[Federal Register Volume 83, Number 105 (Thursday, May 31, 2018)]
[Notices]
[Pages 25268-25300]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-11629]



[[Page 25267]]

Vol. 83

Thursday,

No. 105

May 31, 2018

Part III





Department of Commerce





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National Oceanic and Atmospheric Administration





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

  Federal Register / Vol. 83 , No. 105 / Thursday, May 31, 2018 / 
Notices  

[[Page 25268]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XG170


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Marine Geophysical Survey in the 
Northwest Atlantic 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 United States Geological 
Survey (USGS) for authorization to take marine mammals incidental to a 
marine geophysical survey in the northwest Atlantic 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 authorizations, and agency responses 
will be summarized in the final notice of our decision.

DATES: Comments and information must be received no later than July 2, 
2018.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Physical comments should be sent to 
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments 
should be sent to [email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments received electronically, including 
all attachments, must not exceed a 25-megabyte file size. Attachments 
to electronic comments will be accepted in Microsoft Word or Excel or 
Adobe PDF file formats only. All comments received are a part of the 
public record and will generally be posted online at 
www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities 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: Jonathan Molineaux, Office of 
Protected Resources, NMFS, (301) 427-8401. Electronic copies of the 
application and supporting documents, as well as a list of the 
references cited in this document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-research-and-other-activities. 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. 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, 2018, NMFS received a request from USGS for an IHA to 
take marine mammals incidental to a marine geophysical survey in the 
northwest Atlantic Ocean. On April 11, 2018, we deemed USGS's 
application for authorization to be adequate and complete. USGS's 
request is for take a small number of 29 species of marine mammals by 
Level B harassment only. Neither USGS nor NMFS expects serious injury 
or 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

    The USGS intends to conduct a seismic survey aboard the R/V Hugh R. 
Sharp, a University National Oceanographic Laboratory (UNOLS) Federal 
fleet vessel that is owned and operated by the University of Delaware, 
during a cruise up to 22 days long on the northern U.S. Atlantic margin 
in August 2018. The program is named MATRIX, for ``Mid-Atlantic 
Resource Imaging Experiment.'' The seismic survey will take place in 
water depths ranging from ~100 meters (m) to 3,500 m, entirely within 
the U.S. Exclusive Economic Zone (EEZ), and acquire ~6 dip lines 
(roughly perpendicular to the orientation of the shelf-break) and ~3 
strike lines (roughly parallel to the shelf-break) between about 35 
nautical miles (nmi) south of Hudson Canyon on the north and Cape 
Hatteras on the south. In addition, multichannel seismic

[[Page 25269]]

(MCS) data will be acquired along some linking/transit/interseismic 
lines between the main survey lines. Total data acquisition could be up 
to ~2,400 kilometers (km) of trackline. Exemplary seismic lines for the 
program are shown in Figure 1. Some deviation in actual tracklines and 
timing could be necessary for reasons such as science drivers, poor 
data quality, inclement weather, or mechanical issues with the research 
vessel and/or equipment.
[GRAPHIC] [TIFF OMITTED] TN31MY18.000

    The purpose of the proposed MATRIX survey is to collect data to 
constrain the lateral and vertical distribution of gas hydrates and 
shallow natural gas in marine sediments relative to seafloor gas seeps, 
slope failures, and geological and erosional features.

Dates and Duration

    The seismic survey's airgun operations are scheduled to occur for 
up to 19 days during a cruise that may be as long as 22 days, departing 
port on August 8, 2018. Some minor deviation from these dates is 
possible, depending on logistics and especially weather.

Specific Geographic Region

    The survey is bound within the region ~34.75[deg] N-40[deg] N, ~71-
75[deg] W in the northwest Atlantic Ocean (See Figure 1), with the 
closest approach to the U.S. coastline at 70 km (North Carolina) to 130 
km (New Jersey). The survey area starts 35 nmi south of Hudson Canyon 
on the north and is bound by Cape Hatteras on the south, the nominal 
shelf break (~100 m water depth) on the west, and the ~3,500 m 
bathymetric contour on the east.

[[Page 25270]]

Detailed Description of Specific Activity

    The procedures that will be used for the seismic surveys would be 
similar to those used during previous research seismic surveys funded 
by the National Science Foundation (NSF) or conducted by the USGS and 
would utilize a conventional seismic methodology. The survey will 
involve only one source vessel, the R/V Hugh R. Sharp. The source 
vessel will deploy two to four low-energy Generator-Injector (GI) 
airguns (each with a discharge volume of 105 cubic inches (in\3\)) as 
an energy source. The GI guns could sometimes be fired in a mode that 
gives them a discharge volume of 210 in\3\ each, but only at water 
depths greater than 1,000 m (See description of Optimal Survey below 
for more details). A hydrophone streamer 750- to 1,300-m-long and 
consisting of up to 160 channels will be continuously towed to receive 
the seismic signals. In addition, up to 90 disposable sonobuoy 
receivers will be deployed at water depths greater than 1,000 m to 
provide velocity control and possibly wide-angle reflections along the 
highest priority transects. Below we provide a description of each of 
the airgun modes during the survey.
    The Optimal Survey (GG mode) (See Table 1) for the Proposed Action 
would acquire the portion of the solid lines in Figure 1 at water 
depths greater than 1,000 m using the GI-guns in ``GG'' mode. In this 
mode, the four GI guns would produce a total of 840 in\3\ of air and 
sonobuoys would be deployed to passively record data at long distances. 
When shooting to sonobuoys while in GG mode, the GI guns will be 
operated with both chambers releasing air simultaneously (i.e., 
``generator-generator'' or ``GG'' mode). The rest of the survey, 
including the portion shallower than 1,000 m water depth on the 
uppermost slope and the interseismic linking lines (dashed lines in 
Figure 1), would be acquired with four GI guns operated in normal mode 
(also called GI mode), producing a total of 420 in\3\ of air.
    The Base Survey (GI mode) (See Table 1) assumes that all of the 
solid lines in Figure 1, as well as all of the interseismic connecting 
lines, would be acquired using four GI guns operating in normal mode 
(GI mode), producing a total air volume of 420 in\3\. Only a maximum of 
half of the interseismic linking lines (dashed lines in Figure 1) would 
be acquired. These lines are longer and geometrically more complex at 
the deepwater side than near the shelf-break.

             Table 1--General Characteristics of Exemplary Survey Scenarios for the Proposed Action
----------------------------------------------------------------------------------------------------------------
                                         GI mode (4 x 105 in\3\)                  GG mode (4 x 210 in\3\)
                                --------------------------------------------------------------------------------
                                                            Track line                              Track line
                                   Depth and line type     distance (km)    Depth and line type    distance (km)
----------------------------------------------------------------------------------------------------------------
Optimal Survey.................  100-1,000 m water depth            ~750  Greater than 1,000 m            ~1,600
                                  on exemplary lines and                   on exemplary lines.
                                  50% of interseismic,
                                  linking lines.
Base Survey....................  Exemplary lines plus              2,350
                                  50% of interseismic,
                                  linking lines.
----------------------------------------------------------------------------------------------------------------

    During the cruise, the USGS would continuously use an echosounder 
(EK60/EK80) with 38 kHz transducer at water depths less than ~1,800 m 
to locate water column anomalies associated with seafloor seeps 
emitting gas bubbles. The 38 kHz transducer would be mounted in the R/V 
Sharp's retractable keel and would typically ping 0.5 to 2 Hz with 
pings of 0.256 to 1.024 millisecond (m/s) duration. The returned 
signals would be detected on an EK60 or EK80 (broadband) transceiver. 
Based on past USGS experience with this instrument, it is unlikely to 
acquire useful data at water depths greater than 1,800 m, although it 
could be used in passive mode at these depths to record broadband 
ambient signals in the water column.

Airgun Array Description

    The R/V Hugh R. Sharp will tow two or four 105-in\3\ Sercel GI 
airguns at a time as the primary energy source following exemplary 
survey lines and transit/linking/interseismic lines between the primary 
exemplary lines. Seismic pulses for the GI guns will be emitted at 
intervals of ~12 s. At speeds of ~7.4 km/h (4 knots (kn)), the shot 
intervals correspond to a spacing of ~25 m.
    In standard GI mode, the generator chamber of each GI airgun is the 
primary source, the one responsible for introducing the sound pulse 
into the ocean, is 105 in\3\. The 105 in\3\ injector chamber injects 
air into the previously-generated bubble to reduce bubble 
reverberations and does not introduce more sound into the water. In GG 
mode, each gun simultaneously releases an air volume of 105 in\3\ + 105 
in\3\ = 210 in\3\. On the proposed survey, four GI guns will be 
operated either in base mode (4 x 105 in\3\) or GG mode (4 x 210 in\3\) 
as long as compressors are functioning correctly. If compressors are 
not functioning properly, a backup mode consisting of two GI guns will 
be used. The text below describes the three preferred modes of 
operation.
    The Base Configuration, Configuration 1, will use 4 GI guns and 
generate 420 in\3\ total volume, as shown in Figure 2 of the IHA 
Application. Airguns will be towed at 3 m water depth, two on each side 
of the stern, with 8.6 m lateral (athwartships) separation between the 
pairs of guns and 2 m front-to-back separation between the guns on each 
stern tow line.
    The GG Configuration, Configuration 2, will use four GI guns and 
generate 840 in\3\ total volume, as shown in Figure 3 of the IHA 
application. In this configuration, the airguns will be fired in GG 
mode, as described above. Airguns will be towed at 3 m water depth, two 
on each side of the stern, with 8.6 m lateral (athwartships) separation 
between the pairs of airguns and 2 m front-to-back separation between 
the airguns on each stern tow line. The GG configuration would be used 
only at greater than 1000 m water depth and on specific exemplary lines 
on which sonobuoy data are being collected.
    The Backup Configuration (Configuration 3) is two GI airguns 
producing 210 in\3\ total volume. If a compressor were offline, this 
lowest-energy configuration would be used to sustain data acquisition. 
Airguns will be towed at 3 m water depth of the port towpoint on the 
stern, with 2 m front-to-back separation between the guns.
    As the GI airguns are towed along the survey line, the towed 
hydrophone array receives the reflected signals and

[[Page 25271]]

transfers the data to the on-board processing system. Given the short 
streamer length behind the vessel (1,300 m), the turning rate of the 
vessel while the gear is deployed is much higher than the limit of five 
degrees per minute for a seismic vessel towing a streamer of more 
typical length (e.g., 6 km or more). Thus, the maneuverability of the 
vessel is not strongly limited during operations.

                                        Table 2--GI Airgun Specifications
----------------------------------------------------------------------------------------------------------------
 
----------------------------------------------------------------------------------------------------------------
Energy Source...........................................................  Two (backup configuration) to four
                                                                           (base and GG configuration) GI
                                                                           airguns of 105 in\3\ each.
Tow depth of energy source..............................................  3 m.
Air discharge volume....................................................  Total volume ~210 in\3\ (backup
                                                                           configuration, Appendix A) to 840
                                                                           in\3\ (limited use GG configuration
                                                                           at greater than 1,000 m).
Back-to-front separation of pairs of guns...............................  2 m.
Side-to-side separation of pairs of guns................................  8.6 m.
Dominant frequency components...........................................  0-188 Hertz.
Shot interval...........................................................  9.72 seconds (2 m airgun separation
                                                                           survey) and 12.15 seconds (8 m airgun
                                                                           separation survey).
----------------------------------------------------------------------------------------------------------------

    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see ``Proposed 
Mitigation'' and ``Proposed Monitoring and Reporting'').

