Notice2026-21419
Takes of Marine Mammals Incidental To Specified Activities; Taking Marine Mammals Incidental to the U.S. Navy's TRF Wharf Interface Repairs Project at U.S. Naval Submarine Base Kings Bay, Georgia
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
October 20, 2026
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from the U.S. Navy (Navy) for authorization to take marine mammals incidental to construction activities associated with Trident Refit Facility (TRF) wharf interface repairs project at Naval Submarine Base (NSB) Kings Bay, Georgia. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue an incidental harassment authorization (IHA) to take marine mammals incidental to the specified activities. NMFS is also requesting comments on a possible one-time, 1-year renewal that could be issued under certain circumstances and if all requirements are met, as described in Request for Public Comments at the end of this notice. NMFS will consider public comments prior to making any final decision on the issuance of the requested MMPA authorization.
Full Text
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<title>Federal Register, Volume 91 Issue 201 (Tuesday, October 20, 2026)</title>
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[Federal Register Volume 91, Number 201 (Tuesday, October 20, 2026)]
[Notices]
[Pages 66295-66316]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-21419]
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DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XG041]
Takes of Marine Mammals Incidental To Specified Activities;
Taking Marine Mammals Incidental to the U.S. Navy's TRF Wharf Interface
Repairs Project at U.S. Naval Submarine Base Kings Bay, Georgia
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 U.S. Navy (Navy) for
authorization to take marine mammals incidental to construction
activities associated with Trident Refit Facility (TRF) wharf interface
repairs project at Naval Submarine Base (NSB) Kings Bay, Georgia.
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting
comments on its proposal
[[Page 66296]]
to issue an incidental harassment authorization (IHA) to take marine
mammals incidental to the specified activities. NMFS is also requesting
comments on a possible one-time, 1-year renewal that could be issued
under certain circumstances and if all requirements are met, as
described in Request for Public Comments at the end of this notice.
NMFS will consider public comments prior to making any final decision
on the issuance of the requested MMPA authorization.
DATES: Comments and information must be received no later than November
19, 2026.
ADDRESSES: Comments should be addressed to Permits and Conservation
Division, Office of Protected Resources, NMFS, and should be submitted
via email to <a href="/cdn-cgi/l/email-protection#074e53572943626a6675627473476968666629606871"><span class="__cf_email__" data-cfemail="91d8c5c1bfd5f4fcf0e3f4e2e5d1fffef0f0bff6fee7">[email protected]</span></a>. 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: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. In case of problems
accessing these documents, please call the contact listed below.
Instructions: NMFS is not responsible for comments sent by any
other method, to any other address or individual, or received after the
end of the comment period. Comments, including all attachments, must
not exceed a 25-megabyte file size. All comments received are a part of
the public record and will generally be posted online at <a href="https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act">https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act</a> 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: Austin Demarest, Office of Protected
Resources, NMFS, (301) 427-8401.
SUPPLEMENTARY INFORMATION:
Background
The MMPA prohibits the ``take'' of marine mammals, with certain
exceptions. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et
seq.) directs 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 proposed or, if the taking is limited to harassment, a notice of a
proposed IHA is 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). If such findings are made, NMFS must prescribe the
permissible methods of taking; 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 as ``mitigation''); and requirements pertaining to the monitoring
and reporting of the takings. The definitions of all applicable MMPA
statutory terms used above are included in the relevant sections below
(see also 16 U.S.C. 1362; 50 CFR 216.3, 216.103).
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 NAO 216-6A, which do not
individually or cumulatively have the potential for significant impacts
on the quality of the human environment and for which we have not
identified any extraordinary circumstances that would preclude this
categorical exclusion. Accordingly, NMFS has preliminarily determined
that the issuance of the proposed IHA qualifies to be categorically
excluded from further NEPA review.
Summary of Request
On March 12, 2026, NMFS received an email request from the Navy for
an IHA to take marine mammals incidental to impact pile driving and
vibratory pile removal on the East River at the naval submarine base
NSB Kings Bay, Georgia. Following NMFS' review of the application, the
Navy submitted two revised versions on July 9, 2026, and on August 4,
2026. The application was deemed adequate and complete on August 17,
2026. The Navy's request is for take of Tamanend's bottlenose dolphins
(Tursiops erebennus) from the Southern Georgia Estuarine System (SGES)
stock by Level B harassment only. Neither the Navy nor NMFS expect
serious injury or mortality to result from this activity and,
therefore, an IHA is appropriate.
NMFS previously issued 5-year regulations and an associated Letter
of Authorization to the Navy for similar work at NSB Kings Bay (82 FR
26360, June 7, 2017; 82 FR 39568, August 21, 2017). The letter of
authorization (LOA) expired on July 11, 2022. Information regarding the
Navy's activities under that previous LOA may be found on NMFS web page
at: <a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-submarine-base-kings-bay-waterfront-construction-kings">https://www.fisheries.noaa.gov/action/incidental-take-authorization-us-navy-submarine-base-kings-bay-waterfront-construction-kings</a>.
Description of Proposed Activity
Overview
NSB Kings Bay on the East River in Georgia is the sole homeport on
the east coast of the United States that was built to support the
repair and maintenance of Trident Ship Submersible Ballistic and
Nuclear-Powered Guided Missile Submarines. The waterfront
infrastructure at the TRF wharf interface has severely degraded; the
steel piles are corroded, and the concrete structures are spalling and
delaminating. To maintain crucial submarine servicing capacity, the
Navy proposes the TRF wharf interface repairs project to remove
existing structures and replace them with new structures at the east
and west wharfs. The east wharf consists of two concrete dolphin piers
supported by steel piles, walkway ramps, mooring hardware, a fender
system, a submerged caisson mooring pad, and the caisson gate mooring
dock. The west wharf consists of three steel pile coffer cells, a
concrete caisson, and hotel barge mooring system. In-water construction
is planned to occur over a 1-year period, spanning 54 non-consecutive
days.
Activities that have the potential to cause incidental take of
marine mammals include vibratory pile removal of existing steel H-piles
and impact driving new, permanent concrete piles. These activities may
result in the incidental take of one stock of marine mammals,
specifically the SGES stock of Tamanend's bottlenose dolphins, by Level
B harassment only. No Level A harassment, serious injury, or mortality
is expected or proposed for authorization.
[[Page 66297]]
Dates and Duration
The proposed IHA would be valid for the statutory maximum of 1 year
from the date of effectiveness. It will become effective upon written
notification from the applicant to NMFS but not beginning later than 1
year from the date of issuance or extending beyond 2 years from the
date of issuance. The specified activities are expected to occur over
54 non-consecutive days between January 2027 to December 2027, during
daylight hours from 1 hour after sunrise to 1 hour before sunset.
However, project delays may occur due to a number of factors, including
project funding, permitting requirements, availability of equipment
and/or materials, weather-related delays, equipment maintenance and/or
repair, transit to and from ports to survey locations, and other
contingencies.
Specific Geographic Region
The Navy would replace infrastructure at NSB Kings Bay in the East
River, situated in the eastern corner of Georgia, approximately 13
kilometers (km) north of the Florida-Georgia border, and approximately
14.8 km upstream from the Atlantic Ocean (figure 1). NSB Kings Bay
encompasses a 16,000-acre area that provides berthing facilities and
support services for naval submarines and other assets. The area is
restricted to general public access and includes the East River and
adjacent waters of the Cumberland Sound between Marianna Creek to the
north and Mill creek to the south. However, the ensonified areas for
the specified activities would not extend beyond the East River.
The environment of NSB Kings Bay is estuarine, receives saltwater
inputs from tidal exchange with the ocean, and freshwater inputs from
rivers, tributaries, and stormwater outfalls. The area has a large
tidal range and contains strong currents which results in tidal mixing
with water refreshed daily. See section 2 of the Navy's application for
more detailed information.
BILLING CODE 3510-22-P
[GRAPHIC] [TIFF OMITTED] TN20OC26.039
BILLING CODE 3510-22-C
Detailed Description of the Specified Activity
Construction activities at NSB Kings Bay for the TRF wharf repairs
project would occur at the east wharf interface, the east wharf
interface dolphin piers, and the west wharf interface. Construction
would involve the following repairs:
<bullet> Corrosion repair of concrete structures;
<bullet> Repair of deteriorated concrete piles;
<bullet> Creation of concrete fascia to protect existing coffer
cells from further concrete corrosion;
<bullet> Demolition of the existing fender system and installation
of a new fender system at the mooring dolphin piers, including the
cleaning and installation of hardware, as needed;
<bullet> Removal of corroded steel H-piles along the east and west
wharf; and
<bullet> Installation of new concrete piles for a new fender system
along the east and west wharf.
For in-water construction, a total of 102 degraded 14-inch steel H-
piles will be removed with a vibratory hammer, and then 112 20-inch
square concrete replacement piles will be installed with an impact
hammer (tables 1 and 2). Both pile removal and pile installation
activities may occur on the same day but they will not occur
simultaneously. If concrete piles are unable to reach
[[Page 66298]]
embedment depth with an impact hammer, these piles will be removed with
direct pull methods, and then an auger will be used to drill through
the limestone layers. Finally, these piles will be reinstalled with an
impact hammer to reach embedment depth. Augering and other construction
activities listed above, except vibratory pile removal and impact pile
driving, are not expected to produce underwater sound at high enough
levels or at a long enough duration to result in the incidental take of
marine mammals. Therefore, these activities are not discussed further.
For the east wharf interface (excluding the dolphin pier), 33 14-
inch steel H-piles from the existing fender mooring system will be
removed with a vibratory hammer over 6 days. Following removal, 35 20-
inch square concrete piles for a new fender mooring system will be
installed with an impact hammer over 11 days. Total in-water
construction for the east wharf interface will occur over 17 non-
consecutive days.
For the east wharf interface dolphin pier, six 14-inch steel H-
Piles will be removed with a vibratory hammer over 2 days, and six 20-
inch square concrete piles would be installed with an impact hammer
over 2 days. To maintain the dolphin piers structural integrity during
construction, activities will not be conducted in an entirely
sequential manner. Instead, the Navy will remove four initial steel H-
piles, install four replacement concrete piles, remove the last two
steel H-piles, and install the last two concrete piles. Total in-water
construction for the east wharf interface dolphin pier will occur over
a total of 4 non-consecutive days.
For the west wharf interface, 63 14-inch steel H-piles will be
removed with a vibratory hammer for over 10 days, and 71 20-inch square
concrete piles will be installed with an impact hammer for the new
fender mooring system over 23 days. Total in-water construction for the
west wharf interface will occur over a total of 33 non-consecutive
days.
Incidental take of marine mammals by Level B behavioral harassment
could occur from vibratory pile removal and impact pile installation.
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting sections).
Table 1--TRF Wharf Interface Repairs Project Vibratory Pile Extraction Summary
----------------------------------------------------------------------------------------------------------------
Pile size and Time/pile Number of
Project component type Piles/day (minutes) piles Number of days
----------------------------------------------------------------------------------------------------------------
East Wharf.................... 14-inch, Steel H 8 10 33 6
East Wharf Dolphin Pier....... ................ 4 10 6 2
West Wharf.................... ................ 8 10 63 10
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Totals.................... ................ .............. .............. 102 18
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Table 2--TRF Interface Wharf Repairs Project Impact Pile Installation Summary
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Pile size and Number of
Project component type Piles/day Strikes/pile piles Number of days
----------------------------------------------------------------------------------------------------------------
East Wharf.................... 20-inch, Square 4 500 35 11
Concrete.
East Wharf Dolphin Pier....... ................ .............. .............. 6 2
West Wharf.................... ................ .............. .............. 71 23
---------------------------------------------------------------
Totals.................... ................ .............. .............. 112 36
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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. NMFS
fully considered all of this information, and we refer the reader to
these descriptions, instead of reprinting the information. Additional
information regarding population trends and threats may be found in
NMFS' Stock Assessment Reports (SARs) (<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>) and
more general information about these species (e.g., physical and
behavioral descriptions) may be found on NMFS' website (<a href="https://www.fisheries.noaa.gov/find-species">https://www.fisheries.noaa.gov/find-species</a>).
