`[Federal Register Volume 90, Number 12 (Tuesday, January 21, 2025)]
[Notices]
[Pages 7082-7101]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-01383]


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DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XE614]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental to U.S. Coast Guard Construction in 
Florence, Oregon

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

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

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SUMMARY: NMFS has received a request from the United States Coast Guard 
(USCG) for authorization to take marine mammals incidental to the 
Station Siuslaw River construction project in Florence, Oregon. 
Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting 
comments on its proposal to issue an incidental harassment 
authorization (IHA) to incidentally take marine mammals during the 
specified activities. NMFS is also requesting comments on a possible 
one-time, 1-year renewal that could be issued under certain 
circumstances and if all requirements are met, as described in Request 
for Public Comments at the end of this notice. NMFS will consider 
public comments prior to making any final decision on the issuance of 
the requested MMPA authorization and agency responses will be 
summarized in the final notice of our decision.

DATES: Comments and information must be received no later than February 
20, 2025.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources, 
National Marine Fisheries Service and should be submitted via email to 
[email protected]. Electronic copies of the application and 
supporting documents, as well as a list of the references cited in this 
document, may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities. In case of problems accessing these documents, 
please call the contact listed below.
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments, including all attachments, must 
not exceed a 25-megabyte file size. All comments received are a part of 
the public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT: Jenna Harlacher, Office of Protected 
Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are 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 and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the monitoring and 
reporting of the takings. The definitions of all applicable MMPA 
statutory terms used above are included in the relevant sections below 
and can be found in section 3 of the MMPA (16 U.S.C. 1362) and NMFS 
regulations at 50 CFR 216.103.

National Environmental Policy Act

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

Summary of Request

    On October 26, 2023, NMFS received a request from the USCG for an 
IHA to take marine mammals incidental to pile

[[Page 7083]]

driving activity associated with the Station Siuslaw River construction 
project in Florence, Oregon. Following NMFS' review of the application, 
we received a revised version of the application on April 18, 2024. 
After finalizing construction details, the USCG submitted revised 
versions on July 16, 2024 and October 16, 2024, followed by a final 
revised version on November 18, 2024, which was deemed adequate and 
complete on December 5, 2024. USCG's request is for take of harbor 
seal, California sea lion, Steller sea lion, and harbor porpoise by 
Level B harassment, and for harbor seal and harbor porpoise, Level A 
harassment. Neither USCG nor NMFS expect serious injury or mortality to 
result from this activity and, therefore, an IHA is appropriate.

Description of Proposed Activity

Overview

    The USCG requested an IHA to correct shoreline erosion and replace 
the covered mooring and appurtenant structures at USCG Station Siuslaw 
River in Florence, Oregon (Figure 1). This two-phased project entails 
both onshore and in-water construction activities including site 
preparation, demolition, shoreline stabilization measures, pile removal 
and installation, and overwater construction. Phase 1 includes onshore 
infrastructure improvements, sitework and shoreline stabilization, and 
phase 2 includes overwater and in-water construction including all pile 
install and removal.
    The only part of the project that may result in Level A and Level B 
harassment, and further analyzed in this notice, are the in-water 
construction activities associated with vibratory and impact pile 
driving (Phase 2). The USCG proposes removal of 71 timber piles via 
vibratory driving and installation of 79 total piles via vibratory and 
impact driving with an estimated 48 total days of pile removal and 
install. USCG plans to install 16-inch (in) to 20-in steel pipe piles, 
and/or 14-in H-piles for their new infrastructure. Pile driving would 
only occur within the Oregon Department of Fish and Wildlife (ODFW) 
approved in-water work window; however the proposed IHA would have a 1-
year period of effectiveness.

Dates and Duration

    The IHA would be valid from November 1, 2025 to October 31, 2026; 
however, pile driving would only occur on approximately 48 days during 
the ODFW in-water work window from November 1, 2025 to February 29, 
2026.

Specific Geographic Region

    The project location is on the east river bank of the Siuslaw 
River, approximately 5 kilometers (km) northwest of the downtown 
waterfront of the City of Florence, Oregon (Figure 1). Vegetated dunes 
in the Oregon Dunes National Recreation Area, protected by a series of 
four rock groin structures, are located on the opposite bank of the 
Station Siuslaw River.
BILLING CODE 3510-22-P

[[Page 7084]]

[GRAPHIC] [TIFF OMITTED] TN21JA25.226

BILLING CODE 3510-22-C

Detailed Description of the Specified Activity

    Equipment and most materials needed to perform onshore 
infrastructure improvements, sitework, and shoreline stabilization 
would be from a barge or similar floating work platform which would 
also serve as the primary staging area. The overall project includes 
landslide improvements, waterside improvements, in-water construction, 
over-water construction, and upland construction. Phase 1, which would 
occur on approximately 48 days, includes only onshore infrastructure 
improvements, sitework, and shoreline stabilization. All of these 
activities would occur on land, and there are no haul-outs in the 
project's immediate vicinity; therefore we don't expect take incidental 
to these activities, and they are not discussed further. This IHA only 
covers in-water construction associated with pile installation and 
removal activities that could result in take of marine mammals.
    Piles would be removed and installed during the in-water work 
window from

[[Page 7085]]

November 1, 2025 through February 28, 2026, using vibratory and impact 
hammers. USCG estimates up to three piles would be driven each 8 hour 
workday, and the actual driving time for each pile install could be as 
high as approximately 60 minutes or 15 minutes for removal. USCG would 
conduct an estimated 48 total days of pile driving activity (not all 
consecutive).
    The proposed new piles would be 16-inch (-in) to 20-in steel pipe 
piles filled with concrete, and/or 14-in steel H-Piles, which would be 
installed by vibratory driving and driven to the final tip elevation by 
impact strikes after the initial vibratory set. The exact sizes and 
quantities of pipe piles are not certain at this time and would be 
determined through the remaining design iterations by the USCG. The 
modeled pile driving scenarios accounted for the energy needed to drive 
the piles and utilized 24-in diameter pile sizes for the model, as a 
worst case scenario option. USCG would only use a vibratory hammer for 
removal of the existing piles.

                                         Table 1--Proposed Pile Driving
----------------------------------------------------------------------------------------------------------------
                                                                                     Number of    Estimated days
              Method                Pile size and type       Activity duration         piles         of work
----------------------------------------------------------------------------------------------------------------
Impact install...................  24-in...............  45 blows per minute for             79               28
                                                          27 minutes (1,230 total
                                                          blows).
                                   14 in H-pile........  45 blows per minute for
                                                          13 minutes (570 total
                                                          blows).
Vibratory install................  24-in...............  60 minutes...............           79
Vibratory removal................  24-in timber........  15 minutes...............           71               20
----------------------------------------------------------------------------------------------------------------

    The USCG has proposed in its description of the project that pile 
driving would occur only during daylight hours (no sooner than 30 
minutes after sunrise through no later than 30 minutes before sunset). 
In addition, ODFW requires all in-water construction be limited to the 
months of November through February to minimize impacts to ESA listed 
fish species.
    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, instead of reprinting the information. Additional 
information regarding population trends and threats may be found in 
NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and 
more general information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 2 lists all species or stocks for which take is expected and 
proposed to be authorized for this activity and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population (as described in NMFS' 
SARs). While no serious injury or mortality is anticipated or proposed 
to be authorized here, PBR and annual serious injury and mortality (M/
SI) from anthropogenic sources are included here as gross indicators of 
the status of the species or stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Pacific Marine Mammal SARs. All values presented in table 2 
are the most recent available at the time of publication (including 
from the draft 2023 SARs) and are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                     Table 2--Marine Mammal Species \1\ Likely To Occur Near the Project Area That May Be Taken by USCG's Activities
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         ESA/ MMPA status;   Stock abundance (CV,
             Common name                  Scientific name               Stock             strategic (Y/N)      Nmin, most recent       PBR     Annual M/
                                                                                                \2\          abundance survey) \3\               SI \4\
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                                                  Odontoceti (toothed whales, dolphins, and porpoises)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Phocoenidae (porpoises):
    Harbor Porpoise.................  Phocoena phocoena......  Central Oregon \5\.....  -, -, N             7,492 (0.421, 5,332,           53          0
                                                                                                             2022).
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                                                               Order Carnivora--Pinnipedia
--------------------------------------------------------------------------------------------------------------------------------------------------------
Family Otariidae (eared seals and
 sea lions):
    CA Sea Lion.....................  Zalophus californianus.  U.S....................  -, -, N             257,606 (N/A, 233,515,     14,011       >321
                                                                                                             2014).

[[Page 7086]]

 
    Steller Sea Lion \6\............  Eumetopias jubatus.....  Eastern................  -, -, N             36,308 (N/A, 36,308,        2,178       93.2
                                                                                                             2022).
Family Phocidae (earless seals):
    Harbor Seal.....................  Phoca vitulina.........  OR/WA Coastal..........  -, -, N             UNK (UNK, UNK, 1999)..        UND       10.6
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Information on the classification of marine mammal species can be found on the web page for The Society for Marine Mammalogy's Committee on Taxonomy
  (https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)).
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed
  under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality
  exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed
  under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g.,
  commercial fisheries, ship strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV
  associated with estimated mortality due to commercial fisheries is presented in some cases.
\5\ New stock in 2023 SARs.
\6\ Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys. Estimates provided are for the U.S.
  only.

    As indicated above, all four species (with four managed stocks) in 
table 2 temporally and spatially co-occur with the activity to the 
degree that take is reasonably likely to occur. All species that could 
potentially occur in the proposed survey areas are included in section 
3 of the IHA application on page 12. While killer whales (Orcinus 
orca), humpback whales (Megaptera novaeangliae), and gray whales 
(Eschrichtius robustus) have been sighted off the Oregon coast, the 
USCG's project is located in the Siuslaw River where these species do 
not occur. Therefor the temporal and/or spatial occurrence of these 
species is such that take is not expected to occur, and they are not 
discussed further beyond the explanation provided here and in the 
USCG's application. For more details on the species that are likely to 
occur near the project area and may be taken by USCG's activities, see 
Sections 3 and 4 of USCG's IHA application, the SARs, and NMFS' 
website.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Generalized hearing ranges were 
chosen based on the ~65 decibel (dB) threshold from composite 
audiograms, previous analyses in NMFS (2018), and/or data from Southall 
et al. (2007) and Southall et al. (2019). We note that the names of two 
hearing groups and the generalized hearing ranges of all marine mammal 
hearing groups have been recently updated (NMFS 2024) as reflected 
below in in table 3.

