Notice

Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to U.S. Coast Guard Fast Response Cutter Homeporting in Sitka, Alaska

A Notice by the National Oceanic and Atmospheric Administration on 04/02/2026

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• Public Inspection Published Document: 2026-06394 (91 FR 16672) Document Headings ###### Department of Commerce

National Oceanic and Atmospheric Administration

1. [RTID 0648-XF546]

AGENCY:

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

ACTION:

Notice; proposed modification of an incidental harassment authorization; request for comments.

SUMMARY:

NMFS has received a request from the U.S. Coast Guard (USCG) to modify an incidental harassment authorization (IHA) that was issued to the USCG on December 20, 2024, and effective from September 1, 2026, through August 31, 2027, to take small numbers of nine species of marine mammals, by Level A and Level B harassment, incidental to the construction activities associated with fast response cutter (FRC) homeporting in Sitka, Alaska. Pursuant to the Marine Mammal Protection Act (MMPA), NMFS is requesting comments on its proposal to modify the IHA. This modification includes changes to the duration, project design, and take estimates. NMFS will consider public comments prior to making any final decision on the issuance of the requested modification of the 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 April 17, 2026.

ADDRESSES:

Comments should be addressed to Permits and Conservation Division, Office of Protected Resources, National Marine Fisheries Service and should be submitted via email to ITP.clevenstine@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/​incidental-take-authorizations-construction-activities. In case of problems accessing these documents, please call the contact listed below.

Instructions: NMFS is not responsible for comments sent by any other method, to any other address or individual, or received after the end of the comment period. Comments, including all attachments, must not exceed a 25-megabyte file size. All comments received are a part of the public record and will generally be posted online at https://www.fisheries.noaa.gov/​permit/​incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying information (e.g., name, address) voluntarily submitted by the commenter may be publicly accessible. Do not submit confidential business information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT:

Alyssa Clevenstine, Office of Protected Resources, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION:

Background

The MMPA prohibits the “take” of marine mammals, with certain exceptions. Section 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 et seq.) directs the Secretary of Commerce (as delegated to NMFS) to allow, upon request, the incidental, but not intentional, taking of small numbers of marine mammals by U.S. citizens who engage in a specified activity (other than commercial fishing) within a specified geographical region if certain findings are made and either regulations are proposed or, if the taking is limited to harassment, a notice of a proposed IHA is provided to the public for review.

Authorization for incidental takings shall be granted if NMFS finds that the taking will have a negligible impact on the species or stock(s) and will not have an unmitigable adverse impact on the availability of the species or stock(s) for taking for subsistence uses (where relevant). Further, NMFS must prescribe the permissible methods of taking; other “means of effecting the least practicable adverse impact” on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance, and on the availability of the species or stocks for taking for certain subsistence uses (referred to as “mitigation”); and requirements pertaining to the monitoring and reporting of the takings. The definitions of all applicable MMPA statutory terms used above are included in the relevant sections below (see also 16 U.S.C. 1362; 50 CFR 216.3, 216.103).

National Environmental Policy Act

To comply with the National Environmental Policy Act of 1969 (NEPA) (42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, NMFS must review our proposed action (i.e., the issuance of a modified 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 determined that the issuance of the initial IHA qualified to be categorically excluded from further NEPA review. NMFS has preliminarily determined that application of this categorical exclusion remains appropriate for this IHA modification.

History of Request

On January 19, 2024, NMFS received a request from the USCG for two IHAs to take marine mammals incidental to pile driving (installation and removal) associated with construction of two FRC homeporting docks in Seward and Sitka, Alaska. On August 26, 2024, NMFS published a Federal Register notice for the proposed IHAs (89 FR 60359). On December 20, 2024, NMFS published a Federal Register notice announcing the issuance of the IHAs to the USCG, one for Moorings Sitka effective from September 1, 2026, through August 31, 2027, and one for Moorings Seward effective from March 1, 2027, through February 29, 2028 (89 FR 104090).

On January 7, 2026, NMFS received a request from the USCG to modify the IHA for Moorings Sitka. Following NMFS' review of the request, USCG submitted a revised version on January 21, 2026, and an accompanying marine mammal monitoring plan on February 19, 2026, which NMFS determined to be adequate and complete on March 2, 2026. In the original IHA issued to the USCG for Moorings Sitka, NMFS authorized take of 9 species (14 stocks) of marine mammal by Level B harassment and, for a subset of those species, by Level A harassment (3 species (4 stocks)).

The modification was requested due to changes in project design (including ( printed page 16673) the use of different pile types and sizes), which resulted in changes to the ensonified areas and estimates of take by Level A and Level B harassment. The USCG also revised some of their proposed mitigation and monitoring measures.

Description of Proposed Activity

Overview

The USCG proposes to demolish and construct shore-side facilities at Moorings Sitka in Sitka Harbor, Alaska, to support a second FRC. The project is needed to provide adequate vessel berthing capability to support modern USCG cutters and ultimately, readiness as part of the USCG's overall mission. The USCG proposes to use impact, down-the-hole (DTH), and vibratory pile driving to install and remove piles, including steel and timber piles. These methods of pile driving will introduce underwater sounds that may result in take, by Level A and Level B harassment, of marine mammals. Pile removal may occur by vibratory, cutting, or clipping methods. Cutting and clipping are not anticipated to have the potential to result in incidental take of marine mammals because they are either above water, do not last for sufficient duration to present the reasonable potential for disruption of behavioral patterns, do not produce sound levels with likely potential to result in marine mammal harassment, or some combination of the above.

Dates and Duration

The proposed modified IHA would be valid for the statutory maximum of 1 year from the date of effectiveness. It would become effective upon written notification from the applicant to NMFS but not beginning later than 1 year from the date of issuance or extending beyond 2 years from the date of issuance. Pile removal and installation activities at Moorings Sitka would occur for a total of approximately 113 non-consecutive days; however, project delays may occur due to a number of factors, including availability of equipment and/or materials, weather-related delays, equipment maintenance and/or repair, and other contingencies.

Specific Geographic Region

There are no changes to the specific geographic region of Moorings Sitka described in the Federal Register notice for the proposed IHA (89 FR 60359, July 25, 2024). Therefore, a detailed description is not provided here. Please refer to that Federal Register notice for the description of the specific geographic region.

