Notice2026-07295
Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to the Aak'w Landing Development Project in Juneau, Alaska
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
April 15, 2026
Issuing agencies
Commerce DepartmentNational Oceanic and Atmospheric Administration
Abstract
NMFS has received a request from Turnagain Marine Construction (TMC) for authorization to take marine mammals incidental to the Aak'w Landing Development Project in Juneau, Alaska. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to issue the requested Incidental Harassment Authorization (IHA). NMFS is also requesting comments on a possible one-time, 1-year renewal of the IHA, if issued, under certain circumstances, provided 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 IHA. Agency responses to substantive public comments received in response to this notice will be summarized in the final notice of our decision.
Full Text
<html>
<head>
<title>Federal Register, Volume 91 Issue 72 (Wednesday, April 15, 2026)</title>
</head>
<body><pre>
[Federal Register Volume 91, Number 72 (Wednesday, April 15, 2026)]
[Notices]
[Pages 20110-20137]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-07295]
-----------------------------------------------------------------------
DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
[RTID 0648-XF521]
Takes of Marine Mammals Incidental to Specified Activities;
Taking Marine Mammals Incidental to the Aak'w Landing Development
Project in Juneau, Alaska
AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and
Atmospheric Administration (NOAA), Commerce.
ACTION: Notice; proposed incidental harassment authorization; request
for comments.
-----------------------------------------------------------------------
SUMMARY: NMFS has received a request from Turnagain Marine Construction
(TMC) for authorization to take marine mammals incidental to the Aak'w
Landing Development Project in Juneau, Alaska. Pursuant to the Marine
Mammal Protection Act (MMPA), NMFS is requesting comments on its
proposal to issue the requested Incidental Harassment Authorization
(IHA). NMFS is also requesting comments on a possible one-time, 1-year
renewal of the IHA, if issued, under certain circumstances, provided
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 IHA. Agency responses
to substantive public comments received in response to this notice will
be summarized in the final notice of our decision.
DATES: Comments and information must be received no later than May 15,
2026.
ADDRESSES: Comments should be addressed to the Permits and Conservation
Division, Office of Protected Resources, National Marine Fisheries
Service, and should be submitted via email to <a href="/cdn-cgi/l/email-protection#79302d29573d1815003917161818571e160f"><span class="__cf_email__" data-cfemail="5b120f0b751f3a37221b35343a3a753c342d">[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 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: Jaclyn Daly, 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
[[Page 20111]]
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). Further, 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 (collectively referred to as
``mitigation''); and requirements pertaining to the monitoring and
reporting of the takings. The definitions of all applicable MMPA terms
are included below (see also 16 U.S.C. 1362; 50 CFR 216.103).
<bullet> U.S. Citizen--individual U.S. citizens or any corporation
or similar entity if it is organized under the laws of the United
States or any governmental unit defined in 16 U.S.C. 1362(13); 50 CFR
216.103);
<bullet> Take--to harass, hunt, capture, or kill, or attempt to
harass, hunt, capture, or kill any marine mammal (16 U.S.C. 1362(13);
50 CFR 216.3);
<bullet> Incidental harassment, Incidental taking, and incidental,
but not intentional, taking--an accidental taking. This does not mean
that the taking is unexpected, but rather it includes those takings
that are infrequent, unavoidable or accidental (50 CFR 216.103);
<bullet> Level A harassment--any act of pursuit, torment, or
annoyance which has the potential to injure a marine mammal or marine
mammal stock in the wild (16 U.S.C. 1362(18); 50 CFR 216.3);
<bullet> Level B harassment--any act of pursuit, torment, or
annoyance which 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 (16 U.S.C. 1362(18); 50 CFR 216.3).
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 for categorical
exclusion from further NEPA review.
Summary of Request
On August 1, 2025, NMFS received a request from TMC for an IHA
authorizing the take by Level B harassment of six species of marine
mammals and, additionally, take by Level A harassment of five of those
species, incidental to the Aak'w Landing Development Project. Following
NMFS' review of the application, TMC submitted a revised application on
December 23, 2025, and February 19, 2026. NMFS deemed the application
adequate and complete on March 9, 2026.
The specified activities include pile removal, vibratory and impact
pile driving, down-the-hole (DTH) drilling, and DTH anchoring. These
activities have the potential to result in Level A harassment and Level
B harassment of six species of marine mammals. Serious injury or
mortality is neither anticipated nor proposed to be authorized;
therefore, an IHA is appropriate. The IHA would be valid for the
statutory maximum of 1 year from the date of effectiveness and would
become effective upon written notification from TMC to NMFS, but not
beginning later than 1 year from the date of issuance or extending
beyond 2 years from the date of issuance.
Description of Proposed Activity
Overview
The proposed Aak'w Landing Development Project is part of a larger
effort developing dining, retail, and event spaces, as well as an
indigenous knowledge, science, and cultural learning center. The
purpose of the project is to construct a cruise ship dock and seawalk
adjacent to downtown Juneau. TMC would remove the existing Standard Oil
Pier and construct a dock and seawalk as well as restraint and mooring
dolphins. TMC would utilize impact and vibratory pile driving, DTH
drilling, and DTH anchoring to complete the planned work which may
result in marine mammal harassment.
Dates and Duration
The IHA would be effective upon written notification from TMC 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 currently scheduled to begin September 1, 2026, and
would occur on approximately 226 days (potentially non-consecutive).
However, project delays may occur due to several factors, including
project funding, permitting requirements, equipment and/or material
availability, weather-related delays, equipment maintenance and/or
repair, and other contingencies. Pile removal and installation would
occur during daylight hours only, which ranges from 8 to 18 hours per
day depending upon the season. No in-water work will occur from April
15 to June 1 to protect out-migrating salmon smolt.
Specific Geographic Region
The project is located adjacent to downtown Juneau on the eastern
shore of Gastineau Channel. Comprising part of Southeast Alaska's
Inside Passage, Gastineau Channel is a U-shaped, glacier-carved, fjord
and narrow channel that, at its approximate midpoint, runs between
Juneau (on mainland Alaska) and Douglas Island. The channel is
approximately 16 miles (25.7 km) long and its width varies between
4,000 to 6,000 feet (ft) (1219 to 1829 m). The southern end of
Gastineau Channel meets Stephens Passage, and the northern, shallower
end opens into Auke Bay and Lynn Canal. Gastineau Channel experiences
tidal ranges of 16.3 ft (4.9 m) (NOAA, 2025). There are 12 documented
anadromous fish streams in the vicinity of the project (Alaska
Department of Fish and Game [ADF&G] 2025a); each supporting at least
one species of Pacific salmon.
The Juneau waterfront is heavily influenced by industrialization,
characterized by a blend of heavy marine industrial activities and
significant tourism infrastructure. The waterfront supports commercial
seafood processing, fishing, and, historically, major mining
operations. Marine mammals within the area are consistently subjected
to commercial and recreational vessel traffic, most notably large
cruise ships.
[[Page 20112]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.005
Detailed Description of the Specified Activity
TMC is proposing to construct a new dock, seawalk, and associated
infrastructure in Juneau, Alaska. The new dock would accommodate a
class of increasingly larger cruise ships, provide additional safe
harbor in Juneau, and reduce marine traffic congestion in Gastineau
Channel by allowing docked ships to spread out across the waterfront
and eliminating ship-to-shore boat trips. More details on the purpose
and need of the project can be found in section 1.2.2 of TMC's
application.
To complete the project, TMC would remove the existing Standard Oil
Pier, install and remove temporary template piles, and install
permanent piles using a vibratory hammer, impact hammer, and drilled
shaft (table 1) to construct a dock, seawalk, vehicle trestle,
pedestrian walking trestle, mooring trestle, restraint dolphins, and
mooring dolphins. In total, up to 160 existing wood piles would be
removed, up to 160 temporary template piles would be installed and
subsequently removed, and 268 permanent piles would be installed. Below
we provide a summary of the planned work; please see sections 1.2.3 and
1.2.4 of TMC's application for more details.
Removal of Standard Oil Pier
The existing Standard Oil Pier, comprised of 281 20-in wood piles,
would be removed using a dead pull method via a crane or, if this is
not feasible, by vibrating out the piles using a vibratory hammer. TMC
expects that it will take approximately 5 minutes to remove each pile
and up to 20 piles per day could be removed resulting in approximately
15 days of work. Because the dead-pull method would not generate in-
water noise, only use of the vibratory hammer has the potential to
result in take, by Level B harassment, of marine mammals. Level A
harassment from pile removal is not anticipated or proposed to be
authorized. For purposes of their application, TMC conservatively
assumes all piles would need to be removed using a vibratory hammer;
however, this is unlikely.
