[Federal Register Volume 85, Number 117 (Wednesday, June 17, 2020)]
[Notices]
[Pages 36537-36562]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-12997]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XA159]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to Marine Site Characterization 
Surveys Off of Coastal Virginia

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

ACTION: Notice; proposed incidental harassment authorization; request 
for comments on proposed authorization and possible Renewal.

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SUMMARY: NMFS has received a request from Dominion Energy Virginia 
(Dominion) for authorization to take marine mammals incidental to 
marine site characterization surveys in the areas of the Commercial 
Lease of Submerged Lands for Renewable Energy Development on the Outer 
Continental Shelf (OCS) Offshore Virginia (Lease No. OCS-A-0483) as 
well as in coastal waters where an export cable corridor will be 
established in support of the Coastal Virginia Offshore Wind Commercial 
(CVOW Commercial) Project. Pursuant to the Marine Mammal Protection Act 
(MMPA), NMFS is requesting comments on its proposal to issue an 
incidental harassment authorization (IHA) to incidentally take marine 
mammals during the specified activities. NMFS is also requesting 
comments on a possible one-year renewal that could be issued under 
certain circumstances and if all requirements are met, as described in 
Request for Public Comments at the end of this notice. NMFS will 
consider public comments prior to making any final decision on the 
issuance of the requested MMPA authorizations and agency responses will 
be summarized in the final notice of our decision.

DATES: Comments and information must be received no later than July 17, 
2020.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Physical comments should be sent to 
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments 
should be sent to [email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or

[[Page 36538]]

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

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

SUPPLEMENTARY INFORMATION:

Background

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

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs 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.
    We will review all comments submitted in response to this notice 
prior to concluding our NEPA process or making a final decision on the 
IHA request.

Summary of Request

    On February 7, 2020, NMFS received a request from Dominion for an 
IHA to take marine mammals incidental to marine site characterization 
surveys in the areas of the Commercial Lease of Submerged Lands for 
Renewable Energy Development on the OCS Offshore Virginia (Lease No. 
OCS-A-0483) as well as in coastal waters where an export cable corridor 
will be established in support of the offshore wind project. Dominion's 
proposed marine site characterization surveys include HRG and 
geotechnical survey activities. These survey activities would include 
two survey vessels and occur within both the Lease Area and the export 
cable corridor. For the purpose of this IHA the Lease Area and export 
cable corridors are collectively referred to as the Survey Area. 
Geophysical and shallow geotechnical survey activities are anticipated 
to be supported by two vessels. Each vessel will transit an estimated 
121.54 km of survey lines per day. The application was deemed adequate 
and complete on May 12, 2020. Dominion's request is for take of a small 
number of 11 species by Level B harassment only. Neither Dominion nor 
NMFS expects serious injury or mortality to result from this activity 
and, therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

    Dominion proposes to conduct high-resolution geophysical (HRG) and 
geotechnical surveys in support of offshore wind development projects 
in the areas of Commercial Lease of Submerged Lands for Renewable 
Energy Development on the OCS offshore Virginia (#OCS-A 0483) and along 
potential submarine cable routes to landfall locations in Virginia.
    The purpose of the marine site characterization surveys is to 
support the site characterization, facilities siting, and engineering 
design of offshore Project facilities including wind turbine 
generators, offshore substation(s), and submarine cables within the 
Lease Area and proposed export cable corridor. Underwater sound 
generated by Dominion's HRG equipment has the potential to result in 
incidental take of marine mammals in the form of behavioral harassment.

Dates and Duration

    HRG survey activities are anticipated to last approximately 161 
days and are anticipated to commence as soon as possible. Of those 
days, surveys will be conducted for 149 days in the Lease Area and 12 
days in the export cable corridor. This schedule is based on 24-hour 
operations and includes potential down time due to inclement weather. 
The survey days are based on total survey line kilometers (km) and 
represent a combined operational effort of two vessels operating 
concurrently. The actual allocation of survey effort between the two 
vessels will be dependent on weather, unforeseen down time, and other 
operational factors. These vessels will operate at least several 
kilometers apart, often operating with even greater distances of 
separation between the two vessels.

Specific Geographic Region

    Dominion will conduct surveys within the marine environment of the 
approximately 122,799-acre Lease Area and along the export cable 
corridor between the Lease Area and the Virginia shoreline (see Figure 
1). Water depths in the Lease Area range from about 22 meters (m) (72 
feet [ft]) to 38 m (125 ft). The export cable corridor begins at the 
western side of the Lease Area and extends southwest toward the coast 
of

[[Page 36539]]

Virginia for approximately 50 kilometers (km) (27 nautical miles [nm]). 
The export cable corridor will range from 600 m (1,968 ft) to 900 m 
(2,953 ft) wide and terminate at a proposed cable landing location 
along the Virginia Beach coastline. The exact landing location (between 
Croatan Beach and Sandbridge) is yet to be determined.
    For the purpose of this application, the Survey Area is defined as 
the Lease Area plus a 200-m buffer and export cable corridor that will 
be established in advance of conducting the survey activity. The Survey 
Area will include two distinct survey segments. The first survey 
segment will include full coverage HRG surveys conducted in a tartan-
pattern survey grid within the Lease Area; for this survey, a 200-m 
buffer was also included for line turns, run in and out, etc. Then, a 
full coverage HRG survey of the export cable corridor will cover up to 
a 900-m-wide corridor.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN17JN20.000

BILLING CODE 3510-22-C

Detailed Description of Specific Activity

    The proposed HRG and geotechnical survey activities are described 
below.

Geophysical Survey Activities

    Dominion has proposed that HRG survey operations would be conducted 
continuously 24 hours per day. The HRG survey activities proposed by 
Dominion would will include the following:
     Subsea positioning to calculate position by measuring the 
range and bearing from a vessel-mounted transceiver to an acoustic 
transponder;
     Depth sounding (multibeam depth sounder) to determine 
water depths and general bottom topography (currently estimated to 
range from approximately minimum vessel draft to 38 m [125 ft] in 
depth);
     Seafloor imaging (sidescan sonar survey) for seabed 
sediment classification purposes, to identify natural and man-made 
acoustic targets resting on the bottom as well as any anomalous 
features; and
     Medium penetration sub-bottom profiler (chirps/parametric 
profilers/sparkers) to map deeper subsurface stratigraphy as needed 
(soils down to 75 m [246 ft] to 100 m [328 ft] below seabed).
    Table 1 identifies the representative survey equipment that may be 
used in support of proposed geophysical survey activities that operate 
below 180 kilohertz (kHz) and produce signals that marine mammals may 
hear. HRG surveys are expected to use several equipment types 
concurrently in order to collect multiple aspects of geophysical data 
along one transect. Selection of equipment combinations is based on 
specific survey objectives.

[[Page 36540]]



                                      Table 1--Summary of Geophysical Survey Equipment Proposed for Use by Dominion
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                                      Representative HRG    Operating frequencies     RMS source      Peak source    Primary beam width   Pulse duration
            HRG system                    equipment                 (kHz)              level \1\       level \1\          (degrees)        (millisecond)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subsea Positioning/USBL...........  Sonardyne Ranger 2     35-55..................             188             191  90..................               1
                                     USBL.
                                    EvoLogics S2CR.......  48-78..................             178             186  Omnidirectional.....         500-600
                                    ixBlue Gaps..........  20-30..................             191             194  200.................            9-11
Multibeam Echosounder.............  R2Sonics 2026........  170-450................             191             221  0.45 x 0.45-1 x 1...     0.015-1.115
Synthetic Aperture Sonar (SAS),     Kraken Aquapix.......  337....................             210             213  >135 vertical, 1                1-10
 combined bathymetry/Sidescan \2\.                                                                                   horizontal.
Side Scan Sonar \2\...............  Edgetech 4200 dual     300 and 600............         \3\ 206         \3\ 212  140.................            5-10
                                     frequency.
Parametric SBP....................  Innomar SES-2000       2-22...................         \4\ 241             247  2...................          0.07-1
                                     medium 100.
Non-Parametric SBP................  Edgetech 216 Chirp...  2-16...................             193             196  15-25...............            5-40
                                    Edgetech 512 Chirp...  0.5-12.................             177         \5\ 191  16-41...............              20
Medium Penetration Seismic........  GeoMarine Dual 400     0.25-4.................             200         \6\ 210  Omnidirectional.....         0.5-0.8
                                     Sparker 800J.
                                    Applied Acoustics S-   0.5-3.5................         \7\ 203         \7\ 213  \8\ 60..............              10
                                     Boom (Triple Plate
                                     Boomer 1000J).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Source levels reported by manufacturer unless otherwise noted.
\2\ Operating frequencies are above all relevant marine mammal hearing thresholds, so are not assessed in this IHA.
\3\ The source levels are based on data from Crocker and Fratantonio (2016) for the EdgeTech 4200 for 100 percent power and 100 kHz.
\4\ The equipment specification sheets indicates a peak source level of 247 dB re 1 [mu]PA m. The average difference between the peak and SPLRMS source
  levels for sub-bottom profilers measured by Crocker and Fratantonio (2016) was 6 dB. Therefore, the estimated SPLRMS sound level is 241 dB re 1 [mu]PA
  m.
\5\ The source level are based on data from Crocker and Fratantonio (2016) for the EdgeTech 512i for 100 percent power.
\6\ The source levels were provided by the manufacturer within the document titled ``Noise Level Stacked 400--tuned''.
\7\ The source levels are based on data from Crocker and Fratantonio (2016) for the Applied Acoustics S-Boom with CSP-N Energy Source set at 1000
  Joules.
\8\ The beam width was based on data from Crocker and Fratantonio (2016) for the Applied Acoustics S-Boom. dB re 1 [mu]Pa m--decibels referenced to 1
  microPascal at 1 meter.

    The deployment of HRG survey equipment, including the equipment 
anticipated for use during Dominion's proposed activity, produces sound 
in the marine environment that has the potential to result in 
harassment of marine mammals. However, sound propagation in water is 
dependent on several factors including operating mode, frequency and 
beam direction of the HRG equipment; thus, potential impacts to marine 
mammals from HRG equipment are driven by the specification of 
individual HRG sources. The specifications of the potential equipment 
proposed for use during HRG survey activities (Table 1) were analyzed 
to determine which types of equipment would have the potential to 
result in harassment of marine mammals.

Geotechnical Equipment Use

    Geotechnical survey activities will include the following:
     Sample boreholes to determine geological and geotechnical 
characteristics of sediments;
     Deep cone penetration tests (CPTs) to determine 
stratigraphy and in situ conditions of the deep surface sediments; and
     Shallow CPTs to determine stratigraphy and in situ 
conditions of the near surface sediments.
    Geotechnical investigation activities are anticipated to be 
conducted from a drill ship equipped with dynamic positioning (DP) 
thrusters. Sound produced through use of DP thrusters is similar to 
that produced by transiting vessels and DP thrusters are typically 
operated either in a similarly predictable manner or used for short 
durations around stationary activities. NMFS does not believe acoustic 
impacts from DP thrusters are likely to result in take of marine 
mammals in the absence of activity- or location-specific circumstances 
that may otherwise represent specific concerns for marine mammals 
(i.e., activities proposed in area known to be of particular importance 
for a particular species), or associated activities that may increase 
the potential to result in take when in concert with DP thrusters. In 
this case, we are not aware of any such circumstances. Therefore, NMFS 
believes the likelihood of DP thrusters used during the proposed 
geotechnical surveys resulting in harassment of marine mammals to be so 
low as to be discountable. As DP thrusters are not expected to result 
in take of marine mammals, these activities are not analyzed further in 
this document.
    Field studies conducted off the coast of Virginia to determine the 
underwater noise produced by CPTs and borehole drilling found that 
these activities did not result in underwater noise levels that 
exceeded current thresholds for Level B harassment of marine mammals 
(Kalapinski 2015). Given the small size and energy footprint of CPTs 
and boring cores, NMFS believes the likelihood that noise from these 
activities would exceed the Level B harassment threshold at any 
appreciable distance is so low as to be discountable. Therefore, 
geotechnical survey activities, including CPTs and borehole drilling, 
are not expected to result in harassment of marine mammals and are not 
analyzed further in this document.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior

[[Page 36541]]

and life history, of the potentially affected species. Additional 
information regarding population trends and threats may be found in 
NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and 
more general information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS's website (https://www.fisheries.noaa.gov/find-species).
    Table 2 lists all species or stocks for which take is expected and 
proposed to be authorized for this action, and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and ESA and potential biological removal (PBR), where known. 
For taxonomy, we follow Committee on Taxonomy (2019). PBR is defined by 
the MMPA as the maximum number of animals, not including natural 
mortalities, that may be removed from a marine mammal stock while 
allowing that stock to reach or maintain its optimum sustainable 
population (as described in NMFS's SARs). While no mortality is 
anticipated or authorized here, PBR and annual serious injury and 
mortality from anthropogenic sources are included here as gross 
indicators of the status of the species and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS's stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS's U.S. Atlantic SARs (Hayes et al. 2019). All values presented in 
Table 2 are the most recent available at the time of publication and 
are available in the draft 2019 Atlantic and Gulf of Mexico Marine 
Mammal Stock Assessments available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/draft-marine-mammal-stock-assessment-reports.

