for density data available for the GOA; 
density estimates specific to the survey location in the Aleutian 
Islands are not available. Density values are provided in Table B-1 of 
L-DEO's application.
    The Navy conducted two comprehensive marine mammal surveys in their 
Temporary Marine Activities Area (TMAA) in the GOA prior to 2014. The 
first survey was conducted in April 2009 and the second was from June 
to July 2013. Both surveys used systematic line-transect survey 
protocols including visual and acoustic detection methods (Rone et al., 
2010, 2014). The data were collected in four strata that were designed 
to encompass the four distinct habitats within the TMAA and greater 
GOA. Rone et al. (2014) provided stratified line-transect density 
estimates used in this analysis for fin, humpback, blue, sperm, and 
killer whales, as well as northern fur seals. Data from a subsequent 
survey in 2015 were used to calculate alternative density estimates for 
several species (Rone et al., 2017). However, the reported densities 
for blue, fin and humpback whales were not prorated for unidentified 
large whale sightings so the densities from Rone et al. (2014) were 
maintained.
    Rone et al. (2014) defined four strata: Inshore: All waters <1,000 
m deep; Slope: From 1,000 m water depth to the Aleutian trench/
subduction zone; Offshore: Waters offshore of the Aleutian trench/
subduction zone; Seamount: Waters within defined seamount areas. 
Densities corresponding to these strata were based on data from several 
different sources, including Navy funded line-transect surveys in the 
GOA as described above. Compared to the GOA study area (Rone et al., 
2014), the proposed survey area does not have a consistent gradual 
decrease in water depth (``slope'' habitat) from the 1,000 m isobath to 
the Aleutian Trench, south of the Aleutian Islands. Instead, water 
depths initially decrease rapidly beyond the 1,000-m isobath to ~4,000 
m, then rise again on Hawley Ridge before dropping in the Aleutian 
Trench. Additionally, waters north of the Aleutian Islands and beyond 
1,000 m drop rapidly to ~3,000 m and remain at those depths to the 
northern extent of the survey lines. For those reasons, and because the 
Rone et al. (2014) inshore densities were for all waters <1,000 m, the 
marine mammal densities for the Inshore region were used for both 
shallow (<100 m) and intermediate (100-1,000 m) water depths, while 
offshore densities were used for all deepwater areas >1,000 m.
    There were insufficient sightings data from the 2009, 2013 and 2015 
line-transect surveys to calculate reliable density estimates for other 
marine mammal species in the GOA. DoN (2014) derived gray whale 
densities in two zones, nearshore (0-2.25 nmi from shore) and offshore 
(from 2.25-20 nmi from shore). L-DEO used the nearshore density to 
represent shallow water (<100 m deep), and the offshore density for 
intermediate and deep water. Harbor porpoise densities in DoN (2014) 
were derived from Hobbs and Waite (2010) which included additional 
shallow water depth strata. The density estimate from the 100-200 m 
depth strata was used for both shallow and intermediate-depth water in 
this analysis. Similarly, harbor seals typically remain close to shore 
so minimal estimates for deep water and a one thousand fold increase of 
the minimal density was used for shallow and intermediate waters (DoN, 
2014). The density estimates for Dall's porpoise in Rone et al. (2017) 
were somewhat larger than those in Rone et al. (2014), so the larger 
densities are used here.
    Densities for minke whale, Pacific white-sided dolphin, and 
Cuvier's and Baird's beaked whales were based on Waite (2003 in DoN, 
2009). Although sei whale sightings and Stejneger's beaked whale 
acoustic detections were recorded during the Navy-funded GOA surveys, 
data were insufficient to calculate densities for these species, so 
predictions from a global model of marine mammal densities were used 
(Kaschner et al., 2012 in DoN, 2014). Steller sea lion and northern 
elephant seal densities were calculated using shore-based population 
estimates divided by the area of the GOA Large Marine Ecosystem (DoN, 
2014). For the Steller sea lion in particular, we invite comment on the 
suitability of these data and regarding the availability of alternative 
density information, if any. The North Pacific right whale and Risso's 
dolphin are only rarely observed in or near the survey area, so minimal 
densities were used to represent their potential presence (DoN, 2014). 
No regional density information is available