Table 3 lists the species and stock for which take is likely and
proposed to be authorized for this activity 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. PBR is defined by the MMPA as the maximum
number of animals, not including natural mortalities, that may be
removed from a marine mammal stock while allowing that stock to reach
or maintain its optimum sustainable population (as described in NMFS'
SARs). While no serious injury or mortality is anticipated or proposed
to be authorized here, PBR and annual mortality and serious injury (M/
SI) from anthropogenic sources are included here as gross indicators of
the status of the species or stocks and other threats.
Marine mammal abundance estimates presented in this document
represent the total number of individuals that make up a given stock or
the total number estimated within a particular study or survey area.
NMFS' stock abundance estimates for most species represent the total
estimate of individuals within the geographic area, if known, that
comprises that stock. For some species, this geographic area may extend
beyond U.S. waters. All managed stocks in this region are assessed in
NMFS' U.S. Atlantic Ocean and Gulf of America SARs. All values
presented in table 3 are the most recent available at the time of
publication (including from
[[Page 66299]]
the final 2024 SARs) and are available online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments</a>.
Table 3--Species, Stocks, and the Status of Marine Mammals \1\ With Estimated Take From the Specified Activities
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Stock abundance (CV,
ESA/MMPA status; Nmin, most recent Annual M/SI
Common name Scientific name Stock strategic (Y/N) abundance survey) PBR \4\
\2\ \3\
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Order Odontoceti (toothed whales, dolphins, and porpoises)
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Family Delphinidae:
Tamanend's Bottlenose Dolphin. Tursiops erebennus... Southern Georgia -, -, N UNK (UNK, UNK, 2008- UND 0.1
Estuarine. 2009) \5\.
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\1\ Information on the classification of marine mammal species can be found on the web page for the Society for Marine Mammalogy's Committee on Taxonomy
(<a href="https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/">https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/</a>).
\2\ 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.
\3\ NMFS marine mammal stock assessment reports online at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports</a>. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
commercial fisheries, vessel strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range.
\5\ The total number of common bottlenose dolphins residing within this stock is unknown because previous estimates are greater than 8 years old.
Present data are insufficient to calculate a minimum population estimate for this stock. In addition, the previous abundance estimate covered
approximately half of the entire range of the SGES stock and, therefore, is negatively biased.
As indicated above, only Tamanend's bottlenose dolphins from the
SGES stock overlap temporally and spatially with the specified activity
to the extent that take is likely (table 3). All species that could
potentially occur in the proposed project areas are included table 4 of
the IHA application. While table 4 of the Navy's application lists
Tamanend's bottlenose dolphins from the Northern Georgia/Southern South
Carolina Estuarine System (NGSCES), Central Georgia Estuarine System
(CGES), and Jacksonville Estuarine System (JES) stocks as 'rare' in the
project area, NMFS disagrees with this characterization because their
spatial distribution does not overlap with the action area. Because
their spatial and temporal ranges do not overlap with the specified
activity, they are not expected to occur, take is not expected, and
these stocks are not discussed further beyond the explanation provided
here.
Specifically, the NGSCES stock's distribution ranges from the North
Edisto River to the northern extent of Ossabaw Sound (approximately 64
nautical miles (nmi) north); the CGES stock's distribution ranges from
Ossabaw Sound to the Altamaha Sound (approximately 38 nmi north); and
the JES stock's distribution ranges from the Florida/Georgia border at
Cumberland Sound to Jacksonville Beach, Florida (approximately 5.5 nmi
south). Because the spatial distributions of these three stocks do not
overlap with the project area, and harassment zones are fully
encompassed within the East River, take of these stocks is not expected
or proposed to be authorized.
In addition, the West Indian manatee may be found in the East River
in Georgia; however, West Indian manatees are managed by the U.S. Fish
and Wildlife Service and are not considered further in this document.
Bottlenose dolphins frequently occur in estuarine and nearshore
waters of southern Georgia, including the East River and the Cumberland
Sound. Atlantic coastal and estuarine bottlenose dolphins were
recategorized as Tamanend's bottlenose dolphins (Tursiops erebennus) by
Costa et al. (2022). All bottlenose dolphins occurring within the
project area are expected to belong to the SGES stock. The SGES stock
geographic distribution is bounded by the Altamaha Sound to the north,
the Florida/Georgia border in the Cumberland Sound to the south, and
coastal waters within 1 km of shore (NMFS, 2023a). Because this stock
has small geographic range, this area of southern Georgia is designated
as a Small and Resident Population Biologically Important Area (BIA),
encompassing approximately 410 km\2\.
Speakman et al. (2023) conducted vessel-based dolphin photo-
identification surveys from April 2010 through May 2021 in estuarine
and nearshore coastal waters (<5 km) from the Altamaha Sound to the
Florida/Georgia border, encompassing the entirety of the SGES stock
range. Their research confirmed high year-round site fidelity and
localized residency within this estuarine system, supporting stock
boundaries and presence. Across the 163 surveys, 768 distinctively
marked photo-identified individual dolphins were documented (with a
discovery curve that did not asymptote, indicating a larger
population). Additionally, Speakman et al. (2023) performed a cluster
analysis on individual dolphins (n=98) that were sighted at least 10
times, which identified 5 distinct social clusters. Across all five
social clusters, the mean group size was 6.7 animals. While two social
clusters have utilization distributions in the general surrounding
region, fine-scale spatial mapping indicates that the core range of
only one social cluster directly overlaps the project area (located
within 2 nmi). The second social cluster's range lies farther away,
outside the primary area of project effects. Consequently, project
activities are expected to impact individuals from only this single
overlapping social cluster.
The SGES stock dolphins utilize river estuaries, river channels,
and tidal creeks between the Altamaha Sound and Cumberland Sound
primarily for foraging, socializing, and transiting (Balmer et al.,
2013; NMFS, 2023a).
[[Page 66300]]
Local observations by subject matter experts (SMEs) at NSB Kings Bay
confirm regular dolphin presence, with SMEs routinely observing two to
three groups of dolphins daily in the project vicinity, where typical
group sizes range from three to four individuals. Based on these local
SME observations and known estuarine habitat use, individuals from this
specific social cluster are expected to occur in the project area daily
during the specified activities.
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. Not all marine mammal species have equal
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al.
(2007; 2019) recommended that marine mammals be divided into hearing
groups based on directly measured (behavioral or auditory evoked
potential techniques) or estimated hearing ranges (behavioral response
data, anatomical modeling, etc.). Generalized hearing ranges were
chosen based on the approximately 65-decibel (dB) threshold from
composite audiograms, previous analyses in NMFS (2018), and/or data
from Southall et al. (2007; 2019). We note that the names of two
hearing groups and the generalized hearing ranges of all marine mammal
hearing groups have been recently updated (NMFS, 2024) as reflected
below in table 4.
Table 4--Marine Mammal Hearing Groups
[NMFS, 2024]
------------------------------------------------------------------------
Hearing group Generalized hearing range *
------------------------------------------------------------------------
Low-frequency cetaceans (baleen whales).... 7 Hz to 36 kHz.
High-frequency cetaceans (dolphins, toothed 150 Hz to 160 kHz.
whales, beaked whales, bottlenose whales).
Very High-frequency cetaceans (true 200 Hz to 165 kHz.
porpoises, Kogia, river dolphins,
Cephalorhynchid, Lagenorhynchus cruciger &
L. australis).
Phocid pinnipeds (underwater) (true seals). 40 Hz to 90 kHz.
Otariid pinnipeds (underwater) (sea lions 60 Hz to 68 kHz.
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 may not be as broad. Generalized hearing range
chosen based on approximately 65 dB threshold from composite
audiogram, previous analysis in NMFS (2018), and/or data from Southall
et al. (2007; 2019). Additionally, animals are able to detect very
loud sounds above and below that ``generalized'' hearing range.
For more detail concerning these groups and associated frequency
ranges, please see NMFS (2024) for a review of available information.
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section components of the specified activity may impact marine
mammals and their habitat. The Estimated Take of Marine Mammals section
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 of Marine Mammals 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 whether those impacts are reasonably expected to, or reasonably
likely to, adversely affect the species or stock through effects on
annual rates of recruitment or survival.
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 (American National Standards Institute
(ANSI), 1995). The sound level of an area is defined by the total
acoustic 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 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 activities may be a negligible addition to the local
environment or could form a distinctive signal that may affect marine
mammals.
In-water construction associated with the proposed project would
include vibratory pile removal and impact pile driving. The sounds
produced by these activities fall into one of two general sound types:
impulsive and non-impulsive (defined below). The distinction between
these two sound types is important because they have differing
potential to cause physical effects, particularly with regard to
hearing (e.g., Ward, 1997, in Southall et al., 2007). Please see
Southall et al. (2007) for an in-depth discussion of these concepts.
Impulsive sound sources (e.g., explosions, gunshots, sonic booms,
impact pile driving) are brief (typically considered to be less than 1
second), broadband, atonal transients (ANSI, 1986; National Institute
for Occupational Safety and Health (NIOSH), 1998; International
Organization for Standardization (ISO) 2017; ANSI, 2005; NMFS, 2018)
and occur either as isolated events or repeated in some succession.
Impulsive sounds are all characterized by a relatively rapid rise from
ambient pressure to a maximal pressure value
[[Page 66301]]
followed by a rapid decay period that may include a period of
diminishing, oscillating maximal and minimal pressures, and generally
have an increased capacity to induce physical injury as compared with
sounds that lack these features.
Non-impulsive sounds (e.g., aircraft, machinery operations such as
drilling or dredging, vibratory pile driving, 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 rapid 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).
The Navy's TRF wharf interface repairs project would include the
use of an impact hammer for pile installation and a vibratory hammer
for pile removal. Impact hammers operate by repeatedly dropping 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 are used to remove piles by using
vibration to break the sediment friction, which then allows a crane to
vertically pull the piles out. Sounds produced by vibratory hammers are
non-impulsive; compared to sounds produced by impact hammers, they have
a slower rise time, reducing the probability and severity of injury,
and the sound energy is distributed over a greater amount of time
(Nedwell and Edwards, 2002; Carlson et al., 2005).
The likely or possible impacts of the Navy's proposed activities on
the mammals could involve both non-acoustic and acoustic stressors.
Potential non-acoustic stressors could result from the physical
presence of the equipment and personnel; however, any impacts to marine
mammals are expected to primarily be acoustic in nature.
Potential Effects of Underwater Sound on Marine Mammals
The introduction of anthropogenic noise into aquatic environment
from pile driving and pile removal is the means by which marine mammals
may be harassed from the Navy's specified activities. Anthropogenic
sounds span a broad range of frequencies and sound levels and can have
a range of highly variable impacts on marine life from none or minor to
potentially severe responses depending on received levels, duration of
exposure, behavioral context, and various other factors. Broadly,
underwater sound from active acoustic sources, such as those in the
project, can potentially result in one or more of the following:
temporary or permanent hearing impairment, non-auditory physical or
physiological effects, behavioral disturbance, stress, and masking
(Richardson et al., 1995; Gordon et al., 2003; Nowacek et al., 2007;
Southall et al., 2007; G[ouml]tz et al., 2009).
We describe the more severe effects of certain non-auditory
physical or physiological effects only briefly as we do not expect that
use of impact and vibratory pile driving hammers are reasonably likely
to result in such effects (see below for further discussion). Potential
effects from impulsive sound sources can range in severity from effects
such as behavioral disturbance or tactile perception to physical
discomfort, slight injury of the internal organs and the auditory
system, or mortality (Yelverton et al., 1973). Non-auditory
physiological effects or injuries that theoretically might occur in
marine mammals exposed to high level underwater sound or as a secondary
effect of extreme behavioral reactions (e.g., change in dive profile as
a result of an avoidance reaction) caused by exposure to sound include
neurological effects, bubble formation, resonance effects, and other
types of organ or tissue damage (Cox et al., 2006; Southall et al.,
2007; Zimmer and Tyack, 2007; Tal et al., 2015). The specified
activities considered here do not involve the use of devices such as
explosives or mid-frequency tactical sonar that are associated with
these types of effects.
