[Federal Register Volume 84, Number 188 (Friday, September 27, 2019)]
[Notices]
[Pages 51118-51145]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2019-20997]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

RIN 0648-XR032


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

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

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

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SUMMARY: NMFS has received a request from 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 or 
Maryland. 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 October 
28, 2019.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service. Physical comments should be sent to 
1315 East-West Highway, Silver Spring, MD 20910 and electronic comments 
should be sent to [email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments received electronically, including 
all attachments, must not exceed a 25-

[[Page 51119]]

megabyte file size. Attachments to electronic comments will be accepted 
in Microsoft Word or Excel or Adobe PDF file formats only. All comments 
received are a part of the public record and will generally be posted 
online at www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-other-energy-activities-renewable 
without change. All personal identifying information (e.g., name, 
address) voluntarily submitted by the commenter may be publicly 
accessible. Do not submit confidential business information or 
otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT: Jordan Carduner, Office of Protected 
Resources, NMFS, (301) 427-8401. Electronic copies of the applications 
and supporting documents, as well as a list of the references cited in 
this document, may be obtained by visiting the internet at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-other-energy-activities-renewable. In case of 
problems accessing these documents, please call the contact listed 
above.

SUPPLEMENTARY INFORMATION: 

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are issued or, if the taking is limited to harassment, a notice of a 
proposed incidental take authorization may be provided to the public 
for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of such 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 such 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 evaluate our proposed action (i.e., the promulgation of 
regulations and subsequent issuance of incidental take authorization) 
and alternatives with respect to potential impacts on the human 
environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 of the Companion Manual for NAO 216-6A, 
which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has 
preliminarily determined that the proposed action qualifies to be 
categorically excluded from further NEPA review.
    Information in Skipjack's application and this notice collectively 
provide the environmental information related to proposed issuance of 
these regulations and subsequent incidental take authorization for 
public review and comment. We will review all comments submitted in 
response to this notice prior to concluding our NEPA process or making 
a final decision on the request for incidental take authorization.

Summary of Request

    On July 1, 2019, 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 or Maryland. A revised 
application was received on August 15, 2019. NMFS deemed that request 
to be adequate and complete. Skipjack's request is for the take of 17 
marine mammal species by Level B harassment that would occur over the 
course of 200 survey days. Neither Skipjack nor NMFS expects serious 
injury or mortality to result from this activity and the activity is 
expected to last no more than one year, therefore, an IHA is 
appropriate.

Description of the Proposed Activity

Overview

    Skipjack proposes to conduct marine site characterization surveys, 
including high-resolution geophysical (HRG) and geotechnical 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 either 
Delaware or Maryland.
    The purpose of the marine site characterization surveys are to 
obtain a baseline assessment of seabed/sub-surface soil conditions in 
the Lease Area and cable route corridors to support the siting of 
potential future offshore wind projects. Underwater sound resulting 
from Skipjack's proposed site characterization surveys has the 
potential to result in incidental take of marine mammals in the form of 
behavioral harassment.

Dates and Duration

    The estimated duration of the activity is expected to be up to 200 
survey days between October 2019 through September 2020. This schedule 
is based on 24-hour operations and includes potential down time due to 
inclement weather.

Specific Geographic Region

    Skipjack's survey activities would occur in the Northwest Atlantic 
Ocean within Federal waters. Surveys would occur in the Lease Area and 
along potential submarine cable routes to landfall locations in either 
Delaware or Maryland (see Figure 1 in the IHA application).

Detailed Description of the Specified Activities

    Skipjack's proposed marine site characterization surveys include 
high-resolution geophysical (HRG) and geotechnical survey activities. 
The Lease Area is approximately 106.6 square kilometers (km) (26,341 
acres) and is within the Delaware Wind Energy Area of the Bureau of 
Ocean Energy Management's Mid-Atlantic planning area. Water depths in 
the Lease Area range from 16 to 28 meters (m) (52 to 92 feet (ft)). 
Water depths along the submarine cable corridor in Federal waters range 
from 12 to 28 m (39 to 92 ft). The closest point to shore is 
approximately 18 km (11 miles (mi)) due east from Rehoboth Beach, 
Delaware (see Figure 1 in the IHA application). For the purpose of this 
IHA the Lease Area and submarine cable

[[Page 51120]]

corridor are collectively termed the Project Area.
    Geophysical and shallow geotechnical survey activities are 
anticipated to be supported by as many as five total vessels, with as 
many as three vessels operating concurrently. Survey vessels would 
maintain a speed of approximately 4 knots (kn) while transiting survey 
lines. The proposed HRG and geotechnical survey activities are 
described below. A maximum of 200 total survey days are expected to be 
required to complete the site characterization surveys.

Geotechnical Survey Activities

    Geophysical and shallow geotechnical survey activities are 
anticipated to be supported by vessels which will maintain a speed of 
up to 4 knots (kn) while transiting survey lines. The proposed HRG and 
geotechnical survey activities are described below.

Geotechnical Survey Activities

    Skipjack's proposed geotechnical survey activities would include 
the following:
     Sample boreholes to determine geological and geotechnical 
characteristics of sediments;
     Deep cone penetration tests (CPTs) to determine 
stratigraphy and in situ conditions of the deep surface sediments; and
     Shallow CPTs to determine stratigraphy and in situ 
conditions of the near surface sediments.
    Geotechnical investigation activities are anticipated to be 
conducted from a drill ship equipped with dynamic positioning (DP) 
thrusters. Impact to the seafloor from this equipment will be limited 
to the minimal contact of the sampling equipment, and inserted boring 
and probes.
    In considering whether marine mammal harassment is an expected 
outcome of exposure to a particular activity or sound source, NMFS 
considers the nature of the exposure itself (e.g., the magnitude, 
frequency, or duration of exposure), characteristics of the marine 
mammals potentially exposed, and the conditions specific to the 
geographic area where the activity is expected to occur (e.g., whether 
the activity is planned in a foraging area, breeding area, nursery or 
pupping area, or other biologically important area for the species). We 
then consider the expected response of the exposed animal and whether 
the nature and duration or intensity of that response is expected to 
cause disruption of behavioral patterns (e.g., migration, breathing, 
nursing, breeding, feeding, or sheltering) or injury.
    Geotechnical survey activities would be conducted from a drill ship 
equipped with DP thrusters. DP thrusters would be used to position the 
sampling vessel on station and maintain position at each sampling 
location during the sampling activity. Sound produced through use of DP 
thrusters is similar to that produced by transiting vessels and DP 
thrusters are typically operated either in a similarly predictable 
manner or used for short durations around stationary activities. NMFS 
does not believe acoustic impacts from DP thrusters are likely to 
result in take of marine mammals in the absence of activity- or 
location-specific circumstances that may otherwise represent specific 
concerns for marine mammals (i.e., activities proposed in area known to 
be of particular importance for a particular species), or associated 
activities that may increase the potential to result in take when in 
concert with DP thrusters. In this case, we are not aware of any such 
circumstances. Therefore, NMFS believes the likelihood of DP thrusters 
used during the proposed geotechnical surveys resulting in harassment 
of marine mammals to be so low as to be discountable. As DP thrusters 
are not expected to result in take of marine mammals, these activities 
are not analyzed further in this document.
    Field studies conducted off the coast of Virginia to determine the 
underwater noise produced by CPTs and borehole drilling found that 
these activities did not result in underwater noise levels that 
exceeded current thresholds for Level B harassment of marine mammals 
(Kalapinski, 2015). Given the small size and energy footprint of CPTs 
and boring cores, NMFS believes the likelihood that noise from these 
activities would exceed the Level B harassment threshold at any 
appreciable distance is so low as to be discountable. Therefore, 
geotechnical survey activities, including CPTs and borehole drilling, 
are not expected to result in harassment of marine mammals and are not 
analyzed further in this document.

Geophysical Survey Activities

    Skipjack has proposed that HRG survey operations would be conducted 
continuously 24 hours per day. Based on 24-hour operations, the 
estimated duration of the geophysical survey activities would be 
approximately 200 days (including estimated weather down time). As many 
as three survey vessels may be used concurrently during Skipjack's 
proposed surveys. The geophysical survey activities proposed by 
Skipjack would include the following:
     Shallow Penetration Sub-bottom Profilers (SBP; Chirps) to 
map the near-surface stratigraphy (top 0 to 5 m (0 to 16 ft) of 
sediment below seabed). A chirp system emits sonar pulses that increase 
in frequency over time. The pulse length frequency range can be 
adjusted to meet project variables. Typically mounted on the hull of 
the vessel or from a side pole.
     Medium Penetration SBPs (Boomers) 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. This system is typically 
mounted on a sled and towed behind the vessel.
     Medium Penetration SBPs (Sparkers) to map deeper 
subsurface stratigraphy as needed. Sparkers create acoustic pulses from 
50 Hz to 4 kHz omni-directionally from the source that can penetrate 
several hundred meters into the seafloor. Typically towed behind the 
vessel with adjacent hydrophone arrays to receive the return signals.
     Parametric SBPs, also called sediment echosounders, for 
providing high data density in sub-bottom profiles that are typically 
required for cable routes, very shallow water, and archaeological 
surveys. Typically mounted on the hull of the vessel or from a side 
pole.
     Acoustic Cores to provide multi-aspect acoustic intensity 
imaging to delineate sub-seabed stratigraphy and buried geohazards. 
Although acoustic cores are used for geotechnical investigations, they 
operate acoustic sources (chirps and a parametric sonar) to achieve the 
data collection. They are stationary sourced mounted on the seafloor 
approximately 3.5 m (11.5 ft) above the seabed.
     Ultra-Short Baseline (USBL) Positioning and Global 
Acoustic Positioning System (GAPS) to provide high accuracy ranges by 
measuring the time between the acoustic pulses transmitted by the 
vessel transceiver and the equipment transponder necessary to produce 
the acoustic profile. It is a two-component system with a hull or pole 
mounted transceiver and one to several transponders either on the 
seabed or on the equipment.
     Multibeam Echosounders (MBES) to determine water depths 
and general bottom topography. Multibeam echosounder sonar systems 
project sonar pulses in several angled beams from a transducer mounted 
to a ship's hull. The beams radiate out from the transducer in a fan-
shaped pattern orthogonally to the ship's direction.
     Side-scan Sonar (SSS) for seabed sediment classification 
purposes and to

[[Page 51121]]

identify natural and man-made acoustic targets on the seafloor. The 
sonar device emits conical or fan-shaped pulses down toward the 
seafloor in multiple beams at a wide angle, perpendicular to the path 
of the sensor through the water. The acoustic return of the pulses is 
recorded in a series of cross-track slices, which can be joined to form 
an image of the sea bottom within the swath of the beam. They are 
typically towed beside or behind the vessel or from an autonomous 
vehicle.
    Table 1 identifies the representative survey equipment that may be 
used in support of planned geophysical survey activities. HRG surveys 
are expected to use several equipment types concurrently in order to 
collect multiple aspects of geophysical data along one transect. 
Selection of equipment combinations is based on specific survey 
objectives.

                                                          Table 1--Summary of Geophysical Survey Equipment Proposed for Use by Skipjack
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                                                                                                                Sound level
                                                              Operating frequency     Sound level (SLrms dB    (SLpk dB re 1   Pulse duration (width)    Repetition
             Equipment                   Source type                 (kHz)              re 1 [micro]Pa m)      [micro]Pa m)        (millisecond)          rate (Hz)       Beamwidth (degrees)
 
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                                                                              Shallow Sub-Bottom Profilers (Chirps)
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Teledyne Benthos Chirp III--TTV     Non-impulsive,         2 to 7..................  197....................               -  5 to 60................              15  100.
 170.                                mobile, intermittent.
EdgeTech SB 216 (2000DS or 3200     Non-impulsive,         2 to 16, 2 to 8.........  195....................               -  20.....................               6  24.
 top unit).                          mobile, intermittent.
EdgeTech 424......................  Non-impulsive,         4 to 24.................  176....................               -  3.4....................               2  71.
                                     mobile, intermittent.
EdgeTech 512......................  Non-impulsive,         0.7 to 12...............  179....................               -  9......................               8  80.
                                     mobile, intermittent.
GeoPulse 5430A....................  Non-impulsive,         2 to 17.................  196....................  ..............  50.....................              10  55.
                                     mobile, intermittent.
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                                                                                 Parametric Sub-Bottom Profilers
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Innomar SES[dash]2000 Medium 100    Non-impulsive,         85 to 115...............  247....................               -  0.07 to 2..............          40-100  1-3.5.
 SBP.                                mobile, intermittent.
Innomar SES[dash]2000 Standard &    Non-impulsive,         85 to 115...............  236....................               -  0.07 to 2..............              60  1-3.5.
 Plus.                               mobile, intermittent.
Innomar SES[dash]2000 Medium 70...  Non-impulsive,         60 to 80................  241....................               -  0.1 to 2.5.............              40  1-3.5.
                                     mobile, intermittent.
Innomar SES[dash]2000 Quattro.....  Non-impulsive,         85 to 115...............  245....................               -  0.07 to 1..............              60  1-3.5.
                                     mobile, intermittent.
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                                                                        Medium Sub-Bottom Profilers (Sparkers & Boomers)
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GeoMarine Geo-Source 800J Sparker.  Impulsive, Mobile....  0.05 to 5...............  203....................             213  3.4....................            0.41  Omni.
GeoMarine Geo-Source 600J Sparker.  Impulsive, Mobile....  0.2 to 5................  201....................             212  5.0....................            0.41  Omni.
GeoMarine Geo-Source 400J Sparker.  Impulsive, Mobile....  0.2 to 5................  195....................             208  7.2....................            0.41  Omni.
GeoResource 800J Sparker System...  Impulsive, Mobile....  0.05 to 5...............  203....................             213  3.4....................            0.41  Omni.
Applied Acoustics Duraspark 400...  Impulsive, Mobile....  0.3 to 1.2..............  203....................             211  1.1....................             0.4  Omni.
Applied Acoustics triple plate      Impulsive, Mobile....  0.1 to 5................  205....................             211  0.6....................               3  80.
 S[dash]Boom (700-1000 Joules) \1\.
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                                                                                         Acoustic Corers
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PanGeo (LF Chirp).................  Non-impulsive,         2 to 6.5................  177.5..................               -  4.5....................            0.06  73.
                                     stationary,
                                     intermittent.

