[Federal Register Volume 86, Number 35 (Wednesday, February 24, 2021)]
[Notices]
[Pages 11239-11266]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-03821]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XA852]


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

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 Skipjack Offshore Energy, LLC 
(Skipjack) for authorization to take marine mammals incidental to 
marine site characterization surveys offshore of Delaware in the area 
of the Commercial Lease of Submerged Lands for Renewable Energy 
Development on the Outer Continental Shelf (OCS-A 0519) and along 
potential submarine cable routes to a landfall location in Delaware. 
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 March 
26, 2021.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Written comments should be submitted 
via email to <a href="/cdn-cgi/l/email-protection#034a57532d5362766f6a6d66436d6c62622d646c75"><span class="__cf_email__" data-cfemail="115845413f4170647d787f74517f7e70703f767e67">[email protected]</span></a>.
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments, including all attachments, must 
not exceed a 25-megabyte file size. All comments received are a part of 
the public record and will generally be posted online at 
www.fisheries.noaa.gov/permit/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

[[Page 11240]]

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 NMFS 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.
    NMFS 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 August 12, 2020, NMFS received a request from Skipjack for an 
IHA to take marine mammals incidental to marine site characterization 
surveys offshore of Delaware in the area of the Commercial Lease of 
Submerged Lands for Renewable Energy Development on the Outer 
Continental Shelf (OCS-A 0519) and along potential submarine cable 
routes to a landfall location in Delaware. Revised versions of the 
application were received on September 21, 2020 and November 5, 2020. 
The application was deemed adequate and complete on December 12, 2020. 
Skipjack's request is for take of a small number of 16 species of 
marine mammals by Level B harassment only. Neither Skipjack nor NMFS 
expects serious injury or mortality to result from this activity and, 
therefore, an IHA is appropriate.
    NMFS previously issued an IHA to Skipjack for similar work in the 
same geographic area on December 3, 2019 (84 FR 66156) with effectives 
dates from November 26, 2019 through November 25, 2020. Skipjack 
complied with all the requirements (e.g., mitigation, monitoring, and 
reporting) of the previous IHA and given the similarity in activities 
and location, relevant information regarding their previous marine 
mammal monitoring results may be found in the Estimated Take section.

Description of Proposed Activity

Overview

    As part of its overall marine site characterization survey 
operations, Skipjack proposes to conduct high-resolution geophysical 
(HRG) surveys, in the area of Commercial Lease of Submerged Lands for 
Renewable Energy Development on the Outer Continental Shelf #OCS-A 0519 
(Lease Area) and along potential submarine cable routes to landfall 
locations in Delaware.
    The purpose of the marine site characterization surveys are to 
obtain a baseline assessment of seabed (geophysical, geotechnical, and 
geohazard), ecological, and archeological conditions within the 
footprint of offshore wind facility development. Surveys are also 
conducted to support engineering design and to map Unexploded 
Ordinances (UXO survey). Underwater sound resulting from Skipjack's 
proposed site characterization survey activities, specifically HRG 
surveys have the potential to result in incidental take of marine 
mammals in the form of behavioral harassment.

Dates and Duration

    The estimated duration of HRG survey activity is expected to be up 
to 200 survey days over the course of a single year. Skipjack proposes 
to start survey activity in April 2021. The IHA would be effective for 
one year from the date of issuance. This schedule is based on 24-hour 
operations and includes potential down time due to inclement weather.

Specific Geographic Region

    The proposed survey activities will occur within the Project Area 
which includes the Lease Area and along potential submarine cable 
routes to landfall locations in the state of Delaware, as shown in 
Figure 1. The Lease Area is approximately 284 square kilometers (km\2\) 
and is within the Delaware Wind Energy Area (WEA) of the Bureau of 
Ocean Energy Management (BOEM) Mid-Atlantic planning area. Water depths 
in the Lease Area range from 15 meters (m) to 40 m. Water depths in the 
submarine cable area extend from the shoreline to approximately 40 m.
BILLING CODE 3510-22-P

[[Page 11241]]

[GRAPHIC] [TIFF OMITTED] TN24FE21.006

BILLING CODE 3510-22-C

Detailed Description of Specific Activity

    Skipjack has proposed that survey operations, including HRG survey 
activities operations would be conducted continuously 24 hours per day. 
Based on 24-hour operations, the estimated duration of the HRG survey 
activities would be approximately 200 days (including estimated weather 
down time). As many as four vessels may be engaged in HRG surveying 
activities during Skipjack's overall site characterization efforts with 
up to two working concurrently in the Lease Area or along the submarine 
cable route (e.g., two vessels in the Lease Area; one vessel in the 
general area and one vessel on the portion of the submarine cable route 
within the area; two vessels on the submarine cable route outside of 
the

[[Page 11242]]

area). Vessels working in shallow or very shallow waters would only 
operate during daylight hours. Vessels would be at least one kilometer 
(km) apart at all times. Vessels would maintain a speed of 
approximately 4 knots (kn) while transiting survey lines and cover 
approximately 70 km per day. The daily distance surveyed could be more 
or less than this based on weather and other factors, but an average of 
70 km per day is assumed in estimating the total number of survey days 
and in estimating the daily ensonified area (see Estimated Take). 
Impulsive sources (e.g., sparker systems) would be utilized for 50 
survey days while the non-impulsive sources (e.g., sub-bottom profilers 
(SBPs)) would be used for the remaining 150 days. See following 
discussion and Table 1. The survey activities proposed by Skipjack with 
acoustic source types that could result in take of marine mammals 
include the following:
    <bullet> Shallow penetration, non-impulsive, non-parametric sub-
bottom profilers (SBPs, also known as CHIRPs) are used to map the near-
surface stratigraphy (top 0 to 10 m) of sediment below seabed. A CHIRP 
system emits signals covering a frequency sweep from approximately 2 to 
20 kHz over time. The frequency range can be adjusted to meet project 
variables.
    <bullet> Medium penetration, impulsive sources (boomers, sparkers) 
are used to map deeper subsurface stratigraphy as needed. A boomer is a 
broad-band sound source operating in the 3.5 Hz to 10 kHz frequency 
range. Sparkers are used to map deeper subsurface stratigraphy as 
needed. Sparkers create acoustic pulses from 50 Hz to 4 kHz omni-
directionally from the source.
    Operation of the following survey equipment types is not reasonably 
expected to result in take of marine mammals and will not be carried 
forward in the application analysis beyond the brief summaries provided 
below.
    <bullet> Non-impulsive, parametric SBPs are used for providing high 
data density in sub-bottom profiles that are typically required for 
cable routes, very shallow water, and archaeological surveys. The 
narrow beamwidth (1[deg] to 3.5[deg]) significantly reduces the impact 
range of the source while the high frequencies of the source are 
rapidly attenuated in sea water. Because of the high frequency of the 
source and narrow bandwidth, parametric SBPs do not produce Level B 
harassment isopleths beyond 4 m. No Level B harassment exposures can be 
reasonably expected from the operation of these sources.
    <bullet> Acoustic corers, unlike the other mobile geophysical 
sources, are stationary and made up of three distinct sound sources 
comprised of a HF parametric sonar (which will not be included in this 
assessment), a HF CHIRP sonar, and a LF CHIRP sonar with each source 
having its own transducer. The corer is seabed-mounted; therefore, 
propagation for similar towed equipment is unlikely to be fully 
comparable. The beam width of the parametric sonar is narrow (3.5[deg] 
to 8[deg]) and the sonar is operated roughly 3.5 m above the seabed 
with the transducer pointed directly downward. No take is expected to 
result from use of these highly directional, seabed-mounted sources.
    <bullet> Ultra-short baseline (USBL) positioning systems are used 
to provide high accuracy ranges by measuring the time between the 
acoustic pulses transmitted by the vessel transceiver and a transponder 
(or beacon) necessary to produce the acoustic profile. USBLs have been 
shown to produce extremely small acoustic propagation distances in 
their typical operating configuration. Based on this information, no 
Level B harassment exposures can be reasonably expected from the 
operation of these sources.
    <bullet> Multibeam echosounders (MBESs) are used to determine water 
depths and general bottom topography. The proposed MBESs all have 
operating frequencies >180 kHz, they are outside the general hearing 
range of marine mammals likely to occur in the Project Area and are not 
likely to affect these species.
    <bullet> Side scan sonars (SSS) are used for seabed sediment 
classification purposes and to identify natural and man-made acoustic 
targets on the seafloor. The proposed SSSs all have operating 
frequencies >180 kHz, they are outside the general hearing range of 
marine mammals likely to occur in the Project Area and are not likely 
to affect these species.
    Table 1 identifies all the representative survey equipment that 
operate below 180 kHz (i.e., at frequencies that are audible to and 
therefore may be detected by marine mammals) that may be used in 
support of planned HRG survey activities, some of which have the 
expected potential to result in exposure of marine mammals. The make 
and model of the listed geophysical equipment may vary depending on 
availability and the final equipment choices will vary depending upon 
the final survey design, vessel availability, and survey contractor 
selection.

                                                    Table 1--Summary of Representative HRG Equipment
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   SLrms  (dB  SL0-pk  (dB       Pulse
                                   Acoustic source    Operating       re 1         re 1        duration      Repetition   Beamwidth    CF = Crocker and
           Equipment                    type          frequency    [micro]Pa    [micro]Pa       (width)      rate  (Hz)   (degrees)   Fratantonio (2016)
                                                        (kHz)          m)           m)       (millisecond)                            MAN = Manufacturer
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                       Non-Impulsive, Non-Parametric, Shallow Sub-Bottom Profilers (CHIRP Sonars)
--------------------------------------------------------------------------------------------------------------------------------------------------------
ET 216 (2000DS or 3200 top       Non-impulsive,             2-16          195  ...........              20            6           24  MAN.
 unit).                           mobile,                    2-8
                                  intermittent.
ET 424.........................  Non-impulsive,             4-24          176  ...........             3.4            2           71  CF.
                                  mobile,
                                  intermittent.
ET 512.........................  Non-impulsive,           0.7-12          179  ...........               9            8           80  CF.
                                  mobile,
                                  intermittent.
GeoPulse 5430A.................  Non-impulsive,             2-17          196  ...........              50           10           55  MAN.
                                  mobile,
                                  intermittent.
Teledyne Benthos Chirp III--TTV  Non-impulsive,              2-7          197  ...........              60           15          100  MAN.
 170.                             mobile,
                                  intermittent.
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 11243]]

 
                                               Impulsive, Medium Sub-Bottom Profilers (Sparkers & Boomers)
--------------------------------------------------------------------------------------------------------------------------------------------------------
AA, Dura-spark UHD (400 tips,    Impulsive, mobile.      0.3-1.2          203          211             1.1            4         Omni  CF.
 500 J) \2\.
AA, Dura-spark UHD (400+400)     Impulsive, mobile.      0.3-1.2          203          211             1.1            4         Omni  CF (AA Dura-spark
 \2\.                                                                                                                                  UHD Proxy).
GeoMarine, Geo-Source dual 400   Impulsive, mobile.        0.4-5          203          211             1.1            2         Omni  CF (AA Dura-spark
 tip sparker (800 J) \2\.                                                                                                              UHD Proxy).
GeoMarine Geo-Source 200 tip     Impulsive, mobile.      0.3-1.2          203          211             1.1            4         Omni  CF (AA Dura-spark
 sparker (400 J) \2\.                                                                                                                  UHD Proxy).
GeoMarine Geo-Source 200-400     Impulsive, mobile.      0.3-1.2          203          211             1.1            4         Omni  CF (AA Dura-spark
 tip sparker (400 J) \2\.                                                                                                              UHD Proxy).
AA, triple plate S-Boom (700-    Impulsive, mobile.        0.1-5          205          211             0.6            4           80  CF.
 1,000 J) \3\.
--------------------------------------------------------------------------------------------------------------------------------------------------------

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

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS's Stock Assessment Reports (SARs; 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 Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. For taxonomy, NMFS follows the Committee on 
Taxonomy (2020). 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 and Gulf of Mexico SARs. All values presented in 
Table 2 are the most recent available at the time of publication and 
are available in the 2020 SARs (Hayes et al., 2020) and draft 2021 SARS 
available at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports.

                    Table 2--Marine Mammal Species Likely To Occur Near the Project Area That May be Affected by Skipjack's Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/ MMPA
                                                                                          status;        Stock abundance (CV,                 Annual  M/
            Common name                  Scientific name              Stock           Strategic  (Y/N)     Nmin, most recent        PBR         SI \3\
                                                                                            \1\          abundance survey) \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Balaenidae:
    North Atlantic right whale.....  Eubalaena glacialis...  Western North Atlantic  E/D; Y             412 (0; 408; 2018)....          0.8         18.6
Family Balaenopteridae (rorquals):
    Humpback whale.................  Megaptera novaeangliae  Gulf of Maine.........  -/-; Y             1,393 (0; 1,375; 2016)           22           58
    Fin whale......................  Balaenoptera physalus.  Western North Atlantic  E/D; Y             6,802 (0.24; 5,573;              11         2.35
                                                                                                         2016).
    Sei whale......................  Balaenoptera borealis.  Nova Scotia...........  E/D; Y             6,292 (1.015; 3,098;            6.2          1.2
                                                                                                         see SAR).
    Minke whale....................  Balaenoptera            Canadian East Coast...  -/-; N             21,968 (0.31; 17,002;           170         10.6
                                      acutorostrata.                                                     2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Physeteridae:
    Sperm whale....................  Physeter macrocephalus  NA....................  E; Y               4,349 (0.28;3,451; See          3.9            0
                                                                                                         SAR).
Family Delphinidae:
    Long-finned pilot whale........  Globicephala melas....  Western North Atlantic  -/-; N             39,215 (0.30; 30,627;           306           21
                                                                                                         See SAR).
    Short finned pilot whale.......  Globicephala            Western North Atlantic  -/-;Y              28,924 (0.24; 23,637;           236          160
                                      macrorhynchus.                                                     See SAR).