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; 2019). Exposure to
anthropogenic noise has the potential to result in auditory threshold
shifts (TS) and behavioral reactions (e.g., avoidance, temporary
cessation of foraging and vocalizing, changes in dive behavior). It 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 degree of effect of an acoustic exposure on marine mammals is
dependent on several factors, including, but not limited to, sound type
(e.g., impulsive vs. non-impulsive), signal characteristics, the
species, age and sex class (e.g., adult male vs. mom with calf),
duration of exposure, the distance between the noise source and the
animal, received levels, behavioral state at time of exposure, and
previous history with exposure (Wartzok et al., 2004; Southall et al.,
2007). In general, sudden, high-intensity sounds can cause hearing loss
as can longer exposures to lower-intensity sounds. Moreover, any
temporary or permanent loss of hearing, if it occurs at all, will occur
almost exclusively for noise within an animal's hearing range. We
describe below the specific manifestations of acoustic effects that may
occur based on the activities proposed by the Navy.
Richardson et al. (1995) described zones of increasing intensity of
effect that might be expected to occur in relation to distance from a
source and assuming that the signal is within an animal's hearing
range. First (at the greatest distance) is the area within which the
acoustic signal would be audible (potentially perceived) to the animal
but not strong enough to elicit any overt behavioral or physiological
response. The next zone (closer to the receiving animal) corresponds
with the area where the signal is audible to the animal and of
sufficient intensity to elicit behavioral or physiological
responsiveness. The third is a zone within which, for signals of high
intensity, the received level is sufficient to potentially cause
discomfort or tissue damage to auditory or other systems. Overlaying
these zones to a certain extent is the area within which masking (i.e.,
when a sound interferes with or masks the ability of an animal to
detect a signal of interest that is above the absolute hearing
threshold) may occur; the masking zone may be highly variable in size.
Below, we provide additional details regarding potential impacts on
marine mammals and their habitat from noise in general, starting with
hearing impairment, as well as from the specific activities the Navy
plans to conduct, to the degree it is available.
Hearing Threshold Shift--NMFS defines a noise-induced 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, 2024). The amount
of TS is customarily expressed in dB. A TS can be permanent or
temporary. As described in NMFS (2018, 2024) 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
[[Page 66302]]
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
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).
Auditory Injury (AUD INJ)--NMFS (2024) defines AUD INJ as damage to
the inner ear that can result in destruction of tissue, such as the
loss of cochlear neuron synapses or auditory neuropathy (Houser, 2021;
Finneran, 2024). AUD INJ may or may not result in a permanent threshold
shift (PTS). PTS is subsequently defined 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, 2024). PTS does not generally affect more than a
limited frequency range, and an animal that has incurred PTS has some
level of hearing loss at the relevant frequencies; typically, animals
with PTS or other AUD INJ are not functionally deaf (Au and Hastings,
2008; Finneran, 2016). Available data from humans and other terrestrial
mammals indicate that a 40-dB TS approximates AUD INJ onset (Ward et
al., 1958, 1959; Ward, 1960; Kryter et al., 1966; Miller, 1974; Ahroon
et al., 1996; Henderson et al., 2008). AUD INJ levels for marine
mammals are estimates, as with the exception of a single study
unintentionally inducing PTS in a harbor seal (Phoca vitulina) (Kastak
et al., 2008), there are no empirical data measuring AUD INJ in marine
mammals largely due to the fact that, for various ethical reasons,
experiments involving anthropogenic noise exposure at levels inducing
AUD INJ are not typically pursued or authorized (NMFS, 2024).
Temporary Threshold Shift (TTS)--TTS is 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, 2024), and is not considered an AUD INJ. Based
on data from marine mammal TTS measurements (Southall et al., 2007;
2019), a TTS of 6 dB is considered the minimum TS clearly larger than
any day-to-day or session-to-session variation in a subject's normal
hearing ability (Finneran et al., 2000, 2002; Schlundt et al., 2000).
As described in Finneran (2015), marine mammal studies have shown the
amount of TTS increases with the 24-hour cumulative sound exposure
level (SEL<INF>24</INF>) in an accelerating fashion: at low exposures
with lower SEL<INF>24</INF>, the amount of TTS is typically small, and
the growth curves have shallow slopes. At exposures with higher
SEL<INF>24</INF>, the growth curves become steeper and approach linear
relationships with the sound exposure level (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 a 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.
Many studies have examined noise-induced hearing loss in marine
mammals (see Finneran (2015) and Southall et al. (2019) for summaries).
TTS is the mildest form of hearing impairment that can occur during
exposure to sound. While experiencing TTS, the hearing threshold rises,
and a sound must be at a higher level in order to be heard. In
terrestrial and marine mammals, TTS can last from minutes or hours to
days (in cases of strong TTS). In many cases, hearing sensitivity
recovers rapidly after exposure to the sound ends. For cetaceans,
published data on the onset of TTS are limited to captive bottlenose
dolphin (Tursiops truncatus), beluga whale (Delphinapterus leucas),
harbor porpoise (Phocoena phocoena), and Yangtze finless porpoise
(Neophocoena asiaeorientalis) (Southall et al., 2019). For pinnipeds in
water, measurements of TTS are limited to harbor seals, elephant seals
(Mirounga angustirostris), bearded seals (Erignathus barbatus), and
California sea lions (Zalophus californianus) (Kastak et al., 2007;
Kastelein et al., 2019b, 2019c, 2022a, 2022b; Reichmuth et al., 2019;
Sills et al., 2020). TTS was not observed in spotted (Phoca largha) and
ringed (Pusa hispida) seals exposed to single airgun impulse sounds at
levels matching previous predictions of TTS onset (Reichmuth et al.,
2016). These studies examine hearing thresholds measured in marine
mammals before and after exposure to intense or long-duration sound
exposures. The difference between the pre-exposure and post-exposure
thresholds can be used to determine the amount of TS at various post-
exposure times.
The amount and onset of TTS depends on the exposure frequency.
Sounds below the region of best sensitivity for a species or hearing
group are less hazardous than those near the region of best sensitivity
(Finneran and Schlundt, 2013). At low frequencies, onset-TTS exposure
levels are higher compared to those in the region of best sensitivity
(i.e., a low frequency noise would need to be louder to cause TTS onset
when TTS exposure level is higher), as shown for harbor porpoises and
harbor seals (Kastelein et al., 2019a, 2019c). Note that in general,
harbor seals and harbor porpoises have a lower TTS onset than other
measured pinniped or cetacean species (Finneran, 2015). In addition,
TTS can accumulate across multiple exposures, but the resulting TTS
will be less than the TTS from a single, continuous exposure with the
same SEL (Mooney et al., 2009; Finneran et al., 2010; Kastelein et al.,
2014, 2015). This means that TTS predictions based on the total,
SEL<INF>24</INF> will overestimate the amount of TTS from intermittent
exposures, such as sonars and impulsive sources. Nachtigall et al.
(2018) describe measurements of hearing sensitivity of multiple
odontocete species (bottlenose dolphin, harbor porpoise, beluga, and
false killer whale (Pseudorca crassidens)) when a relatively loud sound
was preceded by a warning sound. These captive animals were shown to
reduce hearing sensitivity when warned of an impending intense sound.
Based on these experimental observations of captive animals, the
authors suggest that wild animals may dampen their hearing during
prolonged exposures or if conditioned to anticipate intense sounds.
Another study showed that echolocating animals (including odontocetes)
might have anatomical specializations that might allow for conditioned
hearing reduction and filtering of low-frequency ambient noise,
including increased stiffness and control of middle ear structures and
placement of inner ear structures (Ketten et al., 2021). Data available
on
[[Page 66303]]
noise-induced hearing loss for mysticetes are currently lacking (NMFS,
2024). Additionally, the existing marine mammal TTS data come from a
limited number of individuals within these species.
Relationships between TTS and PTS thresholds have not been studied
in marine mammals, but such relationships are assumed to be similar to
those in humans and other terrestrial mammals. PTS typically occurs at
exposure levels at least several dB above that inducing mild TTS (e.g.,
a 40-dB TS approximates PTS onset (Kryter et al., 1966; Miller, 1974),
while a 6-dB TS approximates TTS onset (Southall et al., 2007; 2019).
Based on data from terrestrial mammals, a precautionary assumption is
that the PTS thresholds for impulsive sounds (such as impact pile
driving pulses as received close to the source) are at least 6 dB
higher than the TTS threshold on a peak-pressure basis and PTS
SEL<INF>24</INF> thresholds are 15 to 20 dB higher than TTS
SEL<INF>24</INF> sound exposure level thresholds (Southall et al.,
2007; 2019). Given the higher level of sound or longer exposure
duration necessary to cause PTS as compared with TTS, it is
considerably less likely that PTS could occur.
Behavioral Effects--Exposure to noise also has the potential to
behaviorally disturb marine mammals to a level that rises to the
definition of harassment under the MMPA. Generally speaking, NMFS
considers a behavioral disturbance that rises to the level of
harassment under the MMPA a non-minor response--in other words, not
every response qualifies as behavioral disturbance, and for responses
that do, those of a higher level, or accrued across a longer duration,
have the potential to affect foraging, reproduction, or survival.
Behavioral disturbance may include a variety of effects, including
subtle changes in behavior (e.g., minor or brief avoidance of an area
or changes in vocalizations), more conspicuous changes in similar
behavioral activities, and more sustained and/or potentially severe
reactions, such as displacement from or abandonment of high-quality
habitat. Behavioral responses may include changing durations of
surfacing and dives, changing direction and/or speed; reducing/
increasing vocal activities; changing/cessation of certain behavioral
activities (such as socializing or feeding); eliciting a visible
startle response or aggressive behavior (such as tail/fin slapping or
jaw clapping); and avoidance of areas where sound sources are located.
In addition, pinnipeds may increase their haul out 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; 2019; 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) and Gomez et al. (2016) for reviews of studies involving marine
mammal behavioral responses to sound.
Habituation can occur when an animal's response to a stimulus wanes
with repeated exposure, usually in the absence of unpleasant associated
events (Wartzok et al., 2003). Animals are most likely to habituate to
sounds that are predictable and unvarying. It is important to note that
habituation is appropriately considered as a ``progressive reduction in
response to stimuli that are perceived as neither aversive nor
beneficial,'' rather than as, more generally, moderation in response to
human disturbance (Bejder et al., 2009). The opposite process is
sensitization, when an unpleasant experience leads to subsequent
responses, often in the form of avoidance, at a lower level of
exposure.
As noted above, behavioral state may affect the type of response.
For example, animals that are resting may show greater behavioral
change in response to disturbing sound levels than animals that are
highly motivated to remain in an area for feeding (Richardson et al.,
1995; Wartzok et al., 2003; National Research Council (NRC), 2005).
Controlled experiments with captive marine mammals have shown
pronounced behavioral reactions, including avoidance of loud sound
sources (Ridgway et al., 1997). Observed responses of wild marine
mammals to loud-pulsed sound sources (e.g., seismic airguns) have been
varied but often consist of avoidance behavior or other behavioral
changes (Richardson et al., 1995; Morton and Symonds, 2002; Nowacek et
al., 2007).
Available studies show wide variation in response to underwater
sounds; therefore, it is difficult to predict specifically how any
given sound in a particular instance might affect marine mammals
perceiving the signal (e.g., Erbe et al., 2019). 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. If a
sound source displaces marine mammals from an important feeding or
breeding area for a prolonged period, impacts on individuals and
populations could be significant (e.g., Lusseau and Bejder, 2007;
Weilgart, 2007; NRC, 2005). However, there are broad categories of
potential response, which we describe in greater detail here, that
include alteration of dive behavior, alteration of foraging behavior,
effects to breathing, interference with or alteration of vocalization,
avoidance, and flight.