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS' Stock Assessment Reports (SAR; www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region), and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS' 
website (www.fisheries.noaa.gov/find-species).
    Table 3 lists all species with expected potential for occurrence in 
the northwest Atlantic 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. Atlantic SARs (Hayes et al., 2017). All values presented in 
Table 3 are the most recent available at the time of publication and 
are available in the draft 2017 SARs (Hayes et al., 2017) (available 
online at: www.nmfs.noaa.gov/pr/sars/draft.htm), and Roberts et. al. 
(2016).

                                              Table 3--Marine Mammals That Could Occur in the Project Area
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                                                                                            NMFS stock
                                                                            ESA/MMPA      abundance (CV,       Predicted
          Common name              Scientific name          Stock           status;     Nmin, most recent    abundance (CV)        PBR       Annual M/SI
                                                                         strategic (Y/  abundance survey)         \5\                            \3\
                                                                             N) \1\            \2\
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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                                                                    Family Balaenidae
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North Atlantic right whale.....  Eubalaena           Western North       E/D; Y         458 (n/a; 455; n/  334 (0.25).......  1.4.........  36
                                  glacialis.          Atlantic (WNA).                    a).
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                                                            Family Balaenopteridae (rorquals)
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Humpback whale.................  Megaptera           Gulf of Maine.....  -; N           335 (.42; 239;     1,637 (0.07).....  3.7.........  8.5
                                  novaeangliae                                           2012).
                                  novaeangliae.
Minke whale....................  Balaenoptera        Canadian East       -; N           2,591 (0.81;       2,112 (0.05).....  14..........  9
                                  acutorostrata       Coast.                             1,425; 2011).
                                  acutorostrata.
Bryde's whale..................  B. edeni brydei...  None defined \4\..  -; n/a         n/a..............  7 (0.58).........  n/a.........  n/a.
Sei whale......................  B. borealis         Nova Scotia.......  E/D; Y         357 (0.52; 236;    98 (0.25)........  0.5.........  0.8
                                  borealis.                                              2011).
Fin whale......................  B. physalus         WNA...............  E/D; Y         1,618 (0.33;       4,633 (0.08).....  2.5.........  2.65
                                  physalus.                                              1,234; 2011).
Blue whale.....................  B. musculus         WNA...............  E/D; Y         Unknown (n/a;      11 (0.41)........  0.9.........  Unk.
                                  musculus.                                              440; n/a).
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                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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                                                                   Family Physeteridae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale....................  Physeter            North Atlantic....  E/D; Y         2,288 (0.28;       5,353 (0.12).....  3.6.........  0.8
                                  macrocephalus.                                         1,815; 2011).
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                                                                     Family Kogiidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pygmy sperm whale..............  Kogia breviceps...  WNA...............  -; N           3,785 (0.47;       678 (0.23).......  21..........  3.5
                                                                                         2,598; 2011).

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Dwarf sperm whale..............  K. sima...........  WNA...............  -; N
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                                                            Family Ziphiidae (beaked whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cuvier's beaked whale..........  Ziphius             WNA...............  -; N           6,532 (0.32;       14,491 (0.17)....  50..........  0.4
                                  cavirostris.                                           5,021; 2011).
Gervais beaked whale...........  Mesoplodon          WNA...............  -; N           7,092 (0.54;                          46..........  0.2
                                  europaeus.                                             4,632; 2011).
Blainville's beaked whale......  M. densirostris...  WNA...............  -; N
Sowerby's beaked whale.........  M. bidens.........  WNA...............  -; N
True's beaked whale............  M. mirus..........  WNA...............  -; N
Northern bottlenose whale......  Hyperoodon          WNA...............  -; N           Unknown..........  90 (0.63)........  Undet.......  0
                                  ampullatus.
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                                                                   Family Delphinidae
--------------------------------------------------------------------------------------------------------------------------------------------------------
Rough-toothed dolphin..........  Steno bredanensis.  WNA...............  -; N           271 (1.0; 134;     532 (0.36).......  1.3.........  0
                                                                                         2011).
Common bottlenose dolphin......  Tursiops truncatus  WNA Offshore......  -; N           77,532 (0.40;      97,476 (0.06)....  561.........  39.4
                                  truncatus.                                             56,053; 2011).
Clymene dolphin................  Stenella clymene..  WNA...............  -; N           Unknown..........  12,515 (0.56)....  Undet.......  0
Atlantic spotted dolphin.......  S. frontalis......  WNA...............  -; N           44,715 (0.43;      55,436 (0.32)....  316.........  0
                                                                                         31,610; 2011).
Pantropical spotted dolphin....  S. attenuata        WNA...............  -; N           3,333 (0.91;       4,436 (0.33).....  17..........  0
                                  attenuata.                                             1,733; 2011).
Spinner dolphin................  S. longirostris     WNA...............  -; N           Unknown..........  262 (0.93).......  Undet.......  0
                                  longirostris.
Striped dolphin................  S. coeruleoalba...  WNA...............  -; N           54,807 (0.3;       75,657 (0.21)....  428.........  0
                                                                                         42,804; 2011).
Short-beaked common dolphin....  Delphinus delphis   WNA...............  -; N           70,184 (0.28;      86,098 (0.12)....  557.........  437
                                  delphis.                                               55,690; 2011).
Fraser's dolphin...............  Lagenodelphis       WNA...............  -; N           Unknown..........  492 (0.76).......  Undet.......  0
                                  hosei.
Atlantic white-sided dolphin...  Lagenorhynchus      WNA...............  -; N           48,819 (0.61;      37,180 (0.07)....  304.........  57
                                  acutus.                                                30,403; 2011).
Risso's dolphin................  Grampus griseus...  WNA...............  -; N           18,250 (0.46;      7,732 (0.09).....  126.........  43.2
                                                                                         12,619; 2011).
Melon-headed whale.............  Peponocephala       WNA...............  -; N           Unknown..........  1,175 (0.50).....  Undet.......  0
                                  electra.
Pygmy killer whale.............  Feresa attenuata..  WNA...............  -; N           Unknown..........  N/A..............  Undet.......  0
False killer whale.............  Pseudorca           WNA...............  -; Y           442 (1.06; 212;    95 (0.84)........  2.1.........  Unk.
                                  crassidens.                                            2011).
Killer whale...................  Orcinus orca......  WNA...............  -; N           Unknown..........  11...............  Undet.......  0
Short-finned pilot whale.......  Globicephala        WNA...............  -; Y           21,515 (0.37;      18,977 (0.11)....  159.........  192
                                  macrorhynchus.                                         15,913; 2011).
Long-finned pilot whale........  G. melas melas....  WNA...............  -; Y           5,636 (0.63;                          35..........  38
                                                                                         3,464; 2011).
White-beaked dolphin...........  Lagenorhynchus      WNA...............  -; N           2,003 (0.94;       39 (0.42)........  10..........  0
                                  albirostris.                                           1,023; 2007).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                             Family Phocoenidae (porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Harbor porpoise................  Phocoena phocoena   Gulf of Maine/Bay   -; N           79,833 (0.32;      45,089 (0.12)....  706.........  307
                                  phocoena.           of Fundy.                          61,415; 2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: www.nmfs.noaa.gov/pr/sars/. CV is coefficient of variation; Nmin is the minimum estimate of
  stock abundance.
\3\ These values, found in NMFS' SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial
  fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated
  with estimated mortality due to commercial fisheries is presented in some cases.
\4\ Bryde's whales are occasionally reported off the southeastern U.S. and southern West Indies. NMFS defines and manages a stock of Bryde's whales
  believed to be resident in the northern Gulf of Mexico, but does not define a separate stock in the Atlantic Ocean.
\5\ Predicted mean abundance derived from Roberts et. al. (2016)
Note: Italicized species are not expected to be taken or proposed for authorization.

    All species that could potentially occur in the proposed survey 
areas are included in Table 3. However, density estimates in Roberts et 
al. (2016) present very low density estimates within the proposed 
action area during the month of August for north Atlantic right whale, 
harbor porpoise, minke whale, Bryde's whale, blue whale, and white-
beaked dolphin (See Table 6 of IHA Application). This, in combination 
with the short length of the cruise and low level airguns provide 
reasonable evidence that take authorization is not necessary, nor 
should they be authorized for these species. Species with expected take 
are discussed below.

Humpback Whale

    Humpback whales inhabit all major ocean basins from the equator to 
subpolar latitudes. They generally follow a predictable migratory 
pattern in both hemispheres, feeding during the summer in the higher 
latitudes (40 to 70 degrees latitude) and migrating to lower latitudes 
(10 to 30 degrees latitude) where calving and breeding take place in 
the winter (Perry et al., 1999). During the spring, summer, and fall, 
humpback whales in the North Atlantic Ocean feed over a range that 
includes the eastern coast of the United States, the Gulf of St. 
Lawrence, Newfoundland/Labrador, and western Greenland.
    Based on density modeling by Mannocci et al. (2017) for the western 
North Atlantic, higher densities are expected to occur north of 40[deg] 
N during the summer; very low densities are expected south of 40[deg] 
N, and the USGS proposed survey is entirely south of this latitude.
    Of the more than 43,000 global sightings of humpback whale 
individuals or groups dating back more than 50 years in the Ocean 
Biogeographic Information System (OBIS) database (2017), only 79 
occurred within a rectangular block containing the exemplary proposed 
USGS seismic survey lines. Of these, fourteen sightings occurred during 
July, August, or September, primarily on the continental shelf between 
north of Washington Canyon and the mouth of Delaware Bay (See Figure 6 
of IHA Application). Three of these sightings have been at or seaward 
of the shelf break, near the landward ends of the two northernmost 
exemplary USGS seismic lines. Humpback whales could

[[Page 25273]]

be encountered in the proposed project area during an August survey, 
but this would be an extremely rare occurrence.

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).
    Based on density modeling by Mannocci et al. (2017) for the western 
North Atlantic, higher densities are expected to occur north of 40[deg] 
N during the summer; very low densities are expected south of 40[deg] 
N, where the USGS surveys are entirely located.
    Of the more than 11,000 sightings of sei whale individuals or 
groups dating back more than 50 years in the OBIS database, only seven 
occurred within a rectangular block containing the exemplary proposed 
USGS seismic survey lines. Of these, only two sightings, comprising 
three individuals in total, occurred between in July, August, or 
September (See Figure 6 IHA Application). Sei whales could be 
encountered in the proposed project area during an August survey, but 
this would be an extremely rare occurrence.

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).
    Based on density modeling by Mannocci et al. (2017) for the western 
North Atlantic, higher densities are expected to occur north of 40[deg] 
N; very low densities are expected south of 40[deg] N; where the USGS 
surveys are entirely located. Of the more than 68,000 sightings of fin 
whale individuals or groups dating back more than 50 years in the OBIS 
database, 131 occurred within a rectangular block containing the 
exemplary proposed USGS seismic survey lines. Of these, 29 sightings, 
comprising 60 individuals in total, occurred during July, August, or 
September (See Figure 6 of IHA Application). Fin whales could be 
encountered during the proposed August surveys, particularly closer to 
the shelf edge and near the uppermost continental slope.

Sperm Whale

    Sperm whales are found throughout the world's oceans in deep waters 
between about 60[deg] N and 60[deg] S latitudes. Their distribution is 
dependent on their food source and suitable conditions for breeding, 
and varies with the sex and age composition of the group. They are 
generally distributed over large areas that have high secondary 
productivity and steep underwater topography, in waters at least 1,000 
m deep (Jaquet and Whitehead 1996; Whitehead 2009). Based on density 
modeling by Mannocci et al. (2017), sperm whale are expected to occur 
throughout the deeper offshore waters of the western North Atlantic.
    The survey slightly intersects with a core abundance area for sperm 
whales. This area is centered on a large, deepwater valley system that 
is fed by a complex series of canyons and gullies incising the slope 
between Hendrickson and Baltimore Canyons (NMFS 2017). In the OBIS 
database, 686 sperm whale sightings occur within a rectangular area 
encompassing the survey area, and 395 occurred during July through 
September. As shown in Figure 6 of the IHA Application, most of these 
sightings are seaward of the shelf-break in deepwater, overlapping the 
area of the Proposed Action. Thus, sperm whales are likely to be 
encountered in the proposed project area during August 2018.

