Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to a Low-Energy Geophysical Survey in the Northwest Atlantic Ocean, 18664-18695 [2018-08891]

Agencies

• DEPARTMENT OF COMMERCE
• National Oceanic and Atmospheric Administration

[Federal Register Volume 83, Number 82 (Friday, April 27, 2018)]
[Notices]
[Pages 18664-18695]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-08891]



[[Page 18663]]

Vol. 83

Friday,

No. 82

April 27, 2018

Part II





Department of Commerce





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National Oceanic and Atmospheric Administration





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

Federal Register / Vol. 83 , No. 82 / Friday, April 27, 2018 / 
Notices

[[Page 18664]]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XF986


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to a Low-Energy 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 the Scripps Institution of 
Oceanography (SIO) for authorization to take marine mammals incidental 
to a low-energy 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 
authorization and agency responses will be summarized in the final 
notice of our decision.

DATES: Comments and information must be received no later than May 29, 
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: Jordan Carduner, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the application 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained online at: www.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. This action is consistent with categories of 
activities identified in Categorical Exclusion B4 (incidental 
harassment authorizations with no anticipated serious injury or 
mortality) of the Companion Manual for NOAA Administrative Order 216-
6A, which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has 
preliminarily determined that the issuance of the proposed IHA 
qualifies to be categorically excluded from further NEPA review.

Summary of Request

    On November 20, 2017, NMFS received a request from SIO for an IHA 
to take marine mammals incidental to conducting a low-energy marine 
geophysical survey in the Northwest Atlantic Ocean. On February 8, 
2018, we deemed SIO's application for authorization to be adequate and 
complete. SIO's request is for take of a small number of 35 species of 
marine mammals by Level B harassment and Level A harassment. Neither 
SIO nor NMFS expects mortality to result from this activity, and, 
therefore, an IHA is appropriate. The planned activity is not expected 
to exceed one year, hence, we do not expect subsequent MMPA incidental 
harassment authorizations would be issued for this particular activity.

Description of Proposed Activity

Overview

    SIO proposes to conduct low-energy marine seismic surveys in the 
Northwest Atlantic Ocean during June-July 2018. The surveys would take 
place in International Waters in water deeper than 1,000 meters (m) 
(See Figure 1 in the IHA application). The proposed surveys would 
involve one source vessel, the R/V Atlantis. The Atlantis would tow a 
pair of 45 cubic inch (in\3\) GI airguns at a depth of 2-4 m with a 
total discharge volume of approximately

[[Page 18665]]

90 in\3\ as an energy source along predetermined lines.

Dates and Duration

    The seismic survey would be carried out for approximately 25 days. 
The Atlantis would likely depart from St. George's, Bermuda, on or 
about June 14, 2018 and would return to Woods Hole, Massachusetts, on 
or about July 17, 2018. Some deviation in timing could result from 
unforeseen events such as weather, logistical issues, or mechanical 
issues with the research vessel and/or equipment. Seismic activities 
would occur 24 hours per day during the proposed survey.

Specific Geographic Region

    The proposed surveys would take place in International Waters of 
the Northwest Atlantic Ocean, between ~33.5[deg] and 53.5[deg] N, and 
37[deg] and 49[deg] W. Representative survey track lines for the survey 
area is shown in Figure 1 of the IHA application. The Atlantis would 
depart from St. George's, Bermuda, and would return to Woods Hole, 
Massachusetts.

Detailed Description of Specific Activity

    SIO proposes to conduct low-energy seismic surveys low-energy 
seismic surveys in the Northwest Atlantic Ocean in International Waters 
between ~33.5[deg] and 53.5[deg] N, and 37[deg] and 49[deg] W, in water 
deeper than 1,000 m. The survey area and representative survey 
tracklines are shown in Figure 1 in the IHA application. As described 
above, some deviation in actual tracklines and timing could be 
necessary. The proposed surveys would be in support of a potential 
future International Ocean Discovery Program (IODP) project and would 
examine regional seismic stratigraphy and provide seismic images of 
changing sediment distributions from deepwater production changes. The 
proposed surveys would thus take place in an area that is of interest 
to the IODP and that has older Deep Sea Drilling Project (DSDP) sites. 
To achieve the program's goals, the Principal Investigators propose to 
collect low-energy, high-resolution multi-channel seismic (MCS) 
profiles.
    The procedures to be used for the seismic surveys would be similar 
to those used during previous seismic surveys by SIO and would use 
conventional seismic methodology. The surveys would involve one source 
vessel, R/V Atlantis, which is operated by Woods Hole Oceanographic 
Institution (WHOI). R/V Atlantis would deploy a pair of 45-in\3\ GI 
airguns as an energy source with a total volume of 90 in\3\. The 
receiving system would consist of one hydrophone streamer, either 200 
or 600 m in length, as described below. As the airguns are towed along 
the survey lines, the hydrophone streamer would receive the returning 
acoustic signals and transfer the data to the on-board processing 
system.
    The proposed surveys would consist of: (1) Digital bathymetric, 
echosounding and MCS surveys at six locations to enable the selection 
and analysis of potential future IODP drill sites (see Survey Areas 1-6 
in Figure 1 in the IHA application); and (2) digital bathymetric, echo-
sounding and MCS reflection profiles that tie the proposed drill sites 
to existing DSDP drill sites and replace poor-quality analog seismic 
data. Each of the six site surveys would consist of grids of ship 
tracks that would be acquired using two different types of airgun array 
configurations. The first would be a reconnaissance grid designed to 
identify the optimum orientation and length of seismic lines needed for 
a second, higher-data quality survey designed to locate exactly the 
most suitable potential future drill site suggested by results of the 
reconnaissance survey. This two-step effort is needed for two reasons. 
First, most of the proposed survey sites have been crossed by low-
resolution, single-channel, analog seismic data collected 30-40 years 
ago, and as such are only marginally suitable for proper drill site 
selection. Second, basement ridges are typically spaced closer than the 
10-20 kilometer (km) resolution of satellite bathymetry that currently 
provides constraints on seafloor features in this region, making it 
necessary to conduct ship-borne bathymetric surveys as a first 
indicator of potential future drill locations.
    Each reconnaissance grid would be collected using a pair of 45-
in\3\ airguns, with airguns spaced 8 m apart at a water depth of 2-4 m, 
with a 200 m hydrophone streamer and with the vessel traveling at 8 
knots (kt). Each high-quality site-selection grid, embedded entirely 
within the boundaries of the reconnaissance grid, would be collected 
using a pair of 45-in\3\ airguns, with airguns spaced 2 m apart at a 
depth of 2-4 m, with a 600 m hydrophone streamer and with the vessel 
traveling at to 5 kt to achieve especially high-quality seismic 
reflection data.
    A reconnaissance grid and an embedded high-quality survey grid 
would be centered at each of the six Survey Areas, as shown in Figure 1 
of the IHA application. Figure 1 of the IHA application also shows 
representative tracklines for a potential reconnaissance grid 
consisting of four 30 nautical mile (nm) long main lines, three 20 nm 
cross lines, and ~60 nm of turns, for a total of ~240 nm data per 
reconnaissance grid. All data, including turns, would be collected 
inside the boundaries of a 40 x 40 nm box. The location, orientation, 
and size of the embedded high-quality survey grid would depend on the 
information obtained during the reconnaissance survey. A potential 
high-quality grid could have 10 intersecting tracklines. A site 
appropriate for potential future drilling by the IODP would be 
identified with each of these high-quality digital data grids. These 
latter grids would comprise at least 120 nm of data. In addition to the 
six site surveys, MCS profiles would be acquired at a speed of 8 kt, 
with a pair of 45-in\3\ airguns towed 8 m apart at a water depth of 2-4 
m, using a 200-m streamer.
    The six proposed site surveys would collect up to 4,334 km of data; 
survey lines connecting several grids and existing DSDP drill sites, as 
shown in Figure 1, comprise another 3,577 km, for a total of 7,911 km 
of seismic acquisition. All data would be collected in water depths of 
more than 1,000 m. There could be additional seismic operations in the 
project area associated with equipment testing, re-acquisition due to 
equipment malfunction, data degradation during poor weather, or 
interruption due to shutdown or track deviation in compliance with IHA 
requirements. To account for these additional seismic operations, 25 
percent has been added in the form of operational days, which is 
equivalent to adding 25 percent to the proposed line km to be surveyed.
    In addition to the operations of the airgun array, a multibeam 
echosounder (MBES) and a sub-bottom profiler (SBP) would also be 
operated continuously throughout the survey, but not during transits to 
and from the project area. All planned geophysical data acquisition 
activities would be conducted by SIO with on-board assistance by the 
scientists who have proposed the study. The vessel would be self-
contained, and the crew would live aboard the vessel for the entire 
cruise.
    The Atlantis has a length of 84 m, a beam of 16 m, and a maximum 
draft of 5.8 m. The ship is powered by diesel electric motors and 1,180 
SHP azimuthing stern thrusters. An operation speed of approximately 5-8 
kt (9-15 km/hr) would be used during seismic acquisition. When not 
towing seismic survey gear, the Atlantis cruises at approximately 11 kt 
(20 km/hr). It has a normal operating range of approximately 32,000 km. 
The Atlantis would also serve as the platform from

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which vessel-based protected species visual observers (PSO) would watch 
for marine mammals during airgun operations.
    During the survey, the Atlantis would tow a pair of 45-in\3\ GI 
airguns and a 200- or 600-m long streamer containing hydrophones along 
predetermined lines. The generator chamber of each GI airgun, the one 
responsible for introducing the sound pulse into the ocean, is 45 
in\3\. The larger (105 in\3\) injector chamber injects air into the 
previously generated bubble to maintain its shape, and does not 
introduce more sound into the water. The two 45-in\3\ GI airguns would 
be towed 21 m behind R/V Atlantis, 2 m (during 5-kt grid surveys) or 8 
m (8-kt reconnaissance and seismic transect surveys) apart side by 
side, at a depth of 2-4 m. Surveys with the 2-m airgun separation 
configuration would use a 600-m hydrophone streamer, whereas surveys 
with the 8-m airgun separation configuration would use a 200-m 
hydrophone streamer. Seismic pulses would be emitted at intervals of 25 
m for the 5 kt surveys using the 2-m GI airgun separation and at 
intervals of 50 m for the 8 kt surveys using the 8-m airgun separation.

        Table 1--Specifications of the R/V Atlantis Airgun Array
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Number of airguns.........................  2.
Gun positions used........................  Two inline airguns 2- or 8-m
                                             apart.
Tow depth of energy source................  2-4 m.
Dominant frequency components.............  0-188 Hz.
Air discharge volume......................  Approximately 90 in\3\.
Shot interval.............................  7.8 seconds.
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    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see ``Proposed 
Mitigation'' and ``Proposed Monitoring and Reporting'').

Description of Marine Mammals in the Area of Specified Activities

    Section 4 of the application summarizes available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS' website 
(www.fisheries.noaa.gov/find-species).
    The populations of marine mammals considered in this document do 
not occur within the U.S. EEZ and are therefore not assigned to stocks 
and are not assessed in NMFS' Stock Assessment Reports (SAR). As such, 
information on potential biological removal (PBR; defined by the MMPA 
as the maximum number of animals, not including natural mortalities, 
that may be removed from a marine mammal stock while allowing that 
stock to reach or maintain its optimum sustainable population) and on 
annual levels of serious injury and mortality from anthropogenic 
sources are not available for these marine mammal populations. 
Abundance estimates for marine mammals in the survey location are 
lacking; therefore the abundance estimates presented here are based on 
the U.S. Atlantic SARs (Hayes et al., 2017), as this is considered the 
best available information on potential abundance of marine mammals in 
the area. However, as described above, the marine mammals encountered 
by the proposed survey are not assigned to stocks. All abundance 
estimate values presented in Table 2 are the most recent available at 
the time of publication and are available in the 2017 U.S. Atlantic 
draft SARs (e.g., Hayes et al. 2017) available online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments, except where noted otherwise.
    Table 2 lists all species with expected potential for occurrence in 
the survey area and with the potential to be taken as a result of the 
proposed survey, and summarizes information related to the population, 
including regulatory status under the MMPA and ESA. For taxonomy, we 
follow Committee on Taxonomy (2016).

 Table 2--Marine Mammal Species Potentially Present in the Project Area Expected To Be Affected by the Specified
                                                   Activities
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                                                       ESA/MMPA status;
             Species                     Stock          Strategic (Y/N)     Abundance \2\    Relative occurrence
                                                              \1\                              in project area
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                      Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family: Balaenopteridae:
    Humpback whale \3\            n/a................  -/-; N            12,312............  Uncommon.
     (Megaptera novaeangliae).
    Minke whale \4\               n/a................  -/-; N            20,741............  Uncommon.
     (Balaenoptera
     acutorostrata).
    Bryde's whale (Balaenoptera   n/a................  -/-; N            unknown...........  Uncommon.
     brydei).
    Sei whale (Balaenoptera       n/a................  E/D; Y            357...............  Uncommon.
     borealis).
    Fin whale \4\ (Balaenoptera   n/a................  E/D; Y            3,522.............  Uncommon.
     physalus).
    Blue whale (Balaenoptera      n/a................  E/D; Y            440...............  Uncommon.
     musculus).
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        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family: Physeteridae:
    Sperm whale (Physeter         n/a................  E/D; Y            2,288.............  Uncommon.
     macrocephalus).
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        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family: Kogiidae:
    Pygmy sperm whale \5\ (Kogia  n/a................  -/-; N            3,785.............  Rare.
     breviceps).
    Dwarf sperm whale \5\ (Kogia  n/a................  -/-; N            3,785.............  Rare.
     sima).
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[[Page 18667]]

