Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Alaska LNG Project in Cook Inlet

FederalRegulations

Ask Donna

How this section applies to your facts.

Federal Register › Vol. 90 › 90 FR 35762

This text was captured on Aug 14, 2026. It is a snapshot, not a live feed, so check the official code before relying on it.

Text

ity of take;

• Requiring time/area closure for beluga whale during summer months in the western portion of Cook Inlet; and

• Requiring soft start for impact pile driving to allow marine mammals the opportunity to leave the area prior to beginning impact pile driving at full power.

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 216-6A, NMFS must review our proposed action ( i.e., promulgation of regulations and subsequent issuance of a 5-year LOA) with respect to potential impacts on the human environment.

NMFS participated as a cooperating agency on the 2020 Alaska LNG Project Environmental Impact Statement (EIS), which was finalized on March 6, 2020, and is available at https://www.ferc.gov/industries-data/natural-gas/environment/final-environmental-impact-statement-feis. When acting as a cooperating agency, as is the case with this project, NMFS may satisfy its independent NEPA obligations by either preparing a separate NEPA analysis for its issuance of an incidental take authorization or, if appropriate, by adopting the NEPA analysis prepared by the lead agency. NMFS independently reviewed and evaluated the 2020 Alaska LNG Project EIS and determined it was adequate and sufficient to meet our responsibilities under NEPA for the issuance of the 2020 Alaska LNG Cook Inlet LOA (85 FR 59291, September 21, 2020). NMFS therefore adopted the 2020 Alaska LNG Project EIS and signed a Record of Decision on February 16, 2021.

Consistent with NEPA, applicable NOAA NEPA procedures, and the information and analysis contained in this proposed rule, NMFS has made a preliminary determination that this proposed rule and any subsequent LOAs would not result in significant impacts that were not fully considered in the 2020 Alaska LNG Project EIS

outhward direction for approximately 26.7 miles (43 kilometers [km]), and cross the east Cook Inlet shoreline near Suneva Lake. An MOF (Mainline MOF) may be constructed on the west side of Cook Inlet near the existing Beluga Landing to support installation of the Cook Inlet shoreline crossing. See figure 1 for a map of 8 Star Alaska's action area (see 8 Star Alaska's application for color legends).

BILLING CODE 3510-22-P EP29JY25.004

BILLING CODE 3510-22-C Detailed Description of the Specified Activity

Construction of the Alaska LNG facilities would include construction of a Marine Terminal, comprised of a temporary marine terminal MOF and PLF; a Mainline MOF; and a pipeline (referred to as Mainline) crossing Cook Inlet. Noise generated by impact and vibratory pile driving would be likely to result in take of marine mammals. Additionally, we assume here that noise generated by AHTs conducting anchor handling may result in take of marine mammals.

Temporary Marine Terminal Material Offloading Facility

The temporary Marine Terminal MOF would consist of a quay and two berths, which would be used during construction of the Liquefaction Facility to enable direct deliveries of equipment modules, bulk materials, construction equipment, and other cargo to minimize the transport of large and heavy loads over road infrastructure. See Figure 6 in 8 Star Alaska's application for visual depiction of the Marine Terminal MOF. Construction of the Temporary MOF is expected to occur in Years 1 and 2.

Quay—The quay would be constructed of an outer wall consisting of combi-wall (combination of sheet pile and 66-inch steel pipe piles), tied back to a sheet pile anchor wall, and 11 sheet pile coffer cells, comprised of sheet piles and 24-inch pipe piles, backfilled with granular materials. The 24-inch pipe piles would be removed once coffer cell installation is complete. All pile installation and removal would be conducted with vibratory methods