Pygmy/Dwarf 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). Both Kogia species are sighted primarily along 
the continental shelf edge and slope and over deeper waters off the 
shelf (Hansen et al., 1994; Davis et al., 1998). Several studies have 
suggested that pygmy sperm whales live mostly beyond the continental 
shelf edge, whereas dwarf sperm whales tend to occur closer to shore, 
often over the continental shelf (Rice 1998; Wang et al., 2002; MacLeod 
et al., 2004). Barros et al. (1998), on the other hand, suggested that 
dwarf sperm whales could be more pelagic and dive deeper than pygmy 
sperm whales. It has also been suggested that the pygmy sperm whale is 
more temperate and the dwarf sperm whale more tropical, based at least 
partially on live sightings at sea from a large database from the 
eastern tropical Pacific (Wade and Gerrodette 1993). This idea is also 
supported by the distribution of strandings in South American waters 
(Mu[ntilde]oz-Hincapi[eacute] et al., 1998).
    Only four pygmy sperm whale sightings in the OBIS database occurred 
within the general area of the survey, and three of these were during 
the July through September period. Pygmy and dwarf sperm whales would 
likely be rare in the proposed project area.

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). It is mostly known from strandings and strands more 
commonly than any other beaked whale (Heyning 1989). Its inconspicuous 
blows, deep-diving behavior, and tendency to avoid vessels all help to 
explain the infrequent sightings (Barlow and Gisiner 2006).
    Of the usable records in the OBIS database, 155 sightings of 
Cuvier's beaked whales overlap with the survey area, and 76 of these 
were during the July to September period. Cuvier's beaked whales could 
be encountered in the proposed project area.

Mesoplodont Beaked Whales (Including True's, Gervais', Sowerby's, and 
Blainville's Beaked Whale)

    Mesoplodont beaked whales are distributed throughout deep waters 
and along the continental slopes of the North Atlantic Ocean. True's 
beaked whale is mainly oceanic and occurs in warm temperate waters of 
the North Atlantic and southern Indian oceans (Pitman 2009). Gervais' 
beaked whale is mainly oceanic and occurs in tropical and warmer 
temperate waters of the Atlantic Ocean (Jefferson et al., 2015). 
Sowerby's beaked whale occurs in cold temperate waters of the Atlantic 
from the Labrador Sea to the Norwegian Sea, and south to New England, 
the Azores, and Madeira (Mead 1989). Blainville's beaked whale is found 
in tropical and warm temperate waters of all oceans; it has the widest 
distribution throughout the world of all mesoplodont species

[[Page 25274]]

and appears to be relatively common (Pitman 2009).
    Records of Mesoplodont beaked whale observations in the proposed 
survey area are varied. There are two sightings of Trues beaked whale 
in the OBIS database which occured in the general survey area, but only 
one of these was during the summer season that overlaps the Proposed 
Action. As a result, True's beaked whale would likely be rare in the 
proposed project area. No OBIS sightings of the Gervais' beaked whale 
have occurred in the survey area. However, given the geographic and 
depth range of the species, Gervais' beaked whale could be encountered 
in the proposed project area.
    There are eleven OBIS database sightings of Sowerby's beaked whale 
in the polygon enclosing the larger area of the proposed surveys, and 
nine of these were during the summer months. Due to this, Sowerby's 
beaked whale could be encountered in the proposed project area. In 
addition, one sighting of Blainsvill occurred in the survey area during 
the summer months. Blainville's beaked whale could be encountered in 
the proposed project area.

Northern Bottlenose Whale

    Northern bottlenose whales are distributed in the North Atlantic 
from Nova Scotia to about 70[deg] N in the Davis Strait, along the east 
coast of Greenland to 77[deg] N and from England, Norway, Iceland and 
the Faroe Islands to the south coast of Svalbard. It is largely a deep-
water species and is very seldom found in waters less than 2,000 m deep 
(Mead, 1989; Whitehead and Hooker, 2012). Of the sightings in the OBIS 
database, one occurred within the survey area and none during July 
through September. Nonetheless, northern bottlenose whales could be 
encountered in the proposed project area.

Rough-Toothed Dolphin

    The rough-toothed dolphin occurs in tropical and subtropical 
waters, rarely ranging farther north than 40[deg] N (Jefferson et al., 
2015). It is considered a pelagic species, but it can also occur in 
shallow coastal waters (Jefferson et al., 2015). Nine sightings in the 
OBIS database occur within the survey area, and seven of these were 
doing the summer. Rough-toothed dolphins could occur in the proposed 
project area.

Common 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). Only the offshore 
ecotype is expected to occur in the proposed survey area. In the OBIS 
database, 1873 sightings of bottlenose dolphins occurred within a 
polygon enclosing the general survey area, and 776 are within the 
summer months. Common bottlenose dolphins are very likely to be 
encountered in the proposed project area.

Clymene Dolphin

    The Clymene dolphin only occurs in tropical and subtropical waters 
of the Atlantic Ocean (Jefferson et al., 2008). In the western 
Atlantic, it occurs from New Jersey to Florida, the Caribbean Sea, the 
Gulf of Mexico, and south to Venezuela and Brazil (W[uuml]rsig et al., 
2000; Fertl et al., 2003). It is generally sighted in deep waters 
beyond the shelf edge (Fertl et al., 2003). Based on the USGS analyses, 
23 sightings of the 140 that are usable in the OBIS database are within 
the overall rectangular area that encloses the surveys, and 14 of these 
are during the summer months.

Atlantic Spotted Dolphin

    The Atlantic spotted dolphin is distributed in tropical and warm 
temperate waters of the North Atlantic from Brazil to New England and 
to the coast of Africa (Jefferson et al., 2015). There are two forms of 
Atlantic spotted dolphin--a large, heavily spotted coastal form that is 
usually found in shelf waters, and a smaller and less-spotted offshore 
form that occurs in pelagic offshore waters and around oceanic islands 
(Jefferson et al., 2015). In the OBIS database, 125 sightings are in 
the general area of the surveys, and 58 were during the summer. 
Atlantic spotted dolphins would likely be encountered in the proposed 
project area.

Pantropical Spotted Dolphin

    The pantropical spotted dolphin is distributed worldwide in 
tropical and some sub-tropical oceans (Perrin et al., 1987; Perrin and 
Hohn 1994). In the Atlantic, it can occur from ~40[deg] N to 40[deg] S 
but is much more abundant in the lower latitudes (Jefferson et al., 
2015). Pantropical spotted dolphins are usually pelagic, although they 
occur close to shore where water near the coast is deep (Jefferson et 
al., 2015). Of over 4,200 usable sightings in the OBIS database, 48 
were in the polygon encompassing the entire survey area, and 29 of 
these were during the summer months. Pantropical spotted dolphins could 
be encountered in the proposed project area.

Spinner Dolphin

    The spinner dolphin is pantropical in distribution, with a range 
nearly identical to that of the pantropical spotted dolphin, including 
oceanic tropical and sub-tropical waters between 40[deg] N and 40[deg] 
S (Jefferson et al., 2008). The distribution of spinner dolphins in the 
Atlantic is poorly known, but they are thought to occur in deep waters 
along most of the U.S. coast; sightings off the northeast U.S. coast 
have occurred exclusively in offshore waters >2,000 m (Waring et al., 
2010). Within the OBIS database of over 2,000 usable sightings, the 
USGS found that none occurred in the survey area in any season. 
However, based on the abundance grids from Roberts et al. (2016), 
spinner dolphins could be encountered in the survey area in August 
2018. Note that spinner and Clymene dolphins are often considered 
together in analyses but were separated here due to the availability of 
density grids for each species.

Striped Dolphin

    Striped dolphins are found in tropical to warm-temperate waters 
throughout the world (Carretta et al., 2016a). 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 striped dolphin 
is typically found in waters outside the continental shelf and is often 
associated with convergence zones and areas of upwelling (Archer 2009). 
However, it has also been observed approaching shore where there is 
deep water close to the coast (Jefferson et al., 2015). Of over 15600 
sightings in the OBIS database, 183 were in the area of the survey, and 
95 of these were during the summer. Striped dolphins would likely be 
encountered in the proposed project area.

Short-Beaked Common Dolphin

    The short-beaked common dolphin is distributed in tropical to cool 
temperate waters of the Atlantic and the Pacific oceans from 60[deg] N 
to ~50[deg] S (Jefferson et al., 2015). It is common in coastal waters 
200-300 m deep (Evans 1994), but it can also occur thousands of 
kilometers offshore; the pelagic range in the North Atlantic extends 
south to ~35[deg] N (Jefferson et al., 2015). It appears

[[Page 25275]]

to have a preference for areas with upwelling and steep sea-floor 
relief (Doks[aelig]ter et al., 2008; Jefferson et al., 2015). Fewer 
than 0.1 percent of the nearly 43,000 of short-beaked common dolphins 
in the OBIS database occur in the general area of the survey, and only 
three were during the summer months. Short-beaked common dolphins could 
be encountered in the proposed project area.

Fraser's Dolphin

    Fraser's dolphin is a deepwater (>1,000 m) species that occurs in 
subtropical to tropical waters, nominally as far north as 30[deg] N. 
This species can dive to substantial water depths in search of prey. 
The dolphins often occur in large groups (100 or more). The OBIS 
database has fewer than 200 sightings of Fraser dolphins. Only three 
sightings were within the larger project area, and only two of those 
were during the summer months. Fraser's dolphins could be encountered 
within the survey area during the Proposed Action.

Atlantic White-Sided Dolphin

    White-sided dolphins are found in temperate and sub-polar waters of 
the North Atlantic, primarily in continental shelf waters to the 100-m 
depth contour. In the western North Atlantic the species inhabits 
waters from central West Greenland to North Carolina (about 35[deg] N) 
and perhaps as far east as 29[deg] W in the vicinity of the mid-
Atlantic Ridge (Evans 1987; Hamazaki 2002; Doksaeter et al., 2008; 
Waring et al., 2008). Based on density modeling by Mannocci et al. 
(2017) for the western North Atlantic, densities are highest north of 
40[deg] N, with densities gradually decreasing to the south. In the 
OBIS database, 28 sightings of the Atlantic white-sided dolphin occur 
in the general area of the survey, and nine of these are during the 
summer months. Atlantic white-sided dolphins could be encountered in 
the proposed project area.

Risso's Dolphin

    Risso's dolphins are found in tropical to warm-temperate waters 
(Carretta et al., 2016a). 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[deg] N and 60[deg] S where surface water temperatures 
are at least 10[deg]C (Kruse et al., 1999). Based on density modeling 
by Mannocci et al. (2017) for the western North Atlantic, higher 
densities are expected to occur north of 40[deg] N; very low densities 
are expected south of 40[deg] N. There were 471 sightings of Risso's 
dolphins in the general area of the project in the OBIS database, and 
238 of these were during the summer. Risso's dolphin is likely to be 
encountered in the proposed project area during August.

