7082 Federal Register / Vol. 90, No. 12 / Tuesday, January 21, 2025 / Notices 

Given the austere and geographically 

remote operational environments OHS 

supports, our officers are also 

responsible for preventing and 

containing disease in operational 

environments as subject matter experts 

in travel medicine. The forms contained 

in this collection will be used to make 

medical readiness recommendations for 

individuals and to key leadership in 

operational environments. 

Affected Public: Individuals. 

Frequency: As needed. 

Respondent’s Obligation: Required to 

Obtain or Retain Benefits. 

Legal Authority: NAO 205–1, NOAA 

Records Management Program and 33 

U.S.C. 941. 

This information collection request 

may be viewed at www.reginfo.gov. 

Follow the instructions to view the 

Department of Commerce collections 

currently under review by OMB. 

Written comments and 

recommendations for the proposed 

information collection should be 

submitted within 30 days of the 

publication of this notice on the 

following website www.reginfo.gov/ 

public/do/PRAMain. Find this 

particular information collection by 

selecting ‘‘Currently under 30-day 

Review—Open for Public Comments’’ or 

by using the search function and 

entering the title of the collection. 

Sheleen Dumas, 

Departmental PRA Clearance Officer, Office 

of the Under Secretary for Economic Affairs, 

Commerce Department. 

[FR Doc. 2025–01314 Filed 1–17–25; 8:45 am] 

BILLING CODE 3510–12–P 

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. 

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 ITP.harlacher@

noaa.gov. 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/incidentaltake-authorizations-constructionactivities. 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-undermarine-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 


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Federal Register / Vol. 90, No. 12 / Tuesday, January 21, 2025 / Notices 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 inwater 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 


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7084 Federal Register / Vol. 90, No. 12 / Tuesday, January 21, 2025 / Notices 

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 


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Figure I-Project Location and Vicinity 
Federal Register / Vol. 90, No. 12 / Tuesday, January 21, 2025 / Notices 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 HPiles, 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

Method Pile size and type Activity duration Number 

of piles 

Estimated 

days of work 

Impact install ....... 24-in ................... 45 blows per minute for 27 minutes (1,230 total blows) ......................... 79 28 

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

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 2

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 3

PBR Annual 

M/SI 4

Odontoceti (toothed whales, dolphins, and porpoises) 

Family Phocoenidae (porpoises): 

Harbor Porpoise ................. Phocoena phocoena ................. Central Oregon 5 ....................... -, -, N 7,492 (0.421, 5,332, 

2022).

53 0 

Order Carnivora—Pinnipedia 

Family Otariidae (eared seals 

and sea lions): 

CA Sea Lion ....................... Zalophus californianus .............. U.S. ........................................... -, -, N 257,606 (N/A, 233,515, 

2014).

14,011 >321 


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7086 Federal Register / Vol. 90, No. 12 / Tuesday, January 21, 2025 / Notices 

TABLE 2—MARINE MAMMAL SPECIES 1 LIKELY TO OCCUR NEAR THE PROJECT AREA THAT MAY BE TAKEN BY USCG’S

ACTIVITIES—Continued 

Common name Scientific name Stock 

ESA/ 

MMPA 

status; 

strategic 

(Y/N) 2

Stock abundance 

(CV, Nmin, most recent 

abundance survey) 3

PBR Annual 

M/SI 4

Steller Sea Lion 6 ................ Eumetopias jubatus .................. Eastern ...................................... -, -, N 36,308 (N/A, 36,308, 

2022).

2,178 93.2 

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)). 2Endangered 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-assessmentreports-region. CV is coefficient of variation; Nmin is the minimum estimate of stock abundance. 4These 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 whales) ..................................................................................................................... 7 Hz to 36 kHz. 

High-frequency (HF) cetaceans (dolphins, toothed whales, beaked whales, bottlenose whales) ......................................... 150 Hz to 160 kHz. 

Very High-frequency (VHF) cetaceans (true porpoises, Kogia, river dolphins, Cephalorhynchid, Lagenorhynchus cruciger 

& L. australis).