[[Page 51122]]

 
PanGeo (HF Chirp).................  Non-impulsive,         4.5 to 12.5.............  177.5..................               -  4.5....................            0.06  73.
                                     stationary,
                                     intermittent.
Pangeo Parametric Sonar \5\.......  Non-impulsive,         90 to 115...............  239....................               -  0.25...................              40  3.5.
                                     stationary,
                                     intermittent.
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                                                                                       Positioning Systems
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Sonardyne Ranger 2--Transponder...  Non-impulsive,         19 to 34................  194....................               -  5......................               1  Omni.
                                     mobile, intermittent.
Sonardyne Ranger 2 USBL HPT 3000/5/ Non-impulsive,         19 to 34................  194....................               -  5......................               1  Not Reported.
 7000 Transceiver.                   mobile, intermittent.
Sonardyne Scout Pro Transponder...  Non-impulsive,         35 to 50................  188....................               -  5......................               3  Not Reported.
                                     mobile, intermittent.
IxSea GAPS Beacon System..........  Non-impulsive,         8-16....................  188....................  ..............  12.....................               1  Omni.
                                     mobile, intermittent.
Easytrak Nexus 2 USBL Transceiver.  Non-impulsive,         18 to 32................  192....................  ..............  5......................               2  Omni.
                                     mobile, intermittent.
Kongsberg HiPAP 501/502 USBL        Non-impulsive,         27-30.5.................  190....................  ..............  2......................               1  15.
 Tranceiver.                         mobile, intermittent.
EdgeTech BATS II Transponder......  Non-impulsive,         17 to 30................  Not Reported...........  ..............  5......................               3  Not Reported.
                                     mobile, intermittent.
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                                                                           Multi-beam Echosounders and Side Scan Sonar
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Reson SeaBat 7125 Multibeam         Non-impulsive,         200 or 400..............  220....................               -  0.03 to 0.3............               -  -
 Echosounder.                        mobile, intermittent.
RESON 700.........................  Non-impulsive,         200 or 400..............  162....................               -  0.33...................               -  -
                                     mobile, intermittent.
R2SONIC...........................  Non-impulsive,         200 or 400..............  162....................               -  0.11...................               -  -
                                     mobile, intermittent.
Klein 3900 SSS....................  Non-impulsive,         >445 kHz................  242....................               -  0.025..................               -  -
                                     mobile, intermittent.
EdgeTech 4000 & 4125 SSS..........  Non-impulsive,         410 kHz.................  225....................               -  10.....................               -  -
                                     mobile, intermittent.
EdgeTech 4200 SSS.................  Non-impulsive,         >300 kHz................  215....................               -  0.025..................               -  -
                                     mobile, intermittent.
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- = not applicable or reportable; dB re 1 [micro]Pa m = decibel reference to 1 micropascal meter; GAPS = Global Acoustic Positioning System; HF = high-frequency; LF = low-frequency; omni =
  omnidirectional source; SL = source level; SLpk = peak source level (expressed as dB re 1 [micro]Pa m); SLrms = root-mean-square source level (expressed as dB re 1 [micro]Pa m); SSS = side
  scan sonar; USBL = ultra-short baseline.
\4\ 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 700J measurements but not in
  the 1000J measurements. The CSP-N source was measured for both 700J and 1000J operations but resulted in a lower source levels; therefore the single maximum source level value was used for
  both operational levels of the S-boom.
\5\ The Pangeo acoustic corer parametric sonar was scanned out of further analysis due to high frequency content, operational beam width of less than eight degrees, and stationary operational
  position of less than 3.5 m above the seabed (Pangeo, 2018).

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

[[Page 51123]]

equipment would have the potential to result in harassment of marine 
mammals. HRG equipment that would be operated either at frequency 
ranges that fall outside the functional hearing ranges of marine 
mammals (e.g., above 180 kHz) or that operate within marine mammal 
functional hearing ranges but have low sound source levels (e.g., a 
single pulse at less than 200 dB re re 1 [mu]Pa) were assumed to not 
have the potential to result in marine mammal harassment and were 
therefore eliminated from further analysis.
    Of the potential HRG survey equipment planned for use, NMFS 
determined the following equipment does not have the potential to 
result in harassment of marine mammals:
     Multibeam echosounders and side-scan sonars: All of the 
multibeam echosounders and side-scan sonars proposed for use by 
Skipjack have operating frequencies above 180 kHz. Because these 
sources operate at frequencies that are outside the functional hearing 
ranges of all marine mammals, NMFS considers the potential for this 
equipment to result in the take of marine mammals is to be so unlikely 
as to be discountable; and
     Unlike the other HRG sources which are mobile sources, 
acoustic corers are stationary and made up of three distinct sound 
sources comprised of high frequency parametric sonar, a high frequency 
chirp sonar, and a low frequency chirp sonar; with each source having 
its own transducer. The corer is seabed-mounted while the parametric 
sonar is operated roughly 3.5 m (11.5 ft) above the seabed with the 
transducer pointed directly downwards toward the seafloor. The beam 
width of the parametric sonar is very narrow (3.5[deg]-8[deg]), 
resulting in nominal horizontal propagation. Due to the fact that these 
sources are stationary, are operated very close to the seafloor, and 
have very narrow beam widths, NMFS considers the potential for this 
equipment to result in the take of marine mammals is to be so unlikely 
as to be discountable.
    As the HRG survey equipment listed above was determined to not have 
the potential to result in the harassment of marine mammals, these 
equipment types are therefore not analyzed further in this document. 
All other HRG equipment types planned for use by Skipjack as shown in 
Table 1 are expected to have the potential to result in the harassment 
of marine mammals and are therefore carried forward in the analysis.
    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 Activity

    Sections 3 and 4 of the IHA application summarize available 
information regarding status and trends, distribution and habitat 
preferences, and behavior and life history, of the potentially affected 
species. Additional information regarding population trends and threats 
may be found in NMFS' Stock Assessment Reports (SARs; 
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' 
website (www.fisheries.noaa.gov/find-species). All species that could 
potentially occur in the proposed survey areas are included in Table 6 
of the IHA application. However, the temporal and/or spatial occurrence 
of several species listed in Table 6 of the IHA application is such 
that take of these species is not expected to occur because they have 
very low densities in the project area and/or are expected to occur 
further offshore than the proposed survey area. These are: The blue 
whale (Balaenoptera musculus), Bryde's whale (Balaenoptera edeni), 
Cuvier's beaked whale (Ziphius cavirostris), four species of 
Mesoplodont beaked whale (Mesoplodon spp.), dwarf and pygmy sperm whale 
(Kogia sima and Kogia breviceps), northern bottlenose whale (Hyperoodon 
ampullatus), pygmy killer whale (Feresa attenuata), false killer whale 
(Pseudorca crassidens), melon-headed whale (Peponocephala electra), 
striped dolphin (Stenella coeruleoalba), white-beaked dolphin 
(Lagenorhynchus albirostris), pantropical spotted dolphin (Stenella 
attenuata), Fraser's dolphin (Lagenodelphis hosei), rough-toothed 
dolphin (Steno bredanensis), Clymene dolphin (Stenella clymene), 
spinner dolphin (Stenella longirostris), hooded seal (Cystophora 
cristata), and harp seal (Pagophilus groenlandicus). As take of these 
species is not anticipated as a result of the proposed activities, 
these species are not analyzed further in this document.
    Table 2 summarizes information related to the population or stock, 
including regulatory status under the MMPA and ESA and potential 
biological removal (PBR), where known. For taxonomy, we follow 
Committee on Taxonomy (2018). PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population (as described in NMFS' 
SARs). While no mortality is anticipated or authorized here, PBR is 
included here as a gross indicator of the status of the species and 
other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Atlantic SARs. All values presented in Table 2 are the most 
recent available at the time of publication and are available in the 
2018 Atlantic SARs (Hayes et al., 2019), available online at: 
www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region.

                     Table 2--Marine Mammals Known To Occur in the Survey Area That May Be Affected by Skipjack's Proposed Activity
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      Stock abundance
                                                      MMPA and ESA    (CV, Nmin, most       Predicted                                       Expected
 Common name (scientific name)          Stock           status;      recent abundance     abundance (CV)      PBR \4\     Annual M/SI    occurrence in
                                                     strategic (Y/      survey) \2\            \3\                            \4\         survey area
                                                         N) \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                               Toothed whales (Odontoceti)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Sperm whale (Physeter            North Atlantic....  E; Y           2,288 (0.28;        5,353 (0.12).....  3.6           0.8           Rare.
 macrocephalus).                                                     1,815; n/a).
Killer whale (Orcinus orca)....  W. North Atlantic.  -; N           Unknown (n/a; n/a;  11 (0.82)........  Undet.        0             Rare.
                                                                     n/a).

[[Page 51124]]

 
Long-finned pilot whale          W. North Atlantic.  -; N           5,636 (0.63;        18,977 (0.11) \5\  35            27            Uncommon.
 (Globicephala melas).                                               3,464; n/a).
Short-finned pilot whale         W. North Atlantic.  -; N           28,924 (0.24;       18,977 (0.11) \5\  236           168           Rare.
 (Globicephala macrorhynchus).                                       23,637; n/a).
Atlantic white-sided dolphin     W. North Atlantic.  -; N           48,819 (0.61;       37,180 (0.07)....  304           30            Common.
 (Lagenorhynchus acutus).                                            30,403; n/a).
Atlantic spotted dolphin         W. North Atlantic.  -; N           44,715 (0.43;       55,436 (0.32)....  316           0             Common.
 (Stenella frontalis).                                               31,610;.
Bottlenose dolphin (Tursiops     W. North Atlantic   -; N           6,639 (0.41;        97,476 (0.06) \5\  48            unknown       Common.
 truncatus).                      Coastal Migratory.                 4,759; 2015).
Common dolphin \6\ (Delphinus    W. North Atlantic.  -; N           173,486 (0.55;      86,098 (0.12)....  557           406           Common.
 delphis).                                                           55,690; 2011).
Risso's dolphin (Grampus         W. North Atlantic.  -; N           18,250 (0.46;       7,732 (0.09).....  126           49.9          Rare.
 griseus).                                                           12,619; 2011).
Harbor porpoise (Phocoena        Gulf of Maine/Bay   -; N           79,833 (0.32;       45,089 (0.12) *..  706           255           Common.
 phocoena).                       of Fundy.                          61,415; 2011).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                Baleen whales (Mysticeti)
--------------------------------------------------------------------------------------------------------------------------------------------------------
North Atlantic right whale       W. North Atlantic.  E; Y           451 (0; 455; n/a).  411 (n/a) \7\....  0.9           56            Year round in
 (Eubalaena glacialis).                                                                                                                 continental
                                                                                                                                        shelf and slope
                                                                                                                                        waters, occur
                                                                                                                                        seasonally.
Humpback whale \8\ (Megaptera    Gulf of Maine.....  -; N           896 (0.42; 239; n/  1,637 (0.07) *...  14.6          9.8           Common year
 novaeangliae).                                                      a).                                                                round.
Fin whale \6\ (Balaenoptera      W. North Atlantic.  E; Y           3,522 (0.27;        4,633 (0.08).....  2.5           2.5           Year round in
 physalus).                                                          1,234; n/a).                                                       continental
                                                                                                                                        shelf and slope
                                                                                                                                        waters, occur
                                                                                                                                        seasonally.
Sei whale (Balaenoptera          Nova Scotia.......  E; Y           357 (0.52; 236; n/  717 (0.30) *.....  0.5           0.6           Year round in
 borealis).                                                          a).                                                                continental
                                                                                                                                        shelf and slope
                                                                                                                                        waters, occur
                                                                                                                                        seasonally.
Minke whale \6\ (Balaenoptera    Canadian East       -; N           20,741 (0.3;        2,112 (0.05) *...  14            7.5           Year round in
 acutorostrata).                  Coast.                             1,425; n/a).                                                       continental
                                                                                                                                        shelf and slope
                                                                                                                                        waters, occur
                                                                                                                                        seasonally.
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                Earless seals (Phocidae)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Gray seal \8\ (Halichoerus       W. North Atlantic.  -; N           27,131 (0.10;       505,000 (n/a)....  1,389         5,688         Uncommon.
 grypus).                                                            25,908; n/a).
Harbor seal (Phoca vitulina)...  W. North Atlantic.  -; N           75,834 (0.15;       75,834 (0.15)....  2,006         345           Uncommon.
                                                                     66,884; 2012).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\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 (see
  footnote 3) or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ Stock abundance as reported in NMFS marine mammal stock assessment reports (SAR) except where otherwise noted. SARs available online at:
  www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments. CV is coefficient of variation; Nmin is the minimum estimate
  of stock abundance. In some cases, CV is not applicable. For certain stocks, abundance estimates are actual counts of animals and there is no
  associated CV. The most recent abundance survey that is reflected in the abundance estimate is presented; there may be more recent surveys that have
  not yet been incorporated into the estimate. All values presented here are from the 2018 draft Atlantic SARs.
\3\ This information represents species- or guild-specific abundance predicted by recent habitat-based cetacean density models (Roberts et al., 2016,
  2017, 2018) (with the exception of North Atlantic right whales and pinnipeds--see footnotes 7 and 9 below). These models provide the best available
  scientific information regarding predicted density patterns of cetaceans in the U.S. Atlantic Ocean, and we provide the corresponding abundance
  predictions as a point of reference. Total abundance estimates were produced by computing the mean density of all pixels in the modeled area and
  multiplying by its area. For those species marked with an asterisk (*), the available information supported development of either two or four seasonal
  models; each model has an associated abundance prediction. Here, we report the maximum predicted abundance.
\4\ Potential biological removal, defined by the MMPA as the maximum number of animals, not including natural mortalities, that may be removed from a
  marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population size (OSP). Annual M/SI, found in NMFS' SARs,
  represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, subsistence hunting, ship
  strike). Annual M/SI values often cannot be determined precisely and is in some cases presented as a minimum value. All M/SI values are as presented
  in the draft 2018 SARs.
\5\ Abundance estimates are in some cases reported for a guild or group of species when those species are difficult to differentiate at sea. Similarly,
  the habitat-based cetacean density models produced by Roberts et al. (2016, 2017, 2018) are based in part on available observational data which, in
  some cases, is limited to genus or guild in terms of taxonomic definition. Roberts et al. (2016, 2017, 2018) produced density models to genus level
  for Globicephala spp. produced density models for bottlenose dolphins that do not differentiate between offshore and coastal stocks, and produced
  density models for all seals.
\6\ Abundance as reported in the 2007 Canadian Trans-North Atlantic Sighting Survey (TNASS), which provided full coverage of the Atlantic Canadian coast
  (Lawson and Gosselin, 2009). Abundance estimates from TNASS were corrected for perception and availability bias, when possible. In general, where the
  TNASS survey effort provided superior coverage of a stock's range (as compared with NOAA shipboard survey effort), the resulting abundance estimate is
  considered more accurate than the current NMFS abundance estimate (derived from survey effort with inferior coverage of the stock range). NMFS SAR
  reports the stock abundance estimate for the common dolphin as 70,184; NMFS SAR reports the stock abundance estimate for the fin whale as 1,618; NMFS
  SAR reports the stock abundance estimate for the minke whale as 2,591.
\7\ For the North Atlantic right whale the best available abundance estimate is derived from the 2018 North Atlantic Right Whale Consortium 2018 Annual
  Report Card (Pettis et al., 2018).
\8\ 2018 U.S. Atlantic draft SAR for the Gulf of Maine feeding population lists a current abundance estimate of 896 individuals. However, we note that
  the estimate is defined on the basis of feeding location alone (i.e., Gulf of Maine) and is therefore likely an underestimate.
\9\ The NMFS stock abundance estimate applies to U.S. population only, however the actual stock abundance is approximately 505,000.