 
        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family: Delphinidae:
    Killer whale (Orcinus orca).  n/a................  -/-; N            unknown...........  Uncommon.
    False killer whale            n/a................  -/-; N            442...............  Uncommon.
     (Pseudorca crassidens).
    Pygmy killer whale (Feresa    n/a................  -/-; N            unknown...........  Rare.
     attenuata).
    Short-finned pilot whale      n/a................  -/-; N            21,515............  Uncommon.
     (Globicephala
     macrorhynchus).
    Long-finned pilot whale       n/a................  -/-; N            5,636.............  Uncommon.
     (Globicephala melas).
    Harbor porpoise (Phocoena     n/a................  -/-; N            79,833............  Uncommon.
     phocoena).
    Bottlenose dolphin (Tursiops  n/a................  -/-; N            77,532............  Uncommon.
     truncatus).
    Striped dolphin (Stenella     n/a................  -/-; N            54,807............  Uncommon.
     coeruleoala).
    Risso's dolphin (Grampus      n/a................  -/-; N            18,250............  Uncommon.
     griseus).
    Common dolphin \4\            n/a................  -; N              173,486...........  Uncommon.
     (Delphinus delphis).
    Atlantic white-sided dolphin  n/a................  -; N              48,819............  Uncommon.
     (Lagenorhynchus
     obliquidens).
    Atlantic spotted dolphin      n/a................  -; N              44,715............  Uncommon.
     (Stenella frontalis).
    Pantropical spotted dolphin   n/a................  -; N              3,333.............  Uncommon.
     (Stenella attenuate).
    White beaked dolphin          n/a................  -; N              2,003.............  Uncommon.
     (Lagenorhynchus
     albirostris).
    Rough-toothed dolphin (Steno  n/a................  -; N              271...............  Rare.
     bredanensis).
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        Order Cetartiodactyla--Cetacea--Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
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Family: Ziphiidae:
    Cuvier's beaked whale         n/a................  -/-; N            6,532.............  Uncommon.
     (Ziphius cavirostris).
    Blainville's beaked whale     n/a................  -; N              7,092.............  Uncommon.
     \6\ (Mesoplodon
     densirostris).
    True's beaked whale \6\       n/a................  -/-; N            7,092.............  Rare.
     (Mesoplodon mirus).
    Gervais beaked whale \6\      n/a................  -; N              7,092.............  Uncommon.
     (Mesoplodon europaeus).
    Sowerby's beaked whale \6\    n/a................  -; N              7,092.............  Uncommon.
     (Mesoplodon bidens).
    Northern bottlenose whale     n/a................  -; N              unknown...........  Uncommon.
     (Hyperoodon ampullatus).
----------------------------------------------------------------------------------------------------------------
                                     Order Carnivora--Superfamily Pinnipedia
----------------------------------------------------------------------------------------------------------------
Family: Phocidae (earless
 seals):
    Hooded seal (Cystophora       n/a................  -; N              592,100...........  Rare.
     cristata).
    Harp seal (Pagophilus         n/a................  -; N              7,100,000.........  Rare.
     groenlandicus).
    Ringed seal (Pusa hispida)    n/a................  -; N              unknown...........  Rare.
     \7\.
----------------------------------------------------------------------------------------------------------------
\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\ Abundance estimates are from the NMFS 2017 draft Atlantic SAR (Hayes et al., 2017) unless otherwise noted.
  We note that marine mammals in the survey area would not belong to NMFS stocks, as the survey area is outside
  the geographic boundaries for stock assessments, thus stock abundance estimates are provided for comparison
  purposes only.
\3\ NMFS defines a stock of humpback whales only on the basis of the Gulf of Maine feeding population; however,
  multiple feeding populations originate from the Distinct Population Segment (DPS) that is expected to occur in
  the proposed survey area (the West Indies DPS). As West Indies DPS whales from multiple feeding populations
  may be encountered in the proposed survey area, the total abundance of the West Indies DPS best reflects the
  abundance of the population that may encountered by the proposed survey. The West Indies DPS abundance
  estimate shown here reflects the latest estimate as described in the NMFS Status Review of the Humpback Whale
  under the Endangered Species Act (Bettridge et al., 2015).
\4\ Abundance for these species is from the 2007 Canadian Trans-North Atlantic Sighting Survey (TNASS), which
  provided full coverage of the Atlantic Canadian coast (Lawson and Gosselin, 2009). Abundance estimates from
  TNASS were corrected for perception and availability bias, when possible. In general, where the TNASS survey
  effort provided superior coverage of a stock's range (as compared with NOAA shipboard survey effort), we elect
  to use the resulting abundance estimate over the current NMFS abundance estimate (derived from survey effort
  with inferior coverage of the stock range).
\5\ Abundance estimate represents pygmy and dwarf sperm whales combined.
\6\ Abundance estimate represents all species of Mesoplodon in the Atlantic.
\7\ NMFS does not have a defined stock of ringed seals in the Atlantic Ocean.

    Four marine mammal species that are listed under the Endangered 
Species Act (ESA) may be present in the survey area and are included in 
the take request: The fin whale, sei whale, blue whale and sperm whale.
    Below is a description of the species that are both common in the 
survey area and that have the highest likelihood of occurring in the 
survey area and thus are expected to have the potential to be taken by 
the proposed activities. Though other marine mammal species are known 
to occur in the North Atlantic Ocean, the temporal and/or spatial 
occurrence of several of these species is such that take of these 
species is not expected to occur, and they are therefore not discussed 
further beyond the explanation provided here. Four cetacean species, 
although present in the wider North Atlantic Ocean, likely would not be 
found near the proposed project area because their ranges generally do 
not extend as far north: Clymene dolphin, Fraser's dolphin, spinner 
dolphin, and melon-headed

[[Page 18668]]

whale. Another cetacean species, the North Atlantic right whale, occurs 
in nearshore waters off the U.S. coast, and its range does not extend 
as far offshore as the proposed project area. Another three cetacean 
species occur in arctic waters, and their ranges generally do not 
extend as far south as the proposed project area: The bowhead whale, 
narwhal, and beluga. Two additional cetacean species, the Atlantic 
humpback dolphin (which occurs in coastal waters of western Africa) and 
the long-beaked common dolphin (which occurs in coastal waters of South 
America and western Africa) do not occur in deep offshore waters. 
Several pinniped species also are known to occur in North Atlantic 
waters, but are not expected to occur in deep offshore waters of the 
proposed project area, including the gray seal, harbor seal, and 
bearded seal.
    We have reviewed SIO's species descriptions, including life history 
information, distribution, regional distribution, diving behavior, and 
acoustics and hearing, for accuracy and completeness. We refer the 
reader to Section 4 of SIO's IHA application, rather than reprinting 
the information here.

Humpback Whale

    Humpback whales are found worldwide in all ocean basins. In winter, 
most humpback whales occur in the subtropical and tropical waters of 
the Northern and Southern Hemispheres (Muto et al., 2015). These 
wintering grounds are used for mating, giving birth, and nursing new 
calves. Humpback whales were listed as endangered under the Endangered 
Species Conservation Act (ESCA) in June 1970. In 1973, the ESA replaced 
the ESCA, and humpbacks continued to be listed as endangered. NMFS 
recently evaluated the status of the species, and on September 8, 2016, 
NMFS divided the species into 14 distinct population segments (DPS), 
removed the current species-level listing, and in its place listed four 
DPSs as endangered and one DPS as threatened (81 FR 62259; September 8, 
2016). The remaining nine DPSs were not listed. The West Indies DPS, 
which is not listed under the ESA, is the only DPS of humpback whale 
that is expected to occur in the survey area.
    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. Several sightings have been made in water >2,000 m deep during the 
summer to the west of SIO's proposed Survey Areas 4, 5, and 6, and 
northwest of Survey Area 6 (Figure 1 in the IHA application) (DFO 
Sightings Database 2017; OBIS, 2017). Two humpback whales outfitted 
with satellite transmitters near the Dominican Republic during winter 
and spring of 2008 to 2012 were later reported off the east coast of 
Canada, as well as near the proposed project area between Survey Sites 
4 and 5 (Kennedy et al. 2014). Humpback whales were sighted during a 
summer survey along the Mid-Atlantic Ridge from Iceland to north of the 
Azores, including east of the survey area (Waring et al. 2008) and they 
have also been sighted near the Mid-Atlantic Ridge near the Azores 
(Silva et al. 2014; OBIS, 2017). Humpback whales could be encountered 
in the proposed project area during June-July, especially north of 
40[deg] N.

Minke Whale

    The minke whale has a cosmopolitan distribution ranging from the 
tropics and subtropics to the ice edge in both hemispheres (Jefferson 
et al. 2008). Some populations migrate from high latitude summering 
grounds to lower latitude wintering grounds (Jefferson et al. 2015). In 
the Northern Hemisphere, the minke whale is usually seen in coastal 
areas, but can also occur in pelagic waters during northward migrations 
in spring and summer, and southward migration in autumn (Stewart and 
Leatherwood, 1985; Perrin and Brownell, 2009). 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. One minke whale was sighted 
during a summer survey along the Mid-Atlantic Ridge from Iceland to 
north of the Azores, east of SIO's proposed Survey Area 5 (Figure 1 in 
the IHA application) (Waring et al., 2008), and one sighting was made 
during June 2006 to the east of SIO's proposed Survey Area 6 at 
53.3[deg] N, 40.9[deg] W (OBIS 2017). Other minke whale sightings have 
also been reported between the proposed project area and the Mid-
Atlantic Ridge (OBIS 2017), and sightings have been made to the west of 
SIO's proposed Survey Areas 2 to 6 during summer and other seasons (DFO 
Sightings Database 2017; OBIS 2017).

Bryde's Whale

    Bryde's whales are distributed worldwide in tropical and sub-
tropical waters, but the taxonomy and number of species and/or 
subspecies of Bryde's whales in the world is currently a topic of 
debate (Kato and Perrin 2009; Rosel and Wilcox 2014). In the western 
Atlantic Ocean, Bryde's whales are reported from the southeastern 
United States including the Gulf of Mexico and the southern West Indies 
to Cabo Frio, Brazil (Leatherwood and Reeves, 1983). Bryde's whales 
have been observed feeding in the Azores during their northward spring 
migration (Villa et al. 2011), but the distribution of Bryde's whale 
elsewhere in the North Atlantic is not well known, though there are 
records from Virginia south to Brazil in the west, and from Morocco 
south to Cape of Good Hope in the east (Kato and Perrin, 2009). There 
was one Bryde's whale sighting reported at ~40[deg] N during a survey 
along the Mid-Atlantic Ridge north of the Azores (Waring et al. 2008). 
Bryde's whales could be encountered in the proposed project area during 
June-July.

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. Sei whales are regularly sighted near the Azores during spring 
(V[iacute]kingsson et al. 2010; Ryan et al. 2013; Silva et al. 2014), 
and numerous sightings have also been made there during summer (Silva 
et al. 2014; OBIS 2017). One sei whale that was tagged in the Azores 
during 2005 (Olsen et al. 2009) and seven individuals that were tagged 
in the Azores during May-June 2008 and 2009 travelled to the Labrador 
Sea, where they spent extended periods of time on the northern shelf, 
presumably to feed (Prieto et al. 2010, 2014), then travelled 
northbound from the Azores just to the east of SIO's proposed Survey 
Areas 3 and 4, and between Survey Areas 5 and 6, during May and June, 
en route to the Labrador Sea (Olsen et al. 2009; Prieto et al. 2010, 
2014). Sei whales could be encountered in the proposed project area 
during June-July, especially north of 40[deg] N.

[[Page 18669]]

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. Fin whales are 
commonly sighted off Newfoundland and Labrador, with most records for 
June through November (DFO Sightings Database 2017). Several fin whale 
sightings have been made to the west of SIO's proposed Survey Areas 3 
to 6 (see Figure 1 in IHA application) (DFO Sightings Database 2017; 
OBIS 2017). One sighting was made near SIO's proposed Survey Area 5 at 
53[deg] N, 40[deg] W (OBIS 2017). Fin whales were sighted during a 
summer survey along the Mid-Atlantic Ridge from Iceland to north of the 
Azores, including east of SIO's proposed Survey Area 5 and between 40 
and 45[deg] N (Waring et al. 2008). Several sightings have also been 
made between the proposed project area and the Mid-Atlantic Ridge (OBIS 
2017) and fin whales were seen near the Mid-Atlantic Ridge at ~60[deg] 
N in July 2012 (Ryan et al. 2013). Fin whales could be encountered in 
the proposed project area during June-July, especially north of 40[deg] 
N.

Blue Whale

    The blue whale has a cosmopolitan distribution and tends to be 
pelagic, only coming nearshore to feed and possibly to breed (Jefferson 
et al. 2008). Blue whale migration is less well defined than for some 
other rorquals, and their movements tend to be more closely linked to 
areas of high primary productivity, and hence prey, to meet their high 
energetic demands (Branch et al. 2007). Generally, blue whales are 
seasonal migrants between high latitudes in the summer, where they 
feed, and low latitudes in the winter, where they mate and give birth 
(Lockyer and Brown 1981). Some individuals may stay in low or high 
latitudes throughout the year (Reilly and Thayer 1990; Watkins et al. 
2000).
    Blue whales are uncommon in the waters of Newfoundland, but are 
seen from spring through fall, with most sightings reported for July 
and August (DFO Sightings Database 2017). Blue whales have also been 
observed off Newfoundland to the west of SIO's proposed Survey Areas 2 
and 3 (DFO Sightings Database 2017; OBIS 2017), as well as northwest of 
SIO's proposed Survey Area 6 (OBIS 2017). Blue whales were seen during 
a summer survey along the Mid-Atlantic Ridge from Iceland to north of 
the Azores, between 40 and 45[deg] N (Waring et al. 2008). 
Additionally, blue whales outfitted with satellite tags were tracked 
from the Azores northward along the Mid-Atlantic Ridge during spring 
2009 and 2011 (Silva et al. 2013). They have also been sighted in the 
Azores during late spring and summer (Ryan et al. 2013; OBIS 2017). 
Blue whales could be encountered within the proposed project area 
during June-July, but are considered to be uncommon in the area.

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. 
Sightings of sperm whales were also made on and east of the Flemish 
Cap, along the Mid-Atlantic Ridge from at least 32 to 57[deg] N, and 
near SIO's proposed Survey Areas 1-4 and the seismic transects south of 
45.5[deg] N (OBIS 2017). Sperm whales were the second most commonly 
sighted cetacean species (n = 48) during a summer survey along the Mid-
Atlantic Ridge from Iceland to north of the Azores; sightings were more 
abundant at and north of ~52[deg] N, including to the east of SIO's 
proposed Survey Site 5 (Waring et al. 2008). Sperm whales were also 
sighted ~500 km north of Survey Area 1 during the summer 2004 seismic 
survey by L-DEO (Haley and Koski, 2004). There are also numerous 
sightings of sperm whales in the Azores (Morato et al. 2008; Ryan et 
al. 2013; Silva et al. 2014; OBIS 2017). Sperm whales could be 
encountered in the proposed project area during June-July.

Pygmy and 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). Based on density modeling by Mannocci et al. (2017) for 
the western North Atlantic, slightly higher densities are expected to 
occur south of 40[deg] N compared to northern regions. Pygmy and dwarf 
sperm whales likely would 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). There is one record of a Cuvier's beaked whale from June 2006 
between the proposed seismic transects at 51.4[deg] N, 43.1[deg] W, as 
well as numerous sightings from the Azores (Silva et al. 2014; OBIS 
2017). 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 and 
appears to be relatively common

[[Page 18670]]

(Pitman 2009). Relatively few records exist of Mesoplodont beaked whale 
observations in the proposed survey area. There are 16 records of 
Sowerby's beaked whale near the Azores (OBIS 2017) and 10 records of 
stranded Sowerby's beaked whales were recorded in the central group of 
islands in the Azores from 2002 through 2009 (Pereira et al. 2011). 
Mesoplodont beaked whales, including True's, Gervais', Sowerby's, and 
Blainville's beaked whale, may 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). There are two records just 
west of SIO's proposed Survey Area 4, four records for the Mid-Atlantic 
Ridge between 52.8 and 54.3[deg] N, and one record northeast of the 
beginning of the southwestern-most seismic transect (OBIS 2017). 
Northern bottlenose whales were also sighted ~520 km north of Survey 
Area 1 during the summer 2004 seismic survey by L-DEO (Haley and Koski 
2004). Sightings have also been made in the Azores, including during 
summer (Silva et al. 2014; OBIS 2017). Northern bottlenose whales could 
be encountered in the proposed project area.

