Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Low-Energy Geophysical Survey in the Northeastern Pacific Ocean, 39276-39307 [2017-17378]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 82, Number 158 (Thursday, August 17, 2017)]
[Notices]
[Pages 39276-39307]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-17378]



[[Page 39275]]

Vol. 82

Thursday,

No. 158

August 17, 2017

Part III





Department of Commerce





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National Oceanic and Atmospheric Administration





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 Takes of Marine Mammals Incidental to Specified Activities; Taking 
Marine Mammals Incidental to a Low-Energy Geophysical Survey in the 
Northeastern Pacific Ocean; Notice

Federal Register / Vol. 82 , No. 158 / Thursday, August 17, 2017 / 
Notices

[[Page 39276]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XF329


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Low-Energy Geophysical Survey in 
the Northeastern Pacific Ocean

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

ACTION: Notice; proposed incidental harassment authorization; request 
for comments.

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SUMMARY: NMFS has received a request from the Scripps Institution of 
Oceanography (SIO) for authorization to take marine mammals incidental 
to a low-energy marine geophysical survey in the northeastern Pacific 
Ocean. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is 
requesting comments on its proposal to issue an incidental harassment 
authorization (IHA) to incidentally take marine mammals during the 
specified activities. NMFS will consider public comments prior to 
making any final decision on the issuance of the requested MMPA 
authorization and agency responses will be summarized in the final 
notice of our decision.

DATES: Comments and information must be received no later than 
September 18, 2017.

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 ITP.Carduner@noaa.gov.
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments received electronically, including 
all attachments, must not exceed a 25-megabyte file size. Attachments 
to electronic comments will be accepted in Microsoft Word or Excel or 
Adobe PDF file formats only. All comments received are a part of the 
public record and will generally be posted online at www.nmfs.noaa.gov/pr/permits/incidental/research.htm 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: Jordan Carduner, 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.nmfs.noaa.gov/pr/permits/incidental/research.htm. In case of problems accessing these documents, 
please call the contact listed above.

SUPPLEMENTARY INFORMATION: 

Background

    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 
authorization is provided to the public for review.
    An authorization for incidental takings shall be granted if NMFS 
finds that the taking will have a negligible impact on the species or 
stock(s), will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for subsistence uses (where 
relevant), and if the permissible methods of taking and requirements 
pertaining to the mitigation, monitoring and reporting of such takings 
are set forth.
    NMFS has defined ``negligible impact'' in 50 CFR 216.103 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.
    The MMPA states that the term ``take'' means to harass, hunt, 
capture, kill or attempt to harass, hunt, capture, or kill any marine 
mammal.
    Except with respect to certain activities not pertinent here, 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).

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 is preparing an 
Environmental Assessment (EA) to consider the environmental impacts 
associated with the issuance of the proposed IHA. NMFS' EA is available 
at www.nmfs.noaa.gov/pr/permits/incidental/research.htm. 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 20, 2017, NMFS received a request from SIO for an IHA to 
take marine mammals incidental to conducting a low-energy marine 
geophysical survey in the northeastern Pacific Ocean. On July 5, 2017, 
we deemed SIO's application for authorization to be adequate and 
complete. SIO's request is for take of a small number of 27 species of 
marine mammals by Level B harassment and Level A harassment. Neither 
SIO nor NMFS expects mortality to result from this activity, and, 
therefore, an IHA is appropriate. The planned activity is not expected 
to exceed one year, hence, we do not expect subsequent MMPA incidental 
harassment authorizations would be issued for this particular activity.

Description of Proposed Activity

Overview

    SIO proposes to conduct a low-energy marine seismic survey offshore 
Oregon and Washington in the northeastern Pacific Ocean over the course 
of five days in September 2017. The proposed survey would occur off the 
Oregon continental margin out to 127.5[deg] W. and between ~43 and 
46.5[deg] N. (See Figure 1 in IHA application). Water depths in the 
survey area are ~130-2600 m. The proposed survey would involve one 
source vessel, the R/V Roger Revelle. The Revelle would tow a pair of 
45 cubic inch (in\3\) airguns with a total discharge volume of ~90 
in\3\ as an energy source along predetermined lines.

Dates and Duration

    The seismic survey would be carried out for five days. The Revelle 
would likely depart from Newport, Oregon, on

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or about September 22, 2017 and would return to Newport on or about 
September 29, 2017. Some deviation in timing could result from 
unforeseen events such as weather, logistical issues, or mechanical 
issues with the research vessel and/or equipment. Seismic activities 
would occur 24 hours per day during the proposed survey.

Specific Geographic Region

    The survey would occur in the northeastern Pacific Ocean off the 
Oregon continental margin out to 127.5[deg] W. and between ~43 and 
46.5[deg] N. Two potential survey areas off the Oregon continental 
margin have been proposed (See Figure 1 in IHA application). One 
potential survey area, referred to by SIO as the Astoria Fan area, is 
located off northern Oregon off the mouth of the Columbia River and 
near the Astoria Canyon. The other potential survey area, referred to 
as the southern Oregon area, is located off the southern Oregon margin. 
Both the proposed Astoria Fan and Southern Oregon survey areas are 
located at least 23 kilometers (km) from the U.S. west coast over water 
depths ~130-2600 meters (m). SIO will ultimately select one of these 
two potential areas for the survey (i.e., both areas will not be 
surveyed). Representative survey track lines for both potential survey 
areas are shown in Figure 1 of the IHA application. The Revelle would 
depart from Newport, Oregon and return to Newport at the conclusion of 
the survey.

Detailed Description of Specific Activity

    SIO plans to conduct a low-energy seismic survey off the coasts of 
Oregon and Washington. The proposed surveys involve an Early Career 
Seismic Chief Scientist Training Cruise which aims to train scientists 
on how to effectively plan seismic surveys, acquire data, and manage 
activities at sea. In addition, the survey would provide critical data 
to understand the sediment and crustal structure within the Cascadia 
continental margin. The proposed survey would take place on the active 
continental margin of the U.S. west coast where a variety of 
sedimentary and tectonic settings are available, providing many targets 
of geologic interest to a wide range of research cruise participants.
    The procedures to be used for the seismic survey would be similar 
to those used during previous seismic surveys by SIO and would use 
conventional seismic methodology. The survey would involve one source 
vessel, the R/V Roger Revelle. The Revelle would deploy a pair of 45-
in\3\ GI airguns as an energy source with a total discharge volume of 
~90 in\3\. The receiving system would consist of one 800-m hydrophone 
streamer. As the airguns are towed along the survey lines, the 
hydrophone streamer would receive the returning acoustic signals and 
transfer the data to the on-board processing system.
    Two potential sites off the Oregon continental margin, referred to 
by SIO as the Astoria Fan and southern Oregon sites, have been proposed 
for the survey (see Figure 1 in the IHA application). Only one of the 
two sites will be surveyed. Each of the proposed survey sites has 
several science targets. The southern Oregon survey includes the paleo 
objectives, a long plate transect that crosses Diebold Knoll, and a 
detailed survey of the megaslump segment of the Cascadia subduction 
zone, which has no previous seismic data. The Astoria Fan survey 
includes flexure, accretionary wedge mechanisms and gas hydrates as 
objectives; it covers a major seismic gap. The scientists on board 
would be responsible for modifying the survey to fit the allocated 
cruise length while meeting the project objectives, including choosing 
which survey or what portion of each survey to conduct.
    The total line km for the Southern Oregon survey would be 1013 km, 
~5 percent of which would be in intermediate water (100-1000 m), with 
the remainder in water deeper than 1000 m. The total length for the 
Astoria Fan survey would be 1057 km, with ~23 percent of line km in 
intermediate water and the remainder in water >1000 m. No effort during 
either survey would occur in shallow water <100 m deep. For purposes of 
this proposed IHA, the total track distance to be surveyed is estimated 
to be no greater than ~1057 km, which is the line km of the longer of 
the two potential surveys. There would be additional seismic operations 
in the survey area associated with airgun testing and repeat coverage 
of any areas where initial data quality is sub-standard. To account for 
these additional seismic operations, 25 percent has been added in the 
form of operational days, which is equivalent to adding 25 percent to 
the proposed line km to be surveyed.
    In addition to the operations of the airgun array, a multibeam 
echosounder (MBES) and a sub-bottom profiler (SBP) would also be 
operated from the Revelle continuously throughout the seismic survey, 
but not during transits to and from the project area. All planned 
geophysical data acquisition activities would be conducted by SIO with 
on-board assistance by the scientists who have proposed the study. The 
vessel would be self-contained, and the crew would live aboard the 
vessel for the entire cruise.
    The Revelle has a length of 83 m, a beam of 16.0 m, and a maximum 
draft of 5.2 m. The ship is powered by two 3,000 horsepower Propulsion 
General Electric motors and an 1180-hp azimuthing jet bow thruster. An 
operation speed of 9.3 km/h (5 knots (kt)) would be used during seismic 
acquisition. When not towing seismic survey gear, the Revelle cruises 
at 22.2-23.1 km/h (12-12.5 kt) and has a maximum speed of 27.8 km/h (15 
kt). The Revelle would also serve as the platform from which vessel-
based protected species observers (PSOs) would watch for marine mammals 
during airgun operations.
    During the survey, The Revelle would tow a pair of 45-in\3\ GI 
airguns and an 800 m streamer containing hydrophones along 
predetermined lines. Seismic pulses would be emitted at intervals of 
~8-10 seconds (s) (20-25 m). The generator chamber of each GI gun, the 
one responsible for introducing the sound pulse into the ocean, is 45 
in\3\. The two 45-in\3\ GI guns would be towed 21 m behind the Revelle, 
2 m apart side by side, at a depth of 3 m. As the airguns are towed 
along the survey lines, the towed hydrophone array in the 800 m 
streamer would receive the reflected signals and transfer the data to 
the onboard processing system.

         Table 1--Specifications of the R/V Revelle Airgun Array
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Number of airguns........................  2.
Tow depth of energy source...............  3 m.
Dominant frequency components............  0-188 Hz.
Total volume.............................  ~90 in\3\.
Shot interval............................  7.8 seconds.
------------------------------------------------------------------------

    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

    Section 4 of the application summarizes 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' Stock Assessment Reports (SAR; www.nmfs.noaa.gov/pr/sars/), and more general information about these species (e.g., 
physical and behavioral descriptions) may be found on NMFS'

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Web site (www.nmfs.noaa.gov/pr/species/mammals/).
    Table 2 lists all species with expected potential for occurrence in 
the northeastern Pacific Ocean 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 (2016). PBR is defined by the MMPA as 
the maximum number of animals, not including natural mortalities, that 
may be removed from a marine mammal stock while allowing that stock to 
reach or maintain its optimum sustainable population (as described in 
NMFS' SARs). While no 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' 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' U.S. Pacific SARs (e.g., Carretta et al. 2017). All values 
presented in Table 2 are the most recent available at the time of 
publication and are available in the 2017 SARs (Carretta et al. 2017), 
available online at: www.nmfs.noaa.gov/pr/sars, except where noted 
otherwise.

                          Table 2--Marine Mammals That Could Occur in the Project Area
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                                                                    Stock abundance
                                                      ESA/MMPA      \2\ (CV, Nmin,                  Relative
            Species                   Stock           status;         most recent     PBR \4\     occurrence in
                                                  strategic (Y/N)      abundance                  project area
                                                        \1\           survey) \3\
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                      Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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                                             Family: Balaenopteridae
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North Pacific right whale \5\   Eastern North     E/D; Y           31..............        0.1  Rare.
 (Eubalaena japonica).           Pacific.
Gray whale \5\ (Eschrichtius    Eastern North     -/-; N           20,990 (0.05;           3.1  Common in
 robustus).                      Pacific.                           20,125; 2011).               nearshore
                                                                                                 areas, rare
                                                                                                 elsewhere.
Humpback whale \6\ (Megaptera   California/       E/T/D; N         1,918 (0.03;             11  Common in
 novaeangliae).                  Oregon/                            1,876; 2014).                nearshore
                                 Washington.                                                     areas, rare
                                                                                                 elsewhere.
Minke whale (Balaenoptera       California/       -/-; N           636 (0.72; 369;         3.5  Rare.
 acutorostrata).                 Oregon/                            2014).
                                 Washington.
Sei whale (Balaenoptera         Eastern N         E/D; Y           519 (0.4; 374;         0.75  Rare.
 borealis).                      Pacific.                           2014).
Fin whale (Balaenoptera         California/       E/D; Y           9,029 (0.12;             81  Common.
 physalus.                       Oregon/                            8,127; 2014).
                                 Washington.
Blue whale (Balaenoptera        Eastern N         E/D; Y           1,647 (0.07;            2.3  Rare.
 musculus).                      Pacific.                           1,551; 2011).
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        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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                                              Family: Physeteridae
----------------------------------------------------------------------------------------------------------------
Sperm whale (Physeter           California/       E/D; Y           2,106 (0.58;            2.7  Common.
 macrocephalus).                 Oregon/                            1,332; 2014)..
                                 Washington.
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        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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                                                Family: Kogiidae
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Pygmy sperm whale (Kogia        California/       -/-; N           4,111 (1.12;             19  Rare.
 breviceps).                     Oregon/                            1,924; 2014).
                                 Washington.
Dwarf sperm whale (Kogia sima)  California/       -/-; N           unknown               Undet  Rare.
                                 Oregon/                            (unknown;
                                 Washington.                        unknown; 2014).
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        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
----------------------------------------------------------------------------------------------------------------
                                               Family delphinidae
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Killer whale (Orcinus orca)...  West coast        -/-; N           243 (n/a; 243;          2.4  Rare.
                                 transient.                         2009).
                                Eastern North     -/-; N           240 (0.49; 162;         1.6  Rare.
                                 Pacific                            2014).
                                 offshore.
False killer whale \7\          Hawaii Pelagic..  -/-; N           1,540 (0.66;            9.3  Rare.
 (Pseudorca crassidens).                                            928; 2010).
Short-finned pilot whale        California/       -/-; N           836 (0.79; 466;         4.5  Rare.
 (Globicephala macrorhynchus).   Oregon/                            2014).
                                 Washington.
Harbor porpoise (Phocoena       Northern Oregon/  -/-; N           21,487 (0.44;           151  Abundant.
 phocoena).                      Washington                         15,123; 2011).
                                 Coast.
                                Northern          -/-; N           35,769 (0.52;           475  Abundant.
                                 California/                        23,749; 2011).
                                 Southern Oregon.

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Dall's porpoise (Phocoena       California/       -/-; N           25,750 (0.45;           172  Abundant.
 dalli).                         Oregon/                            17,954; 2014).
                                 Washington.
Bottlenose dolphin (Tursiops    California/       -/-; N           1,924 (0.54;             11  Rare.
 truncatus).                     Oregon/                            1,255; 2014).
                                 Washington
                                 Offshore.
Striped dolphin (Stenella       California/       -/-; N           29,211 (0.2;            238  Rare.
 coeruleoala).                   Oregon/                            24,782; 2014).
                                 Washington.
Risso's dolphin (Grampus        California/       -/-; N           6,336 (0.32;             46  Common.
 griseus).                       Oregon/                            4,817; 2014).
                                 Washington.
Short-beaked common dolphin     California/       -; N             969,861 (0.17;        8,393  Common.
 (Delphinus delphis).            Oregon/                            839,325; 2014).
                                 Washington.
Pacific white-sided dolphin     California/       -; N             26,814 (0.28;           191  Abundant.
 (Lagenorhynchus obliquidens).   Oregon/                            21,195; 2014).
                                 Washington.
Northern right whale dolphin    California/       -; N             26,556 (0.44;           179  Common.
 (Lissodelphis borealis).        Oregon/                            18,608; 2014).
                                 Washington.
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        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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                                                Family: Ziphiidae
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Cuvier's beaked whale (Ziphius  California/       -/-; N           6,590 (0.55;             45  Common.
 cavirostris).                   Oregon/                            4,481; 2008).
                                 Washington.
Baird's beaked whale            California/       -; N             847 (0.81; 466;         4.7  Common.
 (Berardius bairdii).            Oregon/                            2008).
                                 Washington.
Mesoplodont beaked whales \8\.  California/       -/-; N           694 (0.65; 389;         3.9  Rare.
                                 Oregon/                            2008).
                                 Washington.
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                                     Order Carnivora--Superfamily Pinnipedia
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                                  Family Otariidae (eared seals and sea lions)
----------------------------------------------------------------------------------------------------------------
California sea lion (Zalophus   U.S.............  -; N             296,750 (n/a;         9,200  Rare.
 californianus).                                                    153,337; 2011).
Steller sea lion (Eumetopias    Eastern U.S.....  -; N             41,638 (n/a;          2,498  Common in
 jubatus).                                                          41,638; 2015).               nearshore
                                                                                                 areas, rare
                                                                                                 elsewhere.
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                                         Family Phocidae (earless seals)
----------------------------------------------------------------------------------------------------------------
Harbor seal \9\ (Phoca          Oregon/           -; N             24,732 (unk;        Unknown  Common in
 vitulina).                      Washington                         unk; n/a).                   nearshore
                                 Coast.                                                          areas, rare
                                                                                                 elsewhere.
Northern elephant seal          California        -; N             179,000 (n/a;         4,882  Common in
 (Mirounga angustirostris).      breeding.                          81,368; 2010).               nearshore
                                                                                                 areas, rare
                                                                                                 elsewhere.
Northern fur seal (Callorhinus  California......  -; N             14,050 (n/a;            451  Common in
 ursinus).                                                          7,524; 2013).                nearshore
                                                                                                 areas, rare
                                                                                                 elsewhere.
----------------------------------------------------------------------------------------------------------------
\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 (see footnote
  3) 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\ Abundance estimates from Carretta et al. (2017) unless otherwise noted.
\3\ CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not
  applicable. For certain stocks, abundance estimates are actual counts of animals and there is no associated
  CV. The most recent abundance survey that is reflected in the abundance estimate is presented; there may be
  more recent surveys that have not yet been incorporated into the estimate.
\4\ Potential biological removal (PBR), 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 size (OSP).
\5\ Values for gray whale and North Pacific right whale are from Muto et al. 2016.
\6\ Humpback whales in the survey area could originate from either the ESA threatened Mexico DPS or from the ESA
  endangered Central America DPS.
\7\ NMFS does not have a defined stock for false killer whales off the West Coast of the U.S. as they are
  considered uncommon visitors to the area; any false killer whales observed off the West Coast of the U.S.
  would likely be part of the eastern North Pacific population. Of the stocks defined by NMFS, the Hawaii
  Pelagic stock is the most likely to include individuals in the eastern North Pacific population.
\8\ Includes the following species: Blainville's beaked whale (M. densirostris), Perrin's beaked whale (M.
  perrini), Lesser beaked whale (M. peruvianus), Stejneger's beaked whale (M. stejnegeri), Gingko-toothed beaked
  whale (M. gingkodens), and Hubbs' beaked whale (M. carlhubbsi).
\9\ The most recent abundance estimate is from 1999. This is the best available information, but because this
  abundance estimate is >8 years old, there is no current estimate of abundance available for this stock.