                  Table 3--Marine Mammal Hearing Groups
                              [NMFS, 2024]
------------------------------------------------------------------------
            Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans (baleen   7 Hz to 36 kHz.
 whales).
High-frequency (HF) cetaceans          150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
Very High-frequency (VHF) cetaceans    200 Hz to 165 kHz.
 (true porpoises, Kogia, river
 dolphins, Cephalorhynchid,
 Lagenorhynchus cruciger & L.
 australis).
Phocid pinnipeds (PW) (underwater)     40 Hz to 90 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)    60 Hz to 68 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges may not be as broad. Generalized hearing range
  chosen based on ~65 dB threshold from composite audiogram, previous
  analysis in NMFS 2018, and/or data from Southall et al. 2007; Southall
  et al. 2019. Additionally, animals are able to detect very loud sounds
  above and below that ``generalized'' hearing range.

    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2024) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section provides a discussion of the ways in which components 
of the specified activity may impact 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 this activity. The Negligible Impact Analysis 
and Determination section considers the content of this section, the 
Estimated Take of Marine Mammals section, and the Proposed Mitigation 
section, to draw conclusions regarding

[[Page 7087]]

the likely impacts of these activities on the reproductive success or 
survivorship of individuals and whether those impacts are reasonably 
expected to, or reasonably likely to, adversely affect the species or 
stock through effects on annual rates of recruitment or survival.
    Acoustic effects on marine mammals during the specified activity 
can occur from impact and vibratory pile driving. The effects of 
underwater noise from USCG's proposed activities have the potential to 
result in Level A or Level B harassment of marine mammals in the action 
area.

Description of Sound Sources

    The marine soundscape is comprised of both ambient and 
anthropogenic sounds. Ambient sound is defined as the all-encompassing 
sound in a given place and is usually a composite of sound from many 
sources both near and far. The sound level of an area is defined by the 
total acoustical energy being generated by known and unknown sources. 
These sources may include physical (e.g., waves, wind, precipitation, 
earthquakes, ice, atmospheric sound), biological (e.g., sounds produced 
by marine mammals, fish, and invertebrates), and anthropogenic sound 
(e.g., vessels, dredging, aircraft, construction).
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
shipping activity) but also on the ability of sound to propagate 
through the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al., 1995). The result is that, 
depending on the source type and its intensity, sound from the 
specified activity may be a negligible addition to the local 
environment or could form a distinctive signal that may affect marine 
mammals.
    In-water construction activities associated with the project would 
include vibratory pile removal, and impact and vibratory pile driving. 
The sounds produced by these activities fall into one of two general 
sound types: impulsive and non-impulsive. Impulsive sounds (e.g., 
explosions, gunshots, sonic booms, impact pile driving) are typically 
transient, brief (less than 1 second), broadband, and consist of high 
peak sound pressure with rapid rise time and rapid decay (ANSI, 1986; 
NIOSH, 1998; ANSI, 2005; NMFS, 2018a). Non-impulsive sounds (e.g., 
aircraft, machinery operations such as drilling or dredging, vibratory 
pile driving, and active sonar systems) can be broadband, narrowband or 
tonal, brief or prolonged (continuous or intermittent), and typically 
do not have the high peak sound pressure with raid rise/decay time that 
impulsive sounds do (ANSI, 1995; NIOSH, 1998; NMFS, 2018a). The 
distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to hearing (e.g., Ward 1997 in Southall et al., 2007).
    USCG proposes to use vibratory hammers to remove timber piles and 
impact and vibratory pile driving to install new steel pipe piles and/
or H-piles associated with the Station Siuslaw River project. Impact 
hammers operate by repeatedly dropping a heavy piston onto a pile to 
drive the pile into the substrate. Sound generated by impact hammers is 
characterized by rapid rise times and high peak levels, a potentially 
injurious combination (Hastings and Popper, 2005). Vibratory hammers 
install piles by vibrating them and allowing the weight of the hammer 
to push them into the sediment. Vibratory hammers produce significantly 
less sound than impact hammers. Peak sound pressure levels (SPLs) may 
be 180 dB or greater, but are generally 10 to 20 dB lower than SPLs 
generated during impact pile driving of the same-sized pile (Oestman et 
al., 2009). Rise time is slower, reducing the probability and severity 
of injury, and sound energy is distributed over a greater amount of 
time (Nedwell and Edwards, 2002; Carlson et al., 2005).
    The likely or possible impacts of USCG's proposed activity on 
marine mammals could involve both non-acoustic and acoustic stressors. 
Potential non-acoustic stressors could result from the physical 
presence of equipment and personnel; however, any impacts to marine 
mammals are expected to be primarily acoustic in nature. Acoustic 
stressors include effects of heavy equipment operation during pile 
installation and removal.

Acoustic Effects

    The introduction of anthropogenic noise into the aquatic 
environment from pile driving and removal is the means by which marine 
mammals may be harassed from USCG's specified activity. In general, 
animals exposed to natural or anthropogenic sound may experience 
behavioral, physiological, and/or physical effects, ranging in 
magnitude from none to severe (Southall et al., 2007, 2019). In 
general, exposure to pile driving noise has the potential to result in 
behavioral reactions (e.g., avoidance, temporary cessation of foraging 
and vocalizing, changes in dive behavior) and, in limited cases, an 
auditory threshold shift (TS). Exposure to anthropogenic noise can also 
lead to non-observable physiological responses such an increase in 
stress hormones. Additional noise in a marine mammal's habitat can mask 
acoustic cues used by marine mammals to carry out daily functions such 
as communication and predator and prey detection. The effects of pile 
driving noise on marine mammals are dependent on several factors, 
including, but not limited to, sound type (e.g., impulsive vs. non-
impulsive), the species, age and sex class (e.g., adult male vs. mom 
with calf), duration of exposure, the distance between the pile and the 
animal, received levels, behavior at time of exposure, and previous 
history with exposure (Wartzok et al., 2004; Southall et al., 2007). 
Here we discuss physical auditory effects (TSs) followed by behavioral 
effects and potential impacts on habitat.
    NMFS defines a noise-induced TS as a change, usually an increase, 
in the threshold of audibility at a specified frequency or portion of 
an individual's hearing range above a previously established reference 
level (NMFS, 2018, 2024). The amount of TS is customarily expressed in 
dB. A TS can be permanent or temporary. As described in NMFS (2018, 
2024), there are numerous factors to consider when examining the 
consequence of TS, including, but not limited to, the signal temporal 
pattern (e.g., impulsive or non-impulsive), likelihood an individual 
would be exposed for a long enough duration or to a high enough level 
to induce a TS, the magnitude of the TS, time to recovery (seconds to 
minutes or hours to days), the frequency range of the exposure (i.e., 
spectral content), the hearing and vocalization frequency range of the 
exposed species relative to the signal's frequency spectrum (i.e., how 
animal uses sound within the frequency band of the signal; e.g., 
Kastelein et al., 2014), and the overlap between the animal and the 
source (e.g., spatial, temporal, and spectral).
    Auditory Injury and Permanent Threshold Shift (PTS)--NMFS defines 
auditory injury as ``damage to the inner ear that can result in 
destruction of

[[Page 7088]]