[[Page 51125]]

    Four marine mammal species that are listed under the Endangered 
Species Act (ESA) may be present in the survey area and are included in 
the take request: The North Atlantic right whale, fin whale, sei whale, 
and sperm whale.
    Below is a description of the species that are both common in the 
survey area offshore of Delaware and Maryland that have the highest 
likelihood of occurring, at least seasonally, in the survey area and 
are thus are expected to potentially be taken by the proposed 
activities. For the majority of species potentially present in the 
specific geographic region, NMFS has designated only a single generic 
stock (e.g., ``western North Atlantic'') for management purposes. This 
includes the ``Canadian east coast'' stock of minke whales, which 
includes all minke whales found in U.S. waters. For humpback and sei 
whales, NMFS defines stocks on the basis of feeding locations, i.e., 
Gulf of Maine and Nova Scotia, respectively. However, our reference to 
humpback whales and sei whales in this document refers to any 
individuals of the species that are found in the specific geographic 
region.

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., 2018). Surveys have demonstrated 
the existence of seven areas where North Atlantic right whales 
congregate seasonally, including north and east of the proposed project 
area in Georges Bank, off Cape Cod, and in Massachusetts Bay (Hayes et 
al., 2018). In the late fall months (e.g. October), right whales are 
generally thought to depart from the feeding grounds in the North 
Atlantic and move south to their calving grounds off Georgia and 
Florida. However, recent research indicates our understanding of their 
movement patterns remains incomplete (Davis et al. 2017). A review of 
passive acoustic monitoring data from 2004 to 2014 throughout the 
western North Atlantic demonstrated nearly continuous year-round right 
whale presence across their entire habitat range (for at least some 
individuals), including in locations previously thought of as migratory 
corridors, suggesting that not all of the population undergoes a 
consistent annual migration (Davis et al. 2017). Movements within and 
between habitats are extensive, and the area offshore from the Mid-
Atlantic states is an important migratory corridor (Waring et al., 
2016). The project area is not a known feeding area for right whales 
and right whales are not expected to be foraging there. Therefore, any 
right whales in the vicinity of the project area are expected to be 
transient, most likely migrating through the area.
    The western North Atlantic population demonstrated overall growth 
of 2.8 percent per year between 1990 to 2010, despite a decline in 1993 
and no growth between 1997 and 2000 (Pace et al. 2017). However, since 
2010 the population has been in decline, with a 99.99 percent 
probability of a decline of just under 1 percent per year (Pace et al. 
2017). Between 1990 and 2015, calving rates varied substantially, with 
low calving rates coinciding with all three periods of decline or no 
growth (Pace et al. 2017). On average, North Atlantic right whale 
calving rates are estimated to be roughly half that of southern right 
whales (Eubalaena australis) (Pace et al. 2017), which are increasing 
in abundance (NMFS 2015). In 2018, no new North Atlantic right whale 
calves were documented in their calving grounds; this represented the 
first time since annual NOAA aerial surveys began in 1989 that no new 
right whale calves were observed. Seven right whale calves were 
documented in 2019. The current best estimate of population abundance 
for the species is 411 individuals (Pettis et al., 2018).
    Elevated North Atlantic right whale mortalities have occurred since 
June 7, 2017 along the U.S. and Canadian coast. A total of 29 confirmed 
dead stranded whales (20 in Canada; 9 in the United States) have been 
documented. This event has been declared an Unusual Mortality Event 
(UME), with human interactions, including entanglement in fixed fishing 
gear and vessel strikes, implicated in at least 13 of the mortalities 
thus far. More information is available online at: 
www.fisheries.noaa.gov/national/marine-life-distress/2017-2019-north-atlantic-right-whale-unusual-mortality-event.
    The proposed survey area is part of an important migratory area for 
North Atlantic right whales; this important migratory area is comprised 
of the waters of the continental shelf offshore the East Coast of the 
United States and extends from Florida through Massachusetts. NMFS' 
regulations at 50 CFR part 224.105 designated nearshore waters of the 
Mid-Atlantic Bight as Mid-Atlantic U.S. Seasonal Management Areas (SMA) 
for right whales in 2008. SMAs were developed to reduce the threat of 
collisions between ships and right whales around their migratory route 
and calving grounds. 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.
    A key question with regard to humpback whales off the mid-Atlantic 
states is their stock identity. Using fluke photographs of living and 
dead whales observed in the region, Barco et al. (2002) reported that 
43 percent of 21 live whales matched to the Gulf of Maine, 19 percent 
to Newfoundland, and 4.8 percent to the Gulf of St. Lawrence, while 
31.6 percent of 19 dead humpbacks were known Gulf of Maine whales. 
Although the population composition of the mid-Atlantic is apparently 
dominated by Gulf of Maine whales, lack of photographic effort in 
Newfoundland makes it likely that the observed match rates under-
represent the true presence of Canadian whales in the region (Waring et 
al., 2016). Barco et al. (2002) suggested that the mid-Atlantic region 
primarily represents a supplemental winter feeding ground used by 
humpbacks.
    Since January 2016, elevated humpback whale mortalities have 
occurred along the Atlantic coast from Maine to Florida. Partial or 
full necropsy examinations have been conducted on approximately half of 
the 103 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

[[Page 51126]]

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/2016-2019-humpback-whale-unusual-mortality-event-along-atlantic-coast.

Fin Whale

    Fin whales are common in waters of the U.S. Atlantic Exclusive 
Economic Zone (EEZ), principally from Cape Hatteras northward (Waring 
et al., 2016). Fin whales are present 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 (Waring 
et al., 2016). 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 (Waring et al., 2016).

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. The southern portion of the 
stock's range during spring and summer includes the Gulf of Maine and 
Georges Bank. Spring is the period of greatest abundance in U.S. 
waters, with sightings concentrated along the eastern margin of Georges 
Bank and into the Northeast Channel area, and along the southwestern 
edge of Georges Bank in the area of Hydrographer Canyon (Waring et al., 
2015). 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.

Minke Whale

    Minke whales can be found in temperate, tropical, and high-latitude 
waters. The Canadian East Coast stock can be found in the area from the 
western half of the Davis Strait (45[deg] W) to the Gulf of Mexico 
(Waring et al., 2016). This species generally occupies waters less than 
100 m deep on the continental shelf. Little is known about minke 
whales' specific movements through the mid-Atlantic region; however, 
there appears to be a strong seasonal component to minke whale 
distribution, with acoustic detections indicating that they migrate 
south in mid-October to early November, and return from wintering 
grounds starting in March through early April (Risch et al., 2014). 
Northward migration appears to track the warmer waters of the Gulf 
Stream along the continental shelf, while southward migration is made 
farther offshore (Risch et al., 2014).
    Since January 2017, elevated minke whale mortalities have occurred 
along the Atlantic coast from Maine through South Carolina, with a 
total of 66 strandings recorded through August 30, 2019. 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/2017-2019-minke-whale-unusual-mortality-event-along-atlantic-coast.

Sperm Whale

    The distribution of the sperm whale in the U.S. EEZ occurs on the 
continental shelf edge, over the continental slope, and into mid-ocean 
regions (Waring et al., 2014). The basic social unit of the sperm whale 
appears to be the mixed school of adult females plus their calves and 
some juveniles of both sexes, normally numbering 20-40 animals in all. 
There is evidence that some social bonds persist for many years 
(Christal et al., 1998). This species forms stable social groups, site 
fidelity, and latitudinal range limitations in groups of females and 
juveniles (Whitehead, 2002). In winter, sperm whales concentrate east 
and northeast of Cape Hatteras. In spring, distribution shifts 
northward to east of Delaware and Virginia, and is widespread 
throughout the central Mid-Atlantic Bight and the southern part of 
Georges Bank. In the fall, sperm whale occurrence on the continental 
shelf south of New England reaches peak levels, and there remains a 
continental shelf edge occurrence in the Mid-Atlantic Bight (Waring et 
al., 2015).

Long-Finned Pilot Whale

    Long-finned pilot whales are found from North Carolina and north to 
Iceland, Greenland and the Barents Sea (Waring et al., 2016). 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 (Waring et al., 2016). Long-finned and short-
finned pilot whales overlap spatially along the mid-Atlantic shelf 
break between New Jersey and the southern flank of Georges Bank (Payne 
and Heinemann 1993; Rone and Pace 2012). 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., 2019). 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 (Waring et al., 2016).

Short-Finned Pilot Whale

    As described above, long-finned and short-finned pilot whales 
overlap spatially along the mid-Atlantic shelf break between New Jersey 
and the southern flank of Georges Bank (Payne and Heinemann 1993; Rone 
and Pace 2012). 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., 2019). In addition, short-finned 
pilot whales are documented along the continental shelf and continental 
slope in the northern Gulf of Mexico (Hansen et al. 1996; Mullin and 
Hoggard 2000; 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 (Waring et al., 2016).

Killer Whale

    Killer whale distribution in the Atlantic extends from the Arctic 
ice edge to the West Indies. They are normally found in small groups, 
although 40 animals were reported from the southern Gulf of Maine in 
September 1979, and 29 animals in Massachusetts Bay in August 1986 
(Katona et al., 1988). In the U.S. Atlantic EEZ, while their occurrence 
is unpredictable, they do occur in fishing areas, perhaps coincident 
with tuna, in warm seasons (Katona et al., 1988; NMFS unpublished 
data). Killer whales are characterized as uncommon or rare

[[Page 51127]]

in waters of the U.S. Atlantic EEZ (Katona et al. 1988). Sightings 
within the survey area would be considered very rare; however, due to 
their wide-ranging habits and a uniform habitat density within the 
entire U.S. Atlantic coast, there is the potential for killer whales to 
be present during the proposed surveys.

Atlantic White-Sided Dolphin

    White-sided dolphins are found in temperate and sub-polar waters of 
the North Atlantic, primarily in continental shelf waters to the 100-m 
depth contour from central West Greenland to North Carolina (Waring et 
al., 2016). 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 (Waring et al., 2014). This stock regularly 
occurs in continental shelf waters south of Cape Hatteras and in 
continental shelf edge and continental slope waters north of this 
region (Waring et al., 2014). There are two forms of this species, with 
the larger ecotype inhabiting the continental shelf and is usually 
found inside or near the 200 m isobaths (Waring et al., 2014).

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 
(Waring et al., 2016). 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., 2019; Hamazaki, 2002; Selzer and Payne, 1988).

Bottlenose Dolphin

    There are two distinct bottlenose dolphin morphotypes in the 
western North Atlantic: The coastal and offshore forms (Waring et al., 
2016). 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 (Waring et al., 2014). 
During summer months (July-August), this stock occupies coastal waters 
from the shoreline to approximately the 25-m isobath between the mouth 
of the Chesapeake Bay and Long Island, New York; during winter months 
(January-March), the stock occupies coastal waters from Cape Lookout, 
North Carolina, to the North Carolina/Virginia border (Waring et al., 
2014). As the offshore stock is primarily found in waters greater than 
40 m, while the migratory stock is primarily found in waters less than 
25 m, we expect that any bottlenose dolphins encountered by the 
proposed survey would be from the Western North Atlantic northern 
migratory coastal stock, as the mean water depth of the wind farm lease 
area is 28 m and maximum water depth in the cable route corridor survey 
areas is 28 m.

Harbor Porpoise

    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 (Waring et al., 2016). 
They are seen from the coastline to deep waters (>1800 m; Westgate et 
al. 1998), although the majority of the population is found over the 
continental shelf (Waring et al., 2016). 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 (Waring et 
al., 2016).

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., 2018). The harbor seals within the Project Area are part 
of the single Western North Atlantic stock. 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/2018-2019-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 (Waring et al., 
2016). 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 (Waring et al., 2016). It is

[[Page 51128]]

believed that recolonization by Canadian gray seals is the source of 
the U.S. population (Waring et al., 2016). 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/2018-2019-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, 2019) 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; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information. 
Seventeen marine mammal species (15 cetacean and 2 pinniped (both 
phocid species)) have the reasonable potential to co-occur with the 
proposed activities. Please refer to Table 2. Of the cetacean species 
that may be present, five are classified as low-frequency cetaceans 
(i.e., all mysticete species), nine are classified as mid-frequency 
cetaceans (i.e., sperm whale and all delphinid species), 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.