Melon-Headed Whale

    The melon-headed whale is a pantropical species usually occurring 
between 40[deg] N and 35[deg] S (Jefferson et al., 2008). Occasional 
occurrences in temperate waters are extralimital, likely associated 
with warm currents (Perryman et al., 1994; Jefferson et al., 2008). 
Melon-headed whales are oceanic and occur in offshore areas (Perryman 
et al., 1994), as well as around oceanic islands. Off the east coast of 
the United States, sightings have been made of two groups (20 and 80) 
of melon-headed whales off Cape Hatteras in waters 2,500 m deep during 
vessel surveys in 1999 and 2002 (NMFS 1999, 2002 in Waring et al., 
2010). The OBIS database contains more than 300 sightings records for 
the melon-headed whale, and none of these are within the survey area.
    The Roberts et al. (2015b) model density grid for the melon-headed 
whale has only two values for abundance: Zero in most of the U.S. EEZ 
and 0.240833 animals per 100 square kilometers (km\2\) in the rest of 
the modeled area. There are no melon-headed whales in waters shallower 
than 1,000 m in the model in the area of the Proposed Action, meaning 
that take calculations only capture potential animals in deeper waters. 
Melon-headed whales may be encountered during the seismic surveys, but 
they would likely be almost exclusively in deeper water and are more 
likely near the southern survey transects than the northern ones.

Killer Whale

    Killer whales have been observed in all oceans and seas of the 
world (Leatherwood and Dahlheim 1978). Killer whale distribution in the 
Western Atlantic extends from the Arctic ice edge to the West Indies. 
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). Killer whales have been sighted in shelf 
and offshore waters of Newfoundland and Labrador during June to 
September (DFO Sightings Database 2017; OBIS 2017).
    Killer whales are large and conspicuous, often traveling in close-
knit matrilineal groups of a few to tens of individuals (Dahlheim and 
Heyning 1999). Killer whales appear to prefer coastal areas but are 
also known to occur in deep water (Dahlheim and Heyning 1999). In over 
3,000 usable killer whale sightings in the OBIS database, only 0.1 
percent were within the larger rectangular area enclosing the survey, 
and none was during the summer months. Killer whales could be 
encountered within the proposed project area.

False Killer Whale

    The false killer whale is distributed worldwide throughout warm 
temperate and tropical oceans (Jefferson et al., 2008). This species is 
usually sighted in offshore waters but in some cases inhabits waters 
closer shore (e.g., Hawaii, Baird et al., 2013). While records from the 
U.S. western North Atlantic have been uncommon, the combination of 
sighting, stranding and bycatch records indicates that this species 
routinely occurs in the western North Atlantic. The pelagic range in 
the North Atlantic is usually southward of ~30[deg] N, but wanderers 
have been recorded as far north as Norway (Jefferson et al., 2015). Of 
more than 1,100 usable sightings recorded in the OBIS database, two 
occurred within the rectangle enclosing the survey area, and one of 
those was during the summer months. False killer whales could be 
encountered in the proposed project area.

Pygmy Killer Whale

    The pygmy killer whale is distributed worldwide in temperate to 
tropical waters (Caldwell and Caldwell, 1989; McAlpine, 2002). 
Sightings in the western North Atlantic occur in oceanic waters (Mullin 
and Fulling, 2003). Pygmy killer whales are usually found in deep water 
and rarely are found close to shore except where deepwater approaches 
the shore (Jefferson et al., 2015). Three sightings of pygmy killer 
whales are found in the OBIS database for the general area of the 
survey, and all of these occurred during the summer. Pygmy killer 
whales could occur in the survey area.

Short-Finned Pilot Whale

    Short-finned pilot whales are found in all oceans, primarily in 
tropical and warm-temperate waters (Carretta et al., 2016a). 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). Pilot whales are 
generally nomadic but may be resident in certain locations (Olson 
2009). There is some overlap of range with G. melas

[[Page 25276]]

in temperate waters (Jefferson et al., 2015). Water temperature appears 
to be the primary factor determining the relative distribution of these 
two species (Fullard et al., 2000). The short-finned pilot whale 
inhabits pelagic as well as nearshore waters (Olson 2009). Of over 
2,500 usable sightings in the OBIS database, 414 were within the 
rectangular area encompassing the survey lines, and 105 of these were 
during the summer months. Thus, short-finned pilot whales would likely 
be encountered in the proposed project area. Note that pilot whales are 
dealt with as an entire guild by Roberts et al. (2015), meaning that 
there are no specific model density grids applicable to short-finned 
pilot whales.

Long-Finned Pilot Whale

    Long-finned pilot whales occur in temperate and sub-polar zones 
(Jefferson et al., 2015) and can be found in inshore or offshore waters 
of the North Atlantic (Olson 2009). In the Northern Hemisphere, their 
range includes the U.S. east coast, Gulf of St. Lawrence, the Azores, 
Madeira, North Africa, western Mediterranean Sea, North Sea, Greenland 
and the Barents Sea. Despite this range, which would appear to overlap 
with that of the Proposed Action, over 9,000 records in the OBIS 
database yielded 51 that occurred in the rectangular box enclosing the 
larger survey area. Sixteen of these occurred during the summer months, 
mostly on the upper continental slope. The long-finned pilot whale 
could be encountered in the proposed study area. Note that pilot whales 
are dealt with as an entire guild by Roberts et al. (2015c), meaning 
that there are no specific model density grids applicable to short-
finned pilot whales.

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 
decibels (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 hertz (Hz) and 35 
kilohertz (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;
     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;
     Pinnipeds in water; Otariidae (eared seals): Generalized 
hearing is estimated to occur between 60 Hz and 39 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).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2016) for a review of available information. 
Twenty nine marine mammal species (all cetaceans) have the reasonable 
potential to co-occur with the proposed survey activities. Please refer 
to Table 3. Of the cetacean species that may be present, three are 
classified as low-frequency cetaceans (i.e., all mysticete species), 24 
are classified as mid-frequency cetaceans (i.e., all delphinid and 
ziphiid species and the sperm whale), and two are classified as high-
frequency cetaceans (i.e., Kogia spp.).

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

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

Description of Active Acoustic Sound Sources

    This section contains a brief technical background on sound, the 
characteristics of certain sound types, and on metrics used in this 
proposal inasmuch as the information is relevant to the specified 
activity and to a discussion of the potential effects of the specified 
activity on marine mammals found later in this document.
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in Hz or cycles per second. Wavelength is the distance 
between two peaks or corresponding points of a sound wave (length of 
one cycle). Higher frequency sounds have shorter wavelengths than lower 
frequency sounds, and typically attenuate (decrease) more rapidly, 
except in certain cases in shallower water. Amplitude is the height of 
the sound pressure wave or the ``loudness'' of a sound and is typically 
described using the relative unit of the dB. A sound pressure level 
(SPL) in dB is described as the ratio between a measured pressure and a 
reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)) and is a logarithmic unit that accounts for large variations 
in amplitude; therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. The source level (SL)

[[Page 25277]]

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). It should be noted that 
differences in the reference pressure, density, and sound velocity for 
water and air give the result that dB levels in water are 61.5 dB 
greater than the same absolute intensity in air.
    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 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; and
     Anthropogenic: Sources of ambient sound related to human 
activity include transportation (surface vessels), dredging and 
construction, oil and gas drilling and production, seismic surveys, 
sonar, explosions, and ocean acoustic studies. Vessel noise typically 
dominates the total ambient sound for frequencies between 20 and 300 
Hz. In general, the frequencies of anthropogenic sounds are below 1 kHz 
and, if higher frequency sound levels are created, they attenuate 
rapidly. Sound from identifiable anthropogenic sources other than the 
activity of interest (e.g., a passing vessel) is sometimes termed 
background sound, as opposed to ambient sound.
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
human activity) but also on the ability of sound to propagate through 
the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al., 1995). The result is that, 
depending on the source type and its intensity, sound from a given 
activity may be a negligible addition to the local environment or could 
form a distinctive signal that may affect marine mammals. Details of 
source types are described in the following text.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed (defined in the following). The distinction 
between these two sound types is important because they have differing 
potential to cause physical effects, particularly with regard to 
hearing (e.g., Ward, 1997 in Southall et al., 2007). Please see 
Southall et al. (2007) for an in-depth discussion of these concepts.
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or non-continuous (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems (such as 
those used by the U.S. Navy). The duration of such sounds, as received 
at a distance, can be greatly extended in a highly reverberant 
environment.

[[Page 25278]]

    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.
    In addition to airguns, the USGS would continuously use a fisheries 
echosounder (EK60/EK80) with 38 kHz transducer at water depths less 
than ~1,800 m from the R/V Hugh R. Sharp. Due to the lower source level 
of the EK60/EK80 relative to the R/V Hugh R. Sharp's airgun array, the 
sounds from the EK60/EK80 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 EK60/EK80 would already have been exposed to 
sounds from the airgun array, which are expected to propagate further 
in the water. As such, the EK60/EK80 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 EK60/EK80 further in this analysis.

Acoustic Impacts

    Potential Effects of Underwater Sound--Please refer to the 
information given previously (``Description of Active Acoustic Sound 
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 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 TS 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 
(SELcum) thresholds are 15 to 20 dB higher than TTS 
SELcum 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;

[[Page 25279]]

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 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

[[Page 25280]]

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 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

[[Page 25281]]

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; 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 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

[[Page 25282]]

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 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 kn. The chances of a lethal 
injury decline from approximately 80 percent at 15 kn to approximately 
20 percent at 8.6 kn. At speeds below 11.8 kn, the chances of lethal 
injury drop below 50 percent, while the probability asymptotically 
increases toward one hundred percent above 15 kn.
    The R/V Hugh R. Sharp would travel at a speed of ~7.4 km/h (4 kn) 
while towing seismic survey gear (LGL, 2018). At these speeds, 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

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traveling at low speed (5.5 kn) while conducting mapping surveys off 
the central California coast struck and killed a blue whale in 2009. 
The State of California determined that the whale had suddenly and 
unexpectedly surfaced beneath the hull, with the result that the 
propeller severed the whale's vertebrae, and that this was an 
unavoidable event. This strike represents the only such incident in 
approximately 540,000 hours of similar coastal mapping activity (p = 
1.9 x 10-6; 95% CI = 0-5.5 x 10-6; NMFS, 2013b). 
In addition, a research vessel reported a fatal strike in 2011 of a 
dolphin in the Atlantic, demonstrating that it is possible for strikes 
involving smaller cetaceans to occur. In that case, the incident report 
indicated that an animal apparently was struck by the vessel's 
propeller as it was intentionally swimming near the vessel. While 
indicative of the type of unusual events that cannot be ruled out, 
neither of these instances represents a circumstance that would be 
considered reasonably foreseeable or that would be considered 
preventable.
    Although the likelihood of the vessel striking a marine mammal is 
low, we require a robust ship strike avoidance protocol (see ``Proposed 
Mitigation''), which we believe eliminates any foreseeable risk of ship 
strike. 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 (22 
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 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-milimeter (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 ship crews 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

[[Page 25284]]

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 airgun 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 (22 days) and would occur over a very small area relative to the 
area available as marine mammal habitat in the Northwest Atlantic 
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 effects to 
their prey would be insignificant due to the limited spatial and 
temporal 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 ``small numbers'' and the negligible impact 
determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would be by Level B harassment only, in the form 
of disruption of behavioral patterns for individual marine mammals 
resulting from exposure to airguns. Based on the nature of the 
activity, the cryptic behavior and low density for kogia spp (the only 
high-frequency cetacean authorized for take) within the action areas, 
and the anticipated effectiveness of the mitigation measures (i.e., 
shutdown and a minimum vessel distance of 100 m from large whales--

[[Page 25285]]

discussed in detail below in the Proposed Mitigation section), Level A 
harassment is neither anticipated nor proposed to be authorized.
    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 proposed take estimate.