                     Table 2--Marine Mammals Known To Occur in the Survey Area That May Be Affected by Dominion's Proposed Activity
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                                                                                         Stock abundance
                                                                      ESA/MMPA status;   (CV, Nmin, most     Predicted
          Common name            Scientific name         Stock         Strategic (Y/N)  recent abundance  abundance (CV)        PBR         Annual M/SI
                                                                             \1\           survey) \2\          \3\                             \4\
 
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
    North Atlantic Right whale  Eubalaena          Western North      E/D; Y..........  428 (0; 418; n/     * 535 (0.45)             0.8            5.55
                                 glacialis.         Atlantic (WNA).                      a).
Family Balaenopteridae
 (rorquals):
    Humpback whale............  Megaptera          Gulf of Maine....  -/-; N..........  1396 (0; 1380; n/ * 1,637 (0.07)              22            12.5
                                 novaeangliae.                                           a).
    Fin whale.................  Balaenoptera       WNA..............  E/D; Y..........  7,418 (0.25;        4,633 (0.08)              12            2.35
                                 physalus.                                               6,025; n/a).
    Sei whale.................  Balaenoptera       Nova Scotia......  E/D; Y..........  6,292 (1.015;       * 717 (0.30)             6.2               1
                                 borealis.                                               3,098; n/a).
    Minke whale...............  Balaenoptera       Canadian East      -/-; N..........  24,202 (0.3;      * 2,112 (0.05)           1,189               8
                                 acutorostrata.     Coast.                               18,902; n/a).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale...............  Physeter           NA...............  E, D,Y..........  4,349 (0.28,        5,353 (0.12)             6.9               0
                                 macrocephalus.                                          3,451; n/a).
Family Delphinidae:
    Short-finned pilot whale..  Globicephala       WNA..............  -/-; Y..........  28,924 (0.24;         \5\ 18,977             236             160
                                 macrorhynchus.                                          23,637; 2011).           (0.11)
    Long-finned pilot whale...  Globicephala       WNA..............  -/-; Y..........  39,215 (0.3;                                 306              21
                                 melas.                                                  30,627; n/a).
    Bottlenose dolphin........  Tursiops           WNA Offshore.....  -/-; N..........  62,851 (0.23;         \5\ 97,476             519              28
                                 truncatus.                                              15,914; 2011).           (0.06)
                                                   WNA Southern       -/-; Y..........  3,751 (0.06;                                  23          0-14.3
                                                    Migratory                            2,353; n/a).
                                                    Coastal.
    Common dolphin............  Delphinus delphis  WNA..............  -/-; N..........  172,825 (0.21;     86,098 (0.12)           1,452             419
                                                                                         145,216;2011).
    Atlantic white-sided        Lagenorhynchus     WNA..............  -/-; N..........  92,233 (0.71;      37,180 (0.07)             544              26
     dolphin.                    acutus.                                                 54,443; n/a).
    Atlantic spotted dolphin..  Stenella           WNA..............  -/-: N..........  39,921 (0.27;      55,436 (0.32)             303            54.3
                                 frontalis.                                              32,032; 2012).
    Risso's dolphin...........  Grampus griseus..  WNA..............  -/-; N..........  35,493 (0.19;       7,732 (0.09)             126            49.7
                                                                                         30,289; 2011).
Family Phocoenidae
 (porpoises):
Harbor porpoise...............  Phocoena phocoena  Gulf of Maine/Bay  -/-; N..........  95,543 (0.31;      45,089 (0.12)             851            2175
                                                    of Fundy.                            74,034; 2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae:
Harbor seal...................  Phoca vitulina...  WNA..............  -/-; N..........  75,834 (0.15,     ..............           2,006             350
                                                                                         66,884; 2012).

[[Page 36542]]

 
Gray seal \6\.................  Halichoerus        WNA..............  -/-; N..........  27,131 (0.19,     ..............           1,389           5,410
                                 grypus.                                                 23,158, n/a).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region/. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. In some cases, CV is not applicable.
\3\ This information represents species- or guild-specific abundance predicted by recent habitat-based cetacean density models (Roberts et al. 2016,
  2017, 2018). These models provide the best available scientific information regarding predicted density patterns of cetaceans in the U.S. Atlantic
  Ocean, and we provide the corresponding abundance predictions as a point of reference. Total abundance estimates were produced by computing the mean
  density of all pixels in the modeled area and multiplying by its area. For those species marked with an asterisk, the available information supported
  development of either two or four seasonal models; each model has an associated abundance prediction. Here, we report the maximum predicted abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range.
\5\ Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly,
  the habitat-based cetacean density models produced by Roberts et al. (2016, 2017, 2018) are based in part on available observational data which, in
  some cases, is limited to genus or guild in terms of taxonomic definition. Roberts et al. (2016, 2017, 2018) produced density models to genus level
  for Globicephala spp. and produced a density model for bottlenose dolphins that does not differentiate between offshore and coastal stocks.
\6\ NMFS stock abundance estimate applies to U.S. population only, actual stock abundance including Canada is approximately 505,000. The referenced PBR
  value applies only to the U.S. population and is therefore an underestimate for the stock as a whole.

    As indicated above, all 16 species (with 17 managed stocks) in 
Table 2 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur in the absence of 
mitigation measures.

North Atlantic Right Whale

    The North Atlantic right whale (Eubalaena glacialis) is considered 
one of the most critically endangered populations of large whales in 
the world and is listed as federally endangered under the ESA. The 
North Atlantic right whale ranges from calving grounds in the 
southeastern United States to feeding grounds in New England waters and 
into Canadian waters (Hayes et al. 2019). In the late fall months 
(e.g., October), right whales are generally thought to depart from the 
feeding grounds in the North Atlantic and move south to their calving 
grounds off Georgia and Florida. North Atlantic right whales may be 
found in feeding grounds within New England waters between February and 
May, with peak abundance in late March (Hayes et al. 2019). The 
offshore waters of Virginia, including waters of the Survey Area, are 
used as a migration corridor for right whales. Right whales occur 
during seasonal movements north or south between important feeding and 
breeding grounds (Knowlton et al. 2002; Firestone et al. 2008). Right 
whales are known to have extensive movements both within and between 
their winter and summer habitats, and their calving grounds are thought 
to extend as far north as Cape Fear, North Carolina (Hayes et al. 
2019). Right whales have been observed in coastal Atlantic waters year-
round seasons. They have been acoustically detected off Georgia and 
North Carolina in 7 of 11 months monitored (Hodge et al. 2015). Other 
recent passive acoustic studies of right whales off the Virginia coast 
demonstrate their year-round presence in Virginia (Salisbury et al. 
2016), with increased detections in fall and late winter/early spring. 
They are typically most common in the spring (late March) when they are 
migrating north and in the fall (i.e., October and November) during 
their southbound migration (Kenney and Vigness-Raposa 2010). There were 
sightings of up to eight right whales on two separate days in coastal 
Virginia in April of 2018 (April 9 and 11, 2018; Cotter 2019).
    However, recent research indicates our understanding of their 
movement patterns remains incomplete (Davis et al. 2017). A review of 
passive acoustic monitoring data from 2004 to 2014 throughout the 
western North Atlantic demonstrated nearly continuous year-round right 
whale presence across their entire habitat range (for at least some 
individuals), including in locations previously thought of as migratory 
corridors, suggesting that not all of the population undergoes a 
consistent annual migration (Davis et al. 2017). Movements within and 
between habitats are extensive, and the area offshore from the Mid-
Atlantic states is an important migratory corridor (Waring et al. 
2016). The Survey Area is not a known feeding area for right whales and 
right whales are not expected to be foraging there. Therefore, any 
right whales in the vicinity of the Survey Area are expected to be 
transient, most likely migrating through the area.
    Elevated North Atlantic right whale mortalities have occurred since 
June 7, 2017 along the U.S. and Canadian coast. A total of 30 confirmed 
dead stranded whales (21 in Canada; 9 in the United States) have been 
documented. This event has been declared an Unusual Mortality Event 
(UME), with human interactions, including entanglement in fixed fishing 
gear and vessel strikes, implicated in at least 13 of the mortalities 
thus far. More information is available online at: https://www.fisheries.noaa.gov/national/marine-life-distress/2017-2020-north-atlantic-right-whale-unusual-mortality-event.
    The proposed Survey Area is part of a migratory Biologically 
Important Area (BIA) for North Atlantic right whales; this important 
migratory area is comprised of the waters of the continental shelf 
offshore the East Coast of the United States and extends from Florida 
through Massachusetts. NMFS' regulations at 50 CFR part 224.105 
designated nearshore waters of the Mid-Atlantic Bight as Mid-Atlantic 
U.S. Seasonal Management Areas (SMA) for right whales in 2008. SMAs 
were developed to reduce the threat of collisions between ships and 
right whales around their migratory route and calving grounds. Portions 
of the Survey Area are located within the right whale mid-Atlantic SMA 
near Norfolk and the mouth of the Chesapeake Bay. The SMA is in effect 
from November 1 through April 30.

Humpback Whale

    Humpback whales are found worldwide in all oceans. Humpback whales 
were listed as endangered under

[[Page 36543]]

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.
    While migrating, humpback whales utilize the mid-Atlantic as a 
pathway between calving/mating grounds in the south to their feeding 
grounds in the north (Hayes et al. 2019). Not all humpback whales 
migrate to the Caribbean during winter, and some individuals of this 
species are sighted in mid- to high-latitude areas during winter 
(Swingle et al. 1993). The mid-Atlantic area may also serve as 
important habitat for juvenile humpback whales, as evidenced by 
increased levels of juvenile strandings along the Virginia and North 
Carolina coasts (Wiley et al. 1995). Similarly, Barco et al. (2002) 
suggested that the mid-Atlantic region primarily represents a 
supplemental winter feeding ground used by humpbacks.
    Since January 2016, elevated humpback whale mortalities have 
occurred along the Atlantic coast from Maine to Florida. This resulted 
in the declaration of a UME for this species. Partial or full necropsy 
examinations have been conducted on approximately half of the 123 known 
cases. Of the whales examined, about 50 percent had evidence of human 
interaction, either ship strike or entanglement. While a portion of the 
whales have shown evidence of pre-mortem vessel strike, this finding is 
not consistent across all whales examined and more research is needed. 
NOAA is consulting with researchers that are conducting studies on the 
humpback whale populations, and these efforts may provide information 
on changes in whale distribution and habitat use that could provide 
additional insight into how these vessel interactions occurred. Three 
previous UMEs involving humpback whales have occurred since 2000, in 
2003, 2005, and 2006. More information is available at: 
www.fisheries.noaa.gov/national/marine-life-distress/2016-2020-humpback-whale-unusual-mortality-event-along-atlantic-coast.

Fin Whale

    Fin whales are common in waters of the U.S. Atlantic Exclusive 
Economic Zone (EEZ), principally from Cape Hatteras northward (Waring 
et al. 2016). Fin whales are present in the Mid-Atlantic region during 
all four seasons, although sighting data indicate that they are more 
prevalent during winter, spring, and summer (Hayes et al. 2019). While 
fall is the season of lowest overall abundance off Virginia, they do 
not depart the area entirely. Fin whales, much like humpback whales, 
seem to exhibit habitat fidelity to feeding areas (Kenney and Vigness-
Raposa 2010; Hayes et al. 2019). While fin whales typically feed in the 
Gulf of Maine and the waters surrounding New England, mating and 
calving (and general wintering) areas are largely unknown (Hayes et al. 
2019).

Sei Whale

    The Nova Scotia stock of sei whales can be found in deeper waters 
of the continental shelf edge waters of the eastern United States and 
northeastward to south of Newfoundland. The southern portion of the 
stock's range during spring and summer includes the Gulf of Maine and 
Georges Bank. Spring is the period of greatest abundance in U.S. 
waters, with sightings concentrated along the eastern margin of Georges 
Bank and into the Northeast Channel area, and along the southwestern 
edge of Georges Bank in the area of Hydrographer Canyon (Waring et al. 
2015). In the waters off of Virginia, sei whales are uncommon; however, 
a 2018 aerial survey conducted by the U.S. Navy recorded sei whales in 
the area surrounding Norfolk Canyon (U.S. Navy n.d.).

Minke Whale

    Minke whales can be found in temperate, tropical, and high-latitude 
waters. The Canadian East Coast stock can be found in the area from the 
western half of the Davis Strait (45[deg] W) to the Gulf of Mexico 
(Waring et al. 2016). This species generally occupies waters less than 
100 m deep on the continental shelf. Little is known about minke 
whales' specific movements through the mid-Atlantic region; however, 
there appears to be a strong seasonal component to minke whale 
distribution, with acoustic detections indicating that they migrate 
south in mid-October to early November, and return from wintering 
grounds starting in March through early April (Risch et al. 2014). 
Northward migration appears to track the warmer waters of the Gulf 
Stream along the continental shelf, while southward migration is made 
farther offshore (Risch et al. 2014).
    Since January 2017, elevated minke whale mortalities have occurred 
along the Atlantic coast from Maine through South Carolina, with a 
total of 83 strandings at the time of publication of this notice. There 
have been eight recorded strandings in Virginia and two in North 
Carolina. This event has been declared a UME. Full or partial necropsy 
examinations were conducted on more than 60 percent of the whales. 
Preliminary findings in several of the whales have shown evidence of 
human interactions or infectious disease, but these findings are not 
consistent across all of the whales examined, so more research is 
needed. More information is available at: www.fisheries.noaa.gov/national/marine-life-distress/2017-2020-minke-whale-unusual-mortality-event-along-atlantic-coast.