Avoidance and Displacement--Changes in dive behavior can vary
widely and may consist of increased or decreased dive times and surface
intervals as well as changes in the rates of ascent and descent during
a dive (e.g., Frankel and Clark, 2000; Costa et al., 2003; Ng and
Leung, 2003; Nowacek et al., 2004; Goldbogen et al., 2013a, 2013b;
Blair et al., 2015). Variations in dive behavior may reflect
interruptions in biologically significant activities (e.g., foraging)
or they may be of little biological significance. The impact of an
alteration to dive behavior resulting from an acoustic exposure depends
on what the animal is doing at the time of the exposure and the type
and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. Acoustic and movement bio-logging tools also have been used
in some cases to infer responses to anthropogenic noise. For example,
Blair et al. (2015) reported significant effects on humpback whale
(Megaptera novaeangliae) foraging behavior in Stellwagen Bank in
response to ship noise including slower descent rates, and fewer side-
rolling events per dive with increasing ship noise. In addition,
Wisniewska et al. (2016) reported that tagged harbor porpoises
demonstrated fewer prey capture attempts when encountering occasional
high-noise
[[Page 66304]]
levels resulting from vessel noise as well as more vigorous fluking,
interrupted foraging, and cessation of echolocation signals observed in
response to some high-noise vessel passes. 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.
Respiration rates vary naturally with different behaviors and
alterations to breathing rate as a function of acoustic exposure can be
expected to co-occur with other behavioral reactions, such as a flight
response or an alteration in diving. However, respiration rates in and
of themselves may be representative of annoyance or an acute stress
response. Various studies have shown that respiration rates may either
be unaffected or could increase, depending on the species and signal
characteristics, again highlighting the importance in understanding
species differences in the tolerance of underwater noise when
determining the potential for impacts resulting from anthropogenic
sound exposure (e.g., Kastelein et al., 2001; 2005; 2006; Gailey et
al., 2007). For example, harbor porpoise respiration rates increased in
response to pile driving sounds at and above a received broadband SPL
of 136 dB (zero-peak SPL: 151 dB (referenced to 1 micropascal (re 1
[mu]Pa); SEL of a single strike (SEL<INF>ss</INF>): 127 dB re 1
[mu]Pa\2\-s) (Kastelein et al., 2013).
Avoidance is the displacement of an individual from an area or
migration path as a result of the presence of a sound or other
stressors and is one of the most obvious manifestations of disturbance
in marine mammals (Richardson et al., 1995). For example, gray whales
(Eschrictius robustus) are known to change direction--deflecting from
customary migratory paths--in order to avoid noise from seismic surveys
(Malme et al., 1984). Harbor porpoises, Atlantic white-sided dolphins
(Lagenorhynchus actusus), and minke whales (Balaenoptera acutorostrata)
have demonstrated avoidance in response to vessels during line transect
surveys (Palka and Hammond, 2001). In addition, beluga whales in the
St. Lawrence Estuary in Canada have been reported to increase levels of
avoidance with increased boat presence by way of increased dive
durations and swim speeds, decreased surfacing intervals, and by
bunching together into groups (Blane and Jaakson, 1994). Avoidance may
be short-term, with animals returning to the area once the noise has
ceased (e.g., Bowles et al., 1994; Goold, 1996; Stone et al., 2000;
Morton and Symonds, 2002; Gailey et al., 2007). Longer-term
displacement is possible, however, which may lead to changes in
abundance or distribution patterns of the affected species in the
affected region if habituation to the presence of the sound does not
occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann et
al., 2006).
A flight response is a dramatic change in normal movement to a
directed and rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
the intensity of the response (e.g., directed movement, rate of
travel). Relatively little information on flight responses of marine
mammals to anthropogenic signals exist, although observations of flight
responses to the presence of predators have occurred (Connor and
Heithaus, 1996; Bowers et al., 2018). The result of a flight response
could range from brief, temporary exertion and displacement from the
area where the signal provokes flight to, in extreme cases, marine
mammal strandings (England et al., 2001). However, it should be noted
that response to a perceived predator does not necessarily invoke
flight (Ford and Reeves, 2008), and whether individuals are solitary or
in groups may influence the response.
Behavioral disturbance can also impact marine mammals in more
subtle ways. Increased vigilance may result in costs related to
diversion of focus and attention (i.e., when a response consists of
increased vigilance, it may come at the cost of decreased attention to
other critical behaviors such as foraging or resting). These effects
have generally not been demonstrated for marine mammals, but studies
involving fishes and terrestrial animals have shown that increased
vigilance may substantially reduce feeding rates (e.g., Beauchamp and
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In
addition, chronic disturbance can cause population declines through
reduction of fitness (e.g., decline in body condition) and subsequent
reduction in reproductive success, survival, or both (e.g., Harrington
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However,
Ridgway et al. (2006) reported that increased vigilance in bottlenose
dolphins exposed to sound over a 5-day period did not cause any sleep
deprivation or stress effects.
Many animals perform vital functions, such as feeding, resting,
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption
of such functions resulting from reactions to stressors such as sound
exposure are more likely to be significant if they last more than one
diel cycle or recur on subsequent days (Southall et al., 2007).
Consequently, a behavioral response lasting less than 1 day and not
recurring on subsequent days is not considered particularly severe
unless it could directly affect reproduction or survival (Southall et
al., 2007). Note that there is a difference between multi-day
substantive (i.e., meaningful) behavioral reactions and multi-day
anthropogenic activities. For example, just because an activity lasts
for multiple days does not necessarily mean that individual animals are
either exposed to activity-related stressors for multiple days or,
further, exposed in a manner resulting in sustained multi-day
substantive behavioral responses.
Physiological 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., Selye,
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
[[Page 66305]]
``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; Ayres et al., 2012; Yang
et al., 2021). 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 (Eubalaena glacialis). In addition,
Lemos et al. (2022) observed a correlation between higher levels of
fecal glucocorticoid metabolite concentrations (indicative of a stress
response) and vessel traffic in gray whales. Yang et al. (2021) studied
behavioral and physiological responses in captive bottlenose dolphins
exposed to playbacks of ``pile-driving-like'' impulsive sounds, finding
significant changes in cortisol and other physiological indicators but
only minor behavioral changes. 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, 2005), however distress is an
unlikely result of this project based on observations of marine mammals
during previous, similar construction projects.
Norman (2011) reviewed environmental and anthropogenic stressors
for Cook Inlet beluga whales. Lyamin et al. (2011) determined that the
heart rate of a beluga whale increases in response to noise, depending
on the frequency and intensity. Acceleration of heart rate in the
beluga whale is the first component of the ``acoustic startle
response.'' Romano et al. (2004) demonstrated that captive beluga
whales exposed to high-level impulsive sounds (i.e., seismic airgun
and/or single pure tones up to 201 dB RMS) resembling sonar pings
showed increased stress hormone levels of norepinephrine, epinephrine,
and dopamine when TTS was reached. Thomas et al. (1990) exposed beluga
whales to playbacks of an oil-drilling platform in operation (``Sedco
708,'' 40 Hz-20 kHz; source level 153 dB). Ambient SPL at ambient
conditions in the pool before playbacks was 106 dB and 134 to 137 dB
RMS during playbacks at the monitoring hydrophone across the pool. All
cell and platelet counts and 21 different blood chemicals, including
epinephrine and norepinephrine, were within normal limits throughout
baseline and playback periods, and stress response hormone levels did
not increase immediately after playbacks. The difference between the
Romano et al. (2004) and Thomas et al. (1990) studies could be the
differences in the type of sound (seismic airgun and/or tone versus oil
drilling), the intensity and duration of the sound, the individual's
response, and the surrounding circumstances of the individual's
environment. The sounds in the Thomas et al. (1990) study would be more
similar to those anticipated by the Navy's activities; therefore, no
more than short-term, low-hormone stress responses, if any, of
Tamanend's bottlenose dolphins are expected as a result of exposure to
noise from the Navy's activities.
Vocalizations and Auditory Masking--Since many marine mammals rely
on sound to find prey, moderate social interactions, and facilitate
mating (Tyack, 2008), noise from anthropogenic sound sources can
interfere with these functions, but only if the noise spectrum overlaps
with the hearing sensitivity of the receiving marine mammal (Southall
et al., 2007; Clark et al., 2009; Hatch et al., 2012). Chronic exposure
to excessive, though not high-intensity, noise could cause masking at
particular frequencies for marine mammals that utilize sound for vital
biological functions (Clark et al., 2009). Acoustic masking is when
other noises such as from human sources interfere with an animal's
ability to detect, recognize, or discriminate between acoustic signals
of interest (e.g., those used for intraspecific communication and
social interactions, prey detection, predator avoidance, navigation)
(Richardson et al., 1995; Erbe et al., 2016). Therefore, under certain
circumstances, marine mammals whose acoustical sensors or environment
are being severely masked could also be impaired from maximizing their
performance fitness in survival and reproduction. 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 (Hotchkin and
Parks, 2013).
Marine mammals vocalize for different purposes and across multiple
modes, such as whistling, echolocation click production, calling, and
singing. Changes in vocalization behavior in response to anthropogenic
noise can occur for any of these modes and may result from a need to
compete with an increase in background noise or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales (Orcinus
orca) have been observed to increase the length of their songs (Miller
et al., 2000; Fristrup et al., 2003) or vocalizations (Foote et al.,
2004), respectively, while North Atlantic right whales have been
observed to shift the frequency content of their calls upward while
reducing the rate of calling in areas of increased anthropogenic noise
(Parks et al., 2007). Fin whales (Balaenoptera physalus) have also been
documented lowering the bandwidth, peak frequency, and center frequency
of their vocalizations under increased levels of background noise from
large vessels (Castellote et al., 2012). Other alterations to
communication signals have also been observed. For example, gray
whales, in response to playback experiments exposing them to vessel
noise, have been observed increasing their vocalization rate and
producing louder signals at times of increased outboard engine noise
(Dahlheim and Castellote, 2016). Alternatively, in some cases, animals
may cease sound production during production of aversive signals
(Bowles et al., 1994, Wisniewska et al., 2016).
Under certain circumstances, marine mammals experiencing
significant masking could also be impaired from maximizing their
performance fitness in survival and reproduction. Therefore, when the
coincident (masking) sound is human made, it may be considered
[[Page 66306]]
harassment when disrupting or altering critical behaviors. It is
important to distinguish TTS and PTS, which persist after the sound
exposure, from masking, which occurs during the sound exposure. Because
masking (without resulting in TS) is not associated with abnormal
physiological function, it is not considered a physiological effect,
but rather a potential behavioral effect (though not necessarily one
that would be associated with harassment).
The frequency range of the potentially masking sound is important
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation
sounds produced by odontocetes but are more likely to affect detection
of mysticete communication calls and other potentially important
natural sounds such as those produced by surf and some prey species.
The masking of communication signals by anthropogenic noise may be
considered as a reduction in the communication space of animals (e.g.,
Clark et al., 2009) and may result in energetic or other costs as
animals change their vocalization behavior (e.g., Miller et al., 2000;
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2010; Holt
et al., 2009). Masking can be reduced in situations where the signal
and noise come from different directions (Richardson et al., 1995),
through amplitude modulation of the signal, or through other
compensatory behaviors, including modifications of the acoustic
properties of the signal or the signaling behavior (Hotchkin and Parks,
2013). Masking can be tested directly in captive species (e.g., Erbe,
2008), but in wild populations it must be either modeled or inferred
from evidence of masking compensation. There are few studies addressing
real-world masking sounds likely to be experienced by marine mammals in
the wild (e.g., Branstetter et al., 2013).