tissue . . . which may or may not result in PTS'' (NMFS, 2024). NMFS 
defines PTS as a permanent, irreversible increase in the threshold of 
audibility at a specified frequency or portion of an individual's 
hearing range above a previously established reference level (NMFS, 
2024). PTS does not generally affect more than a limited frequency 
range, and an animal that has incurred PTS has incurred some level of 
hearing loss at the relevant frequencies; typically, animals with PTS 
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 PTS onset (see Ward et al., 1958, 
1959, 1960; Kryter et al., 1966; Miller, 1974; Ahroon et al., 1996; 
Henderson et al., 2008). PTS levels for marine mammals are estimates, 
as with the exception of a single study unintentionally inducing PTS in 
a harbor seal (Kastak et al., 2008), there are no empirical data 
measuring PTS in marine mammals largely due to the fact that, for 
various ethical reasons, experiments involving anthropogenic noise 
exposure at levels inducing PTS are not typically pursued or authorized 
(NMFS, 2018).
    Temporary Threshold Shift (TTS)--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, 2018). Based on data from cetacean TTS 
measurements (Southall et al., 2007), a TTS of 6 dB is considered the 
minimum TS clearly larger than any day-to-day or session-to-session 
variation in a subject's normal hearing ability (Schlundt et al., 2000; 
Finneran et al., 2000, 2002). As described in Finneran (2015), marine 
mammal studies have shown the amount of TTS increases with cumulative 
sound exposure level (SELcum) in an accelerating fashion: At 
low exposures with lower SELcum, the amount of TTS is 
typically small and the growth curves have shallow slopes. At exposures 
with higher SELcum, the growth curves become steeper and 
approach linear relationships with the noise SEL.
    Depending on the degree (elevation of threshold in dB), duration 
(i.e., recovery time), and frequency range of TTS, and the context in 
which it is experienced, TTS can have effects on marine mammals ranging 
from discountable to serious (similar to those discussed in Masking, 
below). For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that takes place during a time when the animal is traveling 
through the open ocean, where ambient noise is lower and there are not 
as many competing sounds present. Alternatively, a larger amount and 
longer duration of TTS sustained during time when communication is 
critical for successful mother/calf interactions could have more 
serious impacts. We note that reduced hearing sensitivity as a simple 
function of aging has been observed in marine mammals, as well as 
humans and other taxa (Southall et al., 2007), so we can infer that 
strategies exist for coping with this condition to some degree, though 
likely not without cost.
    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, and a sound must be at a higher level in order to be 
heard. In terrestrial and marine mammals, TTS can last from minutes or 
hours to days (in cases of strong TTS). In many cases, hearing 
sensitivity recovers rapidly after exposure to the sound ends. For 
cetaceans, published data on the onset of TTS are limited to captive 
bottlenose dolphin (Tursiops truncatus), beluga whale, harbor porpoise, 
and Yangtze finless porpoise (Neophocoena asiaeorientalis) (Southall et 
al., 2019). For pinnipeds in water, measurements of TTS are limited to 
harbor seals, elephant seals (Mirounga angustirostris), bearded seals 
(Erignathus barbatus) and California sea lions (Zalophus californianus) 
(Kastak et al., 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 matching previous 
predictions of TTS onset (Reichmuth et al., 2016). These studies 
examine hearing thresholds measured in marine mammals before and after 
exposure to intense or long-duration sound exposures. The difference 
between the pre-exposure and post-exposure thresholds can be used to 
determine the amount of threshold shift at various post-exposure times.
    The amount and onset of TTS depends on the exposure frequency. 
Sounds at low frequencies, well below the region of best sensitivity 
for a species or hearing group, are less hazardous than those at higher 
frequencies, near the region of best sensitivity (Finneran and 
Schlundt, 2013). At low frequencies, onset-TTS exposure levels are 
higher compared to those in the region of best sensitivity (i.e., a low 
frequency noise would need to be louder to cause TTS onset when TTS 
exposure level is higher), as shown for harbor porpoises and harbor 
seals (Kastelein et al., 2019a, 2019c). Note that in general, harbor 
seals and harbor porpoises have a lower TTS onset than other measured 
pinniped or cetacean species (Finneran, 2015). In addition, TTS can 
accumulate across multiple exposures, but the resulting TTS will be 
less than the TTS from a single, continuous exposure with the same SEL 
(Mooney et al., 2009; Finneran et al., 2010; Kastelein et al., 2014, 
2015). This means that TTS predictions based on the total, cumulative 
SEL will overestimate the amount of TTS from intermittent exposures, 
such as sonars and impulsive sources. Nachtigall et al. (2018) describe 
measurements of hearing sensitivity of multiple odontocete species 
(bottlenose dolphin, harbor porpoise, beluga, and false killer whale 
(Pseudorca crassidens)) when a relatively loud sound was preceded by a 
warning sound. These captive animals were shown to reduce hearing 
sensitivity when warned of an impending intense sound. Based on these 
experimental observations of captive animals, the authors suggest that 
wild animals may dampen their hearing during prolonged exposures or if 
conditioned to anticipate intense sounds. Another study showed that 
echolocating animals (including odontocetes) might have anatomical 
specializations that might allow for conditioned hearing reduction and 
filtering of low-frequency ambient noise, including increased stiffness 
and control of middle ear structures and placement of inner ear 
structures (Ketten et al., 2021). Data available on noise-induced 
hearing loss for mysticetes are currently lacking (NMFS, 2018). 
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 is no PTS data for cetaceans, but such 
relationships are assumed to be similar to those in humans and other 
terrestrial mammals. PTS typically occurs at exposure levels at least 
several decibels above 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

[[Page 7089]]

terrestrial mammals, a precautionary assumption is that the PTS 
thresholds for impulsive sounds (such as impact pile driving pulses as 
received close to the source) are at least 6 dB higher than the TTS 
threshold on a peak-pressure basis and PTS 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 PTS could 
occur.
    Activities for this project include impact and vibratory pile 
driving and vibratory removal. There would likely be pauses in 
activities producing the sound during each day. Given these pauses and 
the fact that many marine mammals are likely moving through the project 
areas and not remaining for extended periods of time, the potential for 
TS declines.
    Behavioral Harassment--Exposure to noise from pile driving also has 
the potential to behaviorally disturb marine mammals. Generally 
speaking, NMFS considers a behavioral disturbance that rises to the 
level of harassment under the MMPA a non-minor response--in other 
words, not every response qualifies as behavioral disturbance, and for 
responses that do, those of a higher level, or accrued across a longer 
duration, have the potential to affect foraging, reproduction, or 
survival. Behavioral disturbance may include a variety of effects, 
including subtle changes in behavior (e.g., minor or brief avoidance of 
an area or changes in vocalizations), more conspicuous changes in 
similar behavioral activities, and more sustained and/or potentially 
severe reactions, such as displacement from or abandonment of high-
quality habitat. Behavioral responses may include changing durations of 
surfacing and dives, changing direction and/or speed; reducing/
increasing vocal activities; changing/cessation of certain behavioral 
activities (such as socializing or feeding); eliciting a visible 
startle response or aggressive behavior (such as tail/fin slapping or 
jaw clapping); avoidance of areas where sound sources are located. 
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 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al., 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure.
    As noted above, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al., 
1995; Wartzok et al., 2004; National Research Council (NRC), 2005). 
Controlled experiments with captive marine mammals have showed 
pronounced behavioral reactions, including avoidance of loud sound 
sources (Ridgway et al., 1997; Finneran et al., 2003). Observed 
responses of wild marine mammals to loud pulsed sound sources (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. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder, 2007; Weilgart, 2007; NRC, 
2005). However, there are broad categories of potential response, which 
we describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark, 2000; Costa et al., 2003; Ng and Leung, 2003; Nowacek et 
al., 2004; Goldbogen et al., 2013a, 2013b). Variations in dive behavior 
may reflect interruptions in biologically significant activities (e.g., 
foraging) or they may be of little biological significance. The impact 
of an alteration to dive behavior resulting from an acoustic exposure 
depends on what the animal is doing at the time of the exposure and the 
type and magnitude of the response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. However, acoustic and movement bio-logging tools have been 
used in some cases, to infer responses of feeding to anthropogenic 
noise. For example, Blair et al. (2016) reported significant effects on 
humpback whale foraging behavior in Stellwagen Bank in response to ship 
noise including slower descent rates, and fewer side-rolling events per 
dive with increasing ship nose. In addition, Wisniewska et al. (2018) 
reported that tagged harbor porpoises demonstrated fewer prey capture 
attempts when encountering occasional high-noise levels resulting from 
vessel noise as well as more vigorous fluking, interrupted foraging, 
and cessation of echolocation signals observed in response to some 
high-noise vessel passes.
    In response to playbacks of vibratory pile driving sounds, captive 
bottlenose dolphins showed changes in target detection and number of 
clicks used for

[[Page 7090]]

a trained echolocation task (Branstetter et al. 2018). Similarly, 
harbor porpoises trained to collect fish during playback of impact pile 
driving sounds also showed potential changes in behavior and task 
success, though individual differences were prevalent (Kastelein et al. 
2019d). As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al., 
2001; Nowacek et al., 2004; Madsen et al., 2006; Yazvenko et al., 
2007). A determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationships among 
prey availability, foraging effort and success, and the life history 
stage(s) of the animal.
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that respiration rates may 
either be unaffected or could increase, depending on the species and 
signal characteristics, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al., 2001, 2005, 2006; Gailey et 
al., 2007). For example, harbor porpoise' respiration rate 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: 
127 dB re 1 [mu]Pa\2\ -s) (Kastelein et al., 2013).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al., 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al., 
1984). Avoidance may be short-term, with animals returning to the area 
once the noise has ceased (e.g., Bowles et al., 1994; Goold, 1996; 
Stone et al., 2000; Morton and Symonds, 2002; Gailey et al., 2007). 
Longer-term displacement is possible, however, which may lead to 
changes in abundance or distribution patterns of the affected species 
in the affected region if habituation to the presence of the sound does 
not occur (e.g., Blackwell et al., 2004; Bejder et al., 2006; Teilmann 
et al., 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus, 1996; Bowers et al., 2018). The result of a flight response 
could range from brief, temporary exertion and displacement from the 
area where the signal provokes flight to, in extreme cases, marine 
mammal strandings (England et al., 2001). However, it should be noted 
that response to a perceived predator does not necessarily invoke 
flight (Ford and Reeves, 2008), and whether individuals are solitary or 
in groups may influence the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fishes and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil, 1997; Fritz et al., 2002; Purser and Radford, 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch, 1992; Daan et al., 1996; Bradshaw et al., 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a 5-day period did not cause any sleep 
deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al., 2007). 
Consequently, a behavioral response lasting less than 1 day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al., 2007). Note that there is a difference between multi-day 
substantive (i.e., meaningful) behavioral reactions and multi-day 
anthropogenic activities. For example, just because an activity lasts 
for multiple days does not necessarily mean that individual animals are 
either exposed to activity-related stressors for multiple days or, 
further, exposed in a manner resulting in sustained multi-day 
substantive behavioral responses.
    Stress Responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle, 1950; 
Moberg, 2000). In many cases, an animal's first and sometimes most 
economical (in terms of energetic costs) response is behavioral 
avoidance of the potential stressor. Autonomic nervous system responses 
to stress typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al., 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its