Sperm Whale

    The distribution of the sperm whale in the U.S. EEZ occurs on the 
continental shelf edge, over the continental slope, and into mid-ocean 
regions (Waring et al. 2019). The basic social unit of the sperm whale 
appears to be the mixed school of adult females plus their calves and 
some juveniles of both sexes, normally numbering 20-40 animals in all. 
There is evidence that some social bonds persist for many years 
(Christal et al. 1998). This species forms stable social groups, site 
fidelity, and latitudinal range limitations in groups of females and 
juveniles (Whitehead, 2002). In winter, sperm whales concentrate east 
and northeast of Cape Hatteras. In spring, distribution shifts 
northward to east of Delaware and Virginia, and is widespread 
throughout the central Mid-Atlantic Bight and the southern part of 
Georges Bank. In the fall, sperm whale occurrence on the continental 
shelf south of New England reaches peak levels, and there remains a 
continental shelf edge occurrence in the Mid-Atlantic Bight (Waring et 
al. 2015). Off the coast of Virginia, sperm whales have recently been 
observed spending a significant amount of time near Norfolk Canyon and 
in waters over 1,800 m deep (6,000 ft; U.S. Navy n.d. 2017).

Pilot Whale

    The two species of pilot whales in the Western Atlantic include the 
long-finned and short-finned pilot whale. Both species of pilot whale 
are more generally found along the edge of the continental shelf at 
depths of 100 to 1,000 m (330 to 3,300 ft), choosing areas of high 
relief or submerged banks. Long-finned pilot whales, in the western

[[Page 36544]]

North Atlantic, are more pelagic occurring in especially high densities 
in winter and early spring over the continental slope, then moving 
inshore and onto the shelf in summer and autumn following squid and 
mackerel populations (Reeves et al. 2002). They frequently travel into 
the central and northern Georges Bank, Great South Channel, and 
northward into the Gulf of Maine areas during the late spring through 
late fall (Hayes et al. 2019). Short-finned pilot whales prefer 
tropical, subtropical, and warm temperate waters (Jefferson et al. 
2015). The short-finned pilot whale mostly ranges from New Jersey south 
through Florida, the northern Gulf of Mexico, and the Caribbean without 
any seasonal movements or concentrations (Hayes et al. 2019). 
Populations for both of these species overlap spatially along the mid- 
Atlantic shelf break between New Jersey and the southern flank of 
Georges Bank (Hayes et al. 2019). The latitudinal ranges of the two 
species remain uncertain, although south of Cape Hatteras, most pilot 
whale sightings are expected to be short-finned pilot whales, while 
north of ~42[deg] N most pilot whale sightings are expected to be long-
finned pilot whales (Hayes et al. 2019).

Bottlenose Dolphin

    The population of bottlenose dolphins in the North Atlantic 
consists of a complex mosaic of dolphin stocks (Waring et al. 2016). 
There are two stocks that may be found in the vicinity of the Survey 
Area--the western North Atlantic Offshore Stock (WNAOS) and the 
Southern Coastal Migratory Stock (SCMS). There are two distinct 
bottlenose dolphin morphotypes: migratory coastal and offshore. The 
migratory coastal morphotype resides in waters typically less than 20 m 
(65.6 ft) deep, along the inner continental shelf (within 7.5 km [4.6 
miles] of shore; Hayes et al. 2018). This migratory coastal population 
was further subdivided into seven stocks based largely upon spatial 
distribution (Waring et al. 2016). The SCMS is the coastal stock found 
south of Assateague, Virginia, to northern Florida and is the stock 
most likely to be encountered in the vicinity of the export cable 
portion of the Survey Area. Seasonally, SCMS movements indicate they 
are mostly found in southern North Carolina (Cape Lookout) from October 
to December; they continue to move farther south from January to March 
to as far south as northern Florida and move back north to coastal 
North Carolina from April to June. SCMS bottlenose dolphins occupy 
waters north of Cape Lookout, North Carolina, to as far north as 
Chesapeake Bay from July to August. An observed shift in spatial 
distribution during a summer 2004 survey indicated that the northern 
boundary for the SCMS may vary from year to year (Hayes et al. 2018). 
The offshore population consists of one stock (WNAOS) in the western 
North Atlantic Ocean distributed primarily along the outer continental 
shelf and continental slope, and distributed widely during the spring 
and summer from Georges Bank to the Florida Keys with late summer and 
fall incursions as far north the Gulf of Maine depending on water 
temperatures (Kenney 1990; Hayes et al. 2017). The WNAOS is found 
seaward of 34 km (21 miles) and in deeper waters).
    A combined genetic and logistic regression analysis that 
incorporated depth, latitude, and distance from shore was used to model 
the probability that a particular common bottlenose dolphin group seen 
in coastal waters was of the coastal versus offshore morphotype 
(Garrison et al. 2017a). North of Cape Hatteras during summer months, 
there is strong separation between the coastal and offshore morphotypes 
(Kenney 1990; Garrison et al. 2017a), and the coastal morphotype is 
nearly completely absent in waters >20 m depth. South of Cape Hatteras, 
the regression analysis indicated that the coastal morphotype is most 
common in waters <20 m deep, but occurs at lower densities over the 
continental shelf, in waters >20 m deep, where it overlaps to some 
degree with the offshore morphotype. For the purposes of defining stock 
boundaries, estimating abundance, and identifying bycaught samples, the 
offshore boundary of the SMCS is defined as the 20-m isobath north of 
Cape Hatteras and the 200-m isobath south of Cape Hatteras. In summary, 
this stock is best delimited in warm water months, when it overlaps 
least with other stocks, as common bottlenose dolphins of the coastal 
morphotype that occupy coastal waters from the shoreline to 200 m depth 
from Cape Lookout to Cape Hatteras, North Carolina, and coastal waters 
0-20 m in depth from Cape Hatteras to Assateague, Virginia, including 
Chesapeake Bay (Hayes et al. 2018).

Common Dolphin

    The common dolphin is found world-wide in temperate to subtropical 
seas. In the North Atlantic, common dolphins are commonly found over 
the continental shelf between the 200-m and 2,000-m isobaths and over 
prominent underwater topography and east to the mid-Atlantic Ridge. 
Common dolphins have been noted to be associated with Gulf Stream 
features (CETAP 1982; Selzer and Payne 1988; Waring et al. 1992). The 
species is seasonally found in abundance between Cape Hatteras and 
Georges Bank from mid-January to May. Between mid-summer and fall they 
migrate onto Georges Bank and the Scotian Shelf, and large aggregations 
occur on Georges Bank in fall (Reeves et al. 2002; Hayes et al. 2019). 
The species is less common south of Cape Hatteras, although schools 
have been reported as far south as the Georgia/South Carolina border 
(Hayes et al. 2019).

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 from central West Greenland to North Carolina (Waring et 
al. 2017). The Gulf of Maine stock is most common in continental shelf 
waters from Hudson Canyon to Georges Bank, and in the Gulf of Maine and 
lower Bay of Fundy. Sighting data indicate seasonal shifts in 
distribution (Northridge et al. 1997). During January to May, low 
numbers of white-sided dolphins are found from Georges Bank to Jeffreys 
Ledge (off New Hampshire), with even lower numbers south of Georges 
Bank, as documented by a few strandings collected on beaches of 
Virginia to South Carolina. From June through September, large numbers 
of white-sided dolphins are found from Georges Bank to the lower Bay of 
Fundy. From October to December, white-sided dolphins occur at 
intermediate densities from southern Georges Bank to southern Gulf of 
Maine. Infrequent Virginia and North Carolina observations appear to 
represent the southern extent of the species' range during the winter 
months (Hayes et al. 2019).

Atlantic Spotted Dolphin

    Atlantic spotted dolphins are found in tropical and warm temperate 
waters along the continental shelf from 10 to 200 m (33 to 650 ft) deep 
to slope waters greater than 500 m (1,640 ft). Their range extends from 
southern New England, south to Gulf of Mexico and the Caribbean to 
Venezuela (Waring et al. 2014). This stock regularly occurs in 
continental shelf waters south of Cape Hatteras and in continental 
shelf edge and continental slope waters north of this region (Waring et 
al. 2014). There are two forms of this species, with the larger ecotype 
inhabiting the continental shelf and is usually found inside or near 
the 200-m isobaths (Waring et al. 2014).

[[Page 36545]]

Risso's Dolphin

    Risso's dolphins are distributed worldwide in tropical and 
temperate seas and in the Northwest Atlantic occur from Florida to 
eastern Newfoundland. The species has an apparent preference for steep, 
shelf-edge habitats between about 400 to 1,000 m (1,312 to 3,280 ft) 
deep (Baird 2009). Risso's dolphin of the western North Atlantic stock 
prefers temperate to tropical waters typically from 15 to 20 [deg]C (59 
to 68 [deg]F) and are rarely found in waters below 10 [deg]C (50 
[deg]F). Off the northeastern U.S. coast, Risso's dolphins are 
distributed along the continental shelf edge from Cape Hatteras 
northward to Georges Bank during spring, summer, and autumn. In winter, 
the range is in the mid-Atlantic Bight and extends outward into oceanic 
waters. In general, the population occupies the mid-Atlantic 
continental shelf edge year round (Hayes et al. 2019).

Harbor Porpoise

    The harbor porpoise inhabits shallow, coastal waters, often found 
in bays, estuaries, and harbors. In the western Atlantic, they are 
found from Cape Hatteras north to Greenland. During summer (July to 
September), harbor porpoises are concentrated in the northern Gulf of 
Maine and southern Bay of Fundy region, generally in waters less than 
150 m deep with a few sightings in the upper Bay of Fundy and on 
Georges Bank. During fall (October-December) and spring (April-June), 
harbor porpoises are widely dispersed from New Jersey to Maine, with 
lower densities farther north and south. They are seen from the 
coastline to deep waters (>1,800 m) although the majority of the 
population is found over the continental shelf. The harbor porpoise is 
likely to occur in the waters of the mid-Atlantic during winter months, 
as this species prefers cold temperate and subarctic waters (Hayes et 
al. 2019). Harbor porpoise generally move out of the Mid-Atlantic 
during spring, migrating north to the Gulf of Maine. There does not 
appear to be a temporally coordinated migration or a specific migratory 
route to and from the Bay of Fundy region (Hayes et al. 2018).

Harbor Seal

    Harbor seals are the most abundant seals in the waters of the 
eastern United States and are commonly found in all nearshore waters of 
the Atlantic Ocean from Newfoundland, Canada southward to northern 
Florida (Hayes et al. 2019). While harbor seals occur year-round north 
of Cape Cod, they only occur south of Cape Cod (southern New England to 
New Jersey) during winter migration, typically September through May 
(Kenney and Vigness-Raposa 2010; Hayes et al. 2019). During the summer, 
most harbor seals can be found north of Massachusetts within the 
coastal waters of central and northern Maine as well as the Bay of 
Fundy (Hayes et al. 2019).
    Since July 2018, elevated numbers of harbor seal and gray seal 
mortalities have occurred across Maine, New Hampshire and 
Massachusetts. This event has been declared a UME. Additionally, 
stranded seals have shown clinical signs as far south as Virginia, 
although not in elevated numbers. Therefore the UME investigation now 
encompasses all seal strandings from Maine to Virginia. As of March, 
2020 there a total of 3,152 reported strandings (of all species), 
though only 10 occurred in Virginia while 8 were recorded in Maryland. 
Full or partial necropsy examinations have been conducted on some of 
the seals and samples have been collected for testing. Based on tests 
conducted thus far, the main pathogen found in the seals is phocine 
distemper virus. NMFS is performing additional testing to identify any 
other factors that may be involved in this UME. Information on this UME 
is available online at: www.fisheries.noaa.gov/new-england-mid-atlantic/marine-life-distress/2018-2020-pinniped-unusual-mortality-event-along.

Gray Seal

    The gray seal occurs on both coasts of the Northern Atlantic Ocean 
and are divided into three major populations (Hayes et al. 2019). The 
western north Atlantic stock occurs in eastern Canada and the 
northeastern United States, occasionally as far south as North 
Carolina. Gray seals inhabit rocky coasts and islands, sandbars, ice 
shelves and icebergs (Hayes et al. 2019). In the United States, gray 
seals congregate in the summer to give birth at four established 
colonies in Massachusetts and Maine (Hayes et al. 2019). From September 
through May, they disperse and can be abundant as far south as New 
Jersey. The range of gray seals appears to be shifting as they are 
regularly being reported further south than they were historically 
(Rees et al. 2016).
    Gray seals are uncommon in Virginia and the Chesapeake Bay. Only 15 
gray seal strandings were documented in Virginia from 1988 through 2013 
(Barco and Swingle 2014). They are rarely found resting on the rocks 
around the portal islands of the Chesapeake Bay Bridge Tunnel (CBBT) 
from December through April alongside harbor seals. Seal observation 
surveys conducted at the CBBT recorded one gray seal in each of the 
2014/2015 and 2015/2016 seasons while no gray seals were reported 
during the 2016/2017 and 2017/2018 seasons (Rees et al. 2016, Jones et 
al. 2018).

