[Federal Register Volume 86, Number 195 (Wednesday, October 13, 2021)]
[Notices]
[Pages 56902-56922]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-22191]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XB492]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to the Parallel Thimble Shoal Tunnel 
Project in Virginia Beach, Virginia

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

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

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SUMMARY: NMFS has received a request from the Chesapeake Tunnel Joint 
Venture (CTJV) for authorization to take marine mammals incidental to 
the Parallel Thimble Shoal Tunnel Project (PTST) in Virginia Beach, 
Virginia. 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 document. 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 November 
12, 2021.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be sent to 
[email protected].
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments received electronically, including 
all attachments, must not exceed a 25-megabyte file size. Attachments 
to electronic comments will be accepted in Microsoft Word or Excel or 
Adobe PDF file formats only. All comments received are a part of the 
public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.

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

SUPPLEMENTARY INFORMATION:

Background

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

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment.
    This action is consistent with categories of activities identified 
in Categorical Exclusion B4 (IHAs with no anticipated serious injury or 
mortality) of the Companion Manual for NOAA Administrative Order 216-
6A, which do not individually or cumulatively have the potential for 
significant impacts on the quality of the human environment and for 
which we have not identified any extraordinary circumstances that would 
preclude this categorical exclusion. Accordingly, NMFS has 
preliminarily determined that the issuance of the proposed IHA 
qualifies to be categorically excluded from further NEPA review.
    We will review all comments submitted in response to this 
notification prior to concluding our NEPA process or making a final 
decision on the IHA request.

Summary of Request

    On September 21, 2021, NMFS received an application from CTJV 
requesting an IHA to take small numbers of five species (harbor seal 
(Phoca vitulina), gray seal (Halichoerus grypus), bottlenose dolphin 
(Tursiops truncatus), harbor porpoise (Phocoena

[[Page 56903]]

phocoena) and humpback whale (Megaptera novaeangliae)) of marine 
mammals incidental to pile driving and removal associated with the PTST 
Project. The application was deemed adequate and complete on September 
30, 2021. CTJV's request is for take of a small number of these species 
by Level A or Level B harassment. Neither CTJV nor NMFS expects serious 
injury or mortality to result from this activity and, therefore, an IHA 
is appropriate. NMFS previously issued IHAs to CTJV for similar work 
(83 FR 36522; July 30, 2018; 85 FR 16061; March 20, 2020; and 86 FR 
14606; March 17, 2021). However, due to design and schedule changes 
only a small portion of that work was conducted under those issued 
IHAs. This proposed IHA covers 1 year of a 5 year project.

Description of Proposed Activity

Overview

    The purpose of the project is to build an additional two lane 
vehicle tunnel under the navigation channel as part of the Chesapeake 
Bay Bridge and Tunnel (CBBT). The PTST project will address existing 
constraints to regional mobility based on current traffic volume, 
improve safety, improve the ability to conduct necessary maintenance 
with minimal impact to traffic flow, and ensure reliable hurricane 
evacuation routes. In-water pile driving is needed to create vessel 
moorings, temporary work trestles and Support of Excavation walls on 
islands at either end of the tunnel. The work in this application 
involves the installation of 722 36-inch and 42 42-inch steel piles. 
The project will take no more than 252 days of in-water pile work.
    The pile driving/removal can result in take of marine mammals from 
sound in the water which results in behavioral harassment or auditory 
injury.

Dates and Duration

    This project is ongoing under an existing IHA (86 FR 14606; March 
17, 2021). Because of new understanding of the geology of the area, 
significant revisions have been made to the plans and required work 
including switching some piles from wood to steel (which produces 
louder sound on installation), and increasing the size and number of 
piles. The IHA proposed here will thus supersede the existing IHA once 
it is issued and be effective for 1 year from the date of issuance.

Specific Geographic Region

    The PTST project is located between Portal Islands 1 and 2 of the 
CBBT as shown in Figure 1. A 6,525 lineal foot (ft) (1989 m) tunnel 
will be bored underneath the Thimble Shoal Channel connecting the 
Portal Islands located near the mouth of the Chesapeake Bay. The CBBT 
is a 23-mile (37 km) long facility that connects the Hampton Roads area 
of Virginia to the Eastern Shore of Virginia. Water depths within the 
PTST construction area range from 0 to 60 ft (18.2 m) below Mean Lower 
Low Water (MLLW). The Thimble Shoal Channel is 1,000 ft (305 m) wide, 
is authorized to a depth of -55 ft (16.8 m) below MLLW, and is 
maintained at a depth of 50 ft (15.2 m) MLLW.
BILLING CODE 3510-22-P

[[Page 56904]]

[GRAPHIC] [TIFF OMITTED] TN13OC21.003

BILLING CODE 3510-22-C

Detailed Description of Specific Activity

    The PTST project consists of the construction of a two lane tunnel 
parallel and to the west of the existing tunnel, connecting Portal 
Islands 1 and 2. A tunnel boring machine (TBM) will both excavate 
material and construct the tunnel as it progresses from Portal Island 
No. 1 to Portal Island No. 2. Precast concrete tunnel segments will be 
transported to the TBM for installation. The TBM will assemble the 
tunnel segments in-place as the tunnel is bored. After the tunnel 
structure is completed, final upland work for the PTST Project will 
include installation of the final roadway, lighting, finishes, 
mechanical systems, and other required internal systems for tunnel use 
and function. In addition, the existing fishing pier will be repaired 
and refurbished.
    Descriptions of additional upland activities may be found in the 
application but such actions will not affect marine mammals and are not 
described here.
    Proposed in-water activities during this IHA include the following 
and are shown in Table 1:
     Mooring piles: These are constructed of 28 36-inch steel 
pile piles on Portal Island No. 1 and 16 36-inch steel pile piles on 
Portal Island No. 2. Installation will be by vibratory hammer with a 
bubble curtain;
     Two engineered berms: Approximately 1,395 ft (425 m) in 
length for Portal Island No. requiring 316 36-inch steel interlocked 
pipe piles (209 on west side; 107 on east side) and

[[Page 56905]]

approximately 1,354 ft (451 m) in length for Portal Island No. 2 
requiring 338 piles of the same size and type (204 piles on west side; 
134 on east side). Each berm will extend channelward from its portal 
island. Construction methods will include impact pile driving as well 
as using a down-the-hole to create holes in the substrate for the 
piles. Once the piles are advanced through an existing rock layer (made 
of rocks previously placed for the earlier tunnel) using DTH, they are 
driven to final grade via traditional impact driving methods. A special 
bubble curtain system encompasses the entire area (see Application 
Appendix A);
     Two temporary Omega trestles: 26 42-inch steel pipe piles 
on Portal Island No. 1 and 24 36 inch and 16 42-inch steel pipe piles 
on Portal Island No. 2. These trestles will be offset to the west side 
of each engineered berm, extending channelward from each island. 
Construction methods will include vibratory hammer with bubble curtain 
with impact pile driving only as needed. This will be the methods for 
all piles on Portal Island 1 and the 42-inch piles on Portal Island No. 
2. The 36-inch piles on Portal Island No. 2 will be installed with DTH 
and an impact hammer with bubble curtain.
    Table 1 provides a summary of the pile driving activities. Most in-
water construction activities would involve multiple pile systems 
working simultaneously. There could be as many as three systems working 
simultaneously, with no more than two at a single island. Table 2 shows 
the potential simultaneous driving scenarios on each island and 
project-wide and provides best estimates of the days for each scenario.
    In summary, the project period includes 252 days of pile driving 
and DTH activities for which incidental take authorization is 
requested.

                     Table 1--Summary of Pile Driving Activities and User Spreadsheet Inputs
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                                                                                        Minutes/
                  Method                            Pile type            Number of     strikes per    Piles per
                                                                           piles          pile           day
----------------------------------------------------------------------------------------------------------------
Vibratory, or............................  42-inch steel..............           42              12            2
Impact...................................                                                     1,000            4
Vibratory................................  36-inch steel..............           44              12            4
DTH, and.................................  36-inch steel..............           24          36,000            2
Impact...................................                                                     1,000            2
DTH, and.................................  36-inch steel interlocking.          654          36,000       3 or 6
Impact...................................                                                      1000            6
                                          ----------------------------------------------------------------------
    Totals...............................  ...........................          764  ..............  ...........
----------------------------------------------------------------------------------------------------------------
All User spreadsheet calculations use Transmission Loss = 15 and standard weighting factor adjustments. See
  Estimated Take section for discussion of User Spreadsheet.


                                     Table 2--Simultaneous Driving Scenarios
----------------------------------------------------------------------------------------------------------------
                                                                      Days of         Days of         Days of
                                                                   simultaneous    simultaneous    simultaneous
               Activity (each mention is 1 system)                driving island    driving on      driving at
                                                                         1           island 2      both islands
----------------------------------------------------------------------------------------------------------------
Impact + DTH....................................................             124             147              48
DTH + Vibratory.................................................              10               6               2
Impact + Vibratory..............................................              10               6               1
Impact + DTH + DTH..............................................               0               0              22
DTH + DTH + Vibratory...........................................               0               0               6
DTH + Vibratory + Impact........................................               0               0               8
Impact + Impact + DTH...........................................               0               0              19
                                                                 -----------------------------------------------
    Totals......................................................             144             159             106
----------------------------------------------------------------------------------------------------------------

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

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history, of the potentially affected species. 
Additional information regarding population trends and threats may be 
found in NMFS's Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and more general information about these species 
(e.g., physical and behavioral descriptions) may be found on NMFS's 
website (https://www.fisheries.noaa.gov/find-species).
    Table 3 lists all species with expected potential for occurrence in 
the project area in Chesapeake Bay and summarizes information related 
to the population or stock, including regulatory status under the MMPA 
and Endangered Species Act (ESA) and potential biological removal 
(PBR), where known. For taxonomy, we follow Committee on Taxonomy 
(2020). PBR is defined by the MMPA as the maximum number of animals, 
not including natural mortalities, that may be removed from a marine 
mammal stock while allowing that stock to reach or maintain its optimum 
sustainable population (as described in NMFS's SARs). While no 
mortality is anticipated or authorized here, PBR and annual serious 
injury and mortality from anthropogenic sources are included here as 
gross indicators of the status of the species and other threats.