Description of Sound Sources

    This section contains a brief technical background on sound, on the 
characteristics of certain sound types, and on metrics used in this 
proposal inasmuch as the information is relevant to the specified 
activity and to a discussion of the potential effects of the specified 
activity on marine mammals found later in this document. For general 
information on sound and its interaction with the marine environment, 
please see, e.g., Au and Hastings (2008); Richardson et al. (1995); 
Urick (1983).
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in hertz (Hz) or cycles per second. Wavelength is the 
distance between two peaks or corresponding points of a sound wave 
(length of one cycle). Higher frequency sounds have shorter wavelengths 
than lower frequency sounds, and typically attenuate (decrease) more 
rapidly, except in certain cases in shallower water. Amplitude is the 
height of the sound pressure wave or the ``loudness'' of a sound and is 
typically described using the relative unit of the decibel (dB). A 
sound pressure level (SPL) in dB is described as the ratio between a 
measured pressure and a reference pressure (for underwater sound, this 
is 1 microPascal ([mu]Pa)), and is a logarithmic unit that accounts for 
large variations in amplitude; therefore, a relatively small change in 
dB corresponds to large changes in sound pressure. The source level 
(SL) represents the SPL referenced at a distance of 1 m from the source 
(referenced to 1 [mu]Pa), while the received level is the SPL at the 
listener's position (referenced to 1 [mu]Pa).
    Root mean square (rms) is the quadratic mean sound pressure over 
the duration of an impulse. Root mean square is calculated by squaring 
all of the sound amplitudes, averaging the squares, and then taking the 
square root of the average (Urick, 1983). Root mean square accounts for 
both positive and negative values; squaring the pressures makes all 
values positive so that they

[[Page 51129]]

may be accounted for in the summation of pressure levels (Hastings and 
Popper, 2005). This measurement is often used in the context of 
discussing behavioral effects, in part because behavioral effects, 
which often result from auditory cues, may be better expressed through 
averaged units than by peak pressures.
    Sound exposure level (SEL; represented as dB re 1 [mu]Pa\2\-s) 
represents the total energy in a stated frequency band over a stated 
time interval or event, and considers both intensity and duration of 
exposure. The per-pulse SEL is calculated over the time window 
containing the entire pulse (i.e., 100 percent of the acoustic energy). 
SEL is a cumulative metric; it can be accumulated over a single pulse, 
or calculated over periods containing multiple pulses. Cumulative SEL 
represents the total energy accumulated by a receiver over a defined 
time window or during an event. Peak sound pressure (also referred to 
as zero-to-peak sound pressure or 0-pk) is the maximum instantaneous 
sound pressure measurable in the water at a specified distance from the 
source, and is represented in the same units as the rms sound pressure.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in a 
manner similar to ripples on the surface of a pond and may be either 
directed in a beam or beams or may radiate in all directions 
(omnidirectional sources). The compressions and decompressions 
associated with sound waves are detected as changes in pressure by 
aquatic life and man-made sound receptors such as hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound, which is 
defined as environmental background sound levels lacking a single 
source or point (Richardson et al., 1995). The sound level of a region 
is defined by the total acoustical energy being generated by known and 
unknown sources. These sources may include physical (e.g., wind and 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
(e.g., vessels, dredging, construction) sound. A number of sources 
contribute to ambient sound, including wind and waves, which are a main 
source of naturally occurring ambient sound for frequencies between 200 
hertz (Hz) and 50 kilohertz (kHz) (Mitson, 1995). In general, ambient 
sound levels tend to increase with increasing wind speed and wave 
height. Precipitation can become an important component of total sound 
at frequencies above 500 Hz, and possibly down to 100 Hz during quiet 
times. Marine mammals can contribute significantly to ambient sound 
levels, as can some fish and snapping shrimp. The frequency band for 
biological contributions is from approximately 12 Hz to over 100 kHz. 
Sources of ambient sound related to human activity include 
transportation (surface vessels), dredging and construction, oil and 
gas drilling and production, geophysical surveys, sonar, and 
explosions. Vessel noise typically dominates the total ambient sound 
for frequencies between 20 and 300 Hz. In general, the frequencies of 
anthropogenic sounds are below 1 kHz and, if higher frequency sound 
levels are created, they attenuate rapidly.
    The sum of the various natural and anthropogenic sound sources that 
comprise ambient sound at any given location and time depends not only 
on the source levels (as determined by current weather conditions and 
levels of biological and human activity) but also on the ability of 
sound to propagate through the environment. In turn, sound propagation 
is dependent on the spatially and temporally varying properties of the 
water column and sea floor, and is frequency-dependent. As a result of 
the dependence on a large number of varying factors, ambient sound 
levels can be expected to vary widely over both coarse and fine spatial 
and temporal scales. Sound levels at a given frequency and location can 
vary by 10-20 decibels (dB) from day to day (Richardson et al., 1995). 
The result is that, depending on the source type and its intensity, 
sound from the specified activity may be a negligible addition to the 
local environment or could form a distinctive signal that may affect 
marine mammals.
    Sounds are often considered to fall into one of two general types: 
pulsed and non-pulsed. The distinction between these two sound types is 
important because they have differing potential to cause physical 
effects, particularly with regard to hearing (e.g., Ward, 1997 in 
Southall et al., 2007). Please see Southall et al. (2007) for an in-
depth discussion of these concepts. The distinction between these two 
sound types is not always obvious, as certain signals share properties 
of both pulsed and non-pulsed sounds. A signal near a source could be 
categorized as a pulse, but due to propagation effects as it moves 
farther from the source, the signal duration becomes longer (e.g., 
Greene and Richardson, 1988).
    Pulsed sound sources (e.g., airguns, explosions, gunshots, sonic 
booms, impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI, 1986, 2005; Harris, 1998; NIOSH, 1998; ISO, 2003) and occur 
either as isolated events or repeated in some succession. Pulsed sounds 
are all characterized by a relatively rapid rise from ambient pressure 
to a maximal pressure value followed by a rapid decay period that may 
include a period of diminishing, oscillating maximal and minimal 
pressures, and generally have an increased capacity to induce physical 
injury as compared with sounds that lack these features.
    Non-pulsed sounds can be tonal, narrowband, or broadband, brief or 
prolonged, and may be either continuous or intermittent (ANSI, 1995; 
NIOSH, 1998). Some of these non-pulsed sounds can be transient signals 
of short duration but without the essential properties of pulses (e.g., 
rapid rise time). Examples of non-pulsed sounds include those produced 
by vessels, aircraft, machinery operations such as drilling or 
dredging, vibratory pile driving, and active sonar systems. The 
duration of such sounds, as received at a distance, can be greatly 
extended in a highly reverberant environment.
    Potential Effects of Underwater Sound--Note that, in the following 
discussion, we refer in many cases to a review article concerning 
studies of noise-induced hearing loss conducted from 1996-2015 (i.e., 
Finneran, 2015). For study-specific citations, please see that work. 
Anthropogenic sounds cover a broad range of frequencies and sound 
levels and can have a range of highly variable impacts on marine life, 
from none or minor to potentially severe responses, depending on 
received levels, duration of exposure, behavioral context, and various 
other factors. The potential effects of underwater sound from active 
acoustic sources can potentially result in one or more of the 
following: Temporary or permanent hearing impairment, non-auditory 
physical or physiological effects, behavioral disturbance, stress, and 
masking (Richardson et al., 1995; Gordon et al., 2004; Nowacek et al., 
2007; Southall et al., 2007; G[ouml]tz et al., 2009). The degree of 
effect is intrinsically related to the signal characteristics, received 
level, distance from the source, and duration of the sound exposure. In 
general, sudden, high level sounds can cause hearing loss, as can 
longer exposures to lower level sounds. Temporary or permanent

[[Page 51130]]

loss of hearing will occur almost exclusively for noise within an 
animal's hearing range.
    Richardson et al. (1995) described zones of increasing intensity of 
effect that might be expected to occur, in relation to distance from a 
source and assuming that the signal is within an animal's hearing 
range. First is the area within which the acoustic signal would be 
audible (potentially perceived) to the animal but not strong enough to 
elicit any overt behavioral or physiological response. The next zone 
corresponds with the area where the signal is audible to the animal and 
of sufficient intensity to elicit behavioral or physiological 
responsiveness. Third is a zone within which, for signals of high 
intensity, the received level is sufficient to potentially cause 
discomfort or tissue damage to auditory or other systems. Overlaying 
these zones to a certain extent is the area within which masking (i.e., 
when a sound interferes with or masks the ability of an animal to 
detect a signal of interest that is above the absolute hearing 
threshold) may occur; the masking zone may be highly variable in size.
    We describe the more severe effects (i.e., certain non-auditory 
physical or physiological effects) only briefly as we do not expect 
that there is a reasonable likelihood that HRG surveys may result in 
such effects (see below for further discussion). Potential effects from 
impulsive sound sources can range in severity from effects such as 
behavioral disturbance or tactile perception to physical discomfort, 
slight injury of the internal organs and the auditory system, or 
mortality (Yelverton et al., 1973). Non-auditory physiological effects 
or injuries that theoretically might occur in marine mammals exposed to 
high level underwater sound or as a secondary effect of extreme 
behavioral reactions (e.g., change in dive profile as a result of an 
avoidance reaction) caused by exposure to sound include neurological 
effects, bubble formation, resonance effects, and other types of organ 
or tissue damage (Cox et al., 2006; Southall et al., 2007; Zimmer and 
Tyack, 2007; Tal et al., 2015). The activities considered here do not 
involve the use of devices such as explosives or mid-frequency tactical 
sonar that are associated with these types of effects.
    Threshold Shift--Marine mammals exposed to high-intensity sound, or 
to lower-intensity sound for prolonged periods, can experience hearing 
threshold shift (TS), which is the loss of hearing sensitivity at 
certain frequency ranges (Finneran, 2015). TS can be permanent (PTS), 
in which case the loss of hearing sensitivity is not fully recoverable, 
or temporary (TTS), in which case the animal's hearing threshold would 
recover over time (Southall et al., 2007). Repeated sound exposure that 
leads to TTS could cause PTS. In severe cases of PTS, there can be 
total or partial deafness, while in most cases the animal has an 
impaired ability to hear sounds in specific frequency ranges (Kryter, 
1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS represents primarily tissue 
fatigue and is reversible (Southall et al., 2007). In addition, other 
investigators have suggested that TTS is within the normal bounds of 
physiological variability and tolerance and does not represent physical 
injury (e.g., Ward, 1997). Therefore, NMFS does not consider TTS to 
constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals, and there is no PTS data for cetaceans, but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above (a 40-dB threshold shift approximates PTS onset; 
e.g., Kryter et al., 1966; Miller, 1974) that inducing mild TTS (a 6-dB 
threshold shift approximates TTS onset; e.g., Southall et al. 2007). 
Based on data from terrestrial mammals, a precautionary assumption is 
that the PTS thresholds for impulse sounds (such as impact pile driving 
pulses as received close to the source) are at least 6 dB higher than 
the TTS threshold on a peak-pressure basis and PTS cumulative sound 
exposure level thresholds are 15 to 20 dB higher than TTS cumulative 
sound exposure level thresholds (Southall et al., 2007). Given the 
higher level of sound or longer exposure duration necessary to cause 
PTS as compared with TTS, it is considerably less likely that PTS could 
occur.
    TTS is the mildest form of hearing impairment that can occur during 
exposure to sound (Kryter, 1985). While experiencing TTS, the hearing 
threshold rises, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. Few data 
on sound levels and durations necessary to elicit mild TTS have been 
obtained for marine mammals.
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS, and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to 
serious. For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that occurs during a time where ambient noise is lower and there 
are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin, beluga whale (Delphinapterus leucas), harbor 
porpoise, and Yangtze finless porpoise (Neophocoena asiaeorientalis)) 
and three species of pinnipeds (northern elephant seal (Mirounga 
angustirostris), harbor seal, and California sea lion (Zalophus 
californianus)) exposed to a limited number of sound sources (i.e., 
mostly tones and octave-band noise) in laboratory settings (Finneran, 
2015). TTS was not observed in trained spotted (Phoca largha) and 
ringed (Pusa hispida) seals exposed to impulsive noise at levels 
matching previous predictions of TTS onset (Reichmuth et al., 2016). In 
general, harbor seals and harbor porpoises have a lower TTS onset than 
other measured pinniped or cetacean species (Finneran, 2015). 
Additionally, the existing marine mammal TTS data come from a limited 
number of individuals within these species. There are no data available 
on noise-induced hearing loss for mysticetes. For summaries of data on 
TTS in marine mammals or for further discussion of TTS onset 
thresholds, please see Southall et al. (2007), Finneran and Jenkins 
(2012), Finneran (2015), and NMFS (2018).
    Animals in the survey area during the proposed survey are unlikely 
to incur TTS due to the characteristics of the sound sources, which 
include relatively low source levels and generally very short pulses 
and duration of the sound. Even for high-frequency cetacean species 
(e.g., harbor porpoises), which may have increased sensitivity to TTS 
(Lucke et al., 2009; Kastelein et al., 2012b), individuals would have 
to make a very close approach and also remain very close to vessels 
operating these sources in order to receive multiple exposures at 
relatively high levels, as would be necessary to cause TTS. 
Intermittent exposures--as would occur

[[Page 51131]]

due to the brief, transient signals produced by these sources--require 
a higher cumulative SEL to induce TTS than would continuous exposures 
of the same duration (i.e., intermittent exposure results in lower 
levels of TTS) (Mooney et al., 2009a; Finneran et al., 2010). Moreover, 
most marine mammals would more likely avoid a loud sound source rather 
than swim in such close proximity as to result in TTS. Kremser et al. 
(2005) noted that the probability of a cetacean swimming through the 
area of exposure when a sub-bottom profiler emits a pulse is small--
because if the animal was in the area, it would have to pass the 
transducer at close range in order to be subjected to sound levels that 
could cause TTS and would likely exhibit avoidance behavior to the area 
near the transducer rather than swim through at such a close range. 
Further, the restricted beam shape of the majority of the geophysical 
survey equipment planned for use makes it unlikely that an animal would 
be exposed more than briefly during the passage of the vessel.
    Behavioral Effects--Behavioral disturbance may include a variety of 
effects, including subtle changes in behavior (e.g., minor or brief 
avoidance of an area or changes in vocalizations), more conspicuous 
changes in similar behavioral activities, and more sustained and/or 
potentially severe reactions, such as displacement from or abandonment 
of high-quality habitat. Behavioral responses to sound are highly 
variable and context-specific and any reactions depend on numerous 
intrinsic and extrinsic factors (e.g., species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day), as well as the interplay between factors (e.g., 
Richardson et al., 1995; Wartzok et al., 2003; Southall et al., 2007; 
Weilgart, 2007; Archer et al., 2010). Behavioral reactions can vary not 
only among individuals but also within an individual, depending on 
previous experience with a sound source, context, and numerous other 
factors (Ellison et al., 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). 
Please see Appendices B-C of Southall et al. (2007) for a review of 
studies involving marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al., 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. As noted, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; NRC, 2003; Wartzok et al., 2003). Controlled experiments with 
captive marine mammals have showed pronounced behavioral reactions, 
including avoidance of loud sound sources (Ridgway et al., 1997; 
Finneran et al., 2003). Observed responses of wild marine mammals to 
loud pulsed sound sources (typically airguns or acoustic harassment 
devices) have been varied but often consist of avoidance behavior or 
other behavioral changes suggesting discomfort (Morton and Symonds, 
2002; see also Richardson et al., 1995; Nowacek et al., 2007). However, 
many delphinids approach low-frequency airgun source vessels with no 
apparent discomfort or obvious behavioral change (e.g., Barkaszi et 
al., 2012), indicating the importance of frequency output in relation 
to the species' hearing sensitivity.
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al.; 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior 
may reflect interruptions in biologically significant activities (e.g., 
foraging) or they may be of little biological significance. The impact 
of an alteration to dive behavior resulting from an acoustic exposure 
depends on what the animal is doing at the time of the exposure and the 
type and magnitude of the response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al.; 2004; Madsen et al., 2006; Yazvenko et al., 
2007). A determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that respiration rates may 
either be unaffected or could increase, depending on the species and 
signal characteristics, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et 
al., 2007; Gailey et al., 2016).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can