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et al. 
1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect 
this, Southall et al. (2007) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 3.

           Table 3--Marine Mammal Hearing Groups (NMFS, 2018)
------------------------------------------------------------------------
               Hearing group                 Generalized hearing range*
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen        7 Hz to 35 kHz.
 whales).

[[Page 36546]]

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

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al. 2006; Kastelein et al. 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Sixteen marine mammal species (14 cetacean and 2 pinniped (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, five are classified as low-frequency cetaceans 
(i.e., all mysticete species), eight are classified as mid-frequency 
cetaceans (i.e., all delphinid species and the sperm whale), and one is 
classified as a high-frequency cetacean (i.e., harbor porpoise).

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 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 Sound Sources

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used in this 
proposal inasmuch as the information is relevant to the specified 
activity and to a discussion of the potential effects of the specified 
activity on marine mammals found later in this document. For general 
information on sound and its interaction with the marine environment, 
please see, e.g., Au and Hastings (2008); Richardson et al. (1995).
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz (Hz) or cycles per second. Wavelength is the 
distance between two peaks or corresponding points of a sound wave 
(length of one cycle). Higher frequency sounds have shorter wavelengths 
than lower frequency sounds, and typically attenuate (decrease) more 
rapidly, except in certain cases in shallower water. Amplitude is the 
height of the sound pressure wave or the ``loudness'' of a sound and is 
typically described using the relative unit of the decibel (dB). A 
sound pressure level (SPL) in dB is described as the ratio between a 
measured pressure and a reference pressure (for underwater sound, this 
is 1 microPascal ([mu]Pa)), and is a logarithmic unit that accounts for 
large variations in amplitude; therefore, a relatively small change in 
dB corresponds to large changes in sound pressure. The source level 
(SL) represents the SPL referenced at a distance of 1 m from the source 
(referenced to 1 [mu]Pa), while the received level is the SPL at the 
listener's position (referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average. Root mean square accounts for both positive 
and negative values; squaring the pressures makes all values positive 
so that they may be accounted for in the summation of pressure levels 
(Hastings and Popper, 2005). This measurement is often used in the 
context of discussing behavioral effects, in part because behavioral 
effects, which often result from auditory cues, may be better expressed 
through averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa\2\-s) 
represents the total energy in a stated frequency band over a stated 
time interval or event, and considers both intensity and duration of 
exposure. The per-pulse SEL is calculated over the time window 
containing the entire pulse (i.e., 100 percent of the acoustic energy). 
SEL is a cumulative metric; it can be accumulated over a single pulse, 
or calculated over periods containing multiple pulses. Cumulative SEL 
represents the total energy accumulated by a receiver over a defined 
time window or during an event. Peak sound pressure (also referred to 
as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source, and is represented in the same units as the rms sound pressure.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or may radiate in all directions 
(omnidirectional sources). The compressions and decompressions 
associated with sound waves are detected as changes in pressure by 
aquatic life and man-made sound receptors such as hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound, which is 
defined as environmental background sound levels lacking a single 
source or point (Richardson et al. 1995). The sound level of a region 
is defined by the total acoustical energy being generated by known and 
unknown sources. These sources may include physical (e.g., wind and 
waves, earthquakes, ice, atmospheric sound), biological (e.g.,

[[Page 36547]]

sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic (e.g., vessels, dredging, construction) sound. A number 
of sources contribute to ambient sound, including wind and waves, which 
are a main source of naturally occurring ambient sound for frequencies 
between 200 hertz (Hz) and 50 kilohertz (kHz) (Mitson, 1995). In 
general, ambient sound levels tend to increase with increasing wind 
speed and wave height. Precipitation can become an important component 
of total sound at frequencies above 500 Hz, and possibly down to 100 Hz 
during quiet times. Marine mammals can contribute significantly to 
ambient sound levels, as can some fish and snapping shrimp. The 
frequency band for biological contributions is from approximately 12 Hz 
to over 100 kHz. Sources of ambient sound related to human activity 
include transportation (surface vessels), dredging and construction, 
oil and gas drilling and production, geophysical surveys, sonar, and 
explosions. Vessel noise typically dominates the total ambient sound 
for frequencies between 20 and 300 Hz. In general, the frequencies of 
anthropogenic sounds are below 1 kHz and, if higher frequency sound 
levels are created, they attenuate rapidly.
    The sum of the various natural and anthropogenic sound sources that 
comprise ambient sound at any given location and time depends not only 
on the source levels (as determined by current weather conditions and 
levels of biological and human activity) but also on the ability of 
sound to propagate through the environment. In turn, sound propagation 
is dependent on the spatially and temporally varying properties of the 
water column and sea floor, and is frequency-dependent. As a result of 
the dependence on a large number of varying factors, ambient sound 
levels can be expected to vary widely over both coarse and fine spatial 
and temporal scales. Sound levels at a given frequency and location can 
vary by 10-20 decibels (dB) from day to day (Richardson et al. 1995). 
The result is that, depending on the source type and its intensity, 
sound from the specified activity may be a negligible addition to the 
local environment or could form a distinctive signal that may affect 
marine mammals.
    Sounds are often considered to fall into one of two general types: 
Pulsed and non-pulsed. The distinction between these two sound types is 
important because they have differing potential to cause physical 
effects, particularly with regard to hearing (e.g., Ward, 1997 in 
Southall et al. 2007). Please see Southall et al. (2007) for an in-
depth discussion of these concepts. The distinction between these two 
sound types is not always obvious, as certain signals share properties 
of both pulsed and non-pulsed sounds. A signal near a source could be 
categorized as a pulse, but due to propagation effects as it moves 
farther from the source, the signal duration becomes longer (e.g., 
Greene and Richardson, 1988).
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or intermittent (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems. The 
duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.

Potential Effects of Underwater Sound

    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.
    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 (i.e., certain non-auditory 
physical or physiological effects) only briefly as we do not expect 
that there is a reasonable likelihood that HRG surveys may 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 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.
    Threshold Shift--Note that, in the following discussion, we refer 
in many cases to a review article concerning studies of noise-induced 
hearing loss

[[Page 36548]]

conducted from 1996-2015 (i.e., Finneran, 2015). Marine mammals exposed 
to high-intensity sound, or to lower-intensity sound for prolonged 
periods, can experience hearing threshold shift (TS), which is the loss 
of hearing sensitivity at certain frequency ranges (Finneran, 2015). TS 
can be permanent (PTS), in which case the loss of hearing sensitivity 
is not fully recoverable, or temporary (TTS), in which case the 
animal's hearing threshold would recover over time (Southall et al. 
2007). Repeated sound exposure that leads to TTS could cause PTS. In 
severe cases of PTS, there can be total or partial deafness, while in 
most cases the animal has an impaired ability to hear sounds in 
specific frequency ranges (Kryter, 1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al. 2007). In addition, other 
investigators have suggested that TTS is within the normal bounds of 
physiological variability and tolerance and does not represent physical 
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to 
constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans, but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al. 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al. 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulse sounds (such as impact pile driving 
pulses as received close to the source) are at least 6 dB higher than 
the TTS threshold on a peak-pressure basis and PTS cumulative sound 
exposure level thresholds are 15 to 20 dB higher than TTS cumulative 
sound exposure level thresholds (Southall et al. 2007). Given the 
higher level of sound or longer exposure duration necessary to cause 
PTS as compared with TTS, it is considerably less likely that PTS could 
occur.
    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.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin, beluga whale (Delphinapterus leucas), harbor 
porpoise, and Yangtze finless porpoise (Neophocoena asiaeorientalis)) 
and three species of pinnipeds (northern elephant seal (Mirounga 
angustirostris), harbor seal, and California sea lion (Zalophus 
californianus)) exposed to a limited number of sound sources (i.e., 
mostly tones and octave-band noise) in laboratory settings (Finneran, 
2015). TTS was not observed in trained spotted (Phoca largha) and 
ringed (Pusa hispida) seals exposed to impulsive noise at levels 
matching previous predictions of TTS onset (Reichmuth et al. 2016). In 
general, harbor seals and harbor porpoises have a lower TTS onset than 
other measured pinniped or 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. 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 (2018).
    Animals in the Survey Area during the proposed survey are unlikely 
to incur TTS due to the characteristics of the sound sources, which 
include relatively low source levels and generally very short pulses 
and duration of the sound. Even for high-frequency cetacean species 
(e.g., harbor porpoises), which may have increased sensitivity to TTS 
(Lucke et al. 2009; Kastelein et al. 2012b), individuals would have to 
make a very close approach and also remain very close to vessels 
operating these sources in order to receive multiple exposures at 
relatively high levels, as would be necessary to cause TTS. 
Intermittent exposures--as would occur due to the brief, transient 
signals produced by these sources--require a higher cumulative SEL to 
induce TTS than would continuous exposures of the same duration (i.e., 
intermittent exposure results in lower levels of TTS) (Mooney et al. 
2009a; Finneran et al. 2010). Moreover, most marine mammals would more 
likely avoid a loud sound source rather than swim in such close 
proximity as to result in TTS. Kremser et al. (2005) noted that the 
probability of a cetacean swimming through the area of exposure when a 
sub-bottom profiler emits a pulse is small--because if the animal was 
in the area, it would have to pass the transducer at close range in 
order to be subjected to sound levels that could cause TTS and would 
likely exhibit avoidance behavior to the area near the transducer 
rather than swim through at such a close range. Further, the restricted 
beam shape of the majority of the geophysical survey equipment proposed 
for use makes it unlikely that an animal would be exposed more than 
briefly during the passage of the vessel.
    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

[[Page 36549]]

sources, distance from the source). Please see Appendices B-C of 
Southall et al. (2007) for a review of studies involving marine mammal 
behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al. 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al. 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. As noted, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al. 
1995; NRC, 2003; Wartzok et al. 2003). Controlled experiments with 
captive marine mammals have showed pronounced behavioral reactions, 
including avoidance of loud sound sources (Ridgway et al. 1997; 
Finneran et al. 2003). Observed responses of wild marine mammals to 
loud pulsed sound sources (typically 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 low-frequency airgun source vessels with no 
apparent discomfort or obvious behavioral change (e.g., Barkaszi et al. 
2012), indicating the importance of frequency output in relation to the 
species' hearing sensitivity.
    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; Costa et al. 2003; Ng and Leung, 2003; Nowacek et al.; 
2004; Goldbogen et al. 2013a, 2013b). 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.
    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).
    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 airgun surveys (Malme et al. 1984). 
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., Blackwell et al. 2004; 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

[[Page 36550]]

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.
    We expect that some marine mammals may exhibit behavioral responses 
to the HRG survey activities in the form of avoidance of the area 
during the activity, especially the naturally shy harbor porpoise, 
while others such as delphinids might be attracted to the survey 
activities out of curiosity. However, because the HRG survey equipment 
operates from a moving vessel, and the maximum radius to the Level B 
harassment threshold is relatively small, the area and time that this 
equipment would be affecting a given location is very small. Further, 
once an area has been surveyed, it is not likely that it will be 
surveyed again, thereby reducing the likelihood of repeated impacts 
within the Survey Area.
    We have also considered the potential for severe behavioral 
responses such as stranding and associated indirect injury or mortality 
from Dominion's use of HRG survey equipment. Previous commenters have 
referenced a 2008 mass stranding of approximately 100 melon-headed 
whales in a Madagascar lagoon system. An investigation of the event 
indicated that use of a high-frequency mapping system (12-kHz multibeam 
echosounder) was the most plausible and likely initial behavioral 
trigger of the event, while providing the caveat that there is no 
unequivocal and easily identifiable single cause (Southall et al. 
2013). The investigatory panel's conclusion was based on (1) very close 
temporal and spatial association and directed movement of the survey 
with the stranding event; (2) the unusual nature of such an event 
coupled with previously documented apparent behavioral sensitivity of 
the species to other sound types (Southall et al. 2006; Brownell et al. 
2009); and (3) the fact that all other possible factors considered were 
determined to be unlikely causes. Specifically, regarding survey 
patterns prior to the event and in relation to bathymetry, the vessel 
transited in a north-south direction on the shelf break parallel to the 
shore, ensonifying large areas of deep-water habitat prior to operating 
intermittently in a concentrated area offshore from the stranding site; 
this may have trapped the animals between the sound source and the 
shore, thus driving them towards the lagoon system. The investigatory 
panel systematically excluded or deemed highly unlikely nearly all 
potential reasons for these animals leaving their typical pelagic 
habitat for an area extremely atypical for the species (i.e., a shallow 
lagoon system). Notably, this was the first time that such a system has 
been associated with a stranding event. The panel also noted several 
site- and situation-specific secondary factors that may have 
contributed to the avoidance responses that led to the eventual 
entrapment and mortality of the whales. Specifically, shoreward-
directed surface currents and elevated chlorophyll levels in the area 
preceding the event may have played a role (Southall et al. 2013). The 
report also notes that prior use of a similar system in the general 
area may have sensitized the animals and also concluded that, for 
odontocete cetaceans that hear well in higher frequency ranges where 
ambient noise is typically quite low, high-power active sonars 
operating in this range may be more easily audible and have potential 
effects over larger areas than low frequency systems that have more 
typically been considered in terms of anthropogenic noise impacts. It 
is, however, important to note that the relatively lower output 
frequency, higher output power, and complex nature of the system 
implicated in this event, in context of the other factors noted here, 
likely produced a fairly unusual set of circumstances that indicate 
that such events would likely remain rare and are not necessarily 
relevant to use of lower-power, higher-frequency systems more commonly 
used for HRG survey applications. The risk of similar events recurring 
is likely very low, given the extensive use of active acoustic systems 
used for scientific and navigational purposes worldwide on a daily 
basis and the lack of direct evidence of such responses previously 
reported.
    Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of

[[Page 36551]]

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 
sufficient 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).
    NMFS does not expect that the generally short-term, intermittent, 
and transitory HRG activities would create conditions of long-term, 
continuous noise and chronic acoustic exposure leading to long-term 
physiological stress responses in marine mammals.
    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 
if disrupting behavioral patterns. 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.
    Marine mammal communications would not likely be masked appreciably 
by the HRG equipment given the directionality of the signals (for most 
geophysical survey equipment types proposed for use (Table 1)) and the 
brief period when an individual mammal is likely to be within its beam.