Permanent Pile Installation
Permanent piles would be installed to construct the dock (n=66),
seawalk (n=78), and restraint and mooring dolphins (n=16 and 12,
respectively). In addition, to construct the vehicle trestle and
pedestrian walkway, 68 piles would be installed and, to construct the
mooring trestle, 28 piles would be installed. All permanent piles will
be installed by vibrating and impact hammering and, where they are
installed below -60 ft, DTH drilling to break up the bedrock layer.
Additionally, all the 42-in piles and 28 of the 48-in piles would have
tension anchors installed using DTH anchoring methods (referred to
hereafter as DTH anchoring). First, piles would be vibrated into place.
Each piling would then be driven to tip elevation using an impact
hammer to seat the piling into the bedrock. Once the 42- and 48-inch
piles achieve tip elevation, a DTH hammer would be placed inside the
[[Page 20113]]
piling to install tension anchors. Piles would be installed to a depth
to be determined by geotechnical investigation. The pile would then be
anchored with concrete.
Temporary Pile Installation and Removal
Pile templates would be constructed by installing temporary pilings
to be used as a guide for positioning permanent pilings. Not all
permanent piles will require temporary piles to aid in their
installation; however, the exact number of temporary piles necessary to
support the permanent piles is currently unknown. TMC will assess the
need for temporary piles during construction; however, for purposes of
their application, they assume no more than 160 temporary piles will be
required.
Piles installed below -60 ft would also require DTH drilling given
the bedrock layer is shallow, and therefore vibratory and impact
driving alone is insufficient to drive the piles to their needed depth.
Unlike permanent piles, the piles would not be anchored using a DTH
drilling method as they are temporary. In their application, TMC
assumes all 160 piles require DTH drilling. Temporary piles would be
extracted using the vibratory hammer. Details regarding pile
installation and removal specifications are provided in table 1.
BILLING CODE 3510-22-P
[[Page 20114]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.006
Proposed mitigation, monitoring, and reporting measures are
described in detail later in this document (please see Proposed
Mitigation and Proposed Monitoring and Reporting).
[[Page 20115]]
Description of Marine Mammals in the Area of Specified Activities
Sections 3 and 4 of TMC's application summarize available
information regarding the status and trends, distribution and habitat
preferences, and behavior and life history of the potentially affected
species. NMFS fully considered all this information, and we refer the
reader to these descriptions in the application instead of reprinting
the information. Additional information on 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 2 lists all the species or stocks for which take may occur
and is proposed to be authorized and summarizes information related to
the population or stock, including regulatory status under the MMPA and
Endangered Species Act (ESA), as well as the potential biological
removal (PBR), where known. The MMPA defines PBR as the maximum number
of animals, not including natural mortalities, which 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, the 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 geographical area, if known, that
comprises that stock. For some species, this area may extend beyond
U.S. waters. All managed stocks in this region are assessed in NMFS'
U.S. Alaska SARs (Carretta et al., 2025). All values presented in table
2 are the most recent available at the time of publication, including
from the draft 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>.
[[Page 20116]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.007
[[Page 20117]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.008
BILLING CODE 3510-22-C
As indicated above, table 2 lists the 6 species (10 total stocks)
that temporally and spatially co-occur with the specified activities to
the degree that incidental take could potentially occur. TMC's
application provides general information on each species and stock
provided in table 2 as well as more site-refined information as it
relates to the analysis, including information on biologically
important areas (BIAs) near the project area. In summary, the
occurrence of marine mammals in the project area is species specific
with some species (e.g., Dall's porpoise, killer whales) occasionally
present while others exhibit more frequent occurrence (e.g.,
pinnipeds). Marine mammals utilize the project area primarily for
foraging and transiting. The northern portion of the Frederick Sound
and Stephens Passage humpback whale foraging BIA, which is active June
through October, overlaps with the ensonified areas for all DTH
drilling activities and vibratory pile driving of 48-in piles. NMFS
incorporates this information by reference and therefore does not
repeat it here. Please see section 4 in TMC's application for more
detailed information on each species.
Marine Mammal Hearing
Hearing is the most vital sensory modality for marine mammals
underwater, and exposure to anthropogenic sound can have deleterious
effects. To appropriately assess the potential effects of sound
exposure, it is necessary to understand the frequency ranges that
marine mammals can hear. Not all marine mammal species have equal
hearing capabilities or hear over the same frequency range (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.). Subsequently, NMFS (2018, 2024) described generalized
hearing ranges for these marine mammal hearing groups. Generalized
hearing ranges were chosen based on the approximately 65-decibel (dB)
threshold from the normalized composite audiograms, except for lower
limits for low-frequency cetaceans, where the lower bound was deemed to
be biologically implausible, and the lower bound from Southall et al.
(2007) was retained. In October 2024, NMFS published its 2024 Updated
Technical Guidance, which includes updated thresholds and weighting
functions to inform auditory injury estimates and replaces the 2018
Technical Guidance referenced above. This 2024 Updated Technical
Guidance represents the best available science. Marine mammal hearing
groups and their associated hearing ranges are provided in table 3.
[[Page 20118]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.009
Potential Effects of Specified Activities on Marine Mammals and Their
Habitat
This section includes a discussion of how components of the Aak'w
Landing Development Project may affect marine mammals and their
habitat. The Estimated Take of Marine Mammals section later in this
document includes a quantitative analysis of the number of individuals
that are expected to be taken by the specified activities. The
Negligible Impact Analysis and Determination section considers the
content of this section, as well as the Estimated Take of Marine
Mammals section and the Proposed Mitigation section, to draw
conclusions regarding the likely impacts of both of the proposed
project 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.
There are a variety of types and degrees of effects on marine
mammals, prey species, and habitats that could result from the project.
Below is a brief description of the sound sources the projects would
generate, the general impacts of these activities, and an analysis of
the anticipated impacts on marine mammals from the projects, with
consideration of the proposed mitigation measures.
Description of Sound Sources
Impact hammers typically operate by repeatedly dropping and/or
pushing a heavy piston onto a pile to drive the pile into the
substrate. Sound generated by impact hammers is impulsive,
characterized by rapid rise times and high peak levels, a potentially
injurious combination (Hastings and Popper, 2005). Vibratory hammers
install piles by vibrating them and allowing the hammer's weight to
drive them into the substrate. Vibratory hammers typically produce less
sound (i.e., lower levels) than impact hammers. Peak SPLs may be 180 dB
or greater but are generally 10 to 20 dB lower than SPLs generated
during impact pile driving of the same-sized pile (Oestman et al.,
2009; California Department of Transportation (CALTRANS), 2015; 2020).
Sounds produced by vibratory hammers are non-impulsive; compared to
sounds produced by impact hammers, the rise time is slower, 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).
DTH systems use a combination of percussive and drilling
mechanisms, with the hammer acting directly on the rock to advance a
hole into the rock, and also advance the pile into that hole. The
hammer drills through the bedrock using a rotating function like a
normal drill, in concert with a hammering mechanism operated by a
pneumatic (or sometimes hydraulic) component integrated into the DTH
hammer to increase speed of progress through the substrate (i.e., it is
similar to a ``hammer drill'' hand tool). Therefore, DTH systems
include both impulsive and continuous components. For this project, TMC
would utilize DTH drilling and DTH anchoring methods to install 42- and
46-in piles.
Potential Effects of Underwater Sound on Marine Mammals
The introduction of anthropogenic noise into the aquatic
environment from vibratory pile removal, vibratory and impact pile
installation, and the DTH drilling and DTH anchoring are the means by
which marine mammals may be harassed from TMC's specified activities.
Anthropogenic sounds span a broad range of frequencies and sound levels
and can have highly variable impacts on marine life, from none or minor
to potentially severe responses, depending on received levels, duration
of exposure, behavioral context, and other factors. Broadly, underwater
sound from active acoustic sources, such as those in these projects,
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; 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 the use of impact/vibratory hammers is reasonably likely to result
in such effects (see below for further discussion).