[[Page 56906]]

    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS's stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS's U.S. Atlantic SARs (e.g., Hayes et al., 2021).

                    Table 3--Species That Spatially Co-Occur With the Activity to the Degree That Take Is Reasonably Likely To Occur
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/ MMPA status;   Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \1\          abundance survey) \2\               SI \3\
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                                          Order Cetartiodactyla--Cetacea--Superfamily Mysticeti (baleen whales)
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Family Balaenopteridae (rorquals):
    Humpback whale..................  Megaptera novaeangliae.  Gulf of Maine..........  -,-; N              1,393 (0; 1,375, 2016)         22         58
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                            Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Delphinidae:
    Bottlenose dolphin..............  Tursiops truncatus.....  WNA Coastal, Northern    -,-; Y              6,639 (0.41; 4,759;            48  12.2-21.5
                                                                Migratory.                                   2011).
                                                               WNA Coastal, Southern    -,-; Y              3,751 (0.06; 2,353;            23        0-8
                                                                Migratory.                                   2011).
                                                               Northern North Carolina  -,-; Y              823 (0.06; 782; 2017).        7.8     7.2-30
                                                                Estuarine System.
Family Phocoenidae (porpoises):
    Harbor porpoise.................  Phocoena phocoena......  Gulf of Maine/Bay of     -, -; N             95,543 (0.31; 74,034;         851        217
                                                                Fundy.                                       2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         Order Carnivora--Superfamily Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocidae (earless seals):
    Harbor seal.....................  Phoca vitulina.........  WNA....................  -; N                75,834 (0.1; 66,884,        2,006        350
                                                                                                             2012).
    Gray seal \4\...................  Halichoerus grypus.....  WNA....................  -; N                27,131 (0.19, 23,158,       1,359      4,729
                                                                                                             2016).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\2\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\3\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual Mortality/Serious Injury (M/SI) often cannot be determined precisely and is in some cases presented as a
  minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases.
\4\ The NMFS stock abundance estimate applies to U.S. population only, however the actual stock abundance is approximately 505,000. The PBR value is
  estimated for the U.S. population, while the M/SI estimate is provided for the entire gray seal stock (including animals in Canada).

    Humpback whales, bottlenose dolphin, harbor porpoise, harbor seal, 
and gray seal spatially co-occur with the activity to the degree that 
take is reasonably likely to occur, and we have proposed authorizing 
take of these species. All species that could potentially occur in the 
proposed survey areas are included in the CTJV's IHA application (see 
application, Table 4). North Atlantic right whale and fin whale could 
potentially occur in the area. However the spatial and temporal 
occurrence of these species is very rare, the species are readily 
observed, and the applicant would shut down pile driving if they enter 
the project area. Thus take is not expected to occur, and they are not 
discussed further.

Humpback Whale

    The humpback whale is found worldwide in all oceans. In winter, 
humpback whales from waters off New England, Canada, Greenland, 
Iceland, and Norway migrate to mate and calve primarily in the West 
Indies, where spatial and genetic mixing among these groups occurs. For 
the humpback whale, NMFS defines a stock on the basis of feeding 
location, i.e., Gulf of Maine. However, our reference to humpback 
whales in this document refers to any individuals of the species that 
are found in the specific geographic region. These individuals may be 
from the same breeding population (e.g., West Indies breeding 
population of humpback whales) but visit different feeding areas.
    Based on photo-identification only 39 percent of individual 
humpback whales observed along the mid- and south Atlantic U.S. coast 
are from the Gulf of Maine stock (Barco et al., 2002). Therefore, the 
SAR abundance estimate underrepresents the relevant population, i.e., 
the West Indies breeding population.
    Prior to 2016, humpback whales were listed under the ESA as an 
endangered species worldwide. Following a 2015 global status review 
(Bettridge et al., 2015), NMFS established 14 DPSs with different 
listing statuses (81 FR 62259; September 8, 2016) pursuant to the ESA. 
The West Indies Distinct Population Segment (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. 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.
    Humpback whales are the only large cetaceans that are likely to 
occur in the project area and could be found there at any time of the 
year. There has been a decline in whale sightings in the peak

[[Page 56907]]

months since 2016/17; the distribution of whale sightings occur most 
frequently in the month of January through March (Aschettino et al., 
2020).
    There have been 33 humpback whale strandings recorded in Virginia 
between 1988 and 2013. Most of these strandings were reported from 
ocean facing beaches, but 11 were also within the Chesapeake Bay (Barco 
and Swingle, 2014). Strandings occurred in all seasons, but were most 
common in the spring. Since January 2016, elevated humpback whale 
mortalities have occurred along the Atlantic coast from Maine through 
Florida. The event has been declared an Unusual Mortality Event (UME) 
with 150 strandings recorded, 7 of which occurred in or near the mouth 
of the Chesapeake Bay. More detailed information is available at: 
https://www.fisheries.noaa.gov/national/marine-life-distress/2016-2021-humpback-whale-unusual-mortality-event-along-atlantic-coast. Three 
previous UMEs involving humpback whales have occurred since 2000, in 
2003, 2005, and 2006.
    Humpback whales use the mid-Atlantic as a migratory pathway to and 
from the calving/mating grounds, but it may also be an important winter 
feeding area for juveniles. Since 1989, observations of juvenile 
humpbacks in the mid-Atlantic have been increasing during the winter 
months, peaking from January through March (Swingle et al., 1993). 
Biologists theorize that non-reproductive animals may be establishing a 
winter feeding range in the mid-Atlantic since they are not 
participating in reproductive behavior in the Caribbean.

Bottlenose Dolphin

    The bottlenose dolphin occurs in temperate and tropical oceans 
throughout the world (Blaylock 1985). In the western Atlantic Ocean 
there are two distinct morphotypes of bottlenose dolphins, an offshore 
type that occurs along the edge of the continental shelf as well as an 
inshore type. The inshore morphotype can be found along the entire 
United States coast from New York to the Gulf of Mexico, and typically 
occurs in waters less than 20 meters deep (NOAA Fisheries 2016a). 
Bottlenose dolphins found in Virginia are representative primarily of 
either the northern migratory coastal stock, southern migratory coastal 
stock, or the Northern North Carolina Estuarine System Stock (NNCES).
    The northern migratory coastal stock is best defined by its 
distribution during warm water months when the stock occupies coastal 
waters from the shoreline to approximately the 20 m isobath between 
Assateague, Virginia, and Long Island, New York (Garrison et al., 
2017). The stock migrates in late summer and fall and, during cold 
water months (best described by January and February), occupies coastal 
waters from approximately Cape Lookout, North Carolina, to the North 
Carolina/Virginia border. Historically, common bottlenose dolphins have 
been rarely observed during cold water months in coastal waters north 
of the North Carolina/Virginia border, and their northern distribution 
in winter appears to be limited by water temperatures. Overlap with the 
southern migratory coastal stock in coastal waters of northern North 
Carolina and Virginia is possible during spring and fall migratory 
periods, but the degree of overlap is unknown and it may vary depending 
on annual water temperature (Garrison et al., 2016). When the stock has 
migrated in cold water months to coastal waters from just north of Cape 
Hatteras, North Carolina, to just south of Cape Lookout, North 
Carolina, it overlaps spatially with the Northern North Carolina 
Estuarine System (NNCES) Stock (Garrison et al., 2017).
    The southern migratory coastal stock migrates seasonally along the 
coast between North Carolina and northern Florida (Garrison et al., 
2017). During January-March, the southern migratory coastal stock 
appears to move as far south as northern Florida. During April-June, 
the stock moves back north past Cape Hatteras, North Carolina, where it 
overlaps, in coastal waters, with the NNCES stock (in waters <=1 km 
from shore). During the warm water months of July-August, the stock is 
presumed to occupy coastal waters north of Cape Lookout, North 
Carolina, to Assateague, Virginia, including the Chesapeake Bay.
    The NNCES stock is best defined as animals that occupy primarily 
waters of the Pamlico Sound estuarine system (which also includes Core, 
Roanoke, and Albemarle sounds, and the Neuse River) during warm water 
months (July-August). Members of this stock also use coastal waters 
(<=1 km from shore) of North Carolina from Beaufort north to Virginia 
Beach, Virginia, including the lower Chesapeake Bay. A community of 
NNCES dolphins are likely year-round Bay residents (Eric Patterson, 
pers. communication).

Harbor Porpoise

    The harbor porpoise is typically found in colder waters in the 
northern hemisphere. In the western North Atlantic Ocean, harbor 
porpoises range from Greenland to as far south as North Carolina (Barco 
and Swingle, 2014). They are commonly found in bays, estuaries, and 
harbors less than 200 meters deep (NOAA Fisheries, 2016c). Harbor 
porpoises in the United States are made up of the Gulf of Maine/Bay of 
Fundy stock. Gulf of Maine/Bay of Fundy stock are concentrated in the 
Gulf of Maine in the summer, but are widely dispersed from Maine to New 
Jersey in the winter. South of New Jersey, harbor porpoises occur at 
lower densities. Migrations to and from the Gulf of Maine do not follow 
a defined route (NOAA Fisheries, 2016c).
    Harbor porpoise occur seasonally in the winter and spring in small 
numbers near the project area. Strandings occur primarily on ocean 
facing beaches, but they occasionally travel into the Chesapeake Bay to 
forage and could occur in the project area (Barco and Swingle, 2014). 
Since 1999, stranding incidents have ranged widely from a high of 40 in 
1999 to 2 in 2011, 2012, and 2016 (Barco et al., 2017). In most areas, 
harbor porpoise occur in small groups of just a few individuals.