Vessel Strike

    Vessel strikes of marine mammals can cause significant wounds, 
which may lead to the death of the animal. An animal at the surface 
could be struck directly by a vessel, a surfacing animal could hit the 
bottom of a vessel, or a vessel's propeller could injure an animal just 
below the surface. The severity of injuries typically depends on the 
size and speed of the vessel (Knowlton and Kraus 2001; Laist et al. 
2001; Vanderlaan and Taggart 2007).
    The most vulnerable marine mammals are those that spend extended 
periods of time at the surface in order to restore oxygen levels within 
their tissues after deep dives (e.g., the sperm whale). In addition, 
some baleen whales, such as the North Atlantic right whale, seem 
generally unresponsive to vessel sound, making them more susceptible to 
vessel collisions (Nowacek et al. 2004). These species are primarily 
large, slow moving whales. Smaller marine mammals (e.g., bottlenose 
dolphin) move quickly through the water column and are often seen 
riding the bow wave of large ships. Marine mammal responses to vessels 
may include avoidance and changes in dive pattern (NRC 2003).
    An examination of all known ship strikes from all shipping sources 
(civilian and military) indicates vessel speed is a principal factor in 
whether a vessel strike results in death (Knowlton and Kraus 2001; 
Laist et al. 2001; Jensen and Silber 2003; Vanderlaan and Taggart 
2007). In assessing records with

[[Page 36552]]

known vessel speeds, Laist et al. (2001) found a direct relationship 
between the occurrence of a whale strike and the speed of the vessel 
involved in the collision. The authors concluded that most deaths 
occurred when a vessel was traveling in excess of 24.1 km/h (14.9 mph; 
13 kn). Given the slow vessel speeds and predictable course necessary 
for data acquisition, ship strike is unlikely to occur during the 
geophysical surveys. Marine mammals would be able to easily avoid the 
survey vessel due to the slow vessel speed. Further, Dominion would 
implement measures (e.g., protected species monitoring, vessel speed 
restrictions and separation distances; see Proposed Mitigation) set 
forth in the BOEM lease to reduce the risk of a vessel strike to marine 
mammal species in the Survey Area.

Anticipated Effects on Marine Mammal Habitat

    The proposed activities would not result in permanent impacts to 
habitats used directly by marine mammals, but may have potential minor 
and short-term impacts to food sources such as forage fish. The 
proposed activities could affect acoustic habitat (see masking 
discussion above), but meaningful impacts are unlikely. There are no 
feeding areas, rookeries, or mating grounds known to be biologically 
important to marine mammals within the proposed Survey Area with the 
exception of migratory BIA for right whales which was described 
previously. The HRG survey equipment will not contact the substrate and 
does not represent a source of pollution. Impacts to substrate or from 
pollution are therefore not discussed further.
    Effects to Prey--Sound may affect marine mammals through impacts on 
the abundance, behavior, or distribution of prey species (e.g., 
crustaceans, cephalopods, fish, zooplankton). Marine mammal prey varies 
by species, season, and location and, for some, is not well documented. 
Here, we describe studies regarding the effects of noise on known 
marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick et al. 1999; Fay, 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear sounds using pressure and 
particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al. 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to noise depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005) identified several studies that suggest fish 
may relocate to avoid certain areas of sound energy. Several studies 
have demonstrated that impulse sounds might affect the distribution and 
behavior of some fishes, potentially impacting foraging opportunities 
or increasing energetic costs (e.g., Fewtrell and McCauley, 2012; 
Pearson et al. 1992; Skalski et al. 1992; Santulli et al. 1999; Paxton 
et al. 2017). However, some studies have shown no or slight reaction to 
impulse sounds (e.g., Pena et al. 2013; Wardle et al. 2001; Jorgenson 
and Gyselman, 2009; Cott et al. 2012). More commonly, though, the 
impacts of noise on fish are temporary.
    We are not aware of any available literature on impacts to marine 
mammal prey from sound produced by HRG survey equipment. However, as 
the HRG survey equipment introduces noise to the marine environment, 
there is the potential for it to result in avoidance of the area around 
the HRG survey activities on the part of marine mammal prey. The 
duration of fish avoidance of an area after HRG surveys depart the area 
is unknown, but a rapid return to normal recruitment, distribution and 
behavior is anticipated. In general, impacts to marine mammal prey 
species are expected to be minor and temporary due to the expected 
short daily duration of the proposed HRG survey, the fact that the 
proposed survey is mobile rather than stationary, and the relatively 
small areas potentially affected. The areas likely impacted by the 
proposed activities are relatively small compared to the available 
habitat in the Atlantic Ocean. Any behavioral avoidance by fish of the 
disturbed area would still leave significantly large areas of fish and 
marine mammal foraging habitat in the nearby vicinity. Based on the 
information discussed herein, we conclude that impacts of the specified 
activity are not likely to have more than short-term adverse effects on 
any prey habitat or populations of prey species. Because of the 
temporary nature of the disturbance, and the availability of similar 
habitat and resources (e.g., prey species) in the surrounding area, any 
impacts to marine mammal habitat are not expected to result in 
significant or long-term consequences for individual marine mammals, or 
to contribute to adverse impacts on their populations. Effects to 
habitat will not be discussed further in this document.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers'' and the negligible impact 
determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would be by Level B harassment only, in the form 
of disruption of behavioral patterns for individual marine mammals 
resulting from exposure to HRG sources. Based on the nature of the 
activity and the anticipated effectiveness of the mitigation measures 
(i.e., exclusion zones and shutdown measures), discussed in detail 
below in Proposed Mitigation section, Level A harassment is neither 
anticipated nor proposed to be authorized.
    As described previously, no mortality is anticipated or proposed to 
be authorized for this activity. Below we describe how the take is 
estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which NMFS believes the best available science 
indicates marine mammals will be behaviorally harassed or incur some 
degree of permanent hearing impairment; (2) the area or volume of water 
that will be ensonified above these levels in a day; (3) the density or 
occurrence of marine mammals within these ensonified areas; and, (4) 
and the number of days of activities. We note that while these basic 
factors can contribute to a basic

[[Page 36553]]

calculation to provide an initial prediction of takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the proposed take estimate.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al. 2007, Ellison 
et al. 2012). Based on what the available science indicates and the 
practical need to use a threshold based on a factor that is both 
predictable and measurable for most activities, NMFS uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS predicts that marine mammals are likely to 
be behaviorally harassed in a manner we consider Level B harassment 
when exposed to underwater anthropogenic noise above received levels of 
120 dB re 1 [mu]Pa (rms) for continuous (e.g., vibratory pile-driving) 
and above 160 dB re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., 
seismic airguns) or intermittent (e.g., scientific sonar) sources.
    Dominion's proposed activity includes the use of intermittent 
(geophysical survey equipment) sources, and therefore the 160 dB re 1 
[mu]Pa (rms) threshold is applicable.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (NMFS, 2018) identifies dual criteria to 
assess auditory injury (Level A harassment) to five different marine 
mammal groups (based on hearing sensitivity) as a result of exposure to 
noise from two different types of sources (impulsive or non-impulsive). 
The components of Dominion's proposed activity that may result in the 
take of marine mammals include the use of both impulsive and non-
impulsive sources (geophysical survey equipment).
    These thresholds are provided in Table 4 below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS 2018 Technical Guidance, which may be accessed at 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

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

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    When the NMFS Technical Guidance (2016) was published, in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a User Spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which may result in some degree of 
overestimate of Level A harassment 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 survey vessels 
operating HRG equipment, 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. 
Inputs used in the User Spreadsheet are shown in Table 5 and the 
resulting Level A harassment isopleths are reported below in Table 6.
    Note that NMFS considers the data provided by Crocker and 
Fratantonio (2016) to represent the best available information on 
source levels associated with HRG equipment and therefore recommends 
that source levels provided by Crocker and Fratantonio (2016) be 
incorporated in the method described above to estimate isopleth 
distances to the Level B harassment threshold. In

[[Page 36554]]

cases when the source level for a specific type of HRG equipment is not 
provided in Crocker and Fratantonio (2016), NMFS recommends that either 
the source levels provided by the manufacturer be used, or, in 
instances where source levels provided by the manufacturer are 
unavailable or unreliable, a proxy from Crocker and Fratantonio (2016) 
be used instead. Table 1 shows the HRG equipment types that may be used 
during the proposed surveys, the sound levels associated with those HRG 
equipment types, and the literature sources for the sound source levels 
contained in Table 5.

                                                                                                    Table 5--User Spreadsheet Inputs
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
           HRG system                              Subsea positioning/USBL                         Multibeam       Side scan sonar      Parametric SBP              Non-parametric SBP                  Medium-penetration seismic
---------------------------------------------------------------------------------------------     echosounder    -----------------------------------------------------------------------------------------------------------------------
                                                                                             --------------------                                                                                   Geo Marine Dual    Applied Acoustics
          HRG Equipment           Sonardyne Ranger 2    Evologics 82CR        IxBlue GAPS                         Edgetech 4200 dual   Innomar SES-2000   Edgetech 216 Chirp  Edgetech 512 Chirp     400 GeoSource      S-Boom (Triple
                                                                                                R2 Sonics 2026         frequency                                                                     Sparker 800j        Plate Boomer)
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Spreadsheet Tab Used............                                                          D.1: MOBILE SOURCE: Non-Impulsive, Intermittent
                                      F.1: MOBILE SOURCE: Impulsive,
                                               Intermittent.
                                 -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Source Level....................  188 RMS...........  178 RMS...........  191 RMS...........  191 RMS...........  206 RMS...........  241 RMS...........  193 RMS...........  177 RMS...........  200 RMS/210 PK....  203RMS/213 PK.
Weighting Factor Adjustment       35/55.............  48/78.............  20/30.............  170...............  100...............  2/22..............  2/16..............  0.5/12............  0.25/4............  0.5.
 (kHz).
Source Velocity (m/sec).........  2.045.............  2.045.............  2.045.............  2.045.............  2.045.............  2.045.............  2.045.............  2.045.............  2.045.............  2.045.
Pulse Duration (seconds)........  0.001.............  0.6...............  0.011.............  0.01115...........  0.01..............  0.001.............  0.001.............  0.02..............  0.0008............  0.01.
1/repetition rate[supcaret]       0.33..............  1.................  1.................  0.016667..........  0.125.............  2.................  0.25..............  0.25..............  0.55..............  0.25.
 (seconds.
Propagation (xLogR).............  20................  20................  20................  20................  20................  20................  20................  20................  20................  20.
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


                           Table 6 -- Distances (Meters) to Level A Harassment Regulatory Thresholds by Equipment Category\1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                      Marine Mammal Group PTS Onset
                                                --------------------------------------------------------------------------------------------------------
          HRG system            Representative       LF cetaceans         MF cetaceans         HF cetaceans       Phocid pinnipeds    Otariid pinnipeds
                                 HRG equipment  --------------------------------------------------------------------------------------------------------
                                                    199 dB SELcum        198 dB SELcum        173 dB SELcum        201 dB SELcum        219 dB SELcum
--------------------------------------------------------------------------------------------------------------------------------------------------------
Multibeam Echosounder........  R2Sonics 2026...  0..................  0..................  14.4...............  0..................  0.
Synthetic Aperture Sonar,      Kraken Aquapix    N/A................  N/A................  N/A................  N/A................  N/A.
 combined bathymetry/sidescan.  \2\.
Sidescan Sonar...............  Edgetech 4200     N/A................  N/A................  N/A................  N/A................  N/A.
                                dual Frequency
                                \2\.
Parametric SBP...............  Innomar SES-2000  12.1...............  14.7...............  3,950..............  4.8................  0.1.
                                Medium 100.
Non-Parametric SBP...........  Edgetech 216      0..................  0..................  0.4................  0..................  0.
                                Chirp.
                               Edgetech 512      0..................  0..................  0.1................  0..................  0.
                                Chirp.
Medium Penetration Seismic...  Geo Marine Dual   0.1................  0..................  1.5................  0.1................  0.
                                400 Sparker
                                800J.
                               Applied           5.9................  0.2................  54.2...............  3.5................  0.1.
                                Acoustics S-
                                Boom (Triple
                                Plate Boomer
                                1000J).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Distances to the Level A harassment threshold based on the larger of the dual criteria (peak SPL and SELcum) are shown.
\2\ Operating frequency above 180 kHz exceeding upper range of marine mammal hearing.