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 what the available science indicates 
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 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. USGS'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 (Technical Guidance, 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). 
As described above, USGS's proposed activity includes the use of 
intermittent and impulsive seismic sources. These thresholds are 
provided in Table 4.
    These thresholds are provided in the table 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: 
http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.

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

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds.
    The proposed survey would entail the use of a 4-airgun array with a 
total maximum discharge of 840 in\3\ for operations that occur at water 
depths greater than 1,000 m and 420 in\3\ for operations that occur at 
water depths of 1,000 m or less with at a tow depth of 3 m. The 
distances to the predicted isopleths corresponding to the threshold for 
Level B harassment (160 dB re 1 [mu]Pa) were calculated for both 
proposed array configurations based on results of modeling performed by 
LDEO's Nucleus Model. 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 (~600-1,100 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 Level B harassment isopleths for the two 
proposed configurations of the R/V

[[Page 25286]]

Hugh R. Sharp airgun array are shown in Table 5.

 Table 5--Modeled Radial Distances [m (km\2\)] From R/V Hugh R. Sharp's Airgun Array to Isopleths Corresponding
                                        to Level B Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                                                 Predicted RMS radii (m)
           Source and volume             Tow depth (m)    Water depth  -----------------------------------------
                                                              (m)                        160 dB
----------------------------------------------------------------------------------------------------------------
Base Configuration (Configuration 1):                3        >1,000 m  1,091 m (3.7 km\2\).\1\
 Four 105 in\3\ GI-guns.                ..............     100-1,000 m  1,637 m (8.42 km\2\).\2\
GG Configuration (Configuration 2):                  3        >1,000 m  1,244 m (4.86 km\2\).\1\
 Four 210 in\3\ GI-guns.                ..............     100-1,000 m  1,866 m (10.94k m\2\).\2\
----------------------------------------------------------------------------------------------------------------
\1\ Distance is based on L-DEO model results.
\2\ Distance is based on L-DEO model results with a 1.5x correction factor between deep and intermediate water
  depths.

    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 SELs obtained from LDEO model 
results down to a maximum water depth of 2,000 m (see Figures 4 and 5 
in the IHA application). LDEO's modeling methodology is described in 
greater detail in the IHA application (USGS, 2018) 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 4), 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 tools to help 
predict a simple isopleth that can be used in conjunction with marine 
mammal density or occurrence to facilitate the estimation of take 
numbers.
    The values for SELcum and peak SPL for the R/V Hugh R. 
Sharp 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 4-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.
    In order to more realistically incorporate the Technical Guidance's 
weighting functions over the seismic array's full acoustic band, 
unweighted spectrum data for the R/V Hugh R. Sharp'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 2.06 m/second and a shot 
interval of 12.15 seconds, potential radial distances to auditory 
injury zones were calculated for Peak SPLflat and 
SELcum thresholds, for both array configurations. Source 
level Inputs to the User Spreadsheet are shown in Table 6 (inputs to 
the user spreadsheet also included the source velocity and shot 
interval listed above). Outputs from the User Spreadsheet in the form 
of estimated distances to Level A harassment isopleths are shown in 
Table 7. 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 Appendix C of the 
IHA application.

[[Page 25287]]



                                     Table 6--Modeled Source Levels ** (dB) for the R/V Hugh R. Sharp's Airgun Array
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                 Configuration 1 * 4   Configuration 1 *   Configuration 2 *   Configuration 2 *   Configuration 3 *   Configuration 3 *
    Functional hearing group      x 105 cu\3\ SELcum  4 x 105 cu\3\ Peak     4 x 210 cu\3\    4 x 210 cu\3\ Peak     2 x 105 cu\3\    2 x 105 cu\3\ Peak
                                                            SPLflat             SELcum              SPLflat             SELcum              SPLflat
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low frequency cetaceans          214................  239...............  215...............  240...............  208...............  235
 (Lpk,flat: 219 dB; LE,LF,24h:
 183 dB).
Mid frequency cetaceans          214................  N/A...............  215...............  N/A...............  208...............  234
 (Lpk,flat: 230 dB; LE,MF,24h:
 185 dB).
High frequency cetaceans         214................  239...............  215...............  240...............  208...............  235
 (Lpk,flat: 202 dB; LE,HF,24h:
 155 dB).
--------------------------------------------------------------------------------------------------------------------------------------------------------
* All configurations have the following airgun specifications: 3 m tow depth; 2 m separation in the fore-aft direction; 8.6 m separation in the port
  (starboard direction).
** Source Levels were rounded to nearest whole number. See Appendix C of IHA Application for exact value.


       Table 7--Modeled Radial Distances [m(m2)] From R/V Hugh R. Sharp's Airgun Array to Isopleths Corresponding to Level A harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Configuration 1 4
                                 Configuration 1 4 x  x 105 cu\3\ 3m tow   Configuration 2 4   Configuration 2 4   Configuration 3 2   Configuration 3 2
    Functional hearing group       105 cu\3\ SELcum       depth, Peak     x 210 cu\3\ SELcum   x 210 cu\3\ Peak   x 105 cu\3\ SELcum   x 105 cu\3\ Peak
                                                            SPLflat                                 SPLflat                                 SPLflat
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low frequency cetaceans          31 m (3,019 m\2\)..  10.03 m (316 m\2\)  39.5 m (4,902       11.56 m (42 0       10.6 m (353 m\2\).  6.52 m (134 m\2\)
 (Lpk,flat: 219 dB; LE,LF,24h:                                             m\2\).              m\2\).
 183 dB).
Mid frequency cetaceans          0..................  0.................  0.................  0.................  0.................  1.58 m (8 m\2\)
 (Lpk,flat: 230 dB; LE,MF,24h:
 185 dB).
High frequency cetaceans         0..................  70.426 m (15,582    0.1 (.03 m\2\)....  80.50 m (20,358     0.................  42.32 m (5,627
 (Lpk,flat: 202 dB; LE,HF,24h:                         m\2\).                                  m\2\).                                  m\2\)
 155 dB).
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used, isopleths produced may be overestimates to some degree. 
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 all cetacean species, densities calculated by 
Roberts et al. (2016) were used. These represent the most comprehensive 
and recent density data available for cetacean species in the survey 
area. Roberts et al. (2016) retained 21,946 cetacean sightings for 
analysis, omitted 4,786 sightings, and modeled 25 individual species 
and 3 multi-species guilds. In order to procure density models for 
species, Roberts et al. (2016) used an approach known as density 
surface modeling, as seen in DoN (2007) and Roberts et al. (2016). This 
couples traditional distance sampling with multivariate regression 
modeling to produce density maps predicted from fine-scale 
environmental covariates (e.g., Becker et al., 2014).
    In addition to the density information provided by Roberts et al. 
(2016), best available data on average group sizes taken from sightings 
in the western North Atlantic were also used. This is discussed more in 
the section below.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. To estimate marine 
mammal exposures, the USGS used published, quantitative density models 
by Roberts et al. (2016) for the Survey Area, which is entirely within 
the U.S. EEZ. These models are provided at 10 km x 10 km resolution in 
ArcGIS compatible IMG grids on the Duke University cetacean density 
website (http://seamap.env.duke.edu/models/Duke-EC-GOM-2015). When 
available, the cetacean density models for Month 8 (August) were used. 
Otherwise, the generic annual density model was employed. Only a single 
density model is provided for the Kogia guild (dwarf and sperm pygmy 
whales), beaked whale guild (Blainville's, Cuvier's, Gervais', 
Sowerby's, and True's beaked whales), and for pilot whales.
    To determine takes, the USGS combined the Duke density grids with 
Level A and B zones (See Tables 5 and 7) arrayed on either side of each 
exemplary seismic line and linking/interseismic line. The Level B and 
Level A takes for each species in each 10 km x 10 km block of the IMG 
density grids were calculated based on the fractional area of each 
block intersected by the Level A and Level B zones for LF, MF, and HF 
cetaceans. Summing takes along all of the lines yields the total take 
for each species for the Proposed Action for the Base (Configuration 1) 
and Optimal (Configuration 2) surveys. The method also yields take for 
each survey line individually, allowing examination of those exemplary 
lines that will yield the largest or smallest take. No Level A takes 
were calculated while using this method.
    As indicated earlier, estimated numbers of individuals potentially 
exposed to sound above the Level B harassment threshold are based on 
the 160-dB re 1[mu]Pa (rms) criterion for all cetaceans. It is assumed 
that marine mammals exposed to airgun sounds that strong could change 
their behavior sufficiently to be considered taken by harassment. Table 
8 shows the estimates of the number of cetaceans that potentially could 
be exposed to >=160 dB re 1 [mu]Pa (rms) during the Proposed Action for 
the Base Survey and the Optimal Survey if no animals moved away from 
the survey vessel. The proposed takes in Table 8 represents 25 percent 
more than the number of takes calculated using the ArcGIS-based 
quantitative method devised by the USGS. This was used as a preventive 
measure to account for potential additional seismic operations that may

[[Page 25288]]

occur after repeat coverage of any areas where initial data quality is 
sub-standard.
    Also, as shown in Table 8, rough toothed dolphin, sei whale, and 
humpback whale calculated takes were increased to account for the 
average size of one group for each species. Takes for rare species of 
marine mammals in the action area were also increased to the average 
size of one group. Rare species that could be encountered and taken 
during the surveys are not presented in Table 8, but are presented in 
Table 9. These species were omitted from Table 8 due to their low 
reported densities in the action area (Roberts et al. 2016) resulting 
in low calculated incidents of potential exposures. As a result, NMFS 
relied on average group size data to propose the take of a single group 
of these species as a precautionary measure in case the survey 
encounters them. This is discussed further below Table 8.
    The calculated takes in Table 8 also assume that the proposed 
surveys would be completed. However, it is unlikely that the entire 
survey pattern (exemplary lines plus 50 percent of the interseismic, 
linking lines) would be completed given the limitations on ship time, 
likely logistical challenges (compressor and GI gun repairs), time 
spent on transits and refueling, and the historical problems with 
weather during August in the Northwest Atlantic. The USGS calculated 
timelines indicate that 25 days, including contingency, could be 
required to complete the full survey pattern. However, only 22 days or 
fewer would be scheduled for this USGS survey. The lines that are 
actually acquired would be dependent on weather, strength of the Gulf 
Stream (affects ability to tow the streamer in the appropriate 
geometry), and other considerations.