[[Page 45401]]

for the northern right whale dolphin, spotted seal, or ribbon seal.
    All densities were corrected for perception bias [f(0)] but only 
harbor porpoise densities were corrected for availability bias [g(0)], 
as described by the respective authors. There is some uncertainty 
related to the estimated density data and the assumptions used in their 
calculations, as with all density data estimates. However, the approach 
used here is based on the best available data that are stratified by 
the water depth (habitat) zones present within the survey area.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. In order to estimate 
the number of marine mammals predicted to be exposed to sound levels 
that would result in Level A or Level B harassment, radial distances 
from the airgun array to predicted isopleths corresponding to the Level 
A harassment and Level B harassment thresholds are calculated, as 
described above. Those radial distances are then used to calculate the 
area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the Level A and Level B harassment thresholds. The 
distance for the 160-dB threshold (based on L-DEO model results) was 
used to draw a buffer around every transect line in GIS to determine 
the total ensonified area in each depth category. Estimated incidents 
of exposure above Level A and Level B harassment criteria are presented 
in Table 6. For additional details regarding calculations of ensonified 
area, please see Appendix D of L-DEO's application. 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 proposed 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 proposed for authorization. Estimated 
exposures and proposed take numbers for authorization 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 propose to authorize take accordingly. Note 
that the aforementioned modification to certain tracklines to maintain 
a larger buffer around specific Steller sea lion haul-outs and 
rookeries has not been accounted for in the take estimation process 
and, therefore, actual acoustic exposures of Steller sea lions above 
harassment thresholds would likely be less than assumed here.

                                Table 6--Estimated Taking by Level A and Level B Harassment, and Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                             Estimated    Estimated     Proposed     Proposed
                   Species                              Stock \1\             level B      level A      level B      level A     Total take   Percent of
                                                                             harassment   harassment   harassment   harassment                stock \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Pacific right whale \2\...............  ............................            1            0            2            0            2          6.5
Humpback whale..............................  WNP.........................        2,580          140        2,580          140        2,719        245.6
                                              CNP.........................  ...........  ...........  ...........  ...........  ...........         26.9
Blue whale..................................  ............................           25            2           25            2           27          1.8
Fin whale \5\...............................  ............................        2,037          118        2,037          118        2,155          n/a
Sei whale...................................  ............................            5            0            5            0            5            1
Minke whale \5\.............................  ............................           30            2           30            2           32          n/a
Gray whale..................................  ENP.........................          223            3          223            3          226          0.8
                                              WNP.........................            3            0            3            0            3            1
Sperm whale \5\.............................  ............................           39            3           42            0           42          n/a
Baird's beaked whale \5\....................  ............................           25            2           27            0           27          n/a
Stejneger's beaked whale \5\................  ............................           43            3           46            0           46          n/a
Cuvier's beaked whale \5\...................  ............................          110            7          117            0          117          n/a
Pacific white-sided dolphin.................  ............................        1,038           64        1,103            0        1,103          4.1
Northern right whale dolphin \3\............  ............................  ...........  ...........           58            0           58          0.2
Risso's dolphin \3\.........................  ............................            1            0           22            0           22          0.3
Killer whale................................  Offshore....................          159            9          169            0          169         56.3
                                              Transient...................  ...........  ...........  ...........  ...........  ...........         28.8
                                              Resident....................  ...........  ...........  ...........  ...........  ...........          7.2
Dall's porpoise.............................  ............................        5,424          308        5,424          308        5,732          6.9
Harbor porpoise.............................  ............................          935           51          935           51          985            2
Northern fur seal...........................  ............................          809           51          860            0          860          0.1
Steller sea lion............................  ............................          489           30          520            0          520            1
Northern elephant seal......................  ............................          110            7          117            0          117          0.1
Harbor seal.................................  ............................          198           11          209            0          209          3.7
Spotted seal \4\............................  ............................  ...........  ...........            5            0            5          0.0
Ribbon seal \4\.............................  ............................  ...........  ...........            5            0            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 proposed takes occurred within each stock. Where necessary, additional discussion is provided in the ``Small Numbers Analysis''
  section.
\2\ Estimated exposure of one whale increased to group size of two (Shelden et al., 2005; Waite et al., 2003; Wade et al., 2011.
\3\ L-DEO requests authorization of northern right whale dolphin take equivalent to exposure of one group, and estimated exposure of one Risso's dolphin
  increased to group size of 22 (Barlow, 2016).
\4\ L-DEO requests 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 45402]]