[[Page 11244]]

 
    Bottlenose dolphin.............  Tursiops truncatus....  Western North Atlantic  -/-; N             62,851 (0.23; 51,914;           519           28
                                                              Offshore.                                  See SAR).
                                                             W.N.A. Northern         -/-;Y              6,639 (0.41,4 ,759,              48    12.2-21.5
                                                              Migratory Coastal.                         2016).
    Common dolphin.................  Delphinus delphis.....  Western North Atlantic  -/-; N             172,897 (0.21;                1,452          399
                                                                                                         145,216; 2016).
    Atlantic white-sided dolphin...  Lagenorhynchus acutus.  Western North Atlantic  -/-; N             93,233 (0.71; 54,443;           544           26
                                                                                                         See SAR).
    Atlantic spotted dolphin.......  Stenella frontalis....  Western North Atlantic  -/-; N             39,921 (0.27; 32,032;           320            0
                                                                                                         2012).
    Risso's dolphin................  Grampus griseus.......  Western North Atlantic  -/-; N             35,493 (0.19; 30,289;           303         54.3
                                                                                                         See SAR).
Family Phocoenidae (porpoises):
    Harbor porpoise................  Phocoena phocoena.....  Gulf of Maine/Bay of    -/-; N             95,543 (0.31; 74,034;           851          217
                                                              Fundy.                                     See SAR).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
    Gray seal \4\..................  Halichoerus grypus....  Western North Atlantic  -/-; N             27,131 (0.19; 23,158,         1,389        5,410
                                                                                                         2016).
    Harbor seal....................  Phoca vitulina........  Western North Atlantic  -/-; N             75,834 (0.15; 66,884,         2,006          350
                                                                                                         2018).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ 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\ 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. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ The NMFS stock abundance estimate applies to U.S. population only, however the actual stock abundance is approximately 451,431.

    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, and NMFS has proposed 
authorizing it.

North Atlantic Right Whale

    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., 2020). NMFS et al. 2020 identified 
seven areas where Western North Atlantic right whale aggregate 
seasonally: The coastal waters of the southeastern United States, the 
Great South Channel, Jordan Basin, Georges Basin along the northeastern 
edge of Georges Bank, Cape Cod and Massachusetts Bays, the Bay of 
Fundy, and the Roseway Basin on the Scotian Shelf (Brown et al., 2001; 
Cole et al., 2013). Several of these congregation areas correlate with 
seasonally high copepod concentrations (Pendleton et al., 2009). New 
England waters are a primary feeding habitat for North Atlantic right 
whales during late winter through spring, with feeding moving into 
deeper and more northerly waters during summer and fall. Less is known 
regarding winter distributions; however, it is understood that calving 
takes place during this time in coastal waters of the Southeastern 
United States.
    Passive acoustic studies of North Atlantic right whales have 
demonstrated their year-round presence in the Gulf of Maine (Morano et 
al., 2012; Bort et al., 2015), New Jersey (Whitt et al., 2013), and 
Virginia (Salisbury et al., 2016). Additionally, North Atlantic right 
whales were acoustically detected off Georgia and North Carolina during 
7 of the 11 months monitored (Hodge et al., 2015). All of this work 
further demonstrates the highly mobile nature of North Atlantic right 
whales. Movements within and between habitats are extensive and the 
area off the Mid-Atlantic states is an important migratory corridor. 
While no critical habitat is listed within the Project Area, 11 North 
Atlantic right whales were identified in the Mid-Atlantic Baseline 
Studies (MABS) surveys conducted between 2012 and 2014 with a total of 
nine sightings occurring in February (n=5) and March (n=4) (Williams et 
al., 2015a, b). Davis et al. (2017) recently examined detections from 
passive acoustic monitoring devices and documented a broad-scale use of 
much more of the U.S. eastern seaboard than was previously believed, 
and an apparent shift in habitat use patterns to the south of 
traditionally identified North Atlantic right whale congregations. 
Increased use of Cape Cod Bay and decreased use of the Great South 
Channel were also observed (Davis et al., 2017).
    Off the coast of New Jersey, North Atlantic right whales were 
acoustically detected in all seasons and visually observed in winter, 
spring, and summer during an environment baseline study (EBS) conducted 
by the New Jersey Department of Environmental Protection (NJDEP, 2010). 
The greatest number of acoustic detections occurred during April and 
May (Whitt et al., 2013). Reports from the RWSAS for the Mid-Atlantic 
Region (New Jersey through Virginia) show 24 records off the coast of 
New Jersey since 2015: January (7), March (1), April (4), October (1) 
and December (11) (NOAA, 2019).
    Elevated North Atlantic right whale mortalities have occurred since 
June 7, 2017 along the U.S. and Canadian coast. As of January 2021, a 
preliminary cumulative total number of animals in the North Atlantic 
right whale UME has been updated to 46 individuals to include both the 
confirmed mortalities (dead stranded or floaters) (n=32) and seriously 
injured free-swimming whales (n=14) to better reflect the confirmed 
number of whales likely removed from the population during the UME and

[[Page 11245]]

more accurately reflect the population impacts. A total of 32 confirmed 
dead stranded whales (21 in Canada; 11 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 15 of the mortalities 
thus far. More information is available online at: 
www.fisheries.noaa.gov/national/marine-life-distress/2017-2021-north-atlantic-right-whale-unusual-mortality-event.
    The proposed survey area is part of a migratory corridor 
Biologically Important Area (BIA) for North Atlantic right whales 
(effective March-April and November-December) that extends from 
Massachusetts to Florida (LeBrecque et al., 2015). Off the coast of 
Delaware, migratory BIA extends from the coast to beyond the shelf 
break. This important migratory area is approximately 269,488 km\2\ in 
size and is comprised of the waters of the continental shelf offshore 
the East Coast of the United States and extends from Florida through 
Massachusetts. For comparative purposes, the size of the Lease Area is 
284 km\2\. 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. A portion of 
one SMA, which occurs off the mouth of Delaware Bay, overlaps spatially 
with a section of the proposed survey area. The SMA which occurs off 
the mouth of Delaware Bay is active from November 1 through April 30 of 
each year.

Humpback Whale

    Humpback whales are found worldwide in all oceans. Humpback whales 
were listed as endangered under the Endangered Species Conservation Act 
(ESCA) in June 1970. In 1973, the ESA replaced the ESCA, and humpbacks 
continued to be listed as endangered. NMFS recently evaluated the 
status of the species, and on September 8, 2016, NMFS divided the 
species into 14 distinct population segments (DPS), removed the current 
species-level listing, and in its place listed four DPSs as endangered 
and one DPS as threatened (81 FR 62259; September 8, 2016). The 
remaining nine DPSs were not listed. The West Indies DPS, which is not 
listed under the ESA, is the only DPS of humpback whale that is 
expected to occur in the Project Area.
    Humpback whales have a global distribution and follow a migratory 
pattern of feeding in the high latitudes during summers and spending 
winters in the lower latitudes for calving and mating. The Gulf of 
Maine stock follows this pattern with winters spent in the Caribbean 
and West Indies, although acoustic recordings show a small number of 
males persisting in Stellwagen Bank throughout the year (Vu et al., 
2012). Barco et al. (2002) suggested that the mid-Atlantic region 
primarily represents a supplemental winter feeding ground used by 
humpbacks. However, with populations recovering, additional surveys 
that include photo identification and genetic sampling need to be 
conducted to determine which stocks are currently using the mid-
Atlantic region.
    Sightings of humpback whales in the Mid-Atlantic are common (Barco 
et al., 2002), as are strandings (Wiley et al., 1995). Barco et al. 
(2002) suggested that the Mid-Atlantic region primarily represents a 
supplemental winter feeding ground used by humpbacks. During the MABS 
surveys, a total of 13 humpback whales were recorded between 2012 and 
2014: Eight during the winter, one during the summer, and four during 
the fall (Williams et al., 2015a, b). There was a total of 17 groups 
sighted during the NJDEP EBS, nine of which occurred during winter 
months (Whitt et al., 2015).
    Since January 2016, elevated humpback whale mortalities have 
occurred along the Atlantic coast from Maine to Florida. Partial or 
full necropsy examinations have been conducted on approximately half of 
the 145 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/2016-2021-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 (Hayes et 
al., 2020). Fin whales are present north of 35-degree latitude in every 
season and are broadly distributed throughout the western North 
Atlantic for most of the year, though densities vary seasonally (Hayes 
et al., 2020). Fin whales accounted for 46 percent of the large whales 
sighted during aerial surveys along the continental shelf (CETAP, 1982) 
between Cape Hatteras and Nova Scotia from 1978 to 1982. Fin whales 
were also the most frequently sighted large whale species during the 
New Jersey Department of Environmental Protection (NJDEP) Ecological 
Baseline Studies (EBS) with 37 groups sighted throughout all seasons 
(Whitt et al., 2015). The MABS surveys (Williams et al., 2015a, b) 
reported two fin whales during the winter and two during the spring.
    Fin whales are found in small groups of up to five individuals 
(Brueggeman et al., 1987). The main threats to fin whales are fishery 
interactions and vessel collisions (Hayes et al., 2020).

Sei Whale

    The Nova Scotia stock of sei whales can be found in deeper waters 
of the continental shelf edge waters of the northeastern United States 
and northeastward to south of Newfoundland. Two subspecies of sei 
whales are currently recognized (Committee on Taxonomy, 2018) and the 
Northern sei whale (B. b. borealis) is known to occur within the 
Project Area. Sei whales are most common in deeper waters along the 
continental shelf edge (Hayes et al., 2020) but will forage 
occasionally in shallower, inshore waters. 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 (Hayes et al., 
2020). Sei whales occur in shallower waters to feed. Sei whales are 
listed as engendered under the ESA, and the Nova Scotia stock is 
considered strategic and depleted under the MMPA. The main threats to 
this stock are interactions with fisheries and vessel collisions (Hayes 
et al., 2020).

[[Page 11246]]

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[ordm] W) to the Gulf of Mexico 
(Hayes et al., 2020). 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 (Hayes et al., 2020). 
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 103 strandings recorded through January 2021 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/2017-2021-minke-whale-unusual-mortality-event-along-atlantic-coast.

Sperm Whale

    The distribution of the sperm whale in the U.S. Exclusive Economic 
Zone (EEZ) occurs on the continental shelf edge, over the continental 
slope, and into mid-ocean regions (Hayes et al. 2020). 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 
(Hayes et al., 2020).
    No sperm whales were recorded during the MABS surveys or the NJDEP 
EBS. CETAP and NMFS Northeast Fisheries Science Center sightings in 
shelf edge and off-shelf waters included many social groups with 
calves/juveniles (CETAP, 1982). Sperm whales were usually seen at the 
tops of seamounts and rises and did not generally occur over slopes. 
Sperm whales were recorded at depths varying from 800 to 3,500 m. 
Although the likelihood of occurrence within the Project Area remains 
very low, the sperm whale was included as an affected species due to 
its high seasonal densities east of the Project Area.

Long-Finned Pilot Whale

    Long-finned pilot whales are found from North Carolina and north to 
Iceland, Greenland and the Barents Sea (Hayes et al., 2020). In U.S. 
Atlantic waters the species is distributed principally along the 
continental shelf edge off the northeastern U.S. coast in winter and 
early spring and in late spring, pilot whales move onto Georges Bank 
and into the Gulf of Maine and more northern waters and remain in these 
areas through late autumn (Hayes et al., 2020). Long-finned and short-
finned pilot whales overlap spatially along the mid-Atlantic shelf 
break between Delaware and the southern flank of Georges Bank. Long-
finned pilot whales have occasionally been observed stranded as far 
south as South Carolina, but sightings of long-finned pilot whales 
south of Cape Hatteras would be considered unusual (Hayes et al., 
2020).The main threats to this species include interactions with 
fisheries and habitat issues including exposure to high levels of 
polychlorinated biphenyls and chlorinated pesticides, and toxic metals 
including mercury, lead, cadmium, and selenium (Hayes et al., 2020).