[[Page 7091]]

energetic reserves sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al., 1996; Hood et al., 1998; Jessop et al., 2003; 
Krausman et al., 2004; Lankford et al., 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al., 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al., 2002a). For example, Rolland et al. (2012) found 
that noise reduction from reduced ship traffic in the Bay of Fundy was 
associated with decreased stress in North Atlantic right whales. These 
and other studies lead to a reasonable expectation that some marine 
mammals would experience physiological stress responses upon exposure 
to acoustic stressors and that it is possible that some of these would 
be classified as ``distress.'' In addition, any animal experiencing TTS 
would likely also experience stress responses (NRC, 2003), however 
distress is an unlikely result of this project based on observations of 
marine mammals during previous, similar projects in the area.
    Auditory Masking--Since many marine mammals rely on sound to find 
prey, moderate social interactions, and facilitate mating (Tyack, 
2008), noise from anthropogenic sound sources can interfere with these 
functions, but only if the noise spectrum overlaps with the hearing 
sensitivity of the receiving marine mammal (Southall et al., 2007; 
Clark et al., 2009; Hatch et al., 2012). Chronic exposure to excessive, 
though not high-intensity, noise could cause masking at particular 
frequencies for marine mammals that utilize sound for vital biological 
functions (Clark et al., 2009). Acoustic masking is when other noises 
such as from human sources interfere with an animal's ability to 
detect, recognize, or discriminate between acoustic signals of interest 
(e.g., those used for intraspecific communication and social 
interactions, prey detection, predator avoidance, navigation) 
(Richardson et al., 1995; Erbe et al., 2016). Therefore, under certain 
circumstances, marine mammals whose acoustical sensors or environment 
are being severely masked could also be impaired from maximizing their 
performance fitness in survival and reproduction. The ability of a 
noise source to mask biologically important sounds depends on the 
characteristics of both the noise source and the signal of interest 
(e.g., signal-to-noise ratio, temporal variability, direction), in 
relation to each other and to an animal's hearing abilities (e.g., 
sensitivity, frequency range, critical ratios, frequency 
discrimination, directional discrimination, age or TTS hearing loss), 
and existing ambient noise and propagation conditions (Hotchkin and 
Parks, 2013).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales 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 have also been documented 
lowering the bandwidth, peak frequency, and center frequency of their 
vocalizations under increased levels of background noise from large 
vessels (Castellote et al. 2012). Other alterations to communication 
signals have also been observed. For example, gray whales, in response 
to playback experiments exposing them to vessel noise, have been 
observed increasing their vocalization rate and producing louder 
signals at times of increased outboard engine noise (Dahlheim and 
Castellote, 2016). Alternatively, animals may cease sound production 
during production of aversive signals (Bowles et al., 1994).
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is human-made, it may be considered 
harassment when disrupting or altering critical behaviors. It is 
important to distinguish TTS and PTS, which persist after the sound 
exposure, from masking, which occurs during the sound exposure. Because 
masking (without resulting in TS) is not associated with abnormal 
physiological function, it is not considered a physiological effect, 
but rather a potential behavioral effect (though not necessarily one 
that would be associated with harassment).
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al., 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al., 2000; 
Foote et al., 2004; Parks et al., 2007; Di Iorio and Clark, 2010; Holt 
et al., 2009). Masking can be reduced in situations where the signal 
and noise come from different directions (Richardson et al., 1995), 
through amplitude modulation of the signal, or through other 
compensatory behaviors (Hotchkin and Parks, 2013). Masking can be 
tested directly in captive species (e.g., Erbe, 2008), but in wild 
populations it must be either modeled or inferred from evidence of 
masking compensation. There are few studies addressing real-world 
masking sounds likely to be experienced by marine mammals in the wild 
(e.g., Branstetter et al., 2013).
    Marine mammals at or near the proposed USCG project site may be 
exposed to anthropogenic noise which may be a source of masking. 
Vocalization changes may result from a need to compete with an increase 
in background noise and include increasing the source level, modifying 
the frequency, increasing the call repetition rate of vocalizations, or 
ceasing to vocalize in the presence of increased noise (Hotchkin and 
Parks, 2013). For example, in response to loud noise, beluga whales may 
shift the frequency of their echolocation clicks to prevent masking by 
anthropogenic noise (Tyack, 2000; Eickmeier and Vallarta, 2022).
    Masking occurs in the frequency band or bands that animals utilize 
and is more likely to occur in the presence of broadband, relatively 
continuous noise sources such as vibratory pile driving. Energy 
distribution of pile driving covers a broad frequency spectrum, and 
sound from pile driving would be within the audible range of pinnipeds 
and cetaceans present in the proposed action area. While some 
construction during the USCG's activities may mask

[[Page 7092]]

some acoustic signals that are relevant to the daily behavior of marine 
mammals, the short-term duration and limited areas affected make it 
very unlikely that the fitness of individual marine mammals would be 
impacted.
    Airborne Acoustic Effects--Pinnipeds that occur near the project 
site could be exposed to airborne sounds associated with construction 
activities that have the potential to cause behavioral harassment, 
depending on their distance from these activities. Airborne noise would 
primarily be an issue for pinnipeds that are swimming or hauled out 
near the project site within the range of noise levels elevated above 
airborne acoustic harassment criteria. Although pinnipeds are known to 
haul-out regularly on man-made objects, we believe that incidents of 
take resulting solely from airborne sound are unlikely given there are 
no known pinniped haulout or pupping sites within the close vicinity of 
the proposed project area; the nearest known pinniped haulout is 
located approximately 400 m from the project site for harbor seals. The 
USCG evaluated the potential for airborne acoustic effects and these 
known pinniped sites were outside the area of disturbance. 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 could be exposed to 
airborne sound that may result in behavioral harassment when looking 
with their heads above water. Most likely, airborne sound would cause 
behavioral responses similar to those discussed above in relation to 
underwater sound. For instance, anthropogenic sound could cause hauled-
out pinnipeds to exhibit changes in their normal behavior, such as 
reduction in vocalizations or cause them to temporarily abandon the 
area and move further from the source. However, these animals would 
previously 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, we do not believe that authorization of 
incidental take resulting from airborne sound for pinnipeds is 
warranted, and airborne sound is not discussed further.

Marine Mammal Habitat Effects

    The project would occur near an active marine commercial and 
industrial area. Construction activities at the Station Siuslaw River 
could have localized, temporary impacts on marine mammal habitat and 
their prey by increasing in-water SPLs and slightly decreasing water 
quality. Increased noise levels may affect acoustic habitat (see 
Auditory Masking discussion above) and adversely affect marine mammal 
prey in the vicinity of the project area (see discussion below). During 
vibratory and impact pile driving, elevated levels of underwater noise 
would ensonify a portion of the Siuslaw River, where both fish and some 
mammals occur and could affect foraging success.
    Construction activities are of short duration and would likely have 
temporary impacts on marine mammal habitat through increases in 
underwater and airborne sound. These sounds would not be detectable at 
the nearest known sea lion and harbor sea haulouts, which are beyond 
the maximum distance of predicted in-air acoustical disturbance.
    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 installation and removal of piles 
when bottom sediments are disturbed. The installation and removal of 
piles would disturb bottom sediments and may cause a temporary increase 
in suspended sediment in the project area. During pile removal, 
sediment attached to the pile moves vertically through the water column 
until gravitational forces cause it to slough off under its own weight. 
The small resulting sediment plume is expected to settle out of the 
water column within a few hours. Studies of the effects of turbid water 
on fish (marine mammal prey) suggest that concentrations of suspended 
sediment can reach thousands of milligrams per liter before an acute 
toxic reaction is expected (Burton, 1993).
    Effects to turbidity and sedimentation are expected to be short-
term, minor, and localized. Suspended sediments in the water column 
should dissipate and quickly return to background levels in all 
construction scenarios. Turbidity within the water column has the 
potential to reduce the level of oxygen in the water and irritate the 
gills of prey fish species in the proposed project area. However, 
turbidity plumes associated with the project would be temporary and 
localized, and fish in the proposed project area would be able to move 
away from and avoid the areas where plumes may occur. Therefore, it is 
expected that the impacts on prey fish species from turbidity, and 
therefore on marine mammals, would be minimal and temporary. In 
general, the area likely impacted by the proposed construction 
activities is relatively small compared to the available marine mammal 
habitat off the Coast of Oregon, and does not include any areas of 
particular importance.
    In-Water Construction Effects on Potential Prey--Sound may affect 
marine mammals through impacts on the abundance, behavior, or 
distribution of prey species (e.g., crustaceans, cephalopods, fish, 
zooplankton). Marine mammal prey varies by species, season, and 
location and, for some, is not well documented. Here, we describe 
studies regarding the effects of noise on known marine mammal prey.
    Fish utilize the soundscape and components of sound in their 
environment to perform important functions such as foraging, predator 
avoidance, mating, and spawning (e.g., Zelick et al., 1999; Fay, 2009). 
Depending on their hearing anatomy and peripheral sensory structures, 
which vary among species, fishes hear sounds using pressure and 
particle motion sensitivity capabilities and detect the motion of 
surrounding water (Fay et al., 2008). The potential effects of noise on 
fishes depends on the overlapping frequency range, distance from the 
sound source, water depth of exposure, and species-specific hearing 
sensitivity, anatomy, and physiology. Key impacts to fishes may include 
behavioral responses, hearing damage, barotrauma (pressure-related 
injuries), and mortality.
    Fish react to sounds which are especially strong and/or 
intermittent low-frequency sounds, and behavioral responses such as 
flight or avoidance are the most likely effects. Short duration, sharp 
sounds can cause overt or subtle changes in fish behavior and local 
distribution. The reaction of fish to noise depends on the 
physiological state of the fish, past exposures, motivation (e.g., 
feeding, spawning, migration), and other environmental factors. 
Hastings and Popper (2005) identified several studies that suggest fish 
may relocate to avoid certain areas of sound energy. Additional studies 
have documented effects of pile driving on fish, although several are 
based on studies in support of large, multiyear bridge construction 
projects (e.g., Scholik and Yan, 2001, 2002; Popper and Hastings, 
2009). Several studies have demonstrated that impulse sounds might 
affect the distribution and behavior of some fishes, potentially 
impacting foraging opportunities or increasing energetic costs (e.g., 
Fewtrell and McCauley, 2012; Pearson et al., 1992; Skalski et al., 
1992; Santulli et al., 1999; Paxton et al., 2017). However, some 
studies have