200 Hz to 165 kHz. 

Phocid pinnipeds (PW) (underwater) (true seals) ................................................................................................................... 40 Hz to 90 kHz. 

Otariid pinnipeds (OW) (underwater) (sea lions and fur seals) .............................................................................................. 60 Hz to 68 kHz. 

* 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 


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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 Hpiles 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 nonacoustic 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. nonimpulsive), 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 nonimpulsive), 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 


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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 noiseinduced 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 longduration 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 


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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 inwater 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 


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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 mPa; SEL of a single 

strike: 127 dB re 1 mPa2 -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 activityrelated 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-pituitaryadrenal 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 


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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 highfrequency 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 


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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 


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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 lowquality 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 ESAdesignated 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 longterm 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 


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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-meansquared pressure received levels (RMS 

SPL) of 120 dB (referenced to 1 

micropascal (re 1 mPa)) for continuous 

(e.g., vibratory pile driving, drilling) and 

above RMS SPL 160 dB re 1 mPa for nonexplosive 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 

mPa 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/marinemammal-acoustic-technical-guidanceother-acoustic-tools. 

TABLE 4—THRESHOLDS IDENTIFYING THE ONSET OF AUDITORY INJURY

Hearing group 

AUD INJ onset acoustic thresholds * 

(received level) 

Impulsive Non-impulsive 

Low-Frequency (LF) Cetaceans ...................................... Cell 1: Lpk,flat: 222 dB; LE,LF,24h: 183 dB ......................... Cell 2: LE,LF,24h: 197 dB. 

High-Frequency (HF) Cetaceans ..................................... Cell 3: Lpk,flat: 230 dB; LE,HF,24h: 193 dB ........................ Cell 4: LE,HF,24h: 201 dB. 

Very High-Frequency (VHF) Cetaceans .......................... Cell 5: Lpk,flat: 202 dB; LE,VHF,24h: 159 dB ...................... Cell 6: LE,VHF,24h: 181 dB. 

Phocid Pinnipeds (PW) (Underwater) ............................. Cell 7: Lpk,flat: 223 dB; LE,PW,24h: 183 dB ....................... Cell 8: LE,PW,24h: 195 dB. 

Otariid Pinnipeds (OW) (Underwater) ............................. Cell 9: Lpk,flat: 230 dB; LE,OW,24h: 185 dB ....................... Cell 10: LE,OW,24h: 199 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 μPa, and weighted cumulative sound exposure level (LE,p) has a reference value of 1 μPa2s. 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 sitespecific 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 


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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-in .................................... 194 207 178 Caltrans 2020. 

H-pile ........................................................... 178 200 166 Caltrans 2020. 

Vibratory installation .................................... Steel pipe pile 24-in .................................... 165 .............. .............. Caltrans 2020. 

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

Size and type 

Level A isopleth (m) Level B 

isopleth 

VHF Phocids Otariids (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). 


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TABLE 7—SPECIES RATE IN THE ACTION AREA

Species Average group size Sighting rate for 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 

(km2)) to the area ensonified above the 

Level B harassment threshold (0.59 km2

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

Species Stock 

Proposed 

take by 

Level A 

harassment 

Proposed 

take by 

Level B 

harassment 

Total 

proposed 

take 

Percent 

of stock 

taken 

California sea lion ............................. U.S ................................................... 0 34 34 <0.1 

Steller sea lion .................................. Eastern ............................................. 0 43 43 0.1 

Harbor seal ....................................... Oregon/Washington Coast ............... 23 73 96 0.4 

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 postcompletion 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 


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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 redetection 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

Activity 

Minimum shutdown zone (m) Level B 

harassment 

zone 

(m) VHF cetaceans Phocid Otariid 

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 


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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); 


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• 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) 

(PR.ITP.MonitoringReports@noaa.gov), 

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., populationlevel 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 


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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 longterm 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, 


ddrumheller on DSK120RN23PROD with NOTICES1
Federal Register / Vol. 90, No. 12 / Tuesday, January 21, 2025 / Notices 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/incidentaltake-authorizations-constructionactivities. 