Short-Finned Pilot Whale

    As described above, long-finned and short-finned pilot whales 
overlap spatially along the mid-Atlantic shelf break between Delaware 
and the southern flank of Georges Bank. There is limited information on 
the distribution of short-finned pilot whales; they prefer warmer or 
tropical waters and deeper waters offshore, and in the northeast United 
States, they are often sighted near the Gulf Stream (Hayes et al., 
2020). Short-finned pilot whales have occasionally been observed 
stranded as far north as Massachusetts but north of ~42[deg] N short-
finned pilot whale sightings would be considered unusual while south of 
Cape Hatteras most pilot whales would be expected to be short-finned 
pilot whales (Hayes et al., 2020). In addition, short-finned pilot 
whales are documented along the continental shelf and continental slope 
in the northern Gulf of Mexico (Mullin and Fulling 2003), and they are 
also known from the wider Caribbean. As with long-finned pilot whales, 
the main threats to this species include interactions with fisheries 
and habitat issues including exposure to high levels of polychlorinated 
biphenyls and chlorinated pesticides, and toxic metals including 
mercury, lead, cadmium, and selenium (Hayes et al., 2020).

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 (Hayes et 
al., 2020). 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. The Virginia and North Carolina 
observations appear to represent the southern extent of the species 
range. 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 (Payne 
and Heinemann 1990). Sightings south of Georges Bank, particularly 
around Hudson Canyon, occur year round but at low densities.

Atlantic Spotted Dolphin

    Atlantic spotted dolphins are found in tropical and warm temperate 
waters ranging from southern New England, south to Gulf of Mexico and 
the Caribbean to Venezuela (Hayes et al., 2020). 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 (Hayes et al., 2020). Atlantic spotted dolphins regularly occur 
in the inshore waters south of Chesapeake Bay,

[[Page 11247]]

and near the continental shelf edge and continental slope waters north 
of this region (Payne et al., 1984; Mullin and Fulling, 2003). Atlantic 
spotted dolphins north of Cape Hatteras also associate with the north 
wall of the Gulf Stream and warm-core rings (Hayes et al., 2020). Four 
sightings of Atlantic spotted dolphins were recorded between 2012 and 
2014 during the summer MABS surveys (Williams et al., 2015a,b). There 
are 2 forms of this species, with the larger ecotype inhabiting the 
continental shelf and is usually found inside or near the 200 m 
isobaths (Hayes et al., 2020).

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 100-m and 2,000-m isobaths and over 
prominent underwater topography and east to the mid-Atlantic Ridge 
(Hayes et al., 2020). Common dolphins are distributed in waters off the 
eastern U.S. coast from Cape Hatteras northeast to Georges Bank 
(35[deg] to 42[deg] N) during mid-January to May and move as far north 
as the Scotian Shelf from mid-summer to autumn (CETAP, 1982; Hayes et 
al., 2020; Hamazaki, 2002; Selzer and Payne, 1988).
    The Western North Atlantic offshore stock expected to occur in the 
Project Area. The offshore stock is distributed primarily along the 
outer continental shelf and slope, from Georges Bank to Cape Hatteras 
during the spring and summer (CETAP, 1982; Kenney, 1990). Spatial 
distribution data and genetic studies indicate the coastal morphotype 
comprises multiple stocks distributed throughout coastal and estuarine 
waters of the U.S. East Coast. One such stock, the northern migratory 
coastal stock, ranges from North Carolina to New York and is likely to 
occur in the Project Area (Hayes et al., 2020). There is likely some 
interaction between the northern and southern migratory stocks, but the 
bottlenose dolphins in the Project Area are expected to be from the 
northern migratory stock (Hayes et al., 2020). All coastal stocks are 
listed as depleted (Hayes et al., 2020). The best abundance estimates 
for the northern migratory coastal stock of common bottlenose dolphin 
is 6,639 individuals (Hayes et al. 2020).

Bottlenose Dolphin

    There are two distinct bottlenose dolphin morphotypes in the 
western North Atlantic: The coastal and offshore forms (Hayes et al., 
2020). The offshore form is distributed primarily along the outer 
continental shelf and continental slope in the Northwest Atlantic Ocean 
from Georges Bank to the Florida Keys. The coastal morphotype is 
morphologically and genetically distinct from the larger, more robust 
morphotype that occupies habitats further offshore. Spatial 
distribution data, tag-telemetry studies, photo-ID studies and genetic 
studies demonstrate the existence of a distinct Northern Migratory 
coastal stock of coastal bottlenose dolphins (Hayes et al., 2020).
    North of Cape Hatteras, there is separation of the offshore and 
coastal morphotypes across bathymetric contours during summer months. 
Aerial surveys flown from 1979 through 1981 indicated a concentration 
of common bottlenose dolphins in waters <25 m deep that corresponded 
with the coastal morphotype, and an area of high abundance along the 
shelf break that corresponded with the offshore stock (Hayes et al., 
2020). Torres et al. (2003) found a statistically significant break in 
the distribution of the morphotypes; almost all dolphins found in 
waters >34 m depth and >34 km from shore were of the offshore 
morphotype. The coastal stock is best defined by its summer 
distribution, when it occupies coastal waters from the shoreline to the 
20-m isobath between Virginia and New York (Hayes et al., 2020). This 
stock migrates south during late summer and fall, and during colder 
months it occupies waters off Virginia and North Carolina (Hayes et 
al., 2020). Therefore, during the summer, dolphins found inside the 20-
m isobath in the Project Area are likely to belong to the coastal 
stock, while those found in deeper waters or observed during cooler 
months belong to the offshore stock.

Risso's Dolphin

    Risso's dolphins are large dolphins with a characteristic blunt 
head and light coloration, often with extensive scarring. They are 
widely distributed in tropical and temperate seas. In the Western North 
Atlantic they occur from Florida to eastern Newfoundland (Leatherwood 
et al., 1976; Baird and Stacey, 1991). Off the U.S. Northeast Coast, 
Risso's dolphins are primarily distributed along the continental shelf, 
but can also be found swimming in shallower waters to the mid-shelf 
(Hayes et al., 2020).
    Risso's dolphins occur along the continental shelf edge from Cape 
Hatteras to Georges Bank during spring, summer, and autumn. In winter, 
they are distributed in the Mid-Atlantic from the continental shelf 
edge outward (Hayes et al., 2020). The majority of sightings during the 
2011 surveys occurred along the continental shelf break with generally 
lower sighting rates over the continental slope (Palka, 2012). Risso's 
dolphins can be found in Mid-Atlantic waters year-round and are more 
likely to be encountered offshore given their preference for deeper 
waters along the shelf edge. However, previous surveys have commonly 
observed this species in shallower waters, making it possible this 
species could be encountered in the Project Area, particularly in 
summer when they are more abundant in this region (Curtice et al., 
2019; Williams et al., 2015a, b; Hayes et al., 2020).

Harbor Porpoise

    Harbor porpoises commonly occur throughout Massachusetts Bay from 
September through April. During the fall and spring, harbor porpoises 
are widely distributed along the east coast from New Jersey to Maine. 
During the summer, the porpoises are concentrated in the Northern Gulf 
of Maine and Southern Bay of Fundy in water depths <150 m. In winter, 
densities increase in the waters off New Jersey to North Carolina and 
decrease in the waters from New York to New Brunswick; however, 
specific migratory timing or routes are not apparent. Although still 
considered uncommon, harbor porpoises were regularly detected offshore 
of Maryland during winter and spring surveys (Wingfield et al., 2017). 
They were the second most frequently sighted cetacean during the NJDEP 
EBS, with 90 percent of the sightings during the winter, three during 
the spring, and one during the summer (Whitt et al., 2015). The lack of 
sightings during the fall was attributed to low visibility conditions 
during those months, but available data indicate this species is likely 
present offshore New Jersey during fall and winter (Whitt et al., 
2015).
    In the Lease Area, only the Gulf of Maine/Bay of Fundy stock may be 
present. This stock is found in U.S. and Canadian Atlantic waters and 
is concentrated in the northern Gulf of Maine and southern Bay of Fundy 
region, generally in waters less than 150 m deep (Hayes et al., 2020). 
They are seen from the coastline to deep waters (>1,800 m; Westgate et 
al. 1998), although the majority of the population is found over the 
continental shelf (Hayes et al., 2020).
    The main threat to the species is interactions with fisheries, with 
documented take in the U.S. northeast sink gillnet, mid-Atlantic 
gillnet, and northeast bottom trawl fisheries and in the Canadian 
herring weir fisheries (Hayes et al. 2020).

[[Page 11248]]

Harbor Seal

    The harbor seal is found in all nearshore waters of the North 
Atlantic and North Pacific Oceans and adjoining seas above about 
30[deg] N (Burns, 2009). In the western North Atlantic, harbor seals 
are distributed from the eastern Canadian Arctic and Greenland south to 
southern New England and New York, and occasionally to the Carolinas 
(Hayes et al., 2020). The harbor seals within the Project Area are part 
of the single Western North Atlantic stock. Between September and May 
they undergo seasonal migrations into southern New England and the Mid-
Atlantic (Hayes et al., 2020). The NJDEP EBS reported one harbor seal 
offshore New Jersey in June 2008 in approximately 18 m of water (Whitt 
et al., 2015). Three other pinnipeds were observed during this study, 
however, they could not be identified to species level.
    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. A total of 
1,593 reported strandings (of all species) had occurred as of the 
writing of this document. 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

    There are three major populations of gray seals found in the world; 
eastern Canada (western North Atlantic stock), northwestern Europe and 
the Baltic Sea. Gray seals in the survey area belong to the western 
North Atlantic stock. The range for this stock is thought to be from 
New Jersey to Labrador. Though gray seals are not regularly sighted 
offshore of Delaware their range has been expanding southward in recent 
years, and they have been observed recently as far south as the barrier 
islands of Virginia. Current population trends show that gray seal 
abundance is likely increasing in the U.S. Atlantic EEZ (Hayes et al., 
2020). Although the rate of increase is unknown, surveys conducted 
since their arrival in the 1980s indicate a steady increase in 
abundance in both Maine and Massachusetts (Hayes et al., 2020). It is 
believed that recolonization by Canadian gray seals is the source of 
the U.S. population (Hayes et al., 2020). As described above, elevated 
seal mortalities, including gray seals, have occurred from Maine to 
Virginia since July 2018. This event has been declared a UME, with 
phocine distemper virus identified as the main pathogen found in the 
seals. 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.

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).
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).
    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 (both phocid) 
species) have the reasonable potential to co-occur with the proposed 
survey activities. Please refer to Table 2. Of the cetacean

[[Page 11249]]

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 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.

Background on Sound

    Sound is a physical phenomenon consisting of minute vibrations that 
travel through a medium, such as air or water, and is generally 
characterized by several variables. Frequency describes the sound's 
pitch and is measured in Hz or kHz, while sound level describes the 
sound's intensity and is measured in dB. Sound level increases or 
decreases exponentially with each dB of change. The logarithmic nature 
of the scale means that each 10-dB increase is a 10-fold increase in 
acoustic power (and a 20-dB increase is then a 100-fold increase in 
power). A 10-fold increase in acoustic power does not mean that the 
sound is perceived as being 10 times louder, however. Sound levels are 
compared to a reference sound pressure (micro-Pascal) to identify the 
medium. For air and water, these reference pressures are ``re: 20 micro 
Pascals ([micro]Pa)'' and ``re: 1 [micro]Pa,'' respectively. Root mean 
square (RMS) is the quadratic mean sound pressure over the duration of 
an impulse. RMS is calculated by squaring all the sound amplitudes, 
averaging the squares, and then taking the square root of the average 
(Urick 1975). RMS 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. 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 rather than by peak 
pressures.
    When sound travels (propagates) from its source, its loudness 
decreases as the distance traveled by the sound increases. Thus, the 
loudness of a sound at its source is higher than the loudness of that 
same sound one km away. Acousticians often refer to the loudness of a 
sound at its source (typically referenced to one meter from the source) 
as the source level and the loudness of sound elsewhere as the received 
level (i.e., typically the receiver). For example, a humpback whale 3 
km from a device that has a source level of 230 dB may only be exposed 
to sound that is 160 dB loud, depending on how the sound travels 
through water (e.g., spherical spreading (6 dB reduction with doubling 
of distance) was used in this example). As a result, it is important to 
understand the difference between source levels and received levels 
when discussing the loudness of sound in the ocean or its impacts on 
the marine environment.
    As sound travels from a source, its propagation in water is 
influenced by various physical characteristics, including water 
temperature, depth, salinity, and surface and bottom properties that 
cause refraction, reflection, absorption, and scattering of sound 
waves. Oceans are not homogeneous and the contribution of each of these 
individual factors is extremely complex and interrelated. The physical 
characteristics that determine the sound's speed through the water will 
change with depth, season, geographic location, and with time of day 
(as a result, in actual active sonar operations, crews will measure 
oceanic conditions, such as sea water temperature and depth, to 
calibrate models that determine the path the sonar signal will take as 
it travels through the ocean and how strong the sound signal will be at 
a given range along a particular transmission path). As sound travels 
through the ocean, the intensity associated with the wavefront 
diminishes, or attenuates. This decrease in intensity is referred to as 
propagation loss, also commonly called transmission loss.