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    In order to satisfy the MMPA's least practicable adverse impact 
standard, NMFS has evaluated a suite of basic mitigation protocols for 
seismic surveys that are required regardless of the status of a stock. 
Additional or enhanced protections may be required for species whose 
stocks are in particularly poor health and/or are subject to some 
significant additional stressor that lessens that stock's ability to 
weather the effects of the specified activities without worsening its 
status. We reviewed seismic mitigation protocols required or 
recommended elsewhere (e.g., HESS, 1999; DOC, 2013; IBAMA, 2018; Kyhn 
et al., 2011; JNCC, 2017; DEWHA, 2008; BOEM, 2016; DFO, 2008; GHFS, 
2015; MMOA, 2016; Nowacek et al., 2013; Nowacek and Southall, 2016), 
recommendations received during public comment periods for previous 
actions, and the available scientific literature. We also considered 
recommendations given in a number of review articles (e.g., Weir and 
Dolman, 2007; Compton et al., 2008; Parsons et al., 2009; Wright and 
Cosentino, 2015; Stone, 2015b). This exhaustive review and 
consideration of public comments regarding previous, similar activities 
has led to development of the protocols included here.
    As described previously, L-DEO has 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-foot (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 PSOs) 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 Protected Species 
Observers (PSOs). The PSOs must have no tasks other than to conduct 
observational effort, record observational data, and communicate with 
and instruct relevant vessel crew with regard to the presence of marine 
mammals and mitigation requirements. PSO resumes shall be provided to 
NMFS for approval.
    At least one of the visual and two of the acoustic PSOs (discussed 
below) aboard the vessel must have a minimum of 90 days at-sea 
experience working in those roles, respectively, 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

[[Page 45403]]

(rather than being based on the center of the array or around the 
vessel itself). During use of the acoustic source (i.e., anytime 
airguns are active, including ramp-up), detections of marine mammals 
within the buffer zone (but outside the exclusion zone) shall be 
communicated to the operator to prepare for the potential shutdown of 
the acoustic source.
    During use of the airgun (i.e., anytime the acoustic source is 
active, including ramp-up), detections of marine mammals within the 
buffer zone (but outside the exclusion zone) should be communicated to 
the operator to prepare for the potential shutdown of the acoustic 
source. Visual PSOs will immediately communicate all observations to 
the on duty acoustic PSO(s), including any determination by the PSO 
regarding species identification, distance, and bearing and the degree 
of confidence in the determination. Any observations of marine mammals 
by crew members shall be relayed to the PSO team. During good 
conditions (e.g., daylight hours; Beaufort sea state (BSS) 3 or less), 
visual PSOs shall conduct observations when the acoustic source is not 
operating for comparison of sighting rates and behavior with and 
without use of the acoustic source and between acquisition periods, to 
the maximum extent practicable.
    Visual PSOs may be on watch for a maximum of four consecutive hours 
followed by a break of at least one hour between watches and may 
conduct a maximum of 12 hours of observation per 24-hour period. 
Combined observational duties (visual and acoustic but not at same 
time) may not exceed 12 hours per 24-hour period for any individual 
PSO.