Harbor Seal

    The harbor seal occurs in arctic and temperate coastal waters 
throughout the northern hemisphere, including on both the east and west 
coasts of the United States. On the east coast, harbor seals can be 
found from the Canadian Arctic down to Georgia (Blaylock, 1985). Harbor 
seals occur year-round in Canada and Maine and seasonally (September-
May) from southern New England to New Jersey (NOAA Fisheries, 2016d). 
The range of harbor seals appears to be shifting as they are regularly 
reported further south than they were historically. In recent years, 
they have established haulout sites in the Chesapeake Bay including on 
the portal islands of the CBBT (Rees et al., 2016, Jones et al., 2018).
    Harbor seals are the most common seal in Virginia (Barco and 
Swingle, 2014). They can be seen resting on the rocks around the portal 
islands of the CBBT from December through April. Seal observation 
surveys conducted at the CBBT recorded 112 seals during the 2014/2015 
season, 184 seals during the 2015/2016 season, 308 seals in the 2016/
2017 season and 340 seals during the 2017/2018 season. They are 
primarily concentrated north of the project area at Portal Island No. 3 
(Rees et al 2016; Jones et al. 2018).
    Harbor seals are central-place foragers (Orians and Pearson, 1979) 
and tend to exhibit strong site fidelity within season and across 
years, generally forage close to haulout sites, and repeatedly visit 
specific foraging areas (Suryan and Harvey, 1998; Thompson et al., 
1998). Harbor seals tend to forage at night and

[[Page 56908]]

haul out during the day with a peak in the afternoon between 1 p.m. and 
4 p.m. (London et al., 2001).

Gray Seal

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

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Current data indicate that not all marine 
mammal species have equal hearing capabilities (e.g., Richardson et 
al., 1995; Wartzok and Ketten, 1999; Au and Hastings, 2008). To reflect 
this, Southall et al. (2007) recommended that marine mammals be divided 
into functional hearing groups based on directly measured or estimated 
hearing ranges on the basis of available behavioral response data, 
audiograms derived using auditory evoked potential techniques, 
anatomical modeling, and other data. Note that no direct measurements 
of hearing ability have been successfully completed for mysticetes 
(i.e., low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibel (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their associated hearing ranges are provided in Table 4.

                  Table 4--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. 
Humpback whales are in the low-frequency hearing group, bottlenose 
dolphins are in the mid-frequency hearing group, harbor porpoises are 
in the high frequency hearing group, and both harbor and gray seals are 
in the phocid group.

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.
    Acoustic effects on marine mammals during the specified activity 
can occur from impact and vibratory pile driving and removal and DTH. 
The effects of underwater noise from CTJV's proposed activities have 
the potential to result in Level A or Level B harassment of marine 
mammals in the action area.

Description of Sound Sources

    The marine soundscape is comprised of both ambient and 
anthropogenic sounds. Ambient sound is defined as the all-encompassing 
sound in a given place and is usually a composite of sound from many 
sources both near and far (ANSI 1994, 1995). The sound level of an area 
is defined by the total acoustical energy being generated by known and 
unknown sources. These sources may include physical (e.g., waves, wind, 
precipitation, earthquakes, ice, atmospheric sound), biological (e.g., 
sounds produced by marine mammals, fish, and invertebrates), and 
anthropogenic sound (e.g., vessels, dredging, aircraft, construction).
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which

[[Page 56909]]

comprise ``ambient'' or ``background'' sound--depends not only on the 
source levels (as determined by current weather conditions and levels 
of biological and shipping activity) but also on the ability of sound 
to propagate through the environment. In turn, sound propagation is 
dependent on the spatially and temporally varying properties of the 
water column and sea floor, and is frequency-dependent. As a result of 
the dependence on a large number of varying factors, ambient sound 
levels can be expected to vary widely over both coarse and fine spatial 
and temporal scales. Sound levels at a given frequency and location can 
vary by 10-20 dB from day to day (Richardson et al., 1995). The result 
is that, depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    In-water construction activities associated with the project would 
include impact and vibratory pile driving and removal and DTH. The 
sounds produced by these activities fall into one of two general sound 
types: impulsive and non-impulsive. Impulsive sounds (e.g., explosions, 
gunshots, sonic booms, impact pile driving) are typically transient, 
brief (less than 1 second), broadband, and consist of high peak sound 
pressure with rapid rise time and rapid decay (ANSI, 1986; NIOSH, 1998; 
ANSI, 2005; NMFS, 2018). Non-impulsive sounds (e.g., machinery 
operations such as drilling or dredging, vibratory pile driving, 
underwater chainsaws, pile clippers, and active sonar systems) can be 
broadband, narrowband or tonal, brief or prolonged (continuous or 
intermittent), and typically do not have the high peak sound pressure 
with raid rise/decay time that impulsive sounds do (ANSI 1995; NIOSH 
1998; NMFS 2018). 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).
    Three types of pile hammers would be used on this project: impact, 
vibratory, and DTH. Impact hammers operate by repeatedly dropping and/
or pushing a heavy piston onto a pile to drive the pile into the 
substrate. Sound generated by impact hammers is characterized by rapid 
rise times and high peak levels, a potentially injurious combination 
(Hastings and Popper, 2005). Vibratory hammers install piles by 
vibrating them and allowing the weight of the hammer to push them into 
the sediment. Vibratory hammers produce significantly less sound than 
impact hammers. Peak Sound pressure Levels (SPLs) may be 180 dB or 
greater, but are generally 10 to 20 dB lower than SPLs generated during 
impact pile driving of the same-sized pile (Oestman et al., 2009). Rise 
time is slower, reducing the probability and severity of injury, and 
sound energy is distributed over a greater amount of time (Nedwell and 
Edwards, 2002; Carlson et al., 2005).
    A DTH hammer is essentially a drill bit that drills through the 
bedrock using a rotating function like a normal drill, in concert with 
a hammering mechanism operated by a pneumatic (or sometimes hydraulic) 
component integrated into to the DTH hammer to increase speed of 
progress through the substrate (i.e., it is similar to a ``hammer 
drill'' hand tool). Rock socketing involves using DTH equipment to 
create a hole in the bedrock inside which the pile is placed to give it 
lateral and longitudinal strength. The sounds produced by the DTH 
method contain both a continuous non-impulsive component from the 
drilling action and an impulsive component from the hammering effect. 
Therefore, we treat DTH systems as both impulsive and continuous, non-
impulsive sound source types simultaneously.
    The likely or possible impacts of CTJV's proposed activity on 
marine mammals could involve both non-acoustic and acoustic stressors. 
Potential non-acoustic stressors could result from the physical 
presence of the equipment, vessels, and personnel; however, any impacts 
to marine mammals are expected to primarily be acoustic in nature. 
Acoustic stressors include effects of heavy equipment operation during 
pile installation and removal.

Acoustic Impacts

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving equipment is the primary means by which 
marine mammals may be harassed from the CTJV's specified activity. In 
general, animals exposed to natural or anthropogenic sound may 
experience physical and psychological effects, ranging in magnitude 
from none to severe (Southall et al., 2007). Generally, exposure to 
pile driving and removal and other construction noise has the potential 
to result in auditory threshold shifts and behavioral reactions (e.g., 
avoidance, temporary cessation of foraging and vocalizing, changes in 
dive behavior). Exposure to anthropogenic noise can also lead to non-
observable physiological responses such an increase in stress hormones. 
Additional noise in a marine mammal's habitat can mask acoustic cues 
used by marine mammals to carry out daily functions such as 
communication and predator and prey detection. The effects of pile 
driving and demolition noise on marine mammals are dependent on several 
factors, including, but not limited to, sound type (e.g., impulsive vs. 
non-impulsive), the species, age and sex class (e.g., adult male vs. 
mom with calf), duration of exposure, the distance between the pile and 
the animal, received levels, behavior at time of exposure, and previous 
history with exposure (Wartzok et al., 2004; Southall et al., 2007). 
Here we discuss physical auditory effects (threshold shifts) followed 
by behavioral effects and potential impacts on habitat.
    NMFS defines a noise-induced threshold shift (TS) as a change, 
usually an increase, in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS, 2018). The amount of 
threshold shift is customarily expressed in dB. A TS can be permanent 
or temporary. As described in NMFS (2018), there are numerous factors 
to consider when examining the consequence of TS, including, but not 
limited to, the signal temporal pattern (e.g., impulsive or non-
impulsive), likelihood an individual would be exposed for a long enough 
duration or to a high enough level to induce a TS, the magnitude of the 
TS, time to recovery (seconds to minutes or hours to days), the 
frequency range of the exposure (i.e., spectral content), the hearing 
and vocalization frequency range of the exposed species relative to the 
signal's frequency spectrum (i.e., how animal uses sound within the 
frequency band of the signal; e.g., Kastelein et al., 2014), and the 
overlap between the animal and the source (e.g., spatial, temporal, and 
spectral).
    Permanent Threshold Shift (PTS)--NMFS defines PTS as a permanent, 
irreversible increase in the threshold of audibility at a specified 
frequency or portion of an individual's hearing range above a 
previously established reference level (NMFS 2018). Available data from 
humans and other terrestrial mammals indicate that a 40 dB threshold 
shift approximates PTS onset (see Ward et al., 1958, 1959; Ward, 1960; 
Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; Henderson and 
Hu, 2008). PTS levels for marine mammals are estimates, with the 
exception of a single study unintentionally inducing PTS in a harbor 
seal (Kastak et al., 2008), there are no empirical data measuring PTS 
in marine mammals, largely due to the fact