Acoustic Impacts

    Geophysical surveys may temporarily impact marine mammals in the 
area due to elevated in-water sound levels. Marine mammals are 
continually exposed to many sources of sound. Naturally occurring 
sounds such as lightning, rain, sub-sea earthquakes, and biological 
sounds (e.g., snapping shrimp, whale songs) are widespread throughout 
the world's oceans. Marine mammals produce sounds in various contexts 
and use sound for various biological functions including, but not 
limited to: (1) Social interactions, (2) foraging, (3) orientation, and 
(4) predator detection. Interference with producing or receiving these 
sounds may result in adverse impacts. Audible distance, or received 
levels, of sound depends on the nature of the sound source, ambient 
noise conditions, and the sensitivity of the receptor to the sound 
(Richardson et al., 1995). Type and significance of marine mammal 
reactions to sound are likely dependent on a variety of factors 
including, but not limited to: (1) The behavioral state of the animal 
(e.g., feeding, traveling, etc.), (2) frequency of the sound, (3) 
distance between the animal and the source, and (4) the level of the 
sound relative to ambient conditions (Southall et al., 2007).
    When considering the influence of various kinds of sound on the 
marine environment, it is necessary to understand that different kinds 
of marine life are sensitive to different frequencies of sound. Current 
data indicate that not all marine mammal species have equal hearing 
capabilities (Richardson et al., 1995; Wartzok and Ketten, 1999; Au and 
Hastings, 2008). Animals are less sensitive to sounds at the outer 
edges of their functional hearing range and are more sensitive to a 
range of frequencies within the middle of their functional hearing 
range.

Hearing Impairment

    Marine mammals may experience temporary or permanent hearing 
impairment when exposed to loud sounds. Hearing impairment is 
classified by temporary threshold shift (TTS) and permanent threshold 
shift (PTS). PTS is considered auditory injury (Southall et al., 2007) 
and occurs in a specific frequency range and amount. Irreparable damage 
to the inner or outer cochlear hair cells may cause PTS; however, other 
mechanisms are also involved, such as exceeding the elastic limits of 
certain tissues and membranes in the middle and inner ears and 
resultant changes in the chemical composition of the inner ear fluids 
(Southall et al., 2007). There are no empirical data for onset of PTS 
in any marine mammal; therefore, PTS-onset must be estimated from TTS-
onset measurements and from the rate of TTS growth with increasing 
exposure levels above the level eliciting TTS-onset. PTS is presumed to 
be likely if the hearing threshold is reduced by >=40 dB (that is, 40 
dB of TTS).

[[Page 11250]]

Temporary Threshold Shift (TTS)

    TTS is the mildest form of hearing impairment that can occur during 
exposure to a loud sound (Kryter 1985). While experiencing TTS, the 
hearing threshold rises, and a sound must be louder in order to be 
heard. At least in terrestrial mammals, TTS can last from minutes or 
hours to (in cases of strong TTS) days, can be limited to a particular 
frequency range, and can occur to varying degrees (i.e., a loss of a 
certain number of dBs of sensitivity). For sound exposures at or 
somewhat above the TTS threshold, hearing sensitivities in both 
terrestrial and marine mammals recover rapidly after exposure to the 
noise ends.
    Marine mammal hearing plays a critical role in communication with 
conspecifics and in 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 takes place during a time when the animal is traveling 
through the open ocean, 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 a time when communication is 
critical for successful mother/calf interactions could have more 
serious impacts if it were in the same frequency band as the necessary 
vocalizations and of a severity that it impeded communication. The fact 
that animals exposed to levels and durations of sound that would be 
expected to result in this physiological response would also be 
expected to have behavioral responses of a comparatively more severe or 
sustained nature is also notable and potentially of more importance 
than the simple existence of a TTS.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin, beluga whale (Delphinapterus leucas), harbor 
porpoise, and Yangtze finless porpoise (Neophocaena phocaenoides)) 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 (e.g., 
Finneran et al., 2002 and 2010; Nachtigall et al., 2004; Kastak et al., 
2005; Lucke et al., 2009; Mooney et al., 2009a,b; Popov et al., 2011; 
Finneran and Schlundt, 2010). In general, harbor seals (Kastak et al., 
2005; Kastelein et al., 2012a) and harbor porpoises (Lucke et al., 
2009; Kastelein et al., 2012b) have a lower TTS onset than other 
measured pinniped or cetacean species. However, even for these animals, 
which are better able to hear higher frequencies and may be more 
sensitive to higher frequencies, exposures on the order of 
approximately 170 dB<INF>rms</INF> or higher for brief transient 
signals are likely required for even temporary (recoverable) changes in 
hearing sensitivity that would likely not be categorized as 
physiologically damaging (Lucke et al., 2009). 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 Finneran (2015).
    Scientific literature highlights the inherent complexity of 
predicting TTS onset in marine mammals, as well as the importance of 
considering exposure duration when assessing potential impacts (Mooney 
et al., 2009a, 2009b; Kastak et al., 2007). Generally, with sound 
exposures of equal energy, quieter sounds (lower sound pressure levels 
(SPL)) of longer duration were found to induce TTS onset more than 
louder sounds (higher SPL) of shorter duration (more similar to sub-
bottom profilers). For intermittent sounds, less threshold shift will 
occur than from a continuous exposure with the same energy (some 
recovery will occur between intermittent exposures) (Kryter et al., 
1966; Ward 1997). For sound exposures at or somewhat above the TTS-
onset threshold, hearing sensitivity recovers rapidly after exposure to 
the sound ends; intermittent exposures recover faster in comparison 
with continuous exposures of the same duration (Finneran et al., 2010). 
NMFS considers TTS as Level B harassment that is mediated by 
physiological effects on the auditory system.
    Animals in the survey area during the HRG survey are unlikely to 
incur TTS hearing impairment due to the characteristics of the sound 
sources, which include relatively low source levels (176 to 205 dB re 1 
[micro]Pa-m) 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 many of HRG survey devices 
planned for use (Table 1) makes it unlikely that an animal would be 
exposed more than briefly during the passage of the vessel.

Masking

    Masking is the obscuring of sounds of interest to an animal by 
other sounds, typically at similar frequencies. Marine mammals are 
highly dependent on sound, and their ability to recognize sound signals 
amid other sound is important in communication and detection of both 
predators and prey (Tyack 2000). Background ambient sound may interfere 
with or mask the ability of an animal to detect a sound signal even 
when that signal is above its absolute hearing threshold. Even in the 
absence of anthropogenic sound, the marine environment is often loud. 
Natural ambient sound includes contributions from wind, waves, 
precipitation, other animals, and (at frequencies above 30 kHz) thermal 
sound resulting from molecular agitation (Richardson et al., 1995).
    Background sound may also include anthropogenic sound, and masking 
of natural sounds can result when human activities produce high levels 
of background sound. Conversely, if the background level of underwater 
sound is high (e.g., on a day with strong wind and high waves), an 
anthropogenic sound source would not be detectable as far away as would 
be possible under quieter conditions and would itself be masked. 
Ambient sound is highly

[[Page 11251]]

variable on continental shelves (Myrberg 1978; Desharnais et al., 
1999). This results in a high degree of variability in the range at 
which marine mammals can detect anthropogenic sounds.
    Although masking is a phenomenon which may occur naturally, the 
introduction of loud anthropogenic sounds into the marine environment 
at frequencies important to marine mammals increases the severity and 
frequency of occurrence of masking. For example, if a baleen whale is 
exposed to continuous low-frequency sound from an industrial source, 
this would reduce the size of the area around that whale within which 
it can hear the calls of another whale. The components of background 
noise that are similar in frequency to the signal in question primarily 
determine the degree of masking of that signal. In general, little is 
known about the degree to which marine mammals rely upon detection of 
sounds from conspecifics, predators, prey, or other natural sources. In 
the absence of specific information about the importance of detecting 
these natural sounds, it is not possible to predict the impact of 
masking on marine mammals (Richardson et al., 1995). In general, 
masking effects are expected to be less severe when sounds are 
transient than when they are continuous. Masking is typically of 
greater concern for those marine mammals that utilize low-frequency 
communications, such as baleen whales, because of how far low-frequency 
sounds propagate.
    Marine mammal communications would not likely be masked appreciably 
by the sub-bottom profiler signals given the directionality of the 
signals for most HRG survey equipment types planned for use (Table 1) 
and the brief period when an individual mammal is likely to be within 
its beam.

Non-Auditory Physical Effects (Stress)

    Classic stress responses begin when an animal's central nervous 
system perceives a potential threat to its homeostasis. That perception 
triggers stress responses regardless of whether a stimulus actually 
threatens the animal; the mere perception of a threat is sufficient to 
trigger a stress response (Moberg 2000; Seyle 1950). Once an animal's 
central nervous system perceives a threat, it mounts a biological 
response or defense that consists of a combination of the four general 
biological defense responses: behavioral responses, autonomic nervous 
system responses, neuroendocrine responses, or immune responses.
    In the case of many stressors, an animal's first and sometimes most 
economical (in terms of biotic costs) response is behavioral avoidance 
of the potential stressor or avoidance of continued exposure to a 
stressor. An animal's second line of defense to stressors involves the 
sympathetic part of the autonomic nervous system and the classical 
``fight or flight'' response which includes the cardiovascular system, 
the gastrointestinal system, the exocrine glands, and the adrenal 
medulla to produce changes in heart rate, blood pressure, and 
gastrointestinal activity that humans commonly associate with 
``stress.'' These responses have a relatively short duration and may or 
may not have significant long-term effect on an animal's welfare.
    An animal's third line of defense to stressors involves its 
neuroendocrine systems; the system that has received the most study has 
been the hypothalamus-pituitary-adrenal system (also known as the HPA 
axis in mammals). Unlike stress responses associated with the autonomic 
nervous system, virtually all neuro-endocrine 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 (Moberg 1987; Rivier 1995), reduced 
immune competence (Blecha 2000), and behavioral disturbance. Increases 
in the circulation of glucocorticosteroids (cortisol, corticosterone, 
and aldosterone in marine mammals; see Romano et al., 2004) have been 
long been equated with stress.
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and distress is the biotic 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 a 
risk to the animal's welfare. 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 biotic 
functions, which impairs those functions that experience the diversion. 
For example, when mounting a stress response diverts energy away from 
growth in young animals, those animals may experience stunted growth. 
When mounting a stress response diverts energy from a fetus, an 
animal's reproductive success and its fitness will suffer. In these 
cases, the animals will have entered a pre-pathological or pathological 
state which is called ``distress'' (Seyle 1950) or ``allostatic 
loading'' (McEwen and Wingfield 2003). This pathological state will 
last until the animal replenishes its biotic reserves sufficient to 
restore normal function. Note that these examples involved a long-term 
(days or weeks) stress response exposure to stimuli.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses have also been documented 
fairly well through controlled experiments; because this physiology 
exists in every vertebrate that has been studied, it is not surprising 
that stress responses and their costs have been documented in both 
laboratory and free-living animals (for examples see, Holberton et al., 
1996; Hood et al., 1998; Jessop et al., 2003; Krausman et al., 2004; 
Lankford et al., 2005; Reneerkens et al., 2002; Thompson and Hamer, 
2000). Information has also been collected on the physiological 
responses of marine mammals to exposure to anthropogenic sounds (Fair 
and Becker 2000; Romano et al., 2004). 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.
    Studies of other marine animals and terrestrial animals would also 
lead us to expect some marine mammals to experience physiological 
stress responses and, perhaps, physiological responses that would be 
classified as ``distress'' upon exposure to high-frequency, mid-
frequency, and low-frequency sounds. Trimper et al. (1998) reported on 
the physiological stress responses of osprey to low-level aircraft 
noise while Krausman et al. (2004) reported on the auditory and 
physiology stress responses of endangered Sonoran pronghorn to military 
overflights. Smith et al. (2004a, 2004b), for example, identified 
noise-induced physiological transient stress responses in hearing-
specialist fish (i.e., goldfish) that accompanied short- and long-term 
hearing losses. Welch and Welch (1970) reported physiological and 
behavioral stress responses that accompanied damage to the inner ears 
of fish and several mammals.
    Hearing is one of the primary senses marine mammals use to gather 
information about their environment and to communicate with 
conspecifics. Although empirical information on the relationship 
between sensory impairment (TTS, PTS, and acoustic masking) on marine 
mammals remains limited, it seems reasonable to assume that reducing an 
animal's ability to gather information about its environment and to 
communicate with

[[Page 11252]]

other members of its species would be stressful for animals that use 
hearing as their primary sensory mechanism. Therefore, NMFS assumes 
that acoustic exposures sufficient to trigger onset PTS or TTS would be 
accompanied by physiological stress responses because terrestrial 
animals exhibit those responses under similar conditions (NRC 2003). 
More importantly, marine mammals might experience stress responses at 
received levels lower than those necessary to trigger onset TTS. Based 
on empirical studies of the time required to recover from stress 
responses (Moberg 2000), NMF also assumes that stress responses are 
likely to persist beyond the time interval required for animals to 
recover from TTS and might result in pathological and pre-pathological 
states that would be as significant as behavioral responses to TTS.
    In general, there are few data on the potential for strong, 
anthropogenic underwater sounds to cause non-auditory physical effects 
in marine mammals. The available data do not allow identification of a 
specific exposure level above which non-auditory effects can be 
expected (Southall et al., 2007). There is currently no definitive 
evidence that any of these effects occur even for marine mammals in 
close proximity to an anthropogenic sound source. In addition, marine 
mammals that show behavioral avoidance of survey vessels and related 
sound sources are unlikely to incur non-auditory impairment or other 
physical effects. NMFS does not expect that the generally short-term, 
intermittent, and transitory HRG and geotechnical activities would 
create conditions of long-term, continuous noise and chronic acoustic 
exposure leading to long-term physiological stress responses in marine 
mammals.