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). There is one record 
near SIO's proposed Survey Area 6, one near the end of the proposed 
seismic transect heading southwest of Survey Area 6, east of the 
Flemish Cap, and northwest of Survey Area 1 (OBIS 2017). One record was 
made on the Mid-Atlantic Ridge at ~56[deg] N, and there are numerous 
records for the Azores (OBIS 2017). Killer whales could be encountered 
within the proposed project area during June-July.

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). 
There is one record just to the west of Survey Areas 3 and 4, two 
records on the Mid-Atlantic Ridge between 51[deg] and 52[deg] N, and 
numerous records in and around the Azores (OBIS 2017). Silva et al. 
(2014) also reported records for the Azores. False killer whales could 
be encountered in the proposed project area.

Pygmy Killer Whale

    The pygmy sperm 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). There are no records of this species near the 
proposed project area in the OBIS database (OBIS 2017). Pygmy killer 
whales are expected to be rare within and near the proposed project 
area.

Short-Finned Pilot Whale

    Short-finned pilot whales are found in all oceans, primarily in 
tropical and warm-temperate waters (Carretta et al., 2016). The species 
prefers deeper waters, ranging from 324 m to 4,400 m, with most 
sightings between 500 m and 3,000 m (Baird 2016). Although there are no 
records near the proposed project area, sightings have been reported 
for the Azores (OBIS 2017). Short-finned pilot whales could be 
encountered in the proposed project area.

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. Long-finned pilot whales are commonly sighted off 
Newfoundland and Labrador (DFO Sightings Database 2017; OIBS 2017); 
although sightings have been reported year-round, most have occurred 
during July and August (DFO Sightings Database 2017). There are 
numerous records near the deep waters of the proposed project area, 
including sightings near SIO's proposed Survey Area 5 and near the end 
of the seismic transect heading south of Area 5, and on and east of the 
Flemish Cap (OBIS 2017). Long-finned pilot whales were also sighted 
~520 km north of Survey Area 1 during the summer 2004 seismic survey by 
L-DEO (Haley and Koski 2004). The long-finned pilot whale could be 
encountered in the proposed study area.

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. Based on 
modeling by Mannocci et al. (2017), densities are expected to be low 
throughout the deep offshore waters of the western North Atlantic. 
However, in the OBIS database, there are records throughout the North 
Atlantic, including in offshore waters near the proposed project area 
between SIO's proposed survey transects at 49.3[deg] N, 42.7[deg] W; 
near Survey Areas 2, 3, and 4; near Sites 558 and 563; and west of 
Survey Area 1 near the seismic transect (OBIS 2017). Bottlenose 
dolphins were sighted ~500 km north of Survey Area 1 during the summer 
2004 seismic survey by L-DEO (Haley and Koski 2004). They have also 
been reported in the Azores (Morato et al. 2008; Silva et al. 2014; 
OBIS 2017). Bottlenose dolphins could 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

[[Page 18671]]

pelagic, although they occur close to shore where water near the coast 
is deep (Jefferson et al. 2015). One sighting was made in May 2012 in 
the proposed project area at 36.3[deg] N, 53.3[deg] W north of the 
southern-most seismic transect (OBIS 2017). Pantropical spotted 
dolphins could be encountered in the proposed project area.

Atlantic Spotted Dolphin

    Atlantic spotted dolphins are distributed in tropical and warm 
temperate waters of the western North Atlantic (Leatherwood et al., 
1976). Based on density modeling by Mannocci et al. (2017), Atlantic 
spotted dolphins occur throughout the western North Atlantic up to 
~45[deg] N, with slightly higher densities along 40[deg] N and ~32[deg] 
N. There are sighting records near SIO's proposed Survey Area 2, and 
between the Grand Banks and the southern-most seismic transect (OBIS 
2017). One sighting was made at 34.0[deg] N, 51.7[deg] W just to the 
northwest of Survey Area 1 during the spring 2013 L-DEO seismic survey 
in the Mid-Atlantic (Milne et al. 2013). Atlantic spotted dolphins were 
also sighted ~520 km north of Survey Area 1 during the summer 2004 
seismic survey by L-DEO (Haley and Koski 2004). Sightings have also 
been made near the Azores, including during spring and summer (Morato 
et al. 2008; Ryan et al. 2013; Silva et al. 2014; OBIS 2017). Atlantic 
spotted dolphins could be encountered in the proposed project area.

Striped Dolphin

    Striped dolphins are found in tropical to warm-temperate waters 
throughout the world (Carretta et al., 2016). 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). Based on density 
modeling by Mannocci et al. (2017) for the western North Atlantic, 
higher densities are expected in offshore waters north of ~38[deg] N, 
with the lowest densities south of ~30[deg] N. There are sighting 
records for the deep offshore waters between the coast of Canada and 
the Mid-Atlantic Ridge for May through August, including near SIO's 
proposed Survey Areas 2 and 3 (OBIS 2017). Sightings were also made in 
June 2004 along the Mid-Atlantic Ridge between 41[deg] and 49[deg] N 
(Doks[aelig]ter et al. 2008). Striped dolphins also occur in the Azores 
(Ryan et al. 2013; Silva et al. 2014; OBIS 2017). Striped dolphins 
could be encountered in the proposed project area.

Common Dolphin

    The common dolphin may be one of the most widely distributed 
species of cetaceans, as it is found world-wide in temperate and 
subtropical seas. 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). Based on density modeling by Mannocci et al. 
(2017) for the western North Atlantic, higher densities occur in 
offshore areas north of ~40[deg] N; very low densities are expected 
south of 40[deg] N. There are records throughout the North Atlantic, 
including sightings on the shelf and offshore of Newfoundland and the 
deep waters of the proposed project area (OBIS 2017). There are 
sighting records just south of SIO's proposed Survey Area 5 along the 
seismic transect and near Survey Areas 1-4 (OBIS 2017). There are 
numerous records along the Mid-Atlantic Ridge between 35[deg] and 
52[deg] N (Doks[aelig]ter et al. 2008; OBIS 2017). Common dolphins also 
occur in the Azores (Morato et al. 2008; Ryan et al. 2013; Silva et al. 
2014; OBIS 2017). Common dolphins could be encountered in the proposed 
project area.

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. Sighting 
records exist within or near the proposed project area, including near 
SIO's proposed Survey Areas 5 and 6, along the seismic transect heading 
southwest of Survey Area 6, near Survey Areas 3 and 4, Site 563, and 
north of Survey Area 1 (OBIS 2017). There are also several records 
along the Mid-Atlantic Ridge between 35[deg] and 60[deg] N 
(Doks[aelig]ter et al. 2008; OBIS 2017). Atlantic white-sided dolphins 
are likely to be encountered in the proposed project area during June-
July.

White-Beaked Dolphin

    The white-beaked dolphin is found in waters from southern New 
England to southern Greenland and Davis Straits (Leatherwood et al. 
1976; CETAP 1982), across the Atlantic to the Barents Sea and south to 
at least Portugal (Reeves et al. 1999). It appears to prefer deep 
waters along the outer shelf and slope, but can also occur in shallow 
areas and far offshore (Jefferson et al. 2015). One sighting of white-
beaked dolphin was made in the deep waters off Newfoundland, southwest 
of SIO's proposed Survey Area 6 near the proposed seismic transect, 
during July 2012 (Ryan et al. 2013). Another sighting was made near the 
proposed seismic transect southwest of Survey Area 5 at 50.1[deg] N, 
40.8[deg] W during March 2011 (OBIS 2017). White-beaked dolphins were 
observed on the Mid-Atlantic Ridge at 56.4[deg] N during June 2004 
(Skov et al. 2004). White-beaked dolphins could be encountered in the 
proposed project area during June-July.

Risso's Dolphin

    Risso's dolphins are found in tropical to warm-temperate waters 
(Carretta et al., 2016). The species occurs from coastal to deep water 
but is most often found in depths greater than 3,000 m with the highest 
sighting rate in depths greater than 4,500 m (Baird 2016). It primarily 
occurs between 60[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 is one sighting record near 
SIO's proposed Survey Area 4, just north of the end of the proposed 
seismic transect; and one sighting has been reported near Survey Area 2 
(OBIS 2017). There are numerous records for the Azores (Silva et al. 
2014; OBIS 2017). Risso's dolphin could be encountered in the proposed 
project area during June-July.

Harbor Porpoise

    The harbor porpoise inhabits temperate, subarctic, and arctic 
waters. It is typically found in shallow water (<100 m) nearshore, but 
it is occasionally sighted in deeper offshore water (Jefferson et al. 
2015). In the western North Atlantic, it occurs from the southeastern 
United States to Baffin Island; in the eastern North Atlantic 
(Jefferson et al. 2015). The harbor porpoise is generally considered 
uncommon in the offshore regions of the proposed project area, although 
sightings have been made along the outer shelf of Newfoundland and the 
Flemish Cap (DFO Sightings Database 2017; OBIS 2017). Mannocci et al. 
(2017) reported relatively high densities in offshore waters north of 
~40[deg] N; very

[[Page 18672]]

low densities are expected to occur south of ~38[deg] N. Harbor 
porpoises have been sighted in the Azores from May through September 
(OBIS 2017). Given their preference for coastal waters, harbor 
porpoises are expected to be uncommon near the proposed survey area.

Ringed Seal

    Ringed seals have a circumpolar distribution and are found in all 
seasonally ice-covered seas of the Northern Hemisphere as well as in 
certain freshwater lakes (King 1983). The subspecies P.h. hispida 
(Arctic ringed seal) occurs in the Northwest Atlantic Ocean. The 
southern range of the ringed seal extends to the coasts of Labrador and 
northern Newfoundland, where it most commonly occurs from November to 
January (Stenson 1994). As the range of this species includes the 
waters off southern Greenland and the Labrador Sea, it could be 
encountered in the proposed project area, but ringed seals are likely 
to be rare within and near the proposed project area.

Harp Seal

    The harp seal occurs throughout much of the North Atlantic and 
Arctic Oceans (Ronald and Healey 1981; Lavigne and Kovacs 1988). Harp 
seals are highly migratory (Sergeant 1965; Stenson and Sjare 1997). 
Breeding occurs at different times for each stock between late February 
and April. Adults then assemble on suitable pack ice to undergo the 
annual molt. The migration then continues north to Arctic summer 
feeding grounds. Harp seals have mainly been sighted on the shelf off 
Newfoundland, but there are no sightings in the OBIS database for the 
proposed project area (OBIS 2017). Harp seals are likely to be rare 
within and near the proposed project area during June-July.

Hooded Seal

    The hooded seal occurs throughout much of the North Atlantic and 
Arctic Oceans (King 1983) preferring deeper water and occurring farther 
offshore than harp seals (Sergeant 1976a; Campbell 1987; Lavigne and 
Kovacs 1988; Stenson et al. 1996). Hooded seals remain on the 
Newfoundland continental shelf during winter/spring (Stenson et al. 
1996) and breeding occurs in March. Hooded seals have been reported in 
shelf and offshore waters of Newfoundland throughout the year, 
including west of Survey Area 6 and near the seismic transect southwest 
of SIO's proposed Survey Area 6, during summer (Stenson and Kavanagh 
1994; Andersen et al. 2009, 2012). Vagrants, especially juveniles, have 
been reported in the Azores and off northwestern Africa (Jefferson et 
al. 2015). However, there are no sightings in the OBIS database for the 
proposed project area (OBIS 2017). Hooded seals are likely to be rare 
within and near the proposed project area during June-July.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et 
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect 
this, Southall et al. (2007) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2016) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 dB 
threshold from the normalized composite audiograms, with the exception 
for lower limits for low-frequency cetaceans where the lower bound was 
deemed to be biologically implausible and the lower bound from Southall 
et al. (2007) retained. The functional groups and the associated 
frequencies are indicated below (note that these frequency ranges 
correspond to the range for the composite group, with the entire range 
not necessarily reflecting the capabilities of every species within 
that group):
     Low-frequency cetaceans (mysticetes): Generalized hearing 
is estimated to occur between approximately 7 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; and
     Pinnipeds in water; Phocidae (true seals): Generalized 
hearing is estimated to occur between approximately 50 Hz to 86 kH.
    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. 
Thirty-three marine mammal species (thirty cetacean and three pinniped 
(all phocid) species) have the reasonable potential to co-occur with 
the proposed survey activities. Please refer to Table 2. Of the 
cetacean species that may be present, six are classified as low-
frequency cetaceans (i.e., all mysticete species), twenty-two are 
classified as mid-frequency cetaceans (i.e., all delphinid species, 
beaked whales, and the sperm whale), and three are classified as a 
high-frequency cetaceans (i.e., harbor porpoise, pygmy and dwarf sperm 
whales).