[[Page 7093]]

shown no or slight reaction to impulse sounds (e.g., Pena et al., 2013; 
Wardle et al., 2001; Jorgenson and Gyselman, 2009; Cott et al., 2012). 
More commonly, though, the impacts of noise on fish are temporary.
    SPLs of sufficient strength have been known to cause injury to fish 
and fish mortality. However, in most fish species, hair cells in the 
ear continuously regenerate and loss of auditory function likely is 
restored when damaged cells are replaced with new cells. Halvorsen et 
al. (2012a) showed that a TTS of 4-6 dB was recoverable within 24 hours 
for one species. Impacts would be most severe when the individual fish 
is close to the source and when the duration of exposure is long. 
Injury caused by barotrauma can range from slight to severe and can 
cause death, and is most likely for fish with swim bladders. Barotrauma 
injuries have been documented during controlled exposure to impact pile 
driving (Halvorsen et al., 2012b; Casper et al., 2013).
    The greatest potential impact to fishes during construction would 
occur during impact pile installation of 24-in steel pipe piles, which 
is estimated to occur on up to 28 days for a maximum of 1,230 strikes 
per day. In-water construction activities would only occur during 
daylight hours, allowing fish to forage and transit the project area in 
the evening. Vibratory pile driving would possibly elicit behavioral 
reactions from fishes such as temporary avoidance of the area but is 
unlikely to cause injuries to fishes or have persistent effects on 
local fish populations. Construction also would have minimal permanent 
and temporary impacts on benthic invertebrate species, a marine mammal 
prey source. In addition, it should be noted that the area in question 
is low-quality habitat since it is already highly developed and 
experiences a high level of anthropogenic noise from normal operations 
and other vessel traffic. In general, any negative impacts on marine 
mammal prey species are expected to be minor and temporary.
    Fish populations in the proposed project area that serve as marine 
mammal prey could be temporarily affected by noise from pile 
installation and removal. The frequency range in which fishes generally 
perceive underwater sounds is 50 to 2,000 Hz, with peak sensitivities 
below 800 Hz (Popper and Hastings, 2009). Fish behavior or distribution 
may change, especially with strong and/or intermittent sounds that 
could harm fishes. High underwater SPLs have been documented to alter 
behavior, cause hearing loss, and injure or kill individual fish by 
causing serious internal injury (Hastings and Popper, 2005).
    The most likely impact to fish from pile driving activities in the 
project area would be temporary behavioral avoidance of the area. The 
duration of fish avoidance of an area after pile driving stops is 
unknown, but a rapid return to normal recruitment, distribution and 
behavior is anticipated. In general, impacts to marine mammal prey 
species are expected to be minor and temporary due to the expected 
short daily duration of individual pile driving events. Additionally, 
ODFW has a pile driving construction window (November 1, 2025 through 
February 28, 2026) to further reduce effects of the proposed project on 
fish species.
    In-Water Construction Effects on Potential Foraging Habitat--The 
area likely impacted by the project is relatively small compared to the 
available habitat on the coast of Oregon and does not include any BIAs 
or ESA-designated critical habitat. The total area affected by pile 
installation and removal and the new footprint is small compared to the 
vast foraging area available to marine mammals in the area. Pile 
driving and removal at the project site would not obstruct long-term 
movements or migration of marine mammals.
    Avoidance by potential prey (i.e., fish) of the immediate area due 
to the temporary loss of this foraging habitat is also possible. The 
duration of fish and marine mammal avoidance of this area after pile 
driving stops is unknown, but a rapid return to normal recruitment, 
distribution, and behavior is anticipated. Any behavioral avoidance by 
fish or marine mammals of the disturbed area would still leave 
significantly large areas of fish and marine mammal foraging habitat in 
the nearby vicinity.
    In summary, given the short daily duration of sound associated with 
individual pile driving events and the relatively small areas being 
affected, pile driving activities associated with the proposed action 
are not likely to have a permanent adverse effect on any fish habitat, 
or populations of fish species. Any behavioral avoidance by fish of the 
disturbed area would still leave significantly large areas of fish and 
marine mammal foraging habitat in the nearby vicinity. Thus, we 
conclude that impacts of the specified activity are not likely to have 
more than short-term adverse effects on any prey habitat or populations 
of prey species. Further, any impacts to marine mammal habitat are not 
expected to result in significant or long-term consequences for 
individual marine mammals, or to contribute to adverse impacts on their 
populations.

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
proposed for authorization through the IHA, which will inform NMFS' 
consideration of ``small numbers,'' the negligible impact 
determinations, and impacts on subsistence uses.
    Harassment is the only type of take expected to result from these 
activities. Except with respect to certain activities not pertinent 
here, section 3(18) of the MMPA defines ``harassment'' as any act of 
pursuit, torment, or annoyance, which (i) has the potential to injure a 
marine mammal or marine mammal stock in the wild (Level A harassment); 
or (ii) has the potential to disturb a marine mammal or marine mammal 
stock in the wild by causing disruption of behavioral patterns, 
including, but not limited to, migration, breathing, nursing, breeding, 
feeding, or sheltering (Level B harassment).
    Authorized takes would primarily be by Level B harassment, as use 
of the acoustic sources (i.e., pile driving) has the potential to 
result in disruption of behavioral patterns for individual marine 
mammals. There is also some potential for auditory injury (AUD INJ) 
(Level A harassment) to result, primarily for very high frequency 
species and phocids because predicted AUD INJ zones are larger than for 
high-frequency species and otariids. AUD INJ is unlikely to occur for 
high-frequency species and otariids. The proposed mitigation and 
monitoring measures are expected to minimize the severity of the taking 
to the extent practicable. As described previously, no serious injury 
or mortality is anticipated or proposed to be authorized for this 
activity. Below we describe how the proposed take numbers are 
estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic criteria above which NMFS believes the best 
available science indicates marine mammals would likely 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. We note that while these 
factors can contribute to a basic calculation to provide an initial 
prediction of potential takes, additional information that can 
qualitatively inform take estimates is also sometimes available (e.g., 
previous monitoring results or average group

[[Page 7094]]

size). Below, we describe the factors considered here in more detail 
and present the proposed take estimates.

Acoustic Criteria

    NMFS recommends the use of acoustic criteria that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur AUD INJ of some degree (equated to 
Level A harassment). We note that the criteria for AUD INJ, as well as 
the names of two hearing groups, have been recently updated (NMFS 2024) 
as reflected below in the Level A Harassment section.
    Level B Harassment--Though significantly driven by received level, 
the onset of behavioral disturbance from anthropogenic noise exposure 
is also informed to varying degrees by other factors related to the 
source or exposure context (e.g., frequency, predictability, duty 
cycle, duration of the exposure, signal-to-noise ratio, distance to the 
source), the environment (e.g., bathymetry, other noises in the area, 
predators in the area), and the receiving animals (hearing, motivation, 
experience, demography, life stage, depth) and can be difficult to 
predict (e.g., Southall et al., 2007, 2021, Ellison et al., 2012). 
Based on what the available science indicates and the practical need to 
use a threshold based on a metric that is both predictable and 
measurable for most activities, NMFS typically uses a generalized 
acoustic threshold based on received level to estimate the onset of 
behavioral harassment. NMFS generally predicts that marine mammals are 
likely to be behaviorally harassed in a manner considered to be Level B 
harassment when exposed to underwater anthropogenic noise above root-
mean-squared pressure received levels (RMS SPL) of 120 dB (referenced 
to 1 micropascal (re 1 [mu]Pa)) for continuous (e.g., vibratory pile 
driving, drilling) and above RMS SPL 160 dB re 1 [mu]Pa for non-
explosive impulsive (e.g., seismic airguns) or intermittent (e.g., 
scientific sonar) sources. Generally speaking, Level B harassment take 
estimates based on these behavioral harassment thresholds are expected 
to include any likely takes by TTS as, in most cases, the likelihood of 
TTS occurs at distances from the source less than those at which 
behavioral harassment is likely. TTS of a sufficient degree can 
manifest as behavioral harassment, as reduced hearing sensitivity and 
the potential reduced opportunities to detect important signals 
(conspecific communication, predators, prey) may result in changes in 
behavior patterns that would not otherwise occur.
    USCG's proposed activity includes the use of continuous (vibratory 
pile driving) and impulsive (impact pile driving) sources, and 
therefore the RMS SPL thresholds of 120 and 160 dB re 1 [mu]Pa are 
applicable.
    Level A harassment--NMFS' Updated Technical Guidance for Assessing 
the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 
3.0) (Updated Technical Guidance, 2024) identifies dual criteria to 
assess AUD INJ (Level A harassment) to five different underwater marine 
mammal groups (based on hearing sensitivity) as a result of exposure to 
noise from two different types of sources (impulsive or non-impulsive). 
USCG's proposed activity includes the use of impulsive (impact pile 
driving) and non-impulsive (vibratory pile driving) sources.
    The 2024 Updated Technical Guidance criteria include both updated 
thresholds and updated weighting functions for each hearing group. The 
thresholds are provided in the table below. The references, analysis, 
and methodology used in the development of the criteria are described 
in NMFS' 2024 Updated Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance-other-acoustic-tools.

                          Table 4--Thresholds Identifying the Onset of Auditory Injury
----------------------------------------------------------------------------------------------------------------
                                                   AUD INJ onset acoustic thresholds * (received level)
             Hearing group              ------------------------------------------------------------------------
                                                  Impulsive                         Non-impulsive
----------------------------------------------------------------------------------------------------------------
Low-Frequency (LF) Cetaceans...........  Cell 1: Lpk,flat: 222 dB;   Cell 2: LE,LF,24h: 197 dB.
                                          LE,LF,24h: 183 dB.
High-Frequency (HF) Cetaceans..........  Cell 3: Lpk,flat: 230 dB;   Cell 4: LE,HF,24h: 201 dB.
                                          LE,HF,24h: 193 dB.
Very High-Frequency (VHF) Cetaceans....  Cell 5: Lpk,flat: 202 dB;   Cell 6: LE,VHF,24h: 181 dB.
                                          LE,VHF,24h: 159 dB.
Phocid Pinnipeds (PW) (Underwater).....  Cell 7: Lpk,flat: 223 dB;   Cell 8: LE,PW,24h: 195 dB.
                                          LE,PW,24h: 183 dB.
Otariid Pinnipeds (OW) (Underwater)....  Cell 9: Lpk,flat: 230 dB;   Cell 10: LE,OW,24h: 199 dB.
                                          LE,OW,24h: 185 dB.
----------------------------------------------------------------------------------------------------------------
* Dual metric criteria for impulsive sounds: Use whichever criteria results in the larger isopleth for
  calculating AUD INJ onset. If a non-impulsive sound has the potential of exceeding the peak sound pressure
  level criteria associated with impulsive sounds, the PK SPL criteria are recommended for consideration for non-
  impulsive sources.
Note: Peak sound pressure level (Lp,0-pk) has a reference value of 1 [micro]Pa, and weighted cumulative sound
  exposure level (LE,p) has a reference value of 1 [micro]Pa\2\s. In this table, criteria are abbreviated to be
  more reflective of International Organization for Standardization (ISO) standards (ISO 2017; ISO 2020). The
  subscript ``flat'' is being included to indicate peak sound pressure are flat weighted or unweighted within
  the generalized hearing range of marine mammals underwater (i.e., 7 Hz to 165 kHz). The subscript associated
  with cumulative sound exposure level criteria indicates the designated marine mammal auditory weighting
  function (LF, HF, and VHF cetaceans, and PW and OW pinnipeds) and that the recommended accumulation period is
  24 hours. The weighted cumulative sound exposure level criteria could be exceeded in a multitude of ways
  (i.e., varying exposure levels and durations, duty cycle). When possible, it is valuable for action proponents
  to indicate the conditions under which these criteria will be exceeded.