Detailed Description of the Specified Activity

At Moorings Sitka, removal of existing mooring dolphins and float, owned by the City of Sitka, would be required to allow for construction of a new sea-going buoy tender (hereafter WLB) pier and FRC floating dock. The planned pile extraction and installation activities from the initial IHA compared to the proposed modification are shown in table 1. Due to misidentification of pile types and sizes in the initial request for an IHA, the USCG modified their project design. The USCG still proposes to remove an existing mooring dolphin at the existing pier; however, instead of removing up to four concrete piles with vibratory extraction, three 24-inch (60.96 centimeter (cm)) dolphin piles, which are held in place with rock anchors, would be removed, along with one 24-inch (60.96 cm) steel camel pile, by vibratory extraction (table 2). Instead of installing a new mooring dolphin with three 30-inch (76.2 cm) concrete piles, the USCG would install a new mooring dolphin with four 24-inch (60.96 cm) steel piles by vibratory, impact, and DTH drilling methods (tables 2 and 3). The USCG would still remove the existing city-owned float with six 14-inch (35.56 cm) timber guide piles via vibratory extraction (table 2).

Construction of the new WLB pier would no longer include installation of 105 30-inch (76.2 cm) concrete structure piles and 54 13-inch (33.02 cm) plastic piles; instead, 95 24-inch (60.96 cm) steel piles would be installed using vibratory and impact driving and up to 25 piles would be further installed using DTH drilling methods (tables 2 and 3). This would require temporary installation and removal of 12 24-inch (60.96 cm) template piles using a vibratory hammer (table 2). In addition, the new WLB pier would require installation of 60 16-inch (40.64 cm) steel fender piles via vibratory driving (table 2).

The USCG still proposes to install a new FRC floating dock; however, the dock would now be supported by 8 24-inch (60.96 cm) steel piles which would be installed using vibratory, impact, and DTH drilling methods (tables 2 and 3).

| Project component | Pile diameter and type from initial IHA | Methods from initial IHA | Modified pile
diameter
and type | Modified methods |
| --- | --- | --- | --- | --- |
| Float Demolition | 12-inch timber | Vibratory extraction | 14-inch timber | Vibratory extraction. |
| Dolphin Demolition | 30-inch concrete | Vibratory extraction | 24-inch steel | Vibratory extraction. |
| Dolphin Installation | 30-inch concrete | Vibratory installation, impact, DTH anchor | 24-inch steel | Vibratory installation, impact, DTH anchor. |
| WLB Pier Guide | 14-inch timber | Vibratory installation | 24-inch steel | Vibratory installation. |
| WLB Pier Fender | 13-inch plastic | Vibratory installation | 16-inch steel | Vibratory installation. |
| WLB Pier Support | 30-inch concrete | Vibratory installation, impact, DTH anchor | 24-inch steel | Vibratory installation, impact, DTH anchor. |
| FRC Dock | 30-inch concrete | Vibratory installation, impact, DTH anchor | 24-inch steel | Vibratory installation, impact, DTH anchor. |
| WLB Pier Template | | | 24-inch steel | Vibratory installation. |

| Pile size and
material | Activity | Number of piles | Duration per pile
(minutes) | Piles per day | Maximum piles per day | Estimated
duration
(days) |
| --- | --- | --- | --- | --- | --- | --- |
| 24-inch steel | Extraction of existing pile | 4 | 30 | 4 | 4 | 1 |
| 14-inch timber | Extraction of existing pile | 6 | 30 | 5 | 5 | 2 |
| 24-inch steel | Installation of template pile | 12 | 15 | 4 | 4 | 3 |
| 24-inch steel | Extraction of template pile | 12 | 15 | 4 | 4 | 3 |
| 24-inch steel | Installation of support pile | 95 | 75 | 3 | 6 | 32 |
| 24-inch steel | Installation of dolphin pile | 4 | 75 | 1 | 3 | 4 |
| 24-inch steel | Installation of guide pile | 8 | 75 | 2 | 4 | 4 |
| 16-inch steel | Installation of fender pile | 60 | 30 | 5 | 8 | 12 |
| Note: USCG used the number of piles per day to calculate the total number of project days while the maximum number of piles per day was used to calculate the Level A harassment isopleths. | | | | | | |

| Pile size and material | Activity | Number of piles | Strikes per pile of impact
driving | Strikes per second of DTH drilling per pile | Duration
(minutes) of
DTH drilling
per pile | Piles
driven
per day | Maximum
piles per
day | Estimated duration
(days) |
| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 24-inch steel | Impact installation of support pile | 95 | 500 | N/A | N/A | 4 | 8 | 24 |
| 24-inch steel | Impact installation of dolphin pile | 4 | 500 | N/A | N/A | 1 | 3 | 4 |
| 24-inch steel | Impact installation of guide pile | 8 | 500 | N/A | N/A | 3 | 6 | 3 |
| 24-inch steel | DTH installation of support pile | 25 | N/A | 12.3 | 120 | 2 | 4 | 13 |
| 24-inch steel | DTH installation of dolphin pile | 4 | N/A | 12.3 | 120 | 1 | 3 | 4 |
| 24-inch steel | DTH installation of guide pile | 8 | N/A | 12.3 | 120 | 2 | 4 | 4 |
| Note: N/A = Not Applicable. USCG used the number of piles per day to calculate the total number of project days while the maximum number of piles per day was used to calculate the Level A harassment isopleths. | | | | | | | | |
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

A detailed description of the species likely to be affected by the USCG project, including brief introductions to the species and relevant stocks as well as available information regarding population trends and threats, and information regarding local occurrence, were provided in the Federal Register notice for the proposed IHA (89 FR 60359, July 25, 2024) and an updated description of marine mammal hearing was included in the notice of the final IHA (89 FR 104090, December 20, 2024); since that time, we are not aware of any changes in the status of these species and stocks; therefore, detailed descriptions are not provided here. Please refer to that Federal Register notices for these descriptions. NMFS has reviewed the draft 2024 Stock Assessment Reports for Alaska and the Pacific, information on relevant Unusual Mortality Events, and recent scientific literature, and found no new information that changes the information provided in the Federal Register notices of the proposed and final IHA. Please also refer to NMFS' website (https://www.fisheries.noaa.gov/​find-species) for generalized species accounts.

We have preliminarily determined that no new information affects our original analysis of impacts under the initial IHA. However, the USCG is no longer requesting take by Level B harassment of northern fur seal. While take of northern fur seals (Callorhinus ursinus) by Level B harassment was authorized in the initial IHA, the USCG indicated the species has not been observed in the region since 2023 and are considered to be `rare' in the area based on observational data; therefore, the USCG no longer requests take of northern fur seals.