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

[[Page 18673]]

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 decibel (dB). A sound pressure 
level (SPL) in dB is described as the ratio between a measured pressure 
and a reference pressure (for underwater sound, this is 1 microPascal 
([mu]Pa)) and is a logarithmic unit that accounts for large variations 
in amplitude; therefore, a relatively small change in dB corresponds to 
large changes in sound pressure. The source level (SL) represents the 
SPL referenced at a distance of 1 m from the source (referenced to 1 
[mu]Pa) while the received level is the SPL at the listener's position 
(referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they may be accounted for in the summation of 
pressure levels (Hastings and Popper, 2005). This measurement is often 
used in the context of discussing behavioral effects, in part because 
behavioral effects, which often result from auditory cues, may be 
better expressed through averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa\2\-s) 
represents the total energy contained within a pulse and considers both 
intensity and duration of exposure. Peak sound pressure (also referred 
to as zero-to-peak sound pressure or 0-p) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source and is represented in the same units as the rms sound pressure. 
Another common metric is peak-to-peak sound pressure (pk-pk), which is 
the algebraic difference between the peak positive and peak negative 
sound pressures. Peak-to-peak pressure is typically approximately 6 dB 
higher than peak pressure (Southall et al., 2007).
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as 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

[[Page 18674]]

pressure to a maximal pressure value followed by a rapid decay period 
that may include a period of diminishing, oscillating maximal and 
minimal pressures, and generally have an increased capacity to induce 
physical injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or non-continuous (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems (such as 
those used by the U.S. Navy). The duration of such sounds, as received 
at a distance, can be greatly extended in a highly reverberant 
environment.
    Airgun arrays produce pulsed signals with energy in a frequency 
range from about 10-2,000 Hz, with most energy radiated at frequencies 
below 200 Hz. The amplitude of the acoustic wave emitted from the 
source is equal in all directions (i.e., omnidirectional), but airgun 
arrays do possess some directionality due to different phase delays 
between guns in different directions. Airgun arrays are typically tuned 
to maximize functionality for data acquisition purposes, meaning that 
sound transmitted in horizontal directions and at higher frequencies is 
minimized to the extent possible.
    As described above, a MBES and a SBP would also be operated from 
the Atlantis continuously throughout the survey, but not during 
transits to and from the project area. Due to the lower source level of 
the SBP relative to the Atlantis's airgun array, the sounds from the 
SBP are expected to be effectively subsumed by the sounds from the 
airgun array. Thus, any marine mammal that was exposed to sounds from 
the SBP would already have been exposed to sounds from the airgun 
array, which are expected to propagate further in the water. As such, 
the SBP is not expected to result in the take of any marine mammal that 
has not already been taken by the sounds from the airgun array, and 
therefore we do not consider noise from the SBP further in this 
analysis. Each ping emitted by the MBES consists of four successive 
fan-shaped transmissions, each ensonifying a sector that extends 1[deg] 
fore-aft. Given the movement and speed of the vessel, the intermittent 
and narrow downward-directed nature of the sounds emitted by the MBES 
would result in no more than one or two brief ping exposures of any 
individual marine mammal, if any exposure were to occur. Thus, we 
conclude that the likelihood of marine mammal take resulting from MBES 
exposure is discountable and therefore we do not consider noise from 
the MBES 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

[[Page 18675]]

bounds of physiological variability and tolerance and does not 
represent physical injury (e.g., Ward, 1997). Therefore, NMFS does not 
consider TTS to constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al. 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulse sounds (such as airgun pulses as 
received close to the source) are at least 6 dB higher than the TTS 
threshold on a peak-pressure basis and PTS cumulative sound exposure 
level (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; 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

[[Page 18676]]

marine mammals have showed pronounced behavioral reactions, including 
avoidance of loud sound sources (Ridgway et al., 1997). Observed 
responses of wild marine mammals to loud pulsed sound sources 
(typically seismic airguns or acoustic harassment devices) have been 
varied but often consist of avoidance behavior or other behavioral 
changes suggesting discomfort (Morton and Symonds, 2002; see also 
Richardson et al., 1995; Nowacek et al., 2007). However, many 
delphinids approach acoustic source vessels with no apparent discomfort 
or obvious behavioral change (e.g., Barkaszi et al., 2012).
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely, and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark 2000; Ng and Leung 2003; Nowacek et al. 2004; Goldbogen et 
al. 2013). Variations in dive behavior may reflect interruptions in 
biologically significant activities (e.g., foraging) or they may be of 
little biological significance. The impact of an alteration to dive 
behavior resulting from an acoustic exposure depends on what the animal 
is doing at the time of the exposure and the type and magnitude of the 
response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al. 
2001; Nowacek et al. 2004; Madsen et al. 2006; Yazvenko et al. 2007). A 
determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Visual tracking, passive acoustic monitoring, and movement 
recording tags were used to quantify sperm whale behavior prior to, 
during, and following exposure to airgun arrays at received levels in 
the range 140-160 dB at distances of 7-13 km, following a phase-in of 
sound intensity and full array exposures at 1-13 km (Madsen et al., 
2006; Miller et al., 2009). Sperm whales did not exhibit horizontal 
avoidance behavior at the surface. However, foraging behavior may have 
been affected. The sperm whales exhibited 19 percent less vocal (buzz) 
rate during full exposure relative to post exposure, and the whale that 
was approached most closely had an extended resting period and did not 
resume foraging until the airguns had ceased firing. The remaining 
whales continued to execute foraging dives throughout exposure; 
however, swimming movements during foraging dives were six percent 
lower during exposure than control periods (Miller et al., 2009). These 
data raise concerns that seismic surveys may impact foraging behavior 
in sperm whales, although more data are required to understand whether 
the differences were due to exposure or natural variation in sperm 
whale behavior (Miller et al., 2009).
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that 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

[[Page 18677]]

authors hypothesize that fin whale acoustic communication is modified 
to compensate for increased background noise and that a sensitization 
process may play a role in the observed temporary displacement.
    Seismic pulses at average received levels of 131 dB re 1 
[micro]Pa\2\-s caused blue whales to increase call production (Di Iorio 
and Clark, 2010). In contrast, McDonald et al. (1995) tracked a blue 
whale with seafloor seismometers and reported that it stopped 
vocalizing and changed its travel direction at a range of 10 km from 
the acoustic source vessel (estimated received level 143 dB pk-pk). 
Blackwell et al. (2013) found that bowhead whale call rates dropped 
significantly at onset of airgun use at sites with a median distance of 
41-45 km from the survey. Blackwell et al. (2015) expanded this 
analysis to show that whales actually increased calling rates as soon 
as airgun signals were detectable before ultimately decreasing calling 
rates at higher received levels (i.e., 10-minute SELcum of 
~127 dB). Overall, these results suggest that bowhead whales may adjust 
their vocal output in an effort to compensate for noise before ceasing 
vocalization effort and ultimately deflecting from the acoustic source 
(Blackwell et al., 2013, 2015). These studies demonstrate that even low 
levels of noise received far from the source can induce changes in 
vocalization and/or behavior for mysticetes.
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Humpback whales showed avoidance behavior in the presence of an 
active seismic array during observational studies and controlled 
exposure experiments in western Australia (McCauley et al., 2000). 
Avoidance may be short-term, with animals returning to the area once 
the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; Stone et 
al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). Longer-term 
displacement is possible, however, which may lead to changes in 
abundance or distribution patterns of the affected species in the 
affected region if habituation to the presence of the sound does not 
occur (e.g., Bejder et al., 2006; Teilmann et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, marine mammal strandings 
(Evans and England, 2001). However, it should be noted that response to 
a perceived predator does not necessarily invoke flight (Ford and 
Reeves, 2008), and whether individuals are solitary or in groups may 
influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil 1997; Fritz et al. 2002; Purser and Radford 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch 1992; Daan et al. 1996; Bradshaw et al. 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a five-day period did not cause any 
sleep deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent 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).

[[Page 18678]]

Increases in the circulation of glucocorticoids are also equated with 
stress (Romano et al. 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficiently to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    4. Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al., 1995; Erbe et al., 
2016). Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher intensity, and may occur whether the sound is natural (e.g., 
snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g., 
shipping, sonar, seismic exploration) in origin. The ability of a noise 
source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is man-made, it may be considered harassment 
when disrupting or altering critical behaviors. It is important to 
distinguish TTS and PTS, which persist after the sound exposure, from 
masking, which occurs during the sound exposure. Because masking 
(without resulting in TS) is not associated with abnormal physiological 
function, it is not considered a physiological effect, but rather a 
potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al. 2000; 
Foote et al. 2004; Parks et al. 2007; Di Iorio and Clark 2009; Holt et 
al. 2009). Masking can be reduced in situations where the signal and 
noise come from different directions (Richardson et al. 1995), through 
amplitude modulation of the signal, or through other compensatory 
behaviors (Houser and Moore 2014). Masking can be tested directly in 
captive species (e.g., Erbe 2008), but in wild 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

[[Page 18679]]

whales at a given speed, showing that the greatest rate of change in 
the probability of a lethal injury to a large whale as a function of 
vessel speed occurs between 8.6 and 15 kt. The chances of a lethal 
injury decline from approximately 80 percent at 15 kt to approximately 
20 percent at 8.6 kt. At speeds below 11.8 kt, the chances of lethal 
injury drop below 50 percent, while the probability asymptotically 
increases toward one hundred percent above 15 kt.
    The Atlantis would travel at a speed of either 5 kt (9.3 km/hour) 
or 8 kt (14.8 km/hour) 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 traveling at low 
speed (5.5 kt) while conducting mapping surveys off the central 
California coast struck and killed a blue whale in 2009. The State of 
California determined that the whale had suddenly and unexpectedly 
surfaced beneath the hull, with the result that the propeller severed 
the whale's vertebrae, and that this was an unavoidable event. This 
strike represents the only such incident in approximately 540,000 hours 
of similar coastal mapping activity (p = 1.9 x 10-6; 95% CI 
= 0-5.5 x 10-6; NMFS, 2013b). In addition, a research vessel 
reported a fatal strike in 2011 of a dolphin in the Atlantic, 
demonstrating that it is possible for strikes involving smaller 
cetaceans to occur. In that case, the incident report indicated that an 
animal apparently was struck by the vessel's propeller as it was 
intentionally swimming near the vessel. While indicative of the type of 
unusual events that cannot be ruled out, neither of these instances 
represents a circumstance that would be considered reasonably 
foreseeable or that would be considered preventable.
    Although the likelihood of the vessel striking a marine mammal is 
low, we require a robust ship strike avoidance protocol (see ``Proposed 
Mitigation''), which we believe eliminates any foreseeable risk of ship 
strike. We anticipate that vessel collisions involving a seismic data 
acquisition vessel towing gear, while not impossible, represent 
unlikely, unpredictable events for which there are no preventive 
measures. Given the required mitigation measures, the relatively slow 
speed of the vessel towing gear, the presence of bridge crew watching 
for obstacles at all times (including marine mammals), the presence of 
marine mammal observers, and the short duration of the survey (25 
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-mm mesh screen. All other trash and debris must

[[Page 18680]]

be returned to shore for proper disposal with municipal and solid 
waste. Some personal items may be accidentally lost overboard. However, 
U.S. Coast Guard and Environmental Protection Act regulations require 
operators to become proactive in avoiding accidental loss of solid 
waste items by developing waste management plans, posting informational 
placards, manifesting trash sent to shore, and using special 
precautions such as covering outside trash bins to prevent accidental 
loss of solid waste. There are no meaningful entanglement risks posed 
by the described activity, and entanglement risks are not discussed 
further in this document.
    Marine mammals could be affected by accidentally spilled diesel 
fuel from a vessel associated with proposed survey activities. 
Quantities of diesel fuel on the sea surface may affect marine mammals 
through various pathways: Surface contact of the fuel with skin and 
other mucous membranes, inhalation of concentrated petroleum vapors, or 
ingestion of the fuel (direct ingestion or by the ingestion of oiled 
prey) (e.g., Geraci and St. Aubin, 1980, 1985, 1990). However, the 
likelihood of a fuel spill during any particular geophysical survey is 
considered to be remote, and the potential for impacts to marine 
mammals would depend greatly on the size and location of a spill and 
meteorological conditions at the time of the spill. Spilled fuel would 
rapidly spread to a layer of varying thickness and break up into narrow 
bands or windrows parallel to the wind direction. The rate at which the 
fuel spreads would be determined by the prevailing conditions such as 
temperature, water currents, tidal streams, and wind speeds. Lighter, 
volatile components of the fuel would evaporate to the atmosphere 
almost completely in a few days. Evaporation rate may increase as the 
fuel spreads because of the increased surface area of the slick. 
Rougher seas, high wind speeds, and high temperatures also tend to 
increase the rate of evaporation and the proportion of fuel lost by 
this process (Scholz et al., 1999). We do not anticipate potentially 
meaningful effects to marine mammals as a result of any contaminant 
spill resulting from the proposed survey activities, and contaminant 
spills are not discussed further in this document.

Anticipated Effects on Marine Mammal Habitat

    Effects to Prey--Marine mammal prey varies by species, season, and 
location and, for some, is not well documented. Fish react to sounds 
which are especially strong and/or intermittent low-frequency sounds. 
Short duration, sharp sounds can cause overt or subtle changes in fish 
behavior and local distribution. Hastings and Popper (2005) identified 
several studies that suggest fish may relocate to avoid certain areas 
of sound energy. Additional studies have documented effects of pulsed 
sound on fish, although several are based on studies in support of 
construction projects (e.g., Scholik and Yan 2001, 2002; Popper and 
Hastings 2009). Sound pulses at received levels of 160 dB may cause 
subtle changes in fish behavior. SPLs of 180 dB may cause noticeable 
changes in behavior (Pearson et al. 1992; Skalski et al. 1992). SPLs of 
sufficient strength have been known to cause injury to fish and fish 
mortality. The most likely impact to fish from survey activities at the 
project area would be temporary avoidance of the area. The duration of 
fish avoidance of a given area after survey effort stops is unknown, 
but a rapid return to normal recruitment, distribution and behavior is 
anticipated.
    Information on seismic airgun impacts to zooplankton, which 
represent an important prey type for mysticetes, is limited. However, 
McCauley et al. (2017) reported that experimental exposure to a pulse 
from a 150 in\3\ airgun decreased zooplankton abundance when compared 
with controls, as measured by sonar and net tows, and caused a two- to 
threefold increase in dead adult and larval zooplankton. Although no 
adult krill were present, the study found that all larval krill were 
killed after air gun passage. Impacts were observed out to the maximum 
1.2 km range sampled.
    In general, impacts to marine mammal prey are expected to be 
limited due to the relatively small temporal and spatial overlap 
between the proposed survey and any areas used by marine mammal prey 
species. The proposed survey would occur over a relatively short time 
period (25 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

[[Page 18681]]

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 primarily be by Level B harassment, as use 
of the seismic airguns have the potential to result in disruption of 
behavioral patterns for individual marine mammals. There is also some 
potential for auditory injury (Level A harassment) to result, primarily 
for high frequency cetaceans. Auditory injury is unlikely to occur for 
low- and mid-frequency cetaceans given very small modeled zones of 
injury for those species. The proposed mitigation and monitoring 
measures are expected to minimize the severity of such taking to the 
extent practicable. As described previously, no mortality is 
anticipated or proposed to be authorized for this activity. Below we 
describe how the take is estimated.
    Described in the most basic way, we estimate take by considering: 
(1) Acoustic thresholds above which NMFS believes the best available 
science indicates marine mammals will be behaviorally harassed or incur 
some degree of permanent hearing impairment; (2) the area or volume of 
water that will be ensonified above these levels in a day; (3) the 
density or occurrence of marine mammals within these ensonified areas; 
and (4) and the number of days of activities. Below, we describe these 
components in more detail and present the exposure estimate and 
associated numbers of take proposed for authorization.

Acoustic Thresholds

    Using the best available science, NMFS has developed acoustic 
thresholds that identify the received level of underwater sound above 
which exposed marine mammals would be reasonably expected to be 
behaviorally harassed (equated to Level B harassment) or to incur PTS 
of some degree (equated to Level A harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al. 2011). Based on the best available science and the 
practical need to use a threshold based on a factor that is both 
predictable and measurable for most activities, NMFS uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS predicts that marine mammals are likely to 
be behaviorally harassed in a manner we consider to fall under Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g. 
vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms) 
for non-explosive impulsive (e.g., seismic airguns) or intermittent 
(e.g., scientific sonar) sources. SIO's proposed activity includes the 
use of impulsive seismic sources. Therefore, the 160 dB re 1 [mu]Pa 
(rms) criteria is applicable for analysis of level B harassment.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (NMFS, 2016) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). As 
described above, SIO'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: 
https://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm.