Potential physiological effects from sound sources, particularly
impulsive sound, can range from behavioral disturbance or tactile
perception to physical discomfort, slight injury to the internal organs
and the auditory system,
[[Page 20119]]
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). However, the Project
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 can result in auditory threshold shifts and
behavioral responses (e.g., avoidance, temporary cessation of foraging
and vocalizing, changes in dive behavior). It can also lead to non-
observable physiological responses, such as increased stress hormone
levels. Additional noise in a marine mammal's habitat can mask acoustic
cues used in 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, would
occur almost exclusively for noise within an animal's hearing range. We
describe below the specific manifestations of acoustic effects that may
occur from the specified activities.
Richardson et al. (1995) described zones of increasing effect
intensity that might be expected to occur with distance from a source,
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 to the area
where the signal is audible to the animal and sufficiently intense to
elicit behavioral or physiological responsiveness. The third is a zone
within which, for high-intensity signals, the received level is
sufficient to cause discomfort or tissue damage to auditory or other
systems. Overlaying these zones to some extent is the area within which
masking (i.e., when a sound interferes with or masks an animal's
ability to detect a signal of interest above the absolute hearing
threshold) may occur; the masking zone may vary widely in size.
Hearing Threshold Shifts
NMFS defines a noise-induced threshold shift (TS) as a change,
usually an increase, in the audibility threshold at a specified
frequency or portion of an individual's hearing range above a
previously established reference level (NMFS, 2018, 2024). The amount
of threshold shift 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), the likelihood an individual would be
exposed for a long enough duration or to a high enough level to induce
a TS, the magnitude of the TS, the 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 the 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).
Temporary Threshold Shift
A temporary threshold shift (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 auditory injury
(AUD INJ). Based on data from marine mammal TTS measurements (see
Southall et al., 2007, 2019), a TTS of 6 dB is considered the minimum
threshold shift clearly larger than any day-to-day or session-to-
session variation in a subject's normal hearing ability (Finneran et
al., 2000, 2002; Schlundt et al., 2000). As described in Finneran
(2015), marine mammal studies have shown that the amount of TTS
increases with the 24-hour cumulative sound exposure level (SEL24) in
an accelerating fashion: at low exposures with lower SEL24, the amount
of TTS is typically small, and the growth curves have shallow slopes.
At higher SEL<INF>24</INF> exposures, the growth curves become steeper
and approach a linear relationship 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 more impactful (similar to those discussed in
auditory masking, below). For example, a marine mammal may readily
compensate for a brief, relatively small amount of TTS in a non-
critical frequency range that occurs while the animal is traveling
through the open ocean, where ambient noise is lower and competing
sounds are fewer. Alternatively, a larger amount and longer duration of
TTS sustained during times when communication is critical for
successful mother/calf interactions could have more severe impacts. We
note that reduced hearing sensitivity, as a simple function of aging,
has been observed in marine mammals, as well as in humans and other
taxa (Southall et al., 2007), suggesting that strategies exist to cope
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 (Kryter, 2013). While experiencing TTS, the hearing
threshold rises, so the sound must be louder to be heard. In
terrestrial and marine mammals, TTS can last from minutes to hours (in
cases of strong TTS) (Finneran, 2015). 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, and Yangtze finless porpoise (Neophocoena
asiaeorientalis) (Southall et al., 2019). For pinnipeds in water,
measurements of TTS are limited to harbor seals, northern elephant
seals, bearded seals (Erignathus barbatus), and California sea lions
(Kastak et al., 1999, 2007; Kastelein et al., 2019b, 2019c, 2021,
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
[[Page 20120]]
matching previous predictions of TTS onset (Reichmuth et al., 2016).
These studies examine hearing thresholds in marine mammals before and
after exposure to intense or long-duration sound. The difference
between the pre-exposure and post-exposure thresholds can be used to
determine the amount of threshold shift at various post-exposure times.
The amount and onset of TTS depend 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
would be lower than that 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 warning sound
preceded a relatively loud 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 enable conditioned hearing
reduction and filtering of low-frequency ambient noise, including
increased stiffness and control of middle ear structures, as well as
placement of inner ear structures (Ketten et al., 2021). Data available
on 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, and there are no measured PTS data for cetaceans,
but such relationships are assumed to be similar to those in humans and
other terrestrial mammals. PTS typically occurs at exposure levels at
least several dB above that inducing mild TTS (e.g., a 40-dB threshold
shift approximates PTS onset (Kryter et al., 1966; Miller, 1974), while
a 6-dB threshold shift approximates TTS onset (Southall et al., 2007,
2019). Based on data from terrestrial mammals, a precautionary
assumption is that the AUD INJ 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
AUD INJ cumulative sound exposure level thresholds are 15 to 20 dB
higher than TTS cumulative 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 AUD INJ could occur.
Auditory Injury and Permanent Threshold Shift
NMFS (2024) defines AUD INJ as damage to the inner ear that can
result in tissue destruction, such as 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 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 generally
affects only a limited frequency range, and animals with PTS have 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 threshold shift approximates the onset of
PTS (see Ward et al., 1958, 1959; Ward, 1960; Kryter et al., 1966;
Miller, 1974; Ahroon et al., 1996; Henderson et al., 2008). However, a
variety of terrestrial and marine mammal studies (see Ward et al.,
1958; Ward et al., 1959; Ward, 1960; Miller et al., 1963; Kryter et
al., 1966; Finneran et al., 2007; Kastelein et al., 2013) indicate that
threshold shifts of up to 40 to 50 dB (measured a few minutes after
exposure) may be induced without resulting in PTS. PTS levels for
marine mammals are estimates; with the exception of a single study
unintentionally inducing PTS in a harbor seal (Kastak et al., 2008), no
empirical data measure PTS 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). NMFS has set the PTS onset as an initial
threshold shift of 40 dB.
However, after sound exposure ceases or between successive sound
exposures, the potential for recovery from hearing loss exists. Thus,
because a threshold shift is measured a few minutes after noise
exposure does not mean that those initial shifts are persistent (i.e.,
no recovery). When initial threshold shifts fully recover back to
baseline hearing levels, these are considered TTS. PTS indicates there
is no full recovery back to baseline hearing levels; however, it does
not mean there is no recovery. Rather, PTS indicates incomplete
recovery of hearing. Recovery depends on the initial threshold shift
amount, the frequency at which the shift occurred, the temporal pattern
of exposure (e.g., exposure duration; continuous vs. intermittent
exposure), and the physiological mechanisms underlying the shift (e.g.,
mechanical vs. metabolic). Since recovery is complicated, our current
AUD INJ onset criteria do not account for the potential for recovery.
Behavioral Effects
Exposure to noise can also 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 a behavioral disturbance,
and for responses that do, those of higher level or longer duration
have the potential to affect foraging, reproduction, or survival.
Behavioral disturbance may include subtle changes (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
[[Page 20121]]
response or aggressive behavior (such as tail/fin slapping or jaw
clapping); and avoiding 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., 2004). Animals are most likely to habituate to
predictable, unvarying sounds. 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, in which
an unpleasant experience leads to subsequent responses, often in the
form of avoidance, at lower levels of exposure.
As noted above, behavioral state may affect the type of response.
For example, resting animals 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., 2004; 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; Finneran et al., 2003). 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
sound; 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 briefly reacts
to an underwater sound by changing its behavior or moving a small
distance, the resulting change is 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 on 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., 2016).
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 in dive behavior
resulting from acoustic exposure depends on what the animal is doing at
the time of exposure and on the type and magnitude of the response.
Disruption of feeding behavior can be difficult to correlate with
anthropogenic sound exposure, so it is usually inferred by observed
displacement from known foraging areas, the appearance of secondary
indicators (e.g., bubble nets or sediment plumes), or changes in dive
behavior. As for other types of behavioral response, the frequency,
duration, and temporal pattern of signal presentation, as well as
differences in species sensitivity, are likely contributing factors to
differences in response in any given circumstance (e.g., Croll et al.,
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al.,
2007). A determination of whether foraging disruptions incur fitness
consequences would require information on, or estimates of, the
energetic requirements of the affected individuals, the relationship
between prey availability, foraging effort, and success, and the
animal's life history stage.
Respiration rates vary naturally with different behaviors, and
alterations in 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 of
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 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 due to 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). 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 the abundance or distribution patterns of the
affected species in the affected region if habituation to 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, with
directed, rapid movement away from the perceived location of a sound
source. The flight response differs from other avoidance responses in
its intensity (e.g., directed movement and travel rate). Relatively
little information exists on the flight responses of marine mammals to
anthropogenic signals, although observations of flight
[[Page 20122]]
responses to the presence of predators have been made (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 affect marine mammals in more
subtle ways. Increased vigilance may incur costs from the diversion of
attention (i.e., when a response requires heightened vigilance, it may
come at the expense of reduced attention to other critical behaviors,
such as foraging or resting). These effects have generally not been
demonstrated in marine mammals, but studies of 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 reductions in fitness (e.g., declines in
body condition) and subsequent reductions 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 result in sleep deprivation or stress.