ll consisting of combi-wall (combination of sheet pile and 66-inch steel pipe piles), tied back to a sheet pile anchor wall, and 11 sheet pile coffer cells, comprised of sheet piles and 24-inch pipe piles, backfilled with granular materials. The 24-inch pipe piles would be removed once coffer cell installation is complete. All pile installation and removal would be conducted with vibratory methods. 8 Star Alaska expects to use two crews during the installation of piles for the combi-wall and coffer cells, and therefore concurrent pile driving is expected to occur during installation of these features. This could result in concurrent vibratory pile driving of two 66-inch sheet piles, 2 sheet piles, 2 24-inch pile piles, a 66-inch pipe pile with a sheet pile, and a 24-inch pipe pile with a sheet pile. Installation of the sheet pile anchor wall is not considered in this analysis because the anchor wall would be installed into fill and would not generate substantial underwater sound.

Berths—Berths at the Marine Terminal MOF would include one Lift-on/Lift-off (Lo-Lo) berth and one Roll-on/Roll-off (Ro-Ro) berth maintained at depths alongside of 32 feet Mean Lower Low Water (MLLW). The berths would be constructed of 24-inch and 48-inch pipe piles using an impact hammer.

The Marine Terminal MOF would be constructed using both land-based (from shore and subsequently from constructed portions of the Marine Terminal MOF) and marine construction methods.

Dredging would be conducted at the Marine Terminal MOF with hydraulic or mechanical dredgers. While marine mammals may behaviorally respond in some small degree to the noise generated by dredging operations, given the slow, predictable movements of these vessels, and absent any other contextual features that would cause enhanced concern, NMFS does not consider it likely that 8 Star Alaska's proposed dredging would result in the take of marine mammals

kHz, which are above the range of marine mammals' hearing thresholds, and the magnetometer does not emit sound. Therefore, use of this equipment is not expected to result in take of marine

mammals, and it is not further evaluated in this proposed rule.

Nearshore Trenching, Pipelay, and Burial—In the nearshore portions of the route across Cook Inlet, the pipeline would be trenched and buried. The nearshore portion of the trench (extending from the shoreline to a transition water depth where a dredge vessel can be employed) would be constructed using amphibious or barge-based excavators. From the transition water depth to water depth of the −25 feet or −45 feet MLLW, 8 Star Alaska would use a dredge to excavate a trench for the pipeline. As described above, NMFS does not consider it likely that 8 Star Alaska's proposed dredging would result in the take of marine mammals.

Pipeline joints would be welded together onshore in 1,000 foot-long strings (pipe strings) and laid on the ground surface in an orientation that approximates the offshore alignment. 8 Star Alaska would anchor a pipe pull barge near the seaward end of the trench using AHTs. The barge would be used to pull the pipe strings from their onshore position into the trench. Given the transient and slow, predictable movement of barges, NMFS does not expect any potential for startle responses from individual marine mammals that may be in the vicinity. Similarly, with regard to the characteristics of noise output resulting from use of barges and other, similar industrial activities, NMFS generally assumes that the relative lack of variation in the signal and associated absence of high peak pressure or rapid rise time events (characteristics associated with impulsive and/or intermittent sound sources) significantly limits the likelihood of behavioral responses that might appropriately be considered take

4), NMFS anticipates that the AHTs would be rated between 4,000 horsepower (hp) and 8,000 hp. Potential tug power output during anchor handling is discussed in further detail in the Estimated Take of Marine Mammals section.

A summary of pile driving activities for the Alaska LNG facilities construction is provided in table 2, and a summary of the use of AHTs for pipelaying is provided in table 3.