    All species that could potentially occur in the proposed survey 
area are included in Table 2. However, as described below, the spatial 
occurrence of the North Pacific right whale and dwarf sperm whale are 
such that take is

[[Page 39280]]

not expected to occur for these species. The North Pacific right whale 
is one of the most endangered species of whale in the world (Carretta 
et al. 2017). Only 82 sightings of right whales in the entire eastern 
North Pacific were reported from 1962 to 1999, with the majority of 
these occurring in the Bering Sea and adjacent areas of the Aleutian 
Islands (Brownell et al. 2001). Most sightings in the past 20 years 
have occurred in the southeastern Bering Sea, with a few in the Gulf of 
Alaska (Wade et al. 2011). Despite many miles of systematic aerial and 
ship-based surveys for marine mammals off the coasts of Washington, 
Oregon and California over several years, only seven documented 
sightings of right whales were made from 1990 to 2000 (Waite et al. 
2003). Because of the small population size and the fact that North 
Pacific right whales spend the summer feeding in high latitudes, the 
likelihood that the proposed survey would encounter a North Pacific 
right whale is discountable. Along the U.S. west coast, no at-sea 
sightings of dwarf sperm whales have ever been reported despite 
numerous vessel surveys of this region (Barlow 1995; Barlow and 
Gerrodette 1996; Barlow and Forney 2007; Forney 2007; Barlow 2010, 
Barlow 2016). Therefore, based on the best available information, we 
believe the likelihood of the survey encountering a dwarf sperm whale 
is discountable. SIO requested authorization for the incidental take of 
dwarf sperm whales (the request was for a combined two takes of pygmy 
and/or dwarf sperm whales). However as we have determined the 
likelihood of take of dwarf sperm whales is discountable, we do not 
propose to authorize take of dwarf sperm whales. Thus, the North 
Pacific right whale and dwarf sperm whale are not discussed further in 
this document.
    We have reviewed SIO's species descriptions, including life history 
information, distribution, regional distribution, diving behavior, and 
acoustics and hearing, for accuracy and completeness. We refer the 
reader to Section 4 of SIO's IHA application, rather than reprinting 
the information here. Below, for the 27 species that are likely to be 
taken by the activities described, we offer a brief introduction to the 
species and relevant stock(s) as well as available information 
regarding population trends and threats, and describe any information 
regarding local occurrence.

Humpback Whale

    Humpback whales are found worldwide in all ocean basins. In winter, 
most humpback whales occur in the subtropical and tropical waters of 
the Northern and Southern Hemispheres (Muto et al., 2015). These 
wintering grounds are used for mating, giving birth, and nursing new 
calves. Humpback whales migrate nearly 3,000 mi (4,830 km) from their 
winter breeding grounds to their summer foraging grounds in Alaska. The 
humpback whale is the most common species of large cetacean reported 
off the coasts of Oregon and Washington from May to November (Green et 
al. 1992; Calambokidis et al. 2004).
    There are five stocks of humpback whales, one of which occurs along 
the U.S. west coast: The California/Oregon/Washington Stock, which 
includes animals that appear to be part of two separate feeding groups, 
a California and Oregon feeding group and a northern Washington and 
southern British Columbia feeding group (Calambokidis et al. 2008, 
Barlow et al. 2011). Very few photographic matches between these 
feeding groups have been documented (Calambokidis et al. 2008). 
Humpbacks from both groups have been photographically matched to 
breeding areas off Central America, mainland Mexico, and Baja 
California, but whales from the northern Washington and southern 
British Columbia feeding group also winter near the Hawaiian Islands 
and the Revillagigedo Islands off Mexico (Barlow et al. 2011).
    Humpback whales were listed as endangered under the Endangered 
Species Conservation Act (ESCA) in June 1970. In 1973, the ESA replaced 
the ESCA, and humpbacks continued to be listed as endangered. NMFS 
recently evaluated the status of the species, and on September 8, 2016, 
NMFS divided the species into 14 distinct population segments (DPS), 
removed the current species-level listing, and in its place listed four 
DPSs as endangered and one DPS as threatened (81 FR 62259; September 8, 
2016). The remaining nine DPSs were not listed. The Mexico DPS and the 
Central America DPS are the only DPSs that are expected to occur in the 
survey area. The Mexico DPS is listed as threatened and the Central 
America DPS is listed as endangered under the ESA (81 FR 62259; 
September 8, 2016). The California/Oregon/Washington stock is 
considered a depleted and strategic stock under the MMPA.

Blue Whale

    The blue whale has a cosmopolitan distribution and tends to be 
pelagic, only coming nearshore to feed and possibly to breed (Jefferson 
et al. 2008). Blue whale migration is less well defined than for some 
other rorquals, and their movements tend to be more closely linked to 
areas of high primary productivity, and hence prey, to meet their high 
energetic demands (Branch et al. 2007). Generally, blue whales are 
seasonal migrants between high latitudes in the summer, where they 
feed, and low latitudes in the winter, where they mate and give birth 
(Lockyer and Brown 1981). Some individuals may stay in low or high 
latitudes throughout the year (Reilly and Thayer 1990; Watkins et al. 
2000). North Pacific blue whales were once thought to belong to as many 
as five separate populations (Reeves et al. 1998), but acoustic 
evidence suggests only two populations, in the eastern and western 
North Pacific, respectively (Stafford et al. 2001, Stafford 2003, 
McDonald et al. 2006, Monnahan et al. 2014). Only the Eastern North 
Pacific stock of blue whale occurs in the proposed survey area.
    Blue whale densities along the U.S. west coast including Oregon are 
believed to be highest in shelf waters, with lower densities in deeper 
offshore areas (Becker et al. 2012; Calambokidis et al. 2015). Based on 
the absolute dynamic topography of the region, blue whales could occur 
in relatively high densities off Oregon during July-December (Pardo et 
al. 2015).
    Five blue whale sightings were reported in the proposed project 
area off Oregon/Washington during 1991-2008; one sighting occurred 
within the nearshore portion of the proposed Astoria Fan survey area, 
and four sightings occurred nearshore, east of the Southern Oregon 
survey area (Carretta et al. 2017). Hazen et al. (2016) examined blue 
whale tag data from 182 individuals along the western U.S. during 1993-
2008; multiple tag data tracks were within the proposed project area, 
particularly between August and November. Blue whales are listed as 
endangered under the ESA, and the Eastern North Pacific stock of blue 
whales is considered a depleted and strategic stock under the MMPA.

Fin Whale

    Fin whales are found throughout all oceans from tropical to polar 
latitudes. The species occurs most commonly offshore but can also be 
found in coastal areas (Aguilar 2009). Most populations migrate 
seasonally between temperate waters where mating and calving occur in 
winter, and polar waters where feeding occurs in summer (Aguilar 2009). 
However, recent evidence suggests that some animals may remain at high 
latitudes in winter or low latitudes in summer (Edwards et al. 2015).

[[Page 39281]]

    The North Pacific population summers from the Chukchi Sea to 
California and winters from California southwards (Gambell 1985). 
Aggregations of fin whales are found year-round off southern and 
central California (Dohl et al. 1980, 1983; Forney et al. 1995; Barlow 
1997) and in the summer off Oregon (Green et al. 1992; Edwards et al. 
2015). Vocalizations from fin whales have also been detected year-round 
off northern California, Oregon, and Washington (Moore et al. 1998, 
2006; Watkins et al. 2000a; Stafford et al. 2007, 2009). Fin whales are 
listed as endangered under the ESA, and the California/Oregon/
Washington stock of fin whales is considered depleted and strategic 
under the MMPA.

Sei Whale

    The sei whale occurs in all ocean basins (Horwood 2009) but appears 
to prefer mid-latitude temperate waters (Jefferson et al. 2008). It 
undertakes seasonal migrations to feed in subpolar latitudes during 
summer and returns to lower latitudes during winter to calve (Horwood 
2009). The sei whale is pelagic and generally not found in coastal 
waters (Harwood and Wilson 2001). It occurs in deeper waters 
characteristic of the continental shelf edge region (Hain et al. 1985) 
and in other regions of steep bathymetric relief such as seamounts and 
canyons (Kenney and Winn 1987; Gregr and Trites 2001).
    Sei whales are rare in the waters off California, Oregon, and 
Washington (Brueggeman et al. 1990; Green et al. 1992; Barlow 1994, 
1997). Only nine confirmed sightings were reported for California, 
Oregon, and Washington during extensive surveys from 1991-2008, 
including two within or near the westernmost portion of the Southern 
Oregon survey area (Green et al. 1992, 1993; Hill and Barlow 1992; 
Carretta and Forney 1993; Mangels and Gerrodette 1994; Von Saunder and 
Barlow 1999; Barlow 2003; Forney 2007; Barlow 2010; Carretta et al. 
2016a). Two sightings of four individuals were made from the Langseth 
seismic vessel off Washington/Oregon during June-July 2012 (RPS 2012), 
including within the proposed project area. Sei whales are listed as 
endangered under the ESA, and the Eastern North Pacific stock of sei 
whales is considered a depleted and strategic stock under the MMPA.

Minke Whale

    The minke whale has a cosmopolitan distribution ranging from the 
tropics and subtropics to the ice edge in both hemispheres (Jefferson 
et al. 2008). The California/Oregon/Washington stock of minke whale is 
the only stock that occurs in the proposed survey area. Minke whale 
sightings have been made off Oregon and Washington in shelf and deeper 
waters (Green et al. 1992; Adams et al. 2014; Carretta et al. 2017). A 
single minke whale was observed off the outer Washington coast 
(~47[deg] N.) during small boat surveys from August 2004 through 
September 2008, 14 km from shore with a bottom depth of 38 m (Oleson et 
al. 2009). One sighting was made near the Astoria Fan survey area at 
the 200-m isopleth off the mouth of the Columbia River in July 2012 
(Adams et al. 2014). Minke whales strandings have been reported in all 
seasons in Washington; most strandings (52 percent) occurred in spring 
(Norman et al. 2004). The minke whale is not listed as threatened or 
endangered under the ESA, and the California/Oregon/Washington stock is 
not listed as depleted or strategic under the MMPA.

Gray Whale

    Gray whales occur along the eastern and western margins of the 
North Pacific. During summer and fall, most whales in the Eastern North 
Pacific stock feed in the Chukchi, Beaufort and northwestern Bering 
Seas, with the exception of a relatively small number of whales 
(approximately 200) that summer and feed along the Pacific coast 
between Kodiak Island, Alaska and northern California (Carretta et al. 
2017). Three primary wintering lagoons in Baja California, Mexico are 
utilized, and some females are known to make repeated returns to 
specific lagoons (Jones 1990).
    According to predictive density distribution maps, low densities of 
gray whales could be encountered throughout the Astoria Fan and 
Southern Oregon survey areas (Menza et al. 2016). During aerial surveys 
over the shelf and slope off Oregon and Washington, gray whales were 
seen during the months of January, June-July, and September; one 
sighting was made within the Astoria Fan survey area in water >200 m 
during June 2011 (Adams et al. 2014). The proposed surveys would occur 
during the summer feeding season for gray whales in the Washington/
Oregon region. Thus, gray whales could be encountered in the eastern 
portion of the proposed project area where the water is shallower. The 
Eastern North Pacific gray whale is not listed as threatened or 
endangered under the ESA nor is it classified as a depleted or 
strategic stock under the MMPA.

Sperm Whale

    Sperm whales are widely distributed across the entire North Pacific 
and into the southern Bering Sea in summer, but the majority are 
thought to be south of 40[deg] N. in winter (Rice 1974, 1989; Gosho et 
al. 1984; Miyashita et al. 1995). They are generally distributed over 
large areas that have high secondary productivity and steep underwater 
topography, in waters at least 1000 m deep (Jaquet and Whitehead 1996; 
Whitehead 2009). Sperm whales are seen off Washington and Oregon in 
every season except winter (Green et al. 1992). Estimates of sperm 
whale abundance in California, Oregon, and Washington waters out to 300 
nautical miles ranged between 2,000 and 3,000 animals for the 1991-2008 
time series (Moore and Barlow 2014). At least five sightings during 
these surveys were within or adjacent to the Southern Oregon survey 
area, and one sighting was within the Astoria Fan survey area (Carretta 
et al. 2017). Sperm whales are listed as endangered under the ESA, and 
the California/Oregon/Washington stock is considered depleted and 
strategic under the MMPA.

Pygmy Sperm Whale

    Pygmy sperm whales are found in tropical and warm-temperate waters 
throughout the world (Ross and Leatherwood 1994) and prefer deeper 
waters with observations of this species in greater than 4,000 m depth 
(Baird et al., 2013). Along the U.S. west coast, sightings of this 
species, and of animals identified only as Kogia spp., have been rare. 
However, this probably reflects their pelagic distribution, small body 
size and cryptic behavior, rather than a measure of rarity. Barlow 
(2010) used data collected in 1991-2008 to estimate an abundance of 229 
Kogia spp. off Oregon and Washington. However, no Kogia spp. were 
sighted during surveys off Oregon and Washington in 2014 (Barlow 2016). 
Pygmy sperm whales are not listed as endangered or threatened under the 
ESA, and the California/Oregon/Washington stock is not considered 
strategic or designated as depleted under the MMPA.

Killer Whale

    Killer whales have been observed in all oceans and seas of the 
world (Leatherwood and Dahlheim 1978). Although reported from tropical 
and offshore waters (Heyning and Dahlheim 1988), killer whales prefer 
the colder waters of both hemispheres, with greatest abundances found 
within 800 km of major continents (Mitchell 1975). Along the west coast 
of North America, killer whales occur along the entire

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Alaskan coast, in British Columbia and Washington inland waterways, and 
along the outer coasts of Washington, Oregon and California (Carretta 
et al. 2017). Based on aspects of morphology, ecology, genetics and 
behavior killer whale stocks off the U.S. west coast are classified as 
either resident, transient or offshore (Ford and Fisher 1982; Baird and 
Stacey 1988; Baird et al. 1992, Hoelzel et al. 1998). The offshore 
stocks apparently do not mix with the transient and resident killer 
whale stocks found in these regions (Ford et al. 1994, Black et al. 
1997).
    Eight killer whale stocks are recognized within the Pacific U.S. 
Exclusive Economic Zone. Of these, two stocks occur in the proposed 
project area: the West Coast Transient stock which occurs from Alaska 
through California, and the Eastern North Pacific Offshore stock which 
occurs from Southeast Alaska through California. Killer whales are not 
listed as endangered or threatened under the ESA (with the exception of 
the endangered Southern Resident DPS which does not occur in the survey 
area), and the West Coast Transient stock and Eastern North Pacific 
Offshore stock are not designated as depleted or strategic under the 
MMPA.

False Killer Whale

    False killer whales are found worldwide in tropical and warm-
temperate waters (Stacey et al. 1994). In the North Pacific, this 
species occurs throughout the waters of southern Japan, Hawaii, and the 
eastern tropical Pacific. The species generally inhabits deep, offshore 
waters, but sometimes is found over the continental shelf and 
occasionally moves into very shallow water (Jefferson et al. 2008; 
Baird 2009). False killer whales are typically only observed off the 
U.S. west coast during warm-water periods. Several sightings were made 
off California during 2014-2016 when waters were unusually warm (pers. 
comm. K. Forney, NMFS Southwest Fisheries Science Center, to J. 
Carduner, NMFS, July 27, 2017). False killer whales observed in the 
survey area would be expected to originate from the eastern North 
Pacific population that is primarily found south of U.S. waters (pers. 
comm. K. Forney, NMFS Southwest Fisheries Science Center, to J. 
Carduner, NMFS, July 27, 2017). NMFS does not have a defined stock for 
false killer whales off the U.S. west coast as they are considered 
uncommon visitors to the area; any false killer whales observed off the 
U.S. west coast would likely be part of the broader eastern North 
Pacific population. Of the stocks defined by NMFS, the Hawaii Pelagic 
stock is the most likely to include individuals in the eastern North 
Pacific population. False killer whales are not listed as endangered or 
threatened under the ESA (with the exception of the endangered Main 
Hawaiian Islands insular DPS which does not occur in the survey area), 
and the Hawaii pelagic stock is not designated as depleted or strategic 
under the MMPA.

Short-Finned Pilot Whale

    Short-finned pilot whales are found in all oceans, primarily in 
tropical and warm-temperate waters (Carretta et al., 2016). The species 
prefers deeper waters, ranging from 324 m to 4,400 m, with most 
sightings between 500 m and 3,000 m (Baird 2016). The California/
Oregon/Washington Stock of short-finned pilot whales are largely 
confined to the California Current and eastern tropical Pacific. After 
a strong El Ni[ntilde]o event in 1982-83, short-finned pilot whales 
virtually disappeared from this region, and despite increased survey 
effort along the entire U.S. west coast, sightings and fishery takes 
are rare and have primarily occurred during warm-water years (Julian 
and Beeson 1998, Carretta et al. 2004, Barlow 2016). No short-finned 
pilot whales were seen during surveys off Oregon and Washington in 
1989-1990, 1992, 1996, and 2001 (Barlow 2003). A few sightings were 
made off California during surveys in 1991-2008 (Barlow 2010). 
Carrettaet al. (2017) reported two sightings off Oregon during 1991-
2008, both near the southern portion of the Astoria Fan survey area. 
Short-finned pilot whales are not listed as endangered or threatened 
under the ESA, and the California/Oregon/Washington stock is not 
considered a depleted or strategic stock under the MMPA.

Harbor Porpoise

    In the eastern North Pacific Ocean, harbor porpoise are found in 
coastal and inland waters from Point Barrow, along the Alaskan coast, 
and down the west coast of North America to Point Conception, 
California (Gaskin 1984). Harbor porpoise are known to occur year-round 
in the inland transboundary waters of Washington and British Columbia, 
Canada (Osborne et al. 1988) and along the Oregon/Washington coast 
(Barlow 1988, Barlow et al. 1988, Green et al. 1992). Based on recent 
genetic evidence (Chivers et al. 2002, 2007) there are three separate 
stocks of North Pacific harbor porpoise that occur in Oregon/Washington 
waters: a Northern California/Southern Oregon stock (Point Arena, CA, 
to Lincoln City, OR), a Northern Oregon/Washington Coast stock (Lincoln 
City, OR, to Cape Flattery, WA), and the Washington Inland Waters stock 
(in waters east of Cape Flattery). Only the Northern California/
Southern Oregon stock and Northern Oregon/Washington Coast stock occur 
in the proposed survey area.
    Harbor porpoises inhabit coastal Oregon and Washington waters year-
round, although there appear to be distinct seasonal changes in 
abundance there (Barlow 1988; Green et al. 1992). Green et al. (1992) 
reported that encounter rates were high during fall and winter, 
intermediate during spring, and low during summer. Encounter rates were 
highest along the Oregon/Washington coast in the area from Cape Blanco 
(~43[deg] N.), east of the proposed Southern Oregon survey area, to 
California, from fall through spring. During summer, the reported 
encounter rates decreased notably from inner shelf to offshore waters. 
Nearly 100 sightings were reported within or east of the proposed 
project area during aerial surveys in 2007-2012 (Forney et al. 2014). 
Two sightings of nine individuals were made from the Langseth seismic 
vessel off the southern coast of Washington during July 2012 (RPS 
2012); all sightings occurred nearshore and to the east of the Astoria 
Fan survey area. The harbor porpoise is not listed as endangered or 
threatened under the ESA and the Northern California/Southern Oregon 
stock and Northern Oregon/Washington Coast stock are not considered 
depleted or strategic stocks under the MMPA.

Dall's Porpoise

    The Dall's porpoise is distributed throughout temperate to 
subantarctic waters of the North Pacific and adjacent seas (Jefferson 
et al. 2015). Off the U.S. west coast, they are generally found along 
shelf, slope and offshore waters (Morejohn 1979). Dall's porpoise is 
likely the most abundant small cetacean in the North Pacific Ocean, and 
its abundance changes seasonally, likely in relation to water 
temperature (Becker 2007). Becker et al. (2014) projected high 
densities off southern Oregon throughout the year, with moderate 
densities to the north. According to predictive density distribution 
maps, the highest densities off southern Washington and Oregon occur 
along the 500 m isobath (Menza et al. 2016). Dall's porpoise was the 
most abundant species sighted off Oregon/Washington during 1996, 2001, 
2005, and 2008 shipboard surveys up to ~550 km from shore (Barlow 2003, 
2010) with numerous other sightings within and near the Astoria Fan and 
Southern Oregon survey areas during the summer and fall

[[Page 39283]]

(Becker et al. 2014; Carretta et al. 2016a). Dall's porpoise is not 
listed as threatened or endangered under the ESA and the California/
Oregon/Washington stock is not classified as a depleted or strategic 
stock under the MMPA.