Behavioral Disturbance

    Behavioral disturbance may include a variety of effects, including 
subtle changes in behavior (e.g., minor or brief avoidance of an area 
or changes in vocalizations), more conspicuous changes in similar 
behavioral activities, and more sustained and/or potentially severe 
reactions, such as displacement from or abandonment of high-quality 
habitat. Behavioral responses to sound are highly variable and context-
specific and any reactions depend on numerous intrinsic and extrinsic 
factors (e.g., species, state of maturity, experience, current 
activity, reproductive state, auditory sensitivity, time of day), as 
well as the interplay between factors (e.g., Richardson et al., 1995; 
Wartzok et al., 2003; Southall et al., 2007; Weilgart 2007; Archer et 
al., 2010). Behavioral reactions can vary not only among individuals 
but also within an individual, depending on previous experience with a 
sound source, context, and numerous other factors (Ellison et al., 
2012), and can vary depending on characteristics associated with the 
sound source (e.g., whether it is moving or stationary, number of 
sources, distance from the source). Please see Appendices B-C of 
Southall et al. (2007) for a review of studies involving marine mammal 
behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. As noted, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; NRC 2003; Wartzok et al., 2003). Controlled experiments with 
captive marine mammals have shown 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 seismic airguns or acoustic 
harassment devices) have been varied but often consist of avoidance 
behavior or other behavioral changes suggesting discomfort (Morton and 
Symonds, 2002; see also Richardson et al., 1995; Nowacek et al., 2007).
    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 NMFS 
describes 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,b). 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

[[Page 11253]]

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, 2005b, 2006; Gailey et 
al., 2007).
    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 vocalizations (Miller et 
al., 2000; Fristrup et al., 2003; Foote et al., 2004), while North 
Atlantic 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 stressor 
and is one of the most obvious manifestations of disturbance in marine 
mammals (Richardson et al., 1995). For example, gray whales are known 
to change direction--deflecting from customary migratory paths--in 
order to avoid noise from seismic surveys (Malme et al., 1984). 
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 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). 
Disruptions 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.
    Marine mammals are likely to avoid the HRG survey activity, 
especially the naturally shy harbor porpoise, while harbor seals might 
be attracted to survey vessels out of curiosity. However, because the 
sub-bottom profilers and other HRG survey equipment operate 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 HRG-related impacts 
within the survey area.
    NMFS has also considered the potential for severe behavioral 
responses such as stranding and associated indirect injury or mortality 
from Skipjack's use of HRG survey equipment, on the basis of 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 other 
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

[[Page 11254]]

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 
may be 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.

Tolerance

    Numerous studies have shown that underwater sounds from industrial 
activities are often readily detectable by marine mammals in the water 
at distances of many km. However, other studies have shown that marine 
mammals at distances more than a few km away often show no apparent 
response to industrial activities of various types (Miller et al., 
2005). This is often true even in cases when the sounds must be readily 
audible to the animals based on measured received levels and the 
hearing sensitivity of that mammal group. Although various baleen 
whales, toothed whales, and (less frequently) pinnipeds have been shown 
to react behaviorally to underwater sound from sources such as airgun 
pulses or vessels under some conditions, at other times, mammals of all 
three types have shown no overt reactions (e.g., Malme et al., 1986; 
Richardson et al., 1995; Madsen and Mohl 2000; Croll et al., 2001; 
Jacobs and Terhune 2002; Madsen et al., 2002; Miller et al., 2005). In 
general, pinnipeds seem to be more tolerant of exposure to some types 
of underwater sound than are baleen whales. Richardson et al. (1995) 
found that vessel sound does not seem to affect pinnipeds that are 
already in the water. Richardson et al. (1995) went on to explain that 
seals on haul-outs sometimes respond strongly to the presence of 
vessels and at other times appear to show considerable tolerance of 
vessels, and Brueggeman et al. (1992) observed ringed seals (Pusa 
hispida) hauled out on ice pans displaying short-term escape reactions 
when a ship approached within 0.16-0.31 miles (0.25-0.5 km). Due to the 
relatively high vessel traffic in the survey area it is possible that 
marine mammals are habituated to noise (e.g., DP thrusters) from 
vessels in the area.

Vessel Strike

    Ship strikes of marine mammals can cause major 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 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 Skipjack's proposed survey activities. Marine 
mammals would be able to easily avoid the survey vessel due to the slow 
vessel speed. Further, Skipjack 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.

Marine Mammal Habitat

    The HRG survey equipment will not contact the seafloor and does not 
represent a source of pollution. NMFS is 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. Any avoidance of the area on the part of marine 
mammal prey would be expected to be short term and temporary.
    Because of the temporary nature of the disturbance, and the 
availability of similar habitat and resources (e.g., prey species) 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. NMFS has preliminarily determined that impacts on marine 
mammal habitat from the proposed activities will be temporary, 
insignificant, and discountable.

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 noise from certain

[[Page 11255]]

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 or and/or mortality is neither anticipated, 
even absent mitigation, nor proposed to be authorized. Below NMFS 
describes how the take is estimated.
    Generally speaking, NMFS estimates 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. NMFS notes that while 
these basic factors can contribute to a basic calculation to provide an 
initial prediction of takes, additional information that can 
qualitatively inform take estimates is also sometimes available (e.g., 
previous monitoring results or average group size). Below, NMFS 
describes 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 NMFS considers Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 [mu]Pa (rms) for continuous (e.g., 
vibratory pile-driving, drilling) and above 160 dB re 1 [mu]Pa (rms) 
for non-explosive impulsive (e.g., seismic airguns) or intermittent 
(e.g., scientific sonar) sources. Skipjack's proposed activity includes 
the use of intermittent sources (HRG equipment) and therefore the 160 
dB re 1 [mu]Pa (rms) 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) (Technical Guidance, 2018) identifies dual 
criteria to assess auditory injury (Level A harassment) to five 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise from two different types of sources 
(impulsive or non-impulsive). Skipjack's proposed activity includes the 
use of impulsive (e.g., sparkers and boomers) and non-impulsive (e.g., 
CHIRP) sources.
    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.
Note: Peak sound pressure (Lpk) has a reference value of 1 [micro]Pa, and cumulative sound exposure level (LE)
  has a reference value of 1[micro]Pa\2\s. In this Table, thresholds are abbreviated to reflect American
  National Standards Institute standards (ANSI 2013). However, peak sound pressure is defined by ANSI as
  incorporating frequency weighting, which is not the intent for this Technical Guidance. Hence, the subscript
  ``flat'' is being included to indicate peak sound pressure should be flat weighted or unweighted within the
  generalized hearing range. The subscript associated with cumulative sound exposure level thresholds indicates
  the designated marine mammal auditory weighting function (LF, MF, and HF cetaceans, and PW and OW pinnipeds)
  and that the recommended accumulation period is 24 hours. The cumulative sound exposure level thresholds could
  be exceeded in a multitude of ways (i.e., varying exposure levels and durations, duty cycle). When possible,
  it is valuable for action proponents to indicate the conditions under which these acoustic thresholds will be
  exceeded.

Ensonified Area

    Here, NMFS describes 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.
    NMFS has developed a user-friendly methodology for determining the 
rms sound pressure level (SPL<INF>rms</INF>) at the 160-dB isopleth for 
the purposes of estimating the extent of Level B harassment isopleths 
associated with HRG survey equipment (NMFS, 2020). This methodology 
incorporates frequency and some directionality to refine estimated 
ensonified zones. For sources that operate with different beam widths, 
the maximum beam width was used (see Table 1). The lowest frequency of 
the source was used when calculating the absorption coefficient (Table 
1).
    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

[[Page 11256]]

estimate isopleth distances to the Level A and Level B harassment 
thresholds. In 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 and the sound levels 
associated with those HRG equipment types.
    Results of modeling using the methodology described above indicated 
that, of the HRG survey equipment planned for use by Skipjack that has 
the potential to result in Level B harassment of marine mammals, sound 
produced by the Applied Acoustics Dura-Spark UHD sparkers and GeoMarine 
Geo-Source sparker would propagate furthest to the Level B harassment 
threshold (141 m; Table 5). As described above, only a portion of 
Skipjack's survey activity days will employ sparkers or boomers; 
therefore, for the purposes of the exposure analysis, it was assumed 
that sparkers would be the dominant acoustic source for 50 of the total 
200 survey activity days. For the remaining 150 survey days, the TB 
Chirp III (48 m) was assumed to be the dominant source. Thus, the 
distances to the isopleths corresponding to the threshold for Level B 
harassment for sparkers (141 m) and the TB Chirp III (48 m) were used 
as the basis of the take calculation for all marine mammals 25 percent 
and 75 percent of survey activity days, respectively. This is a 
conservative approach, as the actual sources used on individual survey 
days may produce smaller harassment distances.
    When the NMFS Technical Guidance was first published in 2016, 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, NMFS 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. NMFS 
notes that because of some of the assumptions included in the methods 
used for these tools, it is anticipated 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 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 Table 6 
and the resulting isopleths are reported in Table 7.

                                                Table 5--User Spreadsheet Inputs for Non-Impulsive, Non-Parametric, Shallow Sub-Bottom Profilers
                                                                                         [CHIRP sonars]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
               Device                         EdgeTech 216                    Edgetech 424                    Edgetech 512                  GeoPulse 5430                Teledyne Chirp III
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                        (D1) Mobile source; non-        (D1) Mobile source; non-        (D1) Mobile source; non-       (D1) Mobile source; non-       (D1) Mobile source; non-
        Spreadsheet tab used             impulsive, intermittent         impulsive, intermittent        impulsive, intermittent        impulsive, intermittent        impulsive, intermittent
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Frequency used for Weighting Factor  2; 16; 16; 6.2................  4; 24; 24; 6.2................  1.7; 12; 12; 6.2.............  2; 17; 17; 6.2...............  2; 7; 7; 6.2
 Adjustment (kHz) 1 2.
Source Level (RMS SPL).............  195...........................  176...........................  179..........................  196..........................  197
Source Velocity (m/sec)............  2.057.........................  2.057.........................  2.057........................  2.057........................  2.057
Pulse Duration (sec)...............  0.02..........................  0.0034........................  0.009........................  0.05.........................  0.06
1/Repetition rate (sec)............  0.17..........................  0.5...........................  0.125........................  0.1..........................  0.07
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Values for WFA represented = (LFC; MFC; HFC; PPW).
\2\ WFAs were selected in the User Spreadsheet for each marine mammal hearing group based on estimated hearing sensitivities of each group and the operational frequency of the source.


                                                           Table 6--User Spreadsheet Inputs for Impulsive, Medium Sub-Bottom Profilers
                                                                                      [Sparkers & Boomers]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
            Device               AA, Dura-spark UHD (400       AA, Dura-spark UHD       GeoMarine, Geo-Source     GeoMarine Geo-Source 200  GeoMarine Geo-Source 200-   AA, triple plate S Boom
-------------------------------      tips, 500 J) \1\            (400+400) \1\        dual 400 tip sparker (800   tip sparker (400 J) \1\    400 tip sparker (400 J)       (700-1,000 J) \2\
                               ------------------------------------------------------           J) \1\          ---------------------------            \1\            --------------------------
                                                                                     ---------------------------                           ---------------------------
     Spreadsheet tab used          (F1) Mobile source:        (F1) Mobile source:        (F1) Mobile source:        (F1) Mobile source:        (F1) Mobile source:        (F1) Mobile source:
                                 impulsive, intermittent    impulsive, intermittent    impulsive, intermittent    impulsive, intermittent    impulsive, intermittent    impulsive, intermittent
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Frequency used for Weighting    1........................  1........................  1.5......................  1........................  1........................  3.4
 Factor Adjustment (kHz) *.
Source Level (RMS SPL; PK SPL)  203; 211.................  203; 211.................  203; 211.................  203; 211.................  203; 211.................  205; 211
Source Velocity (m/sec).......  2.057....................  2.057....................  2.057....................  2.057....................  2.057....................  2.057
Pulse Duration (sec)..........  0.0011...................  0.0011...................  0.0011...................  0.0011...................  0.0011...................  0.0006
1/Repetition rate (sec).......  0.25.....................  0.25.....................  0.25.....................  0.25.....................  0.25.....................  0.25
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ The Dura-spark measurements and specifications provided in Crocker and Fratantonio (2016) were used for all sparker systems proposed for the survey. The data provided in Crocker and
  Fratantonio (2016) represent the most applicable data for similar sparker systems with comparable operating methods and settings when manufacturer or other reliable measurements are not
  available.
\2\ Crocker and Fratantonio (2016) provide S-Boom measurements using two different power sources (CSP-D700 and CSP-N). The CSP-D700 power source was used in the 700 J measurements but not in
  the 1,000 J measurements. The CSP-N source was measured for both 700 J and 1,000 J operations but resulted in a lower SL; therefore, the single maximum SL value was used for both operational
  levels of the S Boom.