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, is more likely to be significant if it lasts more than one
diel cycle or recurs 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
multiple days does not necessarily mean that individual animals are
exposed to activity-related stressors for multiple days, or, further,
exposed in a manner that results in sustained, multi-day, substantive
behavioral responses.
Physiological Stress Responses
An animal's perception of a threat may be sufficient to trigger
stress responses that include some combination of behavioral, autonomic
nervous system, neuroendocrine, and immune responses (e.g., Selye,
1950; Moberg, 2000). In many cases, an animal's first and sometimes
most economical response (in terms of energetic costs) 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 pituitary hormone secretion have been implicated in
reproductive failure, altered metabolism, reduced immune competence,
and behavioral disturbances (e.g., Moberg, 1987; Blecha, 2000).
Increases in glucocorticoid levels are also associated with stress
(Romano et al., 2004).
The primary distinction between stress (which is adaptive and does
not normally place an animal at risk) and ``distress'' is the cost of
the response. During a stress response, an animal uses its glycogen
stores, which 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 energy
reserves to a sufficient level 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 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. 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 some of these responses may be classified as ``distress.'' In
addition, any animal experiencing TTS would likely also experience
stress responses (NRC, 2005); however, distress is unlikely to result
from these projects based on observations of marine mammals during
previous, similar construction projects in southeast Alaska.
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 specific frequencies for marine
mammals that rely on 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).
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 the
detection of mysticete communication calls and other potentially
important natural sounds
[[Page 20123]]
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. Few studies have addressed 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 use and is
more likely to occur in the presence of broadband, relatively
continuous noise sources such as vibratory pile removal or
installation. The energy distribution of pile-driving sound spans a
broad frequency spectrum and is expected to fall within the audible
range of marine mammals present in the project areas. 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 the 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 noise band, thereby reducing the communication space of
animals (e.g., Clark et al., 2009) and increasing 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
signals, and at higher levels and for longer durations could have long-
term chronic effects on marine mammal species and populations. However,
the noise generated by the TMC's proposed activities would occur only
intermittently across 226 days in a relatively small area focused
around the proposed construction sites. Thus, while the TMC's proposed
activities may mask some acoustic signals 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 affected.
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 across any of these modes and may result from a need to
compete with increased background noise, or may reflect increased
vigilance or a startle response. For example, in the presence of
potentially masking signals, humpback whales and killer whales have
been observed to increase the length of their songs (Miller et al.,
2000; Fristrup et al., 2003) or vocalizations (Foote et al., 2004),
respectively, while North Atlantic right whales (Eubalaena glacialis)
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 physalus)
have also been documented to lower the bandwidth, peak frequency, and
center frequency of their vocalizations in the presence of increased
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 that exposed
them to vessel noise, have been observed to increase their vocalization
rate and produce louder signals during periods of increased outboard
engine noise (Dahlheim and Castellote, 2016). Alternatively, in some
cases, animals may cease sound production during the production of
aversive signals (Bowles et al., 1994; Wisniewska et al., 2018).
Under certain circumstances, marine mammals that experience
significant masking could also be impaired in maximizing their
performance fitness for survival and reproduction. Therefore, when the
coincident (masking) sound is human-made, it may be considered
harassment if it disrupts or alters 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 associated with
harassment). Therefore, under certain circumstances, marine mammals
whose acoustic sensors or environment are severely masked could also be
impaired in maximizing their performance fitness for survival and
reproduction.
Airborne Acoustic Effects
Pinnipeds occurring near the project site could be exposed to
airborne sounds associated with construction activities, depending on
their distance from these activities, which could cause behavioral
harassment. Airborne noise would primarily be an issue for pinnipeds
that are swimming or hauled out near either project site, within the
range of noise levels elevated above the airborne acoustic harassment
criteria. Cetaceans are not expected to be exposed to airborne sounds
that would result in harassment as defined under the MMPA.
We recognize that pinnipeds in the water may be exposed to airborne
sound that could result in behavioral harassment when they lift their
heads above the water or when they haul out. Most likely, airborne
sound would cause behavioral responses similar to those discussed above
in relation to underwater sound. For instance, anthropogenic sound
could cause hauled-out pinnipeds to exhibit changes in their normal
behavior, such as a reduction in vocalizations, or to flush from
haulouts, temporarily abandon the area, and/or move further from the
source. However, these animals previously would have been ``taken''
because of exposure to underwater sound above the behavioral harassment
thresholds, which are, in all cases, larger than those associated with
airborne sound. Thus, the behavioral harassment of these animals is
already accounted for in these estimates of potential take. Therefore,
authorization of additional incidental take resulting from airborne
sound for pinnipeds was not requested by TMC and NMFS has
[[Page 20124]]
determined is not warranted; airborne sound is not discussed further
here.
Potential Effects on Marine Mammal Habitat
TMC's specified activities could have localized, temporary impacts
on marine mammal habitat, including prey, due to increased in-water
noise levels and water quality degradation. Increased noise levels may
affect the 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 areas where both
fishes and mammals occur and could affect foraging success.
Additionally, marine mammals may avoid the area during the proposed
construction activities; however, any displacement due to noise is
expected to be temporary and not to result in long-term effects on
individuals or populations.
The total area impacted by TMC's proposed activities is relatively
small compared to the available habitat within southeast Alaska. While
marine mammals may forage in Gastineau Channel near the project area,
the waters ensonified do not contain unique or particularly important
habitat relative to other waters in southeast Alaska. Moreover, the
Juneau waterfront area where the project would occur is industrialized.
Avoidance by potential prey (i.e., fish) of the immediate areas due
to increased noise is possible. The duration of fish and marine mammal
avoidance of this area after construction stops is unknown, but a rapid
return to normal recruitment, distribution, and behavior is
anticipated. Any behavioral avoidance by fish or marine mammals of
either disturbed area would still leave significantly large areas of
fish and marine mammal foraging habitat in the nearby vicinity.
The proposed project would occur within the same footprint as
existing marine infrastructure. The nearshore and intertidal habitats
where the proposed projects would occur are in industrialized areas
with relatively high marine vessel traffic. Temporary, intermittent,
and short-term habitat alteration may result from increased noise
levels during the proposed construction activities. Effects on marine
mammal habitat would be limited to temporary displacement from pile
removal and installation noise, and effects on prey species would be
similarly limited in time and space.
Water Quality
Temporary and localized reduction in water quality would occur as a
result of in-water construction activities. Most of this effect would
occur during the removal and installation of piles, when bottom
sediments are disturbed, and may temporarily increase suspended
sediment in the project area. During pile extraction, sediment attached
to the pile moves vertically through the water column causing a
sediment plume. However, since currents are so strong in the area,
following the completion of sediment-disturbing activities, suspended
sediment in the water column should dissipate and quickly return to
background levels across all construction scenarios.
Turbidity in the water column can reduce dissolved oxygen levels
and irritate the gills of prey fish in the proposed project areas.
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). However, turbidity plumes associated with the projects
would be temporary and localized, and fish in the proposed project
areas would be able to move away from and avoid the areas where plumes
may occur.
Overall, the water quality in the immediate area that is likely
impacted by the proposed construction activities for both projects is
relatively small compared to the available marine mammal habitat within
and surrounding Juneau. Therefore, it is expected that water quality
impacts on prey fish species due to turbidity, and therefore on marine
mammals, would be minimal and temporary.
Potential Effects on Prey
Sound may affect marine mammals by altering 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, it is not well documented.
Studies regarding the effects of noise on known marine mammal prey are
described here.
Fishes use 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 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 on fishes may include behavioral responses,
hearing damage, barotrauma (pressure-related injuries), and mortality.
Fish react to 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 their physiological state, 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 is likely restored when damaged cells are
replaced with new cells. Halvorsen et al. (2012b) showed that a TTS of
4-6 dB was recoverable within 24 hours in one species. Impacts would be
most severe when the individual fish is near the source, and the
exposure duration is long. Injury caused by barotrauma can range from
slight to severe and cause death; risk of injury is higher 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 prey
for marine mammals could be temporarily affected by noise from pile
removal and
[[Page 20125]]
installation. 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 in response to strong and/or intermittent sounds
that could harm fish. 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 indirectly affect
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 sound levels from pile driving, seismic activity,
or other human-made sources 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 from the specified activities, due
in part to their large reproductive capacity and naturally high levels
of predation and mortality. Any mortalities or impacts that might occur
would be negligible.