  Table 8--Calculated Incidents of Potential Exposure for Level B and Level A Harassment Based on Density Estimates From Roberts et al. (2016) and USGS
                                                                  GIS Take Methodology
                                                [As discussed, table omits rare species discussed below]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Base survey             Optimal survey       Max Level A  Max Level B
                                                 ----------------------------------------------------   take for     take for     Proposed
                                                                                                       optimal or   optimal or   take (all     Proposed
                     Species                                                                              base         base       Level B)    take as %
                                                    Level A      Level B      Level A      Level B      surveys      surveys        \6\       of pop.\1\
                                                                                                          +25%         +25%
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Low Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale..................................            0            0            0            0            0            0        \5\ 2         <0.1
Sei whale.......................................            0            1            0            1            0            1        \7\ 2         2.04
Fin whale.......................................            0            4            0            4            0            5            5          0.1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                 Mid-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale.....................................            0          119            0          128            0          160          160          2.9
Cuvier's beaked whale...........................            0       \2\ 94            0      \2\ 103            0      \2\ 128      \2\ 128         <0.1
True's beaked whale.............................            0  ...........            0  ...........            0  ...........  ...........  ...........
Gervais beaked whale............................            0  ...........            0  ...........            0  ...........  ...........  ...........
Sowerby's beaked whale..........................            0  ...........            0  ...........            0  ...........  ...........  ...........
Blainville's beaked whale.......................            0  ...........            0  ...........            0  ...........  ...........  ...........
Rough-toothed dolphin...........................            0            4            0            5            0            8       \3\ 10          1.9
Common bottlenose dolphin.......................            0          572            0          606            0          757          757          0.8
Pantropical spotted dolphin.....................            0           38            0           40            0           50           50          1.1
Atlantic spotted dolphin........................            0         1191            0         1278            0         1598         1598          2.9
Striped dolphin.................................            0         1086            0         1167            0         1458         1458          1.9
Short-beaked common dolphin.....................            0         1253            0         1296            0         1620         1620          1.9
Risso's dolphin.................................            0          181            0          189            0          236          236            3
Long-finned pilot whale.........................            0      \4\ 215            0      \4\ 231            0      \4\ 288      \4\ 288          1.5
Short-finned pilot whale........................            0  ...........  ...........  ...........            0  ...........  ...........  ...........
Clymene's dolphin...............................            0           91            0           97            0          121          121            1
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                High-Frequency Cetaceans
--------------------------------------------------------------------------------------------------------------------------------------------------------
Pygmy/dwarf sperm whale.........................            0            6            0            7            0            9            9          0.2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Based on mean abundance estimates from Roberts et al. (2016).
\2\ Values for density, proposed take number, and percentage of population proposed for authorization are for all beaked whales combined.
\3\ Based on one average group size for rough toothed dolphin (Jefferson 2015).
\4\ Values for density, proposed take number, and percentage of population proposed for authorization are for short-finned and long-finned pilot whales
  combined.
\4\ Based on one average group size for humpback whales (Waring 2008). Very small take requested because these species are very abundant, but the
  calculated take is zero based on the Duke density maps, which cannot capture all of the complexity in species distribution. Summer seasonal sightings
  compiled from the OBIS database (See Figure 6 of IHA Application) show that humpback whales have been seen in the northern part of the Proposed Action
  area during August.
\6\ Values are the same proposed take numbers shown in Table 9 below. Table 9 includes proposed take of rare species discussed below.
\7\ Based on one average group size for sei whale in the western Atlantic (NMFS 2017).

    Certain species potentially present in the proposed survey areas 
are expected to be encountered only extremely rarely, if at all. 
Although Roberts et al. (2016) provide density models for these species 
(with the exception of the pygmy killer whale), due to the small 
numbers of sightings that underlie these models' predictions we believe 
it appropriate to account for the small likelihood that these species 
would be encountered by assuming that one group of each of these 
species might be encountered once by a given survey. With the exception 
of the northern bottlenose whale, none of these species should be 
considered cryptic (i.e., difficult to observe when present) versus 
rare (i.e., not likely to be present). Average group size was 
determined by considering known sightings in the western North Atlantic 
(CETAP, 1982; Hansen et al., 1994; NMFS, 2010a, 2011, 2012, 2013a, 
2014, 2015a; Waring et al., 2007, 2015). It is important to note that 
our proposal to authorize take equating to harassment of one group of 
each of these species is not equivalent to expected exposure. We do not 
expect that these rarely occurring (in the proposed survey area) 
species will be exposed at all but provide a precautionary 
authorization of take. We

[[Page 25289]]

provide a brief description for each of these species below.
    Northern Bottlenose Whale--Northern bottlenose whales are 
considered extremely rare in U.S. Atlantic waters, with only five NMFS 
sightings. The southern extent of distribution is generally considered 
to be approximately Nova Scotia (though Mitchell and Kozicki (1975) 
reported stranding records as far south as Rhode Island), and there 
have been no sightings within the proposed survey areas. Whitehead and 
Wimmer (2005) estimated the size of the population on the Scotian Shelf 
at 163 whales (95 percent CI 119-214). Whitehead and Hooker (2012) 
report that northern bottlenose whales are found north of approximately 
37.5[deg] N and prefer deep waters along the continental slope. Roberts 
et al. (2016) produced a stratified density model on the basis of four 
sightings in the vicinity of Georges Bank (Roberts et al., 2015b). The 
five sightings in U.S. waters yield a mean group size of 2.2 whales, 
while MacLeod and D'Amico report a mean group size of 3.6. Here, we 
propose take of one group of with a maximum group size of four whales.
    Killer Whale--Killer whales are also considered rare in U.S. 
Atlantic waters (Katona et al., 1988; Forney and Wade, 2006), 
constituting 0.1 percent of marine mammal sightings in the 1978-81 
Cetacean and Turtle Assessment Program surveys (CETAP, 1982). Roberts 
et al. (2016) produced a stratified density model on the basis of four 
killer whale sightings (Roberts et al., 2015g), though Lawson and 
Stevens (2014) provide a minimum abundance estimate of 67 photo-
identified individual killer whales. Available information suggests 
that survey encounters with killer whales would be unlikely but could 
occur anywhere within the proposed survey area and at any time of year 
(e.g., Lawson and Stevens, 2014). Silber et al. (1994) reported 
observations of two and 15 killer whales in the Gulf of California 
(mean group size 8.5), while May-Collado et al. (2005) described mean 
group size of 3.6 whales off the Pacific coast of Costa Rica. Based on 
12 CETAP sightings and one group observed during NOAA surveys (CETAP, 
1982; NMFS, 2014), the average group size in the Atlantic is 6.8 
whales. Therefore, we propose take of one group with a maximum group 
size of seven whales.
    False Killer Whale--Although records of false killer whales from 
the U.S. Atlantic are uncommon, a combination of sighting, stranding, 
and bycatch records indicates that this species does occur in the 
western North Atlantic (Waring et al., 2015). Baird (2009) suggests 
that false killer whales may be naturally uncommon throughout their 
range. Roberts et al. (2016) produced a stratified density model on the 
basis of two false killer whale sightings (Roberts et al., 2015m), and 
NMFS produced the first abundance estimate for false killer whales on 
the basis of one sighting during 2011 shipboard surveys (Waring et al., 
2015). Similar to the killer whale, we believe survey encounters would 
be unlikely but could occur anywhere within the proposed survey area 
and at any time of year. Mullin et al. (2004) reported a mean false 
killer whale group size of 27.5 from the Gulf of Mexico, and May-
Collado et al. (2005) described mean group size of 36.2 whales off the 
Pacific coast of Costa Rica. The few sightings from CETAP (1982) and 
from NOAA shipboard surveys give an average group size of 10.3 whales. 
As a precaution, we propose take of one group with a maximum group size 
of 28 whales, as reported from the Gulf of Mexico.
    Pygmy Killer Whale--The pygmy killer whale is distributed worldwide 
in tropical to sub-tropical waters, and is assumed to be part of the 
cetacean fauna of the tropical western North Atlantic (Jefferson et 
al., 1994; Waring et al., 2007). Pygmy killer whales are rarely 
observed by NOAA surveys outside the Gulf of Mexico--one group was 
observed off of Cape Hatteras in 1992--and the rarity of such sightings 
may be due to a naturally low number of groups compared to other 
cetacean species (Waring et al., 2007). NMFS has never produced an 
abundance estimate for this species and Roberts et al. (2016) were not 
able to produce a density model for the species. The 1992 sighting was 
of six whales; therefore, we propose take of one group with a maximum 
group size of six whales.
    Melon-headed Whale--Similar to the pygmy killer whale, the melon-
headed whale is distributed worldwide in tropical to sub-tropical 
waters, and is assumed to be part of the cetacean fauna of the tropical 
western North Atlantic (Jefferson et al., 1994; Waring et al., 2007). 
Melon-headed whales are rarely observed by NOAA surveys outside the 
Gulf of Mexico--groups were observed off of Cape Hatteras in 1999 and 
2002--and the rarity of such sightings may be due to a naturally low 
number of groups compared to other cetacean species (Waring et al., 
2007). NMFS has never produced an abundance estimate for this species 
and Roberts et al. (2016) produced a stratified density model on the 
basis of four sightings (Roberts et al., 2015d). The two sightings 
reported by Waring et al. (2007) yield an average group size of 50 
whales; therefore, we propose take of a single group of a maximum of 50 
whales.
    Spinner Dolphin--Distribution of spinner dolphins in the Atlantic 
is poorly known, but they are thought to occur in deep water along most 
of the U.S. coast south to the West Indies and Venezuela (Waring et 
al., 2014). There have been a handful of sightings in deeper waters off 
the northeast United States and one sighting during a 2011 NOAA 
shipboard survey off North Carolina, as well as stranding records from 
North Carolina south to Florida and Puerto Rico (Waring et al., 2014). 
Roberts et al. (2016) provide a stratified density model on the basis 
of two sightings (Roberts et al., 2015i). Regarding group size, Mullin 
et al. (2004) report a mean of 91.3 in the Gulf of Mexico; May-Collado 
(2005) describe a mean of 100.6 off the Pacific coast of Costa Rica; 
and CETAP (1982) sightings in the Atlantic yield a mean group size of 
42.5 dolphins. As a precaution, we will propose taking a single group 
with a maximum size of 91 dolphins (derived from mean group size 
reported in Mullin et al. 2004).
    Fraser's Dolphin--As was stated for both the pygmy killer whale and 
melon-headed whale, the Fraser's dolphin is distributed worldwide in 
tropical waters, and is assumed to be part of the cetacean fauna of the 
tropical western North Atlantic (Perrin et al., 1994; Waring et al., 
2007). The paucity of sightings of this species may be due to naturally 
low abundance compared to other cetacean species (Waring et al., 2007). 
Despite possibly being more common in the Gulf of Mexico than in other 
parts of its range (Dolar 2009), there were only five reported 
sightings during NOAA surveys from 1992-2009. In the Atlantic, NOAA 
surveys have yielded only two sightings (Roberts et al., 2015f). May-
Collado et al. (2005) reported a single observation of 158 Fraser's 
dolphins off the Pacific coast of Costa Rica, and Waring et al. (2007) 
describe a single observation of 250 Fraser's dolphins in the Atlantic, 
off Cape Hatteras. Therefore, we propose take of a single group with a 
maximum group size of 204 dolphins (derived from average of May-Collado 
et al. 2005 and Waring et al. 2007 sightings data).
    Atlantic White-sided Dolphin--White-sided dolphins are found in 
temperate and sub-polar continental shelf waters of the North Atlantic, 
primarily in the Gulf of Maine and north into Canadian waters (Waring 
et al., 2016). Palka et al. (1997) suggest the existence of stocks in 
the Gulf of Maine, Gulf of St. Lawrence, and Labrador Sea. Stranding 
records from Virginia and North Carolina suggest a southerly winter 
range extent

[[Page 25290]]

of approximately 35[deg] N (Waring et al., 2016); therefore, it is 
possible that the proposed surveys could encounter white-sided 
dolphins. Roberts et al. (2016) elected to split their study area at 
the north wall of the Gulf Stream, separating the cold northern waters, 
representing probable habitat, from warm southern waters, where white-
sided dolphins are likely not present (Roberts et al., 2015k). Over 600 
observations of Atlantic white-sided dolphins during CETAP (1982) and 
during NMFS surveys provide a mean group size estimate of 47.7 
dolphins, while Weinrich et al. (2001) reported a mean group size of 52 
dolphins. Due to this data, we propose take of a single group with a 
maximum group size of 48 dolphins.