Masking occurs in the frequency band that the animals utilize, is
more likely to occur in the presence of broadband, relatively
continuous noise sources such as vibratory pile driving. Energy
distribution of vibratory pile driving sounds spans a broad frequency
spectrum, and is anticipated to be within the audible range of marine
mammals present in the proposed action area. Since noises generated
from the proposed construction activities are mostly concentrated at
low frequencies (<2 kHz), these activities likely have less effect on
mid-frequency echolocation sounds produced by odontocetes (toothed
whales). However, lower frequency noises are more likely to affect
detection of communication calls and other potentially important
natural sounds such as surf and prey noise. Low-frequency noise may
also affect communication signals when they occur near the frequency
band for noise and thus reduce the communication space of animals
(e.g., Clark et al., 2009) and cause increased stress levels (e.g.,
Holt et al., 2009). Unlike TS, masking, which can occur over large
temporal and spatial scales, can potentially affect the species at
population, community, or even ecosystem levels, in addition to
individual levels. Masking affects both senders and receivers of the
signals, and at higher levels for longer durations, could have long-
term chronic effects on marine mammal species and populations. However,
the noise generated by the Navy's proposed activities will only occur
intermittently, across an estimated 54 days during the authorization
period in a relatively small area focused around the proposed
construction site. Thus, while the Navy's proposed activities may mask
some acoustic signals that are relevant to the daily behavior of marine
mammals, the short-term duration and limited areas affected make it
very unlikely that the fitness of individual marine mammals would be
impacted.
Potential Effects on Marine Mammal Habitat
The Navy's proposed activities would primarily have localized,
temporary impacts on marine mammal habitat, including prey, by
increasing in-water SPLs. Increased noise levels may affect acoustic
habitat and adversely affect marine mammal prey in the vicinity of the
project areas (see discussion below). 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 the proposed construction activities;
however, displacement due to noise is expected to be temporary and is
not expected to result in long-term effects on the individuals or
populations.
The total area likely impacted by the Navy's activities is
relatively small compared to the available habitat in the East River
and the Cumberland Sound. Avoidance by potential prey (e.g., fish and
benthic invertebrates) of the immediate area due to increased noise is
possible. Any behavioral avoidance by fish or marine mammals of the
disturbed area would still leave significantly large areas of fish and
marine mammal foraging habitat in the nearby vicinity.
The proposed project will replace existing NSB Kings Bay
infrastructure and remain within the same footprint. The nearshore
estuarine habitat is in an area of high military vessel and submarine
traffic. According to observations by NSB Kings Bay SMEs, dolphins
generally transit through the project area but do not use the area
within construction site footprint. Temporary, intermittent, and short-
term habitat alteration may result from increased noise levels during
the proposed construction activities. Effects on marine mammals will be
limited to temporary displacement from pile installation and removal
noise, and effects on prey species will be similarly limited in time
and space.
Water quality--Temporary and localized reduction in water quality
will occur as a result of in-water construction activities. Most of
this effect would occur during the installation and removal of piles
when bottom sediments are disturbed. The installation and removal of
piles would disturb bottom sediments and may cause a temporary increase
in suspended sediment in the project area. During pile extraction,
sediment attached to the pile moves vertically through the water column
until gravitational forces cause it to slough off under its own weight.
The small resulting sediment plume is expected to settle out of the
water column within a few hours. Studies of the effects of turbid water
on fish (marine mammal prey) suggest that concentrations of suspended
sediment can reach thousands of milligrams per liter before an acute
toxic reaction is expected (Burton, 1993).
Effects to turbidity and sedimentation are expected to be short-
term, minor, and localized. Since the tides are so strong in the area,
following the completion of sediment-disturbing activities, suspended
sediments in the water column should dissipate and quickly return to
background levels in all construction scenarios. Turbidity within the
water column has the potential to reduce the level of oxygen in the
water and irritate the gills of prey fish species in the proposed
project area. However, turbidity plumes associated with the project
would be temporary and localized, and fish in the proposed project area
would be able to move away from and avoid the areas where plumes may
occur. Therefore, it is expected that the impacts on prey fish species
from turbidity, and therefore on marine mammals, would be minimal and
temporary. In general, the area likely impacted by the proposed
construction activities is relatively small
[[Page 66307]]
compared to the available marine mammal habitat in the East River and
Cumberland Sound.
Potential Effects on Prey--Sound may affect marine mammals through
impacts on the abundance, behavior, or distribution of prey species
(e.g., crustaceans, cephalopods, fishes, zooplankton). Marine mammal
prey varies by species, season, and location and, for some, is not well
documented. Studies regarding the effects of noise on known marine
mammal prey are described here.
Fishes utilize the soundscape and components of sound in their
environment to perform important functions such as foraging, predator
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009).
Depending on their hearing anatomy and peripheral sensory structures,
which vary among species, fishes hear sounds using pressure and
particle motion sensitivity capabilities and detect the motion of
surrounding water (Fay et al., 2008). The potential effects of noise on
fishes depends on the overlapping frequency range, distance from the
sound source, water depth of exposure, and species-specific hearing
sensitivity, anatomy, and physiology. Key impacts to fishes may include
behavioral responses, hearing damage, barotrauma (pressure-related
injuries), and mortality.
Fish react to sounds that 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 fishes (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.,
Pe[ntilde]a et al., 2013; Wardle et al., 2001; Jorgenson and Gyselman,
2009; Cott et al., 2012). More commonly, though, the impacts of noise
on fishes are temporary.
SPLs of sufficient strength have been known to cause injury to
fishes and fish mortality (summarized in Popper et al., 2014). 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. (2012b) showed that a TTS of
4 to 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.,
2012a; Casper et al., 2013, 2017).
Fish populations in the proposed project area that serve as marine
mammal prey could be temporarily affected by noise from impact pile
installation and vibratory pile removal. The frequency range in which
fishes generally perceive underwater sounds is 50 to 2,000 Hz, with
peak sensitivities below 800 Hz (Popper and Hastings, 2009). Fish
behavior or distribution may change, especially with strong and/or
intermittent sounds that could harm fishes. High underwater SPLs have
been documented to alter behavior, cause hearing loss, and injure or
kill individual fish by causing serious internal injury (Hastings and
Popper, 2005).
Zooplankton is a food source for several marine mammal species, as
well as a food source for fish that are then preyed upon by marine
mammals. Population effects on zooplankton could have indirect effects
on marine mammals. Data are limited on the effects of underwater sound
on zooplankton species, particularly sound from construction (Erbe et
al., 2019). Popper and Hastings (2009) reviewed information on the
effects of human-generated sound and concluded that no substantive data
are available on whether the sound levels from pile driving, seismic
activity, or any human-made sound would have physiological effects on
invertebrates. Any such effects would be limited to the area very near
(1 to 5 m) the sound source and would result in no population effects
because of the relatively small area affected at any one time and the
reproductive strategy of most zooplankton species (short generation,
high fecundity, and very high natural mortality). No adverse impact on
zooplankton populations is expected to occur from the specified
activity due, in part, to large reproductive capacities and naturally
high levels of predation and mortality of these populations. Any
mortalities or impacts that might occur would be negligible.
The greatest potential impact to marine mammal prey during
construction would occur during impact pile driving. In-water
construction activities would only be initiated during daylight hours,
allowing fish to forage and transit the project area undisturbed in the
evening. Vibratory pile extraction may elicit behavioral reactions from
fishes such as temporary avoidance of the area but is unlikely to cause
injuries to fishes or have persistent effects on local fish
populations. Construction would have minimal permanent and temporary
impacts on benthic invertebrate species, a marine mammal prey source.
In addition, it should be noted that the area in question is likely
low-quality habitat since it is already highly developed and
experiences a high level of anthropogenic noise from normal NSB Kings
Bay operations and other vessel traffic.
Potential Effects on Foraging Habitat
The TRF wharf interface repairs project is not expected to result
in any habitat-related effects that could cause significant or long-
term negative consequences for individual marine mammals or their
populations, since installation and removal of in-water piles would be
temporary and intermittent. The total seafloor area affected by pile
installation and removal is a very small area compared to the vast
foraging area available to marine mammals outside this project area.
NSB Kings Bay is a developed military installation that does not likely
provide high-quality habitat for prey species. The area impacted by the
proposed project is relatively small compared to the available habitat
outside the area. The proposed project overlaps with small portion of
the Small and Resident Population BIA designated for the SGES stock of
Tamanend's bottlenose dolphins. While this area is biologically
important to the stock, the maximum anticipated ensonified area is
approximately 1 km\2\, representing less and 1 percent of the 410 km\2\
BIA. 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. As described in the preceding, the
potential for the Navy's construction to affect the availability of
prey to marine mammals or to meaningfully impact the quality of
physical or acoustic habitat is considered to be insignificant.
Therefore, impacts of the project are not
[[Page 66308]]
likely to have adverse effects on marine mammal foraging habitat in the
proposed project area.
In summary, given the project area is an industrialized Navy base,
is a relatively small area being affected, as well as the temporary and
mostly transitory nature of the proposed construction activities, any
adverse effects from the Navy's activities on prey habitat or prey
populations are expected to be minor and temporary. The most likely
impact to fishes at the project site would be temporary avoidance of
the area. 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 preliminarily
conclude that impacts of the specified activities 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 of Marine Mammals
This section provides an estimate of the number of incidental takes
proposed for authorization through the IHA, which will inform NMFS'
consideration of ``small numbers,'' the negligible impact
determinations, and impacts on subsistence uses.
Harassment is the only type of take expected to result from these
activities. Except with respect to certain activities not pertinent
here, section 3(18) of the MMPA defines ``harassment'' as any act of
pursuit, torment, or annoyance, which: (i) has the potential to injure
a marine mammal or marine mammal stock in the wild (Level A
harassment); or (ii) has the potential to disturb a marine mammal or
marine mammal stock in the wild by causing disruption of behavioral
patterns, including, but not limited to, migration, breathing, nursing,
breeding, feeding, or sheltering (Level B harassment).
Authorized takes would be by Level B harassment only, in the form
behavioral reactions and/or TTS for individual marine mammals resulting
from exposure to vibratory pile extraction and impact pile driving.
Based on the nature of the activity and the anticipated effectiveness
of the mitigation measures (i.e., clearance and shutdown zones)
discussed in detail below in the Proposed Mitigation section, Level A
harassment is neither anticipated nor proposed to be authorized.
As described previously, no serious injury or mortality is
anticipated or proposed to be authorized for this activity. Below we
describe how the proposed take numbers are estimated.
For acoustic impacts, generally speaking, we estimate take by
considering: (1) acoustic criteria above which NMFS believes there is
some reasonable potential for marine mammals to be behaviorally
harassed or incur some degree of AUD INJ; (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) the number of days of activities. We note that while these
factors can contribute to a basic calculation to provide an initial
prediction of potential takes, additional information that can
qualitatively inform take estimates is also sometimes available (e.g.,
previous monitoring results or average group size). Below, we describe
the factors considered here in more detail and present the proposed
take estimates.
Acoustic Criteria
NMFS recommends the use of acoustic criteria 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 AUD INJ of some degree (equated to
Level A harassment). Criteria for AUD INJ, and hearing group categories
are available in NMFS' Updated Technical Guidance (NMFS, 2024) and are
reflected below in the Level A harassment section.
Level B Harassment--Though significantly driven by received level,
the onset of behavioral disturbance from anthropogenic noise exposure
is also informed to varying degrees by other factors related to the
source or exposure context (e.g., frequency, predictability, duty
cycle, duration of the exposure, signal-to-noise ratio, distance to the
source), the environment (e.g., bathymetry, other noises in the area,
predators in the area), and the receiving animals (hearing, motivation,
experience, demography, life stage, depth) and can be difficult to
predict (e.g., Southall et al., 2007; 2021; Ellison et al., 2012).