[[Page 51132]]

occur for any of these modes and may result from a need to compete with 
an increase in background noise or may reflect increased vigilance or a 
startle response. For example, in the presence of potentially masking 
signals, humpback whales and killer whales have been observed to 
increase the length of their songs (Miller et al., 2000; Fristrup et 
al., 2003; Foote et al., 2004), while right whales have been observed 
to shift the frequency content of their calls upward while reducing the 
rate of calling in areas of increased anthropogenic noise (Parks et 
al., 2007). In some cases, animals may cease sound production during 
production of aversive signals (Bowles et al., 1994).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from airgun surveys (Malme et al., 
1984). Avoidance may be short-term, with animals returning to the area 
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; 
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). 
Longer-term displacement is possible, however, which may lead to 
changes in abundance or distribution patterns of the affected species 
in the affected region if habituation to the presence of the sound does 
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann 
et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996). The result of a flight response could range from 
brief, temporary exertion and displacement from the area where the 
signal provokes flight to, in extreme cases, marine mammal strandings 
(Evans and England, 2001). However, it should be noted that response to 
a perceived predator does not necessarily invoke flight (Ford and 
Reeves, 2008), and whether individuals are solitary or in groups may 
influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a five-day period did not cause any 
sleep deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    We expect that some marine mammals may exhibit behavioral responses 
to the HRG survey activities in the form of avoidance of the area 
during the activity, especially the naturally shy harbor porpoise, 
while others such as delphinids might be attracted to the survey 
activities out of curiosity. However, because the HRG survey equipment 
operates from a moving vessel, and the maximum radius to the Level B 
harassment threshold is relatively small, the area and time that this 
equipment would be affecting a given location is very small. Further, 
once an area has been surveyed, it is not likely that it will be 
surveyed again, thereby reducing the likelihood of repeated impacts 
within the survey area.
    We have also considered the potential for severe behavioral 
responses such as stranding and associated indirect injury or mortality 
from Skipjack's use of HRG survey equipment. Previous commenters have 
referenced a 2008 mass stranding of approximately 100 melon-headed 
whales in a Madagascar lagoon system. An investigation of the event 
indicated that use of a high-frequency mapping system (12-kHz multibeam 
echosounder) was the most plausible and likely initial behavioral 
trigger of the event, while providing the caveat that there is no 
unequivocal and easily identifiable single cause (Southall et al., 
2013). The investigatory panel's conclusion was based on (1) very close 
temporal and spatial association and directed movement of the survey 
with the stranding event; (2) the unusual nature of such an event 
coupled with previously documented apparent behavioral sensitivity of 
the species to other sound types (Southall et al., 2006; Brownell et 
al., 2009); and (3) the fact that all other possible factors considered 
were determined to be unlikely causes. Specifically, regarding survey 
patterns prior to the event and in relation to bathymetry, the vessel 
transited in a north-south direction on the shelf break parallel to the 
shore, ensonifying large areas of deep-water habitat prior to operating 
intermittently in a concentrated area offshore from the stranding site; 
this may have trapped the animals between the sound source and the 
shore, thus driving them towards the lagoon system. The investigatory 
panel systematically excluded or deemed highly unlikely nearly all 
potential reasons for these animals leaving their typical pelagic 
habitat for an area extremely atypical for the species (i.e., a shallow 
lagoon system). Notably, this was the first time that such a system has 
been associated with a stranding event. The panel also noted several 
site- and situation-specific secondary factors that may have 
contributed to the avoidance responses that led to the eventual 
entrapment and mortality of the whales. Specifically, shoreward-
directed surface currents and elevated chlorophyll levels in the area 
preceding the event may have played a role (Southall et al., 2013). The 
report also notes that prior use of a similar system in the general 
area may have sensitized the animals and also concluded that, for 
odontocete cetaceans that hear well in higher frequency ranges where 
ambient noise is typically quite low, high-power active sonars 
operating in this range may be

[[Page 51133]]

more easily audible and have potential effects over larger areas than 
low frequency systems that have more typically been considered in terms 
of anthropogenic noise impacts. It is, however, important to note that 
the relatively lower output frequency, higher output power, and complex 
nature of the system implicated in this event, in context of the other 
factors noted here, likely produced a fairly unusual set of 
circumstances that indicate that such events would likely remain rare 
and are not necessarily relevant to use of lower-power, higher-
frequency systems more commonly used for HRG survey applications. The 
risk of similar events recurring is likely very low, given the 
extensive use of active acoustic systems used for scientific and 
navigational purposes worldwide on a daily basis and the lack of direct 
evidence of such responses previously reported.
    Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals will experience physiological stress responses upon exposure to 
acoustic stressors and that it is possible that some of these would be 
classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003).
    NMFS does not expect that the generally short-term, intermittent, 
and transitory HRG 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.
    Auditory Masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al., 1995; Erbe et al., 
2016). Masking occurs when the receipt of a sound is interfered with by 
another coincident sound at similar frequencies and at similar or 
higher intensity, and may occur whether the sound is natural (e.g., 
snapping shrimp, wind, waves, precipitation) or anthropogenic (e.g., 
shipping, sonar, seismic exploration) in origin. The ability of a noise 
source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is man-made, it may be considered harassment 
if disrupting behavioral patterns. It is important to distinguish TTS 
and PTS, which persist after the sound exposure, from masking, which 
occurs during the sound exposure. Because masking (without resulting in 
TS) is not associated with abnormal physiological function, it is not 
considered a physiological effect, but rather a potential behavioral 
effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al., 2000; 
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2009; Holt 
et al., 2009). Masking can be reduced in situations where the signal 
and noise come from different directions (Richardson et al., 1995), 
through amplitude modulation of the signal, or through other 
compensatory behaviors (Houser and Moore, 2014). Masking can be tested 
directly in captive species (e.g., Erbe, 2008), but in wild populations 
it must be either modeled or inferred from evidence of masking 
compensation. There are few studies addressing real-world masking 
sounds likely to be experienced by marine mammals in the wild (e.g., 
Branstetter et al., 2013).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency

[[Page 51134]]

ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand, 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.
    Marine mammal communications would not likely be masked appreciably 
by the HRG equipment given the directionality of the signals (for most 
geophysical survey equipment types planned for use (Table 1)) and the 
brief period when an individual mammal is likely to be within its beam.

Vessel Strike

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

Anticipated Effects on Marine Mammal Habitat

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

[[Page 51135]]

species) in the surrounding area, any impacts to marine mammal habitat 
are not expected to result in significant or long-term consequences for 
individual marine mammals, or to contribute to adverse impacts on their 
populations. Effects to habitat will not be discussed further in this 
document.

Estimated Take

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

Acoustic Thresholds

    Using the best available science, NMFS has developed acoustic 
thresholds that identify the received level of underwater sound above 
which exposed marine mammals would be reasonably expected to be 
behaviorally harassed (equated to Level B harassment) or to incur PTS 
of some degree (equated to Level A harassment).
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source (e.g., frequency, predictability, duty cycle), the environment 
(e.g., bathymetry), and the receiving animals (hearing, motivation, 
experience, demography, behavioral context) and can be difficult to 
predict (Southall et al., 2007, Ellison et al., 2012). Based on what 
the available science indicates and the practical need to use a 
threshold based on a factor that is both predictable and measurable for 
most activities, NMFS uses a generalized acoustic threshold based on 
received level to estimate the onset of behavioral harassment. NMFS 
predicts that marine mammals are likely to be behaviorally harassed in 
a manner we consider Level B harassment when exposed to underwater 
anthropogenic noise above received levels of 160 dB re 1 [mu]Pa (rms) 
for impulsive and/or intermittent sources (e.g., impact pile driving) 
and 120 dB rms for continuous sources (e.g., vibratory driving). 
Skipjack's proposed activity includes the use of impulsive sources 
(geophysical survey equipment) therefore use of the 120 and 160 dB re 1 
[mu]Pa (rms) threshold is applicable.
    Level A harassment--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). The 
components of Skipjack's proposed activity that may result in the take 
of marine mammals include the use of impulsive 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: 
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.


[[Page 51136]]

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that will feed into identifying the area ensonified above the 
acoustic thresholds, which include source levels and transmission loss 
coefficient.
    The proposed survey would entail the use of HRG equipment. The 
distance to the isopleth corresponding to the threshold for Level B 
harassment was calculated for all HRG equipment with the potential to 
result in harassment of marine mammals. NMFS has developed an interim 
methodology for determining the rms sound pressure level 
(SPLrms) at the 160-dB isopleth for the purposes of 
estimating take by Level B harassment resulting from exposure to HRG 
survey equipment. This methodology incorporates frequency and some 
directionality to refine estimated ensonified zones and is described 
below:
    If only peak source sound pressure level (SPLpk) is given, the 
SPLrms can be roughly approximated by
[GRAPHIC] [TIFF OMITTED] TN27SE19.005

where [tau] is the pulse duration in second. If the pulse duration 
varies, the longest duration should be used, unless there is 
certainty regarding the portion of time a shorter duration will be 
used, in which case the result can be calculated/parsed 
appropriately.

    In order to account for the greater absorption of higher frequency 
sources, we recommend applying 20 log(r) with an absorption term 
[alpha][middot]r/1000 to calculate transmission loss (TL), as described 
in Eq.s (2) and (3) below.
[GRAPHIC] [TIFF OMITTED] TN27SE19.006

where r is the distance in meters, and [alpha] is absorption 
coefficient in dB/km.

    While the calculation of absorption coefficient varies with 
frequency, temperature, salinity, and pH, the largest factor driving 
the absorption coefficient is frequency. A simple formula to 
approximate the absorption coefficient (neglecting temperature, 
salinity, and pH) is provided by Richardson et al. (1995):
[GRAPHIC] [TIFF OMITTED] TN27SE19.007

where f is frequency in kHz. When a range of frequencies, is being 
used, the lower bound of the range should be used for this 
calculation, unless there is certainty regarding the portion of time 
a higher frequency will be used, in which case the result can be 
calculated/parsed appropriately.

    Further, if the beamwidth is less than 180[deg] and the angle of 
beam axis in respect to sea surface is known, the horizontal impact 
distance R should be calculated using
[GRAPHIC] [TIFF OMITTED] TN27SE19.008

where SL is the SPLrms at the source (1 m), [theta] is the beamwidth 
(in radian), and [phi] is the angle of beam axis in respect to sea 
surface (in radian) (Figure 1(a)).

    Finally, if the beam is pointed at a normal downward direction, Eq. 
(4) can be simplified as
[GRAPHIC] [TIFF OMITTED] TN27SE19.009

    The interim methodology described above was used to estimate 
isopleth distances to the Level B harassment threshold for the proposed 
HRG survey. NMFS considers the data provided by Crocker and Fratantonio 
(2016) to represent the best available information on source levels 
associated with HRG equipment and therefore recommends that source 
levels provided by Crocker and Fratantonio (2016) be incorporated in 
the method described above to estimate isopleth distances to the Level 
B harassment threshold. In 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. Table 4 in the IHA 
application shows the literature sources for the sound source levels 
that are shown in Table 1 and that were incorporated into the modeling 
of Level B isopleth distances to the Level B harassment threshold.
    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 harassment of marine mammals, sound produced 
by the AA Dura-Spark 400 sparker and the GeoSource 800 J sparker would 
propagate furthest to the Level B harassment threshold (Table 5); 
therefore, for the purposes of the exposure analysis, it was assumed 
the AA Dura-Spark or the GeoSource 800 J would be active during the 
entirety of the survey. Thus the distance to the isopleth corresponding 
to the threshold for Level B harassment for the AA Dura-Spark 400 and 
the GeoSource 800 J (estimated at 141 m; Table 5) was used as the basis 
of the take calculation for all marine mammals. Note that this is 
conservative as Skipjack has stated that for approximately 120 of the 
200 total survey days, neither the AA Dura-Spark nor the GeoSource 800 
J would be operated, and the source with the greatest potential 
isopleth distance to the Level B harassment threshold that would be 
operated during those 120 days would likely be a USBL, which has a 
smaller associated isopleth distance to the Level B harassment 
threshold (Table 5).