Ensonified Area

    Here, we describe operational and environmental parameters of the 
activity that are used in estimating the area ensonified above the 
acoustic thresholds, including source levels and transmission loss.
    The USCG opted to perform its own acoustic modeling for the Level A 
and Level B harassment isopleths using dBSea, a software developed by 
Marshall Day Acoustics for the modeling of underwater sound propagation 
in a variety of environments. Use of this model allowed USCG to 
incorporate site-specific information, therefore providing more 
accurate results than other more generalized tools. dBSea was also used 
in a previous construction project by the USCG (88 FR 77985, November 
11, 2023). NMFS has reviewed USCG's modeling and determined that it is 
acceptable for use here.
    Marshall Day Acoustics built the model by importing bathymetry data 
and placing noise sources in the

[[Page 7095]]

environment. Each source can consist of equipment chosen from either 
the standard or the user-defined databases. Noise mitigation methods 
may also be included. The user has control over the seabed and water 
properties including sound speed profile, temperature, salinity, and 
current. To examine results in more detail, the model allows users to 
plot noise levels in cross sections, or extract a detailed spectrum at 
any point in the calculation area. USCG calculated noise levels to the 
deepest depth within the project area.
    USCG derived representative acoustic modeling scenarios based on 
descriptions of the expected construction activities through 
consultations between the USCG project design and engineering teams. 
The team modeled activities that are expected to result in take of 
marine mammals (i.e., in-water pile driving and removal) at a location 
with characteristics representative of the project site. The USCG 
modeled the full range of potential water depths in the project area at 
a single representative location. As described in the Detailed 
Description of the Specified Activity section above, USCG may install a 
variety of pile types and sizes, and the exact pile sizes have not yet 
been determined. However, in an effort to avoid underestimating 
potential impacts to marine mammals, USCG conducted its analysis using 
the maximum possible pile size for each project use. Table 5 lists the 
sound source levels for each activity that USCG incorporated into the 
model. Table 6 shows the model-estimated Level A and Level B harassment 
isopleths for the proposed activities. Please refer to the Acoustic 
Assessment included in USCG's IHA application for additional details on 
the modeling principles and assumptions and a summary of construction 
and operational scenarios included in the underwater acoustic modeling 
analysis.

  Table 5--Estimates of Underwater Sound Sources * Generated During Vibratory and Impact Pile Installation and
                                             Vibratory Pile Removal
----------------------------------------------------------------------------------------------------------------
       Pile driving method         Pile type and size   db RMS    dB peak   db SEL            Reference
----------------------------------------------------------------------------------------------------------------
Impact installation.............  Steel pipe pile 24-       194       207       178  Caltrans 2020.
                                   in.
                                  H-pile.............       178       200       166  Caltrans 2020.
Vibratory installation..........  Steel pipe pile 24-       165  ........  ........  Caltrans 2020.
                                   in.
Vibratory removal...............  Timber.............       162  ........  ........  Caltrans 2020.
----------------------------------------------------------------------------------------------------------------
Note: dB peak = peak sound level; rms = root mean square; SEL = sound exposure level.
* All sound levels are referenced at 10 m.


                                Table 6--Level A and Level B Harassment Isopleths
----------------------------------------------------------------------------------------------------------------
                                                               Level A isopleth (m)
                  Size and type                  ------------------------------------------------     Level B
                                                        VHF           Phocids        Otariids      isopleth (m)
----------------------------------------------------------------------------------------------------------------
                                       Vibratory Installation and Removal
----------------------------------------------------------------------------------------------------------------
24-in steel pipe pile installation..............              58              39              17           1,117
Timber removal..................................              16              14  ..............           1,106
----------------------------------------------------------------------------------------------------------------
                                               Impact Installation
----------------------------------------------------------------------------------------------------------------
24-in steel pipe pile...........................             335             256              95             717
H-pile..........................................              96              35              18             110
----------------------------------------------------------------------------------------------------------------

Marine Mammal Occurrence and Take Calculation and Estimation

    In this section, we provide information about the occurrence of 
marine mammals, including density or other relevant information which 
would inform the take calculations and describe how the information 
provided is synthesized to produce a quantitative estimate of the take 
that is reasonably likely to occur and proposed for authorization. The 
USCG proposed using marine mammal species densities from the Pacific 
Navy Marine Species Density Database to estimate take for marine 
mammals. This database incorporates analyzed literature and research 
for marine mammal density estimates per season for regions throughout 
the U.S., and the USCG based their take estimates on regionally 
available population density estimates and site-specific knowledge. 
Although this database provides densities for all species present in 
the action area, the densities are based on offshore abundance and not 
directly relevant to occurrence within in the Siuslaw River. Following 
careful review of the analysis presented by the USCG in its 
application, including marine mammal occurrence data, NMFS has 
determined that different information inputs than those selected by the 
USCG, represent the best available scientific information for marine 
mammal abundance in the action area. These selections are discussed in 
greater detail below.
    For all species, the numbers of individuals are based on average 
group sizes from Bates et al., 2023, that described marine mammal 
occurrences near Coos Bay, Oregon in 2014 and 2015. While Coos Bay is 
south of the action area, this area is more representative of the 
action area within the Siuslaw River than the offshore data in the 
application. We derived potential take estimates from the average group 
sizes recorded over the specified period in Bates et al., 2023 and used 
the occurrences of these sightings during the surveys, along with 
sightings in OBIS-SEAMAP around the action area, to estimate our 
sighing rates in the project vicinity (table 7).

[[Page 7096]]



                Table 7--Species Rate in the Action Area
------------------------------------------------------------------------
                                                       Sighting rate for
            Species               Average group size      action area
------------------------------------------------------------------------
California sea lion............                   1.4  Group every other
                                                        day.
Steller sea lion...............                   1.8  Group every other
                                                        day.
Harbor seal....................                     1  2 groups/day.
Harbor porpoise................                   1.3  Group every other
                                                        day.
------------------------------------------------------------------------

    To calculate the total estimated takes by Level B harassment, we 
multiplied the estimated days of activity by the associated average 
group size and sighting rate for each species (table 7). There is also 
some potential for take by Level A harassment of harbor seal and harbor 
porpoise during impact pile driving due to the largest zones of each 
species being greater than the shutdown zones and because of the 
cryptic nature and assumed lower detectability of these species.
    Based on the relative proportion of the area expected to be 
ensonified above the Level A harassment threshold for phocids from 
impact pile driving (approximately 0.14 square kilometers (km\2\)) to 
the area ensonified above the Level B harassment threshold (0.59 km\2\ 
for impact pile driving), we estimated that of the total number of 
harbor seals that may be located within the greater Level B harassment 
zone, approximately 24 percent would enter the smaller Level A 
harassment zone (256 m) and stay in the zone long enough to incur 
auditory injury. Thus, we assume that 24 percent of the total estimated 
takes of harbor seals (96 individuals; see table 8) would be by Level A 
harassment. Therefore, we are proposing to authorize 23 takes of harbor 
seals by Level A harassment and 73 takes by Level B harassment (table 
8). Take by Level A harassment for harbor porpoise was calculated in 
the same way as for harbor seals. For otarrids, we are not proposing to 
authorize take by Level A harassment as the shutdown zones are much 
larger than the Level A harassment zones for most activities, and the 
likely occurrence of otariids in the action area is much lower than for 
harbor porpoise and harbor seals.

 Table 8--Proposed Take of Marine Mammals by Level A and Level B Harassment by Species and Stock and Percent of
                                                 Stock Abundance
----------------------------------------------------------------------------------------------------------------
                                                   Proposed take   Proposed take
            Species                   Stock         by Level A      by Level B    Total proposed    Percent of
                                                    harassment      harassment         take         stock taken
----------------------------------------------------------------------------------------------------------------
California sea lion...........  U.S.............               0              34              34            <0.1
Steller sea lion..............  Eastern.........               0              43              43             0.1
Harbor seal...................  Oregon/                       23              73              96             0.4
                                 Washington
                                 Coast.
Harbor porpoise...............  Central Oregon..              11              20              31             0.4
----------------------------------------------------------------------------------------------------------------

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses. NMFS regulations require applicants for incidental 
take authorizations to include information about the availability and 
feasibility (economic and technological) of equipment, methods, and 
manner of conducting the activity or other means of effecting the least 
practicable adverse impact upon the affected species or stocks, and 
their habitat (50 CFR 216.104(a)(11)).
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers two primary factors:
    1. The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat. 
This considers the nature of the potential adverse impact being 
mitigated (likelihood, scope, range). It further considers the 
likelihood that the measure would be effective if implemented 
(probability of accomplishing the mitigating result if implemented as 
planned), the likelihood of effective implementation (probability 
implemented as planned), and;
    2. The practicability of the measures for applicant implementation, 
which may consider such things as cost, and impact on operations.
    USCG must ensure that construction supervisors and crews, the 
monitoring team, and relevant USCG staff are trained prior to the start 
of all pile driving activity, so that responsibilities, communication 
procedures, monitoring protocols, and operational procedures are 
clearly understood. New personnel joining during the project must be 
trained prior to commencing work.