The greatest potential impact on marine mammal prey during
construction would occur during impact pile driving. Vibratory pile
removal/installation may elicit behavioral responses in fishes, such as
temporary avoidance of the area, but is unlikely to cause injuries to
fishes or have persistent effects on local fish populations. In-water
construction activities would only occur during daylight hours,
allowing fish to forage and transit the project area in the evening.
Construction would also have minimal permanent and temporary impacts on
benthic invertebrate species, a marine mammal prey source.
Potential Effects on Foraging Habitat
The proposed projects are 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
removal and installation of in-water piles would be temporary and
intermittent. The areas affected by these projects are relatively small
compared to the available habitat just outside the project areas, and
neither project would affect any areas of particular importance. Any
behavioral avoidance by fish in the disturbed areas 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 TMC's activities 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, the impacts of
the projects are not likely to adversely affect marine mammal foraging
habitat in the proposed project areas.
In summary, given the relatively small areas being affected, as
well as the temporary and mostly transitory nature of the proposed
construction activities, any adverse effects from TMC's activities on
prey habitat or prey populations are expected to be minor and
temporary. The most likely impact on fishes at the project sites would
be temporary avoidance of the area. Any behavioral avoidance by fish in
the disturbed areas would still leave significantly large areas of fish
and marine mammal foraging habitat in the nearby vicinity. Thus, we
conclude that the 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 on 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 which, in part, informs NMFS' consideration
of ``small numbers,'' the negligible impact determination, and effects
on the availability of marine mammals for subsistence use.
Harassment is the only type of take expected to result from these
activities. Except for 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 disrupting behavioral patterns, including, but not limited
to, migration, breathing, nursing, breeding, feeding, or sheltering
(Level B harassment).
Authorized takes would predominantly be by Level B harassment, as
using acoustic sources (i.e., vibratory and impact pile driving) can
potentially disrupt behavioral patterns for individual marine mammals.
There is also some potential for AUD INJ (Level A harassment) to result
for four species of marine mammals. The proposed mitigation and
monitoring measures for both projects are expected to minimize the
amount and severity of the taking to the extent practicable.
As previously described, no serious injury or mortality is
anticipated or proposed to be authorized for either proposed 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 the best
available science indicates that 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 would 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. While these factors are incorporated into 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 reasonably expect to be behaviorally harassed (equated to Level B
harassment) or incur AUD INJ of some degree (equated to Level A
harassment). Below, we describe the thresholds used by TMC and NMFS for
this analysis.
Level B Harassment
Though significantly driven by the received level, the onset of
behavioral disturbance from anthropogenic noise exposure is also
informed to varying degrees by other factors. These factors are related
to the source or exposure
[[Page 20126]]
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; Ellison et al., 2012). Based on available
science and the practical need to use a threshold based on a
predictable, measurable metric for most activities, NMFS typically uses
a generalized acoustic threshold based on the 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 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. Level B harassment estimates based on these
behavioral harassment thresholds potentially include TTS, as, in most
cases, TTS likely occurs at distances from the source less than those
at which behavioral harassment may occur. TTS of sufficient degree can
manifest as behavioral harassment and reduced hearing sensitivity, and
the potential reduction in opportunities to detect important signals
(conspecific communication, predators, prey) may result in behavior
patterns that would not otherwise occur.
TMC's proposed activities include continuous (vibratory pile
driving, DTH drilling and DTH anchoring) and intermittent (impact pile
driving, DTH drilling, DTH anchoring) sources. Therefore, the Level B
harassment thresholds of 120 dB 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) (NMFS, 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). It includes updated thresholds
and updated weighting functions for each hearing group, provided in
table 4 below. The references, analysis, and methodology used to
develop the criteria are described in NMFS' 2024 Updated Technical
Guidance, available 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>.
BILLING CODE 3510-22-C
[[Page 20127]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.010
BILLING CODE 3510-22-P
Ensonified Area
Here, we describe the operational and environmental parameters of
the activity used to estimate the area ensonified above the acoustic
thresholds, including source levels and the transmission loss
coefficient.
Source levels applied to this project were derived from acoustic
data collected during installation of identical or similar sized piles
in Alaska and the U.S. west coast (table 5).
[[Page 20128]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.011
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, bottom composition, and
topography. The general formula for underwater TL is:
TL = B * Log<INF>10</INF> (R<INF>1</INF>/R<INF>2</INF>),
Where:
TL = transmission loss in dB
B = transmission loss coefficient; for practical spreading equals 15
R<INF>1</INF> = the distance of the modeled SPL from the driven
pile, and
R<INF>2</INF> = 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 coastal waters, such as those found in the Aak'w
Landing project area. In these environments, sound waves repeatedly
reflect off the surface and bottom, reflecting an expected propagation
environment between spherical and cylindrical spreading-loss
conditions. Therefore, the default coefficient of 15 is used to
calculate distances to the Level A harassment and Level B harassment
isopleths.
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), TMC calculated
distances to the Level A harassment and Level B harassment isopleths
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 and animal movement, NMFS developed an optional User
Spreadsheet tool to assist applicants in assessing the potential for
Level A harassment without the need for complex modeling (<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. The resulting isopleth does not account for animal
movement and represents the distance at which an individual would have
to remain for the entire duration of pile driving or DTH within a day.
As the amount of time considered in the calculation becomes longer, the
likelihood of an individual accumulating noise energy above threshold
at that distance becomes less realistic. However, individuals may
approach a source more closely than the calculated distance in which
case the amount of time needed to elicit the onset of AUD INJ
decreases. While the risk of AUD INJ is low overall due to expected
avoidance behavior, the User Spreadsheet offers a practical alternative
for estimating isopleth distances when more sophisticated modeling
methods are unavailable or are impractical.
Using the practical spreading model and assumptions identified in
tables 1 and 5, TMC calculated, and NMFS has carried forward into this
analysis, the distances to the Level A harassment and Level B
harassment thresholds for marine mammals (table 6).
BILLING CODE 3510-22-P
[[Page 20129]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.012
BILLING CODE 3510-22-C
Marine Mammal Occurrence
In this section, we provide information on the anticipated
occurrence of marine mammals present in the project area that informs
the take calculations in the following section (see Take Estimation and
table 8).
Density estimates are not readily available for the project area;
therefore, TMC reviewed scientific literature and marine mammal
occurrence data collected previously by IHA holders conducting
monitoring in the same area. They also consulted local Juneau marine
mammal subject matter experts to estimate the occurrence of marine
mammals that may be taken incidental to the specified activities (table
7). More information regarding literature and
[[Page 20130]]
sources cited can be found in section 6.1 of TMC's application.
Further, NMFS consulted information available for past projects
conducted at the Juneau waterfront and determined the TMC's proposed
occurrence rate of harbor seals is likely an underestimate and
modified, in coordination with TMC, the harbor seal occurrence rate for
this proposed IHA. In their application, TMC assumed 4 harbor seals per
day may be within the ensonified area based on data from Auke Bay which
is located to the northwest of the project area. However, in 2019, NMFS
received a request for an IHA modification that contained harbor seal
monitoring data collected prior to the Downtown Waterfront Improvements
Project, Juneau; the data indicated an average of 26 seals/day were
observed between November 4 and 14, 2019 (<a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-juneau-waterfront-improvement-project-juneau-alaska">https://www.fisheries.noaa.gov/action/incidental-take-authorization-juneau-waterfront-improvement-project-juneau-alaska</a>). Because the 2019 data
were collected essentially at the same location as the Aak'w Landing
location, NMFS has applied those data to the take estimates. TMC agreed
this approach was appropriate to ensure MMPA compliance (i.e., enough
take is authorized) during the project.
[GRAPHIC] [TIFF OMITTED] TN15AP26.013
Take Estimation
In this section, we describe how the project scope, ensonified
area, and species occurrence information provided above are used to
produce a quantitative estimate of the take that could occur and is
proposed for authorization.
As described above, density is not available in the project area;
therefore, TMC applied a simplistic approach which assumed that all
animals potentially within the project area on any given day may be
taken by harassment. Overall, the resulting formula for determining the
number of takes that may occur incidental to the project is:
Total take by harassment = occurrence estimate (in days) x pile
activity days
For species where a number of individuals per month was estimated
based on the best available science, TMC used the same approach;
however, to compensate for the monthly estimate, they applied a 30-day
correction factor to convert the number of animals observed per month
into a daily sighting rate (e.g., 30 harbor seals per month equates to
1 harbor seal per day).