Bottlenose Dolphin

    Bottlenose dolphins are widely distributed throughout the world in 
tropical and warm-temperate waters (Perrin et al. 2009). Generally, 
there are two distinct bottlenose dolphin ecotypes: one mainly found in 
coastal waters and one mainly found in oceanic waters (Duffield et al. 
1983; Hoelzel et al. 1998; Walker et al. 1999). As well as inhabiting 
different areas, these ecotypes differ in their diving abilities 
(Klatsky 2004) and prey types (Mead and Potter 1995). Bottlenose 
dolphins occur frequently off the coast of California, and sightings 
have been made as far north as 41[deg] N., but few records exist 
offshore Oregon and Washington (Carretta et al. 2017). Adams et al. 
(2014) made one sighting in Washington, to the north of the Astoria Fan 
survey area, during September 2012. Bottlenose dolphins are not listed 
as endangered or threatened under the ESA, and the California/Oregon/
Washington pelagic stock is not considered a depleted or strategic 
stock under the MMPA.

Striped Dolphin

    Striped dolphins are found in tropical to warm-temperate waters 
throughout the world (Carretta et al., 2016). However, in the eastern 
North Pacific, its distribution extends as far north as Washington 
(Jefferson et al. 2015). Striped dolphins are a deep water species, 
preferring depths greater than 3,500 m (Baird 2016), but have been 
observed approaching shore where there is deep water close to the coast 
(Jefferson et al. 2008). The abundance of striped dolphins off the U.S. 
west coast appears to be variable among years and could be affected by 
oceanographic conditions (Carretta et al. 2016a).
    Striped dolphins regularly occur off California (Becker et al. 
2012), where they are seen 185-556 km from the coast (Carretta et al. 
2017), though very few sightings have been made off Oregon (Barlow 
2016), and no sightings have been reported for Washington. However, 
strandings have occurred along the coasts of Oregon and Washington 
(Carretta et al. 2017). During surveys off the U.S. west coast in 2014, 
striped dolphins were seen as far north as 44[ordm] N. Striped dolphins 
are not listed as endangered or threatened under the ESA, and the 
California/Oregon/Washington stock is not considered a depleted or 
strategic stock under the MMPA.

Short-Beaked Common Dolphin

    The short-beaked common dolphin is found in tropical and warm 
temperate oceans around the world (Perrin 2009). Short-beaked common 
dolphins are the most abundant cetacean off California, and are widely 
distributed between the coast and at least 300 nautical miles from 
shore. It ranges as far south as 40[deg] S. in the Pacific Ocean, is 
common in coastal waters 200-300 m deep, and is also associated with 
prominent underwater topography, such as sea mounts (Evans 1994).
    Few sightings of short-beaked common dolphins have been made off 
Oregon, and no sightings exist for Washington waters (Carretta et al. 
2017). During surveys in 1991-2008, one sighting was made within the 
Astoria Fan survey area, and several records exist southwest of the 
Southern Oregon survey area (Carretta et al. 2017). During surveys off 
the west coast in 2014, sightings were made as far north as 44[deg] N. 
(Barlow 2014). Short-beaked common dolphins are not listed as 
endangered or threatened under the ESA, and the California/Oregon/
Washington stock is not considered a depleted or strategic stock under 
the MMPA.

Pacific White-Sided Dolphin

    Pacific white-sided dolphins are endemic to temperate waters of the 
North Pacific Ocean, and common both on the high seas and along the 
continental margins (Brownell et al. 1999). In the eastern North 
Pacific Ocean, including waters off Oregon, the Pacific white-sided 
dolphin is one of the most common cetacean species, occurring primarily 
in shelf and slope waters (Green et al. 1993; Barlow 2003, 2010). It is 
known to occur close to shore in certain regions, including seasonally 
off southern California (Brownell et al. 1999).
    Based on year-round aerial surveys off Oregon/Washington, the 
Pacific white-sided dolphin was the most abundant cetacean species 
(Green et al. 1992, 1993). Adams et al. (2014) also reported numerous 
offshore sightings off Oregon during summer, fall, and winter surveys 
in 2011 and 2012, including in the Southern Oregon survey area during 
September. Pacific white-sided dolphins are not listed as endangered or 
threatened under the ESA, and the California/Oregon/Washington stock is 
not considered a depleted or strategic stock under the MMPA.

Northern Right Whale Dolphin

    Northern right-whale dolphins are endemic to temperate waters of 
the North Pacific Ocean. Off the U.S. west coast, they have been seen 
primarily in shelf and slope waters, with seasonal movements into the 
Southern California Bight (Leatherwood and Walker 1979; Dohl et al. 
1980; 1983). Becker et al. (2014) predicted relatively high densities 
off southern Oregon, and moderate densities off northern Oregon and 
Washington. Barlow (2003, 2010) also found that the northern right 
whale dolphin was one of the most abundant marine mammal species off 
Oregon/Washington during 1996, 2001, 2005, and 2008 shipboard surveys. 
Several sightings were within and near the Astoria Fan and Southern 
Oregon survey areas during the summer and fall during surveys off 
California, Oregon and Washington (Forney 2007; Barlow 2010; Becker et 
al. 2012; Carretta et al. 2017). Northern right-whale dolphins are not 
listed as endangered or threatened under the ESA, and the California/
Oregon/Washington stock is not considered a depleted or strategic stock 
under the MMPA.

Risso's Dolphin

    Risso's dolphins are found in tropical to warm-temperate waters 
(Carretta et al., 2016). The species occurs from coastal to deep water 
but is most often found in depths greater than 3,000 m with the highest 
sighting rate in depths greater than 4,500 m (Baird 2016). It primarily 
occurs between 60[ordm]N and 60[ordm]S where surface water temperatures 
are at least 10[ordm]C (Kruse et al. 1999). The distribution and 
abundance of Risso's dolphin is highly variable from California to 
Washington, presumably in response to changing oceanographic conditions 
on both annual and seasonal time scales (Forney and Barlow 1998; 
Buchanan et al. 2001). The highest densities were predicted along the 
coasts of Washington, Oregon, and central and southern California 
(Becker et al. 2012). Off Oregon and Washington, Risso's dolphins are 
most abundant over continental slope and shelf waters during spring and 
summer, less so during fall, and rare during winter (Green et al. 1992, 
1993). Risso's dolphins were sighted off Oregon, including near the 
Astoria Fan and Southern Oregon survey areas, in June and October 2011 
(Adams et al. 2014). Risso's dolphins are not listed as endangered or 
threatened under the ESA, and the California/Oregon/Washington stock is 
not considered a depleted or strategic stock under the MMPA.

[[Page 39284]]

Cuvier's Beaked Whale

    Cuvier's beaked whale is the most widespread of the beaked whales 
occurring in almost all temperate, subtropical, and tropical waters and 
even some sub-polar and polar waters (MacLeod et al. 2006). It is found 
in deep water over and near the continental slope (Jefferson et al. 
2008). Cuvier's beaked whale abundance for waters off Oregon and 
Washington in 2014 was estimated at 432 (Barlow 2016). One Cuvier's 
beaked whale sighting was made west of the proposed Southern Oregon 
survey area during the 1991-2008 surveys (Carretta et al. 2017). One 
sighting of three individuals was recorded in June 2006 during surveys 
off Washington during August 2004 through September 2008, north of the 
Astoria Fan survey area (Oleson et al. 2009). Cuvier's beaked whales 
are not listed as endangered or threatened under the ESA, and the 
California/Oregon/Washington stock is not considered a depleted or 
strategic stock under the MMPA.

Baird's Beaked Whale

    Baird's beaked whales are distributed throughout deep waters and 
along the continental slopes of the North Pacific Ocean (Balcomb 1989, 
Macleod et al. 2006). It is sometimes seen close to shore where deep 
water approaches the coast, but its primary habitat is over or near the 
continental slope and oceanic seamounts (Jefferson et al. 2015). Along 
the U.S. west coast, Baird's beaked whales have been sighted primarily 
along the continental slope (Green et al. 1992; Becker et al. 2012; 
Carretta et al. 2016a) from late spring to early fall (Green et al. 
1992). During 1991-2008 surveys, several sightings were reported to the 
south and west of the Southern Oregon survey area, to the west of the 
Astoria Fan survey area, and within the eastern portion of the Astoria 
Fan survey area (Carretta et al. 2016a). Predicted density modeling 
showed higher densities in slope waters off northern Oregon, near the 
Astoria Fan survey area, compared with southern Oregon (Becker et al. 
2012). Baird's beaked whales are not listed as endangered or threatened 
under the ESA, and the California/Oregon/Washington stock is not 
considered a depleted or strategic stock under the MMPA.

Mesoplodont Beaked Whales

    Mesoplodont beaked whales are distributed throughout deep waters 
and along the continental slopes of the North Pacific Ocean. The six 
species known to occur in this region are: Blainville's beaked whale 
(M. densirostris), Perrin's beaked whale (M. perrini), Lesser beaked 
whale (M. peruvianus), Stejneger's beaked whale (M. stejnegeri), 
Gingko-toothed beaked whale (M. gingkodens), and Hubbs' beaked whale 
(M. carlhubbsi) (Mead 1989, Henshaw et al. 1997, Dalebout et al. 2002, 
MacLeod et al. 2006). Based on bycatch and stranding records in this 
region, it appears that Hubb's beaked whale is most commonly 
encountered (Carretta et al. 2008, Moore and Barlow 2013). Insufficient 
sighting records exist off the U.S. west coast to determine any 
possible spatial or seasonal patterns in the distribution of 
mesoplodont beaked whales. Until methods of distinguishing these six 
species at-sea are developed, the management unit must be defined to 
include all Mesoplodon stocks in this region. Although mesoplodont 
beaked whales have been sighted along the U.S. west coast on several 
line transect surveys utilizing both aerial and shipboard platforms, 
the rarity of sightings has historically precluded reliable population 
estimates. Mesoplodont beaked are not listed as endangered or 
threatened under the ESA, and the California, Oregon and Washington 
stock is not considered a depleted or strategic stock under the MMPA.

California Sea Lion

    The primary range of the California sea lion includes the coastal 
areas and offshore islands of the eastern North Pacific Ocean from 
British Columbia, Canada, to central Mexico, including the Gulf of 
California (Jefferson et al. 2015). However, its distribution is 
expanding (Jefferson et al. 2015), and its secondary range extends into 
the Gulf of Alaska where it is occasionally recorded (Maniscalco et al. 
2004) and southern Mexico (Gallo-Reynoso and Sol[oacute]rzano-Velasco 
1991). California sea lion breeding areas are on islands located in 
southern California, in western Baja California (Mexico), and the Gulf 
of California. During the breeding season, most California sea lions 
inhabit southern California and Mexico. In California and Baja 
California, births occur on land from mid-May to late June.
    California sea lions are coastal animals that often haul out on 
shore throughout the year. Off Oregon and Washington, peak numbers 
occur during the fall. During aerial surveys off the coasts of Oregon 
and Washington during 1989-1990, California sea lions were sighted at 
sea during the fall and winter, but no sightings were made during June-
August (Bonnell et al. 1992). Numbers off Oregon decrease during 
winter, as animals travel further north (Mate 1975 in Bonnell et al. 
1992). California sea lions are not listed as threatened or endangered 
under the ESA, and the U.S. stock is not considered a depleted or 
strategic stock under the MMPA.

Steller Sea Lion

    Steller sea lions range along the North Pacific Rim from northern 
Japan to California (Loughlin et al. 1984), with centers of abundance 
and distribution in the Gulf of Alaska and Aleutian Islands. They 
typically inhabit waters from the coast to the outer continental shelf 
and slope throughout their range and are not considered migratory, 
although foraging animals can travel long distances (Loughlin et al. 
2003; Raum-Suryan et al. 2002).
    During surveys off the coasts of Oregon and Washington, Bonnell et 
al. (1992) noted that 89 percent of sea lions occurred over the shelf 
at a mean distance of 21 km from the coast and near or in waters <200 m 
deep; the farthest sighting occurred ~40 km from shore, and the deepest 
sighting location was 1,611 m deep. Sightings were made along the 200 m 
depth contour within and near the proposed Astoria Fan and Southern 
Oregon survey sites throughout the year (Bonnell et al. 1992). The 
Eastern DPS of Steller sea lions is not listed as endangered or 
threatened under the ESA and the Eastern U.S. stock is not considered a 
depleted or strategic stock under the MMPA.

Harbor Seal

    Harbor seals inhabit coastal and estuarine waters off Baja 
California, north along the western coasts of the continental U.S., 
British Columbia, and Southeast Alaska, west through the Gulf of Alaska 
and Aleutian Islands, and in the Bering Sea north to Cape Newenham and 
the Pribilof Islands. They haul out on rocks, reefs, beaches, and 
drifting glacial ice and feed in marine, estuarine, and occasionally 
fresh waters. Harbor seals generally are non-migratory, with local 
movements associated with tides, weather, season, food availability, 
and reproduction (Scheffer and Slipp 1944; Fisher 1952; Bigg 1969, 
1981).
    Jeffries et al. (2000) documented several harbor seal rookeries and 
haulouts along the Washington coastline; it is the only pinniped 
species that breeds in Washington. During surveys off the Oregon and 
Washington coasts, 88 percent of at-sea harbor seals occurred over 
shelf waters <200 m deep, with a few sightings near the 2000 m contour, 
and only one sighting over deeper water (Bonnell et al. 1992). Most

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(68 percent) at-sea sightings were recorded in September and November 
(Bonnell et al. 1992). Harbor seals are not listed as endangered or 
threatened under the ESA and the Oregon/Washington coast stock is not 
considered a depleted or strategic stock under the MMPA.

Northern Elephant Seal

    Northern elephant seals gather at breeding areas, located primarily 
on offshore islands of Baja California and California, from 
approximately December to March before dispersing for feeding. Males 
feed near the eastern Aleutian Islands and in the Gulf of Alaska, while 
females feed at sea south of 45[deg] N. (Stewart and Huber, 1993; Le 
Boeuf et al., 1993). Although movement and genetic exchange continues 
between rookeries, most elephant seals return to their natal rookeries 
when they start breeding (Huber et al., 1991). The California breeding 
population is now demographically isolated from the Baja California 
population and is considered to be a separate stock. Only the 
California breeding population is expected to occur in the proposed 
survey area. Off Washington, most elephant seal sightings at sea were 
during June, July, and September; off Oregon, sightings were recorded 
from November through May (Bonnell et al. 1992). Several seals were 
seen off Oregon during summer, fall, and winter surveys in 2011 and 
2012, including one near the Southern Oregon survey area during October 
2011 (Adams et al. 2014). Northern elephant seals are not listed as 
threatened or endangered under the ESA and the California breeding 
population is not considered a depleted or strategic stock under the 
MMPA.

Northern Fur Seal

    Northern fur seals occur from southern California north to the 
Bering Sea and west to the Okhotsk Sea and Honshu Island, Japan. Two 
stocks of northern fur seals are recognized in U.S. waters: an eastern 
Pacific stock and a California stock (formerly referred to as the San 
Miguel Island stock). Only the California stock is expected to occur in 
the proposed survey area. Due to differing requirements during the 
annual reproductive season, adult males and females typically occur 
ashore at different, though overlapping, times. Adult males occur 
ashore and defend reproductive territories during a 3-month period from 
June through August while adult females are found ashore for as long as 
6 months (June-November). The northern fur seals spends ~90 percent of 
its time at sea, typically in areas of upwelling along the continental 
slopes and over seamounts (Gentry 1981). The remainder of its life is 
spent on or near rookery islands or haulouts.
    Bonnell et al. (1992) noted the presence of northern fur seals 
year-round off Oregon/Washington, with the greatest numbers (87 
percent) occurring in January-May. Northern fur seals were seen as far 
out from the coast as 185 km, and numbers increased with distance from 
land; they were 5-6 times more abundant in offshore waters than over 
the shelf or slope (Bonnell et al. 1992). The highest densities were 
seen in the Columbia River plume (~46[deg] N.) and in deep offshore 
waters (>2000 m) off central and southern Oregon (Bonnell et al. 1992). 
The waters off Washington are a known foraging area for adult females, 
and concentrations of fur seals were also reported to occur near Cape 
Blanco, Oregon, at ~42.8[deg] N. (Pelland et al. 2014). Northern fur 
seals are not listed as threatened or endangered under the ESA listed 
and the California stock is not considered a depleted or strategic 
stock under the MMPA.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

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

Description of Active Acoustic Sound Sources

    This section contains a brief technical background on sound, the 
characteristics of certain sound types, and on metrics used in this 
proposal inasmuch as the information is relevant to the specified 
activity and to a discussion of the potential effects of the specified 
activity on marine mammals found later in this document.
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz (Hz) or cycles per second. Wavelength is the 
distance between two peaks or corresponding points of a sound wave 
(length of one cycle). Higher frequency sounds have shorter wavelengths 
than lower frequency sounds, and typically attenuate (decrease) more 
rapidly, except in certain cases in shallower water. Amplitude is the 
height of the sound pressure wave or the ``loudness'' of a sound and is 
typically described using the relative unit of the decibel (dB). A 
sound pressure level (SPL) in dB is described as the ratio between a 
measured pressure and a reference pressure (for underwater sound, this 
is 1 microPascal ([mu]Pa)) and is a logarithmic unit that accounts for 
large variations in amplitude; therefore, a relatively small change in 
dB corresponds to large changes in sound pressure. The source level 
(SL) represents the SPL referenced at a distance of 1 m from the source 
(referenced to 1 [mu]Pa) while the received level is the SPL at the 
listener's position (referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they may be accounted for in the summation of 
pressure levels (Hastings and Popper, 2005). This measurement is often 
used in the context of discussing behavioral effects, in part because 
behavioral effects, which often result from auditory cues, may be 
better expressed through averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa\2\-s) 
represents the total energy contained within a pulse and considers both 
intensity and duration of exposure. Peak sound pressure (also referred 
to as zero-to-peak sound pressure or 0-p) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source and is represented in the same units as the rms sound pressure. 
Another common metric is peak-to-peak sound pressure (pk-pk), which is 
the algebraic difference between the peak positive and peak negative 
sound pressures. Peak-to-peak pressure is typically approximately 6 dB 
higher than peak pressure (Southall et al., 2007).
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as