[[Page 11257]]


Table 7--Modeled Radial Distances From HRG Survey Equipment to Isopleths
             Corresponding to Level B Harassment Thresholds
------------------------------------------------------------------------
                                                       Distance to Level
                                                         B harassment
                                                         threshold (m)
                       Source                        -------------------
                                                      (SPLrms threshold)
 
------------------------------------------------------------------------
Non-impulsive, Non-parametric, Shallow SBPs:
    ET 216 CHIRP....................................                   9
    ET 424 CHIRP....................................                   4
    ET 512i CHIRP...................................                   6
    GeoPulse 5430...................................                  21
    TB CHIRP III....................................                  48
Impulsive, Medium SBPs:
    AA Triple plate S-Boom (700/1,000 J)............                  34
    AA, Dura-spark UHD (500 J/400 tip)..............                 141
    AA, Dura-spark UHD 400+400......................                 141
    GeoMarine, Geo-Source dual 400 tip sparker......                 141
    GeoMarine, Geo-Source 200 tip sparker...........                 141
    GeoMarine, Geo-Source 200-400 tip sparker.......                 141
------------------------------------------------------------------------

    Isopleth distances to Level A harassment thresholds for all types 
of HRG equipment and all marine mammal functional hearing groups were 
modeled using the NMFS User Spreadsheet and NMFS Technical Guidance 
(2018). The dual criteria (peak SPL and SEL<INF>cum</INF>) were applied 
to all HRG sources using the modeling methodology as described above, 
and the isopleth distances for each functional hearing group were then 
carried forward in the exposure analysis. Distances to the Level A 
harassment threshold based on the larger of the dual criteria (peak SPL 
and SEL<INF>cum</INF>) are shown in Table 7. Modeled distances to 
isopleths corresponding to the Level A harassment thresholds are very 
small for all marine mammals and stocks (<5 m) with the exception of HF 
cetaceans (36.5 m from GeoPulse 5430). Note that the modeled distances 
to isopleths corresponding to the Level A harassment threshold are also 
assumed to be conservative. Level A harassment would also be more 
likely to occur at close approach to the sound source or as a result of 
longer duration exposure to the sound source, and mitigation measures--
including a 100 m exclusion zone for harbor porpoises--are expected to 
minimize the potential for close approach or longer duration exposure 
to active HRG sources. In addition, harbor porpoises are a notoriously 
shy species which is known to avoid vessels. Harbor porpoise would also 
be expected to avoid a sound source prior to that source reaching a 
level that would result in injury (Level A harassment). Therefore, NMFS 
has determined that the potential for take by Level A harassment of 
harbor porpoises is so low as to be discountable.
    Given the information described above regarding porpoises and based 
on the very small Level A harassment zones for all marine mammal 
species and stocks that may be impacted by the proposed activities, the 
potential for any marine mammals to be taken by Level A harassment is 
considered so low as to be discountable. Therefore, Skipjack did not 
request and NMFS does not propose to authorize the take by Level A 
harassment of any marine mammals.

Marine Mammal Occurrence

    In this section NMFS provides information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations.
    The habitat-based density models produced by the Duke University 
Marine Geospatial Ecology Laboratory (Roberts et al., 2016a,b, 2017, 
2018, 2020) 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, 2020) incorporates 
aerial and shipboard line-transect survey data from NMFS and other 
organizations and incorporates data from 8 physiographic and 16 dynamic 
oceanographic and 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 based on 
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 the most recent model results for all taxa 
(Roberts et al., 2016, 2017, 2018, 2020). The updated models 
incorporate additional sighting data, including sightings from the NOAA 
Atlantic Marine Assessment Program for Protected Species (AMAPPS) 
surveys (e.g., NEFSC & SEFSC, 2011, 2012, 2014a, 2014b, 2015, 2016).
    For the exposure analysis, density data from Roberts et al. (2016, 
2017, 2018, 2020) were mapped using a geographic information system 
(GIS). Density grid cells that included any portion of the proposed 
survey area were selected for all survey months.
    Densities from each of the selected density blocks were averaged 
for each month available to provide monthly density estimates for each 
species (when available based on the temporal resolution of the model 
products), along with the average annual density (Table 8).

[[Page 11258]]



  Table 8--Estimated Monthly and Average Annual Density (Animals/km\2\) of Potentially Affected Marine Mammals Within the Project Area Based on Monthly
                                                                 Habitat Density Models
                                                       [Roberts et al. 2016; Roberts, 2018, 2020]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                                 Average
                                                                                                                                                 annual
              Species                 Jan      Feb      Mar      Apr      May      Jun      Jul      Aug      Sep      Oct      Nov      Dec     density
                                                                                                                                                 (km-2)
 
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low-Frequency Cetaceans:
    Fin whale.....................   0.0010   0.0008   0.0015   0.0020   0.0017   0.0012   0.0005   0.0004   0.0011   0.0014   0.0010   0.0009    0.0011
    Sei whale.....................   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000    0.0000
    Minke whale...................   0.0002   0.0002   0.0002   0.0009   0.0010   0.0005   0.0001   0.0000   0.0001   0.0003   0.0001   0.0001    0.0003
    Humpback whale................   0.0013   0.0006   0.0006   0.0005   0.0005   0.0004   0.0001   0.0001   0.0002   0.0004   0.0004   0.0014    0.0005
    North Atlantic right whale....   0.0037   0.0042   0.0043   0.0028   0.0002   0.0000   0.0000   0.0000   0.0000   0.0000   0.0003   0.0020    0.0015
Mid-Frequency Cetaceans:
    Sperm whale...................   0.0000   0.0000   0.0000   0.0000   0.0000   0.0001   0.0001   0.0001   0.0000   0.0001   0.0000   0.0000    0.0000
    Atlantic white-sided dolphin..   0.0017   0.0009   0.0012   0.0028   0.0035   0.0022   0.0006   0.0003   0.0008   0.0026   0.0036   0.0034    0.0020
    Atlantic spotted dolphin......   0.0017   0.0017   0.0017   0.0017   0.0017   0.0017   0.0017   0.0017   0.0017   0.0017   0.0017   0.0017    0.0017
    Common bottlenose dolphin        0.0134   0.0088   0.0125   0.0193   0.1224   0.1138   0.1361   0.1663   0.0800   0.0713   0.0524   0.0201    0.0680
     (Offshore) \1\...............
    Common bottlenose dolphin        0.0317   0.0271   0.0444   0.0910   0.5921   0.4623   0.5903   0.6439   0.2388   0.2015   0.1335   0.0459    0.2585
     (Migratory) \1\..............
    Short-finned pilot whale \2\..   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003    0.0003
    Long-finned pilot whale \2\...   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003   0.0003    0.0003
    Risso's dolphin...............   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000   0.0000    0.0000
    Common dolphin................   0.0071   0.0035   0.0040   0.0092   0.0167   0.0110   0.0125   0.0143   0.0109   0.0109   0.0200   0.0152    0.0113
High-Frequency Cetaceans:
    Harbor porpoise...............   0.0261   0.0247   0.0225   0.0095   0.0031   0.0000   0.0000   0.0000   0.0000   0.0005   0.0153   0.0535    0.0129
Pinnipeds \3\:
    Gray seal.....................   0.0003   0.0003   0.0003   0.0003   0.0003   0.0007   0.0007   0.0007   0.0003   0.0003   0.0003   0.0003    0.0004
    Harbor seal...................   0.0003   0.0003   0.0003   0.0003   0.0003   0.0007   0.0007   0.0007   0.0003   0.0003   0.0003   0.0003    0.0004
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Bottlenose dolphin stocks were delineated based on the 20-m isobath as identified in NMFS 2017 Stock Assessment Report; all density blocks falling
  inland of the 20-m depth contour were assumed to belong to the migratory coastal stock, and those beyond this depth were assumed to belong to the
  offshore stock.
\2\ Roberts (2018) only provides density estimates for ``generic'' pilot whales. It is assumed that each species has density levels that are equivalent
  to the generic pilot whale Density levels.
\3\ Seal densities are not given by individual months or species, instead, seasons are divided as summer (June, July, August) and Winter (September-May)
  and applied to ``generic'' seals; as a result, reported seasonal densities for spring and fall are the same and are not provided for each species
  (Roberts 2018). Densities were evenly split between both species.

    Level B harassment exposures were estimated by multiplying the 
average annual density of each species (Table 8) by the daily ZOI that 
was estimated to be ensonified to an SPL<INF>rms</INF> exceeding 160 dB 
re 1 [micro]Pa (Table 9), times the number of operating days expected 
for the survey in each area assessed.

Take Calculation and Estimation

    Here NMFS describes 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 Level B 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 daily area is multiplied by the mean 
annual density of a given marine mammal species. This value is then 
multiplied by the number of proposed vessel days.
    The estimated potential daily active survey distance of 70 km was 
used as the estimated areal coverage over a 24-hour period. This 
distance accounts for the vessel traveling at roughly 4 knots and only 
for periods during which equipment <180 kHz is in operation. A vessel 
traveling 4 knots can cover approximately 110 km per day; however, 
based on data from 2017, 2018, and 2019 surveys, survey coverage over a 
24-hour period is closer to 70 km per day. For daylight only vessels, 
the distance is reduced to 35 km per day. To maintain the potential for 
24-hour surveys, the Level B harassment ZOIs provided in Table 9 were 
calculated for each source based on the Level B harassment threshold 
distances in Table 7 with a 24-hour (70 km) operational period.

    Table 9--Calculated Zone of Influence (ZOI) Encompassing Level B
  Thresholds for Each Sound Source or Comparable Sound Source Category
------------------------------------------------------------------------
                         Source                            Level B ZOI
--------------------------------------------------------     (km\2\)
                                                        ----------------
                     Hearing group                             All
------------------------------------------------------------------------
ET 216 CHIRP...........................................              1.3
ET 424 CHIRP...........................................              0.6
ET 512i CHIRP..........................................              0.8
GeoPulse 5430..........................................              2.9
TB CHIRP III...........................................              6.7
AA Triple plate S-Boom (700-1,000 J)...................              4.8
AA, Dura-spark UHD.....................................             19.8
AA, Dura-spark UHD 400+400.............................             19.8
GeoMarine, Geo-Source dual 400 tip Sparker.............             19.8
------------------------------------------------------------------------
AA = Applied Acoustics; CHIRP = Compressed High-Intensity Radiated
  Pulse; ET = EdgeTech; HF = high-frequency; J = joules; LF = low-
  frequency; MF = mid-frequency; PW = phocid pinnipeds in water; SBP =
  sub-bottom profiler; TB = Teledyne Benthos; UHD = ultra-high
  definition.

    Level B exposures were estimated by multiplying the average annual 
density of each species (Table 7) (Roberts et al., 2016; Roberts, 2018) 
by the daily ZOI that was estimated to be ensonified to an 
SPL<INF>rms</INF> exceeding 160 dB re 1 [micro]Pa

[[Page 11259]]

(Table 9), times the number of operating days expected for the survey 
in each area assessed. As described previously, it was assumed that 
that sparker systems with 141-m Level B harassment isopleths would 
operate for 50 survey days and the non-sparker TB CHIRP III with 48-m 
Level B harassment isopleth would operate for the remaining 150 survey 
days. The results of these calculations are shown in Table 10.

                          Table 10--Summary of Take Numbers Proposed for Authorization
----------------------------------------------------------------------------------------------------------------
                                                                                   Level B takes       Max %
                             Species                                 Abundance          \1\         population
----------------------------------------------------------------------------------------------------------------
Low-Frequency Cetaceans:
    Fin whale...................................................           7,418               2            0.03
    Sei whale...................................................           6,292           0 (1)            0.02
    Minke whale.................................................          24,202           0 (2)            0.01
    Humpback whale..............................................           1,396               2            0.14
    North Atlantic right whale..................................             428               3            0.70
Mid-Frequency Cetaceans:
    Sperm whale \3\.............................................           4,349           0 (3)            0.07
    Atlantic white-sided dolphin................................          93,233               4            0.00
    Atlantic spotted dolphin....................................          39,921       4 (2,000)            5.00
    Common bottlenose dolphin \2\:
        Offshore Stock..........................................          62,851             135            0.21
        Migratory Stock.........................................           6,639             516            7.77
    Pilot Whales \3\:
        Short-finned pilot whale................................          28,924          0 (10)            0.03
        Long-finned pilot whale.................................          39,215          0 (10)            0.03
    Risso's dolphin.............................................          35,493          0 (30)            0.08
    Common dolphin..............................................         178,825         24 (70)            0.04
High-Frequency Cetaceans:
    Harbor porpoise.............................................          95,543              22            0.03
Pinnipeds:
    Seals \4\:
        Gray seal...............................................          27,131          0 (10)            0.04
        Harbor seal.............................................          75,834          0 (10)            0.01
----------------------------------------------------------------------------------------------------------------
\1\ Parenthesis denote changes from calculated take estimates.
\2\ Roberts et al. (2016) does not provide density estimates for individual stocks of common bottlenose
  dolphins; therefore, stock densities were delineated using the 20-m isobath.
\3\ Roberts (2018) only provides density estimates for ``generic'' pilot whales and seals; therefore, an equal
  potential for takes has been assumed either for species or stocks within the larger group.
\4\ Roberts (2018) only provides density estimates for ``generic'' seals; therefore, densities were split evenly
  between the two species.