For vibratory pile driving, it is unlikely that Level A harassment
would occur; therefore, all takes calculated incidental to this
activity were attributed to Level B harassment. Moreover, for killer
whales and harbor porpoise, Level A harassment incidental to impact
pile driving and DTH activities is also unlikely. The calculated
distance to Level A harassment thresholds for killer whales is
relatively short (see table 6) and represents extended durations.
Because an animal is unlikely to remain in such close proximity to the
piles for that time, AUD INJ is unlikely to occur. Further, killer
whales are a highly visible species such that PSOs are likely to detect
them and implement mitigation to avoid Level A harassment. The best
available science demonstrates that harbor porpoises are behaviorally
sensitive species and exhibit strong reactions to impulsive noise such
as impact pile driving. For example, displacement of harbor porpoises
has been observed during impact pile driving associated with the
construction at multiple offshore wind projects (Tougaard et al., 2009;
Bailey et al., 2010; D[auml]hne et al., 2013; Lucke et al., 2012;
Haelters et al., 2015; Brandt et al., 2018). These studies document
long-distance (i.e., several kilometers) displacement; however, the
duration of displacement has been documented to generally be temporary.
The piles involved in coastal construction projects are smaller than
those in these studies; however, other data support predicted avoidance
responses wherein porpoise move away from a man-made sound source;
thereby reducing accumulated noise energy. For example, Kok et al.
(2018) found that two captive harbor porpoises spatially avoided a
noisy pool when exposed to intermittent or continuous sound stimuli. In
summary, harbor porpoises are likely to avoid coastal construction-
related sound sources associated with the project to the degree that
AUD INJ is unlikely. For these reasons, NMFS is not proposing to
authorize Level A harassment for killer whales and harbor porpoise.
For those species where Level A harassment is expected to occur,
TMC assumed that all animals present within the project area on days
when activities with the potential for Level A harassment occurs (i.e.,
impact hammering and DTH activities; 144 days) could incur Level A
harassment. The remaining takes, based on the total amount of take
calculated, are predicted to result in Level B harassment only.
To understand the potential for the total number of takes
incidental to impact pile driving and DTH activities to be by Level A
harassment for
[[Page 20131]]
humpback whales, harbor seals, and Steller sea lions, TMC considered
the number of days these activities may occur (n = 144) and calculated
take using this value:
Level A harassment = occurrence estimate (in days) x 144 days
To estimate the number of takes by Level B harassment incidental to
impact pile driving and DTH activities, TMC subtracted the number of
takes by Level A harassment from the total takes calculated via the
equation above. NMFS acknowledges that the number of estimated
exposures above higher threshold criteria using the methodology (e.g.,
sound exposures exceeding Level A harassment criteria), also
encompasses the potential for less impactful effects (e.g., Level B
harassment). An individual exposure exceeding a Level A harassment
criterion may not result in actual AUD INJ, yet the individual may have
experienced Level B harassment. This outcome is accounted for in our
authorization of potential higher-level takes and in our analysis.
Level B harassment = Total take by harassment-Level A harassment
For Steller sea lions, TMC also considered the presence of a nearby
haulout site. Circle Point, a minor haulout approximately 27.80 km to
the southeast of the project site, is within the DTH drilling and DTH
anchoring Level B harassment zones. A minor haulout is one that
supports fewer than 200 animals or is used irregularly. Given the
haulout is used intermittently, when used may support anywhere from 1
to 199 individuals, and is located relatively far from the project site
(although within the Level B harassment zone), TMC has added 199
exposures to the calculated total take estimate for this species. Given
the variability in haulout use, TMC determined, and NMFS agrees, that
assuming 199 animals would be exposed during every day that DTH
activities would occur would be a gross overestimate of take and that
the resulting number of takes using this method is reasonable. Methods
for attributing a proportion of those takes to Level A harassment
incidental to impact pile driving and DTH drilling and DTH anchoring
follows the methodology described above. Remaining takes are attributed
to Level B harassment.
Using the calculations described above, TMC has requested, and NMFS
proposes to authorize, the number of takes identified in table 8. The
proportion of the stock values presented in table 8 reflects the
assumption that each take is of a different individual and, where takes
may occur to any stock of a given species, that all takes proposed to
be authorized are attributed to each stock. For porpoise and killer
whales which tend to transit through the area, it is possible that
takes are of unique individuals. However, for species which demonstrate
some residency or persistence (humpback whales and pinnipeds), it is
likely that fewer number of individuals than the number of takes
proposed to be authorized will be harassed repeatedly. Further, for
humpback whales, killer whales, and Steller sea lions, it is unlikely
that all takes authorized would occur to only one stock. For these
reasons, the proportion of stock values in table 8 are likely
overestimates for all species except porpoises.
[[Page 20132]]
[GRAPHIC] [TIFF OMITTED] TN15AP26.014
Proposed Mitigation
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 (ITA)
to include information about the availability and feasibility (economic
and technological) of equipment, methods, and the 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) How and to what degree the successful implementation of the
measure(s) is expected to reduce impacts on marine mammal species or
stocks and their habitat. This considers the nature of the potential
adverse impact being mitigated (its likelihood, scope, and range). It
further considers the likelihood that the measure would be effective if
implemented (probability of accomplishing the mitigating result if
implemented as planned), the likelihood of effective implementation
(probability of implementation as planned); and
(2) The practicability of the measures for applicant
implementation, which may consider such things as cost and impact on
operations.
The number and/or intensity of incidents of takes will be minimized
through the incorporation of the mitigation measures that were proposed
by TMC. TMC has agreed that all of the mitigation measures are
practicable and NMFS agrees that these measures are sufficient to
achieve the least practicable adverse impact on the affected marine
mammal species or stocks and their habitat and have included them in
the IHA as proposed mitigation requirements.
Establishment of Clearance and Shutdown Zones
TMC proposed, and NMFS would require, the establishment of
clearance and shutdown zones identified in table 10 for pile removal,
installation, DTH drilling, and DTH anchoring. The purpose of
``clearance'' of a particular zone is to prevent potential instances of
auditory injury and more severe behavioral disturbance the maximum
extent practicable by delaying the commencement of impact pile driving
if marine mammals are detected within certain pre-defined distances
from the pile being installed. The purpose of a shutdown is to prevent
a specific acute impact, such as auditory injury or severe behavioral
disturbance of sensitive species, by halting the activity.
Additionally, to avoid unauthorized takes, TMC would delay an activity
or shut down in the event that a species for
[[Page 20133]]
which take is not authorized or for which take has been reached is
observed within or entering any designated harassment zone. If pile
driving or DTH activities are 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 clearance and shutdown zones indicated in table 9 or 15 minutes
have passed without re-detection of the animal.
In-water construction activities that do not include the specified
activities but require heavy equipment will also shut down if a marine
mammal approaches within 10 m to avoid direct interaction.
In general, the clearance and shutdown zones represent the
calculated Level A harassment distance rounded up for ease of
implementation. However, a maximum shutdown zone of 2,000 m for low
frequency cetaceans and 300 m for very high frequency cetaceans and
pinnipeds will be maintained due to detectability and/or
practicability. In addition, NMFS is proposing a maximum 25m clearance
and shutdown zone be maintained for harbor seals. Data collected by the
City and Borough of Juneau in 2019 indicates that extended mitigation
zones would not be practicable as harbor seals are frequently observed
in close proximity (within 130 m) to the project site such that the
specified activities would not be able to commence or continue to the
degree that the project could be completed within reasonable time
frames. For the City and Borough of Juneau, harbor seal presence close
to the pile driving location resulted in a need for a modified IHA to
reduce original shutdown zone sizes (<a href="https://www.fisheries.noaa.gov/action/incidental-take-authorization-juneau-waterfront-improvement-project-juneau-alaska">https://www.fisheries.noaa.gov/action/incidental-take-authorization-juneau-waterfront-improvement-project-juneau-alaska</a>). NMFS has applied that experience to this Aak'w
Landing project. NMFS notes that TMC's application proposed a 300m
shutdown for harbor seals; however, TMC was unaware these data existed
during development of their application nor of the prior need for the
City and Borough of Juneau's modified IHA (85 FR 18562, April 2, 2020).