Based on what the available science indicates and the practical need to
use a threshold based on a metric that is both predictable and
measurable for most activities, NMFS typically uses a generalized
acoustic threshold based on received level to estimate the onset of
behavioral harassment. NMFS generally predicts that marine mammals are
likely to be behaviorally harassed in a manner considered to be Level B
harassment when exposed to underwater anthropogenic noise above root-
mean-squared sound pressure levels (RMS SPL) of 120 dB (referenced to 1
micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g.,
scientific sonar) sources. Generally speaking, take estimates by Level
B harassment are based on these behavioral harassment thresholds are
expected to include any likely takes by TTS as, in most cases, the
likelihood of TTS occurs at distances from the source less than those
at which behavioral harassment is likely. TTS of a sufficient degree
can manifest as behavioral harassment, as reduced hearing sensitivity
and the potential reduced opportunities to detect important signals
(conspecific communication, predators, prey) may result in changes in
behavior patterns that would not otherwise occur.
Navy's proposed activity includes the use of continuous (vibratory
pile removal) and impulsive (impact pile driving) sources, and
therefore the RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa are
applicable.
Level A Harassment--NMFS' Updated Technical Guidance for Assessing
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to
assess AUD INJ (Level A harassment) to five different underwater marine
mammal groups (based on hearing sensitivity) as a result of exposure to
noise from two different types of sources (impulsive or non-impulsive)
(table 5). Navy's proposed activity includes the use of impulsive
(impact driving) and non-impulsive (vibratory driving) sources.
The 2024 Updated Technical Guidance criteria include both updated
thresholds and updated weighting functions for each hearing group. The
thresholds are provided in the table below. The references, analysis,
and methodology used in the development of the criteria are described
in NMFS' 2024 Updated Technical Guidance, which may be accessed at:
<a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools</a>.
[[Page 66309]]
Table 5--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
AUD INJ Onset Acoustic Thresholds * (received level)
Hearing group ------------------------------------------------------------------------
Impulsive Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans........... Cell 1: Lpk,flat: 222 dB; Cell 2: LE,LF,24h: 197 dB.
LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans.......... Cell 3: Lpk,flat: 230 dB; Cell 4: LE,HF,24h: 201 dB.
LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans.... Cell 5: Lpk,flat: 202 dB; Cell 6: LE,VHF,24h: 181 dB.
LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater)..... Cell 7: Lpk,flat: 223 dB; Cell 8: LE,PW,24h: 195 dB.
LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater).... Cell 9: Lpk,flat: 230 dB; Cell 10: LE,OW,24h: 199 dB.
LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
impulsive sources.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
exposure level (LE,p) has a reference value of 1 [micro]Pa\2\s. In this table, criteria are abbreviated to be
more reflective of International Organization for Standardization standards (ISO, 2017). The subscript
``flat'' is being included to indicate peak sound pressure are flat weighted or unweighted within the
generalized hearing range of marine mammals underwater (i.e., 7 Hz to 165 kHz). The subscript associated with
cumulative sound exposure level criteria indicates the designated marine mammal auditory weighting function
(LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is 24 hours.
The weighted cumulative sound exposure level criteria 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 criteria will be exceeded.
Ensonified Area
Here, we describe operational and environmental parameters of the
activity that are used in estimating the area ensonified above the
acoustic thresholds, including source levels and transmission loss (TL)
coefficient.
The source levels assumed for pile installation and removal are
based on reviews of measurements of the same or similar types and
dimensions from similar coastal construction projects (table 6).
Table 6--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
Extraction and RMS SPL (dB re SEL (dB re 1 Peak SPL (dB
Pile size and type driving method 1 [mu]Pa) [mu]Pa2-sec) re 1 [mu]Pa) Reference
----------------------------------------------------------------------------------------------------------------
14-inch square steel H piles. Vibratory 150 NA NA Caltrans
Extraction. (2020).
20-inch square concrete piles Impact Driving.. 177 164 189 Caltrans
(2020).
----------------------------------------------------------------------------------------------------------------
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 x Log10(R1/R2),
where:
TL = transmission loss in dB,
B = transmission loss coefficient,
R1 = the distance of the modeled SPL from the driven pile, and
R2 = the distance from the driven pile of the initial
measurement.
This formula neglects loss due to scattering and absorption, which
is assumed to be zero here. The degree to which underwater sound
propagates away from a sound source depends on various factors, most
notably the water bathymetry and the presence or absence of reflective
or absorptive conditions, including in-water structures and sediments.
Spherical spreading occurs in a perfectly unobstructed (free-field)
environment not limited by depth or water surface, resulting in a 6-dB
reduction in sound level for each doubling of distance from the source
(20*log[range]). Cylindrical spreading occurs in an environment in
which sound propagation is bounded by the water surface and sea bottom,
resulting in a reduction of 3 dB in sound level for each doubling of
distance from the source (10*log[range]). A practical spreading value
of 15 is often used in shallow-water coastal conditions, such as those
found in the East River at NSB King Bay. In these environments, sound
waves repeatedly reflect off the surface and bottom, reflecting an
expected propagation environment between spherical and cylindrical
spreading-loss conditions.
Site-specific TL data for the East River is not available;
therefore, the default coefficient of 15 is used to calculate distances
to the Level A harassment and Level B harassment thresholds. Assuming
practicable spreading and other assumptions regarding the source
characteristics and operational logistics (e.g., source level, number
of strikes per pile, number of piles per day), the Navy and NMFS
calculated distances to the Level A harassment and Level B harassment
thresholds and associated ensonified areas. Because an ensonified area
associated with Level A harassment is more technically challenging to
predict given the accounting for a cumulative energy component that
changes over time, to assist applicants in assessing the potential for
Level A harassment without the need for complex modeling, NMFS
developed an optional User Spreadsheet tool to accompany the 2024
Updated Technical Guidance (see <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools">https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools</a>). This relatively simple tool can be used
to calculate a Level A harassment isopleth distance for use in
conjunction with marine mammal density or occurrence data to predict
the amount of take that may occur incidental to an activity. We note
that, because of some of the assumptions in the methods underlying this
spreadsheet tool, we anticipate that the resulting isopleths would
typically be overestimates, which may lead to an overestimate of
potential exposures from Level A harassment. However, this optional
tool offers the best way to estimate isopleth distances when more
[[Page 66310]]
sophisticated modeling methods are not available or practical. For
stationary sources such as vibratory pile removal and impact pile
driving, the optional User Spreadsheet tool predicts the distance at
which, if a marine mammal remained at that distance for the duration of
the activity, it would be expected to incur AUD INJ. Inputs used in the
optional User Spreadsheet tool (table 7), and the resulting estimated
isopleths (table 8), are reported below.
Table 7--NMFS User Spreadsheet Inputs for the Navy's TRF Wharf Interface Repairs Project
--------------------------------------------------------------------------------------------------------------------------------------------------------
Activity
duration/ Distance of
Weighting TL pile sound pressure
Pile size and material Spreadsheet tab used Source level (SPL) factor coefficient Piles/day (minutes), level
adjustment or (strikes/ measurement (m)
pile)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Vibratory pile removal
--------------------------------------------------------------------------------------------------------------------------------------------------------
14-inch square steel H pile........ A.1) Vibratory Pile 150 dB RMS........... 2.5 15 \A\ 8 10 10
Driving. \B\ 4
--------------------------------------------------------------------------------------------------------------------------------------------------------
Impact pile driving
--------------------------------------------------------------------------------------------------------------------------------------------------------
20-inch inch square concrete piles. E.1) Impact Pile 177 dB RMS, 164 dB 2 15 4 500 10
Driving. SEL, 189 dB PK.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\A\ 14-inch square steel H-piles at the east and west wharf will be removed at a maximum rate of 8 piles/day.
\B\ 14-inch square steel H-piles at the east wharf dolphin pier will be removed at a maximum rate of 4 piles/day to maintain the structural integrity of
the existing dolphin pier.
Table 8--Projected Distances to Level A Harassment and Level B Harassment Isopleths (m) by Marine Mammal Hearing
Group for Vibratory Removal and Impact Installation
----------------------------------------------------------------------------------------------------------------
Level A harassment Level B harassment
distance (m) distance (m)
Project component Pile size and material -------------------------------------------
High frequency
cetaceans All marine mammals
----------------------------------------------------------------------------------------------------------------
Vibratory pile removal
----------------------------------------------------------------------------------------------------------------
East and West Wharf..................... .......................... \A\ 0.8 1,000
East Wharf Dolphin Pier................. 14-inch square steel H \B\ 0.5 ....................
pile.
----------------------------------------------------------------------------------------------------------------
Impact pile driving
----------------------------------------------------------------------------------------------------------------
East Wharf, West Wharf, and East Wharf 20-inch inch square 10.9 135.9
Dolphin Pier. concrete piles.
----------------------------------------------------------------------------------------------------------------
\A\ 14-inch square steel H-piles at the east and west wharf will be removed at a maximum rate of 8 piles/day.
\B\ 14-inch square steel H-piles at the east wharf dolphin pier will be removed at a maximum rate of 4 piles/day
to maintain the structural integrity of the existing dolphin pier.
Marine Mammal Occurrence and Take Estimation
In this section, we provide information regarding the occurrence of
marine mammals in the project area, including density and site-specific
observational data, to inform the take calculations.
SMEs stationed at NSB Kings Bay informed the Navy that two to three
groups of dolphins are observed each day year-round in the immediate
vicinity of the TRF wharf interface repairs project. Group sizes during
these observations typically range from three to four individuals per
group. Similarly, Speakman et al. (2023) conducted vessel-based photo-
identification surveys from Altamaha Sound to Cumberland Sound from
2010 through 2021. Based on cluster analysis, five distinct social
clusters were identified within the SGES stock, with an overall mean
group size of 6.7 dolphins across all five clusters. The utilization
distributions of clusters 1 and 2 were located closest to the project
area, with mean group sizes of 5.1 and 5.5 individuals, respectively.
Although data from Speakman et al. (2023) indicate that local
cluster group sizes range from 5.1 to 5.5 individuals, site-specific
observational data from NSB Kings Bay indicates a typical maximum group
size of four individuals. Considering the availability of site-specific
observational data, the Navy proposed to estimate take assuming a group
size of four dolphins and that two groups of dolphins could transit
through the project area each day. NMFS evaluated the data from
Speakman et al. (2023) along with the observational data from NSB Kings
Bay and preliminarily concurs that the Navy's approach for estimating
dolphin occurrence in the project area during the proposed activities
is appropriate.
Take by Level B harassment was calculated using the following
formula:
Level B Harassment = Group Size (4) x Groups/Day(2) x Vibratory Pile
Removal and Impact Pile Driving Days (54)
Therefore, the total estimated take equates to 432 takes of
Tamanend's bottlenose dolphins by Level B harassment.
Take by Level A harassment of marine mammals is not expected to
occur during the specified activities. The largest modeled Level A
harassment distance would occur during impact driving of four 20-inch
square concrete piles (10.9 m for high-frequency cetaceans) (table 8).
During construction, the Navy proposes to implement a 15-m clearance
zone prior to the start of construction and 15-m shutdown zone for both
vibratory pile removal and impact pile driving. It is highly unlikely
that any Tamanend's
[[Page 66311]]
bottlenose dolphins would enter and remain within the relatively small
Level A harassment distance long enough to incur an AUD INJ.
Considering that the Navy did not request take by Level A harassment
and that it is highly unlikely an animal would remain within such a
small area, NMFS does not expect take by Level A harassment to occur.
Therefore, take by Level A harassment of Tamanend's bottlenose dolphins
is not expected and is not proposed for authorization.
Table 9--Proposed Take by Level B Harassment for the Navy's TRF Wharf Interface Repairs Project
----------------------------------------------------------------------------------------------------------------
Take as a
Species Stock Level B percentage of the
harassment stock
----------------------------------------------------------------------------------------------------------------
Tamanend's Bottlenose Dolphin.............. Southern Georgia Estuarine... 432 (\A\)
----------------------------------------------------------------------------------------------------------------
\A\ A reliable abundance estimate is not available for this stock. However, across 163 surveys from 2010 to 2021
within the SGES stock range, 768 distinctively marked individual dolphins were photo-identified, representing
57 percent of all observed dolphins, and the growth curve did not asymptote (Speakman et al., 2023).