[[Page 39286]]

the sound wave travels. Underwater sound waves radiate in a manner 
similar to ripples on the surface of a pond and may be either directed 
in a beam or beams or may radiate in all directions (omnidirectional 
sources), as is the case for pulses produced by the airgun arrays 
considered here. The compressions and decompressions associated with 
sound waves are detected as changes in pressure by aquatic life and 
man-made sound receptors such as hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound. Ambient 
sound is defined as environmental background sound levels lacking a 
single source or point (Richardson et al., 1995), and the sound level 
of a region is defined by the total acoustical energy being generated 
by known and unknown sources. These sources may include physical (e.g., 
wind and waves, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic (e.g., vessels, dredging, construction) sound. A number 
of sources contribute to ambient sound, including the following 
(Richardson et al., 1995):
     Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient sound for frequencies between 200 Hz and 50 
kilohertz (kHz) (Mitson, 1995). In general, ambient sound levels tend 
to increase with increasing wind speed and wave height. Surf sound 
becomes important near shore, with measurements collected at a distance 
of 8.5 km from shore showing an increase of 10 dB in the 100 to 700 Hz 
band during heavy surf conditions.
     Precipitation: Sound from rain and hail impacting the 
water surface can become an important component of total sound at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times.
     Biological: Marine mammals can contribute significantly to 
ambient sound levels, as can some fish and snapping shrimp. The 
frequency band for biological contributions is from approximately 12 Hz 
to over 100 kHz.
     Anthropogenic: Sources of ambient sound related to human 
activity include transportation (surface vessels), dredging and 
construction, oil and gas drilling and production, seismic surveys, 
sonar, explosions, and ocean acoustic studies. Vessel noise typically 
dominates the total ambient sound for frequencies between 20 and 300 
Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz 
and, if higher frequency sound levels are created, they attenuate 
rapidly. Sound from identifiable anthropogenic sources other than the 
activity of interest (e.g., a passing vessel) is sometimes termed 
background sound, as opposed to ambient sound.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
human activity) but also on the ability of sound to propagate through 
the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al., 1995). The result is that, 
depending on the source type and its intensity, sound from a given 
activity may be a negligible addition to the local environment or could 
form a distinctive signal that may affect marine mammals. Details of 
source types are described in the following text.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al. (2007) for an in-depth discussion of these concepts.
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or non-continuous (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems (such as 
those used by the U.S. Navy). The duration of such sounds, as received 
at a distance, can be greatly extended in a highly reverberant 
environment.
    Airgun arrays produce pulsed signals with energy in a frequency 
range from about 10-2,000 Hz, with most energy radiated at frequencies 
below 200 Hz. The amplitude of the acoustic wave emitted from the 
source is equal in all directions (i.e., omnidirectional), but airgun 
arrays do possess some directionality due to different phase delays 
between guns in different directions. Airgun arrays are typically tuned 
to maximize functionality for data acquisition purposes, meaning that 
sound transmitted in horizontal directions and at higher frequencies is 
minimized to the extent possible.
    As described above, a MBES and a SBP would also be operated from 
the Revelle continuously throughout the survey, but not during transits 
to and from the project area. Due to the lower source level of the SBP 
relative to the Revelle's airgun array, the sounds from the SBP are 
expected to be effectively subsumed by the sounds from the airgun 
array. Thus, any marine mammal that was exposed to sounds from the SBP 
would already have been exposed to sounds from the airgun array, which 
are expected to propagate further in the water. As such, the SBP is not 
expected to result in the take of any marine mammal that has not 
already been taken by the sounds from the airgun array, and therefore 
we do not consider noise from the SBP further in this analysis. Each 
ping emitted by the MBES consists of four successive fan-shaped 
transmissions, each ensonifying a sector that extends 1[deg] fore-aft. 
Given the movement and speed of the vessel, the intermittent and narrow 
downward-directed nature of the sounds emitted by the MBES would result 
in no more than one or two brief ping exposures of any individual 
marine mammal, if any exposure were to occur. Thus, we conclude that 
the likelihood of marine mammal take resulting from MBES exposure is 
discountable and therefore

[[Page 39287]]

we do not consider noise from the MBES further in this analysis

Acoustic Effects

    Here, we first provide background information on marine mammal 
hearing before discussing the potential effects of the use of active 
acoustic sources on marine mammals.
    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 (2016) described generalized hearing ranges for 
these marine mammal hearing groups. Generalized hearing ranges were 
chosen based on the approximately 65 dB threshold from the normalized 
composite audiograms, with the exception for lower limits for low-
frequency cetaceans where the lower bound was deemed to be biologically 
implausible and the lower bound from Southall et al. (2007) retained. 
The functional groups and the associated frequencies are indicated 
below (note that these frequency ranges correspond to the range for the 
composite group, with the entire range not necessarily reflecting the 
capabilities of every species within that group):
     Low-frequency cetaceans (mysticetes): Generalized hearing 
is estimated to occur between approximately 7 Hz and 35 kHz, with best 
hearing estimated to be from 100 Hz to 8 kHz;
     Mid-frequency cetaceans (larger toothed whales, beaked 
whales, and most delphinids): Generalized hearing is estimated to occur 
between approximately 150 Hz and 160 kHz, with best hearing from 10 to 
less than 100 kHz;
     High-frequency cetaceans (porpoises, river dolphins, and 
members of the genera Kogia and Cephalorhynchus; including two members 
of the genus Lagenorhynchus, on the basis of recent echolocation data 
and genetic data): Generalized hearing is estimated to occur between 
approximately 275 Hz and 160 kHz.
     Pinnipeds in water; Phocidae (true seals): Generalized 
hearing is estimated to occur between approximately 50 Hz to 86 kHz, 
with best hearing between 1-50 kHz;
     Pinnipeds in water; Otariidae (eared seals): Generalized 
hearing is estimated to occur between 60 Hz and 39 kHz, with best 
hearing between 2-48 kHz.
    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).

 Table 3--Marine Functional Mammal Hearing Groups and Their Generalized
                             Hearing Ranges
------------------------------------------------------------------------
               Hearing group                  Generalized hearing range*
------------------------------------------------------------------------
Low frequency (LF) cetaceans (baleen         7Hz to 35 kHz.
 whales).
Mid-frequency (MF) cetaceans (dolphins,      150 Hz to 160 kHz.
 toothed whales, beaked whales, bottlenose
 whales).
High-frequency (HF) cetaceans (true          275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 cephalorhynchid, Lagenorhynchus cruciger
 and L. australis).
Phocid pinnipeds (PW) (underwater) (true     50 Hz to 86 kHz.
 seals).
Otariid pinnipeds (OW) (underwater) (sea     60 Hz to 39 kHz.
 lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al., 2007) and PW pinniped (approximation).

    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2016) for a review of available information. 
Twenty four marine mammal species (all cetaceans) have the reasonable 
potential to co-occur with the proposed survey activities. Please refer 
to Table 2. Of the cetacean species that may be present, 6 are 
classified as low-frequency cetaceans (i.e., all mysticete species), 16 
are classified as mid-frequency cetaceans (i.e., all delphinid and 
ziphiid species and the sperm whale), and 2 are classified as high-
frequency cetaceans (i.e., Kogia spp.).
    Potential Effects of Underwater Sound--Please refer to the 
information given previously (``Description of Active Acoustic 
Sources'') regarding sound, characteristics of sound types, and metrics 
used in this document. Note that, in the following discussion, we refer 
in many cases to a recent review article concerning studies of noise-
induced hearing loss conducted from 1996-2015 (i.e., Finneran, 2015). 
For study-specific citations, please see that work. Anthropogenic 
sounds cover a broad range of frequencies and sound levels and can have 
a range of highly variable impacts on marine life, from none or minor 
to potentially severe responses, depending on received levels, duration 
of exposure, behavioral context, and various other factors. The 
potential effects of underwater sound from active acoustic sources can 
potentially result in one or more of the following: Temporary or 
permanent hearing impairment, non-auditory physical or physiological 
effects, behavioral disturbance, stress, and masking (Richardson et 
al., 1995; Gordon et al., 2004; Nowacek et al., 2007; Southall et al., 
2007; G[ouml]tz et al., 2009). The degree of effect is intrinsically 
related to the signal characteristics, received level, distance from 
the source, and duration of the sound exposure. In general, sudden, 
high level sounds can cause hearing loss, as can longer exposures to 
lower level sounds. Temporary or permanent loss of hearing will occur 
almost exclusively for noise within an animal's hearing range. We first 
describe specific manifestations of acoustic effects before providing 
discussion specific to the use of airguns.
    Richardson et al. (1995) described zones of increasing intensity of 
effect that might be expected to occur, in relation to distance from a 
source and assuming that the signal is within an animal's hearing 
range. First is the area

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within which the acoustic signal would be audible (potentially 
perceived) to the animal, but not strong enough to elicit any overt 
behavioral or physiological response. The next zone corresponds with 
the area where the signal is audible to the animal and of sufficient 
intensity to elicit behavioral or physiological responsiveness. Third 
is a zone within which, for signals of high intensity, the received 
level is sufficient to potentially cause discomfort or tissue damage to 
auditory or other systems. Overlaying these zones to a certain extent 
is the area within which masking (i.e., when a sound interferes with or 
masks the ability of an animal to detect a signal of interest that is 
above the absolute hearing threshold) may occur; the masking zone may 
be highly variable in size.
    We describe the more severe effects certain non-auditory physical 
or physiological effects only briefly as we do not expect that use of 
airgun arrays are reasonably likely to result in such effects (see 
below for further discussion). Potential effects from impulsive sound 
sources can range in severity from effects such as behavioral 
disturbance or tactile perception to physical discomfort, slight injury 
of the internal organs and the auditory system, or mortality (Yelverton 
et al., 1973). Non-auditory physiological effects or injuries that 
theoretically might occur in marine mammals exposed to high level 
underwater sound or as a secondary effect of extreme behavioral 
reactions (e.g., change in dive profile as a result of an avoidance 
reaction) caused by exposure to sound include neurological effects, 
bubble formation, resonance effects, and other types of organ or tissue 
damage (Cox et al., 2006; Southall et al., 2007; Zimmer and Tyack, 
2007; Tal et al., 2015). The survey activities considered here do not 
involve the use of devices such as explosives or mid-frequency tactical 
sonar that are associated with these types of effects.
    1. Threshold Shift--Marine mammals exposed to high-intensity sound, 
or to lower-intensity sound for prolonged periods, can experience 
hearing threshold shift (TS), which is the loss of hearing sensitivity 
at certain frequency ranges (Finneran, 2015). TS can be permanent 
(PTS), in which case the loss of hearing sensitivity is not fully 
recoverable, or temporary (TTS), in which case the animal's hearing 
threshold would recover over time (Southall et al., 2007). Repeated 
sound exposure that leads to TTS could cause PTS. In severe cases of 
PTS, there can be total or partial deafness, while in most cases the 
animal has an impaired ability to hear sounds in specific frequency 
ranges (Kryter, 1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). In addition, other 
investigators have suggested that TTS is within the normal bounds of 
physiological variability and tolerance and does not represent physical 
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to 
constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al. 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulse sounds (such as airgun pulses as 
received close to the source) are at least 6 dB higher than the TTS 
threshold on a peak-pressure basis and PTS cumulative sound exposure 
level thresholds are 15 to 20 dB higher than TTS cumulative sound 
exposure level thresholds (Southall et al., 2007). Given the higher 
level of sound or longer exposure duration necessary to cause PTS as 
compared with TTS, it is considerably less likely that PTS could occur.
    For mid-frequency cetaceans in particular, potential protective 
mechanisms may help limit onset of TTS or prevent onset of PTS. Such 
mechanisms include dampening of hearing, auditory adaptation, or 
behavioral amelioration (e.g., Nachtigall and Supin, 2013; Miller et 
al., 2012; Finneran et al., 2015; Popov et al., 2016).
    TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. Few data 
on sound levels and durations necessary to elicit mild TTS have been 
obtained for marine mammals.
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS, and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to 
serious. For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that occurs during a time where ambient noise is lower and there 
are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts.
    Finneran et al. (2015) measured hearing thresholds in three captive 
bottlenose dolphins before and after exposure to ten pulses produced by 
a seismic airgun in order to study TTS induced after exposure to 
multiple pulses. Exposures began at relatively low levels and gradually 
increased over a period of several months, with the highest exposures 
at peak SPLs from 196 to 210 dB and cumulative (unweighted) SELs from 
193-195 dB. No substantial TTS was observed. In addition, behavioral 
reactions were observed that indicated that animals can learn behaviors 
that effectively mitigate noise exposures (although exposure patterns 
must be learned, which is less likely in wild animals than for the 
captive animals considered in this study). The authors note that the 
failure to induce more significant auditory effects likely due to the 
intermittent nature of exposure, the relatively low peak pressure 
produced by the acoustic source, and the low-frequency energy in airgun 
pulses as compared with the frequency range of best sensitivity for 
dolphins and other mid-frequency cetaceans.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin, beluga whale, harbor porpoise, and Yangtze finless 
porpoise) exposed to a limited number of sound sources (i.e., mostly 
tones and octave-band noise) in laboratory settings (Finneran, 2015). 
In general, harbor porpoises have a lower TTS onset than other measured 
cetacean species (Finneran, 2015). Additionally, the existing marine 
mammal TTS data come from a limited number of individuals within these 
species. There are no data available on noise-induced hearing loss for 
mysticetes.
    Critical questions remain regarding the rate of TTS growth and 
recovery after exposure to intermittent noise and

[[Page 39289]]

the effects of single and multiple pulses. Data at present are also 
insufficient to construct generalized models for recovery and determine 
the time necessary to treat subsequent exposures as independent events. 
More information is needed on the relationship between auditory evoked 
potential and behavioral measures of TTS for various stimuli. For 
summaries of data on TTS in marine mammals or for further discussion of 
TTS onset thresholds, please see Southall et al. (2007), Finneran and 
Jenkins (2012), Finneran (2015), and NMFS (2016).
    2. Behavioral Effects--Behavioral disturbance may include a variety 
of effects, including subtle changes in behavior (e.g., minor or brief 
avoidance of an area or changes in vocalizations), more conspicuous 
changes in similar behavioral activities, and more sustained and/or 
potentially severe reactions, such as displacement from or abandonment 
of high-quality habitat. Behavioral responses to sound are highly 
variable and context-specific and any reactions depend on numerous 
intrinsic and extrinsic factors (e.g., species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day), as well as the interplay between factors (e.g., 
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007; 
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not 
only among individuals but also within an individual, depending on 
previous experience with a sound source, context, and numerous other 
factors (Ellison et al., 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). 
Please see Appendices B-C of Southall et al. (2007) for a review of 
studies involving marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. As noted, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with 
captive marine mammals have showed pronounced behavioral reactions, 
including avoidance of loud sound sources (Ridgway et al., 1997). 
Observed responses of wild marine mammals to loud pulsed sound sources 
(typically seismic airguns or acoustic harassment devices) have been 
varied but often consist of avoidance behavior or other behavioral 
changes suggesting discomfort (Morton and Symonds, 2002; see also 
Richardson et al., 1995; Nowacek et al., 2007). However, many 
delphinids approach acoustic source vessels with no apparent discomfort 
or obvious behavioral change (e.g., Barkaszi et al., 2012).
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely, and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark 2000; Ng and Leung 2003; Nowacek et al. 2004; Goldbogen et 
al. 2013). Variations in dive behavior may reflect interruptions in 
biologically significant activities (e.g., foraging) or they may be of 
little biological significance. The impact of an alteration to dive 
behavior resulting from an acoustic exposure depends on what the animal 
is doing at the time of the exposure and the type and magnitude of the 
response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al. 
2001; Nowacek et al. 2004; Madsen et al. 2006; Yazvenko et al. 2007). A 
determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Visual tracking, passive acoustic monitoring, and movement 
recording tags were used to quantify sperm whale behavior prior to, 
during, and following exposure to airgun arrays at received levels in 
the range 140-160 dB at distances of 7-13 km, following a phase-in of 
sound intensity and full array exposures at 1-13 km (Madsen et al., 
2006; Miller et al., 2009). Sperm whales did not exhibit horizontal 
avoidance behavior at the surface. However, foraging behavior may have 
been affected. The sperm whales exhibited 19 percent less vocal (buzz) 
rate during full exposure relative to post exposure, and the whale that 
was approached most closely had an extended resting period and did not 
resume foraging until the airguns had ceased firing. The remaining 
whales continued to execute foraging dives throughout exposure; 
however, swimming movements during foraging dives were six percent 
lower during exposure than control periods (Miller et al., 2009). These 
data raise concerns that seismic surveys may impact foraging behavior 
in sperm whales, although more data are required to understand whether 
the differences were due to exposure or natural variation in sperm 
whale behavior (Miller et al., 2009).
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that

[[Page 39290]]

respiration rates may either be unaffected or could increase, depending 
on the species and signal characteristics, again highlighting the 
importance in understanding species differences in the tolerance of 
underwater noise when determining the potential for impacts resulting 
from anthropogenic sound exposure (e.g., Kastelein et al., 2001, 2005, 
2006; Gailey et al., 2007; Gailey et al., 2016).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al., 
2000; Fristrup et al., 2003; Foote et al., 2004), while right whales 
have been observed to shift the frequency content of their calls upward 
while reducing the rate of calling in areas of increased anthropogenic 
noise (Parks et al., 2007). In some cases, animals may cease sound 
production during production of aversive signals (Bowles et al., 1994).
    Cerchio et al. (2014) used passive acoustic monitoring to document 
the presence of singing humpback whales off the coast of northern 
Angola and to opportunistically test for the effect of seismic survey 
activity on the number of singing whales. Two recording units were 
deployed between March and December 2008 in the offshore environment; 
numbers of singers were counted every hour. Generalized Additive Mixed 
Models were used to assess the effect of survey day (seasonality), hour 
(diel variation), moon phase, and received levels of noise (measured 
from a single pulse during each ten minute sampled period) on singer 
number. The number of singers significantly decreased with increasing 
received level of noise, suggesting that humpback whale breeding 
activity was disrupted to some extent by the survey activity.
    Castellote et al. (2012) reported acoustic and behavioral changes 
by fin whales in response to shipping and airgun noise. Acoustic 
features of fin whale song notes recorded in the Mediterranean Sea and 
northeast Atlantic Ocean were compared for areas with different 
shipping noise levels and traffic intensities and during a seismic 
airgun survey. During the first 72 hours of the survey, a steady 
decrease in song received levels and bearings to singers indicated that 
whales moved away from the acoustic source and out of the study area. 
This displacement persisted for a time period well beyond the 10-day 
duration of seismic airgun activity, providing evidence that fin whales 
may avoid an area for an extended period in the presence of increased 
noise. The authors hypothesize that fin whale acoustic communication is 
modified to compensate for increased background noise and that a 
sensitization process may play a role in the observed temporary 
displacement.
    Seismic pulses at average received levels of 131 dB re 1 
[micro]Pa\2\-s caused blue whales to increase call production (Di Iorio 
and Clark, 2010). In contrast, McDonald et al. (1995) tracked a blue 
whale with seafloor seismometers and reported that it stopped 
vocalizing and changed its travel direction at a range of 10 km from 
the acoustic source vessel (estimated received level 143 dB pk-pk). 
Blackwell et al. (2013) found that bowhead whale call rates dropped 
significantly at onset of airgun use at sites with a median distance of 
41-45 km from the survey. Blackwell et al. (2015) expanded this 
analysis to show that whales actually increased calling rates as soon 
as airgun signals were detectable before ultimately decreasing calling 
rates at higher received levels (i.e., 10-minute SELcum of 
~127 dB). Overall, these results suggest that bowhead whales may adjust 
their vocal output in an effort to compensate for noise before ceasing 
vocalization effort and ultimately deflecting from the acoustic source 
(Blackwell et al., 2013, 2015). These studies demonstrate that even low 
levels of noise received far from the source can induce changes in 
vocalization and/or behavior for mysticetes.
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Humpback whales showed avoidance behavior in the presence of an 
active seismic array during observational studies and controlled 
exposure experiments in western Australia (McCauley et al., 2000). 
Avoidance may be short-term, with animals returning to the area once 
the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; Stone et 
al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). Longer-term 
displacement is possible, however, which may lead to changes in 
abundance or distribution patterns of the affected species in the 
affected region if habituation to the presence of the sound does not 
occur (e.g., Bejder et al., 2006; Teilmann et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, marine mammal strandings 
(Evans and England, 2001). However, it should be noted that response to 
a perceived predator does not necessarily invoke flight (Ford and 
Reeves, 2008), and whether individuals are solitary or in groups may 
influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil 1997; Fritz et al. 2002; Purser and Radford 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch 1992; Daan et al. 1996; Bradshaw et al. 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a five-day period did not cause any 
sleep deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent

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days (Southall et al., 2007). Consequently, a behavioral response 
lasting less than one day and not recurring on subsequent days is not 
considered particularly severe unless it could directly affect 
reproduction or survival (Southall et al., 2007). Note that there is a 
difference between multi-day substantive behavioral reactions and 
multi-day anthropogenic activities. For example, just because an 
activity lasts for multiple days does not necessarily mean that 
individual animals are either exposed to activity-related stressors for 
multiple days or, further, exposed in a manner resulting in sustained 
multi-day substantive behavioral responses.
    Stone (2015) reported data from at-sea observations during 1,196 
seismic surveys from 1994 to 2010. When large arrays of airguns 
(considered to be 500 in\3\ or more) were firing, lateral displacement, 
more localized avoidance, or other changes in behavior were evident for 
most odontocetes. However, significant responses to large arrays were 
found only for the minke whale and fin whale. Behavioral responses 
observed included changes in swimming or surfacing behavior, with 
indications that cetaceans remained near the water surface at these 
times. Cetaceans were recorded as feeding less often when large arrays 
were active. Behavioral observations of gray whales during a seismic 
survey monitored whale movements and respirations pre-, during and 
post-seismic survey (Gailey et al., 2016). Behavioral state and water 
depth were the best `natural' predictors of whale movements and 
respiration and, after considering natural variation, none of the 
response variables were significantly associated with seismic survey or 
vessel sounds.
    3. Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg 1987; Blecha 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al. 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficiently to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    4. Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al., 1995; Erbe et al., 
2016). Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher intensity, and may occur whether the sound is natural (e.g., 
snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g., 
shipping, sonar, seismic exploration) in origin. The ability of a noise 
source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is man-made, it may be considered harassment 
when disrupting or altering critical behaviors. It is important to 
distinguish TTS and PTS, which persist after the sound exposure, from 
masking, which occurs during the sound exposure. Because masking 
(without resulting in TS) is not associated with abnormal physiological 
function, it is not considered a physiological effect, but rather a 
potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al. 2000; 
Foote et al. 2004; Parks et al. 2007; Di Iorio and Clark 2009; Holt et 
al. 2009). Masking can be reduced in situations where the signal and 
noise come from different directions (Richardson et al. 1995), through 
amplitude modulation of the signal, or through other compensatory 
behaviors (Houser and Moore 2014). Masking can be tested directly in 
captive species (e.g., Erbe 2008), but in wild

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populations it must be either modeled or inferred from evidence of 
masking compensation. There are few studies addressing real-world 
masking sounds likely to be experienced by marine mammals in the wild 
(e.g., Branstetter et al. 2013).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency 
ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.