Table 4 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 mortality and serious injury (M/SI) from anthropogenic sources are included here as gross indicators of the status of the species or stocks and other threats.

| Common name | Scientific name | Stock | ESA/MMPA status; strategic

                            (Y/N) 2 | Stock abundance

                            (CV, N min, most recent


                            abundance survey) 3 | PBR | Annual M/SI 4 |

| --- | --- | --- | --- | --- | --- | --- |
| Order Artiodactyla—Cetacea—Mysticeti (baleen whales) | | | | | | |
| Family Eschrichtiidae: | | | | | | |
| Gray Whale | Eschrichtius robustus | Eastern N Pacific | -, -, N | 26,960 (0.05, 25,849, 2016) | 801 | 131 |
| Fin Whale | Balaenoptera physalus | Northeast Pacific | E, D, Y | UND (UND, UND, 2013) | UND | 0.6 |
| Humpback Whale | Megaptera novaeangliae | Hawai'i | -, -, N | 11,278 (0.56, 7,265, 2020) | 127 | 27.09 |
| Humpback Whale | Megaptera novaeangliae | Mexico-North Pacific | T, D, Y | N/A (N/A, N/A, 2006) | UND | 0.57 |
| Minke Whale | Balaenoptera acutorostrata | Alaska | -, -, N | N/A (N/A, N/A, N/A) | UND | 0 |
| Odontoceti (toothed whales, dolphins, and porpoises) | | | | | | |
| Family Delphinidae: | | | | | | |
| Killer Whale | Orcinus orca | Eastern North Pacific Alaska Resident | -, -, N | 1,920 (N/A, 1,920, 2019) | 19 | 1.3 |
| Killer Whale | Orcinus orca | Eastern North Pacific Gulf of Alaska, Aleutian Islands and Bering Sea Transient | -, -, N | 587 (N/A, 587, 2012) | 5.9 | 0.8 |
| Killer Whale | Orcinus orca | Eastern North Pacific Northern Resident | -, -, N | 302 (N/A, 302, 2018) | 2.2 | 0.2 |
| Killer Whale | Orcinus orca | West Coast Transient | -, -, N | 349 (N/A, 349, 2018) | 3.5 | 0.4 |
| Family Phocoenidae (porpoises): | | | | | | |
| Dall's Porpoise | Phocoenoides dalli | Alaska | -, -, N | UND (UND, UND, 2015) | UND | 37 |
| Harbor Porpoise | Phocoena phocoena | Yakutat/Southeast Alaska Offshore Waters | -, -, N | N/A (N/A, N/A, 1997) | UND | 22.2 |
| Order Carnivora—Pinnipedia | | | | | | |
| Family Otariidae (eared seals and sea lions): | | | | | | |
| Steller Sea Lion | Eumetopias jubatus | Western | E, D, Y | 49,837 (N/A, 49,837, 2022) | 299 | 267 |
| Steller Sea Lion | Eumetopias jubatus | Eastern | -, -, N | 36,308 (N/A, 36,308, 2022) | 2,178 | 93.2 |
| Family Phocidae (earless seals): | | | | | | |
| Harbor Seal | Phoca vitulina | Sitka/Chatham Strait | -, -, N | 13,289 (N/A, 11,883, 2015) | 356 | 77 |
| 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/). | | | | | | |
| 2 Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock. | | | | | | |
| 3 NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/​national/​marine-mammal-protection/​marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; N min is the minimum estimate of stock abundance. | | | | | | |
| 4 These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined (e.g., commercial fisheries, vessel strike). Annual M/SI often cannot be determined precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality due to commercial fisheries is presented in some cases. | | | | | | |

Potential Effects of Specified Activities on Marine Mammals and Their Habitat

The effects of underwater noise from the USCG's construction activities have the potential to result in harassment of marine mammals in the vicinity of the project areas. The notice of proposed IHA (89 FR 60359, July 25, 2024) included a discussion of the effects of anthropogenic noise on marine mammals and the potential effects of underwater noise from the USCG's construction activities on marine mammals and their habitat. That information and analysis is referenced in this proposed IHA modification and is not repeated here; please refer to the notice of proposed IHA (89 FR 60359, July 25, 2024).

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. A description of the acoustic criteria and descriptions of Level B harassment and Level A harassment were included in the notice of proposed IHA (89 FR 60359, July 25, 2024). That information and analysis is referenced in this proposed IHA modification and is not repeated here; please refer to the notice of proposed IHA (89 FR 60359, July 25, 2024).

Ensonified Area

Here, we describe operational and environmental parameters of the proposed modified activity that are used in estimating the area ensonified above the acoustic thresholds described in the 2024 Updated Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (hereafter Updated Technical Guidance) (NMFS, 2024), including source levels and transmission loss coefficient.

The sound field in the project area is the existing background noise plus additional construction noise from the project. Marine mammals are expected to be affected via sound generated by the primary components of the project (i.e., impact pile driving, vibratory pile driving, vibratory pile removal, and DTH).

In order to calculate distances to the Level A harassment and Level B harassment thresholds for the methods and piles proposed for this project (tables 2 and 3), NMFS used acoustic monitoring data from other locations to develop proxy source levels for the various pile types, sizes, and methods (table 5). ( printed page 16676)

| Pile size and material | Activity | Peak
(dB re 1 µPa at 10 m) | RMS
(dB re 1 µPa at 10 m) | SEL single-strike (dB re 1 μPa 2 s at 10 m) | Reference |
| --- | --- | --- | --- | --- | --- |
| 14-inch timber | Vibratory | N/A | 162 | N/A | Caltrans (2020). |
| 16-inch steel | Vibratory | N/A | 163 | N/A | NMFS (2023). |
| 24-inch steel | Vibratory | N/A | 163 | N/A | NMFS (2023). |
| 24-inch steel | Impact driving | 203 | 190 | 177 | Caltrans (2015). |
| 24-inch steel | DTH drilling | 184 | 167 | 159 | Heyvaert and Reyff (2021). |
| Note: N/A = Not Applicable, m = meters. | | | | | |
NMFS recommends treating DTH systems as both impulsive and continuous, non-impulsive sound source types simultaneously. Thus, impulsive thresholds are used to evaluate Level A harassment, and continuous thresholds are used to evaluate Level B harassment. With regards to DTH mono-hammers, NMFS recommends proxy levels for Level A harassment based on available data regarding DTH systems of similar sized piles and holes.