Proposed Mitigation
In order to issue an IHA under section 101(a)(5)(D) of the MMPA,
NMFS must set forth the permissible methods of taking pursuant to the
activity, and other means of effecting the least practicable impact on
the species or stock and its habitat, paying particular attention to
rookeries, mating grounds, and areas of similar significance, and on
the availability of the species or stock for taking for certain
subsistence uses (latter not applicable for this action). NMFS
regulations require applicants for incidental take authorizations to
include information about the availability and feasibility (economic
and technological) of equipment, methods, and manner of conducting the
activity or other means of effecting the least practicable adverse
impact upon the affected species or stocks, and their habitat (50 CFR
216.104(a)(11)).
In evaluating how mitigation may or may not be appropriate to
ensure the least practicable adverse impact on species or stocks and
their habitat, as well as subsistence uses where applicable, NMFS
considers two primary factors:
(1) The manner in which, and the degree to which, the successful
implementation of the measure(s) is expected to reduce impacts to
marine mammals, marine mammal species or stocks, and their habitat.
This considers the nature of the potential adverse impact being
mitigated (likelihood, scope, range). It further considers the
likelihood that the measure will be effective if implemented
(probability of accomplishing the mitigating result if implemented as
planned), the likelihood of effective implementation (probability
implemented as planned); and
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost and impact on
operations.
The mitigation requirements described in the following were
proposed by the Navy in its adequate and complete application or are
the result of subsequent coordination between NMFS and the Navy. The
Navy has agreed that all of the mitigation measures are practicable.
NMFS has fully reviewed the specified activities and the mitigation
measures to determine if the mitigation measures would result in the
least practicable adverse impact on marine mammals and their habitat,
as required by the MMPA, and has determined the proposed measures are
appropriate. NMFS describes these below as proposed mitigation
requirements and has included them in the proposed IHA. These measures
must be adhered to unless in the case of human safety concerns or pile
refusal/instability.
Pre- and Post-Activity Monitoring
Prior to the start of daily in-water construction activities, or
whenever a break in pile driving of 30 minutes or longer occurs,
Protected Species Observers (PSOs) would observe for marine mammals at
least 30 minutes (pre-clearance monitoring) through 30 minutes post-
completion of pile removal or pile driving activities. Pre-start
clearance monitoring must be conducted during periods of visibility
sufficient for the PSOs to determine that the clearance zones indicated
in table 10 are clear of marine mammals.
Soft Start Procedures for Impact Driving
Soft-start procedures provide additional protection to marine
mammals by providing warning and/or giving marine mammals a chance to
leave the area prior to the hammer operating at full capacity. The Navy
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. Soft start is not applicable to vibratory pile removal.
Clearance and Shutdown Zones
For pile installation and removal activities, the Navy proposes to
implement clearance and shutdown zones with radial distance of 15 m.
The purpose of clearance and shutdown zones is to reduce the
probability or scope of proximal acute impacts by taking steps in real
time (i.e., delay commencement of or stopping an activity) once a
higher-risk scenario is identified. If a marine mammal is observed
within a clearance or shutdown zone, or if a marine mammal enters or is
observed within the clearance or shutdown zone while construction is
ongoing, pile driving or pile removal must be delayed or halted.
Operations may only resume once the animal is visually confirmed
outside the zone or 15 minutes have passed without a re-detection.
Construction supervisors and crews, PSOs, and relevant Navy staff
must avoid direct physical interaction with marine mammals during
construction activities. If marine mammals come within 10 m of such
activity, operations must cease, to avoid direct interaction. If an
activity 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
indicated in table 10, or 15 minutes have passed without re-detection
of the animal.
Finally, construction activities must be halted upon observation of
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 any clearance or shutdown zone.
If a marine mammal
[[Page 66312]]
species not covered under the IHA enters a clearance or shutdown zone,
all in-water activities would cease until the animal leaves the zone or
has not been observed for at least 15 minutes. Pile driving may proceed
if the unauthorized species is observed leaving the clearance and
shutdown zone or if 15 minutes have passed since the last observation.
Table 10--Proposed Clearance, Shutdown and Level B Harassment Zones (m)
----------------------------------------------------------------------------------------------------------------
Clearance and shutdown zones Level B harassment zones (m)
(m) -----------------------------
Pile size, type, and method ------------------------------
High Frequency Cetaceans All Marine Mammals
----------------------------------------------------------------------------------------------------------------
14-inch, square steel H piles, vibratory removal.... 15 1000
20-inch square concrete piles, impact pile driving.. 15 140
----------------------------------------------------------------------------------------------------------------
Protected Species Observers
The number and placement of PSOs during all construction activities
(described in the Proposed Monitoring and Reporting section) would be
designed to ensure that the entire shutdown zone is visible. The Navy
would employ a minimum of one PSO for impact pile driving and three
PSOs would be on duty during all vibratory pile extraction activities
for the TRF wharf interface repairs project.
Based on our evaluation of the applicant's proposed measures, NMFS
has preliminarily determined that the proposed mitigation measures
provide the means of 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 while
conducting the activities. Effective reporting is critical both to
compliance as well as ensuring that the most value is obtained from the
required monitoring.
Monitoring and reporting requirements prescribed by NMFS should
contribute to improved understanding of one or more of the following:
<bullet> Occurrence of marine mammal species or stocks in the area
in which take is anticipated (e.g., presence, abundance, distribution,
density);
<bullet> Nature, scope, or context of likely marine mammal exposure
to potential stressors/impacts (individual or cumulative, acute or
chronic), through better understanding of: (1) action or environment
(e.g., source characterization, propagation, ambient noise); (2)
affected species (e.g., life history, dive patterns); (3) co-occurrence
of marine mammal species with the activity; or (4) biological or
behavioral context of exposure (e.g., age, calving or feeding areas);
<bullet> Individual marine mammal responses (behavioral or
physiological) to acoustic stressors (acute, chronic, or cumulative),
other stressors, or cumulative impacts from multiple stressors;
<bullet> How anticipated responses to stressors impact either: (1)
long-term fitness and survival of individual marine mammals; or (2)
populations, species, or stocks;
<bullet> Effects on marine mammal habitat (e.g., marine mammal prey
species, acoustic habitat, or other important physical components of
marine mammal habitat); and
<bullet> Mitigation and monitoring effectiveness.
The monitoring and reporting requirements described in the
following were proposed by Navy in its adequate and complete
application and are the result of subsequent coordination between NMFS
and Navy. The Navy has agreed to the requirements. NMFS describes these
below as requirements and has included them in the proposed IHA.
To ensure strict adherence to all terms and conditions of the
proposed authorization and to guarantee that all monitoring and
reporting requirements are diligently met, the Navy has established
enhanced internal administrative and oversight protocols. A natural
resources specialist at Naval Facilities Engineering Systems Command,
Southeast (NAVFAC SE) will maintain and share a consolidated master
list of all relevant points of contact, mitigating risks associated
with staff turnover and ensuring project notifications consistently
reach the correct personnel. Prior to the start of construction, the
assigned specialist will conduct a dedicated on-site meeting with
project-level personnel to review specific permit requirements and
establish a fixed, calendar-based schedule for the delivery of
monitoring reports for review. Additionally, quarterly conferences
between NAVFAC SE and Office of the Chief of Naval Operations staff
will provide leadership with regular status updates and promptly
address any perceived issues.
All PSOs must be NMFS-approved and have no other assigned tasks
during monitoring periods. At least one PSO would have prior experience
performing the duties of a PSO during construction activity pursuant to
a NMFS-issued ITA.
During all vibratory pile removal and impact pile driving for the
Navy's TRF wharf interface repairs project, PSOs would monitor from
various stations around the project area (see figures 8 through 18 in
section 5.2 of the Navy's application). PSOs would document marine
mammal presence and behavior. During vibratory pile extraction, a
minimum of three PSOs will monitor for marine mammals from stations
shown in figures 10, 11, 14, 15, 18, and 19 of the Navy's application.
During impact pile driving, a minimum of one PSO will monitor for
marine mammals from the pile driving location. For activities requiring
multiple PSOs, if the stations presented in figures 8 through 19 of the
Navy's application do not provide adequate visual coverage of the
required clearance, shutdown, and Level A and Level B harassment zones,
the Navy will select alternative land-based monitoring stations that
meet the criteria described above.
Monitoring would be conducted 30 minutes before, during, and 30
minutes after the specified activities. Additionally, PSOs would record
all incidents of marine mammal occurrence, regardless of distance from
activity, and would document any
[[Page 66313]]
behavioral reactions in concert with distance from piles being driven
or removed. Pile driving activities include the time installing or
removing a single pile or series of piles, as long as the time elapsed
between uses of the pile driving equipment is no more than 30 minutes.
The Navy would abide by all monitoring and reporting measures
contained within the IHA, if issued, and their Protected Species
Monitoring and Mitigation Plans (see NMFS' website at <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>). NMFS describes these
below as requirements and has included them in the proposed IHA.
Reporting
The Navy would be required to submit a draft report(s) on all
construction activities and marine mammal monitoring results to NMFS
within 90 days of the completion of monitoring, or 60 days prior to the
requested issuance of any subsequent IHAs or similar activity at the
same location, whichever comes first. The information required to be
collected and reported to NMFS is included in the draft IHA available
at <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>. In summary, the
report would include, but not be limited to, information regarding
activities that occurred, marine mammal sighting data, and whether
mitigative actions were taken or could not be taken. The Navy would
also be required to submit reports on any observed injured or dead
marine mammals. If the death or injury was clearly caused by the
specified activity, the Navy would 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 Navy
would not resume its activities until notified by NMFS.
Specific proposed mitigation, monitoring, and reporting
requirements can be found in the draft IHAs found at <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>.
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 impacts or responses (e.g., intensity, duration),
the context of any impacts or responses (e.g., critical reproductive
time or location, foraging impacts affecting energetics), as well as
effects on habitat, and the likely effectiveness of the mitigation. We
also assess the number, intensity, and context of estimated takes by
evaluating this information relative to population status. Consistent
with the 1989 preamble for NMFS' 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 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).
NMFS has identified key factors which may be employed to assess the
level of analysis necessary to conclude whether potential impacts
associated with a specified activity should be considered negligible.
These include, but are not limited to, the type and magnitude of
taking, the amount and importance of the available habitat for the
species or stock that is affected, the duration of the anticipated
effect to the species or stock, and the status of the species or stock.
The potential effects of the specified activities on Tamanend's
bottlenose dolphins are discussed below.
Pile driving and pile removal associated with the Navy's TRF wharf
interface repairs project, as outlined previously, have the potential
to disturb or displace marine mammals. Specifically, the specified
activities may result in incidental take, in the form of Level B
harassment only, from underwater sounds generated by pile driving and
pile removal. Potential takes could occur if dolphins are present in
zones ensonified above the threshold for Level B harassment identified
above while activities are underway.
The Navy's proposed activities and associated impacts would occur
within a limited, confined area of the stocks' range. In-water work
would occur in the vicinity of the NSB Kings Bay, and sound from the
specified would be blocked by the shoreline of Crab Island and the East
River. The intensity and duration of take by Level B harassment would
be minimized through use of mitigation measures described herein.
Further, the presence of dolphins in the area is expected to be
limited, as the NSB Kings Bay is a military facility that experiences
high levels of military vessel traffic. Dolphins that occur within the
project area are expected to primarily transit through the East River,
thereby reducing the potential for prolonged exposure or behavioral
disturbance. In addition, NMFS does not anticipate that serious injury
or mortality will occur as a result of the Navy's proposed activities
given the nature of the activities, even in the absence of required
mitigation.