            Table 4--Thresholds Identifying the Onset of Permanent Threshold Shift in Marine Mammals
----------------------------------------------------------------------------------------------------------------
                                                                   PTS Onset thresholds
              Hearing group              -----------------------------------------------------------------------
                                                    Impulsive *                        Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans............  Lpk,flat: 219 dB; LE,LF,24h:     LE,LF,24h: 199 dB.
                                           183 dB.
Mid-Frequency (MF) Cetaceans............  Lpk,flat: 230 dB; LE,MF,24h:     LE,MF,24h: 198 dB.
                                           185 dB.
High-Frequency (HF) Cetaceans...........  Lpk,flat: 202 dB; LE,HF,24h:     LE,HF,24h: 173 dB.
                                           155 dB.
Phocid Pinnipeds (PW) (Underwater)......  Lpk,flat: 218 dB; LE,PW,24h:     LE,PW,24h: 201 dB.
                                           185 dB.
Otariid Pinnipeds (OW) (Underwater).....  Lpk,flat: 232 dB; LE,OW,24h:     LE,OW,24h: 219 dB.
                                           203 dB.
----------------------------------------------------------------------------------------------------------------
Note: * Dual metric acoustic thresholds for impulsive sounds: Use whichever results in the largest isopleth for
  calculating PTS onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure level
  thresholds associated with impulsive sounds, these thresholds should also be considered.
Note: Peak sound pressure (Lpk) has a reference value of 1 [mu]Pa, and cumulative sound exposure level (LE) has
  a reference value of 1[mu]Pa2s. In this Table, thresholds are abbreviated to reflect American National
  Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as incorporating
  frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript ``flat'' is
  being included to indicate peak sound pressure should be flat weighted or unweighted within the generalized
  hearing range. The subscript associated with cumulative sound exposure level thresholds indicates the
  designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds) and
  that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could be
  exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible, it
  is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.


[[Page 18682]]

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into estimating the area ensonified above the 
acoustic thresholds.
    The proposed survey would entail the use of a 2-airgun array with a 
total discharge of 90 in\3\ at a tow depth of 2-4 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. Received 
sound levels were predicted by LDEO's model (Diebold et al. 2010) as a 
function of distance from the airgun array. The LDEO modeling approach 
uses ray tracing for the direct wave traveling from the array to the 
receiver and its associated source ghost (reflection at the air-water 
interface in the vicinity of the array), in a constant-velocity half-
space (infinite homogeneous ocean layer unbounded by a seafloor). In 
addition, propagation measurements of pulses from a 36-airgun array at 
a tow depth of 6 m have been reported in deep water (~1,600 m), 
intermediate water depth on the slope (~600-1100 m), and shallow water 
(~50 m) in the Gulf of Mexico in 2007-2008 (Tolstoy et al. 2009; 
Diebold et al. 2010). The estimated distances to Level B harassment 
isopleths for the two proposed configurations of the Atlantis airgun 
array are shown in Table 5.

  Table 5--Predicted Radial Distances From R/V Atlantis 90 in3 Seismic
    Source to Isopleth Corresponding to Level B Harassment Threshold
------------------------------------------------------------------------
                                                               Predicted
                                                               distance
                                                                  to
                     Array configuration                       threshold
                                                              (160 dB re
                                                               1 [mu]Pa)
                                                                  (m)
------------------------------------------------------------------------
2 m airgun separation.......................................         578
8 m airgun separation.......................................         539
------------------------------------------------------------------------

    For modeling of radial distances to predicted isopleths 
corresponding to harassment thresholds in deep water (>1,000 m), LDEO 
used the deep-water radii for various Sound Exposure Levels obtained 
from LDEO model results down to a maximum water depth of 2,000 m (see 
Figures 2 and 3 in the IHA application). LDEO's modeling methodology is 
described in greater detail in the IHA application (LGL, 20178) and we 
refer to the reader to that document rather than repeating it here.
    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal functional hearing groups (Table 3), were 
calculated based on modeling performed by LDEO using the Nucleus 
software program and the NMFS User Spreadsheet, described below. The 
updated acoustic thresholds for impulsive sounds (such as airguns) 
contained in the Technical Guidance (NMFS, 2016) were presented as dual 
metric acoustic thresholds using both SELcum and peak sound 
pressure level metrics. As dual metrics, NMFS considers onset of PTS 
(Level A harassment) to have occurred when either one of the two 
metrics is exceeded (i.e., metric resulting in the largest isopleth). 
The SELcum metric considers both level and duration of 
exposure, as well as auditory weighting functions by marine mammal 
hearing group. In recognition of the fact that the requirement to 
calculate Level A harassment ensonified areas could be more technically 
challenging to predict due to the duration component and the use of 
weighting functions in the new SELcum thresholds, NMFS 
developed an optional User Spreadsheet that includes 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 Atlantis 
airgun array were derived from calculating the modified farfield 
signature (Table 6). The farfield signature is often used as a 
theoretical representation of the source level. To compute the farfield 
signature, the source level is estimated at a large distance below the 
array (e.g., 9 km), and this level is back projected mathematically to 
a notional distance of 1 m from the array's geometrical center. 
However, when the source is an array of multiple airguns separated in 
space, the source level from the theoretical farfield signature is not 
necessarily the best measurement of the source level that is physically 
achieved at the source (Tolstoy et al. 2009). Near the source (at short 
ranges, distances <1 km), the pulses of sound pressure from each 
individual airgun in the source array do not stack constructively, as 
they do for the theoretical farfield signature. The pulses from the 
different airguns spread out in time such that the source levels 
observed or modeled are the result of the summation of pulses from a 
few airguns, not the full array (Tolstoy et al. 2009). At larger 
distances, away from the source array center, sound pressure of all the 
airguns in the array stack coherently, but not within one time sample, 
resulting in smaller source levels (a few dB) than the source level 
derived from the farfield signature. Because the farfield signature 
does not take into account the array effect near the source and is 
calculated as a point source, the modified farfield signature is a more 
appropriate measure of the sound source level for distributed sound 
sources, such as airgun arrays. Though the array effect is not expected 
to be as pronounced in the case of a 2-airgun array as it would be with 
a larger airgun array, the modified farfield method is considered more 
appropriate than use of the theoretical farfield signature.

                    Table 6--Modeled Source Levels (dB) for R/V Atlantis 90 in3 Airgun Array
----------------------------------------------------------------------------------------------------------------
                                                    8-kt survey                     5-kt survey
                                                     with 8-m       8-kt survey      with 2-m       5-kt survey
                                                      airgun         with 8-m         airgun         with 2-m
            Functional hearing group                separation:       airgun        separation:       airgun
                                                   Peak SPLflat     separation:    Peak SPLflat     separation:
                                                                      SELcum                          SELcum
----------------------------------------------------------------------------------------------------------------
Low frequency cetaceans (Lpk,flat: 219 dB;                 228.8             207           232.8           206.7
 LE,LF,24h: 183 dB).............................
Mid frequency cetaceans (Lpk,flat: 230 dB;                   N/A           206.7           229.8           206.9
 LE,MF,24h: 185 dB).............................
High frequency cetaceans (Lpk,flat: 202 dB;                  233           207.6           232.9           207.2
 LE,HF,24h: 155 dB).............................
Phocid Pinnipeds (Underwater) (Lpk,flat: 218 dB;             230           206.7           232.8           206.9
 LE,HF,24h: 185 dB).............................
Otariid Pinnipeds (Underwater) (Lpk,flat: 232                N/A             203           225.6           207.4
 dB; LE,HF,24h: 203 dB).........................
----------------------------------------------------------------------------------------------------------------


[[Page 18683]]

    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 Atlantis'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 (for the 2 m airgun 
separation) and 5.14 m/second (for the 8 m airgun separation), and a 
shot interval of 12.15 seconds (for the 2 m airgun separation) and 9.72 
seconds (for the 8 m airgun separation) (LGL, 2018), potential radial 
distances to auditory injury zones were calculated for 
SELcum thresholds, for both array configurations. Inputs to 
the User Spreadsheet are shown in Table 6. Outputs from the User 
Spreadsheet in the form of estimated distances to Level A harassment 
isopleths are shown in Table 7. As described above, the larger distance 
of the dual criteria (SELcum or Peak SPLflat) is 
used for estimating takes by Level A harassment. The weighting 
functions used are shown in Table 3 of the IHA application.

 Table 7--Modeled Radial Distances (m) From R/V Atlantis 90 in3 Airgun Array to Isopleths Corresponding to Level
                                             A Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                                    8-kt survey                     5-kt survey
                                                     with 8-m       8-kt survey      with 2-m       5-kt survey
  Functional hearing group (Level A harassment        airgun         with 8-m         airgun         with 2-m
                   thresholds)                      separation:       airgun        separation:       airgun
                                                   Peak SPLflat     separation:    Peak SPLflat     separation:
                                                                      SELcum                          SELcum
----------------------------------------------------------------------------------------------------------------
Low frequency cetaceans (Lpk,flat: 219 dB;                  3.08             2.4            4.89             6.5
 LE,LF,24h: 183 dB).............................
Mid frequency cetaceans (Lpk,flat: 230 dB;                     0               0            0.98               0
 LE,MF,24h: 185 dB).............................
High frequency cetaceans (Lpk,flat: 202 dB;                34.84               0           34.62               0
 LE,HF,24h: 155 dB).............................
Phocid Pinnipeds (Underwater) (Lpk,flat: 218 dB;            4.02               0            5.51             0.1
 LE,HF,24h: 185 dB).............................
Otariid Pinnipeds (Underwater) (Lpk,flat: 232                  0               0            0.48               0
 dB; LE,HF,24h: 203 dB).........................
----------------------------------------------------------------------------------------------------------------

    Note that because of some of the assumptions included in the 
methods used, isopleths produced may be overestimates to some degree, 
which will ultimately result in some degree of overestimate of Level A 
take. However, these tools offer the best way to predict appropriate 
isopleths when more sophisticated 3D modeling methods are not 
available, and NMFS continues to develop ways to quantitatively refine 
these tools and will qualitatively address the output where 
appropriate. For mobile sources, such as the proposed seismic survey, 
the User Spreadsheet predicts the closest distance at which a 
stationary animal would not incur PTS if the sound source traveled by 
the animal in a straight line at a constant speed.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. The best available scientific information was considered 
in conducting marine mammal exposure estimates (the basis for 
estimating take). For all cetacean species, densities calculated by 
Mannocci et al. (2017) were used. These represent the most 
comprehensive and recent density data available for cetacean species in 
the survey area. Mannocci et al. (2017) modeled marine mammal densities 
using available line transect survey data and habitat-based covariates 
and extrapolated model predictions to unsurveyed regions, including the 
proposed survey area. The authors considered line transect surveys that 
used two or more protected species observers and met the assumptions of 
the distance sampling methodology as presented by Buckland et al. 
(2001), and included data from shipboard and aerial surveys conducted 
from 1992 to 2014 by multiple U.S. organizations (details provided in 
Roberts et al. (2016)). The data underlying the model predictions for 
the proposed survey area originated from shipboard survey data 
presented in Waring et al. (2008). To increase the success of model 
transferability to new regions, the authors considered biological 
covariates expected to be related directly to cetacean densities 
(Wenger & Olden, 2012), namely biomass and production of epipelagic 
micronekton and zooplankton predicted with the Spatial Ecosystem and 
Population DYnamics Model (SEAPODYM) (Lehodey et al. 2010). Zooplankton 
and epipelagic micronekton (i.e., squid, crustaceans, and fish) 
constitute potential prey for many of the cetaceans considered, in 
particular dolphins and mysticetes (Pauly et al. 1998), and all these 
covariates correlate with cetacean distributions (e.g., Ferguson et al. 
2006; Doniol-Valcroze et al. 2007; Lambert et al. 2014). There is some 
uncertainty related to the estimated density data and the assumptions 
used in their calculations, as with all density data estimates. 
However, the approach used is based on the best available data.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate. In order to estimate 
the number of marine mammals predicted to be exposed to sound levels 
that would result in Level B harassment or Level A harassment, radial 
distances to predicted isopleths corresponding to the Level A 
harassment and Level B harassment thresholds are calculated, as 
described above (Table 8). Those distances are then used to calculate 
the area(s) around the airgun array predicted to be ensonified to sound 
levels that exceed the Level A and Level B harassment thresholds. The 
areas estimated to be ensonified in a single day of the survey are then 
calculated, based on the areas predicted to be ensonified around the 
array and the estimated trackline distance traveled per day (Table 9). 
This number is then multiplied by the number of survey days (i.e., 7.5 
days for the 5-kt survey with 2-m airgun separation and 17.5 days for 
the 8-kt survey with 8-m airgun separation). The product is then 
multiplied by 1.25 to account for an additional 25 percent contingency 
for potential additional

[[Page 18684]]

seismic operations, as described above. This results in an estimate of 
the total areas (km\2\) expected to be ensonified to the Level A 
harassment and Level B harassment thresholds. For purposes of Level B 
take calculations, areas estimated to be ensonified to Level A 
harassment thresholds are subtracted from total areas estimated to be 
ensonified to Level B harassment thresholds in order to avoid double 
counting the animals taken (i.e., if an animal is taken by Level A 
harassment, it is not also counted as taken by Level B harassment). 
Areas estimated to be ensonified over the duration of the survey are 
shown in Table 10. The marine mammals predicted to occur within these 
respective areas, based on estimated densities, are assumed to be 
incidentally taken. Estimated takes for all marine mammal species are 
shown in Table 11.

                             Table 8--Distances (m) to Isopleths Corresponding to Level A and Level B Harassment Thresholds
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Level B                            Level A harassment threshold \1\
                                                            harassment   -------------------------------------------------------------------------------
                                                             threshold
                         Survey                          ----------------  Low frequency   Mid frequency  High frequency      Otariid         Phocid
                                                            All marine       cetaceans       cetaceans       cetaceans       pinnipeds       pinnipeds
                                                              mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
5-kt survey with 2-m airgun separation..................             539             6.5            0.98           34.62            5.51            0.48
8-kt survey with 8-m airgun separation..................             578            3.08               0           34.84            4.02               0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Level A ensonified areas are estimated based on the greater of the distances calculated to Level A isopleths using dual criteria (SELcum and peak
  PL).


                          Table 9--Areas (km2) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds per Day
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Level B                            Level A harassment threshold \1\
                                                            harassment   -------------------------------------------------------------------------------
                                                             threshold
                         Survey                          ----------------  Low frequency   Mid frequency  High frequency      Otariid         Phocid
                                                            All marine       cetaceans       cetaceans       cetaceans       pinnipeds       pinnipeds
                                                              mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
5-kt survey with 2-m airgun separation..................          240.68            2.90            0.44           15.40            2.45            0.21
8-kt survey with 8-m airgun separation..................          412.10            2.19               0           24.78            2.86               0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Level A ensonified areas are estimated based on the greater of the distances calculated to Level A isopleths using dual criteria (SELcum and peak
  PL).
Note: Estimated areas shown for single day do not include additional 25 percent contingency.