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 

DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric 

Administration 

[RTID 0648–XE618] 

Marine Mammals; File Nos. 28286 and 

22095 

AGENCY: National Marine Fisheries 

Service (NMFS), National Oceanic and 

Atmospheric Administration (NOAA), 

Commerce. 

ACTION: Notice; extension of comment 

period and proposed permit extension. 

SUMMARY: Notice is hereby given that 

the National Marine Fisheries Service is 

extending the public comment period 

associated with the notice of receipt for 

an application for a permit (File No. 

28286) to conduct research and 

enhancement activities on one stranded, 

non-releasable beluga whale 

(Delphinapterus leucas) from the 

endangered Cook Inlet distinct 

population segment (DPS). The 

application has been updated to reflect 

additional information received from 

the applicant. Additionally, we propose 

extending SeaWorld’s current permit, 

No. 22095–01, under which the subject 

beluga whale is currently held, for six 

months to allow additional processing 

of the updated application (File No. 

28286). 

DATES: The comment period for the 

notice published December 17, 2024, at 

89 FR 102117, is extended. Written 

comments must be received on or before 

March 3, 2025. 

ADDRESSES: The application for a new 

permit and related documents are 

available for review by selecting 

‘‘Records Open for Public Comment’’ 

from the ‘‘Features’’ box on the 

Applications and Permits for Protected 

Species home page, https://

apps.nmfs.noaa.gov, and then selecting 

File No. 28286 from the list of available 

applications. These documents are also 

available upon written request via email 

to NMFS.Pr1Comments@noaa.gov. 

Written comments on this application 

(File No. 28286) and the proposed 

extension to Permit No. 22095–01 

should be submitted via email to 

NMFS.Pr1Comments@noaa.gov. Please 

include File Nos. 28286 and 22095, 

respectively, in the subject line of the 

email comment. 

Those individuals requesting a public 

hearing should submit a written request 

via email to NMFS.Pr1Comments@

noaa.gov. The request should set forth 

the specific reasons why a hearing on 

this application would be appropriate. 

FOR FURTHER INFORMATION CONTACT: 

Courtney Smith, Ph.D., or Jennifer 

Skidmore, (301) 427–8401. 

SUPPLEMENTARY INFORMATION: On 

December 17, 2024 (89 FR 102117), the 

National Marine Fisheries Service 

(NMFS) published notice of a permit 

application (File No. 28286) submitted 

by SeaWorld LLC, 6240 Sea Harbor 

Drive, Orlando, FL 32821 (Responsible 

Party: Chris Dold, DVM). 

The applicant proposes to conduct 

research and enhancement activities on 

and provide long-term care for one male 

beluga whale (NOA0010477/‘‘Tyonek’’) 

from the depleted and endangered Cook 

Inlet DPS. The permit is requested for a 

5-year period. NMFS received a request 

for an extension of the public comment 

period. Additionally, NMFS received 

updated information from the applicant 

in response to preliminary questions 

from the Marine Mammal Commission 

(MMC), clarifying research sampling 

and enhancement activity details in the 

take tables, educational programs, and 

captive breeding of the subject whale. 

These changes have been incorporated 

into the application in APPS (see also 

new uploaded document, ‘‘28286_

Response to MMC Comments_

1.2.2024.pdf’’. In addition, NMFS is 

proposing to extend SeaWorld’s current 

research and enhancement permit for 

Tyonek, No. 22095–01 (75 FR 27418, 

April 17, 2024), for six months to allow 

additional processing of the updated 

application (File No. 28286). That 

extended permit would expire on 

September 15, 2025. Thus, NMFS is 

extending the public comment period 

for an additional 30 days. 

Dated: January 14, 2025. 

Julia M. Harrison, 

Chief, Permits and Conservation Division, 

Office of Protected Resources, National 

Marine Fisheries Service. 

[FR Doc. 2025–01282 Filed 1–17–25; 8:45 am] 

BILLING CODE 3510–22–P 


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