Effects on individuals that are taken by Level B harassment in the
form of behavioral disruption, on the basis of reports in the
literature as well as monitoring from other similar activities, will
likely be limited to reactions such as avoidance, increased swimming
speeds, increased surfacing time, or decreased foraging (if such
activity were occurring) (e.g., Ridgway et al., 1997; Nowacek et al.,
2007; Thorson and Reyff, 2006; Kendall and Cornick, 2015; Goldbogen et
al., 2013b; Blair et al., 2015; Wisniewska et al., 2016; Piwetz et al.,
2021). Most likely, individuals would simply move away from the sound
source and temporarily avoid the area where pile driving is occurring.
If sound produced by project activities is sufficiently disturbing,
animals are likely to simply avoid the area while the activities are
occurring, particularly as the project is located at naval base that
experiences high levels of military vessel traffic. We expect that any
avoidance of the project area by dolphins would be temporary in nature
and that any marine mammals that avoid the project area during
construction would not be permanently displaced. In-water construction
would be limited to daylight hours from 1 hour after sunrise to 1 hour
before sunset; thus, dolphins would be able to transit through or
forage in the project area at night when construction activities are
inactive. Therefore, short-term avoidance of the project area and
energetic impacts of interrupted foraging or other important behaviors
is unlikely to affect the reproduction or survival of individual marine
mammals, and the effects of behavioral disturbance on individuals is
not likely to accrue in a manner that would affect the rates of
[[Page 66314]]
recruitment or survival of any affected stock.
In addition to behavioral disturbances, exposure to elevated
underwater sound levels may result in TTS or acoustic masking in some
individuals present within the ensonified areas. Any TTS or masking
experienced by dolphins would be low-level, short-term, and fully
recoverable upon leaving the area. While minor acoustic masking or
temporary reductions in hearing sensitivity could briefly interfere
detections of acoustic cues, such as social communication whistles or
echolocation clicks used for foraging, these effects would be localized
and brief. Because pile driving is intermittent, acoustic masking and
TTS will not disrupt communication or foraging to a degree that would
cause chronic stress or affect individual health, survival, or
reproduction.
As stated in the Monitoring and Reporting section, the Navy would
implement shutdown zones. No take by Level A harassment is proposed for
authorization and thus is not expected to adversely impact individual
fitness, let alone annual rates of recruitment or survival for the
affected species or stock.
This project is also not expected to have significant adverse
effects on affected marine mammals' habitats. The project activities
will not modify existing marine mammal habitat for a significant amount
of time. The activities may cause some fish to leave the area of
disturbance, thus temporarily impacting marine mammals' foraging
opportunities in a limited portion of the foraging range. However,
given the short duration of the activities and the relatively small
area of the habitat that may be affected, the impacts to marine mammal
habitat are not expected to cause significant or long-term negative
consequences.
Tamanend's bottlenose dolphins are common in the project area, with
SMEs at NSB Kings Bay observing two to three groups of dolphins each
day with group sizes ranging from three to four individuals per group.
Speakman et al. (2023) conducted bottlenose dolphin surveys from the
Altamaha Sound to the Cumberland Sound from 2010 through 2021,
encompassing the range of the SGES stock. Analyses of these 163 surveys
identified 5 distinct social clusters with minimal spatial overlap in
habitat use. The core range of only one social cluster was located 2
nmi from the project site. Frequent sightings of bottlenose dolphins by
NSB Kings Bay SMEs, combined with data from Speakman et al. (2023),
indicate that project activities will primarily affect this single
social cluster, with some individuals likely transiting the project
area repeatedly.
While the total number of takes proposed for authorization
represents a notable proportion of SGES stock bottlenose dolphins, the
majority of these exposures are expected to occur within this single
social cluster whose core range is near the project site. Consequently,
the requested take does not represent a broad impact to the entire
stock, but rather repeated exposures of the same individuals. Although
this social cluster may experience frequent exposures to elevated
underwater sound levels, such intermittent disturbances are not
expected to result in chronic stress or physical injury that would
reduce the fitness, survival, or reproductive success of any
individual. Animals from this social cluster are expected to
temporarily avoid or quickly transit through the active project area
during in-water construction, minimizing their exposure duration.
Furthermore, the ensonified areas affect only a small portion of their
overall habitat, leaving the majority of their core range undisturbed,
and in-water construction will occur intermittently over 54 non-
consecutive days during daylight hours rather than continuously.
Because the anticipated impacts are localized to a small subset of the
population and are not expected to affect the health or fitness of
those individuals, the take proposed to be authorized will not affect
annual rates of recruitment or survival for the SGES stock of
Tamanend's bottlenose dolphins.
The Navy's TRF wharf interface repairs project is situated within
the Small and Resident Population BIA for SGES stock of Tamanend's
bottlenose dolphins. The area from the Altamaha Sound to the Cumberland
Sound is designated as a Small and Resident Population BIA for SGES
stock of Tamanend's bottlenose dolphins due to their limited geographic
range. The ensonified areas from the specified activities are
relatively small, representing less than 1 percent of the 410 km\2\
area of the BIA. Therefore, ample high-quality habitat remains
available to dolphins in the areas surrounding the East River to
support individuals that may be temporarily displaced. Because the
acoustic stressors occur intermittently and the physical footprint of
the project is localized, the disturbance within the Small and Resident
Population BIA will be short-term in duration and spatially confined.
Consequently, the proposed action is not expected to diminish the value
or functional role of the habitat within the BIA for the SGES stock of
Tamanend's bottlenose dolphins, and the overall effects on the
designated BIA are expected to be de minimis.
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 any of the species
or stocks through effects on annual rates of recruitment or survival:
<bullet> No Level A harassment, serious injury or mortality is
anticipated or proposed to be authorized;
<bullet> Proposed take by Level B harassment does not represent a
broad, stock-wide impact, but rather repeated, low-level exposures to a
single social cluster whose core range is adjacent to the project site;
<bullet> Level B harassment would be primarily in the form of
behavioral disturbance, resulting in avoidance of the project area
around where impact pile driving and vibratory pile removal are
occurring;
<bullet> Some temporary low-level TTS or acoustic masking may
occur, briefly limiting the detection of acoustic cues (such as social
communication whistles and echolocation) for short durations within a
confined footprint, but these effects will be fully recoverable and
will not affect individual fitness or survival;
<bullet> Behavioral disturbance will be temporary and localized;
while dolphins may briefly avoid or quickly transit active work zones
during pile driving, intermittent pauses during daylight hours and
complete shutdown at night ensure continuous opportunities for
undisturbed transiting and foraging;
<bullet> The ensonified areas, and project area in general, are
small relative to the overall habitat of the SGES stock of Tamanend's
bottlenose dolphins, and acoustic impacts within the Small and Resident
Population BIA will be spatially minimal and short in duration, with
construction occurring only over 54 non-consecutive days;
<bullet> Nearby areas of similar habitat value around the East
River and the Cumberland Sound are available for marine mammals that
may temporarily avoid the project area during construction activities;
and
<bullet> Effects on marine mammal habitat and prey will be short-
term and localized, causing no significant or long-term negative
consequences to foraging success or population fitness.
Based on the analysis contained herein of the likely effects of the
specified activity on marine mammals and their habitat, and taking into
consideration the implementation of the proposed monitoring and
mitigation measures, NMFS preliminarily finds
[[Page 66315]]
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 previously, only take of small numbers of marine mammals
may be authorized under section 101(a)(5)(A) and (D) of the MMPA for
specified activities other than military readiness activities. The MMPA
does not define small numbers and so, in practice, where estimated
numbers are available, NMFS compares the number of individuals taken to
the most appropriate estimation of abundance of the relevant species or
stock in our determination of whether an authorization is limited to
small numbers of marine mammals. When the predicted number of
individuals to be taken is fewer than one-third of the species or stock
abundance, the take is considered to be of small numbers (86 FR 5322,
January 19, 2021). Additionally, other qualitative factors may be
considered in the analysis, such as the temporal or spatial scale of
the activities.
The total abundance of the SGES stock of Tamanend's bottlenose
dolphins is unknown in current NMFS Stock Assessment Reports because
existing estimates are over 8 years old. However, empirical photo
identification data provides the best available information regarding
the minimum number of individuals residing within the geographic range
of the SGES stock and establishes a baseline for the small numbers
analysis. Across 163 surveys conducted between 2010 and 2021, Speakman
et al. (2023) cataloged 768 distinctly marked individuals, accounting
for 57 percent of the total individuals observed. Because the
cumulative discovery curve did not reach an asymptote and the
distinctively marked individuals represent only 57 percent of those
observed, the total population size of the SGES stock is expected to
exceed 768 individuals.
The best available science indicates that a much smaller number of
unique individuals than the majority of the stock would be exposed
repeatedly over the project duration. In-water construction for the
proposed project will occur within a very small geographic area over 54
non-consecutive days. The geographic range for the SGES stock extends
from the Altamaha Sound in the north to the Cumberland Sound in the
south. This area is designated as a Small and Resident Population BIA
for the SGES stock and encompasses an area over 410 km\2\. The largest
ensonified area from proposed project activities is approximately 1
km\2\, which represents less than 1 percent of the SGES stock's overall
geographic range.
Speakman et al. (2023) demonstrated that individuals identified
during the 2010 through 2023 surveys are partitioned into five distinct
social clusters, each exhibiting strong site fidelity with minimal
spatial overlap of core areas. The proposed projects action area is
located approximately 2 nmi from the core distribution of only one of
these five social structures (Speakman et al. 2023). The remaining four
social clusters reside further from the project footprint and are not
expected to occur in the action area or be incidentally taken during
the specified activities. High site fidelity indicates that dolphins
from cluster 2 may experience repeated daily exposures over the 54 days
of in water work, resulting in 432 instances of take, while the actual
number of unique individuals impacted remains small.
Because the specified activity is restricted to a small geographic
area relative to the SGES stock's range, and because dolphins in this
this stock exhibit strong site fidelity within their core range, only
one of five social clusters are likely to be within the project area.
Considering these factors, it is reasonable to conclude that the number
of unique individuals taken constitutes a small number of unique
individuals taken constitutes a small number, representing less than
one-third of the SGES stock population. Based on the analysis contained
herein of the proposed activity (including the proposed mitigation and
monitoring measures) and the anticipated take of marine mammals, NMFS
preliminarily finds that small numbers of marine mammals would be taken
relative to the population size of the affected species or stocks.
Unmitigable Adverse Impact Analysis and Determination
There are no relevant subsistence uses of the affected marine
mammal stocks or species implicated by this action. Therefore, NMFS has
determined that the total taking of affected species or stocks would
not have an unmitigable adverse impact on the availability of such
species or stocks for taking for subsistence purposes.
Endangered Species Act
Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.)
requires that each Federal agency ensures 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 incidental take
authorizations, NMFS consults internally whenever we propose to
authorize take for ESA-listed 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 Navy for the TRF wharf interface repairs project in
the East River at NSB Kings Bay, Georgia, provided the previously
mentioned mitigation, monitoring, and reporting requirements are
incorporated. A draft of the proposed IHA can be found at: <a href="https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities">https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities</a>.
Request for Public Comments
We request comment on our analyses, the proposed authorization, and
any other aspect of this notice. We also request 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 notice 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 notice is planned or (2) the activities as
described in the Description of Proposed Activity section of this
notice would not be completed by the time the IHA expires and a renewal
would allow for completion of the activities beyond that described in
the Dates and Duration section of this notice, provided all of the
following conditions are met:
<bullet> A request for renewal is received no later than 60 days
prior to the needed renewal IHA effective date (recognizing that the
renewal IHA expiration date cannot extend beyond 1 year from expiration
of the initial IHA).
<bullet> The request for renewal must include the following:
1. An explanation that the activities to be conducted under the
requested renewal IHA are identical to the activities analyzed under
the initial IHA, are a subset of the activities, or
[[Page 66316]]
include changes so minor (e.g., reduction in pile size) that the
changes do not affect the previous analyses, mitigation and monitoring
requirements, or take estimates (with the exception of reducing the
type or amount of take).
2. A preliminary monitoring report showing the results of the
required 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.
<bullet> 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 15, 2026.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2026-21419 Filed 10-19-26; 8:45 am]
BILLING CODE 3510-22-P
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