Table 5--Modeled Radial Distances From HRG Survey Equipment to Isopleths Corresponding to Level A Harassment and
                                          Level B Harassment Thresholds
----------------------------------------------------------------------------------------------------------------
                                       Radial distance to Level A harassment threshold (m) *          Radial
                                 ----------------------------------------------------------------   distance to
                                                                                                      Level B
                                  Low  frequency  Mid  frequency       High           Phocid        harassment
          Sound source               cetaceans       cetaceans       frequency       pinnipeds    threshold  (m)
                                    (peak SPL/      (peak SPL/       cetaceans     (underwater)  ---------------
                                      SELcum)         SELcum)       (peak SPL/      (peak SPL/      All marine
                                                                      SELcum)         SELcum)         mammals
----------------------------------------------------------------------------------------------------------------
                                          Shallow Sub-Bottom Profilers
----------------------------------------------------------------------------------------------------------------
TB Chirp III....................            -/<1               0            -/<1            -/<1              48
ET 216 Chirp....................            -/<1             -/0            -/<1             -/0               9

[[Page 51137]]

 
ET 424 Chirp....................             -/0             -/0             -/0             -/0               4
ET 512i Chirp...................             -/0             -/0             -/0             -/0               6
GeoPulse 5430...................            -/<1             -/0            -/<1             -/0              21
----------------------------------------------------------------------------------------------------------------
                                         Parametric Sub-Bottom Profilers
----------------------------------------------------------------------------------------------------------------
Innomar Parametric SBPs.........            -/<1            -/<1           -/1.2            -/<1               1
----------------------------------------------------------------------------------------------------------------
                                           Medium Sub-Bottom Profilers
----------------------------------------------------------------------------------------------------------------
AA Triple plate S-Boom (700/                -/<1             -/0           2.8/0             -/0              34
 1000J).........................
AA Dura-Spark 400...............            -/<1             -/0           2.8/0             -/0             141
GeoSource 400 J Sparker.........            -/<1             -/0           2.0/0             -/0              56
GeoSource 600 J Sparker.........            -/<1             -/0          3.2/<1            -/<1             112
GeoSource 800 J Sparker.........            -/<1             -/0          3.5/<1            -/<1             141
----------------------------------------------------------------------------------------------------------------
                                                 Acoustic Corers
----------------------------------------------------------------------------------------------------------------
Pangeo Acoustic Corer (LF Chirp)            -/<1             -/0            -/<1             -/0               4
Pangeo Acoustic Corer (HF Chirp)            -/<1             -/0            -/<1             -/0               4
----------------------------------------------------------------------------------------------------------------
                                              Acoustic Positioning
----------------------------------------------------------------------------------------------------------------
USBL and GAPS (all models)......             -/0             -/0            -/<1             -/0              50
----------------------------------------------------------------------------------------------------------------
* Distances to Level A harassment isopleths were calculated to determine the potential for Level A harassment to
  occur. Skipjack has not requested, and NMFS does not propose to authorize, the take by Level A harassment of
  any marine mammals.
- = not applicable; AA = Applied Acoustics; CF = Crocker and Fratantonio (2016); ET = EdgeTech; GAPS = Global
  Acoustic Positioning System; HF = high-frequency; J = joules; LF= low-frequency; m = meter; MF = mid-
  frequency; PW = Phocids in water; SBP = Sub-bottom profilers; SELcum = cumulative sound exposure level; SL =
  source level; SPLpk = zero to peak sound pressure level in decibel referenced to 1 micropascal (dB re 1
  [micro]Pa); TB = teledyne benthos; USBL = ultra-short baseline.

    Predicted distances to Level A harassment isopleths, which vary 
based on marine mammal functional hearing groups (Table 3), were also 
calculated. The updated acoustic thresholds for impulsive sounds (such 
as HRG survey equipment) contained in the Technical Guidance (NMFS, 
2018) were presented as dual metric acoustic thresholds using both 
cumulative sound exposure level (SELcum) and peak sound 
pressure level metrics. As dual metrics, NMFS considers onset of PTS 
(Level A harassment) to have occurred when either one of the two 
metrics is exceeded (i.e., the metric resulting in the largest 
isopleth). The SELcum metric considers both level and 
duration of exposure, as well as auditory weighting functions by marine 
mammal hearing group.
    When the NMFS Technical Guidance (2016) was published, in 
recognition of the fact that ensonified area/volume could be more 
technically challenging to predict because of the duration component in 
the new thresholds, we developed a User Spreadsheet that includes tools 
to help predict a simple isopleth that can be used in conjunction with 
marine mammal density or occurrence to help predict takes. We note that 
because of some of the assumptions included in the methods used for 
these tools, we anticipate that isopleths produced are typically going 
to be overestimates of some degree, which may result in some degree of 
overestimate of Level A harassment take. However, these tools offer the 
best way to predict appropriate isopleths when more sophisticated 3D 
modeling methods are not available, and NMFS continues to develop ways 
to quantitatively refine these tools, and will qualitatively address 
the output where appropriate. For mobile sources (such as HRG surveys), 
the User Spreadsheet predicts the closest distance at which a 
stationary animal would incur PTS if the sound source traveled by the 
animal in a straight line at a constant speed.
    Skipjack used the NMFS optional User Spreadsheet to calculate 
distances to Level A harassment isopleths based on SEL and used the 
spherical spreading loss model to calculate distances to Level A 
harassment isopleths based on peak SPL. Modeling of distances to 
isopleths corresponding to Level A harassment was performed for all 
types of HRG equipment proposed for use with the potential to result in 
harassment of marine mammals. Isopleth distances to Level A harassment 
thresholds for all types of HRG equipment and all marine mammal 
functional hearing groups are shown in Table 5. To be conservative, the 
largest isopleth distances for each functional hearing group were used 
to model potential exposures above the Level A harassment threshold for 
all species within that functional hearing group. Inputs to the NMFS 
optional User Spreadsheet for the GeoSource 800 J Sparker, which 
resulted in the greatest potential isopleth distance to the Level A 
harassment threshold for any of the functional hearing groups, are 
shown in Table 6.

[[Page 51138]]



 Table 6--Inputs to the NMFS Optional User Spreadsheet for the GeoSource
                              800 J Sparker
------------------------------------------------------------------------
 
------------------------------------------------------------------------
Source Level (RMS SPL)....................  203 dB re 1[mu]Pa.
Source Level (peak).......................  213 dB re 1[mu]Pa.
Weighting Factor Adjustment (kHz).........  0.05.
Source Velocity (meters/second)...........  2.06.
Pulse Duration (seconds)..................  0.0034.
1/Repetition rate (seconds)...............  2.43.
Duty Cycle................................  0.00.
------------------------------------------------------------------------

    Due to the small estimated distances to Level A harassment 
thresholds for all marine mammal functional hearing groups, based on 
both SELcum and peak SPL (Table 5), and in consideration of 
the proposed mitigation measures (see the Proposed Mitigation section 
for more detail), NMFS has determined that the likelihood of take of 
marine mammals in the form of Level A harassment occurring as a result 
of the proposed survey is so low as to be discountable, and we 
therefore do not propose to authorize the take by Level A harassment of 
any marine mammals.

Marine Mammal Occurrence

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations.
    The habitat-based density models produced by the Duke University 
Marine Geospatial Ecology Laboratory (Roberts et al., 2016, 2017, 2018) 
represent the best available information regarding marine mammal 
densities in the proposed survey area. The density data presented by 
Roberts et al. (2016, 2017, 2018) incorporates aerial and shipboard 
line-transect survey data from NMFS and other organizations and 
incorporates data from 8 physiographic and 16 dynamic oceanographic and 
biological covariates, and controls for the influence of sea state, 
group size, availability bias, and perception bias on the probability 
of making a sighting. These density models were originally developed 
for all cetacean taxa in the U.S. Atlantic (Roberts et al., 2016). In 
subsequent years, certain models have been updated on the basis of 
additional data as well as certain methodological improvements. 
Although these updated models (and a newly developed seal density 
model) are not currently publicly available, our evaluation of the 
changes leads to a conclusion that these represent the best scientific 
evidence available. More information, including the model results and 
supplementary information for each model, is available online at 
seamap.env.duke.edu/models/Duke-EC-GOM-2015/. Marine mammal density 
estimates in the project area (animals/km\2\) were obtained using these 
model results (Roberts et al., 2016, 2017, 2018). The updated models 
incorporate additional sighting data, including sightings from the NOAA 
Atlantic Marine Assessment Program for Protected Species (AMAPPS) 
surveys from 2010-2014 (NEFSC & SEFSC, 2011, 2012, 2014a, 2014b, 2015, 
2016).
    For purposes of the exposure analysis, density data from Roberts et 
al. (2016, 2017, 2018) were mapped using a geographic information 
system (GIS). The density coverages that included any portion of the 
proposed project area were selected for all survey months (see Figure 4 
in the IHA application for an example of density blocks used to 
determine monthly marine mammal densities within the project area). 
Monthly density data for each species were then averaged over the year 
to come up with a mean annual density value for each species. Estimated 
monthly and average annual density (animals per km\2\) of all marine 
mammal species that may be taken by the proposed survey are shown in 
Table 8 of the IHA application. The mean annual density values used to 
estimate take numbers are also shown in Table 7 below.

Take Calculation and Estimation

    Here we describe how the information provided above is brought 
together to produce a quantitative take estimate.
    In order to estimate the number of marine mammals predicted to be 
exposed to sound levels that would result in harassment, radial 
distances to predicted isopleths corresponding to harassment thresholds 
are calculated, as described above. Those distances are then used to 
calculate the area(s) around the HRG survey equipment predicted to be 
ensonified to sound levels that exceed harassment thresholds. The area 
estimated to be ensonified to relevant thresholds in a single day is 
then calculated, based on areas predicted to be ensonified around the 
HRG survey equipment and the estimated trackline distance traveled per 
day by the survey vessel. Skipjack estimates that proposed surveys will 
achieve a maximum daily track line distance of 110 km per day during 
proposed HRG surveys. This distance accounts for the vessel traveling 
at roughly 4 knots and accounts for non-active survey periods. Based on 
the maximum estimated distance to the Level B harassment threshold of 
141 m (Table 5) and the maximum estimated daily track line distance of 
110 km, an area of 31.1 km\2\ would be ensonified to the Level B 
harassment threshold per day during Skipjack's proposed HRG surveys. As 
described above, this is a conservative estimate as it assumes the HRG 
sources that result in the greatest isopleth distances to the Level B 
harassment threshold would be operated at all times during the 200 day 
survey.
    The number of marine mammals expected to be incidentally taken per 
day is then calculated by estimating the number of each species 
predicted to occur within the daily ensonified area (animals/km\2\), 
incorporating the estimated marine mammal densities as described above. 
Estimated numbers of each species taken per day are then multiplied by 
the total number of survey days (i.e., 200). The product is then 
rounded, to generate an estimate of the total number of instances of 
harassment expected for each species over the duration of the survey. A 
summary of this method is illustrated in the following formula:

Estimated Take = D x ZOI x # of days

Where:

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

    Using this method to calculate take, Skipjack estimated a total of 
2 takes by Level A harassment of 1 species (harbor porpoise) would 
occur, in the absence of mitigation (see Table 9 in the IHA application 
for the estimated number of Level A takes for all potential HRG 
equipment types). However, as described above, due to the very small 
estimated distances to Level A harassment thresholds (Table 5), and in 
consideration of the proposed mitigation measures, the likelihood of 
the proposed survey resulting in take in the form of Level A harassment 
is considered so low as to be discountable; therefore, we do not 
propose to authorize take of any marine mammals by Level A harassment. 
Proposed take numbers are shown in Table 7.

[[Page 51139]]



    Table 7--Total Numbers of Potential Incidental Take of Marine Mammals Proposed for Authorization and Proposed Takes as a Percentage of Population
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                                               Total
                                                              Density        Proposed        Estimated       Proposed       Total takes      proposed
                         Species                           (animals/ 100  takes by Level  takes by Level  takes by Level   proposed for     takes as a
                                                               km2)        A  harassment   B  harassment   B  harassment   authorization   percentage of
                                                                                                                                          population \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Fin whale...............................................         0.00124               0               8               8               8             0.2
Sei whale \2\...........................................         0.00001               0               0               1               1             0.1
Minke whale.............................................         0.00034               0               2               2               2             0.1
Humpback whale..........................................         0.00053               0               3               3               3             0.2
North Atlantic right whale..............................         0.00043               0               3               3               3             0.7
Sperm Whale \2\.........................................         0.00004               0               0               3               3             0.1
Atlantic white-sided dolphin \2\........................         0.00229               0              14              40              40             0.1
Atlantic spotted dolphin \2\............................         0.00124               0               8             100             100             0.2
Bottlenose dolphin (W. N. Atlantic Coastal Migratory)...          0.2355               0           1,465           1,465           1,465            22.1
Killer whale \2\........................................         0.00001               0               0               3               3            27.3
Short-finned pilot whale \2\............................         0.00031               0               2              20              20             0.1
Long-finned pilot whale \2\.............................         0.00031               0               2              20              20             0.1
Risso's dolphin \2\.....................................               0               0               0              30              30             0.4
Common dolphin..........................................         0.01328               0              83              83              83             0.1
Harbor porpoise.........................................         0.01277               0              79              79              79             0.2
Gray seal...............................................         0.00072               0               4               4               4             0.0
Harbor seal.............................................         0.00072               0               4               4               4             0.0
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Calculations of percentage of stock taken are based on the best available abundance estimate as shown in Table 2. In most cases the best available
  abundance estimate is provided by Roberts et al. (2016, 2017, 2018), when available, to maintain consistency with density estimates derived from
  Roberts et al. (2016, 2017, 2018). For North Atlantic right whales the best available abundance estimate is derived from the 2018 North Atlantic Right
  Whale Consortium 2018 Annual Report Card (Pettis et al., 2018).
\2\ The proposed number of authorized takes (Level B harassment only) for these species has been increased from the estimated take number to mean group
  size. Source for group size estimates are as follows: Sei whale: Kenney and Vigness-Raposa (2010); sperm whale: Barkaszi and Kelly (2019); killer
  whale: De Bruyn et al. (2013); Risso's dolphin: Kenney and Vigness-Raposa (2010); long-finned and short-finned pilot whale: Olson (2018); Atlantic
  spotted dolphin: Herzing and Perrin (2018); Atlantic white-sided dolphin: Cipriano (2018).