Ship Strike

    Vessel collisions with marine mammals, or ship strikes, can result 
in death or serious injury of the animal. Wounds resulting from ship 
strike may include massive trauma, hemorrhaging, broken bones, or 
propeller lacerations (Knowlton and Kraus 2001). An animal at the 
surface may be struck directly by a vessel, a surfacing animal may hit 
the bottom of a vessel, or an animal just below the surface may be cut 
by a vessel's propeller. Superficial strikes may not kill or result in 
the death of the animal. These interactions are typically associated 
with large whales (e.g., fin whales), which are occasionally found 
draped across the bulbous bow of large commercial ships upon arrival in 
port. Although smaller cetaceans are more maneuverable in relation to 
large vessels than are large whales, they may also be susceptible to 
strike. The severity of injuries typically depends on the size and 
speed of the vessel, with the probability of death or serious injury 
increasing as vessel speed increases (Knowlton and Kraus 2001; Laist et 
al. 2001; Vanderlaan and Taggart 2007; Conn and Silber 2013). Impact 
forces increase with speed, as does the probability of a strike at a 
given distance (Silber et al. 2010; Gende et al. 2011).
    Pace and Silber (2005) also found that the probability of death or 
serious injury increased rapidly with increasing vessel speed. 
Specifically, the predicted probability of serious injury or death 
increased from 45 to 75 percent as vessel speed increased from 10 to 14 
kn, and exceeded 90 percent at 17 kn. Higher speeds during collisions 
result in greater force of impact, but higher speeds also appear to 
increase the chance of severe injuries or death through increased 
likelihood of collision by pulling whales toward the vessel (Clyne, 
1999; Knowlton et al. 1995). In a separate study, Vanderlaan and 
Taggart (2007) analyzed the probability of lethal mortality of large 
whales at a given speed, showing that the greatest rate of change in 
the probability of a lethal injury to a large whale as a function of 
vessel speed occurs between 8.6 and 15 kt. The chances of a lethal 
injury decline from approximately 80 percent at 15 kt to approximately 
20 percent at 8.6 kt. At speeds below 11.8 kt, the chances of lethal 
injury drop below 50 percent, while the probability asymptotically 
increases toward one hundred percent above 15 kt.
    The Revelle travels at a speed of ~9.3 km/hour (5 kt) while towing 
seismic survey gear (LGL 2017). At this speed, both the possibility of 
striking a marine mammal and the possibility of a strike resulting in 
serious injury or mortality are discountable. At average transit speed, 
the probability of serious injury or mortality resulting from a strike 
is less than 50 percent. However, the likelihood of a strike actually 
happening is again discountable. Ship strikes, as analyzed in the 
studies cited above, generally involve commercial shipping, which is 
much more common in both space and time than is geophysical survey 
activity. Jensen and Silber (2004) summarized ship strikes of large 
whales worldwide from 1975-2003 and found that most collisions occurred 
in the open ocean and involved large vessels (e.g., commercial 
shipping). Commercial fishing vessels were responsible for three 
percent of recorded collisions, while no such incidents were reported 
for geophysical survey vessels during that time period.
    It is possible for ship strikes to occur while traveling at slow 
speeds. For example, a hydrographic survey vessel traveling at low 
speed (5.5 kt) while conducting mapping surveys off the central 
California coast struck and killed a blue whale in 2009. The State of 
California determined that the whale had suddenly and unexpectedly 
surfaced beneath the hull, with the result that the propeller severed 
the whale's vertebrae, and that this was an unavoidable event. This 
strike represents the only such incident in approximately 540,000 hours 
of similar coastal mapping activity (p = 1.9 x 10-\6\; 95% 
CI = 0-5.5 x 10-\6\; NMFS, 2013b). In addition, a research 
vessel reported a fatal strike in 2011 of a dolphin in the Atlantic, 
demonstrating that it is possible for strikes involving smaller 
cetaceans to occur. In that case, the incident report indicated that an 
animal apparently was struck by the vessel's propeller as it was 
intentionally swimming near the vessel. While indicative of the type of 
unusual events that cannot be ruled out, neither of these instances 
represents a circumstance that would be considered reasonably 
foreseeable or that would be considered preventable.
    Although the likelihood of the vessel striking a marine mammal is 
low, we require a robust ship strike avoidance protocol (see ``Proposed 
Mitigation''), which we believe eliminates any foreseeable risk of ship 
strike. We anticipate that vessel collisions involving a seismic data 
acquisition vessel towing gear, while not impossible, represent 
unlikely, unpredictable events for which there are no preventive 
measures. Given the required mitigation measures, the relatively slow 
speed of the vessel towing gear, the presence of bridge crew watching 
for obstacles at all times (including marine mammals), the presence of 
marine mammal observers, and the short duration of the survey (5.5 
days), we believe that the possibility of ship strike is discountable 
and, further, that were a strike of a large whale to occur, it would be 
unlikely to result in serious injury or mortality. No incidental take 
resulting from ship strike is anticipated, and this potential effect of 
the specified activity will not be discussed further in the following 
analysis.
    Stranding--When a living or dead marine mammal swims or floats onto 
shore and becomes ``beached'' or incapable of returning to sea, the 
event is a ``stranding'' (Geraci et al. 1999; Perrin and Geraci 2002; 
Geraci and Lounsbury 2005; NMFS, 2007). The legal definition for a 
stranding under the MMPA is (A) a marine mammal is dead and is (i) on a 
beach or shore of the United States; or (ii) in waters under the 
jurisdiction of the United States (including any navigable waters); or 
(B) a marine mammal is alive and is (i) on a beach or shore of the 
United States and is unable to return to the water; (ii) on a beach or 
shore of the United States and, although able to return to the water, 
is in need of apparent medical attention; or (iii) in the waters under 
the jurisdiction of the United States (including any navigable waters), 
but is unable to return to its natural habitat under its own power or 
without assistance.
    Marine mammals strand for a variety of reasons, such as infectious 
agents, biotoxicosis, starvation, fishery interaction, ship strike, 
unusual oceanographic or weather events, sound

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exposure, or combinations of these stressors sustained concurrently or 
in series. However, the cause or causes of most strandings are unknown 
(Geraci et al. 1976; Eaton, 1979; Odell et al. 1980; Best 1982). 
Numerous studies suggest that the physiology, behavior, habitat 
relationships, age, or condition of cetaceans may cause them to strand 
or might pre-dispose them to strand when exposed to another phenomenon. 
These suggestions are consistent with the conclusions of numerous other 
studies that have demonstrated that combinations of dissimilar 
stressors commonly combine to kill an animal or dramatically reduce its 
fitness, even though one exposure without the other does not produce 
the same result (Chroussos 2000; Creel 2005; DeVries et al. 2003; Fair 
and Becker 2000; Foley et al. 2001; Moberg, 2000; Relyea 2005; Romero 
2004; Sih et al. 2004).
    Use of military tactical sonar has been implicated in a majority of 
investigated stranding events, although one stranding event was 
associated with the use of seismic airguns. This event occurred in the 
Gulf of California, coincident with seismic reflection profiling by the 
R/V Maurice Ewing operated by Lamont-Doherty Earth Observatory (LDEO) 
of Columbia University and involved two Cuvier's beaked whales 
(Hildebrand 2004). The vessel had been firing an array of 20 airguns 
with a total volume of 8,500 in\3\ (Hildebrand 2004; Taylor et al. 
2004). Most known stranding events have involved beaked whales, though 
a small number have involved deep-diving delphinids or sperm whales 
(e.g., Mazzariol et al. 2010; Southall et al. 2013). In general, long 
duration (~1 second) and high-intensity sounds (>235 dB SPL) have been 
implicated in stranding events (Hildebrand 2004). With regard to beaked 
whales, mid-frequency sound is typically implicated (when causation can 
be determined) (Hildebrand 2004). Although seismic airguns create 
predominantly low-frequency energy, the signal does include a mid-
frequency component. We have considered the potential for the proposed 
survey to result in marine mammal stranding and have concluded that, 
based on the best available information, stranding is not expected to 
occur.
    Other Potential Impacts--Here, we briefly address the potential 
risks due to entanglement and contaminant spills. We are not aware of 
any records of marine mammal entanglement in towed arrays such as those 
considered here. The discharge of trash and debris is prohibited (33 
CFR 151.51-77) unless it is passed through a machine that breaks up 
solids such that they can pass through a 25-mm mesh screen. All other 
trash and debris must be returned to shore for proper disposal with 
municipal and solid waste. Some personal items may be accidentally lost 
overboard. However, U.S. Coast Guard and Environmental Protection Act 
regulations require operators to become proactive in avoiding 
accidental loss of solid waste items by developing waste management 
plans, posting informational placards, manifesting trash sent to shore, 
and using special precautions such as covering outside trash bins to 
prevent accidental loss of solid waste. There are no meaningful 
entanglement risks posed by the described activity, and entanglement 
risks are not discussed further in this document.
    Marine mammals could be affected by accidentally spilled diesel 
fuel from a vessel associated with proposed survey activities. 
Quantities of diesel fuel on the sea surface may affect marine mammals 
through various pathways: surface contact of the fuel with skin and 
other mucous membranes, inhalation of concentrated petroleum vapors, or 
ingestion of the fuel (direct ingestion or by the ingestion of oiled 
prey) (e.g., Geraci and St. Aubin, 1980, 1985, 1990). However, the 
likelihood of a fuel spill during any particular geophysical survey is 
considered to be remote, and the potential for impacts to marine 
mammals would depend greatly on the size and location of a spill and 
meteorological conditions at the time of the spill. Spilled fuel would 
rapidly spread to a layer of varying thickness and break up into narrow 
bands or windrows parallel to the wind direction. The rate at which the 
fuel spreads would be determined by the prevailing conditions such as 
temperature, water currents, tidal streams, and wind speeds. Lighter, 
volatile components of the fuel would evaporate to the atmosphere 
almost completely in a few days. Evaporation rate may increase as the 
fuel spreads because of the increased surface area of the slick. 
Rougher seas, high wind speeds, and high temperatures also tend to 
increase the rate of evaporation and the proportion of fuel lost by 
this process (Scholz et al., 1999). We do not anticipate potentially 
meaningful effects to marine mammals as a result of any contaminant 
spill resulting from the proposed survey activities, and contaminant 
spills are not discussed further in this document.

Anticipated Effects on Marine Mammal Habitat

    Effects to Prey--Marine mammal prey varies by species, season, and 
location and, for some, is not well documented. Fish react to sounds 
which are especially strong and/or intermittent low-frequency sounds. 
Short duration, sharp sounds can cause overt or subtle changes in fish 
behavior and local distribution. Hastings and Popper (2005) identified 
several studies that suggest fish may relocate to avoid certain areas 
of sound energy. Additional studies have documented effects of pulsed 
sound on fish, although several are based on studies in support of 
construction projects (e.g., Scholik and Yan 2001, 2002; Popper and 
Hastings 2009). Sound pulses at received levels of 160 dB may cause 
subtle changes in fish behavior. SPLs of 180 dB may cause noticeable 
changes in behavior (Pearson et al. 1992; Skalski et al. 1992). SPLs of 
sufficient strength have been known to cause injury to fish and fish 
mortality. The most likely impact to fish from survey activities at the 
project area would be temporary avoidance of the area. The duration of 
fish avoidance of a given area after survey effort stops is unknown, 
but a rapid return to normal recruitment, distribution and behavior is 
anticipated.
    Information on seismic airgun impacts to zooplankton, which 
represent an important prey type for mysticetes, is limited. However, 
McCauley et al. (2017) reported that experimental exposure to a pulse 
from a 150 in\3\ airgun decreased zooplankton abundance when compared 
with controls, as measured by sonar and net tows, and caused a two- to 
threefold increase in dead adult and larval zooplankton. Although no 
adult krill were present, the study found that all larval krill were 
killed after air gun passage. Impacts were observed out to the maximum 
1.2 km range sampled.
    In general, impacts to marine mammal prey are expected to be 
limited due to the relatively small temporal and spatial overlap 
between the proposed survey and any areas used by marine mammal prey 
species. The proposed survey would occur over a relatively short time 
period (5.5 days) and would occur over a very small area relative to 
the area available as marine mammal habitat in the northeast Pacific 
Ocean. We do not have any information to suggest the proposed survey 
area represents a significant feeding area for any marine mammal, and 
we believe any impacts to marine mammals due to adverse affects to 
their prey would be insignificant due to the limited spatial and 
temporal

[[Page 39294]]

impact of the proposed survey. However, adverse impacts may occur to a 
few species of fish and to zooplankton.
    Acoustic Habitat--Acoustic habitat is the soundscape--which 
encompasses all of the sound present in a particular location and time, 
as a whole--when considered from the perspective of the animals 
experiencing it. Animals produce sound for, or listen for sounds 
produced by, conspecifics (communication during feeding, mating, and 
other social activities), other animals (finding prey or avoiding 
predators), and the physical environment (finding suitable habitats, 
navigating). Together, sounds made by animals and the geophysical 
environment (e.g., produced by earthquakes, lightning, wind, rain, 
waves) make up the natural contributions to the total acoustics of a 
place. These acoustic conditions, termed acoustic habitat, are one 
attribute of an animal's total habitat.
    Soundscapes are also defined by, and acoustic habitat influenced 
by, the total contribution of anthropogenic sound. This may include 
incidental emissions from sources such as vessel traffic, or may be 
intentionally introduced to the marine environment for data acquisition 
purposes (as in the use of airgun arrays). Anthropogenic noise varies 
widely in its frequency content, duration, and loudness and these 
characteristics greatly influence the potential habitat-mediated 
effects to marine mammals (please see also the previous discussion on 
masking under ``Acoustic Effects''), which may range from local effects 
for brief periods of time to chronic effects over large areas and for 
long durations. Depending on the extent of effects to habitat, animals 
may alter their communications signals (thereby potentially expending 
additional energy) or miss acoustic cues (either conspecific or 
adventitious). For more detail on these concepts see, e.g., Barber et 
al., 2010; Pijanowski et al. 2011; Francis and Barber 2013; Lillis et 
al. 2014.
    Problems arising from a failure to detect cues are more likely to 
occur when noise stimuli are chronic and overlap with biologically 
relevant cues used for communication, orientation, and predator/prey 
detection (Francis and Barber 2013). Although the signals emitted by 
seismic airgun arrays are generally low frequency, they would also 
likely be of short duration and transient in any given area due to the 
nature of these surveys. As described previously, exploratory surveys 
such as these cover a large area but would be transient rather than 
focused in a given location over time and therefore would not be 
considered chronic in any given location.
    In summary, activities associated with the proposed action are not 
likely to have a permanent, adverse effect on any fish habitat or 
populations of fish species or on the quality of acoustic habitat. 
Thus, any impacts to marine mammal habitat are not expected to cause 
significant or long-term consequences for individual marine mammals or 
their populations.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of whether the number of takes is ``small'' and the 
negligible impact determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as: Any act of 
pursuit, torment, or annoyance which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of the seismic airguns have the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory injury (Level A harassment) to result, primarily 
for high frequency cetaceans and phocid pinnipeds. Auditory injury is 
unlikely to occur for low- and mid-frequency species given very small 
modeled zones of injury for those species. The proposed mitigation and 
monitoring measures are expected to minimize the severity of such 
taking to the extent practicable. As described previously, no mortality 
is anticipated or proposed to be authorized for this activity. Below we 
describe how the take is estimated.
    Described in the most basic way, 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. Below, we describe these 
components in more detail and present the exposure estimate and 
associated numbers of take proposed for authorization.

Acoustic Thresholds

    Using the best available science, NMFS has developed 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. 2011). Based on the best available science and the 
practical need to use a threshold based on a factor that is both 
predictable and measurable for most activities, NMFS uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS predicts that marine mammals are likely to 
be behaviorally harassed in a manner we consider to fall under Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g. 
vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms) 
for non-explosive impulsive (e.g., seismic airguns) or intermittent 
(e.g., scientific sonar) sources. SIO's proposed activity includes the 
use of impulsive seismic sources. Therefore, the 160 dB re 1 [mu]Pa 
(rms) criteria is applicable for analysis of level B harassment.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (NMFS 2016) 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). The 
Technical Guidance identifies the received levels, or thresholds, above 
which individual marine mammals are predicted to experience changes in 
their hearing sensitivity for all underwater

[[Page 39295]]

anthropogenic sound sources, reflects the best available science, and 
better predicts the potential for auditory injury than does NMFS' 
historical criteria.
    These thresholds were developed by compiling and synthesizing the 
best available science and soliciting input multiple times from both 
the public and peer reviewers to inform the final product, and are 
provided in Table 4 below. The references, analysis, and methodology 
used in the development of the thresholds are described in NMFS 2016 
Technical Guidance, which may be accessed at: www.nmfs.noaa.gov/pr/acoustics/guidelines.htm. As described above, SIO's proposed activity 
includes the use of intermittent and impulsive seismic sources.

            Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift in Marine Mammals
----------------------------------------------------------------------------------------------------------------
                                                                  PTS onset thresholds
             Hearing group             -------------------------------------------------------------------------
                                                     Impulsive*                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans..........  Lpk,flat: 219 dB...................  LE,LF,24h: 199 dB.
                                        LE,LF,24h: 183 dB..................
Mid-Frequency (MF) Cetaceans..........  Lpk,flat: 230 dB...................  LE,MF,24h: 198 dB.
                                        LE,MF,24h: 185 dB..................
High-Frequency (HF) Cetaceans.........  Lpk,flat: 202 dB...................  LE,HF,24h: 173 dB.
                                        LE,HF,24h: 155 dB..................
Phocid Pinnipeds (PW) (Underwater)....  Lpk,flat: 218 dB...................  LE,PW,24h: 201 dB.
                                        LE,PW,24h: 185 dB..................
Otariid Pinnipeds (OW) (Underwater)...  Lpk,flat: 232 dB...................  LE,OW,24h: 219 dB.
                                        LE,OW,24h: 203 dB..................
----------------------------------------------------------------------------------------------------------------
Note: *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]Pa2s. 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 estimating the area ensonified above the 
acoustic thresholds.
    The proposed survey would entail the use of a 2-airgun array with a 
total discharge of 90 in\3\ at a tow depth of 3 m. The distance to the 
predicted isopleth corresponding to the threshold for Level B 
harassment (160 dB re 1 [mu]Pa) was calculated based on results of 
modeling performed by LDEO. Received sound levels were predicted by 
LDEO's model (Diebold et al. 2010) as a function of distance from the 
airgun array. The LDEO modeling approach uses ray tracing for the 
direct wave traveling from the array to the receiver and its associated 
source ghost (reflection at the air-water interface in the vicinity of 
the array), in a constant-velocity half-space (infinite homogeneous 
ocean layer unbounded by a seafloor). In addition, propagation 
measurements of pulses from a 36-airgun array at a tow depth of 6 m 
have been reported in deep water (~1,600 m), intermediate water depth 
on the slope (~600-1100 m), and shallow water (~50 m) in the Gulf of 
Mexico in 2007-2008 (Tolstoy et al. 2009; Diebold et al. 2010). The 
estimated distances to the Level B harassment isopleth for the Revelle 
airgun array are shown in Table 5.

  Table 5--Predicted Radial Distances From R/V Revelle 90 in\3\ Seismic
    Source to Isopleth Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
                                                             Predicted
                                                            distance to
                       Water depth                           threshold
                                                           (160 dB re 1
                                                              [mu]Pa)
------------------------------------------------------------------------
> 1000 m................................................           448 m
100-1000 m..............................................           672 m
------------------------------------------------------------------------

    For modeling of radial distances to predicted isopleths 
corresponding to harassment thresholds in deep water (>1,000 m), LDEO 
used the deep-water radii for various Sound Exposure Levels obtained 
from LDEO model results down to a maximum water depth of 2,000 m (see 
Figure 2 in the IHA application). Radial distances to predicted 
isopleths corresponding to harassment thresholds in intermediate water 
depths (100-1,000 m) were derived by LDEO from the deep-water distances 
by applying a correction factor (multiplication) of 1.5, such that 
observed levels at very near offsets fall below the corrected 
mitigation curve (Fig. 16 in Appendix H of NSF-USGS 2011). LDEO's 
modeling methodology is described in greater detail in the IHA 
application (LGL 2017) and we refer to the reader to that document 
rather than repeating it here.
    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal functional hearing groups (Table 3), were 
calculated based on modeling performed by LDEO using the Nucleus 
software program and the NMFS User Spreadsheet, described below. The 
updated acoustic thresholds for impulsive sounds (such as airguns) 
contained in the Technical Guidance (NMFS 2016) were presented as dual 
metric acoustic thresholds using both SELcum and peak sound 
pressure level metrics. 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

[[Page 39296]]

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 Revelle 
airgun array were derived from calculating the modified farfield 
signature (Table 6). 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 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. Though the array effect is not expected 
to be as pronounced in the case of a 2-airgun array as it would be with 
a larger airgun array, the modified farfield method is considered more 
appropriate than use of the theoretical farfield signature.

  Table 6--Modeled Source Levels Using Modified Farfield Method for R/V
                      Revelle 90 in\3\ Airgun Array
------------------------------------------------------------------------
    Functional Hearing Group         Peak SPLflat           SELcum
------------------------------------------------------------------------
Low frequency cetaceans          232.805 dB.........  206.0165 dB.
 (Lpk,flat: 219 dB; LE,LF,24h:
 183 dB).
Mid frequency cetaceans          229.89 dB..........  205.9638 dB.
 (Lpk,flat: 230 dB; LE,MF,24h:
 185 dB).
High frequency cetaceans         232.867 dB.........  206.384 dB.
 (Lpk,flat: 202 dB; LE,HF,24h:
 155 dB).
Phocid Pinnipeds (Underwater)    232.356 dB.........  205.9638 dB.
 (Lpk,flat: 218 dB; LE,HF,24h:
 185 dB).
Otariid Pinnipeds (Underwater)   224.7897 dB........  206.806 dB.
 (Lpk,flat: 232 dB; LE,HF,24h:
 203 dB).
------------------------------------------------------------------------

    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 Revelle's airgun array (modeled in 1 
Hz bands) was used to make adjustments (dB) to the unweighted spectrum 
levels, by frequency, according to the weighting functions for each 
relevant marine mammal hearing group. These adjusted/weighted spectrum 
levels were then converted to pressures ([mu]Pa) in order to integrate 
them over the entire broadband spectrum, resulting in broadband 
weighted source levels by hearing group that could be directly 
incorporated within the User Spreadsheet (i.e., to override the 
Spreadsheet's more simple weighting factor adjustment). Using the User 
Spreadsheet's ``safe distance'' methodology for mobile sources 
(described by Sivle et al., 2014) with the hearing group-specific 
weighted source levels, and inputs assuming spherical spreading 
propagation, a source velocity of 2.57 meters/second, and shot interval 
of 7.78 seconds (LGL 2017), potential radial distances to auditory 
injury zones were then calculated for SELcum thresholds. 
Inputs to the User Spreadsheet are shown in Table 6. Outputs from the 
User Spreadsheet in the form of estimated distances to Level A 
harassment isopleths are shown in Table 7. As described above, the 
larger distance of the dual criteria (SELcum or Peak 
SPLflat) is used for estimating takes by Level A harassment. 
The weighting functions used are shown in Table 3 of the IHA 
application.

 Table 7--Modeled Radial Distances (m) From R/V Revelle 90 in\3\ Airgun
    Array to Isopleths Corresponding to Level A Harassment Thresholds
------------------------------------------------------------------------
    Functional Hearing Group (Level A      Peak SPLflat
         harassment thresholds)                               SELcum
------------------------------------------------------------------------
Low frequency cetaceans (Lpk,flat: 219               4.9             7.9
 dB; LE,LF,24h: 183 dB).................
Mid frequency cetaceans (Lpk,flat: 230               0.9               0
 dB; LE,MF,24h: 185 dB).................
High frequency cetaceans (Lpk,flat: 202             34.9               0
 dB; LE,HF,24h: 155 dB).................
Phocid Pinnipeds (Underwater) (Lpk,flat:             5.2             0.1
 218 dB; LE,HF,24h: 185 dB).............
Otariid Pinnipeds (Underwater)                       0.4               0
 (Lpk,flat: 232 dB; LE,HF,24h: 203 dB)..
------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used, isopleths produced may be overestimates to some degree, 
which will ultimately result in some degree of overestimate of Level A 
take. However, these tools offer the best way to predict appropriate 
isopleths when more sophisticated 3D 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.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations.
    The best available scientific information was considered in 
conducting marine mammal exposure estimates (the basis for estimating 
take). For most cetacean species, densities calculated by Barlow (2016) 
were used.

[[Page 39297]]

These represent the most comprehensive and recent density data 
available for cetacean species in slope and offshore waters of Oregon 
and Washington and are based on data collected via NMFS Southwest 
Fisheries Science Center (SWFSC) ship-based surveys in 1991, 1993, 
1996, 2001, 2005, 2008, and 2014. The surveys were conducted up to ~556 
km from shore from June or August to November or December. The 
densities from NMFS SWFSC vessel-based surveys were corrected by the 
authors for both trackline detection probability and availability bias. 
Trackline detection probability bias is associated with diminishing 
sightability with increasing lateral distance from the trackline and is 
measured by f(0). Availability bias refers to the fact that there is 
less than 100 percent probability of sighting an animal that is present 
along the survey trackline, and it is measured by g(0). Abundance and 
density were not estimated for gray whales or harbor porpoises in the 
NMFS SWFSC surveys because their inshore habitats were inadequately 
covered in those studies. Gray whale density is derived from the 
abundance of gray whales that remain between Oregon and British 
Columbia in summer (updated based on abundance calculated by 
Calambokidis et al. 2014) and the area out to 43 km from shore, using 
the U.S. Navy (2010) method. Harbor porpoise densities are based on 
data from aerial line-transect surveys during 2007-2012 for the 
Northern Oregon/Washington Coast stock (Forney et al. 2014).
    Systematic, offshore, at-sea survey data for pinnipeds are more 
limited than those for cetaceans. Densities for the Steller sea lion, 
California sea lion, northern elephant seal, and northern fur seal were 
calculated using the methods in U.S. Navy (2010) with updated abundance 
estimates from Carretta et al. (2016) and Muto et al. (2016), when 
appropriate. For the harbor seal, densities were calculated using the 
population estimate for the Oregon/Washington Coastal stock and the 
range for that stock from Carretta et al. (2016).
    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 is based on the best available 
data.

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 B harassment or Level A harassment, radial 
distances to predicted isopleths corresponding to the Level A 
harassment and Level B harassment thresholds are calculated, as 
described above. We then use those distances 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 total 
ensonified area for the survey is then calculated, based on the areas 
predicted to be ensonified around the array and the trackline distance. 
In this case, 25 percent was added in the form of operational days, 
which is equivalent to adding 25 percent to the proposed line km to be 
surveyed, to account for potential additional seismic operations as 
described above. The marine mammals predicted to occur within the 
ensonified areas, based on estimated densities, are expected to be 
incidentally taken by the proposed survey.
    To summarize, the estimated density of each marine mammal species 
within an area (animals/km\2\) is multiplied by the total ensonified 
areas (km\2\) that correspond to the Level A and Level B harassment 
thresholds for the species. The product (rounded) is the estimated 
number of instances of take for each species . The number of instances 
of take for each species is then multiplied by 1.25 to account for the 
25 percent contingency, as described above. The result is an estimate 
of the number of instances that marine mammals are predicted to be 
exposed to airgun sounds above the Level B harassment threshold and the 
Level A harassment threshold over the duration of the proposed survey. 
The total area estimated to be ensonified to the Level B harassment 
threshold for the proposed survey is 204.2 km\2\. Estimated takes for 
all marine mammal species are shown in Table 8.

                               Table 8--Numbers of Potential Incidental Take of Marine Mammals Proposed for Authorization
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                          Total proposed
                                                                                                                                            Level A and
                                                            Density (#/    Estimated and     Estimated    Proposed Level  Total proposed   Level B takes
                         Species                           1,000 km\2\)   proposed Level   Level B takes      B takes       Level A and        as a
                                                                              A takes                                      Level B takes   percentage of
                                                                                                                                            population
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray whale..............................................             2.6               0               4               4               4           < 0.1
Humpback whale..........................................             2.1               0               3               3               3             0.2
Minke whale.............................................             1.3               0               2               2               2             0.3
Sei whale \1\...........................................             0.4               0               1               2               2             0.4
Fin whale...............................................             4.2               0               6               6               6           < 0.1
Blue whale..............................................             0.3               0               1               1               1           < 0.1
Sperm whale \1\.........................................             0.9               0               2               6               6             0.3
Pygmy sperm whale.......................................             1.6               0               2               2               2           < 0.1
Killer whale \1\........................................             0.9               0               2               8               8
    West coast transient stock..........................  ..............  ..............  ..............  ..............             3.3
    Eastern No. Pacific offshore stock..................  ..............  ..............  ..............  ..............  ..............             3.3
False killer whale \1\..................................               0               0               0               5               5             0.3
Short-finned pilot whale \1\............................             0.2               0               0               1              18             2.2
Harbor porpoise.........................................           467.0              44             582             582             627
    No.California/So. Oregon stock......................  ..............  ..............  ..............  ..............  ..............             1.8
    Northern Oregon/Washington coast stock..............  ..............  ..............  ..............  ..............  ..............             2.9
Dall's porpoise.........................................            54.4               5              68              68              73             0.3
Bottlenose dolphin \1\..................................               0               0               0               0              13             6.8
Striped dolphin \1\.....................................             7.7               0              10             109             109             3.7
Risso's dolphin \1\.....................................            11.8               0              16              28              28             4.4
Short-beaked common dolphin \1\.........................            69.2               0              89             286             286           < 0.1
Pacific white sided dolphin \1\.........................            40.7               0              52              62              62             2.3

[[Page 39298]]

 
Northern right whale dolphin \1\........................            46.4               0              60              63              63             2.5
Cuvier's beaked whale...................................             2.8               0               4               4               4           < 0.1
Baird's beaked whale....................................            10.7               0              14              14              14             1.7
Mesoplodont beaked whales \2\...........................             1.2               0               2               2               2             2.9
California sea lion.....................................           283.3               0             362             362             362             1.2
Steller sea lion........................................            15.0               0              20              20              20           < 0.1
Harbor seal.............................................           292.3               4             367             367             371             1.5
Northern elephant seal..................................            83.1               1             105             105             106           < 0.1
Northern fur seal.......................................            83.4               0             107             107             107             0.8
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The proposed number of authorized takes (Level B harassment only) for these species has been increased from the estimated take to mean group size
  (as reported in Barlow (2016)).
\2\ May be any of the following: Blainville's beaked whale, Perrin's beaked whale, Lesser beaked whale, Stejneger's beaked whale, Gingko-toothed beaked
  whale, or Hubb's beaked whale.

    Species With Take Estimates Less Than Mean Group Size: Using the 
approach described above to estimate take, the take estimates for the 
sei whale, sperm whale, killer whale, short-finned pilot whale, false 
killer whale, bottlenose dolphin, short beaked common dolphin, striped 
dolphin, Pacific white sided dolphin, Risso's dolphin and Northern 
right whale dolphin were less than the average group sizes estimated 
for these species (Table 8). However, information on the social 
structures and life histories of these species indicates it is common 
for these species to be encountered in groups. The results of take 
calculations support the likelihood that SIO's survey is expected to 
encounter and to incidentally take these species, and we believe it is 
likely that these species may be encountered in groups, therefore it is 
reasonable to conservatively assume that one group of each of these 
species will be taken during the proposed survey. We therefore propose 
to authorize the take of the average (mean) group size for these 
species and stocks to account for the possibility that SIO's survey 
encounters a group of any of these species or stocks (Table 8).
    No density data were available for the false killer whale or the 
bottlenose dolphin in the proposed survey area, as these species are 
not typically observed in the proposed survey area (Carretta et al. 
2017). However, we believe it is possible that these species may be 
encountered by SIO during the proposed survey. Though false killer 
whales are a tropical species that is usually found in waters warmer 
than those typical of the proposed survey area, they have been observed 
off the U.S. west coast during warm-water periods. Several sightings 
were made off California during 2014-2016, when waters were unusually 
warm, and historically there are very rare records farther north (pers. 
comm. K. Forney, NMFS Southwest Fisheries Science Center, to J. 
Carduner, NMFS, July 27, 2017). Bottlenose dolphins have not been 
observed off the coast of Oregon and Washington (Carretta et al. 2017). 
However, they occur frequently off the coast of California, and they 
may range into Oregon and Washington waters during warm-water periods. 
(Carretta et al. 2017). Though no density data are available, we 
believe it is reasonable to conservatively assume that SIO's proposed 
survey may encounter and incidentally take false killer whales and 
bottlenose dolphins. We therefore propose to authorize the take of the 
average (mean) group size for both species (Table 8).
    It should be noted that the proposed take numbers shown in Table 8 
are believed to be conservative for several reasons. First, in the 
calculations of estimated take, 25 percent has been added in the form 
of operational survey days (equivalent to adding 25 percent to the 
proposed line km to be surveyed) to account for the possibility of 
additional seismic operations associated with airgun testing, and 
repeat coverage of any areas where initial data quality is sub-
standard. Additionally, marine mammals would be expected to move away 
from a sound source that represents an aversive stimulus. However, the 
extent to which marine mammals would move away from the sound source is 
difficult to quantify and is therefore not accounted for in take 
estimates shown in Table 8.
    For some marine mammal species, we propose to authorize a different 
number of incidental takes than the number of incidental takes 
requested by SIO (see Table 7 in the IHA application for requested take 
numbers). For instance, for several species, SIO increased the take 
request from the calculated take number to 1 percent of the estimated 
population size. However, we do not believe it is likely that 1 percent 
of the estimated population size of those species will be taken by 
SIO's proposed survey, therefore we propose to authorize take numbers 
as shows in Table 8, which we believe are based on the best available 
information.
    To calculate distances to isopleths corresponding to Level A 
harassment thresholds using Peak SPLflat, LDEO first ran the 
modeling for a single shot and then applied a high pass filter for each 
hearing group based on the group's generalized hearing range. A high 
pass filter is a type of band-pass filter, which pass frequencies 
within a defined range without reducing amplitude and attenuate 
frequencies outside that defined range (Yost 2007). LDEO ran the 
modeling both with and without the application of the high pass filter 
and SIO included information on isopleths corresponding to Level A 
harassment thresholds both with and without the high pass filter in 
their IHA application. The Technical Guidance referred to auditory 
weighting functions based on a generic band-pass filter (NMFS 2016). 
However, it is important to note that the two datasets relied upon to 
define peak sound pressure level thresholds, either directly or as a 
surrogate means to derive thresholds for groups where no data are 
available (i.e., a beluga exposed to seismic water gun and harbor 
porpoise exposed to a single airgun) did not use a filter of any kind 
(i.e., thresholds provided were flat across the entire spectrum of the 
sound source). Therefore, for the purposes of modeling isopleths 
corresponding to Level A harassment thresholds using Peak

[[Page 39299]]

SPLflat, NMFS believes that sound produced from the Revelle 
airgun array should be considered flat to result in no weighting/high 
pass filtering of any type at this time. Therefore, for the purposes of 
the take calculation, we rely on the distances to isopleths 
corresponding to Level A harassment thresholds using Peak 
SPLflat based on modeling performed by LDEO without the high 
pass filter applied. Thus, the proposed Level A take numbers shown in 
Table 8 for harbor porpoise, Dall's porpoise and harbor seal are higher 
than the Level A take numbers requested by SIO as they are the result 
of modeling of isopleths corresponding to Level A harassment thresholds 
using Peak SPLflat with no weighting/high pass filtering 
applied. Level A take numbers for other species are not affected.

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 such 
activity, ``and other means of effecting the least practicable impact 
on such species or stock and its habitat, paying particular attention 
to rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking'' for 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 such 
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.
    SIO has reviewed mitigation measures employed during seismic 
research surveys authorized by NMFS under previous incidental 
harassment authorizations, as well as recommended best practices in 
Richardson et al. (1995), Pierson et al. (1998), Weir and Dolman 
(2007), Nowacek et al. (2013), Wright (2014), and Wright and Cosentino 
(2015), and has incorporated a suite of proposed mitigation measures 
into their project description based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, SIO has proposed to implement the 
following mitigation measures for marine mammals:
    (1) Vessel-based visual mitigation monitoring;
    (2) Establishment of an exclusion zone and buffer zone;
    (3) Shutdown procedures;
    (4) Ramp-up procedures; and
    (5) Ship strike avoidance measures.
    In addition to these measures, NMFS proposes the following 
additional mitigation measure:
    (1) Shutdown for killer whales observed at any distance.