Passive Acoustic Monitoring

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

[[Page 45404]]

the acoustic source. All operators must adhere to the following pre-
clearance and ramp-up requirements:
     The operator must notify a designated PSO of the planned 
start of ramp-up as agreed upon with the lead PSO; the notification 
time should not be less than 60 minutes prior to the planned ramp-up in 
order to allow the PSOs time to monitor the exclusion and buffer zones 
for 30 minutes prior to the initiation of ramp-up (pre-clearance);
     Ramp-ups shall be scheduled so as to minimize the time 
spent with the source activated prior to reaching the designated run-
in;
     One of the PSOs conducting pre-clearance observations must 
be notified again immediately prior to initiating ramp-up procedures 
and the operator must receive confirmation from the PSO to proceed;
     Ramp-up may not be initiated if any marine mammal is 
within the applicable exclusion or buffer zone. If a marine mammal is 
observed within the applicable exclusion zone or the buffer zone during 
the 30 minute pre-clearance period, ramp-up may not begin until the 
animal(s) has been observed exiting the zones or until an additional 
time period has elapsed with no further sightings (15 minutes for small 
odontocetes and pinnipeds, and 30 minutes for all mysticetes and all 
other odontocetes, including sperm whales, beaked whales, and large 
delphinids, such as killer whales);
     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 would not resume until the 
marine mammal has cleared the 500-m EZ. The animal would be considered 
to have cleared the 500-m EZ if it is visually observed to have 
departed the 500-m EZ, or it has not been seen within the 500-m EZ for 
15 min in the case of small odontocetes and pinnipeds, or 30 min in the 
case of mysticetes and large odontocetes, including sperm whales, 
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., permanent threshold 
shift).
    A large body of anecdotal evidence indicates that small dolphins 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinoids (e.g., Barkaszi et al., 2012, 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

[[Page 45405]]

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 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 preliminarily determined that the mitigation measures provide 
the means effecting the least practicable impact on the affected 
species or stocks and their habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance.

Proposed Monitoring and Reporting

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

[[Page 45406]]

Vessel-Based Visual Monitoring

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

[[Page 45407]]

     Animal's closest point of approach (CPA) and/or closest 
distance from any element of the acoustic source;
     Platform activity at time of sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other); and
     Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up) and time and location of the 
action.
    If a marine mammal is detected while using the PAM system, the 
following information should be recorded:
     An acoustic encounter identification number, and whether 
the detection was linked with a visual sighting;
     Date and time when first and last heard;
     Types and nature of sounds heard (e.g., clicks, whistles, 
creaks, burst pulses, continuous, sporadic, strength of signal); and
     Any additional information recorded such as water depth of 
the hydrophone array, bearing of the animal to the vessel (if 
determinable), species or taxonomic group (if determinable), 
spectrogram screenshot, and any other notable information.

Reporting

    A report would be submitted to NMFS within 90 days after the end of 
the cruise. The report would describe the operations that were 
conducted and sightings of marine mammals near the operations. The 
report would provide full documentation of methods, results, and 
interpretation pertaining to all monitoring. The 90-day report would 
summarize the dates and locations of seismic operations, and all marine 
mammal sightings (dates, times, locations, activities, associated 
seismic survey activities).
    The 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

[[Page 45408]]

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 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 would be authorized. Similarly, non-auditory 
physical effects, stranding, and vessel strike are not expected to 
occur.
    We are proposing to authorize a limited number of instances of 
Level A harassment of 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-foot (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

[[Page 45409]]

there would be, at worst, minimal impacts to animals and habitat within 
these areas.