    Note that take of marine mammals through use of the non-impulsive, 
intermittent sources shown in Table 5, such as the Innomar SES-2000 
Medium 100 device, is highly unlikely. See estimated Level B harassment 
isopleth distances in Table 7. The estimated Level A harassment 
isopleths (Table 6) are based on the best currently available tools and 
information, but given aspects of these sources' output (e.g., beam 
width) that cannot readily be accounted for in the user guidance 
spreadsheet, these calculated zones should not be interpreted 
literally. These isopleths are provided only as a reference, 
interpreted in context of our qualitative understanding of the risk 
posed through use of these sources when evaluating potential for Level 
A harassment. In consideration of the foregoing, and in consideration 
of the proposed mitigation measures (see the Proposed Mitigation 
section for more detail), the likelihood of the proposed survey 
resulting in take in the form of Level A harassment is considered so 
low as to be discountable; therefore, NMFS does not propose to 
authorize take of any marine mammals by Level A harassment.
    NMFS has developed an interim methodology for determining the rms 
sound pressure level (SPLrms) at the 160-dB isopleth for the purposes 
of estimating take by Level B harassment resulting from exposure to HRG 
survey equipment that takes into account source level, beamwidth, water 
depth, absorption, and operating frequency

[[Page 36555]]

(NMFS 2019). Distances to the behavioral threshold are shown in Table 
7.

   Table 7--HRG Equipment--Distances to Regulatory Level B Harassment
                               Thresholds
------------------------------------------------------------------------
                                                       Lateral distance
                                     Source level       (m) to level B
      HRG survey equipment          (SLRMS) (dB re    thresholds used in
                                       1[mu]Pa)          take analysis
------------------------------------------------------------------------
R2Sonics 2026...................  191...............  0.3.
Kraken Aquapix\1\...............  N/A...............  N/A.
Edgetech 4200 dual frequency\1\.  N/A...............  N/A.
Innomar SES-2000 Medium 100.....  241...............  0.7.
Edgetech 216 Chirp..............  193...............  10.2.
Edgetech 512 Chirp..............  177...............  2.4.
Geo Marine Dual 400 Sparker 800J  200...............  100.0.
Triple Plate Boomer 1000J.......  203...............  21.9.
------------------------------------------------------------------------
\1\ Operating frequency above 180 kHz, above upper range of marine
  mammal hearing.

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 harassment, radial 
distances to predicted isopleths corresponding to harassment thresholds 
are calculated, as described above. Those distances are then used to 
calculate the area(s) around the HRG survey equipment predicted to be 
ensonified to sound levels that exceed harassment thresholds. The area 
estimated to be ensonified to relevant thresholds in a single day is 
then calculated, based on areas predicted to be ensonified around the 
HRG survey equipment and the estimated trackline distance traveled per 
day by the survey vessel.
    The predominant source is the Geo Marine Dual 400 Sparker 800J (see 
Table 7), which results in the furthest distance to the Level B 
harassment criteria (160 dBRMS90 re 1 [mu]Pa) at 
100.0 m (328 ft). This source will be employed on an estimated 152 
vessel days. During an additional 9 vessel days, the Triple Plate 
Boomer 1000J would be the predominant source used, with an estimated 
Level B harassment threshold of 22 m (72 ft) as the basis for 
determining potential take.
    The basis for the take estimate is the number of times that marine 
mammals are predicted to be exposed to sound levels in excess of Level 
B harassment criteria. Typically, this is determined by multiplying the 
ZOI out to the Level B harassment criteria isopleth by local marine 
mammal density estimates and then correcting for seasonal use by marine 
mammals, seasonal duration of project-specific noise-generating 
activities, and estimated duration of individual activities when the 
maximum noise-generating activities are intermittent or occasional. In 
the absence of any part of this information, it becomes prudent to take 
a conservative approach to ensure the potential number of takes is not 
greatly underestimated. The estimated distance of the daily vessel 
trackline was determined using the estimated average speed of the 
vessel and the 24-hour operational period within each of the 
corresponding survey segments. Using the distance of 100.0 m (328 ft) 
and 22 m (72 ft) to the 160 dB Level B harassment isopleths for when 
HRG equipment is in use, the estimated daily vessel track of 
approximately 121.54 km (75.5 mi) for 24-hour operations, inclusive of 
an additional circular area to account for radial distance at the start 
and end of a 24-hour cycle, gives estimates of incidental take by HRG 
survey equipment based on the ensonified area around the survey 
equipment as depicted in Table 7.
    Based on the maximum estimated distance to the Level B harassment 
threshold of 100 m (Table 7) and the maximum estimated daily track line 
distance of 121.54 km, an area of 24.34 km\2\ would be ensonified to 
the Level B harassment threshold per day during the 152 vessel days 
that the Geo Marine Dual 400 Sparker 800J is in use. The estimated 
Level B harassment threshold of 22 m (72 ft) associated with the Triple 
Plate Boomer 1000J would ensonify 5.35 km\2\ for 9 vessel days.

                   Table 8--Survey Segment Distances and ZOIs at Level B Harassment Distances
----------------------------------------------------------------------------------------------------------------
                                                                     Number of       Estimated    Calculated ZOI
                         Survey segment                            active survey   distances per      per day
                                                                    vessel days      day (km)         (km\2\)
----------------------------------------------------------------------------------------------------------------
Lease Area Survey (Sparker In Use)..............................             149          121.54           24.34
Export Cable Corridor Survey (Sparker In Use)...................               3
Export Cable Corridor Survey (No Sparker In Use)................               9            5.35
----------------------------------------------------------------------------------------------------------------

    The number of marine mammals expected to be incidentally taken per 
day is then calculated by estimating the number of each species 
predicted to occur within the daily ensonified area (animals/km\2\) by 
incorporating the estimated marine mammal densities.
    A summary of this method is illustrated in the following formula:

Estimated Take = D x ZOI x # of days

    Where:

D = average species density (per km\2\) and ZOI = maximum daily 
ensonified area to relevant thresholds.

    The habitat-based density models produced by the Duke University 
Marine Geospatial Ecology Laboratory (Roberts et al. 2016, 2017, 2018) 
represent the best available information regarding marine mammal 
densities in the proposed Survey Area. The density data presented by 
Roberts et al. (2016, 2017, 2018) incorporates aerial and shipboard 
line-transect survey data from NMFS and other organizations and 
incorporates data from 8 physiographic and 16 dynamic oceanographic and

[[Page 36556]]

biological covariates, and controls for the influence of sea state, 
group size, availability bias, and perception bias on the probability 
of making a sighting. These density models were originally developed 
for all cetacean taxa in the U.S. Atlantic (Roberts et al. 2016). In 
subsequent years, certain models have been updated on the basis of 
additional data as well as certain methodological improvements. More 
information is available online at seamap.env.duke.edu/models/Duke-EC-GOM-2015/. Marine mammal density estimates in the Survey Area (animals/
km\2\) were obtained using these model results (Roberts et al. 2016, 
2017, 2018).
    For the purposes of exposure analysis density data from Roberts et 
al. (2016, 2017, and 2018) were mapped within the boundary of the 
Survey Area for each segment using geographic information systems. For 
each survey segment, the maximum densities as reported by Roberts et 
al. (2016, 2017, and 2018), were averaged by season over the survey 
duration (for spring, summer, fall and winter) for the entire HRG 
Survey Area based on the proposed HRG survey schedule. The maximum 
average seasonal density within the HRG survey schedule was then 
selected for inclusion in the take calculations. Note that recently, 
these data have been updated with new modeling results and have 
included density estimates for pinnipeds (Roberts et al. 2016; 2017; 
2018). For pinnipeds, because the seasonality of, and habitat use by, 
gray seals roughly overlaps with harbor seals, the same estimated 
abundance has been applied to both gray and harbor seals.

                        Table 9--Total Numbers of Potential Incidental Take of Marine Mammals Proposed for Authorization and Proposed Takes as a Percentage of Population
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                            Lease area             Cable route corridor (sparker     Cable route corridor (no             Adjusted totals
                                                                 --------------------------------             in use)                     sparker in use)        -------------------------------
                                                                                                 ----------------------------------------------------------------
                                                                      Average                         Average                         Average
                                                                     seasonal       Calc. take       seasonal                        seasonal                          Take        Percentage of
                                                                    density \1\        (No.)        density \1\     Calc. take      density \1\     Calc. take     authorization  population \5\
                                                                     (No./100                        (No./100          (No.)         (No./100          (No.)           (No.)
                                                                     km[sup2])                       km[sup2])                       km[sup2])
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale......................................           0.078           2.816           0.049           0.036           0.049           0.023           \4\ 2            0.37
Humpback whale..................................................           0.085           3.087           0.066           0.048           0.066           0.032           \4\ 3            0.18
Fin whale.......................................................           0.261           9.448           0.122           0.089           0.122           0.059          \4\ 10            0.21
Sei whale.......................................................           0.002           0.089           0.001           0.000           0.001           0.000           \4\ 1            0.15
Sperm whale.....................................................           0.007           0.238           0.002           0.002           0.002           0.001           \4\ 1            0.02
Minke whale.....................................................           0.114           4.151           0.041           0.030           0.041           0.020           \4\ 4            0.19
Long-finned pilot whale \7\; Short-finned pilot whale \7\.......           0.029           1.038           0.010           0.007           0.010           0.005          \6\ 12            0.06
Bottlenose dolphin (Offshore)...................................           18.53     \2\ 504.234           50.93       \2\ 3.719          50.932       \2\ 2.452             511            0.81
Bottlenose dolphin (Southern Migratory Coastal).................           18.53     \2\ 168.078           50.93      \2\ 33.470          50.932      \2\ 22.068             224             6.5
Common dolphin..................................................            1.84          66.797           0.613           0.447           0.613           0.295              68            0.08
Atlantic white-sided dolphin....................................            1.18          42.992           0.386           0.282           0.386           0.186              44            0.12
Spotted dolphin.................................................           0.729          26.425           0.219           0.160           0.219           0.106              27            0.05
Risso's dolphin.................................................           0.017           0.605           0.004           0.003           0.004           0.002            6\6\            0.08
Harbor porpoise.................................................           1.059          38.396           0.375           0.274           0.375           0.181              39            0.09
Harbor seal \3\; Gray Seal \3\..................................           0.916          33.210           0.806           0.588           0.806           0.388              35            0.02
                                                                                                                                                                                            0.06
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
\1\ Cetacean density values from Duke University (Roberts et al. 2016, 2017, 2018).
\2\ Density model for bottlenose dolphins (Roberts et al. 2016, 2017, 2018) does not differentiate between offshore and coastal stocks. Take estimates split based on bottlenose dolphin stock
  preferred water depths (Reeves et al. 2002; Hayes et al. 2018).
\3\ Pinniped density values reported as ``seals'' and not species-specific.
\4\ Take adjusted to 0 given mitigation to prevent take.
\5\ Calculations of percentage of stock taken are based on the best available abundance estimate as shown in Table 2. In most cases the best available abundance estimate is provided by Roberts
  et al. (2016, 2017, 2018), when available, to maintain consistency with density estimates derived from Roberts et al. (2016, 2017, 2018). For North Atlantic right whales the best available
  abundance estimate is derived from the North Atlantic Right Whale Consortium 2019 Annual Report Card (Pettis et al. 2019). For bottlenose dolphins, Roberts et al. (2016, 2017, 2018) provides
  only a single abundance estimate and does not provide abundance estimates at the stock or species level (respectively), so abundance estimates used to estimate percentage of stock taken for
  bottlenose dolphins are derived from NMFS SARs (Hayes et al. 2019).
\6\ The number of authorized takes (Level B harassment only) for these species has been increased from the estimated take number to mean group size. Sources for mean group size estimates are
  as follows: Risso's dolphin, pilot whales (NOAA Fisheries Northeast and Southeast Fisheries Science Centers, 2019, 2018, 2017, 2016, 2015, 2014, 2013, 2012, 2011).
\7\ Density values reported as a guild for pilot whales at the genus level.