[[Page 56910]]

that, for various ethical reasons, experiments involving anthropogenic 
noise exposure at levels inducing PTS are not typically pursued or 
authorized (NMFS, 2018).
    Temporary Threshold Shift (TTS)--A temporary, reversible increase 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018). Based on data from cetacean TTS measurements (see 
Southall et al., 2007), a TTS of 6 dB is considered the minimum 
threshold shift clearly larger than any day-to-day or session-to-
session variation in a subject's normal hearing ability (Schlundt et 
al., 2000; Finneran et al., 2000, 2002). As described in Finneran 
(2016), marine mammal studies have shown the amount of TTS increases 
with cumulative sound exposure level (SELcum) in an 
accelerating fashion: At low exposures with lower SELcum, 
the amount of TTS is typically small and the growth curves have shallow 
slopes. At exposures with higher SELcum, the growth curves 
become steeper and approach linear relationships with the noise SEL.
    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 (similar to those discussed in auditory 
masking, below). For example, a marine mammal may be able to readily 
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that takes place during a time when the animal 
is traveling through the open ocean, where ambient noise is lower and 
there are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts. We note that reduced hearing sensitivity as 
a simple function of aging has been observed in marine mammals, as well 
as humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    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 five species of pinnipeds 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). The potential for TTS from impact pile driving 
exists. After exposure to playbacks of impact pile driving sounds (rate 
2760 strikes/hour) in captivity, mean TTS increased from 0 dB after 15 
minute exposure to 5 dB after 360 minute exposure; recovery occurred 
within 60 minutes (Kastelein et al., 2016). Additionally, the existing 
marine mammal TTS data come from a limited number of individuals within 
these species. No data are 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 Table 5 in 
NMFS (2018).
    Installing piles for this project requires impact pile driving. 
There would likely be pauses in activities producing the sound during 
each day. Given these pauses and that many marine mammals are likely 
moving through the action area and not remaining for extended periods 
of time, the potential for TS declines.
    Behavioral Harassment--Exposure to noise from pile driving and 
removal also has the potential to behaviorally disturb marine mammals. 
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).
    Disturbance may result in changing durations of surfacing and 
dives, number of blows per surfacing, or moving direction and/or speed; 
reduced/increased vocal activities; changing/cessation of certain 
behavioral activities (such as socializing or feeding); visible startle 
response or aggressive behavior (such as tail/fluke slapping or jaw 
clapping); avoidance of areas where sound sources are located. 
Pinnipeds may increase their haulout time, possibly to avoid in-water 
disturbance (Thorson and Reyff, 2006). 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., 2004; 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). 
In general, pinnipeds seem more tolerant of, or at least habituate more 
quickly to, potentially disturbing underwater sound than do cetaceans, 
and generally seem to be less responsive to exposure to industrial 
sound than most cetaceans. Please see Appendices B and C of Southall et 
al. (2007) for a review of studies involving marine mammal behavioral 
responses to sound.
    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.
    In 2016, the Alaska Department of Transportation and Public 
Facilities (ADOT&PF) documented observations of marine mammals during 
construction activities (i.e., pile driving) at the Kodiak Ferry Dock 
(see 80 FR 60636, October 7, 2015). In the marine mammal monitoring 
report for that project (ABR

[[Page 56911]]

2016), 1,281 Steller sea lions were observed within the estimated Level 
B harassment zone during pile driving or drilling (i.e., documented as 
potential take by Level B harassment). Of these, 19 individuals 
demonstrated an alert behavior, 7 were fleeing, and 19 swam away from 
the project site. All other animals (98 percent) were engaged in 
activities such as milling, foraging, or fighting and did not change 
their behavior. In addition, two sea lions approached within 20 m of 
active vibratory pile driving activities. Three harbor seals were 
observed within the disturbance zone during pile driving activities; 
none of them displayed disturbance behaviors. Fifteen killer whales and 
three harbor porpoise were also observed within the Level B harassment 
zone during pile driving. The killer whales were travelling or milling 
while all harbor porpoises were travelling. No signs of disturbance 
were noted for either of these species. Given the similarities in 
species, activities and habitat, we expect similar behavioral responses 
of marine mammals to the CTJV's specified activity. That is, 
disturbance, if any, is likely to be temporary and localized (e.g., 
small area movements).
    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), however 
distress is an unlikely result of this project based on observations of 
marine mammals during previous, similar projects in the area.
    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). 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., pile driving, 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. Masking of natural sounds can result when human activities 
produce high levels of background sound at frequencies important to 
marine mammals. Conversely, if the background level of underwater sound 
is high (e.g., on a day with strong wind and high waves), an 
anthropogenic sound source would not be detectable as far away as would 
be possible under quieter conditions and would itself be masked. The 
San Francisco area contains active military and commercial shipping, 
ferry operations, as well as numerous recreational and other commercial 
vessel and background sound levels in the area are already elevated.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with pile driving 
and removal that have the potential to cause behavioral harassment, 
depending on their distance from pile driving activities. Cetaceans are 
not expected to be exposed to airborne sounds that would result in 
harassment as defined under the MMPA.
    Airborne noise would primarily be an issue for pinnipeds that are 
swimming or hauled out near the project site within the range of noise 
levels elevated above the acoustic criteria. We recognize that 
pinnipeds in the water could be exposed to airborne sound that may 
result in behavioral harassment when looking with their heads above 
water. Most likely, airborne sound would cause behavioral responses 
similar to those discussed above in relation to underwater sound. For 
instance, anthropogenic sound could cause hauled out pinnipeds to 
exhibit changes in their normal behavior, such as reduction in 
vocalizations, or cause them to temporarily abandon the area and move 
further from the source. However, these animals would likely previously 
have been `taken' because of exposure to underwater sound above the 
behavioral harassment thresholds, which are generally larger than those 
associated with airborne sound. Thus, the behavioral harassment of 
these animals is already accounted for in these estimates of potential 
take. Therefore, we do not believe that authorization of incidental 
take

[[Page 56912]]

resulting from airborne sound for pinnipeds is warranted, and airborne 
sound is not discussed further here.

Marine Mammal Habitat Effects

    CTJV's construction activities could have localized, temporary 
impacts on marine mammal habitat and their prey by increasing in-water 
sound pressure levels and slightly decreasing water quality. Increased 
noise levels may affect acoustic habitat (see masking discussion above) 
and adversely affect marine mammal prey in the vicinity of the project 
area (see discussion below). During DTH, impact and vibratory pile 
driving or removal, elevated levels of underwater noise would ensonify 
the project area where both fishes and mammals occur and could affect 
foraging success. Additionally, marine mammals may avoid the area 
during construction, however, displacement due to noise is expected to 
be temporary and is not expected to result in long-term effects to the 
individuals or populations. Construction activities are of short 
duration and would likely have temporary impacts on marine mammal 
habitat through increases in underwater and airborne sound.
    A temporary and localized increase in turbidity near the seafloor 
would occur in the immediate area surrounding the area where piles are 
installed or removed. In general, turbidity associated with pile 
installation is localized to about a 25-foot (7.6-m) radius around the 
pile (Everitt et al., 1980). The sediments of the project site are 
sandy and will settle out rapidly when disturbed. Cetaceans are not 
expected to be close enough to the pile driving areas to experience 
effects of turbidity, and any pinnipeds could avoid localized areas of 
turbidity. Local strong currents are anticipated to disburse any 
additional suspended sediments produced by project activities at 
moderate to rapid rates depending on tidal stage. Therefore, we expect 
the impact from increased turbidity levels to be discountable to marine 
mammals and do not discuss it further.

In-Water Construction Effects on Potential Foraging Habitat

    The area likely impacted by the project is relatively small 
compared to the available habitat Chesapeake Bay and the Atlantic and 
does not include any Biologically Important Areas or other habitat of 
known importance. The area is highly influenced by anthropogenic 
activities. The total seafloor area affected by pile installation and 
removal is a small area compared to the vast foraging area available to 
marine mammals in the area. At best, the impact area provides marginal 
foraging habitat for marine mammals and fishes. Furthermore, pile 
driving and removal at the project site would not obstruct movements or 
migration of marine mammals.
    Avoidance by potential prey (i.e., fish) of the immediate area due 
to the temporary loss of this foraging habitat is also possible. The 
duration of fish avoidance of this area after pile driving stops is 
unknown, but a rapid return to normal recruitment, distribution and 
behavior is anticipated. 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.
    In-water Construction Effects on Potential 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. 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 and Mann, 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. Additional studies 
have documented effects of pile driving on fish; several are based on 
studies in support of large, multiyear bridge construction projects 
(e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 2009). 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).
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (Halvorsen et al., 2012b; Casper et al., 2013).
    The most likely impact to fish from pile driving and removal and 
construction activities at the project area would be temporary 
behavioral avoidance of the area. The duration of fish avoidance of 
this area after pile driving stops is unknown, but a rapid return to 
normal recruitment, distribution and behavior is anticipated.
    Construction activities, in the form of increased turbidity, have 
the potential to adversely affect forage fish in the project area. 
Forage fish form a significant prey base for many marine mammal species 
that occur in the project area. Increased turbidity is expected to 
occur in the immediate vicinity (on the order of 10 feet (3 m) or less) 
of construction activities. However, suspended sediments and 
particulates are expected to dissipate quickly within a single tidal 
cycle. Given the limited area affected and high tidal dilution rates 
any effects on forage fish are expected to be minor or negligible. 
Finally, exposure to turbid waters from construction activities is not 
expected to be different from the current exposure; fish and marine 
mammals in Chesapeake are routinely exposed to substantial levels of 
suspended sediment from natural and anthropogenic sources.

[[Page 56913]]

    In summary, given the short daily duration of sound associated with 
individual pile driving events and the relatively small areas being 
affected, pile driving activities associated with the proposed action 
are not likely to have a permanent, adverse effect on any fish habitat, 
or populations of fish species. 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. Thus, 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. Further, 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.