                  Table 10--Areas (km2) Estimated To Be Ensonified to Level A and Level B Harassment Thresholds Over Duration of Survey
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Level B                            Level A harassment threshold \1\
                                                            harassment   -------------------------------------------------------------------------------
                                                             threshold
                         Survey                          ----------------  Low frequency   Mid frequency  High frequency      Otariid         Phocid
                                                            All marine       cetaceans       cetaceans       cetaceans       pinnipeds       pinnipeds
                                                              mammals
--------------------------------------------------------------------------------------------------------------------------------------------------------
5-kt survey with 2-m airgun separation..................         2256.33           27.10            4.09          144.40           22.97             2.0
8-kt survey with 8-m airgun separation..................         9014.56           47.84               0          542.09           62.50               0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Level A ensonified areas are estimated based on the greater of the distances calculated to Level A isopleths using dual criteria (SELcum and peak
  PL).
Note: Estimated areas shown include additional 25 percent contingency.


                               Table 11--Numbers of Potential Incidental Take of Marine Mammals Proposed for Authorization
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                       Total proposed
                                     Density (#/      Estimated    Proposed Level     Estimated    Proposed Level  Total proposed  instances of takes as
             Species                1,000 km\2\)    Level A takes      A takes      Level B takes      B takes       Level A and    a percentage of SAR
                                                                                                                    Level B takes      abundance \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Humpback whale \2\...............              10               1               0             112             113             113  0.9 *.
Minke whale......................               4               0               0              45              45              45  0.2 *.
Bryde's whale....................             0.1               0               0               1               1               1  unknown.
Sei whale \2\....................              10               1               0             112             113             113  31.4.
Fin whale........................               8               1               0              89              90              90  2.6 *.
Blue whale.......................               0               0               0               0               1               1  0.2.
Sperm whale......................              40               0               0             451             451             451  19.7.
Cuvier's beaked whale \3\........              60               0               0             135             135             135  2.0.
Northern bottlenose whale \4\....             0.8               0               0               9               9               9  unknown.
True's beaked whale \3\..........              60               0               0             135             135             135  1.9.

[[Page 18685]]

 
Gervais beaked whale \3\.........              60               0               0             135             135             135  1.9.
Sowerby's beaked whale \3\.......              60               0               0             135             135             135  1.9.
Blainville's beaked whale \3\....              60               0               0             135             135             135  1.9.
Rough-toothed dolphin............               3               0               0              34              34              34  12.5.
Bottlenose dolphin...............              60               0               0             677             677             677  0.9.
Pantropical spotted dolphin......              10               0               0             113             113             113  3.4.
Atlantic spotted dolphin.........              40               0               0             451             451             451  1.0.
Striped dolphin..................              80               0               0             902             902             902  1.6.
Atlantic white-sided dolphin.....              60               0               0             677             677             677  1.4.
White-beaked dolphin.............               1               0               0              11              11              11  0.6.
Common dolphin...................             800               3               0            9014            9017            9017  5.2 *.
Risso's dolphin..................              20               0               0             226             226             226  1.2.
Pygmy killer whale \4 5\.........             1.5               0               0              17              17              17  unknown.
False killer whale...............               2               0               0              23              23              23  5.2.
Killer whale \4 6\...............             0.2               0               0               2               5               5  unknown.
Long-finned/short-finned Pilot                200               1               0            2253            2254            2254  8.3.
 whale \7\.
Pygmy/dwarf sperm whale..........             0.6               0               0               7               7               7  0.2.
Harbor porpoise..................              60              41              41             635             635             676  0.8.
Ringed seal \4\..................               0               0               0               0               1               1  unknown.
Hooded seal......................               0               0               0               0               1               1  <0.1.
Harp seal........................               0               0               0               0               1               1  <0.1.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ While we have in most cases provided comparisons of the proposed instances of takes as a percentage of SAR abundance as the best available
  information regarding population abundance, we note that these are likely underestimates of the relevant North Atlantic populations, as the proposed
  survey area is outside the U.S. EEZ. Asterisks denote that instances of takes are shown as a percentage of abundance as described by TNASS or NMFS
  Status Review, as described above.
\2\ We have determined Level A take of these species is not likely, therefore estimated Level A takes have been added to the number of Level B takes
  proposed for authorization.
\3\ Density value represents the value for all beaked whales combined. Requested take and take proposed for authorization based on proportion of all
  beaked whales expected to be taken (677 total estimated beaked whale takes divided by 5 species of beaked whales).
\4\ The population abundance for the species is unknown.
\5\ The density estimate for pygmy killer whales shown in Table 8 in the IHA application is incorrect; the correct density is 1.5 animals/km\2\ as shown
  here.
\6\ Proposed take number for killer whales has been increased from the calculated take to mean group size for the species. Source for mean group size is
  Waring et al. (2008).
\7\ Values for density, proposed take number, and percentage of population proposed for authorization are for short-finned and long-finned pilot whales
  combined.

    For some marine mammal species, we propose to authorize a different 
number of incidental takes than the number of incidental takes 
requested by SIO (see Table 8 in the IHA application for requested take 
numbers). For instance, SIO requested 1 take of a North Atlantic right 
whale and 3 takes of bowhead whales; however, we have determined the 
likelihood of the survey encountering these species is so low as to be 
discountable, therefore we do not propose to authorize takes of these 
species. Also, SIO requested Level A takes of humpback whales, sei 
whales, fin whales, common dolphins, and pilot whales; however, due to 
very small zones corresponding to Level A harassment for low-frequency 
and mid-frequency cetaceans (Table 7) we have determined the likelihood 
of Level A take occurring for species from these functional hearing 
groups is so low as to be discountable, therefore we do not propose to 
authorize Level A take of these species. Note that the Level A takes 
that were calculated for these species (humpback whales, sei whales, 
fin whales, common dolphins, and pilot whales) have been included in 
the proposed number of Level B takes. Finally, SIO requested 2,254 
takes of short-finned pilot whales and 2,254 takes of long-finned pilot 
whales (total 4,508 pilot whale takes requested); however, as Mannocci 
et al. (2017) presents one single density estimate for all pilot whales 
(the pilot whale ``guild''), a total of 2,254 takes of pilot whales 
were calculated as potentially taken by the proposed survey. Thus SIO's 
request take number is actually double the number of take that was 
calculated. We do not think doubling the take estimate is warranted, 
thus we propose to authorize a total of 2,254 takes of pilot whales 
(short-finned and long-finned pilot whales combined).
    Species With Take Estimates Less Than Mean Group Size: Using the 
approach described above to estimate take, the take estimate for killer 
whales was less than the average group size estimated for the species 
(Waring et al., 2008). Information on the social structure and life 
history of the species indicates it is common for the species to be 
encountered in groups. The results of

[[Page 18686]]

take calculations support the likelihood that SIO's survey may 
encounter and incidentally take the species, and we believe it is 
likely that the species may be encountered in groups; therefore it is 
reasonable to conservatively assume that one group of the species will 
be taken during the proposed survey. We therefore propose to authorize 
the take of the average (mean) group size for the species to account 
for the possibility that SIO's survey encounters a group of killer 
whales.
    Species With No Available Density Data: No density data were 
available for the blue whale; however, blue whales have been observed 
in the survey area (Waring et al., 2008), thus we determined there is a 
possibility that the proposed survey may encounter one blue whale and 
that one blue whale may be taken by Level B harassment by the proposed 
survey; we therefore propose to authorize one take of blue whale as 
requested by SIO. No density data were available for ringed seal, 
hooded seal or harp seal; however based on the ranges of these species 
we have determined it is possible they may be encountered and taken by 
Level B harassment by the proposed survey, therefore we propose to 
authorize one take of each species as requested by SIO.
    It should be noted that the proposed take numbers shown in Table 11 
are believed to be conservative for several reasons. First, in the 
calculations of estimated take, 25 percent has been added in the form 
of operational survey days (equivalent to adding 25 percent to the 
proposed line km to be surveyed) to account for the possibility of 
additional seismic operations associated with airgun testing, and 
repeat coverage of any areas where initial data quality is sub-
standard. Additionally, marine mammals would be expected to move away 
from a sound source that represents an aversive stimulus. However, the 
extent to which marine mammals would move away from the sound source is 
difficult to quantify and is therefore not accounted for in take 
estimates shown in Table 8.

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting such 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned) the likelihood of effective implementation (probability 
implemented as planned), and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    SIO has reviewed mitigation measures employed during seismic 
research surveys authorized by NMFS under previous incidental 
harassment authorizations, as well as recommended best practices in 
Richardson et al. (1995), Pierson et al. (1998), Weir and Dolman 
(2007), Nowacek et al. (2013), Wright (2014), and Wright and Cosentino 
(2015), and has incorporated a suite of proposed mitigation measures 
into their project description based on the above sources.
    To reduce the potential for disturbance from acoustic stimuli 
associated with the activities, SIO has proposed to implement the 
following mitigation measures for marine mammals:
    (1) Vessel-based visual mitigation monitoring;
    (2) Establishment of 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 SIO, NMFS has proposed the 
following mitigation measure: Establishment of a marine mammal buffer 
zone.
    PSO observations would take place during all daytime airgun 
operations and nighttime start ups (if applicable) of the airguns. If 
airguns are operating throughout the night, observations would begin 30 
minutes prior to sunrise. If airguns are operating after sunset, 
observations would continue until 30 minutes following sunset. 
Following a shutdown for any reason, observations would occur for at 
least 30 minutes prior to the planned start of airgun operations. 
Observations would also occur for 30 minutes after airgun operations 
cease for any reason. Observations would also be made during daytime 
periods when the Atlantis 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 EZ (as described 
below).
    During seismic operations, three visual PSOs would be based aboard 
the Atlantis. PSOs would be appointed by SIO with NMFS approval. During 
the majority of seismic operations, two PSOs would monitor for marine 
mammals around the seismic vessel. A minimum of one PSO must be on duty 
at all times when the array is active. PSO(s) would be on duty in 
shifts of duration no longer than 4 hours. Other crew would also be 
instructed to assist in detecting marine mammals and in implementing 
mitigation requirements (if practical). Before the start of the seismic 
survey, the crew would be given additional instruction in detecting 
marine mammals and implementing mitigation requirements.
    The Atlantis is a suitable platform from which PSOs would watch for 
marine mammals. Standard equipment for marine mammal observers would be 
7 x 50 reticule binoculars and optical range finders. At night, night-
vision equipment would be available. The observers would be in 
communication with ship's officers on the bridge and scientists in the 
vessel's operations laboratory, so they can advise promptly of the need 
for avoidance maneuvers or seismic source shutdown.
    The PSOs must have no tasks other than to conduct observational 
effort, record observational data, and communicate with and instruct 
relevant vessel crew with regard to the presence of marine mammals and 
mitigation requirements. PSO resumes would be provided to NMFS for 
approval. At least

[[Page 18687]]

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 vessel 
operator. 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 for the airgun 
array. The 100 m EZ would be based on radial distance from any element 
of the airgun array (rather than being based on the center of the array 
or around the vessel itself). With certain exceptions (described 
below), if a marine mammal appears within, enters, or appears on a 
course to enter this zone, the acoustic source would be shut down (see 
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 for all marine mammal hearing groups (Table 7) while also 
providing a consistent, reasonably observable zone within which PSOs 
would typically be able to conduct effective observational effort. In 
this case, the 100 m radial distance would also be expected to contain 
sound that would exceed the Level A harassment threshold based on sound 
exposure level (SELcum) criteria for all marine mammal 
hearing groups (Table 7). In the 2011 Programmatic Environmental Impact 
Statement for marine scientific research funded by the National Science 
Foundation or the U.S. Geological Survey (NSF-USGS 2011), Alternative B 
(the Preferred Alternative) conservatively applied a 100 m EZ for all 
low-energy acoustic sources in water depths >100 m, with low-energy 
acoustic sources defined as any towed acoustic source with a single or 
a pair of clustered airguns with individual volumes of <=250 in\3\. 
Thus the 100 m EZ proposed for this survey is consistent with the PEIS.
    Our intent in prescribing a standard 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 a 200 m buffer zone. During 
use of the acoustic source, occurrence of marine mammals within the 
buffer zone (but outside the EZ) would be communicated to the operator 
to prepare for potential shutdown of the acoustic source. The buffer 
zone is discussed further under Ramp Up Procedures below.

Shutdown Procedures

    If a marine mammal is detected outside the EZ but is likely to 
enter the EZ, the airguns would be shut down before the animal is 
within the EZ. Likewise, if a marine mammal is already within the EZ 
when first detected, the airguns would be shut down immediately.
    Following a shutdown, airgun activity would not resume until the 
marine mammal has cleared the 100 m EZ. The animal would be considered 
to have cleared the 100 m EZ if the following conditions have been met:
     It is visually observed to have departed the 100 m EZ, or
     it has not been seen within the 100 m EZ for 15 min in the 
case of small odontocetes, or
     it has not been seen within the 100 m EZ for 30 min in the 
case of mysticetes and large odontocetes, including sperm, pygmy sperm, 
and beaked whales.
    This shutdown requirement would be in place for all marine mammals, 
with the exception of small delphinoids under certain circumstances. As 
defined here, the small delphinoid group is intended to encompass those 
members of the Family Delphinidae most likely to voluntarily approach 
the source vessel for purposes of interacting with the vessel and/or 
airgun array (e.g., bow riding). This exception to the shutdown 
requirement would apply solely to specific genera of small dolphins--
Tursiops, Steno, Stenella, Lagenorhynchus and Delphinus--and would only 
apply if the animals were traveling, including approaching the vessel. 
If, for example, an animal or group of animals is stationary for some 
reason (e.g., feeding) and the source vessel approaches the animals, 
the shutdown requirement applies. An animal with sufficient incentive 
to remain in an area rather than avoid an otherwise aversive stimulus 
could either incur auditory injury or disruption of important behavior. 
If there is uncertainty regarding identification (i.e., whether the 
observed animal(s) belongs to the group described above) or whether the 
animals are traveling, the shutdown would be implemented.
    We propose this small delphinoid exception because shutdown 
requirements for small delphinoids under all circumstances represent 
practicability concerns without likely commensurate benefits for the 
animals in question. Small delphinoids are generally the most commonly 
observed marine mammals in the specific geographic region and would 
typically be the only marine mammals likely to intentionally approach 
the vessel. As described below, auditory injury is extremely unlikely 
to occur for mid-frequency cetaceans (e.g., delphinids), as this group 
is relatively insensitive to sound produced at the predominant 
frequencies in an airgun pulse while also having a relatively high 
threshold for the onset of auditory injury (i.e., permanent threshold 
shift). Please see ``Potential Effects of the Specified Activity on 
Marine Mammals'' above for further discussion of sound metrics and 
thresholds and marine mammal hearing.
    A large body of anecdotal evidence indicates that small delphinoids 
commonly approach vessels and/or towed arrays during active sound 
production for purposes of bow riding, with no apparent effect observed 
in those delphinoids (e.g., Barkaszi et al., 2012). The potential for 
increased shutdowns resulting from such a measure would require the 
Atlantis 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

[[Page 18688]]