DTH systems operate as a rotating drill head with an attached hammer that fractures bedrock on each rotation. The strike rate (in strikes per second) is directly related to the speed of the drill rotation. Measurements of DTH drilling taken primarily in southeast Alaska have recorded a range of strike rates for 24-inch (60.96 cm) diameter holes between 9 and 15.5 strikes per second, with an average of approximately 12.3 strikes per second (Heyvaert and Reyff, 2021; Denes et al., 2016, Miner et al., 2023, Illingworth and Rodkin, 2023; Reyff et al., 2025). While USCG proposed a rate of 15 strikes per second in their modification request, this value is at the high end of measured rates, which increases the ensonified areas relative to lower strike rates, potentially producing overly-conservative isopleths. NMFS instead proposes the average of the measured values for this pile size, and has used 12.3 strikes per second in our calculations.

Level B Harassment Zones

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

TL = B * log 10 (R 1 / R 2),

Where:

TL = transmission loss in dB,

B = transmission loss coefficient; for practical spreading equals 15,

R 1 = the distance of the modeled SPL from the driven pile, and

R 2 = the distance from the driven pile of the initial measurement.

The recommended TL coefficient for most nearshore environments is the practical spreading value of 15. This value results in an expected propagation environment that would lie between spherical and cylindrical spreading loss conditions, which is the most appropriate assumption for the USCG's proposed activities. The Level B harassment zones and approximate amount of area ensonified for the proposed underwater activities are shown in table 6.

Level A Harassment Zones

The ensonified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component. Therefore, NMFS developed an optional User Spreadsheet tool to accompany the 2024 Updated Technical Guidance that can be used to relatively simply predict an isopleth distance for use in conjunction with marine mammal density or occurrence to help predict potential takes. We note that because of some of the assumptions included in the methods underlying this optional tool, we anticipate that the resulting isopleth estimates are typically going to be overestimates of some degree, which may result in an overestimate of potential take by Level A harassment. However, this optional tool offers a practical, alternative way to estimate isopleth distances when more sophisticated modeling methods are not available or practical. For stationary sources such as pile driving, the optional User Spreadsheet tool predicts the distance at which, if a marine mammal remained at that distance for the duration of the activity, it would be expected to incur AUD INJ. Inputs used in the optional User Spreadsheet tool include values in tables 2 and 3 (e.g., number of piles per day, duration and/or strikes per pile), and table 5 (i.e., source levels), and the resulting estimated isopleths are reported in table 6.

| Pile size and
material | Activity | Distance to
Level A
(m) for low-
frequency
cetaceans | Distance to
Level A
(m) for high-
frequency
cetaceans | Distance to
Level A
(m) for very
high
frequency
cetaceans | Distance to
Level A
(m) for
phocids
in water | Distance to
Level A
(m) for
otariids
in water | Distance to
Level B
(m) | Total
Level B
ensonified
area

                            (km 2) |

| --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 24-inch steel | Vibratory extraction of existing pile | 19.9 | 7.6 | 16.3 | 25.6 | 8.6 | 7,356.4 | 7.674 |
| 14-inch timber | Vibratory extraction of existing pile | 19.8 | 7.6 | 16.2 | 25.5 | 8.6 | 6,309.6 | 6.409 |
| 24-inch steel | Vibratory installation of template pile | 12.5 | 4.8 | 10.2 | 16.1 | 5.4 | 7,356.4 | 7.674 |
| 24-inch steel | Vibratory extraction of template pile | 12.5 | 4.8 | 10.2 | 16.1 | 5.4 | 7,356.4 | 7.674 |
| 24-inch steel | Vibratory installation of support pile | 48 | 18.5 | 39.2 | 61.8 | 20.8 | 7,356.4 | 7.674 |
| 24-inch steel | Vibratory installation of dolphin pile | 30.3 | 11.6 | 24.7 | 39 | 13.1 | 7,356.4 | 7.674 |
| 24-inch steel | Vibratory installation of guide pile | 36.7 | 14.1 | 29.9 | 47.2 | 15.9 | 7,356.4 | 7.674 |
| 16-inch steel | Vibratory installation of fender pile | 31.6 | 12.1 | 25.8 | 40.7 | 13.7 | 7,356.4 | 7.674 |
| 24-inch steel | Impact installation of support pile | 998.2 | 127.4 | 1,544.6 | 886.7 | 330.5 | 1,000 | 0.562 |
| 24-inch steel | Impact installation of dolphin pile | 519.1 | 66.2 | 803.2 | 461.1 | 171.9 | 1,000 | 0.562 |
| 24-inch steel | Impact installation of guide pile | 824 | 105.1 | 1,275.1 | 732 | 272.8 | 1,000 | 0.562 |
| 24-inch steel | DTH installation of support pile | 1,251.3 | 159.6 | 1,936.4 | 1,111.6 | 414.4 | 13,593.6 | 13.716 |
| 24-inch steel | DTH installation of dolphin pile | 1,032.9 | 131.8 | 1,598.4 | 917.6 | 342 | 13,593.6 | 13.716 |
| 24-inch steel | DTH installation of guide pile | 1,251.3 | 159.6 | 1,936.4 | 1,111.6 | 414.4 | 13,593.6 | 13.716 |
| Note: m = meters. Distances refer to the maximum radius of the isopleth; the actual isopleth may be truncated by landforms. The values provided for distance of the Level A harassment isopleth represent the distance at which an animal may incur auditory injury (AUD INJ) if that animal remained at that distance for the entire duration of the activity within a 24-hour period. | | | | | | | | |
For a given activity, Level A harassment zones are typically smaller than Level B harassment zones. However, in rare cases, the maximum calculated distance to the Level A harassment threshold is greater than the maximum calculated distance to the Level B harassment threshold (e.g., values for impact pile driving of 24-inch steel support and guide piles for very high-frequency (VHF) cetaceans) (table 6). Calculations of Level A harassment isopleths include a duration component that, in the case of impact pile driving and DTH methods, is estimated through the total number of expected daily strikes within a 24-hour period and the associated pulse duration. When analyzing potential acoustic impacts for a stationary sound source such as impact pile driving or DTH, we assume that an animal would be exposed to all of the strikes expected for that activity within that 24-hour period. In contrast, calculation of Level B harassment isopleths does not include a duration component. Due to differences in the parameters that characterize each form of harassment, it is assumed that Level B harassment occurs instantaneously rather than building through exposure to a series of hammer strikes over a longer duration. Thus, depending on the duration included in the calculation, the calculated radii to Level A harassment isopleths can be larger than the calculated radii to the Level B harassment isopleth for the same activity.