     Table 9--Numbers of Incidental Take Proposed for Authorization
------------------------------------------------------------------------
                                     Proposed Level B   Proposed Level A
              Species                    take **              take
------------------------------------------------------------------------
Humpback whale....................                  2                  0
Sei whale.........................                  2                  0
Fin whale.........................                  5                  0
Sperm whale.......................                160                  0
Kogia spp.........................                  9                  0
Beaked whales.....................                128                  0
Northern bottlenose whale *.......                * 4                  0
Rough-toothed dolphin.............                 10                  0
Common bottlenose dolphin.........                757                  0
Clymene dolphin...................                121                  0
Atlantic spotted dolphin..........              1,598                  0
Pantropical spotted dolphin.......                 50                  0
Spinner dolphin *.................               * 91                  0
Striped dolphin...................              1,458                  0
Short-beaked common dolphin.......              1,620                  0
Fraser's dolphin *................              * 204                  0
Atlantic white-sided dolphin *....               * 48                  0
Risso's dolphin...................                236                  0
Melon-headed whale *..............               * 50                  0
Pygmy killer whale *..............                * 6                  0
False killer whale *..............               * 28                  0
Killer whale *....................                * 7                  0
Pilot whales......................                288                  0
------------------------------------------------------------------------
* Proposed Level B take for rare species represent take of a single
  group. The value given for the proposed Level B take is the maximum
  group size allowed for take.
** Proposed take numbers for non-rare species are the same as those
  reported in Table 8.

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.
    USGS 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, USGS has proposed to implement the 
following mitigation measures for marine mammals:
    (1) Vessel-based visual mitigation monitoring;
    (2) Establishment of a marine mammal exclusion zone (EZ);
    (3) Shutdown procedures;
    (4) Ramp-up procedures; and
    (5) Vessel strike avoidance measures.
    In addition to the measures proposed by USGS, NMFS has proposed the 
following mitigation measure: Establishment of a marine mammal buffer 
zone.
    Protected Species Observer (PSO) observations would take place 
during all daytime airgun operations and nighttime start ups (if 
applicable) of the

[[Page 25291]]

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 R/V Hugh R. Sharp 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 (EZ) (as described below).
    During seismic operations, three visual PSOs would be based aboard 
the R/V Hugh R. Sharp. PSOs would be appointed by USGS with NMFS 
approval. During the majority of seismic operations, two PSOs would 
monitor for marine mammals around the seismic vessel. PSO(s) would be 
on duty in shifts of duration no longer than four 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 R/V Hugh R. Sharp is a suitable platform from which PSOs would 
watch for marine mammals. Standard equipment for marine mammal 
observers would be 7 x 50 reticle binoculars, optical range finders, 
and Big Eye binoculars. 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 seismic survey. One ``experienced'' 
visual PSO will be designated as the lead for the entire protected 
species observation team. The lead will serve as primary point of 
contact for the USGS scientist-in-charge or his/her designee. The 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, 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 and Buffer Zone

    An EZ is a defined area within which occurrence of a marine mammal 
triggers mitigation action intended to reduce the potential for certain 
outcomes, e.g., auditory injury, disruption of critical behaviors. The 
PSOs would establish a minimum EZ with a 100 m radius from 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 
Shutdown 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 injury 
criteria (Level A thresholds) 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. As a result no Level A harassment is expected nor 
proposed for this action.
    Our intent in prescribing a standard EZ 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 an additional 100 m buffer 
zone beginning from the outside extant of the 100 m EZ. During use of 
the acoustic source, occurrence of marine mammals within the 100 m 
buffer zone would be communicated to the USGS scientist-in-charge or 
his/her designee to prepare for potential shutdown of the acoustic 
source. The 100 m 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, 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;
     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 and 
dwarf sperm, beaked whales, and large delphinids.
    This shutdown requirement would be in place for all marine mammals, 
with the exception of small delphinoids under certain circumstances. 
This exception to the shutdown requirement would apply solely to 
specific genera of small dolphins--Tursiops, Steno, Stenella, 
Lagenorhynchus and Delphinus--and would only apply if the animals were 
traveling, including approaching the vessel. 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). 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

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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 of small dolphins 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 R/V 
Hugh R. Sharp 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 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 
impacts. In addition, the required shutdown measure may prevent more 
severe behavioral reactions for any large delphnoids in close proximity 
to the source vessel.
    Shutdown of the acoustic source would also be required upon 
observation beyond the 100 m EZ of any of the following:
     A large whale (i.e., sperm whale or any baleen whale) with 
a calf;
     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.); or
     A marine mammal species not authorized (i.e., a north 
Atlantic right whale) for take that is approaching or entering the 
Level B zone.
     An authorized marine mammal species that has reached its 
total allotted Level B take that is approaching or entering the Level B 
zone.
    These would be the only four potential situations that would 
require shutdown of the array for marine mammals observed beyond the 
100 m EZ.

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 to the full array would take 20 
minutes, starting with operation of a single airgun and with one 
additional airgun added every 5 minutes.
    At least two PSOs would be required to monitor during ramp-up. 
During ramp up, the PSOs would monitor the 100 m 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 or 100 m buffer zone during this pre-clearance period, ramp-up 
would not be initiated until all marine mammals cleared the 100 m EZ or 
100 m buffer zone. 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 100 m 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 100 m buffer zone have been monitored by visual 
PSOs for 30 minutes prior to ramp-up.
    The USGS scientist-in-charge or his/her designee 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 USGS scientist-in-charge or his/her designee must receive 
confirmation from the PSO to proceed. The USGS scientist-in-charge or 
his/her designee must provide information to PSOs documenting that 
appropriate procedures were followed. Following deactivation of the 
array for reasons other than mitigation, the USGS scientist-in-charge 
or his/her designee would be required to communicate the near-term 
operational plan to the lead PSO with justification for any planned 
nighttime ramp-up.

Vessel Strike Avoidance Measures

    Vessel strike avoidance measures are intended to minimize the 
potential for collisions with marine mammals. These requirements do not 
apply in any case where compliance would create an imminent and serious 
threat to a person or vessel or to the extent that a vessel is 
restricted in its ability to maneuver and, because of the restriction, 
cannot comply.
    The proposed measures include the following: The USGS scientist-in-
charge or his/her designee, the vessel operator (The University of 
Delaware) and crew would maintain a vigilant watch for all marine 
mammals and slow down or stop the vessel or alter course to avoid 
striking any marine mammal. A visual observer aboard the vessel would 
monitor a vessel strike avoidance zone around the vessel according to 
the parameters stated below. Visual

[[Page 25293]]

observers monitoring the vessel strike avoidance zone would be either 
third-party observers or crew members, but crew members responsible for 
these duties would be provided sufficient training to distinguish 
marine mammals from other phenomena. Vessel strike avoidance measures 
would be followed during surveys and while in transit.
    The vessel would maintain a minimum separation distance of 100 m 
from large whales (i.e., baleen whales and sperm whales). If a large 
whale is within 100 m of the vessel the vessel would reduce speed and 
shift the engine to neutral, and would not engage the engines until the 
whale has moved outside of the vessel's path and the minimum separation 
distance has been established. If the vessel is stationary, the vessel 
would not engage engines until the whale(s) has moved out of the 
vessel's path and beyond 100 m. The vessel would maintain a minimum 
separation distance of 50 m from all other marine mammals (with the 
exception of delphinids of the genera Tursiops, Steno, Stenella, 
Lagenorhynchus and Delphinus that approach the vessel, as described 
above). If an animal is encountered during transit, the vessel would 
attempt to remain parallel to the animal's course, avoiding excessive 
speed or abrupt changes in course. Vessel speeds would be reduced to 10 
kn or less when mother/calf pairs, pods, or large assemblages of 
cetaceans (what constitues ``large'' will vary depending on species) 
are observed within 500 m of the vessel. Mariners may use professional 
judgment as to when such circumstances warranting additional caution 
are present.

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

    In the event of a live stranding (or near-shore atypical milling) 
event within 50 km of the survey operations, where the NMFS stranding 
network is engaged in herding or other interventions to return animals 
to the water, the Director of OPR, NMFS (or designee) will advise the 
IHA-holder of the need to implement shutdown procedures for all active 
acoustic sources operating within 50 km of the stranding. Shutdown 
procedures for live stranding or milling marine mammals include the 
following:
     If at any time, the marine mammal(s) die or are 
euthanized, or if herding/intervention efforts are stopped, the 
Director of OPR, NMFS (or designee) will advise the IHA-holder that the 
shutdown is no longer needed.
     Otherwise, shutdown procedures will remain in effect until 
the Director of OPR, NMFS (or designee) determines and advises the IHA-
holder that all live animals involved have left the area (either of 
their own volition or following an intervention).
     If further observations of the marine mammals indicate the 
potential for re-stranding, additional coordination with the IHA-holder 
will be required to determine what measures are necessary to minimize 
that likelihood (e.g., extending the shutdown or moving operations 
farther away) and to implement those measures as appropriate.
    Shutdown procedures are not related to the investigation of the 
cause of the stranding and their implementation is not intended to 
imply that the specified activity is the cause of the stranding. 
Rather, shutdown procedures are intended to protect marine mammals 
exhibiting indicators of distress by minimizing their exposure to 
possible additional stressors, regardless of the factors that 
contributed to the stranding.
    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 noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the action; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
     Mitigation and monitoring effectiveness.
    USGS submitted a marine mammal monitoring and reporting plan in 
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.
    USGS'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 R/V Hugh R. Sharp. PSOs would be appointed by USGS 
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 four 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, Big Eye binoculars, and with the naked eye. At night, PSOs 
would be equipped with night-vision equipment.
    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

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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; and
    (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 (e.g., 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; and
    (5) Data on the behavior and movement patterns of marine mammals 
seen at times with and without seismic activity.

Reporting Injured or Dead Marine Mammals

    Discovery of Injured or Dead Marine Mammal--In the event that 
personnel involved in the survey activities covered by the 
authorization discover an injured or dead marine mammal, the IHA-holder 
shall report the incident to the Office of Protected Resources (OPR), 
NMFS and to regional stranding coordinators as soon as feasible. The 
report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.
    Vessel Strike--In the event of a ship strike of a marine mammal by 
any vessel involved in the activities covered by the authorization, the 
IHA-holder shall report the incident to OPR, NMFS and to regional 
stranding coordinators as soon as feasible. The report must include the 
following information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Species identification (if known) or description of the 
animal(s) involved;
     Vessel's speed during and leading up to the incident;
     Vessel's course/heading and what operations were being 
conducted (if applicable);
     Status of all sound sources in use;
     Description of avoidance measures/requirements that were 
in place at the time of the strike and what additional measures were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
     Estimated size and length of animal that was struck;
     Description of the behavior of the marine mammal 
immediately preceding and following the strike;
     If available, description of the presence and behavior of 
any other marine mammals immediately preceding the strike;
     Estimated fate of the animal (e.g., dead, injured but 
alive, injured and moving, blood or tissue observed in the water, 
status unknown, disappeared); and
     To the extent practicable, photographs or video footage of 
the animal(s).
    Additional Information Requests--If NMFS determines that the 
circumstances of any marine mammal stranding found in the vicinity of 
the activity suggest investigation of the association with survey 
activities is warranted (example circumstances noted below), and an 
investigation into the stranding is being pursued, NMFS will submit a 
written request to the IHA-holder indicating that the following initial 
available information must be provided as soon as possible, but no 
later than 7 business days after the request for information.
     Status of all sound source use in the 48 hours preceding 
the estimated time of stranding and within 50 km of the discovery/
notification of the stranding by NMFS; and
     If available, description of the behavior of any marine 
mammal(s) observed preceding (i.e., within 48 hours and 50 km) and 
immediately after the discovery of the stranding.
    Examples of circumstances that could trigger the additional 
information request include, but are not limited to, the following:
     Atypical nearshore milling events of live cetaceans;
     Mass strandings of cetaceans (two or more individuals, not 
including cow/calf pairs);
     Beaked whale strandings;
     Necropsies with findings of pathologies that are unusual 
for the species or area; or
     Stranded animals with findings consistent with blast 
trauma.
    In the event that the investigation is still inconclusive, the 
investigation of the association of the survey activities is still 
warranted, and the investigation is still being pursued, NMFS may 
provide additional information requests, in writing, regarding the 
nature and location of survey operations prior to the time period 
above.