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 system as well as some more severe behavioral reactions for 
any such animals in close proximity to the source vessel.
    At any distance, shutdown of the acoustic source would also be 
required upon observation of any of the following:
     A large whale (i.e., sperm whale or any baleen whale) with 
a calf; or
     an aggregation of large whales of any species (i.e., sperm 
whale or any baleen whale) that does not appear to be traveling (e.g., 
feeding, socializing, etc.).
    These would be the only two 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 would begin with the activation of 
one 45 in\3\ airgun, with the second 45 in\3\ airgun activated after 5 
minutes.
    At least two PSOs would be required to monitor during ramp-up. 
During ramp up, the PSOs would monitor the EZ, and if marine mammals 
were observed within the EZ or buffer zone, a shutdown would be 
implemented as though the full array were operational. If airguns have 
been shut down due to PSO detection of a marine mammal within or 
approaching the 100 m EZ, ramp-up would not be initiated until all 
marine mammals have cleared the EZ, during the day or night. Criteria 
for clearing the EZ would be as described above.
    Thirty minutes of pre-clearance observation are required prior to 
ramp-up for any shutdown of longer than 30 minutes (i.e., if the array 
were shut down during transit from one line to another). This 30 minute 
pre-clearance period may occur during any vessel activity (i.e., 
transit). If a marine mammal were observed within or approaching the 
100 m EZ during this pre-clearance period, ramp-up would not be 
initiated until all marine mammals cleared the EZ. Criteria for 
clearing the EZ would be as described above. If the airgun array has 
been shut down for reasons other than mitigation (e.g., mechanical 
difficulty) for a period of less than 30 minutes, it may be activated 
again without ramp-up if PSOs have maintained constant visual 
observation and no detections of any marine mammal have occurred within 
the EZ or buffer zone. Ramp-up would be planned to occur during periods 
of good visibility when possible. However, ramp-up would be allowed at 
night and during poor visibility if the 100 m EZ and 200 m buffer zone 
have been monitored by visual PSOs for 30 minutes prior to ramp-up.
    The operator would be required to notify a designated PSO of the 
planned start of ramp-up as agreed-upon with the lead PSO; the 
notification time should not be less than 60 minutes prior to the 
planned ramp-up. A designated PSO must be notified again immediately 
prior to initiating ramp-up procedures and the operator must receive 
confirmation from the PSO to proceed. The operator must provide 
information to PSOs documenting that appropriate procedures were 
followed. Following deactivation of the array for reasons other than 
mitigation, the operator would be required to communicate the near-term 
operational plan to the lead PSO with justification for any planned 
nighttime ramp-up.

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: Vessel operator 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 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 
knots or less when mother/calf pairs, pods, or large assemblages of 
cetaceans are observed near the vessel.
    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

[[Page 18689]]

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.
    SIO 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.
    SIO's monitoring and reporting plan includes the following 
measures:

Vessel-Based Visual Monitoring

    As described above, PSO observations would take place during 
daytime airgun operations and nighttime start-ups (if applicable) of 
the airguns. During seismic operations, three visual PSOs would be 
based aboard the Atlantis. PSOs would be appointed by SIO with NMFS 
approval. During the majority of seismic operations, one PSO would 
monitor for marine mammals around the seismic vessel. PSOs would be on 
duty in shifts of duration no longer than 4 hours. Other crew would 
also be instructed to assist in detecting marine mammals and in 
implementing mitigation requirements (if practical). During daytime, 
PSOs would scan the area around the vessel systematically with reticle 
binoculars (e.g., 7x50 Fujinon) 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 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

    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.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    To avoid repetition, our analysis applies to all the species listed 
in Table 2, given that NMFS expects the

[[Page 18690]]

anticipated effects of the proposed seismic survey to be similar in 
nature. Where there are meaningful differences between species or 
stocks, or groups of species, in anticipated individual responses to 
activities, impact of expected take on the population due to 
differences in population status, or impacts on habitat, NMFS has 
identified species-specific factors to inform the analysis.
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of SIO's proposed seismic survey, even in the absence 
of proposed mitigation. Thus the proposed authorization does not 
authorize any mortality. As discussed in the Potential Effects section, 
non-auditory physical effects, stranding, and vessel strike are not 
expected to occur.
    We propose to authorize a limited number of instances of Level A 
harassment (Table 11) for one species. However, we believe that any PTS 
incurred in marine mammals as a result of the proposed activity would 
be in the form of only a small degree of PTS and not total deafness 
that would not be likely to affect the fitness of any individuals, 
because of the constant movement of both the Atlantis and of the marine 
mammals in the project area, as well as the fact that the vessel is not 
expected to remain in any one area in which individual marine mammals 
would be expected to concentrate for an extended period of time (i.e., 
since the duration of exposure to loud sounds will be relatively 
short). Also, as described above, we expect that marine mammals would 
be likely to move away from a sound source that represents an aversive 
stimulus, especially at levels that would be expected to result in PTS, 
given sufficient notice of the Atlantis's approach due to the vessel's 
relatively low speed when conducting seismic surveys. We expect that 
the majority of takes would be in the form of short-term Level B 
behavioral harassment in the form of temporary avoidance of the area or 
decreased foraging (if such activity were occurring), reactions that 
are considered to be of low severity and with no lasting biological 
consequences (e.g., Southall et al., 2007).
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see Potential Effects of the Specified 
Activity on Marine Mammals and their Habitat). Marine mammal habitat 
may be impacted by elevated sound levels, but these impacts would be 
temporary. Feeding behavior is not likely to be significantly impacted, 
as marine mammals appear to be less likely to exhibit behavioral 
reactions or avoidance responses while engaged in feeding activities 
(Richardson et al., 1995). Prey species are mobile and are broadly 
distributed throughout the project area; therefore, marine mammals that 
may be temporarily displaced during survey activities are expected to 
be able to resume foraging once they have moved away from areas with 
disturbing levels of underwater noise. Because of the temporary nature 
of the disturbance, the availability of similar habitat and resources 
in the surrounding area, and the lack of important or unique marine 
mammal habitat, the impacts to marine mammals and the food sources that 
they utilize are not expected to cause significant or long-term 
consequences for individual marine mammals or their populations. In 
addition, there are no feeding, mating or calving areas known to be 
biologically important to marine mammals within the proposed project 
area.
    As described above, though marine mammals in the survey area would 
not be assigned to NMFS stocks, for purposes of the small numbers 
analysis we rely on stock numbers from the U.S. Atlantic SARs as the 
best available information on the abundance estimates for the species 
of marine mammals that could be taken. The activity is expected to 
impact a very small percentage of all marine mammal populations that 
would be affected by SIO's proposed survey (less than 34 percent each 
for all marine mammal stocks, when compared with stocks from the U.S. 
Atlantic as described above). Additionally, the acoustic ``footprint'' 
of the proposed survey would be very small relative to the ranges of 
all marine mammals that would potentially be affected. Sound levels 
would increase in the marine environment in a relatively small area 
surrounding the vessel compared to the range of the marine mammals 
within the proposed survey area. The seismic array would be active 24 
hours per day throughout the duration of the proposed survey. However, 
the very brief overall duration of the proposed survey (25 days) would 
further limit potential impacts that may occur as a result of the 
proposed activity.
    The proposed mitigation measures are expected to reduce the number 
and/or severity of takes by allowing for detection of marine mammals in 
the vicinity of the vessel by visual and acoustic observers, and by 
minimizing the severity of any potential exposures via shutdowns of the 
airgun array. Based on previous monitoring reports for substantially 
similar activities that have been previously authorized by NMFS, we 
expect that the proposed mitigation will be effective in preventing at 
least some extent of potential PTS in marine mammals that may otherwise 
occur in the absence of the proposed mitigation.
    Of the marine mammal species under our jurisdiction that are likely 
to occur in the project area, the following species are listed as 
endangered under the ESA: Fin, sei, blue, 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 11), relative to 
their population sizes (again, when compared to U.S. Atlantic stocks, 
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 SIO's seismic 
survey are not listed as threatened or endangered under the ESA. There 
is no designated critical habitat for any ESA-listed marine mammals 
within the project area; 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 SIO's 
proposed seismic survey would result in only short-term (temporary and 
short in duration) effects to individuals exposed, or some small degree 
of PTS to a very small number of individuals of four species. 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 mortality is anticipated or authorized;
     The anticipated impacts of the proposed activity on marine 
mammals would primarily be temporary behavioral changes due to 
avoidance of the area around the survey vessel. The relatively short 
duration of the proposed survey (25 days) would further limit the 
potential impacts of any temporary behavioral changes that would occur;
     The number of instances of PTS that may occur are expected 
to be very small in number (Table 11). Instances of PTS that are 
incurred in marine mammals would be of a low level, due

[[Page 18691]]

to constant movement of the vessel and of the marine mammals in the 
area, and the nature of the survey design (not concentrated in areas of 
high marine mammal concentration);
     The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the proposed survey to avoid exposure to sounds from the activity;
     The proposed project area does not contain areas of 
significance for feeding, mating or calving;
     The potential adverse effects on fish or invertebrate 
species that serve as prey species for marine mammals from the proposed 
survey would be temporary and spatially limited; 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.
    Marine mammals potentially taken by the proposed survey would not 
be expected to originate from the U.S. Atlantic stocks as defined by 
NMFS (Hayes et al., 2017). However, population abundance data for 
marine mammal species in the survey area is not available, therefore in 
most cases the U.S. Atlantic SARs represent the best available 
information on marine mammal abundance in the Northwest Atlantic Ocean. 
For certain species (i.e., fin whale, minke whale and common dolphin) 
the 2007 Canadian Trans-North Atlantic Sighting Survey (TNASS), which 
provided full coverage of the Atlantic Canadian coast (Lawson and 
Gosselin, 2009) represents the best available information on abundance. 
Abundance estimates from TNASS were corrected for perception and 
availability bias, when possible. In general, where the TNASS survey 
effort provided more extensive coverage of a stock's range (as compared 
with NOAA shipboard survey effort), we elected to use the resulting 
abundance estimate over the current NMFS abundance estimate (derived 
from survey effort with more limited coverage of the stock range). For 
the humpback whale, NMFS defines a stock of humpback whales in the 
Atlantic only on the basis of the Gulf of Maine feeding population; 
however, multiple feeding populations originate from the DPS of 
humpback whales that is expected to occur in the proposed survey area 
(the West Indies DPS). As West Indies DPS whales from multiple feeding 
populations may be encountered in the proposed survey area, the total 
abundance of the West Indies DPS best reflects the abundance of the 
population that may encountered by the proposed survey. The West Indies 
DPS abundance estimate used here reflects the latest estimate as 
described in the NMFS Status Review of the Humpback Whale under the 
Endangered Species Act (Bettridge et al., 2015). Therefore, we use 
abundance data from the SARs in most cases, as well as from the TNASS 
and NMFS Status Review, for purposes of the small numbers analysis. The 
numbers of takes that we propose for authorization to be taken, for all 
species and stocks are less than a third of the population abundance 
for all species and stocks, when compared to abundance estimates from 
U.S. Atlantic SARs and TNASS and NMFS Status Review (Table 11). We 
again note that while some animals from U.S. stocks may occur in the 
proposed survey area, the proposed survey area is outside the 
geographic boundaries of the U.S. Atlantic SARs, thus populations of 
marine mammals in the proposed survey area would not be limited to the 
U.S. stocks and those populations may in fact be larger than the U.S. 
stock abundance estimates. In addition, it should be noted that take 
numbers represent instances of take, not individuals taken. Given the 
relatively small survey grids (Figure 1 in the IHA application), it is 
reasonable to expect that some individuals may be exposed more than one 
time, which would mean that the number of individuals taken is somewhat 
smaller than the total instances of take indicated in Table 1.
    No known current regional population estimates are available for 5 
marine mammal species that could be incidentally taken as a result of 
the proposed survey: The Bryde's whale, killer whale, pygmy killer 
whale, Northern bottlenose whale, and ringed seal. NMFS has reviewed 
the geographic distributions of these species in determining whether 
the numbers of takes proposed for authorization herein are likely to 
represent small numbers. Bryde's whales are distributed worldwide in 
tropical and sub-tropical waters (Kato and Perrin, 2009). Killer whales 
are broadly distributed in the Atlantic from the Arctic ice edge to the 
West Indies (Waring et al., 2015). The pygmy killer whale is 
distributed worldwide in tropical to sub-tropical waters (Jefferson et 
al. 1994). 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 (Waring et 
al., 2015). The harp seal occurs throughout much of the North Atlantic 
and Arctic Oceans (Lavigne and Kovacs 1988). Based on the broad spatial 
distributions of these species relative to the areas where the proposed 
surveys would occur, NMFS preliminarily concludes that the authorized 
take of these species represent small numbers relative to the affected 
species' overall population sizes, though we are unable to quantify the 
proposed take numbers as a percentage of population.
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals will be taken relative to the population size 
of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
preliminarily determined that the total taking of affected species or 
stocks would not have an unmitigable adverse impact on the availability 
of such species or stocks for taking for subsistence purposes.