[GRAPHIC] [TIFF OMITTED] TN15AP26.015
Soft-Start
TMC would use soft-start procedures for impact pile driving to
provide additional protection to marine mammals by issuing a warning
and/or giving them a chance to leave the area before the hammer
operates at full capacity. 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.
This soft-start would be implemented at the start of each day's impact
pile driving and at any time following cessation of this activity for a
period of 30 minutes or longer within a day.
[[Page 20134]]
Bubble Curtains
TMC has not proposed to use a bubble curtain during pile
installation, due to economic and temporal impracticability. In
general, bubble curtains reduce noise levels near the source,
minimizing exposure levels. However, requiring use of a bubble curtain
would reduce the number of piles that could be installed in a day due
to the time it takes to install and move the device. Therefore, the
duration (months) over which the project would occur would be extended,
increasing project costs and exposing marine mammals to underwater
sound over longer time periods. For these reasons, TMC has determined,
and NMFS agrees, that use of a bubble curtain is not practicable.
Vessel Strike Avoidance
Implementation of the vessel strike avoidance measures proposed by
TMC is expected to reduce the risk of vessel strike to the degree that
vessel strike would be avoided. While the likelihood of a vessel strike
is generally low without these measures, vessel interaction is one of
the most common ways that marine mammals are seriously injured or
killed by human activities. TMC vessels will adhere to the Alaska
Humpback Whale Approach Regulations (50 CFR 216.18, 223.214, and
224.103(b)) when transiting to and from the project site and operate at
a slow, safe speed when near a humpback whale (33 CFR 83.06).
All specific proposed monitoring, and reporting requirements can be
found in a draft IHA for this action 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>.
Based on our evaluation of TMC's proposed mitigation 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, with particular focus on
rookeries, mating grounds, and similar areas of significance.
Proposed Monitoring and Reporting
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 to both
compliance and ensuring the most value is obtained from the required
monitoring.
Monitoring and reporting requirements prescribed by NMFS should
help improve the 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 TMC in its adequate and complete application
TMC has agreed to the requirements. NMFS describes these below as
requirements and has included them in the proposed.
TMC would abide by all monitoring and reporting measures contained
within the IHA, if issued, and their Protected Species Monitoring 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>).
At least two PSOs will be on duty during pile driving and at least
three PSOs will be on-duty during DTH drilling and DTH anchoring. TMC
would also employ one PSO during times when non-pile related in-water
work is occurring. The locations of PSOs will be chosen based on site
accessibility and field of vision and are designed to monitor to the
maximum extent practicable. PSO locations include Harris Harbor
(Station 1), on the beach in front of the Juneau Seawalk (Station 2),
Coast Guard dock (Station 3), and Sheep Creek Beach and Fishing Area
(Station 4). PSO scenarios are summarized in table 10.
[GRAPHIC] [TIFF OMITTED] TN15AP26.016
Monitoring would take place from 30 minutes prior to initiation of
pile driving or removal and DTH activities through 30 minutes post-
completion of pile driving activity. Monitoring would be conducted
during periods of sufficient visibility for the lead PSO to determine
that the clearance and shutdown zones indicated in table 10 are clear
of marine mammals.
All PSOs must be NMFS-approved and have no other assigned tasks
during
[[Page 20135]]
monitoring periods. At least one PSO must have prior experience
performing the duties of a PSO during the specified activities. At
least two PSOs will be on duty during pile driving activities and at
least three PSOs will be on-duty during DTH drilling and DTH anchoring.
Where a team of three or more PSOs is required, a lead observer or
monitoring coordinator would be designated. The lead observer must have
prior experience working as a marine mammal observer during
construction. Additional PSOs may be employed during periods of low or
obstructed visibility to ensure the entirety of the shutdown zone is
monitored.
TMC would submit a draft report 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. TMC will provide a final report to NMFS within 30 days
following resolution of NMFS' comments on the draft report.
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. TMC would also be required to submit reports on any
observed injured or dead marine mammals. If the death or injury was
clearly caused by a specified activity, the TMC 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. TMC would
not resume its activities until notified by NMFS.
Specific proposed monitoring, and reporting requirements can be
found in the draft IHA 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 defines negligible impact as an effect of the specified
activity that cannot reasonably be 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 absence of likely adverse effects on
annual recruitment or survival rates (i.e., population-level effects).
An estimate of the number of takes alone is insufficient to support 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), effects on habitat, and the likely
effectiveness of the mitigation. We also assess the number, intensity,
and context of estimated takes by evaluating them against population
status. Consistent with the 1989 preamble to NMFS' implementing
regulations (54 FR 40338, September 29, 1989), impacts from other past
and ongoing anthropogenic activities are incorporated into this
analysis via their effects 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).
To avoid repetition, the following analysis applies to all species
listed in table 8 given that the anticipated effects of TMC's
activities on this different marine mammal stocks are expected to be
similar. There is little information on the nature or severity of the
impacts, or on the size, status, or structure of any of these species
or stocks, which would lead to a different analysis for this activity.
Specifically, the specified activities may result in take, in the
form of Level A harassment and/or Level B harassment, from underwater
sounds generated from pile driving and removal. Potential takes could
occur if individuals of these species are present in zones ensonified
above the thresholds for Level A harassment and/or Level B harassment
identified above when these activities are underway. TMC would
implement mitigation measures designed to reduce the potential for and
severity of harassment that effect the least practicable adverse impact
on the affected marine mammal species and stocks during the specified
activities. Given the nature of the proposed activities, NMFS does not
anticipate serious injury or mortality due to TMC's specified
activities, even in the absence of required mitigation.
For all species and stocks, take is expected to occur within a
limited, confined area (adjacent to the project site) of the species'
range, including Southeast Alaska. The intensity and duration of take
by Level A harassment and/or Level B harassment would be minimized
through the proposed mitigation measures described herein. Furthermore,
the number of takes proposed for authorization is small compared to the
relative stock's abundance, even assuming that every take for any
particular species could wholly occur to individuals of an individual
stock.
NMFS is proposing to authorize take, by Level A harassment, for
four marine mammal species incidental to the specified activities. As
described in the Potential Effects to Marine Mammals and Their Habitat
section, the impacts could be a small degree of AUD INJ which may or
may not manifest as PTS. Should PTS occur, at most, NMFS anticipates it
would be of a small degree; therefore, NMFS anticipates a sound would
have to be only slightly louder for it to be heard by an individual
that may incur PTS from the project. Further, PTS would only occur
within the frequency range of the source (i.e., impact pile driving,
DTH activities) which does not cover any species complete hearing
range. For most species, the frequency range of the noise produced by
the specified activities is outside their primary hearing range. While
the noise sources most overlap with low frequency cetaceans, NMFS is
proposing to authorize only 39 instances of AUD INJ for this hearing
group.
Additionally, as noted previously, some subset of individuals who
are behaviorally harassed during the activities could also
simultaneously incur some small degree of TTS for a short duration.
However, because of the anticipated small degree of possible overlap of
sound exposure, duration, and hearing frequency with species
occurrence, any TTS is expected to be limited.
Behavioral responses of marine mammals to pile removal and
installation activities in the project area, if any, are expected to be
mild, short-term, and temporary. Marine mammals within the Level B
harassment zones may not show any visual cues that they are disturbed
by activities, or they may become alert, avoid the area, leave the
area, or display other mild responses that are not observable, such as
changes in vocalization patterns. Additionally, many of the species
present in the region would be present only temporarily, based on
seasonal patterns or during active transit between other habitats. Most
likely, during the specified activities, individuals are expected to
move away from the sound source until the source ceases. An avoidance
response is most likely to
[[Page 20136]]
occur if an animal is in close proximity to a source, most notably
impact pile driving, DTH drilling, and DTH anchoring. At distance, the
severity of any behavioral response is likely to be diminished from all
of the specified activities. It is possible that avoidance or other
behavioral responses do not occur, especially for non-impulsive sources
such as vibratory pile removal and driving, given marine mammals in the
Juneau area are consistently exposed to anthropogenic noise sources
like vessel traffic. Regardless, NMFS conservatively assumes animals
disturbed by project sounds would be expected to avoid the area and use
nearby higher-quality habitats. Further, pinnipeds in the area would be
able to haul out to avoid underwater noise exposure.
The potential for all harassment is minimized by implementing the
proposed mitigation measures. During all pile removal and installation
activities, TMC would delay commencement of or shutdown activities if a
marine mammal is observed within designates zones to minimize instance
and severity of behavioral harassment and injury. These zones would be
monitored by NMFS-approved PSOs. Further, prior to impact pile driving,
TMC will implement a soft-start of the equipment prior to operating at
maximum energy. Given sufficient notice through soft start, marine
mammals are expected to move away from a sound source to avoid the
loudest noise exposure; thereby, reducing the intensity of any
behavioral reactions or injury that may occur.