Table 2—Anticipated In-Water Pile Driving Schedule Section Element Number of steel pipe piles or length of sheet piles 24-inch steel pipe 48-inch steel pipe 60-inch steel pipe 66-inch steel pipe Sheet piles Hammer type # days Year 1 Marine Terminal MOF Combi-wall 70 144 Vibratory 22 Marine Terminal MOF Coffer cell 48 1,496 Vibratory 56 Year 2 Marine Terminal MOF Coffer cell 40 1,491 Vibratory 54 Marine Terminal MOF Ro-Ro/Lo-Lo berths 7 28 Impact 14 Mainline MOF Quay 205 Vibratory/Impact 10 Mainline MOF Ro-Ro ramp 87 Vibratory/Impact 4 Year 3 PLF E-W Trestle 73 Impact 42 PLF Berth Loading Platforms 40 Impact 16 PLF N-S Trestle 40 Impact 16 Year 4 PLF E-W Trestle 28 Impact 14 PLF Operations Platform 12 Impact 6 PLF Breasting Dolphin 8 32 Impact 16 PLF Mooring Dolphin 2 8 Impact 4 PLF N-S Trestle 30 Impact 12 Year 5 PLF Mooring Dolphin 10 40 Impact 20 PLF Catwalk 8 Impact 16 Total 73 158 236 70 3,423 323 Table 3—Schedule of Anchor Handling for Construction of Mainline Across Cook Inlet Activity Hours/day Days Year 3 Nearshore pipelay 6 2 Year 4 Offshore pipelay 6 53 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

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. Alaska and Pacific SARs. All values presented in table 4 are the most recent available at the time of publication (including from the draft 2024 SARs) and are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

Table 4—Species 1 With Estimated Take From the Specified Activities 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 North Pacific -, -, N 26,960 (0.05, 25,849, 2016) 801 131 Family Balaenopteridae (rorquals) : Fin Whale Balaenoptera physalus Northeast Pacific E, D, Y 11,065 (0.405 7,970, 2013) 5 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 6 (N/A, N/A, 2006) UND 0.57 Humpback Whale Megaptera novaeangliae Western North Pacific E, D, Y 1,084 (0.088, 1,007, 2006) 3.4 5.82 Minke Whale Balaenoptera acutorostrata Alaska -, -, N N/A 7 (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

014,

Kendall et al., 2015). Gray whales are occasionally seen in mid- and upper Cook Inlet, Alaska, but they are not common. During NMFS aerial surveys conducted in June 1994, 2000, 2001, 2005, and 2009, gray whales were observed in Cook Inlet near Port Graham and Elizabeth Island as well as near Kamishak Bay, with one gray whale observed as far north as the Beluga River (Shelden et al., 2013). Gray whales were also observed offshore of Cape Starichkof in 2013 by marine mammal observers monitoring Buccaneer's Cosmopolitan drilling project (Owl Ridge, 2014) and in middle Cook Inlet in 2014 during the 2014 Apache 2D seismic survey (Lomac-MacNair et al., 2015). Several projects performed in Cook Inlet in recent years reported no observations of gray whales. These project activities included the SAExploration seismic survey in 2015 (Kendall and Cornick, 2015), the 2018 Cook Inlet Pipeline (CIPL) Extension Project (Sitkiewicz et al., 2018), and the 2019 Hilcorp seismic survey in lower Cook Inlet (Fairweather Science, 2020).

In 2020, during the aforementioned UME, a young male gray whale was stranded in the Twentymile River near Girdwood for over a week before swimming back into Turnagain Arm. The whale did not survive and was found dead in west Cook Inlet later that month (NMFS, 2020). One gray whale was sighted in Knik Arm near the Port of Alaska (POA) in Anchorage in upper Cook Inlet in May of 2020 during observations conducted during construction of the Petroleum and Cement Terminal project (61 North Environmental, 2021). The sighting occurred less than a week before the reports of the gray whale stranding in the Twentymile River and was likely the same animal. In 2021, one small gray whale was sighted in Knik Arm near Ship Creek, south of the POA (61 North Environmental, 2022a). Although some sightings have been documented in the middle and upper Inlet, the gray whale range typically only extends into the lower Cook Inlet region

curred less than a week before the reports of the gray whale stranding in the Twentymile River and was likely the same animal. In 2021, one small gray whale was sighted in Knik Arm near Ship Creek, south of the POA (61 North Environmental, 2022a). Although some sightings have been documented in the middle and upper Inlet, the gray whale range typically only extends into the lower Cook Inlet region.