Endangered Species Act (ESA)

    Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.) 
requires that each Federal agency insure that any action it authorizes, 
funds, or carries out is not likely to jeopardize the continued

[[Page 18692]]

existence of any endangered or threatened species or result in the 
destruction or adverse modification of designated critical habitat. To 
ensure ESA compliance for the issuance of IHAs, NMFS consults 
internally, in this case with the ESA Interagency Cooperation Division, 
whenever we propose to authorize take for endangered or threatened 
species.
    The NMFS Permits and Conservation Division is proposing to 
authorize the incidental take of 4 species of marine mammals which are 
listed under the ESA: the sei whale, fin whale, blue whale and sperm 
whale. We have requested initiation of Section 7 consultation with the 
Interagency Cooperation Division for the issuance of this IHA. NMFS 
will conclude the ESA section 7 consultation prior to reaching a 
determination regarding the proposed issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to SIO for conducting a low-energy seismic survey in the 
Northwest Atlantic Ocean in June-July 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 SIO IHA application and using an airgun array 
aboard the R/V Atlantis 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 SIO, the vessel 
operator and other relevant personnel, the lead PSO, and any other 
relevant designees of SIO operating under the authority of this IHA.
    (b) The species authorized for taking are listed in Table 11. The 
taking, by Level A and Level B harassment only, is limited to the 
species and numbers listed in Table 11. Any taking exceeding the 
authorized amounts listed in Table 11 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 11 are detected by PSOs, the acoustic source 
must be shut down to avoid unauthorized take.
    (e) SIO shall ensure that the vessel operator and other relevant 
vessel personnel are briefed on all responsibilities, communication 
procedures, marine mammal monitoring protocol, operational procedures, 
and IHA requirements prior to the start of survey activity, and when 
relevant new personnel join the survey operations.
    4. Mitigation Requirements
    The holder of this Authorization is required to implement the 
following mitigation measures:
    (a) SIO 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 vessel operator.
    (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), typically two, and minimally one, 
PSO(s) must be on duty and conducting visual observations at all times 
during daylight hours (i.e., from 30 minutes prior to sunrise through 
30 minutes following sunset).
    (ii) Visual monitoring must begin not less than 30 minutes prior to 
ramp-up, including for nighttime ramp-ups of the airgun array, and must 
continue until one hour after use of the acoustic source ceases or 
until 30 minutes past sunset.
    (iii) PSOs shall coordinate to ensure 360[deg] visual coverage 
around the vessel from the most appropriate observation posts and shall 
conduct visual observations using binoculars and the naked eye while 
free from distractions and in a consistent, systematic, and diligent 
manner.
    (iv) PSOs may be on watch for a maximum of four consecutive hours 
followed by a break of at least one hour between watches and may 
conduct a maximum of 12 hours observation per 24 hour period.
    (v) During good conditions (e.g., daylight hours; Beaufort sea 
state 3 or less), visual PSOs shall conduct observations when the 
acoustic source is not operating for comparison of sighting rates and 
behavior with and without use of the acoustic source and between 
acquisition periods, to the maximum extent practicable.
    (d) Exclusion Zone and buffer zone--PSOs shall establish and 
monitor a 100 m EZ and 200 m buffer zone. The zones shall be based upon 
radial distance from any element of the airgun array (rather than being 
based on the center of the array or around the vessel itself). During 
use of the acoustic source, occurrence of marine mammals outside the EZ 
but within 200 m from any element of the airgun array shall be 
communicated to the operator to prepare for potential further 
mitigation measures as described below. During use of the acoustic 
source, occurrence of marine mammals within the EZ, or on a course to 
enter the EZ, shall trigger further mitigation measures as described 
below.
    (i) Ramp-up--A ramp-up procedure is required at all times as part 
of the activation of the acoustic source. Ramp-up would begin with one 
45 in\3\ airgun, and the second 45 in\3\ airgun would be added after 5 
minutes.
    (ii) If the airgun array has been shut down due to a marine mammal 
detection, ramp-up shall not occur until all marine mammals have 
cleared the EZ. A marine mammal is considered to have cleared the EZ 
if:
    (A) It has been visually observed to have left the EZ; or
    (B) It has not been observed within the EZ, for 15 minutes (in the 
case of small odontocetes) or for 30 minutes (in the case of mysticetes 
and large odontocetes including sperm, pygmy sperm, and beaked whales).
    (iii) Thirty minutes of pre-clearance observation of the 100 m EZ 
and 200 m buffer zone are required prior to ramp-up for any shutdown of 
longer than 30 minutes. This pre-clearance period may occur during any 
vessel activity. If any marine mammal (including delphinids) is 
observed within or approaching the EZ or 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 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 all other species).
    (iv) During ramp-up, at least two PSOs shall monitor the 100 m EZ 
and 200 m buffer zone. Ramp-up may not be initiated if any marine 
mammal (including delphinids) is observed within or approaching the 100 
m EZ. If

[[Page 18693]]

a marine mammal is observed within or approaching the 100 m EZ during 
ramp-up, a shutdown shall be implemented as though the full array were 
operational. Ramp-up may not begin again until the animal(s) has been 
observed exiting the 100 m EZ or until an additional time period has 
elapsed with no further sightings (i.e., 15 minutes for small 
odontocetes and 30 minutes for mysticetes and large odontocetes 
including sperm, pygmy sperm, and beaked whales).
    (v) If the airgun array has been shut down for reasons other than 
mitigation (e.g., mechanical difficulty) for a period of less than 30 
minutes, it may be activated again without ramp-up if PSOs have 
maintained constant visual observation and no visual detections of any 
marine mammal have occurred within the buffer zone.
    (vi) Ramp-up at night and at times of poor visibility shall only 
occur where operational planning cannot reasonably avoid such 
circumstances. Ramp-up may occur at night and during poor visibility if 
the 100 m EZ and 200 m buffer zone have been continually monitored by 
visual PSOs for 30 minutes prior to ramp-up with no marine mammal 
detections.
    (vii) The vessel operator must notify a designated PSO of the 
planned start of ramp-up. The designated PSO must be notified again 
immediately prior to initiating ramp-up procedures and the operator 
must receive confirmation from the PSO to proceed.
    (e) Shutdown requirements--An exclusion zone of 100 m shall be 
established and monitored by PSOs. If a marine mammal is observed 
within, entering, or approaching the 100 m exclusion zone all airguns 
shall be shut down.
    (i) Any PSO on duty has the authority to call for shutdown of the 
airgun array. When there is certainty regarding the need for mitigation 
action on the basis of visual detection, the relevant PSO(s) must call 
for such action immediately.
    (ii) The operator must establish and maintain clear lines of 
communication directly between PSOs on duty and crew controlling the 
airgun array to ensure that shutdown commands are conveyed swiftly 
while allowing PSOs to maintain watch.
    (iii) When a shutdown is called for by a PSO, the shutdown must 
occur and any dispute resolved only following shutdown.
    (iv) The shutdown requirement is waived for dolphins of the 
following genera: Tursiops, Steno, Stenella, Lagenorhynchus and 
Delphinus. The shutdown waiver only applies if animals are traveling, 
including approaching the vessel. If animals are stationary and the 
vessel approaches the animals, the shutdown requirement applies. If 
there is uncertainty regarding identification (i.e., whether the 
observed animal(s) belongs to the group described above) or whether the 
animals are traveling, shutdown must be implemented.
    (v) Upon implementation of a shutdown, the source may be 
reactivated under the conditions described at 4(e)(vi). Where there is 
no relevant zone (e.g., shutdown due to observation of a calf), a 30-
minute clearance period must be observed following the last observation 
of the animal(s).
    (vi) Shutdown of the array is required upon observation of a whale 
(i.e., sperm whale or any baleen whale) with calf, with ``calf'' 
defined as an animal less than two-thirds the body size of an adult 
observed to be in close association with an adult, at any distance.
    (vii) Shutdown of the array is required upon observation of an 
aggregation (i.e., six or more animals) of large whales of any species 
(i.e., sperm whale or any baleen whale) that does not appear to be 
traveling (e.g., feeding, socializing, etc.) at any distance.
    (f) Vessel Strike Avoidance--Vessel operator and crew must maintain 
a vigilant watch for all marine mammals and slow down or stop the 
vessel or alter course, as appropriate, to avoid striking any marine 
mammal. 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, pods, or large assemblages of cetaceans are observed 
near the vessel.
    (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 90 
in\3\ (not including redundant backup airguns) must not be exceeded 
during the survey, except where unavoidable for source testing and 
calibration purposes. All occasions where activated source volume 
exceeds notified operational capacity must be noticed to the PSO(s) on 
duty and fully documented. The lead PSO must be granted access to 
relevant instrumentation documenting acoustic source power and/or 
operational volume.
    (ii) Testing of the acoustic source involving all elements requires 
normal mitigation protocols (e.g., ramp-up). Testing limited to 
individual source elements or strings does not require ramp-up but does 
require pre-clearance.
    5. Monitoring Requirements
    The holder of this Authorization is required to conduct marine 
mammal monitoring during survey activity. Monitoring shall be conducted 
in accordance with the following requirements:
    (a) The operator must provide a night-vision device suited for the 
marine environment for use during nighttime ramp-up pre-clearance, at 
the discretion of the PSOs. At minimum, the device should feature 
automatic brightness and gain control, bright light protection, 
infrared illumination, and optics suited for low-light situations.
    (b) PSOs must also be equipped with reticle binoculars (e.g., 7x50) 
of appropriate quality (i.e., Fujinon or equivalent), 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

[[Page 18694]]

    (i) PSOs must have successfully completed relevant training, 
including completion of all required coursework and passing a written 
and/or oral examination developed for the training program.
    (ii) PSOs must have successfully attained a bachelor's degree from 
an accredited college or university with a major in one of the natural 
sciences and a minimum of 30 semester hours or equivalent in the 
biological sciences and at least one undergraduate course in math or 
statistics. The educational requirements may be waived if the PSO has 
acquired the relevant skills through alternate experience. Requests for 
such a waiver must include written justification. Alternate experience 
that may be considered includes, but is not limited to (1) secondary 
education and/or experience comparable to PSO duties; (2) previous work 
experience conducting academic, commercial, or government-sponsored 
marine mammal surveys; or (3) previous work experience as a PSO; the 
PSO should demonstrate good standing and consistently good performance 
of PSO duties.
    (d) Data Collection--PSOs must use standardized data forms, whether 
hard copy or electronic. PSOs shall record detailed information about 
any implementation of mitigation requirements, including the distance 
of animals to the acoustic source and description of specific actions 
that ensued, the behavior of the animal(s), any observed changes in 
behavior before and after implementation of mitigation, and if shutdown 
was implemented, the length of time before any subsequent ramp-up of 
the acoustic source to resume survey. If required mitigation was not 
implemented, PSOs should submit a description of the circumstances. We 
require that, at a minimum, the following information be reported:
    (i) PSO names and affiliations
    (ii) Dates of departures and returns to port with port name
    (iii) Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort
    (iv) Vessel location (latitude/longitude) when survey effort begins 
and ends; vessel location at beginning and end of visual PSO duty 
shifts
    (v) Vessel heading and speed at beginning and end of visual PSO 
duty shifts and upon any line change
    (vi) Environmental conditions while on visual survey (at beginning 
and end of PSO shift and whenever conditions change significantly), 
including wind speed and direction, Beaufort sea state, Beaufort wind 
force, swell height, weather conditions, cloud cover, sun glare, and 
overall visibility to the horizon
    (vii) Factors that may be contributing to impaired observations 
during each PSO shift change or as needed as environmental conditions 
change (e.g., vessel traffic, equipment malfunctions)
    (viii) Survey activity information, such as acoustic source power 
output while in operation, number and volume of airguns operating in 
the array, tow depth of the array, and any other notes of significance 
(i.e., pre-ramp-up survey, ramp-up, shutdown, testing, shooting, ramp-
up completion, end of operations, streamers, etc.)
    (ix) If a marine mammal is sighted, the following information 
should be recorded:
    (A) Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
    (B) PSO who sighted the animal;
    (C) Time of sighting;
    (D) Vessel location at time of sighting;
    (E) Water depth;
    (F) Direction of vessel's travel (compass direction);
    (G) Direction of animal's travel relative to the vessel;
    (H) Pace of the animal;
    (I) Estimated distance to the animal and its heading relative to 
vessel at initial sighting;
    (J) Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified); also note the composition 
of the group if there is a mix of species;
    (K) Estimated number of animals (high/low/best);
    (L) Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
    (M) Description (as many distinguishing features as possible of 
each individual seen, including length, shape, color, pattern, scars or 
markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
    (N) Detailed behavior observations (e.g., number of blows, number 
of surfaces, breaching, spyhopping, diving, feeding, traveling; as 
explicit and detailed as possible; note any observed changes in 
behavior);
    (O) Animal's closest point of approach and/or closest distance from 
the center point of the acoustic source;
    (P) Platform activity at time of sighting (e.g., deploying, 
recovering, testing, shooting, data acquisition, other); and
    (Q) Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up, speed or course alteration, 
etc.) and time and location of the action.
    6. Reporting
    (a) SIO shall submit a draft comprehensive report on all activities 
and monitoring results within 90 days of the completion of the survey 
or expiration of the IHA, whichever comes sooner. The report must 
describe all activities conducted and sightings of marine mammals near 
the activities, must provide full documentation of methods, results, 
and interpretation pertaining to all monitoring, and must summarize the 
dates and locations of survey operations and all marine mammal 
sightings (dates, times, locations, activities, associated survey 
activities). Geospatial data regarding locations where the acoustic 
source was used must be provided as an ESRI shapefile with all 
necessary files and appropriate metadata. In addition to the report, 
all raw observational data shall be made available to NMFS. The report 
must summarize the data collected as required under condition 5(d) of 
this IHA. The draft report must be accompanied by a certification from 
the lead PSO as to the accuracy of the report, and the lead PSO may 
submit directly to NMFS a statement concerning implementation and 
effectiveness of the required mitigation and monitoring. A final report 
must be submitted within 30 days following resolution of any comments 
from NMFS on the draft report.
    (b) Reporting injured or dead marine mammals:
    (i) In the event that the specified activity clearly causes the 
take of a marine mammal in a manner not prohibited by this IHA (if 
issued), such as serious injury or mortality, SIO shall immediately 
cease the specified activities and immediately report the incident to 
the NMFS Office of Protected Resources. The report must include the 
following information:
    (A) Time, date, and location (latitude/longitude) of the incident;
    (B) Vessel's speed during and leading up to the incident;
    (C) Description of the incident;
    (D) Status of all sound source use in the 24 hours preceding the 
incident;
    (E) Water depth;
    (F) Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, and visibility);
    (G) Description of all marine mammal observations in the 24 hours 
preceding the incident;
    (H) Species identification or description of the animal(s) 
involved;
    (I) Fate of the animal(s); and
    (J) Photographs or video footage of the animal(s).
    Activities shall not resume until NMFS is able to review the 
circumstances of the prohibited take.

[[Page 18695]]

NMFS will work with SIO to determine what measures are necessary to 
minimize the likelihood of further prohibited take and ensure MMPA 
compliance. SIO may not resume their activities until notified by NMFS.
    (ii) In the event that SIO discovers an injured or dead marine 
mammal, and the lead observer determines that the cause of the injury 
or death is unknown and the death is relatively recent (e.g., in less 
than a moderate state of decomposition), SIO shall immediately report 
the incident to 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 SIO to determine whether additional 
mitigation measures or modifications to the activities are appropriate.
    (iii) In the event that SIO discovers an injured or dead marine 
mammal, and the lead observer determines that the injury or death is 
not associated with or related to the specified activities (e.g., 
previously wounded animal, carcass with moderate to advanced 
decomposition, or scavenger damage), SIO shall report the incident to 
the NMFS Office of Protected Resources within 24 hours of the 
discovery. SIO shall provide photographs or video footage or other 
documentation of the sighting to NMFS.
    7. This Authorization may be modified, suspended or withdrawn if 
the holder fails to abide by the conditions prescribed herein, or if 
NMFS determines the authorized taking is having more than a negligible 
impact on the species or stock of affected marine mammals.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this Notice of Proposed IHA for the proposed 
survey. 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.
    On a case-by-case basis, NMFS may issue a second one-year IHA 
without additional notice when (1) another year of identical or nearly 
identical activities as described in the Specified Activities section 
is planned or (2) the activities would not be completed by the time the 
IHA expires and a second IHA would allow for completion of the 
activities beyond that described in the Dates and Duration section, 
provided all of the following conditions are met:
     A request for renewal is received no later than 60 days 
prior to expiration of the current IHA.
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted beyond the 
initial dates either are identical to the previously analyzed 
activities or include changes so minor (e.g., reduction in pile size) 
that the changes do not affect the previous analyses, take estimates, 
or mitigation and monitoring requirements.
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
     Upon review of the request for renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures remain the same and appropriate, 
and the original findings remain valid.

    Dated: April 24, 2018.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2018-08891 Filed 4-26-18; 8:45 am]
 BILLING CODE 3510-22-P