Pre- and Post-Activity Monitoring

     Monitoring must take place from 30 minutes prior to 
initiation of pile driving activity (i.e., pre-clearance monitoring) 
through 30 minutes post-completion of pile driving activity;
     Pre-start clearance monitoring must be conducted during 
periods of visibility sufficient for the lead PSO to determine that the 
shutdown zones indicated in table 9 are clear of marine mammals. Pile 
driving may commence following 30 minutes of observation when the 
determination is made that the shutdown zones are clear of marine 
mammals;

Soft Start

     USCG must use soft start techniques when impact pile 
driving. Soft start requires contractors to provide an initial set of 
three strikes at reduced energy, followed by a 30 second waiting 
period, then two subsequent reduced-energy strike sets. A soft start 
must be implemented at the start of each day's impact pile driving and 
at any time

[[Page 7097]]

following cessation of impact pile driving for a period of 30 minutes 
or longer; and

Shutdown Zones

    USCG would establish shutdown zones for all pile driving 
activities. The purpose of a shutdown zone is generally to define an 
area within which shutdown of the activity would occur upon sighting of 
a marine mammal (or in anticipation of an animal entering the defined 
area).
    If a marine mammal is observed entering or within the shutdown 
zones indicated in table 9, pile driving must be delayed or halted. For 
in-water heavy machinery activities other than pile driving, if a 
marine mammal comes within 10 m, work would stop and vessels would 
reduce speed to the minimum level required to maintain steerage and 
safe working conditions. A 10 m shutdown zone would also serve to 
protect marine mammals from physical interactions with project vessels 
during pile driving and other construction activities, such as barge 
positioning or drilling. If an activity is delayed or halted due to the 
presence of a marine mammal, the activity may not commence or resume 
until either the animal has voluntarily exited and been visually 
confirmed beyond the shutdown zone indicated in table 9 or 15 minutes 
have passed without re-detection of the animal. Construction activities 
must be halted upon observation of a species for which incidental take 
is not authorized or a species for which incidental take has been 
authorized but the authorized number of takes has been met entering or 
within the harassment zone.
    All marine mammals would be monitored in the Level B harassment 
zones and throughout the area as far as visual monitoring can take 
place. If a marine mammal enters the Level B harassment zone, in-water 
activities would continue and the animal's presence within the 
estimated harassment zone would be documented.
    USCG would also establish shutdown zones for all marine mammals for 
which take has not been authorized or for which incidental take has 
been authorized but the authorized number of takes has been met. These 
zones are equivalent to the Level B harassment zones for each activity. 
If a marine mammal species for which take is not authorized by this IHA 
enters the shutdown zone, all in-water activities would cease until the 
animal leaves the zone or has not been observed for at least 15 
minutes, and USCG would notify NMFS about the species and precautions 
taken. Pile driving would proceed if the non-IHA species is observed to 
leave the Level B harassment zone or if 15 minutes have passed since 
the last observation.
    If shutdown and/or clearance procedures would result in an imminent 
safety concern, as determined by USCG or its designated officials, the 
in-water activity would be allowed to continue until the safety concern 
has been addressed, and the animal would be continuously monitored.

                              Table 9--Shutdown Zones and Level B Harassment Zones
----------------------------------------------------------------------------------------------------------------
                                                              Minimum shutdown zone (m)               Level B
                      Activity                      ---------------------------------------------   harassment
                                                       VHF cetaceans       Phocid      Otariid       zone (m)
----------------------------------------------------------------------------------------------------------------
Vibratory Removal..................................                 20           20           10           1,110
Vibratory Installation.............................                 60           40           20           1,120
Impact Installation................................                200          100          100             720
----------------------------------------------------------------------------------------------------------------

Protected Species Observers (PSOs)

    The placement of PSOs during all construction activities (described 
in the Monitoring and Reporting section) would ensure that the entire 
shutdown zone is visible. Should environmental conditions deteriorate 
such that the entire shutdown zone would not be visible (e.g., fog, 
heavy rain), pile driving would be delayed until the PSO is confident 
marine mammals within the shutdown zone could be detected.
    The USCG must employ PSOs and establish monitoring locations as 
described in the application and the IHA. PSOs would monitor the full 
shutdown zones and the Level B harassment zones to the extent 
practicable. Monitoring zones provide utility for observing by 
establishing monitoring protocols for areas adjacent to the shutdown 
zones. Monitoring zones enable observers to be aware of and communicate 
the presence of marine mammals in the project areas outside the 
shutdown zones and thus prepare for a potential cessation of activity 
should the animal enter the shutdown zone.

Bubble Curtain

    A bubble curtain must be employed during all impact pile 
installation. The bubble curtain must be deployed in manner guaranteed 
to distribute air bubbles around 100 percent of the piling perimeter 
for the full depth of the water column. The lowest bubble ring must be 
in contact with the mudline for the full circumference of the ring. The 
weights attached to the bottom ring must ensure 100 percent mudline 
contact. No parts of the ring or other objects may prevent full mudline 
contact. Air flow to the bubblers must be balanced around the 
circumference of the pile.
    Based on our evaluation of USCG's proposed measures, as well as 
other measures considered by NMFS, NMFS has preliminarily determined 
that the mitigation measures provide the means effecting the least 
practicable impact on the affected species or stocks and their habitat, 
paying particular attention to rookeries, mating grounds, and areas of 
similar significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that would result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
     Occurrence of marine mammal species or stocks in the area 
in which

[[Page 7098]]

take is anticipated (e.g., presence, abundance, distribution, density);
     Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
     Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
     How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
     Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and,
     Mitigation and monitoring effectiveness.

Visual Monitoring

    Marine mammal monitoring must be conducted in accordance with the 
conditions in this section and the IHA. Marine mammal monitoring during 
pile driving activities would be conducted by PSOs meeting the 
following requirements:
     PSOs must be independent of the activity contractor (for 
example, employed by a subcontractor) and have no other assigned tasks 
during monitoring periods;
     At least one PSO would have prior experience performing 
the duties of a PSO during construction activity pursuant to a NMFS-
issued incidental take authorization;
     Other PSOs may substitute relevant experience, education 
(degree in biological science or related field), or training for prior 
experience performing the duties of a PSO during construction activity 
pursuant to a NMFS-issued incidental take authorization; and
     Where a team of three or more PSOs is required, a lead 
observer or monitoring coordinator would be designated. The lead 
observer would be required to have prior experience performing the 
duties of a PSO during construction activities pursuant to a NMFS-
issued incidental take authorization.
    PSOs must have the following additional qualifications:
     Ability to conduct field observations and collect data 
according to assigned protocols;
     Experience or training in the field identification of 
marine mammals, including the identification of behaviors;
     Sufficient training, orientation, or experience with the 
construction operation to provide for personal safety during 
observations;
     Writing skills sufficient to prepare a report of 
observations including but not limited to the number and species of 
marine mammals observed; dates and times when in-water construction 
activities were conducted; dates, times and reason for implementation 
of mitigation (or why mitigation was not implemented when required); 
and marine mammal behavior; and
     Ability to communicate orally, by radio or in person, with 
project personnel to provide real-time information on marine mammals 
observed in the area as necessary.
    USCG must assign a minimum of two PSOs to monitor during pile 
driving. One PSO must be stationed at the pile driving site, and the 
second PSO must be stationed at the best practicable location for 
monitoring the Level A and Level B harassment zones. Possible PSOs 
locations include the staging barges, on shore at the project site, or 
at the entrance to the commercial dock area at ETP. All PSOs would have 
access to high-quality binoculars, range finders to monitor distances, 
and a compass to record bearing to animals as well as radios or cells 
phones for maintaining contact with work crews.
    Monitoring would be conducted 30 minutes before, during, and 30 
minutes after all in water construction activities. In addition, PSOs 
would record all incidents of marine mammal occurrence, regardless of 
distance from activity, and would document any behavioral reactions in 
concert with distance from piles being driven or removed. Pile driving 
activities include the time to install or remove a single pile or 
series of piles, as long as the time elapsed between uses of the pile 
driving equipment is no more than 30 minutes.
    USCG shall conduct briefings between construction supervisors and 
crews, PSOs, USCG staff prior to the start of all pile driving 
activities and when new personnel join the work. These briefings would 
explain responsibilities, communication procedures, marine mammal 
monitoring protocol, and operational procedures.

Reporting

    A draft marine mammal monitoring report will be submitted to NMFS 
within 90 days after the completion of pile driving and removal 
activities, or 60 days prior to a requested date of issuance from any 
future IHAs for projects at the same location, whichever comes first. 
The report would include an overall description of work completed, a 
narrative regarding marine mammal sightings, and associated PSO data 
sheets. Specifically, the report must include:
     Dates and times (begin and end) of all marine mammal 
monitoring;
     Construction activities occurring during each daily 
observation period, including the number and type of piles driven or 
removed and by what method (i.e., impact) and the total equipment 
duration for vibratory removal for each pile or total number of strikes 
for each pile (impact driving);
     PSO locations during marine mammal monitoring;
     Environmental conditions during monitoring periods (at 
beginning and end of PSO shift and whenever conditions change 
significantly), including Beaufort sea state and any other relevant 
weather conditions including cloud cover, fog, sun glare, and overall 
visibility to the horizon, and estimated observable distance;
     Upon observation of a marine mammal, the following 
information: (1) Name of PSO who sighted the animal(s) and PSO location 
and activity at the time of sighting; (2) Time of sighting; (3) 
Identification of the animal(s) (e.g., genus/species, lowest possible 
taxonomic level, or unidentifiable), PSO confidence in identification, 
and the composition of the group if there is a mix of species; (4) 
Distance and bearing of each marine mammal observed relative to the 
pile being driven for each sightings (if pile driving was occurring at 
time of sighting); (5) Estimated number of animals (min/max/best 
estimate); (6) Estimated number of animals by cohort (adults, 
juveniles, neonates, group composition, sex class, etc.); (7) Animal's 
closest point of approach and estimated time spent within the 
harassment zone; (8) Description of any marine mammal behavioral 
observations (e.g., observed behaviors such as feeding or traveling), 
including an assessment of behavioral responses thought to have 
resulted from the activity (e.g., no response or changes in behavioral 
state such as ceasing feeding, changing direction, flushing, or 
breaching);

[[Page 7099]]

     Number of marine mammals detected within the harassment 
zones and shutdown zones; by species; and
     Detailed information about any implementation of any 
mitigation triggered (e.g., shutdowns and delays), a description of 
specific actions that ensured, and resulting changes in behavior of the 
animal(s), if any.
    If no comments are received from NMFS within 30 days, the draft 
final report would constitute the final report. If comments are 
received, a final report addressing NMFS comments must be submitted 
within 30 days after receipt of comments.