Vessel-Based Visual Mitigation Monitoring

    PSO observations would take place during all daytime airgun 
operations and nighttime start ups (if applicable) of the airguns. If 
airguns are operating throughout the night, observations would begin 30 
minutes prior to sunrise. If airguns are operating after sunset, 
observations would continue until 30 minutes following sunset. 
Following a shutdown for any reason, observations would occur for at 
least 30 minutes prior to the planned start of airgun operations. 
Observations would also occur for 30 minutes after airgun operations 
cease for any reason. Observations would also be made during daytime 
periods when the Revelle is underway without seismic operations, such 
as during transits, to allow for comparison of sighting rates and 
behavior with and without airgun operations and between acquisition 
periods. Airgun operations would be suspended when marine mammals are 
observed within, or about to enter, the designated Exclusion Zone (as 
described below).
    (i) During seismic operations, three visual PSOs would be based 
aboard the Revelle. PSOs would be appointed by SIO with NMFS approval. 
During the majority of seismic operations, two PSOs would monitor for 
marine mammals around the seismic vessel. A minimum of one PSO must be 
on duty at all times when the array is active. PSO(s) would be on duty 
in shifts of duration no longer than 4 hours. Other crew would also be 
instructed to assist in detecting marine mammals and in implementing 
mitigation requirements (if practical). Before the start of the seismic 
survey, the crew would be given additional instruction in detecting 
marine mammals and implementing mitigation requirements.
    The Revelle is a suitable platform from which PSOs would watch for 
marine mammals. The Revelle has been used for that purpose during the 
routine California Cooperative Oceanic Fisheries Investigations 
surveys. Observing stations are located at the 02 level, with the 
observer eye level at ~10.4 m above the waterline. At a forward-
centered position on the 02 deck, the view is ~240[deg]; an aft-
centered view includes the 100-m radius area around the GI airguns. The 
observer eye level on the bridge is ~15 m above sea level. Standard 
equipment for marine mammal observers would be 7 x 50 reticule 
binoculars and optical range finders. At night, night-vision equipment 
would be available. The observers would be in communication with ship's 
officers on the bridge and scientists in the vessel's operations 
laboratory, so they can advise promptly of the need for avoidance 
maneuvers or seismic source shutdown.
    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 would be provided to NMFS for 
approval. At least one PSO must have a minimum of 90 days at-sea 
experience working as PSOs during a deep penetration seismic survey, 
with no more than eighteen months elapsed since the conclusion of the 
at-sea experience. One ``experienced'' visual PSO would be designated 
as the lead for the entire protected species observation team. The lead 
would serve as primary point of contact for the vessel operator.
    The PSOs must have successfully completed relevant training, 
including completion of all required coursework and passing a written 
and/or oral

[[Page 39300]]

examination developed for the training program, and must have 
successfully attained a bachelor's degree from an accredited college or 
university with a major in one of the natural sciences and a minimum of 
30 semester hours or equivalent in the biological sciences and at least 
one undergraduate course in math or statistics. The educational 
requirements may be waived if the PSO has acquired the relevant skills 
through alternate training, including (1) secondary education and/or 
experience comparable to PSO duties; (2) previous work experience 
conducting academic, commercial, or government-sponsored marine mammal 
surveys; or (3) previous work experience as a PSO; the PSO should 
demonstrate good standing and consistently good performance of PSO 
duties.

Exclusion Zone (EZ) and Buffer Zone

    An exclusion zone 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 exclusion zone 
with a 100 m radius for the airgun array. The 100 m EZ would be based 
on radial distance from any element 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, enters, or appears on a course to enter this zone, the acoustic 
source would be shut down (see Shut Down Procedures below).
    The 100 m radial distance of the standard EZ is precautionary in 
the sense that it would be expected to contain sound exceeding peak 
pressure injury criteria for all marine mammal hearing groups (Table 7) 
while also providing a consistent, reasonably observable zone within 
which PSOs would typically be able to conduct effective observational 
effort. In this case, the 100 m radial distance would also be expected 
to contain sound that would exceed the Level A harassment threshold 
based on sound exposure level (SELcum) criteria for all 
marine mammal hearing groups (Table 7). In the 2011 Programmatic 
Environmental Impact Statement for marine scientific research funded by 
NSF or the U.S. Geological Survey (NSF-USGS 2011), Alternative B (the 
Preferred Alternative) conservatively applied a 100 m EZ for all low-
energy acoustic sources in water depths >100 m, with low-energy 
acoustic sources defined as any towed acoustic source with a single or 
a pair of clustered airguns with individual volumes of <=250 in\3\. 
Thus the 100 m EZ proposed for this survey is consistent with the PEIS.
    Our intent in prescribing a standard exclusion zone distance is to 
(1) encompass zones within which auditory injury could occur on the 
basis of instantaneous exposure; (2) provide additional protection from 
the potential for more severe behavioral reactions (e.g., panic, 
antipredator response) for marine mammals at relatively close range to 
the acoustic source; (3) provide consistency for PSOs, who need to 
monitor and implement the EZ; and (4) define a distance within which 
detection probabilities are reasonably high for most species under 
typical conditions.
    PSOs would also establish and monitor a 200 m buffer zone. During 
use of the acoustic source, occurrence of marine mammals within the 
buffer zone (but outside the exclusion zone) would be communicated to 
the operator to prepare for potential shutdown of the acoustic source. 
The buffer zone is discussed further under Ramp Up Procedures below.

Shutdown Procedures

    If a marine mammal is detected outside the EZ but is likely to 
enter the EZ, and if the vessel's speed and/or course cannot be changed 
to avoid having the animal enter the EZ, the airguns would be shut down 
before the animal is within the EZ. Likewise, if a marine mammal is 
already within the EZ when first detected, the airguns would be shut 
down immediately.
    Following a shutdown, airgun activity would not resume until the 
marine mammal has cleared the 100 m EZ. The animal would be considered 
to have cleared the 100 m EZ if the following conditions have been met:
     It is visually observed to have departed the 100 m EZ, or
     it has not been seen within the 100 m EZ for 15 min in the 
case of small odontocetes, or
     it has not been seen within the 100 m EZ for 30 min in the 
case of mysticetes and large odontocetes, including sperm, pygmy sperm, 
and beaked whales.
    This shutdown requirement would be in place for all marine mammals, 
with the exception of small delphinoids under certain circumstances. As 
defined here, the small delphinoid 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 would apply solely to specific genera of small dolphins -- 
Tursiops, Stenella, Delphinus, Lagenorhynchus and Lissodelphis -- and 
would only apply if the animals were traveling, including approaching 
the vessel. If, for example, an animal or group of animals is 
stationary for some reason (e.g., feeding) and the source vessel 
approaches the animals, the shutdown requirement applies. An animal 
with sufficient incentive to remain in an area rather than avoid an 
otherwise aversive stimulus could either incur auditory injury or 
disruption of important behavior. If there is uncertainty regarding 
identification (i.e., whether the observed animal(s) belongs to the 
group described above) or whether the animals are traveling, the 
shutdown would be implemented.
    We propose this small delphinoid exception because shutdown 
requirements for small delphinoids under all circumstances represent 
practicability concerns without likely commensurate benefits for the 
animals in question. Small delphinoids 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 below, 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). Please see ``Potential Effects of the Specified Activity on 
Marine Mammals'' above for further discussion of sound metrics and 
thresholds and marine mammal hearing.
    A large body of anecdotal evidence indicates that small delphinoids 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinoids (e.g., Barkaszi et al., 2012). The potential for 
increased shutdowns resulting from such a measure would require the 
Revelle to revisit the missed track line to reacquire data, resulting 
in an overall increase in the total sound energy input to the marine 
environment and an increase in the total duration over which the survey 
is active in a given area. Although other mid-frequency hearing 
specialists (e.g., large delphinoids) are no more likely to incur 
auditory injury than are small delphinoids, they are much less likely 
to approach vessels. Therefore, retaining a shutdown requirement for 
large delphinoids would not have similar impacts in terms of either 
practicability

[[Page 39301]]

for the applicant or corollary increase in sound energy output and time 
on the water. We do anticipate some benefit for a shutdown requirement 
for large delphinoids in that it simplifies somewhat the total range of 
decision-making for PSOs and may preclude any potential for 
physiological effects other than to the auditory system as well as some 
more severe behavioral reactions for any such animals in close 
proximity to the source vessel.
    At any distance, shutdown of the acoustic source would also be 
required upon observation of any of the following:
     A killer whale;
     a large whale (i.e., sperm whale or any baleen whale) with 
a calf; or
     an aggregation of large whales of any species (i.e., sperm 
whale or any baleen whale) that does not appear to be traveling (e.g., 
feeding, socializing, etc.).
    These would be the only three potential situations that would 
require shutdown of the array for marine mammals observed beyond the 
100 m EZ. Southern Resident DPS killer whales are not expected to occur 
in the area of the proposed survey as the easternmost track lines of 
the proposed survey (those that approach nearest to shore) are further 
west than the migratory range of the Southern Resident stock off Oregon 
and southern Washington (pers. comm., B. Hanson, NMFS Northwest Fishery 
Science Center to J. Carduner, NMFS OPR, April 12, 2017). As the 
Eastern North Pacific Southern Resident stock would be expected to 
occur closer to shore than the proposed survey area, the survey is not 
expected to encounter any individuals from this stock. However, as the 
known migratory range of the Southern Resident DPS occurs near the 
proposed survey area, and due to the precarious conservation status of 
the Southern Resident killer whale DPS, NMFS believes it is reasonable 
to implement measures that are conservative and also practicable in 
order to prevent the potential for a Southern Resident killer whale to 
be exposed to airgun sounds. Thus the requirement to shut down the 
array upon observation of a killer whale at any distance is designed to 
avoid any potential for harassment of any Southern Resident killer 
whales.

Ramp-Up Procedures

    Ramp-up of an acoustic source is intended to provide a gradual 
increase in sound levels following a shutdown, enabling animals to move 
away from the source if the signal is sufficiently aversive prior to 
its reaching full intensity. Ramp-up would be required after the array 
is shut down for any reason. Ramp-up would begin with the activation of 
one 45 in\3\ airgun, with the second 45 in\3\ airgun activated after 5 
minutes.
    PSOs would be required to monitor during ramp-up. During ramp up, 
the PSOs would monitor the EZ, and if marine mammals were observed 
within or approaching the 100 m EZ, a shutdown would be implemented as 
though the full array were operational. If airguns have been shut down 
due to PSO detection of a marine mammal within or approaching the 100 m 
EZ, ramp-up would not be initiated until all marine mammals have 
cleared the EZ, during the day or night. Criteria for clearing the EZ 
would be as described above.
    Thirty minutes of pre-clearance observation are required prior to 
ramp-up for any shutdown of longer than 30 minutes (i.e., if the array 
were shut down during transit from one line to another). This 30 minute 
pre-clearance period may occur during any vessel activity (i.e., 
transit). If a marine mammal were observed within or approaching the 
100 m EZ during this pre-clearance period, ramp-up would not be 
initiated until all marine mammals cleared the EZ. Criteria for 
clearing the EZ would be as described above. If the airgun array has 
been shut down for reasons other than mitigation (e.g., mechanical 
difficulty) for a period of less than 30 minutes, it may be activated 
again without ramp-up if PSOs have maintained constant visual 
observation and no detections of any marine mammal have occurred within 
the EZ or buffer zone. Ramp-up would be planned to occur during periods 
of good visibility when possible. However, ramp-up would be allowed at 
night and during poor visibility if the 100 m EZ and 200 m buffer zone 
have been monitored by visual PSOs for 30 minutes prior to ramp-up.
    The operator would be required to 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. A designated PSO must be notified again immediately 
prior to initiating ramp-up procedures and the operator must receive 
confirmation from the PSO to proceed. The operator must provide 
information to PSOs documenting that appropriate procedures were 
followed. Following deactivation of the array for reasons other than 
mitigation, the operator would be required to communicate the near-term 
operational plan to the lead PSO with justification for any planned 
nighttime ramp-up.

Speed or Course Alteration

    If a marine mammal is detected outside the EZ, based on its 
position and the relative motion, is likely to enter the EZ, the 
vessel's speed and/or direct course could be changed. This would be 
done if operationally practicable while minimizing the effect on the 
planned science objectives. The activities and movements of the marine 
mammal (relative to the seismic vessel) would then be closely monitored 
to determine whether the animal is approaching the EZ. If the animal 
appears likely to enter the EZ, a shutdown of the seismic source would 
cocur. Typically, during seismic operations, the source vessel is 
unable to change speed or course and one or more alternative mitigation 
measures (as described above) would need to be implemented.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the proposed 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

[[Page 39302]]

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).
     Mitigation and monitoring effectiveness.
    SIO submitted a marine mammal monitoring and reporting plan in 
section XIII of their IHA application. Monitoring that is designed 
specifically to facilitate mitigation measures, such as monitoring of 
the EZ to inform potential shutdowns of the airgun array, are described 
above and are not repeated here.
    SIO's monitoring and reporting plan includes the following 
measures:

Vessel-Based Visual Monitoring

    As described above, PSO observations would take place during 
daytime airgun operations and nighttime start ups (if applicable) of 
the airguns. During seismic operations, three visual PSOs would be 
based aboard the Revelle. PSOs would be appointed by SIO with NMFS 
approval. During the majority of seismic operations, one PSO would 
monitor for marine mammals around the seismic vessel. PSOs would be on 
duty in shifts of duration no longer than 4 hours. Other crew would 
also be instructed to assist in detecting marine mammals and in 
implementing mitigation requirements (if practical). During daytime, 
PSOs would scan the area around the vessel systematically with reticle 
binoculars (e.g., 7 x 50 Fujinon), Big-eye binoculars (25 x 150), and 
with the naked eye.
    PSOs would record data to estimate the numbers of marine mammals 
exposed to various received sound levels and to document apparent 
disturbance reactions or lack thereof. Data would be used to estimate 
numbers of animals potentially `taken' by harassment (as defined in the 
MMPA). They would also provide information needed to order a shutdown 
of the airguns when a marine mammal is within or near the EZ. When a 
sighting is made, the following information about the sighting would be 
recorded:
    1. Species, group size, age/size/sex categories (if determinable), 
behavior when first sighted and after initial sighting, heading (if 
consistent), bearing and distance from seismic vessel, sighting cue, 
apparent reaction to the airguns or vessel (e.g., none, avoidance, 
approach, paralleling, etc.), and behavioral pace.
    2. Time, location, heading, speed, activity of the vessel, sea 
state, visibility, and sun glare.
    All observations and shutdowns would be recorded in a standardized 
format. Data would be entered into an electronic database. The accuracy 
of the data entry would be verified by computerized data validity 
checks as the data are entered and by subsequent manual checking of the 
database. These procedures would allow initial summaries of data to be 
prepared during and shortly after the field program and would 
facilitate transfer of the data to statistical, graphical, and other 
programs for further processing and archiving. The time, location, 
heading, speed, activity of the vessel, sea state, visibility, and sun 
glare would also be recorded at the start and end of each observation 
watch, and during a watch whenever there is a change in one or more of 
the variables.
    Results from the vessel-based observations would provide:
    1. The basis for real-time mitigation (airgun shutdown).
    2. Information needed to estimate the number of marine mammals 
potentially taken by harassment, which must be reported to NMFS.
    3. Data on the occurrence, distribution, and activities of marine 
mammals in the area where the seismic study is conducted.
    4. Information to compare the distance and distribution of marine 
mammals relative to the source vessel at times with and without seismic 
activity.
    5. Data on the behavior and movement patterns of marine mammals 
seen at times with and without seismic activity.

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' 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 the species listed 
in Table 2, given that NMFS expects the anticipated effects of the 
proposed seismic 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 SIO's proposed seismic survey, even in the absence 
of proposed mitigation. Thus the proposed authorization does not 
authorize any mortality. As discussed in the Potential Effects section, 
non-auditory physical effects, stranding, and vessel strike are not 
expected to occur.
    We propose to authorize a limited number of instances of Level A 
harassment (Table 8) for four species. However, we believe that any PTS 
incurred in marine mammals as a result of the proposed activity would 
be in the form of only a small degree of PTS and not total deafness 
that would not be likely to affect the fitness of any individuals, 
because of the constant movement of both the Revelle and of the marine 
mammals in the project area, as well as the fact that the vessel is not 
expected to remain in any one area in which individual marine mammals

[[Page 39303]]

would be expected to concentrate for an extended period of time (i.e., 
since the duration of exposure to loud sounds will be relatively 
short). Also, as described above, we expect that marine mammals would 
be likely to move away from a sound source that represents an aversive 
stimulus, especially at levels that would be expected to result in PTS, 
given sufficient notice of the Revelle'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).
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see Potential Effects of the Specified 
Activity on Marine Mammals and their Habitat). Marine mammal habitat 
may be impacted by elevated sound levels, but these impacts would be 
temporary. Feeding behavior is not likely to be significantly impacted, 
as marine mammals appear to be less likely to exhibit behavioral 
reactions or avoidance responses while engaged in feeding activities 
(Richardson et al., 1995). Prey species are mobile and are broadly 
distributed throughout the project area; therefore, marine mammals that 
may be temporarily displaced during survey activities are expected to 
be able to resume foraging once they have moved away from areas with 
disturbing levels of underwater noise. Because of the temporary nature 
of the disturbance, the availability of similar habitat and resources 
in the surrounding area, and the lack of important or unique marine 
mammal habitat, 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. In 
addition, there are no mating or calving areas known to be biologically 
important to marine mammals within the proposed project area.
    The activity is expected to impact a very small percentage of all 
marine mammal stocks that would be affected by SIO's proposed survey 
(less than 7 percent each for all marine mammal stocks). Additionally, 
the acoustic ``footprint'' of the proposed survey would be very small 
relative to the ranges of all 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. The seismic array 
would be active 24 hours per day throughout the duration of the 
proposed survey. However, the very brief overall duration of the 
proposed survey (five days) would further limit potential impacts that 
may occur as a result of the proposed activity.
    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 some extent of potential PTS in marine mammals that may otherwise 
occur in the absence of the proposed mitigation.
    Of the marine mammal species under our jurisdiction that are likely 
to occur in the project area, the following species are listed as 
endangered under the ESA: Humpback, blue, fin, sei, and sperm whales. 
Population estimates for humpback whales for the North Pacific have 
increased substantially from 1,200 in 1966 to approximately 18,000-
20,000 whales in 2004 to 2006 (Calambokidis et al. 2008) indicating a 
growth rate of 6-7 percent (Carretta et al., 2017). There are currently 
insufficient data to determine population trends for blue, fin, sei, 
and sperm whales (Carretta et al., 2017); however, we are proposing to 
authorize very small numbers of takes for these species (Table 8), 
relative to their population sizes, therefore we do not expect 
population-level impacts to any of these species. The other marine 
mammal species that may be taken by harassment during SIO's seismic 
survey are not listed as threatened or endangered under the ESA. There 
is no designated critical habitat for any ESA-listed marine mammals 
within the project area; and of the non-listed marine mammals for which 
we propose to authorize take, none are considered ``depleted'' or 
``strategic'' by NMFS under the MMPA.
    NMFS concludes that exposures to marine mammal species and stocks 
due to SIO's proposed seismic survey would result in only short-term 
(temporary and short in duration) effects to individuals exposed, or 
some small degree of PTS to a very small number of individuals of four 
species.. 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 marine mammal 
species or stocks through effects on annual rates of recruitment or 
survival:
     No mortality is anticipated or authorized;
     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 relatively short 
duration of the proposed survey (5 days) would further limit the 
potential impacts of any temporary behavioral changes that would occur;
     The number of instances of PTS that may occur are expected 
to be very small in number (Table 8). Instances of PTS that are 
incurred in marine mammals would 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 proposed project area does not contain areas of 
significance for feeding, mating or calving;
     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;
     The proposed mitigation measures, including visual and 
acoustic monitoring and shutdowns, are expected to minimize potential 
impacts to marine mammals.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under Section 101(a)(5)(D) of the MMPA