Estimated Take

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform both 
NMFS' consideration of ``small numbers'' and the negligible impact 
determination.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., vibratory or impact pile driving and 
DTH) have the potential to result in disruption of behavioral patterns 
for individual marine mammals. There is also some potential for 
auditory injury (Level A harassment) to result for pinnipeds and harbor 
porpoise because predicted auditory injury zones are larger. The 
proposed mitigation and monitoring measures are expected to minimize 
the severity of the taking to the extent practicable.
    As described previously, no mortality is anticipated or proposed to 
be authorized for this activity. Below we describe how the take is 
estimated.
    Generally speaking, we estimate take by considering: (1) Acoustic 
thresholds above which 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). Due to the lack of 
marine mammal density data available for this location, NMFS relied on 
local occurrence data and group size to estimate take for some species. 
Below, we describe the factors considered here in more detail and 
present the proposed take estimate.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment for non-explosive sources--Though significantly 
driven by received level, the onset of behavioral disturbance from 
anthropogenic noise exposure is also informed to varying degrees by 
other factors related to the source (e.g., frequency, predictability, 
duty cycle), the environment (e.g., bathymetry), and the receiving 
animals (hearing, motivation, experience, demography, behavioral 
context) and can be difficult to predict (Southall et al., 2007, 
Ellison et al., 2012). Based on what the available science indicates 
and the practical need to use a threshold based on a factor that is 
both predictable and measurable for most activities, NMFS uses a 
generalized acoustic threshold based on received level to estimate the 
onset of behavioral harassment. NMFS predicts that marine mammals are 
likely to be behaviorally harassed in a manner we consider Level B 
harassment when exposed to underwater anthropogenic noise above 
received levels of 120 dB re 1 microPascal ([mu]Pa) (root mean square 
(rms)) for continuous (e.g., vibratory pile-driving) and above 160 dB 
re 1 [mu]Pa (rms) for non-explosive impulsive (e.g., impact pile 
driving) or intermittent (e.g., scientific sonar) sources.
    CTJV's proposed activity includes the use of continuous (vibratory 
hammer and DTH) and impulsive (impact pile-driving) sources, and 
therefore the 120 and 160 dB re 1 [mu]Pa (rms) thresholds are 
applicable. However, CTJV recorded ambient sounds at the project site 
for over two weeks in 2019 (https://media.fisheries.noaa.gov/dam-migration/ctjvthimbleshoals_final_ssv_report_opr1_3-23.pdf) and 
established that median ambient sounds levels were 122.78 dB. We have 
therefore agreed to use this value as the threshold for the continuous 
sources.
    Level A harassment for non-explosive sources--NMFS' Technical 
Guidance for Assessing the Effects of Anthropogenic Sound on Marine 
Mammal Hearing (Version 2.0) (Technical Guidance, 2018) identifies dual 
criteria to assess auditory injury (Level A harassment) to five 
different marine mammal groups (based on hearing sensitivity) as a 
result of exposure to noise from two different types of sources 
(impulsive or non-impulsive). CTJV's activity includes the use of 
impulsive (impact pile-driving and DTH) and non-impulsive (vibratory 
hammer and DTH) sources.
    These thresholds are provided in Table 5. The references, analysis, 
and methodology used in the development of the thresholds are described 
in NMFS 2018 Technical Guidance, which may be accessed at https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.

                     Table 5--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.

[[Page 56914]]

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

Ensonified Area

    Here, 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 sound field in the project area is the existing background 
noise plus additional construction noise from the proposed project. 
Marine mammals are expected to be affected via sound generated by the 
primary components of the project (i.e., impact and vibratory pile 
driving, and DTH).
    In order to calculate distances to the Level A harassment and Level 
B harassment sound thresholds for the methods and piles being used in 
this project, NMFS used acoustic monitoring data from other locations 
to develop source levels for the various pile types, sizes and methods 
(Table 6). Based on monitoring the sound source levels for some piles 
with versus without a bubble curtain in prior years of this project it 
was determined that the bubble curtain system used for this project 
provided a 6 db reduction in near field sound levels (https://media.fisheries.noaa.gov/dam-migration/ctjvthimbleshoals_final_ssv_report_opr1_3-23.pdf) and we have agreed to 
apply this reduction in source levels for this proposed work.

                                      Table 6--Project Sound Source Levels
----------------------------------------------------------------------------------------------------------------
                                      Estimated noise levels
               Method                          (dB)                                 Source
----------------------------------------------------------------------------------------------------------------
DTH-impulsive.......................  164 SELss.............  Reyff & Heyvaert (2019).
DTH-non-impulsive...................  166 dB RMS............  Denes et al. (2016).
Impact..............................  204 Pk, 177 SEL *.....  Caltrans (2015) Table I.2.1.
Vibratory...........................  174 Pk, 164 RMS *.....  Caltrans (2015) Table I.2.2.
----------------------------------------------------------------------------------------------------------------
Note: SEL = single strike sound exposure level; RMS = root mean square.
* Source levels reduced by 6 dB to account for use of bubble curtain.

Level B Harassment Zones

    Transmission loss (TL) is the decrease in acoustic intensity as an 
acoustic pressure wave propagates out from a source. TL parameters vary 
with frequency, temperature, sea conditions, current, source and 
receiver depth, water depth, water chemistry, and bottom composition 
and topography. The general formula for underwater TL is:

TL = B * Log10 (R1/R2),

Where:

TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial measurement

    The recommended TL coefficient for most nearshore environments is 
the practical spreading value of 15. This value results in an expected 
propagation environment that would lie between spherical and 
cylindrical spreading loss conditions, which is the most appropriate 
assumption for CTJV's proposed activity in the absence of specific 
modelling.
    CTJV determined underwater noise would fall below the behavioral 
effects threshold of 160 dB RMS for impact driving at 136 m and the 
122.78 dB rms threshold for vibratory driving at 5,598 m (Table 7). 
Distances to the 122.78 threshold for the various combinations of 
simultaneous DTH, vibratory pile driving, and/or impact pile driving 
range from 7,609 to 14,061 m (Table 7). It should be noted that based 
on the bathymetry and geography of the project area, sound will not 
reach the full distance of the harassment isopleths in all directions 
(see Application Appendix A).

Level A Harassment Zones

    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 take by Level A harassment. 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

[[Page 56915]]

will qualitatively address the output where appropriate. For stationary 
sources such as pile driving or removal and DTH using any of the 
methods discussed above, NMFS User Spreadsheet predicts the closest 
distance at which, if a marine mammal remained at that distance the 
whole duration of the activity, it would not incur PTS. We used the 
User Spreadsheet to determine the Level A harassment isopleths. Inputs 
used in the User Spreadsheet or models are reported in Table 1 and the 
resulting isopleths are reported in Table 7 for each of the 
construction methods and scenarios.

                         Table 7--Level A and Level B Isopleths (meters) for Each Method
----------------------------------------------------------------------------------------------------------------
                                             Low-        Mid-        High-
        Method and piles per day           frequency   frequency   frequency    Phocids    Otariids     Level B
                                           cetaceans   cetaceans   cetaceans
----------------------------------------------------------------------------------------------------------------
DTH (3 per day).........................       1,226          44       1,460         656          48       7,609
DTH (6 per day).........................       1,946          70       2,318       1,042          76      12,060
Impact (4 per day)......................       1,002          36       1,194         537          39         136
Impact (6 per day)......................       1,313          47       1,564         703          52         136
Vibratory...............................           9           1          14           6           1       5,598
                                         ------------------------------------------------------------
Impact + DTH............................                Use zones for each source alone                    7,609
DTH + Vibratory.........................                         Use DTH zones                            10,344
Impact + Vibratory......................                       Use Impact zones                            5,598
Impact + DTH + DTH......................                Use zones for each source alone                   12,060
DTH + DTH + Vibratory...................                         Use DTH zones                            14,061
DTH + Vibratory + Impact................                         Use DTH zones                            10,344
Impact + Impact + DTH...................                Use zones for each source alone                    7,609
----------------------------------------------------------------------------------------------------------------

    Because CTJV will use multiple simultaneous methods we need to 
account for the effect of this on sound levels. When two non-impulsive 
continuous noise sources, such as vibratory hammers or DTH, have 
overlapping sound fields, there is potential for higher sound levels 
than for non-overlapping sources. In these cases, the sources may be 
considered additive and combined using the rules in Table 8. For 
addition of two simultaneous non-impulsive continuous sources, the 
difference between the two sound source levels (SSLs) is calculated, 
and if that difference is between 0 and 1 dB, 3 dB are added to the 
higher SSL; if difference is between 2 or 3 dB, 2 dB are added to the 
highest SSL; if the difference is between 4 to 9 dB, 1 dB is added to 
the highest SSL; and with differences of 10 or more dB, there is no 
addition.
    For simultaneous usage of three or more continuous sound sources, 
the three overlapping sources with the highest SSLs are identified. Of 
the three highest SSLs, the lower two are combined using the above 
rules, then the combination of the lower two is combined with the 
highest of the three. For example, with overlapping isopleths from 24-, 
36-, and 42-inch diameter steel pipe piles with SSLs of 161, 167, and 
168 dB rms respectively, the 24- and 36-inch would be added together; 
given that 167-161 = 6 dB, then 1 dB is added to the highest of the two 
SSLs (167 dB), for a combined noise level of 168 dB. Next, the newly 
calculated 168 dB is added to the 42-inch steel pile with SSL of 168 
dB. Since 168-168 = 0 dB, 3 dB is added to the highest value, or 171 dB 
in total for the combination of 24-, 36-, and 42-inch steel pipe piles 
(NMFS 2018b; WSDOT 2018).
    Simultaneous use of two or more impact hammers or DTH does not 
require this sort of source level additions on its own. For impact 
hammering or DTH, it is unlikely that the two (or more) hammers would 
strike at the same exact instant, and therefore, the sound source 
levels will not be adjusted regardless of the distance between the 
hammers.

                  Table 8--Rules for Combining Sound Levels Generated During Pile Installation
----------------------------------------------------------------------------------------------------------------
             Hammer types                 Difference in SSL          Level A zones            Level B zones
----------------------------------------------------------------------------------------------------------------
Non-impulsive, Impulsive.............  Any....................  Use impulsive zones....  Use largest zone.
Impulsive, Impulsive.................  Any....................  Use zones for each pile  Use zone for each pile
                                                                 size and number of       size.
                                                                 strikes.
Non-impulsive, Non-impulsive.........  0 or 1 dB..............  Add 3 dB to the higher   Add 3 dB to the higher
                                                                 source level.            source level.
                                       2 or 3 dB..............  Add 2 dB to the higher   Add 2 dB to the higher
                                                                 source level.            source level.
                                       4 to 9 dB..............  Add 1 dB to the higher   Add 1 dB to the higher
                                                                 source level.            source level.
                                       10 dB or more..........  Add 0 dB to the higher   Add 0 dB to the higher
                                                                 source level.            source level.
----------------------------------------------------------------------------------------------------------------

Marine Mammal Occurrence and Take Calculation and Estimation

    In this section we provide the information about the presence, 
density, or group dynamics of marine mammals that will inform the take 
calculations. Here we describe how the information provided above is 
brought together to produce a quantitative take estimate. A summary of 
proposed take is in Table 9.