Marine Mammal Occurrence

In this section we provide information about the occurrence of marine mammals, including relevant information which will inform the take calculations. Available information regarding marine mammal occurrence in the project area includes monitoring data, prior incidental take authorizations, and ESA consultations on previous projects. The USCG modified their take request for Dall's porpoise, relying on occurrence information rather than density data to estimate take at Moorings Sitka, the latter of which was used to estimate take for the initial IHA. There are no other changes to the marine mammal occurrence and group size described in the Federal Register notice for the proposed IHA (89 FR 60359, July 25, 2024). Therefore, a detailed description of occurrence and group size are not provided here. Daily occurrence probability of each marine mammal species is based on consultation with previous monitoring reports, local researchers, and marine professionals. Occurrence probability estimates are based on conservative density approximations for each species and factor in historic data of occurrence, seasonality, and group size in Sitka Sound and Sitka Channel. A summary of occurrence is shown in table 7. Group size is based on the best available published research for these species and their presence in the project areas.

| Species | Group size | Occurrence
frequency
(group size
per time
period) |
| --- | --- | --- |
| Steller sea lion | 2 | 1-2 per day. |
| Harbor seal | 2 | 1-2 per day. |
| Killer whale | 7 | 4 per month. |
| Harbor porpoise | 5 | 4 per month. |
| Dall's porpoise | 6 | 2 per month. |
| Humpback whale | 4 | 4 per month. |
| Gray whale | 4 | 2 per month. |
| Minke whale | 4 | 2 per month. |

Take Estimation

Here we describe how the information provided above is synthesized to produce a quantitative estimate of the take that is reasonably likely to occur and proposed for authorization.

Estimated occurrence of species in the initial IHA did not change but were converted to the number of groups per day or per month (i.e., species whose occurrence was one group per week is now four groups per month). When the group size estimated in the initial IHA was used in the updated take calculations, the group size was rounded up to the next full individual (e.g., minke whales had an occurrence estimate of one group of 3.5 individuals per 2 weeks). In the updated take estimates, this becomes two groups of four individuals per month.

To calculate take by Level A harassment, the expected occurrence (group size and estimated frequency) was multiplied by the number of days that the Level A harassment isopleth exceeded the proposed shutdown zone. Level A take is thus proposed for VHF cetaceans, phocids (PW), and otariids (OW) for all 52 days of proposed impact pile driving and DTH drilling.

The following equations were used to estimate take by Level A harassment:

Monthly estimated take = estimated monthly frequency × group size × (days of pile driving activity/30 days per month)

Daily estimated take = estimated daily frequency × group size × days of pile driving activity

To calculate take by Level B harassment, the expected occurrence (group size and estimated frequency) was multiplied by the total number of days of pile driving. For species where take by Level A harassment is requested, the estimated take by Level A harassment was subtracted from the takes by Level B harassment.

The following equations were used to estimate take by Level B harassment:

Monthly estimated take = estimated monthly frequency × group size × (days of pile driving activity/30 days per month)−Level A take

Daily estimated take = estimated daily frequency × group size × days of pile driving activity−Level A take

Table 8 summarizes proposed amounts of take by both Level A and Level B harassment, as well as the percentage of each stock expected to be taken, from the modified activities. ( printed page 16678)

| Species | Stock | Level A
harassment | Level B
harassment | SAR
abundance | Instances of
take as a
percentage of
population |
| --- | --- | --- | --- | --- | --- |
| Steller sea lion | Western | 2 | 8 | 49,837 | <1 |
| Steller sea lion | Eastern | 102 | 340 | 36,308 | <1 |
| Harbor seal | Sitka/Chatham Strait | 104 | 348 | 13,289 | 3.4 |
| Killer whale * | Eastern North Pacific Alaska Resident | 0 | 64 | 1,920 | 3.3 |
| Killer whale * | Eastern North Pacific Gulf of Alaska, Aleutian Islands and Bering Sea Transient | 0 | 20 | 587 | 3.4 |
| Killer whale * | Eastern North Pacific Northern Resident | 0 | 10 | 302 | 3.3 |
| Killer whale * | West Coast Transient | 0 | 12 | 349 | 3.4 |
| Harbor porpoise | Yakutat/Southeast Alaska Offshore Waters | 35 | 41 | N/A | N/A |
| Dall's porpoise | Alaska | 21 | 25 | UND | UND |
| Humpback whale | Hawai'i | 0 | 60 | 11,278 | <1 |
| Humpback whale | Mexico-North Pacific | 0 | 1 | N/A | <1 |
| Gray whale | Eastern North Pacific | 0 | 31 | 26,960 | <1 |
| Minke whale | Alaska | 0 | 31 | N/A | N/A |
| Note: N/A = Not Applicable; UND = Undetermined; Steller sea lion stock attribution: 97.8 percent Eastern DPS and 2.2 percent Western DPS; Humpback whale stock attribution: 98 percent Hawai'i and 2 percent Mexico-North Pacific. | | | | | |
| * Percent of stock impacted for killer whales was estimated assuming each stock is taken in proportion to its population size from the total take. The Alaska Resident, Gulf of Alaska, Northern Resident, and West Coast Transient stocks are expected at Moorings Sitka, and the Alaska Resident stock represents approximately 60 percent of the available animals, the Gulf of Alaska stock represents approximately 19 percent, the Northern Resident stock represents approximately 10 percent, and the West Coast Transient represents approximately 11 percent. Takes were then calculated based on the proportional representation of available stocks, which results in 64 Level B harassment takes of the Alaska Resident stock, 20 Level B harassment takes of the Gulf of Alaska stock, 10 Level B harassment takes of the Northern Resident stock, and 12 Level B harassment takes of the West Coast Transient stock. | | | | | |

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, as well as subsistence uses. This considers the nature of the potential adverse impact being mitigated (likelihood, scope, range). It further considers the likelihood that the measure will be effective if implemented (probability of accomplishing the mitigating result if implemented as planned), the likelihood of effective implementation (probability implemented as planned); and

(2) The practicability of the measures for applicant implementation, which may consider such things as cost, and impact on operations.

The mitigation requirements described in the following were proposed by the USCG in its adequate and complete request for IHA modification or are the result of subsequent coordination between NMFS and the USCG. The USCG has agreed that all of the mitigation measures are practicable. NMFS has fully reviewed the specified activities and the mitigation measures to determine if the mitigation measures would result in the least practicable adverse impact on marine mammals and their habitat, as required by the MMPA, and has determined the proposed measures are appropriate. NMFS describes these below as proposed mitigation requirements and has included them in the proposed IHA modification.