Reporting Injured or Dead Marine Mammals

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

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    To avoid repetition, our analysis applies to all species listed in 
table 2 for which take could occur, given that NMFS expects the 
anticipated effects of the proposed pile driving and removal on 
different marine mammal stocks to be similar in nature. Where there are 
meaningful differences between species or stocks, or groups of species, 
in anticipated individual responses to activities, impact of expected 
take on the population due to differences in population status, or 
impacts on habitat, NMFS has identified species-specific factors to 
inform the analysis.
    Pile driving activities associated with the USCG construction 
project have the potential to disturb or displace marine mammals. 
Specifically, the project activities may result in take, in the form of 
Level A and Level B harassment, from underwater sounds generated from 
pile driving and removal. Potential takes could occur if individuals 
are present in the ensonified zone when these activities are underway.
    The takes by Level B harassment would be due to potential 
behavioral disturbance and TTS. Takes by Level A harassment would be 
due to auditory injury. No serious injury or mortality would be 
expected, even in the absence of required mitigation measures, given 
the nature of the activities. The potential for harassment would be 
further minimized through the construction method and the 
implementation of the planned mitigation measures (see Proposed 
Mitigation section). Take by Level A harassment is proposed for harbor 
seals and harbor porpoise to account for the possibility that an animal 
could enter a Level A harassment zone prior to detection, and remain 
within that zone for a duration long enough to incur auditory injury 
before being observed and the USCG shutting down pile driving activity. 
The Level A harassment zones identified in table 6 are based upon an 
animal's exposure to pile driving of up to three of the largest steel 
piles per day. Given the short duration to vibratory or impact drive 
each pile and break between pile installations (to reset equipment and 
move piles into place), an animal would have to remain within the area 
estimated to be ensonified above the Level A harassment threshold for 
multiple hours. This is highly unlikely given marine mammal movement in 
the area. The number of takes by Level A harassment proposed for 
authorization is very low for both marine mammal species. Any take by 
Level A harassment is expected to arise from, at most, a small degree 
of auditory injury, i.e., minor degradation (likely only a few dB) of 
hearing capabilities within regions of hearing that align most 
completely with the energy produced by vibratory and impact pile 
driving (i.e. the low-frequency region below 2 kHz), not severe hearing 
impairment or impairment within the ranges of greatest hearing 
sensitivity. Animals would need to be exposed to higher levels and/or 
longer duration than are expected to occur here in order to incur any 
more than a small degree of auditory injury. Due to the small degree 
anticipated, any auditory injury incurred would not be expected to 
affect the reproductive success or survival of any individuals, much 
less result in adverse impacts on the species or stock.
    Additionally, some subset of the individuals that are behaviorally 
harassed could also simultaneously incur some small degree of TTS for a 
short duration of time. However, since the hearing sensitivity of 
individuals that incur TTS is expected to recover completely within 
minutes to hours, it is unlikely that the brief hearing impairment 
would affect the individual's long-term ability to forage and 
communicate with conspecifics, and would therefore not likely impact 
reproduction or survival of any individual marine mammal, let alone 
adversely affect rates of recruitment or survival of the species or 
stock.
    Behavioral responses of marine mammals to pile driving in the 
Siuslaw River are expected to be mild, short

[[Page 7100]]

term, and temporary. Marine mammals within the Level B harassment zones 
may not show any visual cues they are disturbed by activities or they 
could become alert, avoid the area, leave the area, or display other 
mild responses that are not observable, such as changes in vocalization 
patterns. Given that pile driving would occur for only a portion of the 
project's duration, any harassment occurring would be temporary. 
Additionally, many of the species present in region would only be 
present temporarily based on seasonal patterns or during transit 
between other habitats. These temporarily present species would be 
exposed to even smaller periods of noise-generating activity, further 
decreasing the impacts.
    Any impacts on marine mammal prey that would occur during USCG's 
proposed activity would have, at most, short-term effects on foraging 
of individual marine mammals, and likely no effect on the populations 
of marine mammals as a whole. Indirect effects on marine mammal prey 
during the construction are expected to be minor, and these effects are 
unlikely to cause substantial effects on marine mammals at the 
individual level, with no expected effect on annual rates of 
recruitment or survival.
    For all species and stocks, take would occur within a limited, 
confined area (adjacent to the project site) of the stock's range, and, 
there are no known BIAs near the project area that would be impacted by 
USCG's proposed activities. While harbor seal is the species most 
likely to occur within the immediate project area, the nearest haul out 
is outside of the ensonified areas. There are known haul out sites for 
harbor seals near the project area including across the river and 
upriver from the action area, the closest being 400 m from the project 
area. Although, the most recent survey taken of this area was in 2014. 
There are no other haul outs in the immediate project vicinity; the 
next closest haulout is 129 km away.
    In addition, it is unlikely that minor noise effects in a small, 
localized area of habitat would have any effect on the reproduction or 
survival of any individuals, much less the stocks' annual rates of 
recruitment or survival. In combination, we believe that these factors, 
as well as the available body of evidence from other similar 
activities, demonstrate that the potential effects of the specified 
activities would have only minor, short-term effects on individuals. 
The specified activities are not expected to impact rates of 
recruitment or survival and would therefore not result in population-
level impacts.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect any of the species 
or stocks through effects on annual rates of recruitment or survival:
     No serious injury or mortality is anticipated or proposed 
to be authorized;
     Take by Level A harassment is proposed for harbor seal and 
harbor porpoise only and would be very small amounts and of a low 
degree;
     For all species and stocks, the Siuslaw River is a very 
small and peripheral part of their range;
     The intensity of anticipated takes by Level B harassment 
is relatively low for all stocks. Level B harassment would be primarily 
in the form of behavioral disturbance, resulting in avoidance of the 
project areas around where impact or vibratory pile driving is 
occurring, with some low-level TTS that may limit the detection of 
acoustic cues for relatively brief amounts of time in relatively 
confined footprints of the activities;
     Effects on species that serve as prey for marine mammals 
from the activities are 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 
to adverse impacts on their populations;
     The project area does not overlap any areas of known 
important habitat for marine mammals;
     The ensonified areas are very small relative to the 
overall habitat ranges of all species and stocks; and
     The lack of anticipated significant or long-term negative 
effects to marine mammal habitat.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed 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 sections 101(a)(5)(A) and (D) of the MMPA for 
specified activities other than military readiness activities. The MMPA 
does not define small numbers and so, in practice, where estimated 
numbers are available, NMFS compares the number of individuals taken to 
the most appropriate estimation of abundance of the relevant species or 
stock in our determination of whether an authorization is limited to 
small numbers of marine mammals. When the predicted number of 
individuals to be taken is fewer than one-third of the species or stock 
abundance, the take is considered to be of small numbers. Additionally, 
other qualitative factors may be considered in the analysis, such as 
the temporal or spatial scale of the activities. For all species, the 
proposed take is below one third of the population for all marine 
mammal stocks (table 8).
    Based on the analysis contained herein of the proposed activity 
(including the proposed mitigation and monitoring measures) and the 
anticipated take of marine mammals, NMFS preliminarily finds that small 
numbers of marine mammals would be taken relative to the population 
size of the affected species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    There are no relevant subsistence uses of the affected marine 
mammal stocks or species implicated by this action. Therefore, NMFS has 
determined that the total taking of affected species or stocks would 
not have an unmitigable adverse impact on the availability of such 
species or stocks for taking for subsistence purposes.

Endangered Species Act

    Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.) 
requires that each Federal agency insure that any action it authorizes, 
funds, or carries out is not likely to jeopardize the continued 
existence of any endangered or threatened species or result in the 
destruction or adverse modification of designated critical habitat. To 
ensure ESA compliance for the issuance of IHAs, NMFS consults 
internally whenever we propose to authorize take for endangered or 
threatened species.
    No incidental take of ESA-listed species is proposed for 
authorization or expected to result from this activity. Therefore, NMFS 
has determined that formal consultation under section 7 of the ESA is 
not required for this action.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to USCG for conducting pile driving activities associated 
with the Station Siuslaw River project in Florence Oregon from November 
1, 2025 through October 31, 2026, provided the previously mentioned 
mitigation,

[[Page 7101]]

monitoring, and reporting requirements are incorporated. A draft of the 
proposed IHA can be found at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-construction-activities.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the proposed 
construction project. We also request comment on the potential renewal 
of this proposed IHA as described in the paragraph below. Please 
include with your comments any supporting data or literature citations 
to help inform decisions on the request for this IHA or a subsequent 
renewal IHA.
    On a case-by-case basis, NMFS may issue a one-time, 1-year renewal 
IHA following notice to the public providing an additional 15 days for 
public comments when (1) up to another year of identical or nearly 
identical activities as described in the Description of Proposed 
Activity section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activity section of this 
notice would not be completed by the time the IHA expires and a renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
     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 the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take).
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
     Upon review of the request for renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the mitigation and monitoring measures will remain the same and 
appropriate, and the findings in the initial IHA remain valid.

    Dated: January 15, 2025.
Kimberly Damon-Randall,
Director, Office of Protected Resources, National Marine Fisheries 
Service.
[FR Doc. 2025-01383 Filed 1-17-25; 8:45 am]
BILLING CODE 3510-22-P`