Humpback Whale

The most comprehensive photo-identification data available suggest that approximately 89 percent of all humpback whales in the Gulf of Alaska are from the Hawaii stock, 11 percent are from the Mexico stock, and less than 1 percent are from the Western North Pacific stock (Wade, 2021). Individuals from different stocks are known to intermix in feeding grounds. There is no designated critical habitat for humpback whales in or near the area where the specified activity is planned to occur (86 FR 21082, April 21, 2021), nor does the project overlap with any known biologically important areas (Wild et al., 2023).

Humpback whales are encountered regularly in lower Cook Inlet and occasionally in mid-Cook Inlet; sightings are rare in upper Cook Inlet. Eighty-three groups containing an estimated 187 humpbacks were sighted during Cook Inlet beluga whale aerial surveys conducted by NMFS from 1994 to 2012 (Shelden et al., 2013). Surveys conducted north of the forelands have documented small numbers in middle Cook Inlet. During the 2014 Apache seismic surveys in Cook Inlet, five groups (six individuals) were reported, with three groups north of the forelands on the east side of the inlet (Lomac-MacNair et al., 2014). In 2015, during the construction of the Furie Operating Alaska, LLC (Furie) platform and pipeline, four groups of humpback whales were documented. Another group of 6 to 10 unidentified whales, thought to be either humpback or gray whales, was sighted approximately 15 km northeast of the Julius R

d, with three groups north of the forelands on the east side of the inlet (Lomac-MacNair et al., 2014). In 2015, during the construction of the Furie Operating Alaska, LLC (Furie) platform and pipeline, four groups of humpback whales were documented. Another group of 6 to 10 unidentified whales, thought to be either humpback or gray whales, was sighted approximately 15 km northeast of the Julius R. Platform Large cetaceans were visible near the project ( i.e., whales or blows were visible) for 2 hours out of the 1,275 hours of observation conducted (Jacobs Engineering Group Inc., 2015).

Minke Whale

No estimates have been made for the number of minke whales in the entire North Pacific (Young et al., 2024). However, some information is available on the number of minke whales in some areas of Alaska. Visual surveys for cetaceans were conducted on the eastern Bering Sea shelf in 2002, 2008, and 2010 in cooperation with research on commercial fisheries (Friday et al., 2013). Results of the surveys in 2002, 2008, and 2010 provided provisional abundance estimates of 389 (CV−0.52), 517 (CV = 0.69), and 2,020 (CV = 0.73) minke whales on the eastern Bering Sea shelf, respectively (Friday et al., 2013). These estimates are considered provisional because they have not been corrected for animals missed on the trackline, animals submerged when the ship passed, or responsive movement. Additionally, line transect surveys were conducted in shelf and nearshore waters (within 30-45 nautical miles of land) in 2001-2003 from the Kenai Fjords in the Gulf of Alaska to the central Aleutian Islands. Minke whale abundance was estimated to be 1,233 (CV = 0.34) for this area (Zerbini et al., 2006). This estimate has also not been corrected for animals missed on the trackline. The majority of the sightings were in the Aleutian Islands, rather than in the Gulf of Alaska, and in water shallower than 200 m

no minke whales were observed during observations conducted for the CIPL project near Tyonek (Sitkiewicz et al., 2018). Minke whales were also not recorded during Hilcorp's aerial or rig-based monitoring efforts in 2023 (Horsley and Larson, 2023).