    Take authorization is not proposed for six marine mammal species 
for which potential takes by Level B harassment were estimated based on 
the modeling approach described above: North Atlantic right, humpback, 
fin, sei, sperm, and minke whale. Though the modeling resulted in 
estimates of take for these species as shown in Table 9, take of these 
species are expected to be avoided due to mitigation.
    Note that the number of proposed takes (Level B harassment only) 
for Risso's dolphin and pilot whales has been increased from the 
estimated take number to mean group size. (NOAA Fisheries Northeast and 
Southeast Fisheries Science Centers, 2019, 2018, 2017, 2016, 2015, 
2014, 2013, 2012, 2011).
    For bottlenose dolphin densities, Roberts et al. (2016, 2017, and 
2018) does not differentiate by individual stock. Given the southern 
coastal migratory stock propensity to be found shallower than the 25-m 
(82-ft) depth isobath north of Cape Hatteras (Reeves et al. 2002; Hayes 
et al. 2018) and only during the summer, the export cable corridor 
segment was roughly divided along the 25-m (82-ft) depth isobath. 
Roughly 90 percent of the cable corridor is 25 m (82 ft) or less in 
depth. The Lease Area is mostly located within depths exceeding 25 m 
(82 ft), where the southern coastal migratory stock would be unlikely. 
Roughly 25 percent of the Lease Area survey segment is 25 m (82 ft) or 
less in depth. Therefore, to account for the potential for mixed stocks 
within the export cable corridor, 90 percent of the estimated take 
calculation is applied to the southern coastal migratory stock and the 
remaining applied to the offshore migratory stock within the export 
cable corridor survey area. Within the Lease Area, 25 percent of the 
estimated take

[[Page 36557]]

calculation is applied to the southern coastal migratory stock and the 
remaining applied to the offshore migratory stock.
    Roberts et al. (2018) produced density models for all seals and did 
not differentiate by seal species. The take calculation methodology as 
described above resulted in an estimate of 35 total seal takes. An even 
split between harbor and gray seals (i.e., 18 harbor seal takes and 17 
gray seal takes) is proposed, based on an assumption that the 
likelihood of take of either species is equal.
    In the instance of the North Atlantic right whale, Dominion 
proposed a 500-m (1,640-ft) exclusion zone that exceeds the distance to 
the Level B harassment isopleth. Given that the proposed mitigation 
effectively prevents Level B harassment, take has been adjusted to zero 
individuals. In addition, Dominion proposed a 100-m (328-ft) exclusion 
zone to be implemented for all non-delphinid large cetaceans, which is 
expected to preclude potential interactions with humpback, fin, sei, 
sperm, and minke whales. Therefore, the low calculated take estimates 
for these whales was adjusted to zero individuals for these species and 
NMFS is not proposing to authorize take of these whale species.

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned), and;
    (2) the practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    Marine mammal exclusion zones (EZ) would be established around the 
HRG survey equipment and monitored by protected species observers (PSO) 
during HRG surveys as follows:
     500-m EZ would be required for North Atlantic right 
whales;
     100-m EZ would be required for large whale species;
     25-m (82-ft) EZ when only the Triple Plate Boomer 1000J is 
in use; and
     200-m (656-ft) buffer zone for all marine mammals except 
those species otherwise excluded (i.e., right whale).
    If a marine mammal is detected approaching or entering the EZs 
during the proposed survey, the vessel operator would adhere to the 
shutdown procedures described below. In addition to the EZs described 
above, PSOs would visually monitor a 200-m buffer zone. During use of 
acoustic sources with the potential to result in marine mammal 
harassment (i.e., anytime the acoustic source is active, including 
ramp-up), occurrences of marine mammals within the monitoring zone (but 
outside the EZs) would be communicated to the vessel operator to 
prepare for potential shutdown of the acoustic source. The buffer zone 
is not applicable when the EZ is greater than 100 meters. PSOs would 
also be required to observe a 500-m monitoring zone and record the 
presence of all marine mammals within this zone. The zones described 
above would be based upon the radial distance from the active equipment 
(rather than being based on distance from the vessel itself).

Visual Monitoring

    NMFS only requires a single PSO to be on duty during daylight 
hours. Dominion will have one PSO on duty during the day and has 
voluntarily proposed that a minimum of two NMFS-approved PSOs must be 
on duty and conducting visual observations when HRG equipment is in use 
at night. Visual monitoring would begin no less than 30 minutes prior 
to ramp-up of HRG equipment and would continue until 30 minutes after 
use of the acoustic source. PSOs would establish and monitor the 
applicable EZs, Buffer Zone and Monitoring Zone as described above. 
Visual PSOs would coordinate to ensure 360[deg] visual coverage around 
the vessel from the most appropriate observation posts, and would 
conduct visual observations using binoculars and the naked eye while 
free from distractions and in a consistent, systematic, and diligent 
manner. PSOs would estimate distances to observed marine mammals. It 
would be the responsibility of the Lead PSO on duty to communicate the 
presence of marine mammals as well as to communicate action(s) that are 
necessary to ensure mitigation and monitoring requirements are 
implemented as appropriate. Position data would be recorded using hand-
held or vessel global positioning system (GPS) units for each confirmed 
marine mammal sighting.

Pre-Clearance of the Exclusion Zones

    Prior to initiating HRG survey activities, Dominion would implement 
a 30-minute pre-clearance period. During pre-clearance monitoring 
(i.e., before ramp-up of HRG equipment begins), the Buffer Zone would 
also act as an extension of the 100-m EZ in that observations of marine 
mammals within the 200-m Buffer Zone would also preclude HRG operations 
from beginning. During this period, PSOs would ensure that no marine 
mammals are observed within 200 m of the survey equipment (500 m in the 
case of North Atlantic right whales). HRG equipment would not start up 
until this 200-m zone (or, 500-m zone in the case of North Atlantic 
right whales) is clear of marine mammals for at least 30 minutes. The 
vessel operator would notify a designated PSO of the proposed start of 
HRG survey equipment as agreed upon with the lead PSO; the notification 
time should not be less than 30 minutes prior to the planned initiation 
of HRG equipment order to allow the PSOs time to monitor the EZs and 
Buffer Zone for the 30 minutes of pre-clearance. A PSO conducting pre-
clearance observations would be notified again immediately prior to 
initiating active HRG sources.
    If a marine mammal were observed within the relevant EZs or Buffer 
Zone during the pre-clearance period, initiation of HRG survey 
equipment would not begin until the animal(s) has been observed exiting 
the respective EZ

[[Page 36558]]

or Buffer Zone, or, until an additional time period has elapsed with no 
further sighting (i.e., minimum 15 minutes for small odontocetes and 
seals, and 30 minutes for all other species). The pre-clearance 
requirement would include small delphinoids. PSOs would also continue 
to monitor the zone for 30 minutes after survey equipment is shut down 
or survey activity has concluded.

Ramp-Up of Survey Equipment

    When technically feasible, a ramp-up procedure would be used for 
geophysical survey equipment capable of adjusting energy levels at the 
start or re-start of survey activities. The ramp-up procedure would be 
used at the beginning of HRG survey activities in order to provide 
additional protection to marine mammals near the Survey Area by 
allowing them to detect the presence of the survey and vacate the area 
prior to the commencement of survey equipment operation at full power. 
Ramp-up of the survey equipment would not begin until the relevant EZs 
and Buffer Zone has been cleared by the PSOs, as described above. HRG 
equipment would be initiated at their lowest power output and would be 
incrementally increased to full power. If any marine mammals are 
detected within the EZs or Buffer Zone prior to or during ramp-up, the 
HRG equipment would be shut down (as described below).

Shutdown Procedures

    If an HRG source is active and a marine mammal is observed within 
or entering a relevant EZ (as described above) an immediate shutdown of 
the HRG survey equipment would be required. When shutdown is called for 
by a PSO, the acoustic source would be immediately deactivated and any 
dispute resolved only following deactivation. Any PSO on duty would 
have the authority to delay the start of survey operations or to call 
for shutdown of the acoustic source if a marine mammal is detected 
within the applicable EZ. The vessel operator would establish and 
maintain clear lines of communication directly between PSOs on duty and 
crew controlling the HRG source(s) to ensure that shutdown commands are 
conveyed swiftly while allowing PSOs to maintain watch. Subsequent 
restart of the HRG equipment would only occur after the marine mammal 
has either been observed exiting the relevant EZ, or, until an 
additional time period has elapsed with no further sighting of the 
animal within the relevant EZ (i.e., 15 minutes for small odontocetes 
and seals, and 30 minutes for large whales).
    Upon implementation of shutdown, the HRG source may be reactivated 
after the marine mammal that triggered the shutdown has been observed 
exiting the applicable EZ (i.e., the animal is not required to fully 
exit the Buffer Zone where applicable) or, following a clearance period 
of 15 minutes for small odontocetes and seals and 30 minutes for all 
other species with no further observation of the marine mammal(s) 
within the relevant EZ. If the HRG equipment shuts down for brief 
periods (i.e., less than 30 minutes) for reasons other than mitigation 
(e.g., mechanical or electronic failure) the equipment may be re-
activated as soon as is practicable at full operational level, without 
30 minutes of pre-clearance, only if PSOs have maintained constant 
visual observation during the shutdown and no visual detections of 
marine mammals occurred within the applicable EZs and Buffer Zone 
during that time. For a shutdown of 30 minutes or longer, or if visual 
observation was not continued diligently during the pause, pre-
clearance observation is required, as described above.
    The shutdown requirement would be waived for certain genera of 
small delphinids (i.e., Delphinus, Lagenorhynchus, Stenella, or 
Tursiops) under certain circumstances. If a delphinid(s) from these 
genera is visually detected within the exclusion zone shutdown would 
not be required. If there is uncertainty regarding identification of a 
marine mammal species (i.e., whether the observed marine mammal(s) 
belongs to one of the delphinid genera for which shutdown is waived), 
PSOs would use best professional judgment in making the decision to 
call for a shutdown.
    If a species for which authorization has not been granted, or, a 
species for which authorization has been granted but the authorized 
number of takes have been met, approaches or is observed within the 
area encompassing the Level B harassment isopleth (100 m or 25 m), 
shutdown would occur.

Vessel Strike Avoidance

    Vessel strike avoidance measures would include, but would not be 
limited to, the following, except under circumstances when complying 
with these requirements would put the safety of the vessel or crew at 
risk:
     Vessel operators and crews must maintain a vigilant watch 
for all protected species and slow down, stop their vessel, or alter 
course, as appropriate and regardless of vessel size, to avoid striking 
any protected species. A visual observer aboard the vessel must monitor 
a vessel strike avoidance zone around the vessel (distances stated 
below). Visual observers monitoring the vessel strike avoidance zone 
may be third-party observers (i.e., PSOs) or crew members, but crew 
members responsible for these duties must be provided sufficient 
training to (1) distinguish protected species from other phenomena and 
(2) broadly to identify a marine mammal as a right whale, other whale 
(defined in this context as sperm whales or baleen whales other than 
right whales), or other marine mammal.
     All vessels, regardless of size, must observe a 10-knot 
speed restriction in specific areas designated by NMFS for the 
protection of North Atlantic right whales from vessel strikes: any 
dynamic management areas (DMAs) when in effect, the Norfolk Seasonal 
Management Area (SMA) (from November 1 through April 30). See 
www.fisheries.noaa.gov/national/endangered-species-conservation/reducing-ship-strikes-north-atlantic-right-whales for specific detail 
regarding these areas.
     Vessel speeds must also be reduced to 10 knots or less 
when mother/calf pairs, pods, or large assemblages of cetaceans are 
observed near a vessel.
     All vessels must maintain a minimum separation distance of 
500 m from right whales. If a whale is observed but cannot be confirmed 
as a species other than a right whale, the vessel operator must assume 
that it is a right whale and take appropriate action.
     All vessels must maintain a minimum separation distance of 
100 m from sperm whales and all other baleen whales.
     All vessels must, to the maximum extent practicable, 
attempt to maintain a minimum separation distance of 50 m from all 
other protected species, with an understanding that at times this may 
not be possible (e.g., for animals that approach the vessel).
     When protected species are sighted while a vessel is 
underway, the vessel shall take action as necessary to avoid violating 
the relevant separation distance (e.g., attempt to remain parallel to 
the animal's course, avoid excessive speed or abrupt changes in 
direction until the animal has left the area). If protected species are 
sighted within the relevant separation distance, the vessel must reduce 
speed and shift the engine to neutral, not engaging the engines until 
animals are clear of the area. This does not apply to any vessel towing 
gear or any vessel that is navigationally constrained.
     These requirements do not apply in any case where 
compliance would create an imminent and serious threat to

[[Page 36559]]

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.
    Project-specific training will be conducted for all vessel crew 
prior to the start of survey activities. Confirmation of the training 
and understanding of the requirements will be documented on a training 
course log sheet. Signing the log sheet will certify that the crew 
members understand and will comply with the necessary requirements 
throughout the survey activities.

Seasonal Operating Requirements

    Dominion will conduct HRG survey activities in the vicinity of the 
right whale Mid-Atlantic seasonal management area (SMA) near Norfolk 
and the mouth of the Chesapeake Bay. Activities conducted prior to May 
1 will need to comply with the seasonal mandatory speed restriction 
period for this SMA (November 1 through April 30) for any survey work 
or transit within this area.
    Throughout all phases of the survey activities, Dominion will 
monitor NOAA Fisheries North Atlantic right whale reporting systems for 
the establishment of a dynamic management area (DMA). If NOAA Fisheries 
should establish a DMA in the Lease Area or cable route corridor being 
surveyed, within 24 hours of the establishment of the DMA Dominion will 
work with NOAA Fisheries to shut down and/or alter activities to avoid 
the DMA.
    Based on our evaluation of the applicant's proposed measures, NMFS 
has preliminarily determined that the proposed mitigation measures 
provide the means effecting the least practicable impact on the 
affected species or stocks and their habitat, paying particular 
attention to rookeries, mating grounds, and areas of similar 
significance.