    No takes were calculated for the sei whale, minke whale, sperm 
whale, short- and long-finned pilot whale, or Risso's dolphin. However, 
based on anticipated species distributions and data from previous 
surveys conducted in the DE WEA, it is possible that these species 
could be encountered. Therefore, Skipjack based its take requests on 
estimated group sizes for these species (1 for sei whales, 2 for minke 
whales, 3 for sperm whales, 10 for short- and long-finned pilot whales, 
and 30 for Risso's dolphins). For species with no modeled exposures, 
requested takes for HRG surveys are based on mean group sizes derived 
from the following references:

<bullet> Sei whale: Kenney and Vigness-Raposa, 2010;
<bullet> Minke whale: Kenney and Vigness-Raposa, 2020;
<bullet> Sperm whale: Barkaszi and Kelly, 2018;
<bullet> Short- and long-finned pilot whales: Kenney and Vigness-
Raposa, 2010; and
<bullet> Risso's dolphin: Barkaszi and Kelly, 2018.

    NMFS concurred with this approach and based its proposed 
authorization for takes of these species on Skipjack's requests. 
Additionally, the number of takes proposed in Table 10 for Atlantic 
white-sided dolphin, bottlenose dolphin, harbor porpoise are equivalent 
to the numbers requested by Skipjack.
    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 close to zero takes. The marine mammal 
monitoring report associated with the previous IHA issued to Skipjack 
in this survey area (84 FR 66156; December 3, 2019) did not record any 
takes of seals. However, the proposed survey area for this proposed IHA 
includes a portion of Delaware Bay which is not covered by Roberts et 
al. (2018) and was not included as part of the previous IHA. Therefore, 
Skipjack did not request take of any harbor or gray seals. However, 
since seals are known to occur in the Bay, mostly during winter months, 
NMFS is conservatively proposing to authorize 10 takes of each species 
by Level B harassment of both harbor and gray seals.
    Skipjack had requested 4 takes of spotted dolphin and 24 takes of 
common dolphin by Level B harassment. However, recent HRG surveys in 
the Mid-Atlantic area off the coast of Virginia have recorded 
unexpectedly large numbers of both Atlantic spotted dolphin and common 
dolphin. These events have led NMFS to modify another offshore wind 
energy company's existing IHA (85 FR 81879; December 17, 2020) in order 
to accommodate larger take numbers. The spotted dolphins had been 
recorded at a rate of up 15 per day while common dolphins were recorded 
at a rate of 62 animals in a single week. Note that there were many 
days in which there were no sightings of spotted dolphins and that all 
of the 62 common dolphin sightings occurred during a single week. The 
previous Skipjack marine mammal monitoring report from this area 
recorded up to 8 common dolphins over 23 days of active surveying (0.35 
animals/day). Given this data, NMFS will assume that 0.35 common 
dolphins could be exposed within the Level B

[[Page 11260]]

harassment zone per day over 200 days resulting in the 70 proposed 
takes of common dolphin by Level B harassment. NMFS will also assume 
that there could be up to 10 exposures of spotted dolphin per day 
resulting in the proposed 2000 takes by Level B harassment.
    Note that Skipjack submitted a marine mammal monitoring report 
under the previous IHA covering the period of June 4, 2020 through June 
26, 2020. Over the 23-day monitoring period there were 110 sightings 
consisting of 112 individual animals. Only three bottlenose dolphins 
were recorded as occurring within estimated Level B harassment zones 
which is well below the 1,465 takes that were authorized. However, due 
to a range of factors only 23 actual survey days occurred out of 200 
that were anticipated.

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, NMFS 
carefully considers 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.

Mitigation for Marine Mammals and Their Habitat

    NMFS proposes the following mitigation measures be implemented 
during Skipjack's proposed marine site characterization surveys.

Marine Mammal Exclusion Zones and Harassment Zones

    Marine mammal exclusion zones (EZ) would be established around the 
HRG survey equipment and monitored by protected species observers 
(PSOs):
    <bullet> 500 m EZ for North Atlantic right whales during use of all 
acoustic sources;
    <bullet> 100 m EZ for all marine mammals, with certain exceptions 
specified below, during operation of impulsive acoustic sources (boomer 
and/or sparker).
    If a marine mammal is detected approaching or entering the EZs 
during the HRG survey, the vessel operator would adhere to the shutdown 
procedures described below to minimize noise impacts on the animals. 
These stated requirements will be included in the site-specific 
training to be provided to the survey team.

Pre-Clearance of the Exclusion Zones

    Skipjack would implement a 30-minute pre-clearance period of the 
exclusion zones prior to the initiation of ramp-up of HRG equipment. 
During this period, the exclusion zone will be monitored by the PSOs, 
using the appropriate visual technology. Ramp-up may not be initiated 
if any marine mammal(s) is within its respective exclusion zone. If a 
marine mammal is observed within an exclusion zone during the pre-
clearance period, ramp-up may not begin until the animal(s) has been 
observed exiting its respective exclusion zone or until an additional 
time period has elapsed with no further sighting (i.e., 15 minutes for 
small odontocetes and seals, and 30 minutes for all other species).

Ramp-Up of Survey Equipment

    When technically feasible, a ramp-up procedure would be used for 
HRG survey equipment capable of adjusting energy levels at the start or 
restart 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 
vacate the area prior to the commencement of survey equipment operation 
at full power.
    A ramp-up would begin with the powering up of the smallest acoustic 
HRG equipment at its lowest practical power output appropriate for the 
survey. When technically feasible, the power would then be gradually 
turned up and other acoustic sources would be added.
    Ramp-up activities will be delayed if a marine mammal(s) enters its 
respective exclusion zone. Ramp-up will continue if the animal has been 
observed exiting its respective exclusion zone or until an additional 
time period has elapsed with no further sighting (i.e., 15 minutes for 
small odontocetes and seals and 30 minutes for all other species).
    Activation of survey equipment through ramp-up procedures may not 
occur when visual observation of the pre-clearance zone is not expected 
to be effective (i.e., during inclement conditions such as heavy rain 
or fog).

Shutdown Procedures

    An immediate shutdown of the impulsive HRG survey equipment would 
be required if a marine mammal is sighted entering or within its 
respective exclusion zone. The vessel operator must comply immediately 
with any call for shutdown by the Lead PSO. Any disagreement between 
the Lead PSO and vessel operator should be discussed only after 
shutdown has occurred. Subsequent restart of the survey equipment can 
be initiated if the animal has been observed exiting its respective 
exclusion zone or until an additional time period has elapsed (i.e., 30 
minutes for all other species).
    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 
Level B harassment zone (48 m, non-impulsive; 141 m impulsive), 
shutdown would occur.
    If the acoustic source is shut down for reasons other than 
mitigation (e.g., mechanical difficulty) for less than 30 minutes, it 
may be activated again without ramp-up if PSOs have maintained constant 
observation and no detections of any marine mammal have occurred within 
the respective exclusion zones. If the acoustic source is shut down for 
a period longer than 30 minutes and PSOs have maintained constant 
observation, then pre-clearance and ramp-up procedures will be 
initiated as described in the previous section.
    The shutdown requirement would be waived for small delphinids of 
the following genera: Delphinus, Lagenorhynchus, Stenella, and Tursiops

[[Page 11261]]

and seals. Specifically, if a delphinid from the specified genera or a 
pinniped is visually detected approaching the vessel (i.e., to bow 
ride) or towed equipment, shutdown is not required. Furthermore, 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 must use best 
professional judgement in making the decision to call for a shutdown. 
Additionally, shutdown is required if a delphinid or pinniped detected 
in the exclusion zone and belongs to a genus other than those 
specified.

Vessel Strike Avoidance

    Skipjack will ensure that vessel operators and crew maintain a 
vigilant watch for cetaceans and pinnipeds and slow down or stop their 
vessels to avoid striking these species. Survey vessel crew members 
responsible for navigation duties will receive site-specific training 
on marine mammals sighting/reporting and vessel strike avoidance 
measures. Vessel strike avoidance measures would include the following, 
except under circumstances when complying with these requirements would 
put the safety of the vessel or crew at risk:
    <bullet> 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 based on the appropriate separation 
distance 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.
    <bullet> All vessels (e.g., source vessels, chase vessels, supply 
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 including seasonal management 
areas (SMAs) and dynamic management areas (DMAs) when in effect;
    <bullet> All vessels greater than or equal to 19.8 m in overall 
length operating from November 1 through April 30 will operate at 
speeds of 10 knots or less while transiting to and from Project Area;
    <bullet> All vessels must reduce their speed to 10 knots or less 
when mother/calf pairs, pods, or large assemblages of cetaceans are 
observed near a vessel.
    <bullet> 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.
    <bullet> All vessels must maintain a minimum separation distance of 
100 m from sperm whales and all other baleen whales.
    <bullet> All vessels must, to the maximum extent practicable, 
attempt to maintain a minimum separation distance of 50 m from all 
other marine mammals, with an understanding that at times this may not 
be possible (e.g., for animals that approach the vessel).
    <bullet> When marine mammals 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 marine mammals 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.
    <bullet> These requirements do not apply in any case where 
compliance would create an imminent and serious threat to a person or 
vessel or to the extent that a vessel is restricted in its ability to 
maneuver and, because of the restriction, cannot comply.

Seasonal Operating Requirements

    Members of the monitoring team will consult NMFS North Atlantic 
right whale reporting system and Whale Alert, as able, for the presence 
of North Atlantic right whales throughout survey operations, and for 
the establishment of a DMA. If NMFS should establish a DMA in the Lease 
Areas during the survey, the vessels will abide by speed restrictions 
in the DMA.
    Project-specific training will be conducted for all vessel crew 
prior to the start of a survey and during any changes in crew such that 
all survey personnel are fully aware and understand the mitigation, 
monitoring, and reporting requirements. Prior to implementation with 
vessel crews, the training program will be provided to NMFS for review 
and approval. 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 member understands and will 
comply with the necessary requirements throughout the survey 
activities.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means of 
effecting the least practicable impact on marine mammal 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:
    <bullet> Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
    <bullet> 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);
    <bullet> Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or

[[Page 11262]]

cumulative), other stressors, or cumulative impacts from multiple 
stressors;
    <bullet> How anticipated responses to stressors impact either: (1) 
Long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
    <bullet> Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
    <bullet> Mitigation and monitoring effectiveness.

Proposed Monitoring Measures

    Visual monitoring will be performed by qualified, NMFS-approved 
PSOs, the resumes of whom will be provided to NMFS for review and 
approval prior to the start of survey activities. Skipjack would employ 
independent, dedicated, trained PSOs, meaning that the PSOs must (1) be 
employed by a third-party observer provider, (2) 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 (3) have successfully completed an 
approved PSO training course appropriate for their designated task. On 
a case-by-case basis, non-independent observers may be approved by NMFS 
for limited, specific duties in support of approved, independent PSOs 
on smaller vessels with limited crew capacity operating in nearshore 
waters.
    The PSOs will be responsible for monitoring the waters surrounding 
each survey vessel to the farthest extent permitted by sighting 
conditions, including exclusion zones, during all HRG survey 
operations. PSOs will visually monitor and identify marine mammals, 
including those approaching or entering the established exclusion zones 
during survey activities. It will be the responsibility of the Lead PSO 
on duty to communicate the presence of marine mammals as well as to 
communicate the action(s) that are necessary to ensure mitigation and 
monitoring requirements are implemented as appropriate.
    During all HRG survey operations (e.g., any day on which use of an 
HRG source is planned to occur), a minimum of one PSO must be on duty 
during daylight operations on each survey vessel, conducting visual 
observations at all times on all active survey vessels during daylight 
hours (i.e., from 30 minutes prior to sunrise through 30 minutes 
following sunset). Two PSOs will be on watch during nighttime 
operations. The PSO(s) would ensure 360[deg] visual coverage around the 
vessel from the most appropriate observation posts and would conduct 
visual observations using binoculars and/or night vision goggles 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 nearby survey vessels.
    PSOs must be equipped with binoculars and have the ability to 
estimate distance and bearing to detect marine mammals, particularly in 
proximity to exclusion zones. Reticulated binoculars must also be 
available to PSOs for use as appropriate based on conditions and 
visibility to support the sighting and monitoring of marine mammals. 
During nighttime operations, night-vision goggles with thermal clip-ons 
and infrared technology would be used. Position data would be recorded 
using hand-held or vessel GPS units for each sighting.
    During good conditions (e.g., daylight hours; Beaufort sea state 
(BSS) 3 or less), to the maximum extent practicable, PSOs would also 
conduct observations when the acoustic source is not operating for 
comparison of sighting rates and behavior with and without use of the 
active acoustic sources. 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 
behavior that occurs (e.g., noted behavioral disturbances).