Humpback Whale

    Density data for this species in the project vicinity do not exist. 
Populations in the mid-Atlantic have been estimated for humpback whales 
off the coast of New Jersey with a density of 0.000130/km\2\ (Whitt et 
al., 2015). In the Project area, a similar density may be expected. 
Aschettino et al. (2018) observed and tracked 12 individual humpback 
whales west of the CBBT. Based on these data, and the known movement of 
humpback whales from

[[Page 56916]]

November through April at the mouth of the Chesapeake Bay, and as used 
in the prior IHAs, CTJV is requesting and we are proposing take of a 
single humpback group every two months for the duration of in-water 
pile driving activities. There are 12 months of in-water construction 
anticipated during the proposed IHA. Using an average group size of two 
animals, pile driving activities over a 12-month period would result in 
12 takes of humpback whale by Level B harassment.
    No takes by Level A harassment are expected or proposed because we 
expect CTJV will effectively shutdown for low-frequency whales 
including humpbacks at the full extent of the Level A harassment zones.

Bottlenose Dolphin

    In the previous IHA for this project we used seasonal density 
values documented by Engelhaupt et al. (2016). The Level B harassment 
area for each pile and driving type was multiplied by the appropriate 
seasonal density and the anticipated number of days of a specific 
activity per month number to derive a total number of takes for each 
construction project component. We use the same approach here. The 
number of calculated takes for the project is 86,656 (Table 10). There 
is insufficient information on relative abundance to apportion the 
takes precisely to the three stocks present in the area. We use the 
same approach used in the prior IHAs as well as in the nearby Hampton 
Roads Bridge and Tunnel project (86 FR 17458; April 2, 2021). Given 
that most of the NNCES stock are found in the Pamlico Sound estuarine 
system, NMFS will assume that no more than 250 of the authorized takes 
will be from this stock. Since members of the northern migratory 
coastal and southern migratory coastal stocks are thought to occur in 
or near the Bay in greater numbers, we will conservatively assume that 
no more than half of the remaining animals will accrue to either of 
these stocks. Additionally, a subset of these takes would likely be 
comprised of Chesapeake Bay resident dolphins, although the size of 
that population is unknown.
    No takes by Level A harassment are expected or proposed because we 
expect CTJV will effectively shutdown for bottlenose dolphins at the 
full extent of the Level A harassment zones.

Harbor Porpoise

    Density data for this species in the project vicinity do not exist. 
Given that harbor porpoises are uncommon in the project area, this 
exposure analysis (as we did for the prior IHAs) assumes that there is 
a porpoise sighting once during every two months of operations which 
would equate to six sightings during the year. Assuming an average 
group size of two (Hansen et al., 2018; Elliser et al., 2018) results 
in a total of 12 estimated takes of porpoises over a year.
    Harbor porpoises are members of the high-frequency hearing group 
which have Level A harassment isopleths as large as 2,318 m during DTH 
installation of 6 piles per day. In the previous IHA the shutdown zone 
was set at 100 m since harbor porpoises are cryptic, were thought to be 
somewhat common in the project area and are known to approach the 
shoreline. There was concern there would be excessive shutdowns that 
would extend the project and days of exposure of marine mammals to 
sound if the zones were larger. However, monitoring data to date 
suggests we can increase the shutdown zone to 200 m and still avoid an 
impracticable number of shutdowns. Therefore, we are proposing to 
implement a 200 m shutdown zone as a mitigation measure. Given the 
relatively large Level A harassment zones during impact driving and 
DTH, NMFS assumed in the previous IHAs that 40 percent of estimated 
porpoise takes would be by Level A harassment. The monitoring data on 
harbor porpoise take to date do not contradict this expectation. We 
therefore continue to assume this percentage, resulting in five 
proposed takes of porpoises by Level A harassment and seven takes by 
Level B harassment.

Harbor Seal

    With new data on harbor seals since the initial IHAs, we are 
altering our estimation method for this species. The new method also 
aligns with what we have used in other recent nearby projects. The 
number of harbor seals expected to be present in the PTST project area 
was estimated using survey data for in-water and hauled out seals 
collected by the United States Navy at the portal islands from November 
2014 through 2019 (Rees et al., 2016; Jones et al., 2020). The survey 
showed a daily average seal count of 13.6. We rounded this up to 14 
seals per day We multiplied that number by 95 in-water work days on 
Portal Island 1 and 111 work days on Portal Island 2 (the number of 
days of in-water activities when the seals are present, December to 
May) to estimate 2,884 takes of harbor seals.
    The largest Level A harassment isopleth for phocid species is 1,042 
meters which would occur during DTH of 6 large holes per day. In the 
previous IHA the shutdown zone was set at 15 m since seals are common 
in the project area and are known to approach the shoreline. There was 
concern there would be excessive shutdowns that would extend the 
project and days of exposure of marine mammals to sound if the zones 
were larger. However, monitoring data to date suggests we can increase 
the shutdown zone to 150 m and still avoid an impracticable number of 
shutdowns. Therefore, we are proposing to implement a shutdown zone of 
150 m for harbor seals. As discussed above for harbor porpoises we 
assume that 40 percent of the exposed seals will occur within the Level 
A harassment zone and the remaining affected seals would result in 
Level B harassment takes. Therefore, NMFS is proposing to authorize 
1,154 takes by Level A harassment and 1,730 takes by Level B 
harassment.

Gray Seal

    The number of gray seals expected to be present at the PTST project 
area was estimated using survey data collected by the U.S. Navy at the 
portal islands from 2014 through 2018 (Rees et al., 2016; Jones et al., 
2018). One seal was observed in February of 2015 and one seal was 
recorded in February of 2016, while no seals were observed at any other 
time. So the February rate of seal per day was estimated at 1.6. We 
rounded this to 2 animals per day and multiplied by the number of 
expected work days in February (20) to arrive at an estimate of 40 
takes of gray seals per year.
    The largest Level A harassment isopleth for phocid species is 1,042 
meters which would occur during DTH of 6 large holes per day. In the 
previous IHA the shutdown zone was set at 15 m since seals are common 
in the project area and are known to approach the shoreline. There was 
concern there would be excessive shutdowns that would extend the 
project and days of exposure of marine mammals to sound if the zones 
were larger. However, monitoring data to date suggests we can increase 
the shutdown zone to 150 m and still avoid an impracticable number of 
shutdowns. Therefore, we are proposing to implement a shutdown zone of 
150 m for gray seals. As above we estimate 40 percent of these takes 
could be by Level A harassment, so we propose to authorize 24 Level B 
harassment takes and 16 Level A harassment takes for gray seals.

[[Page 56917]]



   Table 9--Proposed Authorized Amount of Taking, by Level A Harassment and Level B Harassment, by Species and
                                       Stock and Percent of Take by Stock
----------------------------------------------------------------------------------------------------------------
                                                                             Level A      Level B     Percent of
                Common name                             Stock               harassment   harassment     stock
----------------------------------------------------------------------------------------------------------------
Humpback whale............................  Gulf of Maine................            0           12          0.9
Harbor Porpoise...........................  Gulf of Maine/Bay of Fundy...            5            7         <0.1
Bottlenose dolphin........................  WNA Coastal, Northern                    0       43,203          651
                                             Migratory.
Bottlenose dolphin........................  WNA Coastal, Northern                    0       43,203          651
                                             Migratory.
Bottlenose dolphin........................  NNCES........................            0          250         30.4
Harbor seal...............................  Western North Atlantic.......        1,154        1,730          3.8
Gray seal.................................  Western North Atlantic.......           16           24         <0.1
----------------------------------------------------------------------------------------------------------------


                    Table 10--Data To Estimate Level B Harassment Take of Bottlenose Dolphins
----------------------------------------------------------------------------------------------------------------
                                                                                             Level B
             Months                         Nov.     Dec.-    March-     June-     Sept.-      area     Dolphin
                                                     Feb.       May      Aug.       Oct.     (km\2\)      take
----------------------------------------------------------------------------------------------------------------
Dolphin Density/km\2\..........   Island     3.88      0.63         1      3.55      3.88   .........  .........
Impact + DTH...................        1       17        40        16         4         0         136     16,507
Impact + DTH...................        2        0         3         7        50        38         147     46,766
DTH + Vibratory................        1        2         4         1         1         0         218      3,235
DTH + Vibratory................        2        0         0         1         2         2         250      3,966
Impact + Vibratory.............        1        2         4         1         1         0          80      1,188
Impact + Vibratory.............        2        0         0         1         2         2          79      1,176
DTH + DTH + Impact.............    1 & 2        0         4        13         1         0         323      6,161
DTH + DTH + Vibratory..........    1 & 2        0         1         5         0         0         402      2,264
DTH + Vibratory + Impact.......    1 & 2        0         2         5         1         0         255      2,181
Impact + Impact + DTH..........    1 & 2        0         5        13         1         0         163      3,212
----------------------------------------------------------------------------------------------------------------
Note: Take is calculated by multiplying the density for a given time by the Area of the Level B harassment zone
  and the number of days of work (found in the main cells of the table). See more detailed table with monthly
  totals in Table 16 of the application.