The 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 and DTH 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;
• Employ three to six PSOs and establish monitoring locations as described in the Marine Mammal Monitoring Plan (hereafter Monitoring Plan) and the IHA. The USCG must monitor the project area to the maximum extent possible based on the required number of PSOs, required monitoring locations, and environmental conditions. For all pile driving and removal at least one PSO must be used. The PSO will be stationed as close to the activity as possible;
• The placement of the PSOs during all pile driving and removal and DTH activities will ensure that the entire shutdown zone is visible during pile installation;
• Monitoring must take place from 30 minutes prior to initiation of pile driving or DTH activity (i.e., pre-activity monitoring) through 30 minutes post-activity of pile driving or DTH activity;
• Pre-activity 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 and DTH may commence following 30 minutes of observation when the determination is made that the shutdown zones are clear of marine mammals;
• The USCG must use soft start techniques when impact pile driving. Soft start requires contractors to provide an initial set of three strikes at reduced ( printed page 16679) energy, followed by a 30-second waiting period, then two subsequent reduced energy strike sets. A soft start must be implemented at the start of each day's impact pile driving and at any time following cessation of impact pile driving for a period of 30 minutes or longer; and
• If a marine mammal is observed entering or within the shutdown zones indicated in table 9, pile driving and DTH must be delayed or halted. If pile driving is delayed or halted due to the presence of a marine mammal, the activity may not commence or resume until either the animal has voluntarily exited and been visually confirmed beyond the shutdown zone (table 9) or 15 minutes have passed without re-detection of the animal. In their modification request, the USCG stated the shutdown zones outlined in the initial IHA for pinnipeds are no longer feasible for the modified project. On the opposite side of the channel there are two seafood processing plants that are roughly 210 m and 450 m from the project location. These facilities, which can attract pinnipeds, are within the estimated Level A harassment isopleths for impact and DTH activities for both pinniped hearing groups, and marine mammals near these facilities are likely to lead to delays to the start of construction as well as an increased number of shutdowns. The USCG requested to use a minimum 10-m shutdown zone for all activities rather than the 30-m minimum shutdown zone described in the issued IHA.

Further, the USCG indicated it is no longer practicable to have vessel-based PSOs monitor the shutdown zones for DTH activity. Instead, PSOs will be land-based and stationed at up to six different locations depending on the in-water activity (see the Proposed Monitoring and Reporting section for more information).

| Pile size and
material | Activity | Minimum
shutdown zone (m) for LF
cetaceans | Minimum shutdown zone (m) for HF cetaceans | Minimum shutdown zone (m) for VHF cetaceans | Minimum shutdown zone (m) for PW | Minimum shutdown zone (m) for OW | Level B
harassment
monitoring zone (m) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 24-inch steel | Vibratory extraction of existing pile | 20 | 10 | 20 | 30 | 10 | 7,360 |
| 14-inch timber | Vibratory extraction of existing pile | 20 | 10 | 20 | 30 | 10 | 6,310 |
| 24-inch steel | Vibratory installation of template pile | 15 | 10 | 15 | 20 | 10 | 7,360 |
| 24-inch steel | Vibratory extraction of template pile | 15 | 10 | 15 | 20 | 10 | 7,360 |
| 24-inch steel | Vibratory installation of support pile | 50 | 20 | 40 | 65 | 25 | 7,360 |
| 24-inch steel | Vibratory installation of dolphin pile | 35 | 15 | 25 | 40 | 15 | 7,360 |
| 24-inch steel | Vibratory installation of guide pile | 40 | 15 | 30 | 50 | 20 | 7,360 |
| 16-inch steel | Vibratory installation of fender pile | 35 | 15 | 30 | 45 | 15 | 7,360 |
| 24-inch steel | Impact installation of support pile | 1,000 | 130 | 100 | 100 | 100 | 1,000
(VHF: 1,545 ) |
| 24-inch steel | Impact installation of dolphin pile | 520 | 70 | 100 | 100 | 100 | 1,000 |
| 24-inch steel | Impact installation of guide pile | 830 | 110 | 100 | 100 | 100 | 1,000
(VHF: 1,280 ) |
| 24-inch steel | DTH installation of support pile | 1,255 | 160 | 100 | 100 | 100 | 13,600 |
| 24-inch steel | DTH installation of dolphin pile | 1,035 | 135 | 100 | 100 | 100 | 13,600 |
| 24-inch steel | DTH installation of guide pile | 1,255 | 160 | 100 | 100 | 100 | 13,600 |
| Note: m = meters. Distances (m) refer to the maximum radius of the Level A harassment and Level B harassment isopleths and is rounded. The actual zone may be truncated by landforms. The values provided for calculated distances of the Level A harassment isopleth represent the distance at which an animal may incur AUD INJ if that animal remained at that distance for the entire duration of the activity within a 24-hour period. | | | | | | | |
| * For VHF cetaceans, the shutdown zone is larger than the monitoring zone; therefore, the extent of the shutdown zone is the monitoring zone for VHF cetaceans during impact installation of piles. | | | | | | | |
NMFS conducted an independent evaluation of the proposed measures and has preliminarily determined that the proposed mitigation measures provide the means of effecting the least practicable impact on the affected species or stocks and their habitat, paying particular attention to rookeries, mating grounds, and areas of similar significance.

Proposed Monitoring and Reporting

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

Monitoring and reporting requirements prescribed by NMFS should contribute to improved understanding of one or more of the following:

• Occurrence of marine mammal species or stocks in the area in which take is anticipated (e.g., presence, abundance, distribution, density);
• Nature, scope, or context of likely marine mammal exposure to potential stressors/impacts (individual or cumulative, acute or chronic), through better understanding of: (1) action or environment (e.g., source characterization, propagation, ambient noise); (2) affected species (e.g., life history, dive patterns); (3) co-occurrence of marine mammal species with the 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. The monitoring and reporting requirements described in the following were proposed by the USCG in its adequate and complete modification request and Protected Species Monitoring and Mitigation Plan ( printed page 16680) (hereafter Monitoring Plan) and/or are the result of subsequent coordination between NMFS and the USCG. The USCG has agreed to the requirements. NMFS describes these below as requirements and has included them in the proposed IHA modification. Marine mammal monitoring must be conducted in accordance with the Monitoring Plan provided by the USCG for this proposed IHA modification and is available at https://www.fisheries.noaa.gov/​action/​incidental-take-authorization-united-states-coast-guards-fast-response-cutter-homeporting.