Proposed Monitoring and Reporting

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

Proposed Monitoring Measures

    As described above, visual monitoring would be performed by 
qualified and NMFS-approved PSOs. Dominion would use independent, 
dedicated, trained PSOs, meaning that the PSOs must be employed by a 
third-party observer provider, must have no tasks other than to conduct 
observational effort, collect data, and communicate with and instruct 
relevant vessel crew with regard to the presence of marine mammals and 
mitigation requirements (including brief alerts regarding maritime 
hazards), and must have successfully completed an approved PSO training 
course appropriate for their designated task. Dominion would provide 
resumes of all proposed PSOs (including alternates) to NMFS for review 
and approval prior to the start of survey operations.
    During survey operations (e.g., any day on which use of an HRG 
source is planned to occur), a single PSO must be on duty and 
conducting visual observations during the day on all active survey 
vessels when HRG equipment is operating. Additionally, Dominion has 
stated their intention to deploy two PSOs on duty during night 
operations. Visual monitoring would begin no less than 30 minutes prior 
to initiation of HRG survey equipment and would continue until one hour 
after use of the acoustic source ceases. PSOs would coordinate to 
ensure 360[deg] visual coverage around the vessel from the most 
appropriate observation posts, and would conduct visual observations 
using binoculars and the naked eye while free from distractions and in 
a consistent, systematic, and diligent manner. PSOs may be on watch for 
a maximum of four consecutive hours followed by a break of at least two 
hours between watches and may conduct a maximum of 12 hours of 
observation per 24-hour period. In cases where multiple vessels are 
surveying concurrently, any observations of marine mammals would be 
communicated to PSOs on all survey vessels.
    PSOs would be equipped with binoculars and have the ability to 
estimate distances to marine mammals located in proximity to the vessel 
and/or exclusion zone. Reticulated binoculars will be available to PSOs 
for use as appropriate based on conditions and visibility to support 
the monitoring of marine mammals. Position data would be recorded using 
hand-held or vessel GPS units for each sighting. Observations would 
take place from the highest available vantage point on the survey 
vessel. General 360-degree scanning would occur during the monitoring 
periods, and target scanning by the PSO would occur when alerted of a 
marine mammal presence.
    During good conditions (e.g., daylight hours; Beaufort sea state 
(BSS) 3 or less), to the maximum extent practicable, PSOs would 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. Any observations of marine 
mammals by crew members aboard any vessel associated with the survey 
would be relayed to the PSO team.
    Data on all PSO observations would be recorded based on standard 
PSO collection requirements. This would include dates, times, and 
locations of survey operations; dates and times of observations, 
location and weather; details of marine mammal sightings (e.g., 
species, numbers, behavior); and details of any observed marine mammal 
take that occurs (e.g., noted behavioral disturbances).

[[Page 36560]]

Proposed Reporting Measures

    Within 90 days after completion of survey activities, a final 
technical report will be provided to NMFS that fully documents the 
methods and monitoring protocols, summarizes the data recorded during 
monitoring, summarizes the number of marine mammals observed during 
survey activities (by species, when known), summarizes the mitigation 
actions taken during surveys (including what type of mitigation and the 
species and number of animals that prompted the mitigation action, when 
known), and provides an interpretation of the results and effectiveness 
of all mitigation and monitoring. Any recommendations made by NMFS must 
be addressed in the final report prior to acceptance by NMFS.
    In the event that Dominion personnel discover an injured or dead 
marine mammal, Dominion shall report the incident to the Office of 
Protected Resources (OPR), NMFS and to the New England/Mid-Atlantic 
Regional Stranding Coordinator as soon as feasible. The report must 
include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.
    In the event of a ship strike of a marine mammal by any vessel 
involved in the activities covered by the authorization, the IHA-holder 
shall report the incident to OPR, NMFS and to the New England/Mid-
Atlantic Regional Stranding Coordinator as soon as feasible. The report 
must include the following information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Species identification (if known) or description of the 
animal(s) involved;
     Vessel's speed during and leading up to the incident;
     Vessel's course/heading and what operations were being 
conducted (if applicable);
     Status of all sound sources in use;
     Description of avoidance measures/requirements that were 
in place at the time of the strike and what additional measures were 
taken, if any, to avoid strike;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
     Estimated size and length of animal that was struck;
     Description of the behavior of the marine mammal 
immediately preceding and following the strike;
     If available, description of the presence and behavior of 
any other marine mammals immediately preceding the strike;
     Estimated fate of the animal (e.g., dead, injured but 
alive, injured and moving, blood or tissue observed in the water, 
status unknown, disappeared); and
     To the extent practicable, photographs or video footage of 
the animal(s).

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 9, given that NMFS expects the anticipated effects of the 
proposed survey to be similar in nature. As discussed in the Potential 
Effects of the Specified Activities on Marine Mammals and Their Habitat 
section, PTS, masking, non-auditory physical effects, and vessel strike 
are not expected to occur.
    The majority of impacts to marine mammals are expected to be short-
term disruption of behavioral patterns, primarily in the form of 
avoidance or potential interruption of foraging. Marine mammal feeding 
behavior is not likely to be significantly impacted.
    Regarding impacts to marine mammal habitat, prey species are 
mobile, and are broadly distributed throughout the Survey Area and the 
footprint of the activity is small; 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 availability of 
similar habitat and resources in the surrounding area the impacts to 
marine mammals and the food sources that they utilize are not expected 
to cause significant or long-term consequences for individual marine 
mammals or their populations. The HRG survey equipment itself will not 
result in physical habitat disturbance. Avoidance of the area around 
the HRG survey activities by marine mammal prey species is possible. 
However, any avoidance by prey species would be expected to be short 
term and temporary.
    The status of the North Atlantic right whale population is of 
heightened concern and, therefore, merits additional analysis. The 
proposed Survey Area includes a biologically important migratory area 
for North Atlantic right whales (effective March-April and November-
December) that extends from Massachusetts to Florida (LaBrecque, et al. 
2015). As previously noted, no take of North Atlantic right whales has 
been proposed for authorization, and HRG survey operations will be 
required to shut down at 500 m to further minimize any potential 
effects to this species. This is highly precautionary considering the 
Level B harassment isopleth for the largest source utilized (i.e. Geo 
Marine Dual 400 Sparker 800J is estimated to be 100 m). The fact that 
the spatial acoustic footprint of the proposed survey is very small 
relative to the spatial extent of the available migratory habitat leads 
us to expect that right whale migration will not be impacted by the 
proposed survey. Additionally, a UME for right whales was declared in 
June 2017, primarily due to mortality events in the Gulf of St. 
Lawrence region of Canada and around

[[Page 36561]]

the Cape Cod area of Massachusetts. Overall, preliminary findings 
support human interactions, specifically vessel strikes or rope 
entanglements, as the cause of death for the majority of the right 
whales. Furthermore, these locations are found far to the north of the 
proposed Survey Area.
    No take has been proposed for authorization for ESA-listed species 
including right, fin, sei, and sperm whales and NMFS does not 
anticipate that serious injury or mortality would occur to any species, 
even in the absence of mitigation. The planned survey is not 
anticipated to affect the fitness or reproductive success of individual 
animals. Since impacts to individual survivorship and fecundity are 
unlikely, the planned survey is not expected to result in population-
level effects for any ESA-listed species or alter current population 
trends of any ESA-listed species.
    As noted previously, elevated humpback whale mortalities have 
occurred along the Atlantic coast from Maine through Florida since 
January 2016. Of the cases examined, approximately half had evidence of 
human interaction (ship strike or entanglement). The UME does not yet 
provide cause for concern regarding population-level impacts. Despite 
the UME, the relevant population of humpback whales (the West Indies 
breeding population, or distinct population segment (DPS)) remains 
healthy.
    Beginning in January 2017, elevated minke whale strandings have 
occurred along the Atlantic coast from Maine through South Carolina, 
with highest numbers in Massachusetts, Maine, and New York. This event 
does not provide cause for concern regarding population level impacts, 
as the likely population abundance is greater than 20,000 whales. 
Additionally, elevated numbers of harbor seal and gray seal mortalities 
were first observed in July 2018 and have occurred across Maine, New 
Hampshire and Massachusetts. Based on tests conducted so far, the main 
pathogen found in the seals is phocine distemper virus although 
additional testing to identify other factors that may be involved in 
this UME are underway. The UME does not yet provide cause for concern 
regarding population-level impacts to any of these stocks. For harbor 
seals, the population abundance is over 75,000 and annual M/SI (350) is 
well below PBR (2,006) (Hayes et al. 2018). The population abundance of 
gray seals in the United States is in excess of 27,000 and likely 
increasing (Wood et al. 2019). The estimated abundance increases to 
505,000 when seals from Canada are included. Given that any Level B 
harassment of gray and harbor seals will be minor, short term, and 
temporary the proposed authorized takes of gray and harbor seals would 
not exacerbate or compound the ongoing UMEs in any way.
    Direct physical interactions (ship strikes and entanglements) 
appear to be responsible for many of the UME humpback and right whale 
mortalities recorded. The proposed HRG survey will require ship strike 
avoidance measures which would minimize the risk of ship strikes while 
fishing gear and in-water lines will not be employed as part of the 
survey. Furthermore, the proposed activities are not expected to 
promote the transmission of infectious disease among marine mammals. 
The survey is not expected to result in the deaths of any marine 
mammals or combine with the effects of the ongoing UMEs to result in 
any additional impacts not analyzed here. NMFS is not proposing to 
authorize take of large whales and is not proposing to authorize take 
of any marine mammal species by serious injury, or mortality.
    The required mitigation measures are expected to reduce the number 
and/or severity of takes by giving animals the opportunity to move away 
from the sound source before HRG survey equipment reaches full energy 
and preventing animals from being exposed to sound levels that have the 
potential to result in more severe Level B harassment during HRG survey 
activities. Due to the small size of PTS zones no Level A harassment is 
anticipated or proposed for authorization.
    NMFS expects that most takes would primarily be in the form of 
short-term Level B behavioral harassment in the form of brief startling 
reaction and/or temporary vacating of the area, or decreased foraging 
(if such activity were occurring)--reactions that (at the scale and 
intensity anticipated here) are considered to be of low severity and 
with no lasting biological consequences. Since both the source and the 
marine mammals are mobile, only a smaller area would be ensonified by 
sound levels that could result in take for only a short period.
    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;
     No Level A harassment (PTS) is anticipated;
     Any foraging interruptions are expected to be short term 
and unlikely to be cause significantly impacts;
     Impacts on marine mammal habitat and species that serve as 
prey species for marine mammals are expected to be minimal and the 
alternate areas of similar habitat value for marine mammals are readily 
available;
     Take is anticipated to be by Level B behavioral harassment 
only consisting of brief startling reactions and/or temporary avoidance 
of the Survey Area;
     Survey activities would occur in such a comparatively 
small portion of the biologically important areas for north Atlantic 
right whale migration, that any avoidance of the Survey Area due to 
activities would not affect migration. In addition, mitigation measures 
to shut down at 500 m to minimize potential for Level B behavioral 
harassment would limit both the number and severity of take of the 
species; and
     Proposed mitigation measures, including visual monitoring 
and shutdowns, are expected to minimize the intensity of 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 Sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one third of the species or stock 
abundance, the take is considered to be of small numbers. For this IHA, 
take of all species or stocks is below one third of the estimated stock 
abundance (in fact, take of individuals is less than 7 percent of the 
abundance for all affected stocks). Additionally, other qualitative 
factors may be considered in the analysis, such as the

[[Page 36562]]

temporal or spatial scale of the activities.
    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 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

Endangered Species Act (ESA)

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA: 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS consults internally whenever we propose to authorize take or 
propose mitigation measures that would avoid incidental take of 
endangered or threatened species, in this case with the Greater 
Atlantic Regional Field Office (GARFO). In the absence of proposed 
mitigation measures take of North Atlantic right whale, fin whale, sei 
whale, and sperm whale could potentially occur.
    The Permits and Conservation Division has requested initiation of 
Section 7 consultation with GARFO for the issuance of this IHA. NMFS 
will conclude the ESA consultation prior to reaching a determination 
regarding the proposed issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to Dominion for conducting HRG surveys off the coast of 
Virginia for a period of one year after the issuance of the IHA, 
provided the previously mentioned mitigation, monitoring, and reporting 
requirements are incorporated. A draft of the proposed IHA can be found 
at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this Notice of Proposed IHA for the proposed HRG 
surveys. We also request at this time comment on the potential Renewal 
of this proposed IHA as described in the paragraph below. Please 
include with your comments any supporting data or literature citations 
to help inform decisions on the request for this IHA or a subsequent 
Renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time one-year Renewal 
IHA following notice to the public providing an additional 15 days for 
public comments when (1) up to another year of identical or nearly 
identical, or nearly identical, activities as described in the 
Specified Activities section of this notice is planned or (2) the 
activities as described in the Specified Activities section of this 
notice would not be completed by the time the IHA expires and a Renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed Renewal IHA effective date (recognizing that the 
Renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA).
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested Renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take); 
and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized;
     Upon review of the request for Renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: June 11, 2020.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2020-12997 Filed 6-16-20; 8:45 am]
BILLING CODE 3510-22-P