Proposed Reporting Measures

    Within 90 days after completion of survey activities or expiration 
of this IHA, whichever comes sooner, 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. All draft 
and final marine mammal and acoustic monitoring reports must be 
submitted to <a href="/cdn-cgi/l/email-protection#4c1c1e6205181c620123222538233e25222b1e293c233e383f0c22232d2d622b233a"><span class="__cf_email__" data-cfemail="0c5c5e2245585c224163626578637e65626b5e697c637e787f4c62636d6d226b637a">[email protected]</span></a> and 
<a href="/cdn-cgi/l/email-protection#8ac3dedaa4daebffe6e3e4efcae4e5ebeba4ede5fc"><span class="__cf_email__" data-cfemail="09405d592759687c6560676c4967666868276e667f">[email protected]</span></a>. The report must contain at minimum, the 
following:

<bullet> PSO names and affiliations
<bullet> Dates of departures and returns to port with port name
<bullet> Dates and times (Greenwich Mean Time) of survey effort and 
times corresponding with PSO effort
<bullet> Vessel location (latitude/longitude) when survey effort begins 
and ends; vessel location at beginning and end of visual PSO duty 
shifts
<bullet> Vessel heading and speed at beginning and end of visual PSO 
duty shifts and upon any line change
<bullet> Environmental conditions while on visual survey (at beginning 
and end of PSO shift and whenever conditions change significantly), 
including wind speed and direction, Beaufort sea state, Beaufort wind 
force, swell height, weather conditions, cloud cover, sun glare, and 
overall visibility to the horizon
<bullet> Factors that may be contributing to impaired observations 
during each PSO shift change or as needed as environmental conditions 
change (e.g., vessel traffic, equipment malfunctions)
<bullet> Survey activity information, such as type of survey equipment 
in operation, acoustic source power output while in operation, and any 
other notes of significance (i.e., pre-clearance survey, ramp-up, 
shutdown, end of operations, etc.)

    If a marine mammal is sighted, the following information should be 
recorded:
    <bullet> Watch status (sighting made by PSO on/off effort, 
opportunistic, crew, alternate vessel/platform);
    <bullet> PSO who sighted the animal;
    <bullet> Time of sighting;
    <bullet> Vessel location at time of sighting;
    <bullet> Water depth;
    <bullet> Direction of vessel's travel (compass direction);
    <bullet> Direction of animal's travel relative to the vessel;
    <bullet> Pace of the animal;

[[Page 11263]]

    <bullet> Estimated distance to the animal and its heading relative 
to vessel at initial sighting;
    <bullet> Identification of the animal (e.g., genus/species, lowest 
possible taxonomic level, or unidentified); also note the composition 
of the group if there is a mix of species;
    <bullet> Estimated number of animals (high/low/best);
    <bullet> Estimated number of animals by cohort (adults, yearlings, 
juveniles, calves, group composition, etc.);
    <bullet> Description (as many distinguishing features as possible 
of each individual seen, including length, shape, color, pattern, scars 
or markings, shape and size of dorsal fin, shape of head, and blow 
characteristics);
    <bullet> Detailed behavior observations (e.g., number of blows, 
number of surfaces, breaching, spyhopping, diving, feeding, traveling; 
as explicit and detailed as possible; note any observed changes in 
behavior);
    <bullet> Animal's closest point of approach and/or closest distance 
from the center point of the acoustic source;
    <bullet> Platform activity at time of sighting (e.g., deploying, 
recovering, testing, data acquisition, other);
    <bullet> Description of any actions implemented in response to the 
sighting (e.g., delays, shutdown, ramp-up, speed or course alteration, 
etc.) and time and location of the action.
    If a North Atlantic right whale is observed at any time by PSOs or 
personnel on any project vessels, during surveys or during vessel 
transit, Skipjack must immediately report sighting information to the 
NMFS North Atlantic Right Whale Sighting Advisory System: (866) 755-
6622. North Atlantic right whale sightings in any location may also be 
reported to the U.S. Coast Guard via channel 16.
    In the event that Skipjack personnel discover an injured or dead 
marine mammal, Skipjack would report the incident to the NMFS Office of 
Protected Resources (OPR) and the NMFS New England/Mid-Atlantic 
Stranding Coordinator as soon as feasible. The report would include the 
following information:
    <bullet> Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    <bullet> Species identification (if known) or description of the 
animal(s) involved;
    <bullet> Condition of the animal(s) (including carcass condition if 
the animal is dead);
    <bullet> Observed behaviors of the animal(s), if alive;
    <bullet> If available, photographs or video footage of the 
animal(s); and
    <bullet> General circumstances under which the animal was 
discovered.
    In the unanticipated event of a ship strike of a marine mammal by 
any vessel involved in the activities covered by the IHA, Skipjack 
would report the incident to the NMFS OPR and the NMFS New England/Mid-
Atlantic Stranding Coordinator as soon as feasible. The report would 
include the following information:
    <bullet> Time, date, and location (latitude/longitude) of the 
incident;
    <bullet> Species identification (if known) or description of the 
animal(s) involved;
    <bullet> Vessel's speed during and leading up to the incident;
    <bullet> Vessel's course/heading and what operations were being 
conducted (if applicable);
    <bullet> Status of all sound sources in use;
    <bullet> 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;
    <bullet> Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, visibility) immediately preceding the 
strike;
    <bullet> Estimated size and length of animal that was struck;
    <bullet> Description of the behavior of the marine mammal 
immediately preceding and following the strike;
    <bullet> If available, description of the presence and behavior of 
any other marine mammals immediately preceding the strike;
    <bullet> 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
    <bullet> 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. NMFS also assesses 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 10, given that NMFS expects the anticipated effects of the 
proposed survey to be similar in nature. Where there are meaningful 
differences between species or stocks--as is the case of the North 
Atlantic right whale--they are included as separate subsections below. 
NMFS does not anticipate that serious injury or mortality would occur 
as a result from HRG surveys, even in the absence of mitigation, and no 
serious injury or mortality is proposed to be authorized. As discussed 
in the Potential Effects section, non-auditory physical effects and 
vessel strike are not expected to occur. NMFS expects that all 
potential takes would be in the form of short-term Level B behavioral 
harassment in the form of temporary avoidance of the area or decreased 
foraging (if such activity was occurring), reactions that are 
considered to be of low severity and with no lasting biological 
consequences (e.g., Southall et al., 2007). Even repeated Level B 
harassment of some small subset of an overall stock is unlikely to 
result in any significant realized decrease in viability for the 
affected individuals, and thus would not result in any adverse impact 
to the stock as a whole. As described above, Level A harassment is not 
expected to occur given the nature of the operations, the estimated 
size of the Level A harassment zones, and the required shutdown zones 
for certain activities.
    In addition to being temporary, the maximum expected harassment 
zone around a survey vessel is 141 m; 75 percent of survey days would 
include activity with a reduced acoustic harassment zone of 48 m per 
vessel, producing expected effects of particularly low severity. 
Therefore, the ensonified area surrounding each vessel

[[Page 11264]]

is relatively small compared to the overall distribution of the animals 
in the area and their use of the habitat. Feeding behavior is not 
likely to be significantly impacted as prey species are mobile and are 
broadly distributed throughout the survey area; therefore, marine 
mammals that may be temporarily displaced during survey activities are 
expected to be able to resume foraging once they have moved away from 
areas with disturbing levels of underwater noise. Because of the 
temporary nature of the disturbance and 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.
    There are no rookeries, mating or calving grounds known to be 
biologically important to marine mammals within the proposed survey 
area and there are no feeding areas known to be biologically important 
to marine mammals within the proposed survey area. There is no 
designated critical habitat for any ESA-listed marine mammals in the 
proposed survey area.

North Atlantic Right Whales

    The status of the North Atlantic right whale population is of 
heightened concern and, therefore, merits additional analysis. As noted 
previously, elevated North Atlantic right whale mortalities began in 
June 2017 and there is an active UME. Overall, preliminary findings 
support human interactions, specifically vessel strikes and 
entanglements, as the cause of death for the majority of right whales. 
The proposed survey area overlaps a migratory corridor Biologically 
Important Area (BIA) for North Atlantic right whales (effective March-
April and November-December) that extends from Massachusetts to Florida 
(LeBrecque et al., 2015). Off the coast of Delaware, this migratory BIA 
extends from the coast to beyond the shelf break. Due to the fact that 
that the proposed survey activities are temporary and the spatial 
extent of sound produced by the survey would be very small relative to 
the spatial extent of the available migratory habitat in the BIA, right 
whale migration is not expected to be impacted by the proposed survey. 
Given the relatively small size of the ensonified area, it is unlikely 
that prey availability would be adversely affected by HRG survey 
operations. Required vessel strike avoidance measures will also 
decrease risk of ship strike during migration; no ship strike is 
expected to occur during Skipjack's proposed activities. Additionally, 
only very limited take by Level B harassment of North Atlantic right 
whales has been requested and is being proposed by NMFS as HRG survey 
operations are required to maintain a 500 m EZ and shutdown if a North 
Atlantic right whale is sighted at or within the EZ. The 500 m shutdown 
zone for right whales is conservative, considering the Level B 
harassment isopleth for the most impactful acoustic source (i.e., 
GeoMarine Geo-Source 400 tip sparker) is estimated to be 141 m, and 
thereby minimizes the potential for behavioral harassment of this 
species. As noted previously, Level A harassment is not expected due to 
the small PTS zones associated with HRG equipment types proposed for 
use. NMFS does not anticipate North Atlantic right whales takes that 
would result from Skipjack's proposed activities would impact annual 
rates of recruitment or survival. Thus, any takes that occur would not 
result in population level impacts.

Other Marine Mammal Species With Active UMEs

    As noted previously, there are several active UMEs occurring in the 
vicinity of Skipjack's proposed survey area. 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 stable at approximately 12,000 individuals.
    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.
    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., 2020). The population abundance 
for gray seals in the United States is over 27,000, with an estimated 
abundance, including seals in Canada, of approximately 505,000. In 
addition, the abundance of gray seals is likely increasing in the U.S. 
Atlantic EEZ as well as in Canada (Hayes et al., 2020).
    The required mitigation measures are expected to reduce the number 
and/or severity of proposed takes for all species listed in Table 10, 
including those with active UME's to the level of least practicable 
adverse impact. In particular they would provide animals the 
opportunity to move away from the sound source throughout the survey 
area before HRG survey equipment reaches full energy, thus preventing 
them from being exposed to sound levels that have the potential to 
cause injury (Level A harassment) or more severe Level B harassment. No 
Level A harassment is anticipated, even in the absence of mitigation 
measures, or authorized.
    NMFS expects that takes would be in the form of short-term Level B 
behavioral harassment by way of brief startling reactions and/or 
temporary vacating of the area, or decreased foraging (if such activity 
was occurring)--reactions that (at the scale and intensity anticipated 
here) are considered to be of low severity, with no lasting biological 
consequences. Since both the sources and marine mammals are mobile, 
animals would only be exposed briefly to a small ensonified area that 
might result in take. Additionally, required mitigation measures would 
further reduce exposure to sound that could result in more severe 
behavioral harassment.
    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:
    <bullet> No mortality or serious injury is anticipated or proposed 
for authorization;
    <bullet> No Level A harassment (PTS) is anticipated, even in the 
absence of mitigation measures, or proposed for authorization;
    <bullet> Foraging success is not likely to be significantly 
impacted as effects on species that serve as prey species for marine 
mammals from the survey are expected to be minimal;

[[Page 11265]]

    <bullet> The availability of alternate areas of similar habitat 
value for marine mammals to temporarily vacate the survey area during 
the planned survey to avoid exposure to sounds from the activity;
    <bullet> Take is anticipated to be primarily Level B behavioral 
harassment consisting of brief startling reactions and/or temporary 
avoidance of the survey area;
    <bullet> While the survey area is within areas noted as a migratory 
BIA for North Atlantic right whales, the activities would occur in such 
a comparatively small area such that any avoidance of the survey area 
due to activities would not affect migration. In addition, mitigation 
measures to shutdown at 500 m to minimize potential for Level B 
behavioral harassment would limit any take of the species.
    <bullet> The proposed mitigation measures, including visual 
monitoring and shutdowns, are expected to minimize potential impacts to 
marine mammals.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities.
    NMFS proposes to authorize incidental take of 16 marine mammal 
species (with 17 managed stocks.) The total amount of takes proposed 
for authorization is less than eight percent for one stock (bottlenose 
dolphin northern coastal migratory stock) and less than one percent of 
all other species and stocks, which NMFS preliminarily finds are small 
numbers of marine mammals relative to the estimated overall population 
abundances for those stocks. See Table 10. 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.
    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

    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 NMFS proposes to authorize take for 
endangered or threatened species, in this case with NMFS Greater 
Atlantic Regional Fisheries Office (GARFO).
    The NMFS Office of Protected Resources Permits and Conservation 
Division is proposing to authorize the incidental take of four species 
of marine mammals which are listed under the ESA: The North Atlantic 
right, fin, sei, and sperm whales. The Permits and Conservation 
Division has requested initiation of Section 7 consultation with NMFS 
GARFO for the issuance of this IHA. NMFS will conclude the ESA section 
7 consultation prior to reaching a determination regarding the proposed 
issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to Skipjack for conducting marine site characterization 
surveys off the coast of Delaware for one year from the date of 
issuance, 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 marine 
site characterization 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 
Description of Proposed Activities section of this notice is planned or 
(2) the activities as described in the Description of Proposed 
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:
    <bullet> 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).
    <bullet> 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).
    (2) A preliminary monitoring report showing the results of the 
required

[[Page 11266]]

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: February 19, 2021.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2021-03821 Filed 2-23-21; 8:45 am]
BILLING CODE 3510-22-P


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