Visual Monitoring

Marine mammal monitoring must be conducted in accordance with the conditions in this section and this IHA. Marine mammal monitoring during pile driving activities would be conducted by up to six PSOs meeting NMFS' standards and in a manner consistent with the following:

• PSOs must be independent of the activity contractor (e.g., 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 other 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;
• Where a team of three or more PSOs is required, a lead observer or monitoring coordinator must be designated. The lead observer must have prior experience performing the duties of a PSO during construction activity pursuant to a NMFS-issued incidental take authorization;

• PSOs must be approved by NMFS prior to beginning any activity subject to the IHA.
  PSOs should 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.
  For all pile driving activities, the USCG must establish the monitoring locations as described in the Monitoring Plan. PSOs would be equipped with high quality binoculars for monitoring and 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.

Reporting

A draft marine mammal monitoring report will be submitted to NMFS within 90 days after the completion of pile driving and removal activities for each IHA, 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 will include an overall description of work completed, a narrative regarding marine mammal sightings, and associated PSO data sheets. Specifically, the report must include:

• Dates and times (begin and end) of all marine mammal monitoring;
• Construction activities occurring during each daily observation period, including the number and type of piles driven or removed and by what method (i.e., impact, vibratory, DTH) 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: ○ Name of PSO who sighted the animal(s) and PSO location and activity at the time of sighting;

○ Time of sighting;

○ 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;

○ Distance and bearing of each marine mammal observed relative to the pile being driven for each sighting (if pile driving was occurring at time of sighting);

○ Estimated number of animals (min/max/best estimate);

○ Estimated number of animals by cohort (adults, juveniles, neonates, group composition, sex class, etc.);

○ Animal's closest point of approach and estimated time spent within the harassment zone; and

○ Description of any marine mammal behavioral observations (e.g., observed behaviors such as feeding or traveling), including an assessment of behavioral responses thought to have resulted from the activity (e.g., no response or changes in behavioral state such as ceasing feeding, changing direction, flushing, or breaching);

• Number of marine mammals detected within the harassment zones 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 reports will constitute the final reports. 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 (PR.ITP.MonitoringReports@noaa.gov), NMFS, and to the Alaska Regional Stranding Coordinator as soon as feasible. If the death or injury was clearly caused by the specified activity, the USCG must immediately cease the specified activities until NMFS is able to review the circumstances of the ( printed page 16681) incident and determine what, if any, additional measures are appropriate to ensure compliance with the terms of the IHA. The USCG must not resume their activities until notified by NMFS. The report must include the following information:

• Time, date, and location (latitude/longitude) of the first discovery (and updated location information if known and applicable);
• Species identification (if known) or description of the animal(s) involved;
• Condition of the animal(s) (including carcass condition if the animal is dead);
• Observed behaviors of the animal(s), if alive;
• If available, photographs or video footage of the animal(s); and
• General circumstances under which the animal was discovered.

Negligible Impact Analysis and Determination

NMFS has defined negligible impact as an impact resulting from the specified activity that cannot be reasonably expected to, and is not reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival (50 CFR 216.103). A negligible impact finding is based on the lack of likely adverse effects on annual rates of recruitment or survival (i.e., population-level effects). An estimate of the number of takes alone is not enough information on which to base an impact determination. In addition to considering estimates of the number of marine mammals that might be “taken” through harassment, NMFS considers other factors, such as the likely nature of any impacts or responses (e.g., intensity, duration), the context of any impacts or responses (e.g., critical reproductive time or location, foraging impacts affecting energetics), as well as effects on habitat, and the likely effectiveness of the mitigation. We also assess the number, intensity, and context of estimated takes by evaluating this information relative to population status. Consistent with the 1989 preamble for NMFS' implementing regulations (54 FR 40338, September 29, 1989), the impacts from other past and ongoing anthropogenic activities are incorporated into this analysis via their impacts on the baseline (e.g., as reflected in the regulatory status of the species, population size and growth rate where known, ongoing sources of human-caused mortality, or ambient noise levels).

To avoid repetition, the discussion of our analysis applies to all the species listed in table 8, given that the anticipated effects of this activity on these different marine mammal stocks are expected to be similar. There is little information about the nature or severity of the impacts, or the size, status, or structure of any of these species or stocks that would lead to a different analysis for this activity.

Pile driving and DTH activities associated with the specified activities, as described previously, have the potential to disturb or displace marine mammals. Specifically, the specified activities may result in take in the form of Level A and/or Level B harassment from underwater sounds generated from pile driving and DTH. Potential takes could occur if individual marine mammals are present in the ensonified areas above the thresholds for Level A harassment or Level B harassment identified in table 6 when pile driving or DTH is occurring.

No serious injury or mortality would be expected, even in the absence of required mitigation measures, given the nature of the activities. For humpback, gray, minke, and killer whales (LF and HF cetaceans), no Level A harassment is anticipated or proposed for authorization due to the confined nature of the facility, ability to position PSOs at stations from which they can observe the shutdown zones, and the high visibility of these species. The potential for harassment will be minimized through the construction method and the implementation of the proposed mitigation measures (see Proposed Mitigation section).

Take by Level A harassment is proposed for authorization for Steller sea lion, harbor seal, harbor porpoise, and Dall's porpoise. NMFS considers it unlikely that any individual would stay underwater within the calculated Level A harassment isopleth for the entire duration of a day of pile driving due to the general transient nature of cetaceans in the habitat, and the ability of pinnipeds to haul out on rocks and other structures. However, due to their relatively small sizes and typically cryptic behaviors, it is possible individuals of these species could enter the Level A harassment zone undetected and remain within that zone for a duration long enough to incur AUD INJ. Any take by Level A harassment is expected to arise from, at most, a small degree of AUD INJ (i.e., minor degradation of hearing capabilities within regions of hearing that align most completely with the energy produced by impact pile driving such as 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 more than a small degree of AUD INJ.

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 for authorization;
• Level A harassment would be very small amounts and of low degree;
• Level B harassment would be primarily in the form of behavioral disturbance, resulting in avoidance of the project area around where piling is occurring, with some low-level TTS that may limit the detection of acoustic cues for relatively brief amounts of time in the relatively confined footprint of the activity;
• The ensonified area is very small relative to the overall habitat ranges of all species and stocks, and would not adversely affect ESA-designated critical habitat for any species or any areas of known biological importance;
• The amount of take proposed for authorization accounts for no more than, at most, 4 percent of any stock that may occur in the project area;
• The lack of anticipated significant or long-term negative effects to marine mammal habitat; and
• The implementation of mitigation measures to minimize the number of marine mammals exposed to injurious levels of sound and ensure take by Level A harassment is, at most, a small degree of AUD INJ. Based on the analysis contained herein of the likely effects of the specified activity on marine mammals and their habitat, and taking into consideration the implementation of the proposed monitoring and mitigation measures, NMFS preliminarily finds that the total marine mammal take from the proposed activity will have a negligible impact on all affected marine mammal species or stocks.