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses (latter not applicable for this action). NMFS 
regulations require applicants for incidental take authorizations to 
include information about the availability and feasibility (economic 
and technological) of equipment, methods, and manner of conducting the 
activity or other means of effecting the least practicable adverse 
impact upon the affected species or stocks and their habitat (50 CFR 
216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, we 
carefully consider two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure will be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    The following mitigation measures are proposed in the IHA:
     Avoid direct physical interaction with marine mammals 
during construction activity. If a marine mammal comes within 10 m of 
such activity, operations must cease and vessels must reduce speed to 
the minimum level required to maintain steerage and safe working 
conditions;
     Conduct training between construction supervisors and 
crews and the marine mammal monitoring team and relevant CTJV staff 
prior to the start of all pile driving and DTH activity and when new 
personnel join the work, so that responsibilities, communication 
procedures, monitoring protocols, and operational procedures are 
clearly understood;
     Pile driving activity must be halted upon observation of 
either a species for which incidental take is not authorized or a 
species for which incidental take has been authorized but the 
authorized number of takes has been met, entering or within the 
harassment zone;
     CTJV will establish and implement the shutdown zones 
indicated in Table 11. The purpose of a shutdown zone is generally to 
define an area within which shutdown of the activity would occur upon 
sighting of a marine mammal (or in anticipation of an animal entering 
the defined area). Shutdown zones typically vary based on the activity 
type and marine mammal hearing group.
     Employ Protected Species Observers (PSOs) and establish 
monitoring locations as described in the Marine Mammal Monitoring Plan 
and Section 5 of the IHA. The Holder must monitor the project area to 
the maximum extent possible based on the required number of PSOs, 
required monitoring locations, and environmental conditions. For all 
pile driving and removal at least one PSO must be used. The PSO will be 
stationed as close to the activity as possible;

[[Page 56918]]

     The placement of the PSOs during all pile driving and 
removal and DTH activities will ensure that the entire shutdown zone is 
visible during pile installation. Should environmental conditions 
deteriorate such that marine mammals within the entire shutdown zone 
will not be visible (e.g., fog, heavy rain), pile driving and removal 
must be delayed until the PSO is confident marine mammals within the 
shutdown zone could be detected;
     Monitoring must take place from 30 minutes prior to 
initiation of pile driving activity through 30 minutes post-completion 
of pile driving activity. Pre-start clearance monitoring must be 
conducted during periods of visibility sufficient for the lead PSO to 
determine the shutdown zones clear of marine mammals. Pile driving may 
commence following 30 minutes of observation when the determination is 
made;
     If pile driving is delayed or halted due to the presence 
of a marine mammal, the activity may not commence or resume until 
either the animal has voluntarily exited and been visually confirmed 
beyond the shutdown zone or 15 minutes have passed without re-detection 
of the animal;
     CTJV must use soft start techniques when impact pile 
driving. Soft start requires contractors to provide an initial set of 
three strikes at reduced energy, followed by a 30-second waiting 
period, then two subsequent reduced-energy strike sets. A soft start 
must be implemented at the start of each day's impact pile driving and 
at any time following cessation of impact pile driving for a period of 
30 minutes or longer;
     Use a bubble curtain during impact and vibratory pile 
driving and DTH in water depths greater than 3 m (10 ft) and ensure 
that it is operated as necessary to achieve optimal performance, and 
that no reduction in performance may be attributable to faulty 
deployment. At a minimum, CTJV must adhere to the following performance 
standards: The bubble curtain must distribute air bubbles around 100 
percent of the piling circumference for the full depth of the water 
column. The lowest bubble ring must be in contact with the substrate 
for the full circumference of the ring, and the weights attached to the 
bottom ring shall ensure 100 percent substrate contact. No parts of the 
ring or other objects shall prevent full substrate contact. Air flow to 
the bubblers must be balanced around the circumference of the pile. For 
work with interlocking pipe piles for the berm construction a special 
3-sided bubble curtain will be used (see Application Appendix A).

                                Table 11--Shutdown Zones (meters) for Each Method
----------------------------------------------------------------------------------------------------------------
                                            Low-frequency     Mid-frequency    High-frequency
          Method and piles/day                cetaceans         cetaceans         cetaceans          Phocids
----------------------------------------------------------------------------------------------------------------
DTH (3/day).............................             1,230                50               200               150
DTH (6/day).............................             1,950                70               200               150
Impact (4/day)..........................             1,010                40               200               150
Impact (6/day)..........................             1,320                50               200               150
Vibratory (4/day).......................                20                10                20                10
Impact + DTH............................
DTH + Vibratory.........................             1,230                50               200               150
Impact + Vibratory......................             1,320                50               200               150
Impact + DTH + DTH......................             1,320                50               200               150
DTH + DTH + Vibratory...................             1,950                70               200             1,050
DTH + Vibratory + Impact................             1,320                50               200               710
Impact + Impact + DTH...................  ................  ................  ................  ................
----------------------------------------------------------------------------------------------------------------

    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.

Visual Monitoring

     Monitoring must be conducted by qualified, NMFS-approved 
PSOs, in accordance with the following: PSOs must be independent (i.e., 
not construction personnel) and have no other assigned tasks during 
monitoring periods. At least one PSO must have

[[Page 56919]]

prior experience performing the duties of a PSO during construction 
activity pursuant to a NMFS-issued incidental take authorization. Other 
PSOs may substitute other relevant experience, education (degree in 
biological science or related field), or training. PSOs must be 
approved by NMFS prior to beginning any activity subject to this IHA.
     PSOs must record all observations of marine mammals as 
described in the Section 5 of the IHA and the Marine Mammal Monitoring 
Plan, regardless of distance from the pile being driven. PSOs shall 
document any behavioral reactions in concert with distance from piles 
being driven or removed;
    PSOs must have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates, times, and reason for implementation 
of mitigation (or why mitigation was not implemented when required); 
and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary;
     CTJV must establish the following monitoring locations. 
For all pile driving and DTH activities, a minimum of one PSO must be 
assigned to the active pile driving or DTH location to monitor the 
shutdown zones and as much of the Level A and Level B harassment zones 
as possible. For activities in Table 7 above with Level B harassment 
zones larger than 6000 meters, an additional PSO must be stationed at 
Fort Story to monitor as much of the Level B harassment zone as 
possible.

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving and removal 
activities, or 60 days prior to a requested date of issuance of any 
future IHAs for projects at the same location, whichever comes first. 
The report will include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the report must include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including the number and type of piles driven or 
removed and by what method (i.e., impact or cutting) and the total 
equipment duration for cutting for each pile or total number of strikes 
for each pile (impact driving);
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: Name of PSO who sighted the animal(s) and PSO location and 
activity at time of sighting; Time of sighting; Identification of the 
animal(s) (e.g., genus/species, lowest possible taxonomic level, or 
unidentified), PSO confidence in identification, and the composition of 
the group if there is a mix of species; Distance and bearing of each 
marine mammal observed relative to the pile being driven for each 
sighting (if pile driving was occurring at time of sighting); Estimated 
number of animals (min/max/best estimate); Estimated number of animals 
by cohort (adults, juveniles, neonates, group composition, etc.); 
Animal's closest point of approach and estimated time spent within the 
harassment zone; Description of any marine mammal behavioral 
observations (e.g., observed behaviors such as feeding or traveling), 
including an assessment of behavioral responses thought to have 
resulted from the activity (e.g., no response or changes in behavioral 
state such as ceasing feeding, changing direction, flushing, or 
breaching);
     Number of marine mammals detected within the harassment 
zones, by species; and
     Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensued, and resulting changes in behavior of the 
animal(s), if any.
    If no comments are received from NMFS within 30 days, the draft 
final report will constitute the final report. If comments are 
received, a final report addressing NMFS comments must be submitted 
within 30 days after receipt of comments.

Reporting Injured or Dead Marine Mammals

    In the event that personnel involved in the construction activities 
discover an injured or dead marine mammal, the IHA-holder must 
immediately cease the specified activities and report the incident to 
the Office of Protected Resources (OPR) 
([email protected]), NMFS and to Greater Atlantic 
Regional Stranding Coordinator as soon as feasible. If the death or 
injury was clearly caused by the specified activity, CTJV must 
immediately cease the specified activities until NMFS is able to review 
the circumstances of the incident and determine what, if any, 
additional measures are appropriate to ensure compliance with the terms 
of the IHA. The IHA-holder must not resume their activities until 
notified by NMFS. The report must include the following information:
     Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
     Species identification (if known) or description of the 
animal(s) involved;
     Condition of the animal(s) (including carcass condition if 
the animal is dead);
     Observed behaviors of the animal(s), if alive;
     If available, photographs or video footage of the 
animal(s); and
     General circumstances under which the animal was 
discovered.

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

[[Page 56920]]

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).
    Pile driving and removal and DTH activities have the potential to 
disturb or displace marine mammals. Specifically, the project 
activities may result in take, in the form of Level A and Level B 
harassment from underwater sounds generated from pile driving and 
removal and DTH. Potential takes could occur if individuals are present 
in the ensonified zone when these activities are underway.
    The takes from Level A and Level B harassment would be due to 
potential behavioral disturbance, TTS, and PTS. No serious injury or 
mortality is anticipated given the nature of the activity and measures 
designed to minimize the possibility of injury to marine mammals. The 
potential for harassment is minimized through the construction method 
and the implementation of the planned mitigation measures (see Proposed 
Mitigation section).
    The Level A harassment zones identified in Table 7 are based upon 
an animal exposed to impact pile driving multiple piles per day. 
Considering the short duration to impact drive or DTH each pile and 
breaks between pile installations (to reset equipment and move pile 
into place), this means an animal would have to remain within the area 
estimated to be ensonified above the Level A harassment threshold for 
multiple hours. This is highly unlikely given marine mammal movement 
throughout the area. If an animal was exposed to accumulated sound 
energy, the resulting PTS would likely be small (e.g., PTS onset) at 
lower frequencies where pile driving energy is concentrated, and 
unlikely to result in impacts to individual fitness, reproduction, or 
survival.
    The nature of the pile driving project precludes the likelihood of 
serious injury or mortality. For all species and stocks, take would 
occur within a limited, confined area (adjacent to the CBBT) of the 
stock's range. Level A and Level B harassment will be reduced to the 
level of least practicable adverse impact through use of mitigation 
measures described herein. Further the amount of take proposed to be 
authorized is extremely small when compared to stock abundance.
    Behavioral responses of marine mammals to pile driving at the 
project site, if any, are expected to be mild and temporary. Marine 
mammals within the Level B harassment zone may not show any visual cues 
they are disturbed by activities (as noted during modification to the 
Kodiak Ferry Dock) or could become alert, avoid the area, leave the 
area, or display other mild responses that are not observable such as 
changes in vocalization patterns. Given the short duration of noise-
generating activities per day, any harassment would be temporary. There 
are no other areas or times of known biological importance for any of 
the affected species.
    We acknowledge the existence and concern about the ongoing humpback 
whale UME. We have no evidence that this project is likely to result in 
vessel strikes (a major correlate of the UME) and marine construction 
projects in general involve the use of slow-moving vessels, such as 
tugs towing or pushing barges, or smaller work boats maneuvering in the 
vicinity of the construction project. These vessel types are not 
typically associated with vessel strikes resulting in injury or 
mortality. More generally, the UME does not yet provide cause for 
concern regarding population-level impacts for humpback whales. Despite 
the UME, the West Indies breeding population or DPS, remains healthy.
    In addition, it is unlikely that minor noise effects in a small, 
localized area of habitat would have any effect on the stocks' ability 
to recover. In combination, we believe that these factors, as well as 
the available body of evidence from other similar activities, 
demonstrate that the potential effects of the specified activities will 
have only minor, short-term effects on individuals. The specified 
activities are not expected to impact rates of recruitment or survival 
and will therefore not result in population-level impacts.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect the species or stock 
through effects on annual rates of recruitment or survival:
     No mortality is anticipated or authorized;
     Authorized Level A harassment would be very small amounts 
and of low degree;
     No important habitat areas have been identified within the 
project area;
     For all species, Chesapeake Bay is a very small and 
peripheral part of their range;
     CTJV would implement mitigation measures such as bubble 
curtains, soft-starts, and shut downs; and
     Monitoring reports from similar work in Chesapeake Bay 
have documented little to no effect on individuals of the same species 
impacted by the specified activities.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Small Numbers