Negligible Impact Conclusions

    The proposed survey would be of short duration (16 days of seismic 
operations), and the acoustic ``footprint'' of the proposed survey 
would be small relative to the ranges of the marine mammals that would 
potentially be affected. Sound levels would increase in the marine 
environment in a relatively small area surrounding the vessel compared 
to the range of the marine mammals within the proposed survey area. 
Short term exposures to survey operations are not likely to 
significantly disrupt marine mammal behavior, and the potential for 
longer-term avoidance of important areas is limited. The 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 proposed mitigation measures are expected to reduce the number 
and/or severity of takes by allowing for detection of marine mammals in 
the vicinity of the vessel by visual and acoustic observers, and by 
minimizing the severity of any potential exposures via shutdowns of the 
airgun array. Based on previous monitoring reports for substantially 
similar activities that have been previously authorized by NMFS, we 
expect that the proposed mitigation will be effective in preventing, at 
least to some extent, potential PTS in marine mammals that may 
otherwise occur in the absence of the proposed mitigation (although all 
authorized PTS has been accounted for in this analysis).
    NMFS concludes that exposures to marine mammal species and stocks 
due to L-DEO's proposed survey would result in only short-term 
(temporary and short in duration) effects to individuals exposed, over 
relatively small areas of the affected animals' ranges. Animals may 
temporarily avoid the immediate area, but are not expected to 
permanently abandon the area. Major shifts in habitat use, 
distribution, or foraging success are not expected. NMFS does not 
anticipate the proposed take estimates to impact annual rates of 
recruitment or survival.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or proposed 
to be authorized;
     The proposed activity is temporary and of relatively short 
duration (16 days);
     The anticipated impacts of the proposed activity on marine 
mammals would primarily be temporary behavioral changes due to 
avoidance of the area around the survey vessel;
     The number of instances of potential PTS that may occur 
are expected to be very small in number. Instances of potential PTS 
that are incurred in marine mammals are expected to be of a low level, 
due to constant movement of the vessel and of the marine mammals in the 
area, and the nature of the survey design (not concentrated in areas of 
high marine mammal concentration);
     The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the proposed survey to avoid exposure to sounds from the activity;
     The potential adverse effects on fish or invertebrate 
species that serve as prey species for marine mammals from the proposed 
survey would be temporary and spatially limited, and impacts to marine 
mammal foraging would be minimal; and
     The proposed mitigation measures, including visual and 
acoustic monitoring, shutdowns, and 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 proposed mitigation and 
monitoring measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. 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, three 
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 proposed take is less than one-third of the best 
available stock abundance (recognizing that some of those takes may be 
repeats of the same individual, thus rendering the actual percentage 
even lower).
    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 proposed 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 (2,719 take 
incidents) would be 18.5 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 57 takes should be expected 
to accrue to the stock (or approximately 5 percent of the 2006 
abundance estimate for the WNP stock). This information supports a 
preliminary determination that the take proposed for authorization for 
humpback whales would be of no greater than small numbers, for any 
stock.

[[Page 45410]]

    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 whales. 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 proposed take number of 32 
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 15.8 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 
proposed take number of 159 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 27-117) that can 
safely assume that they are small relative to any reasonable assumption 
of likely population abundance for these stocks.
    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 56.5 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 proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals will be taken relative to the population size 
of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There is some sealing by indigenous groups in the proposed survey 
area in the Aleutian Islands. However, given the temporary nature of 
the proposed activities and the fact that all operations would occur 
more than 3 nmi from shore, the proposed 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 
preliminarily determined that the total taking of affected species or 
stocks would not have an unmitigable adverse impact on the availability 
of such species or stocks for taking for subsistence purposes.

Endangered Species Act (ESA)

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

Proposed Authorization

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

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of Proposed IHA for the proposed 
geophysical survey. We also request at this time comment on the 
potential Renewal of this proposed IHA as described in the paragraph 
below. Please include with your comments any supporting data or 
literature citations to help inform decisions on the request for this 
IHA or a subsequent Renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time, one-year 
Renewal IHA following notice to the public providing an additional 15 
days for public comments when (1) up to another year of identical, or 
nearly identical, activities as described in the Specified Activities 
section of this notice is planned or (2) the activities as described in 
the Specified Activities section of this notice would not be completed 
by the time the IHA expires and a Renewal would allow for completion of 
the activities beyond that described in the Dates and Duration section 
of this notice, provided all of the following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed Renewal IHA effective date (recognizing that the 
Renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA);
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested Renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with

[[Page 45411]]

the exception of reducing the type or amount of take); and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
     Upon review of the request for Renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: July 22, 2020.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2020-16322 Filed 7-27-20; 8:45 am]
BILLING CODE 3510-22-P