Small Numbers

As noted previously, only take of small numbers of marine mammals may be authorized under section 101(a)(5)(A) and (D) of the MMPA for specified activities other than military readiness activities. The MMPA does not define small numbers and so, in practice, where estimated numbers are available, NMFS compares the number of individuals taken to the most appropriate estimation of abundance of the relevant species or stock in our ( printed page 16682) 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 (see 86 FR 5322, January 19, 2021). Additionally, other qualitative factors may be considered in the analysis, such as the temporal or spatial scale of the activities.

The amount of take NMFS proposes to authorize is below one-third of the estimated stock abundance of all species and stocks (take of individuals is less than 4 percent of the abundance of all affected stocks). This is likely a conservative estimate because it assumes all takes are of different individual animals, which is likely not the case. Some individuals may return multiple times in a day but PSOs would count them as separate takes if they cannot be individually identified.

There are no valid abundance estimates available for humpback whales (Mexico-North Pacific stock), minke whales (Alaska stock), Dall's porpoises (Alaska stock), and harbor porpoises (Yakutat/Southeast Alaska Offshore Waters stock). The best available information for each of these stocks is summarized below.

There is no recent stock abundance estimate for the Mexico-North Pacific stock of humpback whale and the minimum population is considered unknown (Young et al., 2024). There are two minimum population estimates for this stock that are over 15 years old: 2,241 (Martínez-Aguilar, 2011) and 766 (Wade, 2021). Using either of these estimates, the one take by Level B harassment proposed for authorization represents small numbers of the stock. There is also no current abundance estimate of the Alaska stock of minke whale, but over 2,000 individuals were documented in areas recently surveyed (Muto et al., 2021). Therefore, the 31 takes by Level B harassment represents small numbers of this stock, even if each take occurred to a new individual.

The most recent stock abundance estimate of the Alaska stock of Dall's porpoise was 83,400 animals and, although the estimate is more than 8 years old, it is unlikely this stock has drastically declined since that time. Therefore, the 46 takes proposed for authorization represent small numbers of this stock.

A current stock-wide abundance estimate for the Yakutat/Southeast Alaska Offshore Waters stock of harbor porpoises in offshore waters (which includes Moorings Sitka) is not available (Young et al., 2023). However, Muto et al. (2021) estimate the minimum stock size for the areas surveyed is 1,057 individuals. Therefore, the 76 takes proposed for authorization represent small numbers of this stock.

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

In order to issue an IHA, NMFS must find that the specified activity will not have an “unmitigable adverse impact” on the subsistence uses of the affected marine mammal species or stocks by Alaskan Natives. NMFS has defined “unmitigable adverse impact” in 50 CFR 216.103 as an impact resulting from the specified activity: (1) that is likely to reduce the availability of the species to a level insufficient for a harvest to meet subsistence needs by: (i) causing the marine mammals to abandon or avoid hunting areas; (ii) directly displacing subsistence users; or (iii) placing physical barriers between the marine mammals and the subsistence hunters; and (2) that cannot be sufficiently mitigated by other measures to increase the availability of marine mammals to allow subsistence needs to be met.

A description of “unmitigable adverse impact” on the subsistence uses of the affected marine mammal species or stocks by Alaskan Natives was included in the notice of proposed IHA (89 FR 60359, July 25, 2024) and the notice of the final IHA (89 FR 104090, December 20, 2024); since that time, we are not aware of any changes in the subsistence use of these species and stocks near Moorings Sitka. That information and analysis is referenced in this proposed IHA modification and is not repeated here; please refer to those notices.

Endangered Species Act

Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq.) requires that each Federal agency ensures that any action it authorizes, funds, or carries out is not likely to jeopardize the continued existence of any endangered or threatened species or result in the destruction or adverse modification of designated critical habitat. To ensure ESA compliance for the issuance of incidental take authorizations, NMFS consults internally whenever we propose to authorize take for ESA-listed species, in this case with the NMFS Alaska Regional Office.

There are two marine mammal species (Western DPS Steller sea lion and Mexico-North Pacific stock of humpback whale) with confirmed occurrence in the project area that are listed under the ESA. The NMFS Alaska Regional Office Protected Resources Division issued a Biological Opinion on December 3, 2024, under section 7 of the ESA, on the issuance of an IHA to the USCG under section 101(a)(5)(D) of the MMPA by the NMFS Permits and Conservation Division. The Biological Opinion concluded that the proposed action is not likely to jeopardize the continued existence of Western DPS Steller sea lion or Mexico DPS of humpback whale, and is not likely to destroy or adversely modify critical habitat for Western DPS Steller sea lion or Mexico DPS of humpback whale, as well as other ESA-listed species present at Moorings Seward (Western North Pacific DPS of humpback whale and Northeast Pacific stock of fin whale).

The Permits and Conservation Division has requested initiation of section 7 consultation with the Alaska Regional Office for the issuance of this modified IHA specific to the Sitka project area. NMFS will conclude the ESA consultation prior to reaching a determination regarding the proposed issuance of the authorization.

Proposed Authorization

As a result of these preliminary determinations, NMFS proposes to issue an IHA to the USCG for construction of a FRC homeporting dock in Sitka for a period of 1 year, provided the previously mentioned mitigation, monitoring, and reporting requirements are incorporated. A draft of the proposed IHA modification can be found at: https://www.fisheries.noaa.gov/​national/​marine-mammal-protection/​incidental-take-authorizations-construction-activities.

Request for Public Comments

We request comment on our analyses, the proposed authorization modification, and any other aspect of this notice of proposed IHA modification for the proposed construction project. Please include with your comments any supporting data or literature citations to help inform decisions on the request for this IHA modification.

( printed page 16683) Dated: March 30, 2026.

Kimberly Damon-Randall,

Director, Office of Protected Resources, National Marine Fisheries Service.

[FR Doc. 2026-06394 Filed 4-1-26; 8:45 am]

BILLING CODE 3510-22-P

Published Document: 2026-06394 (91 FR 16672)