    As noted above, only small numbers of incidental take may be 
authorized under section 101(a)(5)(D) of the MMPA for specified 
activities other than military readiness activities. The MMPA does not 
define small numbers and so, in practice, where estimated numbers are 
available, NMFS compares the number of individuals taken to the most 
appropriate estimation of abundance of the relevant species or stock in 
our determination of whether an authorization is limited to small 
numbers of marine mammals. When the predicted number of individuals to 
be taken is fewer than one third of the species or stock abundance, the 
take is considered to be of small numbers. Additionally, other 
qualitative factors may be considered in the analysis, such as the 
temporal or spatial scale of the activities.
    The amount of take NMFS proposes to authorize is below one third of 
the estimated stock abundance for humpback whale, harbor porpoise, gray 
seal, harbor seal (in fact, take of individuals is less than 10 percent 
of the abundance of the affected stocks, see Table 7). This is likely a 
conservative estimate because they assume all takes are of different 
individual animals which is likely not the case. Some individuals may 
return multiple times in a day, but PSOs would count them as separate 
takes if they cannot be individually identified.
    There are three bottlenose dolphin stocks that could occur in the 
project area. Therefore, the estimated 86,656 dolphin takes by Level B 
harassment would likely be split among the western North Atlantic 
northern migratory

[[Page 56921]]

coastal stock, western North Atlantic southern migratory coastal stock, 
and NNCES stock. Based on the stocks' respective occurrence in the 
area, NMFS estimated that there would be no more than 250 takes from 
the NNCES stock, representing 30.4 percent of that population, with the 
remaining takes split evenly between the northern and southern 
migratory coastal stocks. Based on consideration of various factors 
described below, we have determined the numbers of individuals taken 
would comprise less than one-third of the best available population 
abundance estimate of either coastal migratory stock. Detailed 
descriptions of the stocks' ranges have been provided in Description of 
Marine Mammals in the Area of Specified Activities.
    Both the northern migratory coastal and southern migratory coastal 
stocks have expansive ranges and they are the only dolphin stocks 
thought to make broad-scale, seasonal migrations in coastal waters of 
the western North Atlantic. Given the large ranges associated with 
these two stocks it is unlikely that large segments of either stock 
would approach the project area and enter into the Chesapeake Bay. The 
majority of both stocks are likely to be found widely dispersed across 
their respective habitat ranges and unlikely to be concentrated in or 
near the Chesapeake Bay.
    Furthermore, the Chesapeake Bay and nearby offshore waters 
represent the boundaries of the ranges of each of the two coastal 
stocks during migration. The northern migratory coastal stock is found 
during warm water months from coastal Virginia, including the 
Chesapeake Bay and Long Island, New York. The stock migrates south in 
late summer and fall. During cold water months dolphins may be found in 
coastal waters from Cape Lookout, North Carolina, to the North 
Carolina/Virginia. During January-March, the southern migratory coastal 
stock appears to move as far south as northern Florida. From April to 
June, the stock moves back north to North Carolina. During the warm 
water months of July-August, the stock is presumed to occupy coastal 
waters north of Cape Lookout, North Carolina, to Assateague, Virginia, 
including the Chesapeake Bay. There is likely some overlap between the 
northern and southern migratory stocks during spring and fall 
migrations, but the extent of overlap is unknown.
    The Bay and waters offshore of the mouth are located on the 
periphery of the migratory ranges of both coastal stocks (although 
during different seasons). Additionally, each of the migratory coastal 
stocks are likely to be located in the vicinity of the Bay for 
relatively short timeframes. Given the limited number of animals from 
each migratory coastal stock likely to be found at the seasonal 
migratory boundaries of their respective ranges, in combination with 
the short time periods (~2 months) animals might remain at these 
boundaries, it is reasonable to assume that takes are likely to occur 
only within some small portion of either of the migratory coastal 
stocks.
    Both migratory coastal stocks likely overlap with the NNCES stock 
at various times during their seasonal migrations. The NNCES stock is 
defined as animals that primarily occupy waters of the Pamlico Sound 
estuarine system (which also includes Core, Roanoke, and Albemarle 
sounds, and the Neuse River) during warm water months (July-August). 
Members of this stock also use coastal waters (<=1 km from shore) of 
North Carolina from Beaufort north to Virginia Beach, Virginia, 
including the lower Chesapeake Bay. Comparison of dolphin photo-
identification data confirmed that limited numbers of individual 
dolphins observed in Roanoke Sound have also been sighted in the 
Chesapeake Bay (Young, 2018). Like the migratory coastal dolphin 
stocks, the NNCES stock covers a large range. The spatial extent of 
most small and resident bottlenose dolphin populations is on the order 
of 500 km\2\, while the NNCES stock occupies over 8,000 km\2\ 
(LeBrecque et al., 2015). Given this large range, it is again unlikely 
that a preponderance of animals from the NNCES stock would depart the 
North Carolina estuarine system and travel to the northern extent of 
the stock's range and enter into the Bay. However, recent evidence 
suggests that there is likely a small resident community of NNCES 
dolphins of indeterminate size that inhabits the Chesapeake Bay year-
round (Eric Patterson, Personal Communication).
    Many of the dolphin observations in the Bay are likely repeated 
sightings of the same individuals. The Potomac-Chesapeake Dolphin 
Project has observed over 1,200 unique animals since observations began 
in 2015. Re-sightings of the same individual can be highly variable. 
Some dolphins are observed once per year, while others are highly 
regular with greater than 10 sightings per year (Mann, Personal 
Communication). Similarly, using available photo-identification data, 
Engelhaupt et al. (2016) determined that specific individuals were 
often observed in close proximity to their original sighting locations 
and were observed multiple times in the same season or same year. 
Ninety-one percent of re-sighted individuals (100 of 110) in the study 
area were recorded less than 30 km from the initial sighting location. 
Multiple sightings of the same individual would considerably reduce the 
number of individual animals that are taken by harassment. Furthermore, 
the existence of a resident dolphin population in the Bay would 
increase the percentage of dolphin takes that are actually re-sightings 
of the same individuals.
    Monitoring reports and data from prior years of the project work 
have recorded less than 10 level B takes of bottlenose dolphins in over 
100 days of monitored pile driving.
    In summary and as described above, the following factors primarily 
support our preliminary determination regarding the incidental take of 
small numbers of a species or stock:
     The take of marine mammal stocks authorized for take 
comprises less than 10 percent of any stock abundance (with the 
exception of bottlenose dolphin stocks);
     Potential bottlenose dolphin takes in the project area are 
likely to be allocated among three distinct stocks;
     Bottlenose dolphin stocks in the project area have 
extensive ranges and it would be unlikely to find a high percentage of 
any one stock concentrated in a relatively small area such as the 
project area or the Bay;
     The Bay represents the migratory boundary for each of the 
specified dolphin stocks and it would be unlikely to find a high 
percentage of any stock concentrated at such boundaries;
     Monitoring from prior years found less than 10 level B 
takes of bottlenose dolphin in over 100 days of monitored pile driving; 
and
     Many of the takes would be repeats of the same animal and 
it is likely that a number of individual animals could be taken 10 or 
more times.
    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

[[Page 56922]]

such species or stocks for taking for subsistence purposes.

Endangered Species Act

    Section 7(a)(2) of the ESA (16 U.S.C. 1531 et seq.) requires that 
each Federal agency insure that any action it authorizes, funds, or 
carries out is not likely to jeopardize the continued existence of any 
endangered or threatened species or result in the destruction or 
adverse modification of designated critical habitat. To ensure ESA 
compliance for the issuance of IHAs, NMFS consults internally whenever 
we propose to authorize take for endangered or threatened species.
    No incidental take of ESA-listed species is proposed for 
authorization or expected to result from this activity. Therefore, NMFS 
has determined that formal consultation under section 7 of the ESA is 
not required for this action.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to the CTJV to conduct the Parallel Thimble Shoal Tunnel 
Project in Virginia Beach, Virginia for 1 year from the date of 
issuance, provided the previously mentioned mitigation, monitoring, and 
reporting requirements are incorporated. A draft of the proposed IHA 
can be found at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the proposed 
Parallel Thimble Shoal Tunnel project. We also request at this time 
comment on the potential renewal of this proposed IHA as described in 
the paragraph below. Please include with your comments any supporting 
data or literature citations to help inform decisions on the request 
for this IHA or a subsequent Renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time 1 year Renewal 
IHA following notification to the public providing an additional 15 
days for public comments when (1) up to another year of identical, or 
nearly identical, activities as described in the Description of 
Proposed Activity section of this notification is planned or (2) the 
activities as described in the Description of Proposed Activity section 
of this notification 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 notification, 
provided all of the following conditions are met:
     A request for renewal is received no later than 60 days 
prior to the needed Renewal IHA effective date (recognizing that 
Renewal IHA expiration date cannot extend beyond one year from 
expiration of the initial IHA);
     The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested Renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take); 
and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized; and
     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: October 6, 2021.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2021-22191 Filed 10-12-21; 8:45 am]
BILLING CODE 3510-22-P