[[Page 39304]]

for specified activities other than military readiness activities. The 
MMPA does not define small numbers; so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. Additionally, other qualitative 
factors may be considered in the analysis, such as the temporal or 
spatial scale of the activities. Table 8 provides numbers of take by 
Level A harassment and Level B harassment proposed for authorization. 
These are the numbers we use for purposes of the small numbers 
analysis.
    The numbers of marine mammals that we propose for authorization to 
be taken, for all species and stocks, would be considered small 
relative to the relevant stocks or populations (approximately 6.8 
percent for bottlenose dolphins, and less than 5 percent for all other 
species and stocks). Based on the analysis contained herein of the 
proposed activity (including the proposed mitigation and monitoring 
measures) and the anticipated take of marine mammals, NMFS 
preliminarily finds that small numbers of marine mammals will be taken 
relative to the population size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
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 ESA of 1973 (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, in this case with the ESA Interagency Cooperation Division, 
whenever we propose to authorize take for endangered or threatened 
species.
    The NMFS Permits and Conservation Division is proposing to 
authorize the incidental take of 5 species of marine mammals which are 
listed under the ESA: The humpback whale (Mexico DPS), sei whale, fin 
whale, blue whale and sperm whale. We have requested initiation of 
Section 7 consultation with the Interagency Cooperation Division for 
the issuance of this IHA. NMFS will conclude the ESA section 7 
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 SIO for conducting a seismic survey in the northeast 
Pacific Ocean in September, 2017, provided the previously mentioned 
mitigation, monitoring, and reporting requirements are incorporated. 
This section contains a draft of the IHA itself. The wording contained 
in this section is proposed for inclusion in the IHA (if issued).
    1. This IHA is valid for a period of one year from the date of 
issuance.
    2. This IHA is valid only for marine geophysical survey activity, 
as specified in the SIO IHA application and using an airgun array 
aboard the R/V Revelle with characteristics specified in the 
application, in the northeast Pacific Ocean.
    3. General Conditions.
    (a) A copy of this IHA must be in the possession of SIO, the vessel 
operator and other relevant personnel, the lead PSO, and any other 
relevant designees of SIO operating under the authority of this IHA.
    (b) The species authorized for taking are listed in Table 8. The 
taking, by Level A and Level B harassment only, is limited to the 
species and numbers listed in Table 8. Any taking exceeding the 
authorized amounts listed in Table 8 is prohibited and may result in 
the modification, suspension, or revocation of this IHA.
    (c) The taking by serious injury or death of any species of marine 
mammal is prohibited and may result in the modification, suspension, or 
revocation of this IHA.
    (d) During use of the airgun(s), if marine mammal species other 
than those listed in Table 8 are detected by PSOs, the acoustic source 
must be shut down to avoid unauthorized take.
    (e) SIO shall ensure that the vessel operator and other relevant 
vessel personnel are briefed on all responsibilities, communication 
procedures, marine mammal monitoring protocol, operational procedures, 
and IHA requirements prior to the start of survey activity, and when 
relevant new personnel join the survey operations.
    4. Mitigation Requirements.
    The holder of this Authorization is required to implement the 
following mitigation measures:
    (b) SIO must use at least three (3) dedicated, trained, NMFS-
approved PSO. 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.
    (c) At least one PSO must have a minimum of 90 days at-sea 
experience working as a PSO during a deep penetration seismic survey, 
with no more than eighteen months elapsed since the conclusion of the 
at-sea experience. One ``experienced'' visual PSO 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.
    (d) Visual Observation.
    (i) During survey operations (e.g., any day on which use of the 
acoustic source is planned to occur; whenever the acoustic source is in 
the water, whether activated or not), typically two, and minimally one, 
PSO(s) 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).
    (ii) Visual monitoring must begin not less than 30 minutes prior to 
ramp-up, including for nighttime ramp-ups of the airgun array, and must 
continue until one hour after use of the acoustic source ceases or 
until 30 minutes past sunset.
    (iii) 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.
    (iv) 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 observation per 24 hour period.
    (v) During good conditions (e.g., daylight hours; Beaufort sea 
state 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.
    (e) Exclusion Zone and buffer zone--PSOs shall establish and 
monitor a 100 m EZ and 200 m buffer zone. The zones shall be based upon 
radial distance from

[[Page 39305]]

any element of the airgun array (rather than being based on the center 
of the array or around the vessel itself). During use of the acoustic 
source, occurrence of marine mammals outside the EZ but within 200 m 
from any element of the airgun array shall be communicated to the 
operator to prepare for potential further mitigation measures as 
described below. During use of the acoustic source, occurrence of 
marine mammals within the EZ, or on a course to enter the EZ, shall 
trigger further mitigation measures as described below.
    (i) Ramp-up--A ramp-up procedure, is required at all times as part 
of the activation of the acoustic source. Ramp-up would begin with one 
45 in\3\ airgun, and the second 45 in\3\ airgun would be added after 5 
minutes.
    (ii) If the airgun array has been shut down due to a marine mammal 
detection, ramp-up shall not occur until all marine mammals have 
cleared the EZ. A marine mammal is considered to have cleared the EZ 
if:
    (A) It has been visually observed to have left the EZ; or
    (B) It has not been observed within the EZ, for 15 minutes (in the 
case of small odontocetes) or for 30 minutes (in the case of mysticetes 
and large odontocetes including sperm, pygmy sperm, and beaked whales).
    (iii) Thirty minutes of pre-clearance observation of the 100 m EZ 
and 200 m buffer zone are required prior to ramp-up for any shutdown of 
longer than 30 minutes. This pre-clearance period may occur during any 
vessel activity. If any marine mammal (including delphinids) is 
observed within or approaching the 100 m EZ during the 30 minute pre-
clearance period, ramp-up may not begin until the animal(s) has been 
observed exiting the EZ or until an additional time period has elapsed 
with no further sightings (i.e., 15 minutes for small odontocetes and 
30 minutes for all other species).
    (iv) During ramp-up, PSOs shall monitor the 100 m EZ and 200 m 
buffer zone. Ramp-up may not be initiated if any marine mammal 
(including delphinids) is observed within or approaching the 100 m EZ. 
If a marine mammal is observed within or approaching the 100 m EZ 
during ramp-up, a shutdown shall be implemented as though the full 
array were operational. Ramp-up may not begin again until the animal(s) 
has been observed exiting the 100 m EZ or until an additional time 
period has elapsed with no further sightings (i.e., 15 minutes for 
small odontocetes and 30 minutes for mysticetes and large odontocetes 
including sperm, pygmy sperm, and beaked whales).
    (v) If the airgun array has been shut down for reasons other than 
mitigation (e.g., mechanical difficulty) for a period of less than 30 
minutes, it may be activated again without ramp-up if PSOs have 
maintained constant visual observation and no visual detections of any 
marine mammal have occurred within the buffer zone.
    (vi) Ramp-up at night and at times of poor visibility shall only 
occur where operational planning cannot reasonably avoid such 
circumstances. Ramp-up may occur at night and during poor visibility if 
the 100 m EZ and 200 m buffer zone have been continually monitored by 
visual PSOs for 30 minutes prior to ramp-up with no marine mammal 
detections.
    (vii) The vessel operator must notify a designated PSO of the 
planned start of ramp-upA designated PSO must be notified again 
immediately prior to initiating ramp-up procedures and the operator 
must receive confirmation from the PSO to proceed.
    (f) Shutdown requirements--An exclusion zone of 100 m shall be 
established and monitored by PSOs. If a marine mammal is observed 
within, entering, or approaching the 100 m exclusion zone all airguns 
shall be shut down.
    (i) Any PSO on duty has the authority to call for shutdown of the 
airgun array. When there is certainty regarding the need for mitigation 
action on the basis of visual detection, the relevant PSO(s) must call 
for such action immediately.
    (ii) The operator must establish and maintain clear lines of 
communication directly between PSOs on duty and crew controlling the 
airgun array to ensure that shutdown commands are conveyed swiftly 
while allowing PSOs to maintain watch.
    (iii) When a shutdown is called for by a PSO, the shutdown must 
occur and any dispute resolved only following shutdown.
    (iv) The shutdown requirement is waived for dolphins of the 
following genera: Tursiops, Stenella, Delphinus, Lagenorhynchus and 
Lissodelphis. The shutdown waiver only applies if animals are 
traveling, including approaching the vessel. If animals are stationary 
and the vessel approaches the animals, the shutdown requirement 
applies. If there is uncertainty regarding identification (i.e., 
whether the observed animal(s) belongs to the group described above) or 
whether the animals are traveling, shutdown must be implemented.
    (v) Upon implementation of a shutdown, the source may be 
reactivated under the conditions described at 4(e)(vi). Where there is 
no relevant zone (e.g., shutdown due to observation of a calf), a 30-
minute clearance period must be observed following the last observation 
of the animal(s).
    (vi) Shutdown of the array is required upon observation of a whale 
(i.e., sperm whale or any baleen whale) with calf, with ``calf'' 
defined as an animal less than two-thirds the body size of an adult 
observed to be in close association with an adult, at any distance.
    (vii) Shutdown of the array is required upon observation of an 
aggregation (i.e., six or more animals) of large whales of any species 
(i.e., sperm whale or any baleen whale) that does not appear to be 
traveling (e.g., feeding, socializing, etc.) at any distance.
    (viii) Shutdown of the array is required upon observation of a 
killer whale at any distance.
    (g) Vessel Strike Avoidance--Vessel operator and crew must maintain 
a vigilant watch for all marine mammals and slow down or stop the 
vessel or alter course, as appropriate, to avoid striking any marine 
mammal, unless such action represents a human safety concern. A visual 
observer aboard the vessel must monitor a vessel strike avoidance zone 
around the vessel according to the parameters stated below. Visual 
observers monitoring the vessel strike avoidance zone can be either 
third-party observers or crew members, but crew members responsible for 
these duties must be provided sufficient training to distinguish marine 
mammals from other phenomena.
    (i) The vessel must maintain a minimum separation distance of 100 m 
from large whales, unless such action represents a human safety 
concern. The following avoidance measures must be taken if a large 
whale is within 100 m of the vessel:
    (A) The vessel must reduce speed and shift the engine to neutral, 
when feasible, and must not engage the engines until the whale has 
moved outside of the vessel's path and the minimum separation distance 
has been established unless such action represents a human safety 
concern.
    (B) If the vessel is stationary, the vessel must not engage engines 
until the whale(s) has moved out of the vessel's path and beyond 100 m 
unless such action represents a human safety concern.
    (ii) The vessel must maintain a minimum separation distance of 50 m 
from all other marine mammals, with an exception made for animals 
described in 4(e)(iv) that approach the vessel. If an animal is 
encountered during transit, the vessel shall attempt to remain

[[Page 39306]]

parallel to the animal's course, avoiding excessive speed or abrupt 
changes in course unless such action represents a human safety concern.
    (iii) Vessel speeds must be reduced to 10 knots or less when 
mother/calf pairs, pods, or large assemblages of cetaceans are observed 
near the vessel unless such action represents a human safety concern.
    (h) Miscellaneous Protocols.
    (i) The airgun array must be deactivated when not acquiring data or 
preparing to acquire data, except as necessary for testing. Unnecessary 
use of the acoustic source shall be avoided. Operational capacity of 90 
in\3\ (not including redundant backup airguns) must not be exceeded 
during the survey, except where unavoidable for source testing and 
calibration purposes. All occasions where activated source volume 
exceeds notified operational capacity must be noticed to the PSO(s) on 
duty and fully documented. The lead PSO must be granted access to 
relevant instrumentation documenting acoustic source power and/or 
operational volume.
    (ii) Testing of the acoustic source involving all elements requires 
normal mitigation protocols (e.g., ramp-up). Testing limited to 
individual source elements or strings does not require ramp-up but does 
require pre-clearance.
    5. Monitoring Requirements.
    The holder of this Authorization is required to conduct marine 
mammal monitoring during survey activity. Monitoring shall be conducted 
in accordance with the following requirements:
    (a) The operator must provide a night-vision device suited for the 
marine environment for use during nighttime ramp-up pre-clearance, at 
the discretion of the PSOs. At minimum, the device should feature 
automatic brightness and gain control, bright light protection, 
infrared illumination, and optics suited for low-light situations.
    (b) PSOs must also be equipped with reticle binoculars (e.g., 7 x 
50) of appropriate quality (i.e., Fujinon or equivalent), GPS, digital 
single-lens reflex camera of appropriate quality (i.e., Canon or 
equivalent), compass, and any other tools necessary to adequately 
perform necessary tasks, including accurate determination of distance 
and bearing to observed marine mammals.
    (c) PSO Qualifications
    (i) PSOs must have successfully completed relevant training, 
including completion of all required coursework and passing a written 
and/or oral examination developed for the training program.
    (ii) PSOs must have successfully attained a bachelor's degree from 
an accredited college or university with a major in one of the natural 
sciences and a minimum of 30 semester hours or equivalent in the 
biological sciences and at least one undergraduate course in math or 
statistics. The educational requirements may be waived if the PSO has 
acquired the relevant skills through alternate experience. Requests for 
such a waiver must include written justification. 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 
marine mammal surveys; or (3) previous work experience as a PSO; the 
PSO should demonstrate good standing and consistently good performance 
of PSO duties.
    (d) Data Collection--PSOs must use standardized data 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 to resume survey. If required mitigation was not 
implemented, PSOs should submit a description of the circumstances. We 
require that, at a minimum, the following information be reported:
    (i) PSO names and affiliations.
    (ii) Dates of departures and returns to port with port name.
    (iii) Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort.
    (iv) Vessel location (latitude/longitude) when survey effort begins 
and ends; vessel location at beginning and end of visual PSO duty 
shifts.
    (v) Vessel heading and speed at beginning and end of visual PSO 
duty shifts and upon any line change.
    (vi) Environmental conditions while on visual survey (at beginning 
and end of PSO shift and whenever conditions change significantly), 
including wind speed and direction, Beaufort sea state, Beaufort wind 
force, swell height, weather conditions, cloud cover, sun glare, and 
overall visibility to the horizon.
    (vii) Factors that may be contributing to impaired observations 
during each PSO shift change or as needed as environmental conditions 
change (e.g., vessel traffic, equipment malfunctions).
    (viii) 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-ramp-up survey, ramp-up, shutdown, testing, shooting, ramp-
up completion, end of operations, streamers, etc.).
    (ix) If a marine mammal is sighted, the following information 
should be recorded:
    (A) Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
    (B) PSO who sighted the animal;
    (C) Time of sighting;
    (D) Vessel location at time of sighting;
    (E) Water depth;
    (F) Direction of vessel's travel (compass direction);
    (G) Direction of animal's travel relative to the vessel;
    (H) Pace of the animal;
    (I) Estimated distance to the animal and its heading relative to 
vessel at initial sighting;
    (J) Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified); also note the composition 
of the group if there is a mix of species;
    (K) Estimated number of animals (high/low/best);
    (L) Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
    (M) 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);
    (N) Detailed behavior observations (e.g., number of blows, number 
of surfaces, breaching, spyhopping, diving, feeding, traveling; as 
explicit and detailed as possible; note any observed changes in 
behavior);
    (O) Animal's closest point of approach (CPA) and/or closest 
distance from the center point of the acoustic source;
    (P) Platform activity at time of sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other); and
    (Q) Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up, speed or course alteration, 
etc.) and time and location of the action.
    6. Reporting.
    (a) SIO shall submit a draft comprehensive report on all activities 
and monitoring results within 90 days of the completion of the survey 
or

[[Page 39307]]

expiration of the IHA, whichever comes sooner. The report must describe 
all activities conducted and sightings of marine mammals near the 
activities, must provide full documentation of methods, results, and 
interpretation pertaining to all monitoring, and must summarize the 
dates and locations of survey operations and all marine mammal 
sightings (dates, times, locations, activities, associated survey 
activities). Geospatial data regarding locations where the acoustic 
source was used must be provided as an ESRI shapefile with all 
necessary files and appropriate metadata. In addition to the report, 
all raw observational data shall be made available to NMFS. The report 
must summarize the data collected as required under condition 5(d) of 
this IHA. The draft report must be accompanied by a certification from 
the lead PSO as to the accuracy of the report, and the lead PSO may 
submit directly to NMFS a statement concerning implementation and 
effectiveness of the required mitigation and monitoring. A final report 
must be submitted within 30 days following resolution of any comments 
from NMFS on the draft report.
    (b) Reporting injured or dead marine mammals:
    (i) In the event that the specified activity clearly causes the 
take of a marine mammal in a manner not prohibited by this IHA (if 
issued), such as serious injury or mortality, SIO shall immediately 
cease the specified activities and immediately report the incident to 
NMFS. The report must include the following information:
    (A) Time, date, and location (latitude/longitude) of the incident;
    (B) Vessel's speed during and leading up to the incident;
    (C) Description of the incident;
    (D) Status of all sound source use in the 24 hours preceding the 
incident;
    (E) Water depth;
    (F) Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, and visibility);
    (G) Description of all marine mammal observations in the 24 hours 
preceding the incident;
    (H) Species identification or description of the animal(s) 
involved;
    (I) Fate of the animal(s); and
    (J) Photographs or video footage of the animal(s).
    Activities shall not resume until NMFS is able to review the 
circumstances of the prohibited take. NMFS will work with SIO to 
determine what measures are necessary to minimize the likelihood of 
further prohibited take and ensure MMPA compliance. SIO may not resume 
their activities until notified by NMFS.
    (ii) In the event that SIO discovers an injured or dead marine 
mammal, and the lead observer determines that the cause of the injury 
or death is unknown and the death is relatively recent (e.g., in less 
than a moderate state of decomposition), SIO shall immediately report 
the incident to NMFS. The report must include the same information 
identified in condition 6(b)(i) of this IHA. Activities may continue 
while NMFS reviews the circumstances of the incident. NMFS will work 
with SIO to determine whether additional mitigation measures or 
modifications to the activities are appropriate.
    (iii) In the event that SIO discovers an injured or dead marine 
mammal, and the lead observer determines that the injury or death is 
not associated with or related to the specified activities (e.g., 
previously wounded animal, carcass with moderate to advanced 
decomposition, or scavenger damage), SIO shall report the incident to 
NMFS within 24 hours of the discovery. SIO shall provide photographs or 
video footage or other documentation of the sighting to NMFS.
    7. This Authorization may be modified, suspended or withdrawn if 
the holder fails to abide by the conditions prescribed herein, or if 
NMFS determines the authorized taking is having more than a negligible 
impact on the species or stock of affected marine mammals.

Request for Public Comments

    We request comment on our analyses, the draft authorization, and 
any other aspect of this Notice of Proposed IHA for the proposed 
seismic survey by SIO. Please include with your comments any supporting 
data or literature citations to help inform our final decision on the 
request for MMPA authorization.

    Dated: August 11, 2017.
Donna Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2017-17378 Filed 8-16-17; 8:45 am]
 BILLING CODE 3510-22-P