    Skipjack requested take authorization for three marine mammal 
species for which no takes were calculated based on the modeling 
approach described above: Killer whale, sei whale and Risso's dolphin. 
Though the modeling resulted in estimates of less than 1 take for these 
species, Skipjack determined that take of these species is possible due 
to low densities in some density blocks and general variability in the 
movements of these species. NMFS believes this is reasonable and we 
therefore propose to authorize take of these species.
    As described above, Roberts et al. (2016, 2017, 2018) produced 
density models to genus level for Globicephala spp. and did not 
differentiate between long-finned and shortfinned pilot whales. 
Similarly, Roberts et al. (2018) produced density models for all seals 
and did not differentiate by seal species. The take calculation 
methodology as described above resulted in an estimate of two pilot 
whale takes and four seal takes. Based on this estimate, Skipjack 
requested two takes each of short-finned and long-finned pilot whales, 
and four takes each of harbor and gray seals, based on an assumption 
that the modeled takes could occur to either of the respective species. 
We think this is a reasonable approach and therefore propose to 
authorize the take of four harbor seals, four gray seals, two short-
finned pilot whales and two long-finned pilot whales.
    Using the take methodology approach described above, the take 
estimates for the sei whale, sperm whale, killer whale, Risso's 
dolphin, Atlantic white-sided dolphin, spotted dolphin, long-finned and 
short-finned pilot whale were less than the average group sizes 
estimated for these species (Table 7). However, information on the 
social structures of these species indicates these species are likely 
to be encountered in groups. Therefore it is reasonable to 
conservatively assume that one group of each of these species will be 
taken during the proposed survey. We therefore propose to authorize the 
take of the average group size for these species to account for the 
possibility that the proposed survey encounters a group of any of these 
species or stocks (Table 7).

Proposed Mitigation

    In order to issue an IHA under Section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to such 
activity, and other means of effecting the least practicable impact on 
such species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of such species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting such 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation

[[Page 51140]]

(probability implemented as planned), and;
    (2) the practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.

Proposed Mitigation Measures

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

Marine Mammal Exclusion Zones, Buffer Zone and Monitoring Zone

    Marine mammal exclusion zones (EZ) would be established around the 
HRG survey equipment and monitored by protected species observers (PSO) 
during HRG surveys as follows:
     A 500-m EZ would be required for North Atlantic right 
whales;
     A 200 m EZ would be required for all other ESA-listed 
marine mammals (i.e., fin, sei and sperm whales); and
     A 100-m EZ would be required for all other marine mammals.
    If a marine mammal is detected approaching or entering the EZs 
during the proposed survey, the vessel operator would adhere to the 
shutdown procedures described below. In addition to the EZs described 
above, PSOs would visually monitor a 200 m Buffer Zone. During use of 
acoustic sources with the potential to result in marine mammal 
harassment (i.e., anytime the acoustic source is active, including 
ramp-up), occurrences of marine mammals within the Buffer Zone (but 
outside the EZs) would be communicated to the vessel operator to 
prepare for potential shutdown of the acoustic source. The Buffer Zone 
is not applicable when the EZ is greater than 100 meters. PSOs would 
also be required to observe a 500 m Monitoring Zone and record the 
presence of all marine mammals within this zone. In addition, any 
marine mammals observed within 141 m of the HRG equipment would be 
documented by PSOs as taken by Level B harassment. The zones described 
above would be based upon the radial distance from the active equipment 
(rather than being based on distance from the vessel itself).

Visual Monitoring

    A minimum of one NMFS-approved PSO must be on duty and conducting 
visual observations at all times during daylight hours (i.e., from 30 
minutes prior to sunrise through 30 minutes following sunset) and 30 
minutes prior to and during nighttime ramp-ups of HRG equipment. Visual 
monitoring would begin no less than 30 minutes prior to ramp-up of HRG 
equipment and would continue until 30 minutes after use of the acoustic 
source ceases or until 30 minutes past sunset. PSOs would establish and 
monitor the applicable EZs, Buffer Zone and Monitoring Zone as 
described above. Visual PSOs would coordinate to ensure 360[deg] visual 
coverage around the vessel from the most appropriate observation posts, 
and would conduct visual observations using binoculars and the naked 
eye while free from distractions and in a consistent, systematic, and 
diligent manner. PSOs would estimate distances to marine mammals 
located in proximity to the vessel and/or relevant using range finders. 
It would be the responsibility of the Lead PSO on duty to communicate 
the presence of marine mammals as well as to communicate and enforce 
the action(s) that are necessary to ensure mitigation and monitoring 
requirements are implemented as appropriate. Position data would be 
recorded using hand-held or vessel global positioning system (GPS) 
units for each confirmed marine mammal sighting.

Pre-Clearance of the Exclusion Zones

    Prior to initiating HRG survey activities, Skipjack would implement 
a 30-minute pre-clearance period. During pre-clearance monitoring 
(i.e., before ramp-up of HRG equipment begins), the Buffer Zone would 
also act as an extension of the 100 m EZ in that observations of marine 
mammals within the 200 m Buffer Zone would also preclude HRG operations 
from beginning. During this period, PSOs would ensure that no marine 
mammals are observed within 200 m of the survey equipment (500 m in the 
case of North Atlantic right whales). HRG equipment would not start up 
until this 200 m zone (or, 500 m zone in the case of North Atlantic 
right whales) is clear of marine mammals for at least 30 minutes. The 
vessel operator would notify a designated PSO of the planned start of 
HRG survey equipment as agreed upon with the lead PSO; the notification 
time should not be less than 30 minutes prior to the planned initiation 
of HRG equipment order to allow the PSOs time to monitor the EZs and 
Buffer Zone for the 30 minutes of pre-clearance. A PSO conducting pre-
clearance observations would be notified again immediately prior to 
initiating active HRG sources.
    If a marine mammal were observed within the relevant EZs or Buffer 
Zone during the pre-clearance period, initiation of HRG survey 
equipment would not begin until the animal(s) has been observed exiting 
the respective EZ or Buffer Zone, or, until an additional time period 
has elapsed with no further sighting (i.e., minimum 15 minutes for 
small odontocetes and seals, and 30 minutes for all other species). The 
pre-clearance requirement would include small delphinoids that approach 
the vessel (e.g., bow ride). PSOs would also continue to monitor the 
zone for 30 minutes after survey equipment is shut down or survey 
activity has concluded.

Ramp-Up of Survey Equipment

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

Shutdown Procedures

    If an HRG source is active and a marine mammal is observed within 
or entering a relevant EZ (as described above) an immediate shutdown of 
the HRG survey equipment would be required. When shutdown is called for 
by a PSO, the acoustic source would be immediately deactivated and any 
dispute resolved only following deactivation. Any PSO on duty would 
have the authority to delay the start of survey operations or to call 
for shutdown of the acoustic source if a marine mammal is detected 
within the applicable EZ. The vessel operator would establish and 
maintain clear lines of communication directly between PSOs on duty and 
crew controlling the HRG source(s) to ensure that shutdown commands are 
conveyed swiftly while allowing PSOs to maintain watch. Subsequent 
restart of the HRG equipment would only occur after the marine mammal 
has either been observed exiting the relevant EZ, or, until an 
additional time period has

[[Page 51141]]

elapsed with no further sighting of the animal within the relevant EZ 
(i.e., 15 minutes for small odontocetes and seals, and 30 minutes for 
large whales).
    Upon implementation of shutdown, the HRG source may be reactivated 
after the marine mammal that triggered the shutdown has been observed 
exiting the applicable EZ (i.e., the animal is not required to fully 
exit the Buffer Zone where applicable), or, following a clearance 
period of 15 minutes for small odontocetes and seals and 30 minutes for 
all other species with no further observation of the marine mammal(s) 
within the relevant EZ. If the HRG equipment shuts down for brief 
periods (i.e., less than 30 minutes) for reasons other than mitigation 
(e.g., mechanical or electronic failure) the equipment may be re-
activated as soon as is practicable at full operational level, without 
30 minutes of pre-clearance, only if PSOs have maintained constant 
visual observation during the shutdown and no visual detections of 
marine mammals occurred within the applicable EZs and Buffer Zone 
during that time. For a shutdown of 30 minutes or longer, or if visual 
observation was not continued diligently during the pause, pre-
clearance observation is required, as described above.
    The shutdown requirement would be waived for certain genera of 
small delphinids (i.e., Delphinus, Lagenorhynchus, Stenella, and 
Tursiops) under certain circumstances. If a delphinid(s) from these 
genera is visually detected approaching the vessel (i.e., to bow ride) 
or towed survey equipment, shutdown would not be required. If there is 
uncertainty regarding identification of a marine mammal species (i.e., 
whether the observed marine mammal(s) belongs to one of the delphinid 
genera for which shutdown is waived), PSOs would use best professional 
judgment in making the decision to call for a shutdown.
    If a species for which authorization has not been granted, or, a 
species for which authorization has been granted but the authorized 
number of takes have been met, approaches or is observed within the 
area encompassing the Level B harassment isopleth (141 m), shutdown 
would occur.

Vessel Strike Avoidance

    Vessel strike avoidance measures would include, but would not be 
limited to, the following, except under circumstances when complying 
with these requirements would put the safety of the vessel or crew at 
risk:
     All vessel operators and crew will maintain vigilant watch 
for cetaceans and pinnipeds, and slow down or stop their vessel to 
avoid striking these protected species;
     All vessel operators will comply with 10 knot (18.5 km/hr) 
or less speed restrictions in any SMA and DMA per NOAA guidance;
     All vessel operators will reduce vessel speed to 10 knots 
(18.5 km/hr) or less when any large whale, any mother/calf pairs, large 
assemblages of non-delphinoid cetaceans are observed near (within 100 m 
(330 ft)) an underway vessel;
     All survey vessels will maintain a separation distance of 
500 m (1640 ft) or greater from any sighted North Atlantic right whale;
     If underway, vessels must steer a course away from any 
sighted North Atlantic right whale at 10 knots (18.5 km/hr) or less 
until the 500 m (1640 ft) minimum separation distance has been 
established. If a North Atlantic right whale is sighted in a vessel's 
path, or within 100 m (330 ft) to an underway vessel, the underway 
vessel must reduce speed and shift the engine to neutral. Engines will 
not be engaged until the North Atlantic right whale has moved outside 
of the vessel's path and beyond 100 m. If stationary, the vessel must 
not engage engines until the North Atlantic right whale has moved 
beyond 100 m;
     All vessels will maintain a separation distance of 100 m 
(330 ft) or greater from any sighted non-delphinoid cetacean. If 
sighted, the vessel underway must reduce speed and shift the engine to 
neutral, and must not engage the engines until the non-delphinoid 
cetacean has moved outside of the vessel's path and beyond 100 m. If a 
survey vessel is stationary, the vessel will not engage engines until 
the non-delphinoid cetacean has moved out of the vessel's path and 
beyond 100 m;
     All vessels will maintain a separation distance of 50 m 
(164 ft) or greater from any sighted delphinoid cetacean. Any vessel 
underway remain parallel to a sighted delphinoid cetacean's course 
whenever possible, and avoid excessive speed or abrupt changes in 
direction. Any vessel underway reduces vessel speed to 10 knots (18.5 
km/hr) or less when pods (including mother/calf pairs) or large 
assemblages of delphinoid cetaceans are observed. Vessels may not 
adjust course and speed until the delphinoid cetaceans have moved 
beyond 50 m and/or the abeam of the underway vessel;
     All vessels will maintain a separation distance of 50 m 
(164 ft) or greater from any sighted pinniped; and
     All vessels underway will not divert or alter course in 
order to approach any whale, delphinoid cetacean, or pinniped. Any 
vessel underway will avoid excessive speed or abrupt changes in 
direction to avoid injury to the sighted cetacean or pinniped.
    Skipjack will ensure that vessel operators and crew maintain a 
vigilant watch for marine mammals by slowing down or stopping the 
vessel to avoid striking marine mammals. Project-specific training will 
be conducted for all vessel crew prior to the start of survey 
activities. Confirmation of the training and understanding of the 
requirements will be documented on a training course log sheet. Signing 
the log sheet will certify that the crew members understand and will 
comply with the necessary requirements throughout the survey 
activities.

Seasonal Operating Requirements

    As described above, the section of the proposed survey area 
partially overlaps with a portion of a North Atlantic right whale SMA 
off the mouth of Delaware Bay. This SMA is active from November 1 
through April 30 of each year. Any survey vessels that are >65 ft in 
length would be required to adhere to the mandatory vessel speed 
restrictions (<10 kn) when operating within the SMA during times when 
the SMA is active. In addition, between watch shifts, members of the 
monitoring team would consult NMFS' North Atlantic right whale 
reporting systems for the presence of North Atlantic right whales 
throughout survey operations. Members of the monitoring team would also 
monitor the NMFS North Atlantic right whale reporting systems for the 
establishment of Dynamic Management Areas (DMA). If NMFS should 
establish a DMA in the survey area while surveys are underway, Skipjack 
would contact NMFS within 24 hours of the establishment of the DMA to 
determine whether alteration of survey activities was warranted to 
avoid right whales to the extent possible.
    The proposed mitigation measures are designed to avoid the already 
low potential for injury in addition to some instances of Level B 
harassment, and to minimize the potential for vessel strikes. Further, 
we believe the proposed mitigation measures are practicable for the 
applicant to implement. Skipjack has proposed additional mitigation 
measures in addition to the measures described above; for information 
on the measures proposed by Skipjack, see Section 11 of the IHA 
application.
    There are no known marine mammal rookeries or mating or calving 
grounds in the survey area that would otherwise potentially warrant 
increased mitigation measures for marine mammals or their

[[Page 51142]]

habitat (or both). The proposed survey would occur in an area that has 
been identified as a biologically important area for migration for 
North Atlantic right whales. However, given the small spatial extent of 
the survey area relative to the substantially larger spatial extent of 
the right whale migratory area, the survey is not expected to 
appreciably reduce migratory habitat nor to negatively impact the 
migration of North Atlantic right whales, thus mitigation to address 
the proposed survey's occurrence in North Atlantic right whale 
migratory habitat is not warranted.
    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 
effecting the least practicable impact on the affected species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance.