Any impact on marine mammal habitat, including prey, from TMC's
proposed activities would primarily have temporary effects primarily
resulting in increased turbidity and avoidance of the immediate
vicinity around the project site by prey. Addition of the new dock
would result in permanent impacts; however, these and the expected
temporary impacts are not expected to adversely affect the degree to
which marine mammals can efficiently forage.
In summary, 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 mortality or serious injury is anticipated or proposed
for authorization, and no Level A harassment (AUD INJ) is anticipated
or proposed for authorization incidental to the Aak'w Landing
Development Project;
<bullet> Any Level A harassment (AUD INJ) is anticipated to be
slight AUD INJ, including slight PTS of a few decibels within the lower
frequencies associated with pile driving and not encompassing a
species' full hearing range;
<bullet> The anticipated incidents of Level B harassment would
result in, at worst, temporary modifications in behavior or a small
degree of TTS that would resume to baseline at the cessation of
activities or as animals move away from the source;
<bullet> The project area is located in a highly industrialized and
commercial bay; therefore, species taken are likely acclimated to
anthropogenic activities and behavioral reactions are expected to be
minor (if at all);
<bullet> Take could occur within a very small area affected by the
specified activity relative to the overall habitat ranges of all
species, does not include any rookeries nor ESA-designated critical
habitat;
<bullet> Effects on species that serve as prey for marine mammals
from the activities are primarily expected to be short-term and,
therefore, any associated impacts on marine mammal feeding are not
expected to result in significant or long-term consequences for
individuals, or to accrue adverse impacts on their populations;
<bullet> The proposed mitigation measures, such as soft-starts and
shutdowns, are expected to reduce the effects of the specified activity
to the least practicable adverse impact level; and
<bullet> TMC would employ NMFS-approved PSOs to monitor for marine
mammals and call for implementation of applicable mitigation measures;
TMC would report PSO observations to NMFS.
Based on the analysis contained herein of the likely effects of the
specified activities on marine mammals and their habitat, and taking
into consideration the implementation of the proposed monitoring and
mitigation measures, NMFS preliminarily finds that the total marine
mammal take from the specified activities would 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, so, in practice, when estimated numbers
are available, NMFS compares the number of individuals taken to the
most appropriate abundance estimate for the relevant species or stock
in determining 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 (see 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 percentage of the population that may be harassed incidental to
the specified activities assuming each take is of a different
individual is provided in table 8. The total amount of take proposed to
be authorized is less than one-third for 9 of the 10 stocks impacted
(see table 8). The total number of takes proposed to be authorized for
the Lynn Canal/St. Stephens Passage stock of harbor seals is
approximately 44 percent of the total stock abundance estimate
(13,388), assuming each take is to a different individual (i.e., no
repeated takes to the same individual). However, it is likely that a
relatively small subset of harbor seals would be incidentally harassed
repeatedly by the specified activities, and therefore, the number of
individuals taken is likely less than one-third of our stock. The stock
range extends over approximately 4500 km\2\ and harbor seals are known
to exhibit residency patterns such that repeated exposures are a likely
outcome. Overall, NMFS anticipates this percentage to be lower than
provided in table 8 for most species as repeated takes of individuals
is likely to occur given known persistence in the area, particularly
for pinnipeds.
Based on the analysis contained herein of the proposed activities
(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
In order to issue an IHA, NMFS must find that the specified
activity will not have an ``unmitigable adverse impact'' on the
subsistence uses of the affected marine mammal species or stocks by
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50
CFR 216.103 as an impact resulting from the specified activity: (1)
that is likely to reduce the availability of the species to a level
insufficient for a harvest to meet subsistence needs by: (i) causing
the marine mammals to abandon or avoid hunting areas; (ii) directly
displacing
[[Page 20137]]
subsistence users; or (iii) placing physical barriers between the
marine mammals and the subsistence hunters; and (2) that cannot be
sufficiently mitigated by other measures to increase the availability
of marine mammals to allow subsistence needs to be met.
Alaska Natives have traditionally harvested subsistence resources,
including sea lions and harbor seals, in Southeast Alaska. Since
surveys of harbor seal and sea lion subsistence harvest in Alaska began
in 1992, there have been declines in the number of households hunting
and harvesting pinnipeds in Southeast Alaska while the number of
household hunting and harvesting sea lions has remained relatively
constant at low levels (Wolfe et al., 2013). Subsistence harvest data
for the Lynn Canal/Stephens Passage stock indicates an average annual
harvest in the years 2004-2008 of 69 harbor seals; in 2011, 42 seals
were harvested, and 24 seals were harvested in 2012 (summarized in Muto
et al., 2016 from Wolfe et al., 2013). In 2012, the community of Juneau
had an estimated subsistence take of zero Steller sea lion (Wolfe et
al., 2013).
The Alaska Department of Fish and Game has designated the area
around Juneau, including ensonified waters from the project, a non-
subsistence area which is defined as an area where dependence upon
subsistence (customary and traditional uses of fish and wildlife) is
not a principal characteristic of the economy, culture, and way of life
(AS 16.05.258(c)). Regardless, the impact of the project on marine
mammals is expected to be primarily limited to mild behavioral
reactions such as temporary avoidance during pile activities, increased
swim speeds, cessation of vocalizations such that it would not affect
their availability for subsistence use.
TMC's application indicates that in June 2025, they contacted
various tribal entities including the Central Council of the Tlingit
and Haida Indian Tribes of Alaska, the Douglas Indian Association, and
the Bureau of Indian Affairs without response.
Given all this information, NMFS has preliminarily determined that
authorizing the take requested by TMC is not likely to adversely affect
the availability of any marine mammal species/stocks that would
traditionally be used for subsistence purposes, or would affect any
subsistence harvest.
<bullet> The proposed construction activities are spatially
localized within an existing waterfront development wherein marine
mammals have become acclimated to human activity;
<bullet> The proposed activities are temporary in nature;
<bullet> TMC would implement mitigation measures that minimize any
harassment to marine mammals in the action area, including
traditionally harvested species;
<bullet> NMFS expects that most of the effects on marine mammals
would not rise above behavioral impacts (i.e., Level B harassment) and
would be temporary in nature and any AUD INJ (i.e., Level A harassment)
that may occur would be a slight threshold shift and would be limited
to a few instances of take; and
<bullet> No serious injury or mortality is expected or proposed to
be authorized.
For these reasons, NMFS has preliminarily determined that there
will not be an unmitigable adverse impact on subsistence uses from
authorizing the requested take that may occur incidental to TMC's
specified activities.
Endangered Species Act
Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.)
requires that each Federal agency ensure 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 in issuing an ITA, NMFS consults internally
whenever we propose to authorize take of ESA-listed species, in this
case with the NMFS Alaska Regional Office (AKRO).
NMFS is proposing to authorize the take of the Mexico-North Pacific
stock of humpback whales and western stock of Steller sea lions, which
are listed under the ESA. The NMFS Office of Protected Resources has
requested the initiation of ESA section 7 consultation with AKRO for
the issuance of this IHA. NMFS would conclude the ESA consultation
before reaching a determination regarding the issuance of the proposed
IHA.
Proposed Authorizations
As a result of these preliminary determinations, NMFS proposes to
issue an IHA to TMC 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 comments on our analyses, the proposed authorization,
and any other aspect of this notice. We also request comments on the
potential renewal of the IHA, if issued, 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 these
IHA or a subsequent IHA renewal.
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). The request for renewal must include (1) an
explanation that the activities to be conducted under the requested
renewal IHA are identical to the activities analyzed under the initial
IHA, are a subset of the activities, or include changes so minor (e.g.,
reduction in pile size) that the changes do not affect the previous
analyses, mitigation and monitoring requirements, or take estimates
(with the exception of reducing the type or amount of take); and (2) a
preliminary monitoring report showing the results of the required
monitoring to date and an explanation showing that the monitoring
results do not indicate impacts of a scale or nature not previously
analyzed or authorized; and
<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: April 13, 2026.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries
Service.
[FR Doc. 2026-07295 Filed 4-14-26; 8:45 am]
BILLING CODE 3510-22-P
</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js" defer></script></body>
</html>Indexed from Federal Register on April 15, 2026.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.