Reporting

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

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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).
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of USGS'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.
    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 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 feeding, mating or calving areas 
known to be biologically important to marine mammals within the 
proposed project area during the time of the survey (Ferguson et al., 
2015). Also, as stated, the survey slightly intersects with a core 
abundance area for sperm whales. However, due to the low energy-source 
of the airguns for the action and the proposed mitigation measures 
listed above, NMFS does not exclude USGS from this area during its 
survey, nor does it foresee the survey having effects, greater than 
negligible impact, on the core abundance area.
    As described previously, there are multiple species that should be 
considered rare in the proposed survey areas and for which we propose 
to authorize only nominal and precautionary take of a single group. We 
do not expect meaningful impacts to these species (i.e., killer whale, 
false killer whale, pygmy killer whale, melon-headed whale, northern 
bottlenose whale, spinner dolphin, Fraser's dolphin, Atlantic white-
sided dolphin) because we preliminarily find that the total marine 
mammal take from each of the specified activities will have a 
negligible impact on these marine mammal species. Therefore, we do not 
discuss these eight species further in this negligible impact analysis.
    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 (22 days with 19 days of airgun operations) 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 all 
Level A harassment and most Level B harassment.
    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; fin, sei, and sperm whales. There are 
currently insufficient data to determine population trends for these 
species (Hayes et al., 2017); however, we are proposing to authorize 
very small numbers of takes for these species (Table 8), relative to 
their population sizes (again, when compared to mean abundance 
estimates, for purposes of comparison only). 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 USGS'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; 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 due to 
USGS'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. Marine mammals may temporarily avoid the immediate area but 
are not expected to permanently abandon the area. Major shifts in 
habitat use, distribution, or foraging success are not expected. NMFS 
does not anticipate the proposed take estimates to impact annual rates 
of recruitment or survival.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No injury (Level A take), serious injury or 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

[[Page 25296]]

relatively short duration of the proposed survey (22 days with 19 days 
of airgun operations) would further limit the potential impacts of any 
temporary behavioral changes that would occur;
     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; and
     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 for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers and so, in practice, where estimated numbers are 
available, NMFS compares the number of individuals taken to the most 
appropriate estimation of abundance of the relevant species or stock in 
our determination of whether an authorization is limited to small 
numbers of marine mammals. Additionally, other qualitative factors may 
be considered in the analysis, such as the temporal or spatial scale of 
the activities.
    Please see Tables 8 and 9 and the related text for information 
relating to the basis for our small numbers analyses. Table 8 provides 
the numbers of predicted exposures above specified received levels, 
while Table 9 provides numbers of take proposed for authorization. For 
the northern bottlenose whale, Fraser's dolphin, melon-headed whale, 
false killer whale, pygmy killer whale, killer whale, spinner dolphin, 
and white-sided dolphin, we propose to authorize take resulting from a 
single exposure of one group of each species or stock, as appropriate 
(using average group size), for each applicant. As stated earlier, we 
believe that a single incident of take of one group of any of these 
species represents take of small numbers for that species. Therefore, 
based on the analyses contained herein of the specified activity, we 
preliminarily find that small numbers of marine mammals will be taken 
for each of these eight affected species or stocks for the specified 
activity. We do not discuss these eight species further in this small 
numbers analysis.
    As shown in Table 8, we used mean abundance estimates from Roberts 
(2016) to calculate the percentage of population that is estimated to 
be taken during the proposed activities for non-rare species. These 
data present the best available abundance estimates for cetacean 
populations off of the Western Atlantic for this proposed activity. The 
activity is expected to impact a very small percentage of all marine 
mammal populations. As presented in Table 8, take of all 21 marine 
mammal species authorized for take is less than three percent of the 
abundance estimate.
    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 Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS consults internally, in this case with the ESA Interagency 
Cooperation Division, whenever we propose to authorize take for 
endangered or threatened species.
    NMFS is proposing to authorize take of three species of marine 
mammals which are listed under the ESA: The sei whale, fin whale, and 
sperm whale. The Permits and Conservation Division has requested 
initiation of Section 7 consultation with the ESA Interagency 
Cooperation Division for the issuance of this IHA. NMFS will conclude 
the ESA consultation prior to reaching a determination regarding the 
proposed issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to USGS for conducting a marine geophysical survey in the 
Northwest Atlantic Ocean in August 2018, 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 USGS IHA application and using an airgun array 
aboard the R/V Hugh R. Sharp with characteristics specified in the 
application, in the Northwest Atlantic Ocean.
    3. General Conditions
    (a) A copy of this IHA must be in the possession of USGS, the 
vessel operator (The University of Delaware) and other relevant 
personnel, the lead PSO, and any other relevant designees of USGS 
operating under the authority of this IHA.
    (b) The species authorized for taking are listed in Table 9. The 
taking, by Level B harassment only, is limited to the species and 
numbers listed in Table 9. Any taking exceeding the authorized amounts 
listed in Table 9 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 9 are detected by PSOs, the acoustic source 
must be shut down to avoid unauthorized take.
    (e) The USGS scientist-in-charge or his/her designee 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

[[Page 25297]]

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:
    (a) USGS must use at least three (3) dedicated, trained, NMFS-
approved PSOs. The PSOs must have no tasks other than to conduct 
observational effort, record observational data, and communicate with 
and instruct relevant vessel crew with regard to the presence of marine 
mammals and mitigation requirements. PSO resumes shall be provided to 
NMFS for approval.
    (b) 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 USGS scientist-in-
charge or his/her designee.
    (c) 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), at least 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 (except during transits across the 
shelf where no seismic activity will occur during the survey) for 
comparison of sighting rates and behavior with and without use of the 
acoustic source and between acquisition periods, to the maximum extent 
practicable.
    (d) Exclusion Zone and Buffer Zone--PSOs shall establish and 
monitor a 100 m EZ and an additional 100 m buffer zone beginning from 
the outside extant of the 100 m EZ. The zones shall be based upon 
radial distance from 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 100 m buffer zone from any element of the airgun array shall 
be communicated to the USGS scientist-in-charge or his/her designee to 
prepare for potential further mitigation measures as described below. 
During use of the acoustic source, occurrence of marine mammals within 
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 shall begin with 
starting one 105 in\3\ airgun with additional 105 in\3\ airguns being 
turned on every 5 minutes until all four airguns are in operation.
    (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 and dwarf sperm, beaked 
whales, and large delphinids).
    (iii) Thirty minutes of pre-clearance observation of the 100 m EZ 
and 100 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 EZ or 100 m buffer zone during the 
30 minute pre-clearance period, ramp-up may not begin until the 
animal(s) has been observed exiting the EZ or 100 m buffer zone 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 and dwarf sperm, beaked 
whales, and large delphinids).
    (iv) During ramp-up, at least two PSOs shall conduct monitoring. 
Ramp-up may not be initiated if any marine mammal (including 
delphinids) is observed within or approaching the 100 m EZ or 100 m 
buffer zone. 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 in the 100 m EZ 
(i.e., 15 minutes for small odontocetes and 30 minutes for mysticetes 
and large odontocetes including sperm, pygmy and dwarf sperm, beaked 
whales, and large delphinids).
    (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 100 m EZ or 100 m 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 100 m buffer zone have been continually monitored by 
visual PSOs for 30 minutes prior to ramp-up with no marine mammal 
detections.
    (vii) The USGS scientist-in-charge or his/her designee must notify 
a designated PSO of the planned start of ramp-up. The designated PSO 
must be notified again immediately prior to initiating ramp-up 
procedures and the USGS scientist-in-charge or his/her designee must 
receive confirmation from the PSO to proceed.
    (e) Shutdown requirements--A 100 m EZ 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 USGS scientist-in-charge or his/her designee 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.

[[Page 25298]]

    (iv) The shutdown requirement is waived for dolphins of the 
following genera: Tursiops, Steno, Stenella, Lagenorhynchus and 
Delphinus. The shutdown waiver only applies if animals are traveling, 
including approaching the vessel. If these 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 observations of a 
marine mammal species not authorized (i.e., a north Atlantic right 
whale) for take that is entering or approaching the vessel's respective 
Level B zone (See Table 5).
    (ix) Shutdown of the array is required upon observations of an 
authorized marine mammal species that has reached its total allotted 
Level B take that is entering or approaching the vessel's respective 
Level B zone (See Table 5).
    (f) Vessel Strike Avoidance--The USGS, PSOs, vessel operator, and 
crew must maintain a vigilant watch for all marine mammals and the 
vessel operator must slow down or stop the vessel or alter course, as 
appropriate, to avoid striking any marine mammal. These requirements do 
not apply in any case where compliance would create an imminent and 
serious threat to a person or vessel or to the extent that a vessel is 
restricted in its ability to maneuver and, because of the restriction, 
cannot comply. 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. 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.
    (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.
    (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 parallel 
to the animal's course, avoiding excessive speed or abrupt changes in 
course.
    (iii) Vessel speeds must be reduced to 10 knots or less when 
mother/calf pairs or large assemblages of cetaceans (what constitues 
``large'' will vary depending on species) are observed within 500 m of 
the vessel. Mariners may use professional judgment as to when such 
circumstances warranting additional caution are present.
    (g) 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 
840 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 USGS scientist-in-charge or his/her designee 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), Big Eye 
binoculars, GPS, 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

[[Page 25299]]

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.); and
    (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 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) USGS shall submit a draft comprehensive report on all 
activities and monitoring results within 90 days of the completion of 
the survey or 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, USGS shall immediately 
cease the specified activities and immediately report the incident to 
the NMFS Office of Protected Resources and to regional stranding 
coordinators as soon as feasible. 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) Vessel's course/heading and what operations were being 
conducted (if
    (D) applicable);
    (E) Status of all sound sources in use;
    (F) Description of avoidance measures/requirements that were in 
place at the time of the strike and what additional measures were 
taken, if any, to avoid strike;
    (G) Description of the incident;
    (H) Status of all sound source use in the 24 hours preceding the 
incident;
    (I) Water depth;
    (J) Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, and visibility);
    (K) Description of all marine mammal observations in the 24 hours 
preceding the incident;
    (L) Species identification or description of the animal(s) 
involved;
    (M) Fate of the animal(s); and
    (N) Photographs or video footage of the animal(s).
    (ii) Activities shall not resume until NMFS is able to review the 
circumstances of the prohibited take. NMFS will work with USGS to 
determine what measures are necessary to minimize the likelihood of 
further prohibited take and ensure MMPA compliance. USGS may not resume 
their activities until notified by NMFS.
    (iii) In the event that USGS 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), USGS shall immediately report 
the incident to the NMFS Office of Protected Resources. 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 USGS to determine whether additional 
mitigation measures or modifications to the activities are appropriate.
    (iv) In the event that USGS 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), USGS shall report the incident to 
the

[[Page 25300]]

NMFS Office of Protected Resources within 24 hours of the discovery. 
USGS 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 proposed authorization, and 
any other aspect of this Notice of Proposed IHA for the proposed 
[action]. We also request comment on the potential for renewal of this 
proposed IHA as described in the paragraph below. Please include with 
your comments any supporting data or literature citations to help 
inform our final decision on the request for MMPA authorization.

    Dated: May 24, 2018.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2018-11629 Filed 5-30-18; 8:45 am]
 BILLING CODE 3510-22-P