Proposed Monitoring and Reporting

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

Proposed Monitoring Measures

    As described above, visual monitoring would be performed by 
qualified and NMFS-approved PSOs. Skipjack would use independent, 
dedicated, trained PSOs, meaning that the PSOs must be employed by a 
third-party observer provider, must have no tasks other than to conduct 
observational effort, collect data, and communicate with and instruct 
relevant vessel crew with regard to the presence of marine mammals and 
mitigation requirements (including brief alerts regarding maritime 
hazards), and must have successfully completed an approved PSO training 
course appropriate for their designated task. Skipjack would provide 
resumes of all proposed PSOs (including alternates) to NMFS for review 
and approval at least 45 days prior to the start of survey operations.
    During survey operations (e.g., any day on which use of an HRG 
source is planned to occur), a minimum of one PSO must be on duty and 
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) and nighttime ramp-ups of HRG 
equipment. Visual monitoring would begin no less than 30 minutes prior 
to initiation of HRG survey equipment and would continue until one hour 
after use of the acoustic source ceases or until 30 minutes past 
sunset. PSOs would coordinate to ensure 360[deg] visual coverage around 
the vessel from the most appropriate observation posts, and would 
conduct visual observations using binoculars and the naked eye while 
free from distractions and in a consistent, systematic, and diligent 
manner. PSOs may be on watch for a maximum of four consecutive hours 
followed by a break of at least two hours between watches and may 
conduct a maximum of 12 hours of observation per 24-hour period. In 
cases where multiple vessels are surveying concurrently, any 
observations of marine mammals would be communicated to PSOs on all 
survey vessels.
    PSOs would be equipped with binoculars and have the ability to 
estimate distances to marine mammals located in proximity to the vessel 
and/or exclusion zone using range finders. Reticulated binoculars will 
also be available to PSOs for use as appropriate based on conditions 
and visibility to support the monitoring of marine mammals. Position 
data would be recorded using hand-held or vessel GPS units for each 
sighting. Observations would take place from the highest available 
vantage point on the survey vessel. General 360-degree scanning would 
occur during the monitoring periods, and target scanning by the PSO 
would occur when alerted of a marine mammal presence.
    During good conditions (e.g., daylight hours; Beaufort sea state 
(BSS) 3 or less), to the maximum extent practicable, PSOs would conduct 
observations when the acoustic source is not operating for comparison 
of sighting rates and behavior with and without use of the acoustic 
source and between acquisition periods. Any observations of marine 
mammals by crew members aboard any vessel associated with the survey 
would be relayed to the PSO team.
    Data on all PSO observations would be recorded based on standard 
PSO collection requirements. This would include dates, times, and 
locations of survey operations; dates and times of observations, 
location and weather; details of marine mammal sightings (e.g., 
species, numbers, behavior); and details of any observed marine mammal 
take that occurs (e.g., noted behavioral disturbances).

Proposed Reporting Measures

    Within 90 days after completion of survey activities, a final 
technical report will be provided to NMFS that fully documents the 
methods and monitoring protocols, summarizes the data recorded during 
monitoring, summarizes the number of marine mammals estimated to have 
been taken 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

[[Page 51143]]

the final report prior to acceptance by NMFS.
    In addition to the final technical report, Skipjack will provide 
the reports described below as necessary during survey activities. In 
the unanticipated event that Skipjack's survey activities lead to an 
injury (Level A harassment) or mortality (e.g., ship-strike, gear 
interaction, and/or entanglement) of a marine mammal, Skipjack would 
immediately cease the specified activities and report the incident to 
the Chief of the Permits and Conservation Division, Office of Protected 
Resources and the NMFS New England/Mid-Atlantic Stranding Coordinator. 
The report would include the following information:
     Time, date, and location (latitude/longitude) of the 
incident;
     Name and type of vessel involved;
     Vessel's speed during and leading up to the incident;
     Description of the incident;
     Status of all sound source use in the 24 hours preceding 
the incident;
     Water depth;
     Environmental conditions (e.g., wind speed and direction, 
Beaufort sea state, cloud cover, and visibility);
     Description of all marine mammal observations in the 24 
hours preceding the incident;
     Species identification or description of the animal(s) 
involved;
     Fate of the animal(s); and
     Photographs or video footage of the animal(s) (if 
equipment is available).
    Activities would not resume until NMFS is able to review the 
circumstances of the event. NMFS would work with Skipjack to minimize 
reoccurrence of such an event in the future. Skipjack would not resume 
activities until notified by NMFS.
    In the event that Skipjack discovers an injured or dead marine 
mammal and determines that the cause of the injury or death is unknown 
and the death is relatively recent (i.e., in less than a moderate state 
of decomposition), Skipjack would immediately report the incident to 
the Chief of the Permits and Conservation Division, Office of Protected 
Resources and the NMFS New England/Mid-Atlantic Stranding Coordinator. 
The report would include the same information identified in the 
paragraph above. Activities would be able to continue while NMFS 
reviews the circumstances of the incident. NMFS would work with 
Skipjack to determine if modifications in the activities are 
appropriate.
    In the event that Skipjack discovers an injured or dead marine 
mammal and determines that the injury or death is not associated with 
or related to the activities authorized in the IHA (e.g., previously 
wounded animal, carcass with moderate to advanced decomposition, or 
scavenger damage), Skipjack would report the incident to the Chief of 
the Permits and Conservation Division, Office of Protected Resources, 
and the NMFS New England/Mid-Atlantic Regional Stranding Coordinator, 
within 24 hours of the discovery. Skipjack would provide photographs or 
video footage (if available) or other documentation of the stranded 
animal sighting to NMFS. Skipjack may continue its operations in such a 
case.

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any responses (e.g., intensity, duration), the context 
of any responses (e.g., critical reproductive time or location, 
migration), as well as effects on habitat, and the likely effectiveness 
of the mitigation. We also assess the number, intensity, and context of 
estimated takes by evaluating this information relative to population 
status. Consistent with the 1989 preamble for NMFS's implementing 
regulations (54 FR 40338; September 29, 1989), the impacts from other 
past and ongoing anthropogenic activities are incorporated into this 
analysis via their impacts on the environmental baseline (e.g., as 
reflected in the regulatory status of the species, population size and 
growth rate where known, ongoing sources of human-caused mortality, or 
ambient noise levels).
    To avoid repetition, our analysis applies to all the species listed 
in Table 2, given that NMFS expects the anticipated effects of the 
proposed survey to be similar in nature.
    NMFS does not anticipate that serious injury or mortality would 
occur as a result of Skipjack's proposed survey, even in the absence of 
proposed mitigation. Thus the proposed authorization does not authorize 
any serious injury or mortality. As discussed in the Potential Effects 
section, non-auditory physical effects and vessel strike are not 
expected to occur. Additionally and as discussed previously, given the 
nature of activity and sounds sources used and especially in 
consideration of the required mitigation, Level A harassment is neither 
anticipated nor authorized. We expect 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, reactions that are considered to be of 
low severity and with no lasting biological consequences (e.g., 
Southall et al., 2007).
    Effects on individuals that are taken by Level B harassment, on the 
basis of reports in the literature as well as monitoring from other 
similar activities, will likely be limited to reactions such as 
increased swimming speeds, increased surfacing time, or decreased 
foraging (if such activity were occurring) (e.g., Thorson and Reyff, 
2006; HDR, Inc., 2012; Lerma, 2014). Most likely, individuals will 
simply move away from the sound source and temporarily avoid the area 
where the survey is occurring. We expect that any avoidance of the 
survey area by marine mammals would be temporary in nature and that any 
marine mammals that avoid the survey area during the survey activities 
would not be permanently displaced. 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. Instances of more severe behavioral harassment are 
expected to be minimized by proposed mitigation and monitoring 
measures.
    In addition to being temporary and short in overall duration, the 
acoustic footprint of the proposed survey is small relative to the 
overall distribution of the animals in the area and their use of the 
area. Feeding behavior is not likely to be significantly impacted. Prey 
species are mobile and are broadly distributed throughout the project 
area; therefore, marine mammals that may be temporarily displaced 
during survey activities are expected to be able to resume foraging 
once they have moved away from areas with disturbing levels of 
underwater noise. Because of the temporary nature of the disturbance 
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-

[[Page 51144]]

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. The proposed survey area overlaps a portion of a 
biologically important migratory area for North Atlantic right whales 
(effective March-April and November-December) that extends from 
Massachusetts to Florida (LaBrecque, et al., 2015). Off the coasts of 
Delaware and Maryland, this biologically important migratory area 
extends from the coast to beyond the shelf break. Due to the fact that 
that the proposed survey is temporary and the spatial extent of sound 
produced by the survey would very small relative to the spatial extent 
of the available migratory habitat in the area, right whale migration 
is not expected to be impacted by the proposed survey.
    Potential impacts to marine mammal habitat were discussed 
previously in this document (see Potential Effects of the Specified 
Activity on Marine Mammals and their Habitat). Marine mammal habitat 
may be impacted by elevated sound levels, but these impacts would be 
temporary. Repeated exposures of individuals to relatively low levels 
of sound outside of preferred habitat areas are unlikely to 
significantly disrupt critical behaviors. We expect that animals 
disturbed by sound associated with the proposed survey would simply 
avoid the area during the survey in favor of other, similar habitats.
    As described above, North Atlantic right, humpback, and minke 
whales, and gray and harbor seals are experiencing ongoing UMEs. For 
North Atlantic right whales, as described above, no injury as a result 
of the proposed project is expected or proposed for authorization, and 
Level B harassment takes of right whales are expected to be in the form 
of avoidance of the immediate area of the proposed survey. In addition, 
the number of takes proposed for authorization above the Level B 
harassment threshold are minimal (i.e., 3). As no injury or mortality 
is expected or proposed for authorization, and Level B harassment of 
North Atlantic right whales will be reduced to the level of least 
practicable adverse impact through use of proposed mitigation measures, 
the proposed authorized takes of right whales would not exacerbate or 
compound the ongoing UME in any way.
    Similarly, no injury or mortality is expected or proposed for 
authorization for any of the other species with UMEs, Level B 
harassment will be reduced to the level of least practicable adverse 
impact through use of proposed mitigation measures, and the proposed 
authorized takes would not exacerbate or compound the ongoing UMEs. For 
minke whales, although the ongoing UME is under investigation (as 
occurs for all UMEs), this event does not provide cause for concern 
regarding population level impacts, as the likely population abundance 
is greater than 20,000 whales. Even though the PBR value is based on an 
abundance for U.S. waters that is negatively biased and a small 
fraction of the true population abundance, annual M/SI does not exceed 
the calculated PBR value for minke whales. With regard to humpback 
whales, the UME does not yet provide cause for concern regarding 
population-level impacts. Despite the UME, the relevant population of 
humpback whales (the West Indies breeding population, or distinct 
population segment (DPS)) remains healthy. The West Indies DPS, which 
consists of the whales whose breeding range includes the Atlantic 
margin of the Antilles from Cuba to northern Venezuela, and whose 
feeding range primarily includes the Gulf of Maine, eastern Canada, and 
western Greenland, was delisted. The status review identified harmful 
algal blooms, vessel collisions, and fishing gear entanglements as 
relevant threats for this DPS, but noted that all other threats are 
considered likely to have no or minor impact on population size or the 
growth rate of this DPS (Bettridge et al., 2015). As described in 
Bettridge et al. (2015), the West Indies DPS has a substantial 
population size (i.e., approximately 10,000; Stevick et al., 2003; 
Smith et al., 1999; Bettridge et al., 2015), and appears to be 
experiencing consistent growth. With regard to gray and harbor seals, 
although the ongoing UME is under investigation, 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 (345) is well below PBR (2,006) (Hayes et al., 2018). 
For gray seals, the population abundance in the United States is over 
27,000, with an estimated abundance including seals in Canada of 
approximately 505,000, and abundance is likely increasing in the U.S. 
Atlantic EEZ as well as in Canada (Hayes et al., 2018).
    The proposed mitigation measures are expected to reduce the number 
and/or severity of takes by (1) giving animals the opportunity to move 
away from the sound source before HRG survey equipment reaches full 
energy; (2) preventing animals from being exposed to sound levels that 
may otherwise result in injury or more severe behavioral responses. 
Additional vessel strike avoidance requirements will further mitigate 
potential impacts to marine mammals during vessel transit to and within 
the survey area.
    NMFS concludes that exposures to marine mammal species and stocks 
due to Skipjack's proposed survey would result in only short-term 
(temporary and short in duration) effects to individuals exposed. 
Marine mammals may temporarily avoid the immediate area, but are not 
expected to permanently abandon the area. Major shifts in habitat use, 
distribution, or foraging success are not expected. NMFS does not 
anticipate the proposed take estimates to impact annual rates of 
recruitment or survival.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No mortality, serious injury, or Level A harassment is 
anticipated or authorized;
     The anticipated impacts of the proposed activity on marine 
mammals would primarily be in the form of temporary behavioral changes 
due to avoidance of the area around the survey vessel;
     The availability of alternate areas of similar habitat 
value (for foraging, etc.) for marine mammals that may temporarily 
vacate the survey area during the proposed survey to avoid exposure to 
sounds from the activity;
     The proposed project area does not contain known areas of 
significance for mating or calving;
     Effects on species that serve as prey species for marine 
mammals from the proposed survey would be minor and temporary and would 
not be expected to reduce the availability of prey or to affect marine 
mammal feeding;
     The proposed mitigation measures, including visual and 
acoustic monitoring, exclusion zones, and shutdown measures, 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

[[Page 51145]]

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. Additionally, other qualitative 
factors may be considered in the analysis, such as the temporal or 
spatial scale of the activities.
    The numbers of marine mammals that we propose for authorization to 
be taken, for all species and stocks, would be considered small 
relative to the relevant stocks or populations (less than 28 percent 
for two of seventeen species and stocks, and less than 1 percent for 
all remaining species and stocks). See Table 7. 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 (16 U.S.C. 
1531 et seq.) requires that each Federal agency insure that any action 
it authorizes, funds, or carries out is not likely to jeopardize the 
continued existence of any endangered or threatened species or result 
in the destruction or adverse modification of designated critical 
habitat. To ensure ESA compliance for the issuance of IHAs, NMFS 
consults internally, in this case with the NMFS Greater Atlantic 
Regional Fisheries Office (GARFO), whenever we propose to authorize 
take for endangered or threatened species.
    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 whale. 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 offshore of Delaware and along potential submarine cable routes 
to a landfall location in Delaware or Maryland, from the date of 
issuance for a period of one year, 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 
[action]. 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.
    On a case-by-case basis, NMFS may issue a one-year IHA renewal with 
an additional 15 days for public comments when (1) another year of 
identical or nearly identical activities as described in the Specified 
Activities section of this notice is planned or (2) the activities as 
described in the Specified Activities section of this notice would not 
be completed by the time the IHA expires and a Renewal would allow for 
completion of the activities beyond that described in the Dates and 
Duration section of this notice, provided all of the following 
conditions are met:
     A request for renewal is received no later than 60 days 
prior to expiration of the current IHA;
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested Renewal 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 
because only a subset of the initially analyzed activities remain to be 
completed under the Renewal);
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized;
     Upon review of the request for Renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: September 24, 2019.
Donna S. Wieting,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2019-20997 Filed 9-26-19; 8:45 am]
 BILLING CODE 3510-22-P