Fin Whale

Fin whales' range extends into lower Cook Inlet; however, sightings are infrequent, and they are mostly spotted near the Inlet's entrance. Fin whales are usually observed as individuals traveling alone, although they are sometimes observed in small groups. From 2000 to 2022, 10 sightings of 26 estimated individual fin whales were observed in lower Cook Inlet during NMFS aerial surveys (Shelden et al., 2013, 2015b, 2017, 2022, Shelden and Wade, 2019). In the fall of 2019 during Hilcorp's seismic survey in lower Cook Inlet, 8 sightings of 23 fin whales were documented, suggesting greater numbers may use the area in the fall than previously estimated (Fairweather Science, 2020). Hilcorp did not record any sightings of fin whales from their aerial or rig-based monitoring efforts in 2023 (Horsley and Larson, 2023).

Beluga Whale

Five stocks of beluga whales are recognized in Alaska: the Beaufort Sea stock, eastern Chukchi Sea stock,

eastern Bering Sea stock, Bristol Bay stock, and Cook Inlet stock (Young et al., 2023). The Cook Inlet stock of beluga whale is the only stock that inhabits the project area. It is geographically and genetically isolated from the other stocks (O'Corry-Crowe et al., 1997, Laidre et al., 2000) and resides year-round in Cook Inlet (Laidre et al., 2000, Castellote et al., 2020). Cook Inlet beluga whales (CIBWs) were designated as depleted under the MMPA in 2000 (65 FR 34950, May 31, 2000), and as a distinct population segment (DPS) and listed as endangered under the ESA in October 2008 (73 FR 62919, October 10, 2008) when the species failed to recover following a moratorium on subsistence harvest. Between 2008 and 2018, CIBWs experienced a decline of about 2.3 percent per year (Wade et al., 2019)

(CIBWs) were designated as depleted under the MMPA in 2000 (65 FR 34950, May 31, 2000), and as a distinct population segment (DPS) and listed as endangered under the ESA in October 2008 (73 FR 62919, October 10, 2008) when the species failed to recover following a moratorium on subsistence harvest. Between 2008 and 2018, CIBWs experienced a decline of about 2.3 percent per year (Wade et al., 2019). The decline overlapped with the northeast Pacific marine heatwave that occurred from 2014 to 2016 in the Gulf of Alaska, significantly impacting the marine ecosystem (Suryan et al., 2021 as cited in Goetz et al., 2023).

In June 2023, NMFS released an updated abundance estimate for CIBWs in Alaska that incorporates aerial survey data from June 2021 and 2022 and accounted for visibility bias (Goetz et al., 2023). This report estimated that CIBW abundance is between 290 and 386, with a median best estimate of 331. Goetz et al. (2023) also present an analysis of population trends for the most recent 10-year period (2012-2022). The addition of data from the 2021 and 2022 survey years in the analysis resulted in a 65.1 percent probability that the CIBW population is now increasing at 0.9 percent per year (95 percent prediction interval of −3 to 5.7 percent). This increase drops slightly to 0.2 percent per year (95 percent prediction interval of −1.8 to 2.6 percent) with a 60 percent probability that the CIBW population is increasing more than 1 percent per year when data from 2021, which had limited survey coverage due to poor weather, are excluded from the analysis

Recovery Plan

In 2010, a recovery team, consisting of a science panel and stakeholder panel, began meeting to develop a recovery plan for the CIBW. The final recovery plan was published in the Federal Register on January 5, 2017 (82 FR 1325). In September 2022, NMFS completed the ESA 5-year review for the CIBW DPS and determined that the CIBW DPS should remain listed as endangered (NMFS, 2022a).

In its recovery plan (82 FR 1325, January 5, 2017), NMFS identified several potential threats to CIBWs, including: (1) high concern: catastrophic events ( e.g., natural disasters, spills, mass strandings), cumulative effects of multiple stressors, and noise; (2) medium concern: disease agents ( e.g., pathogens, parasites, and harmful algal blooms), habitat loss or degradation, reduction in prey, and unauthorized take; and (3) low concern: pollution, predation, and subsistence harvest. The recovery plan did not treat climate change as a distinct threat but rather as a consideration in the threats of high and medium concern. Other potential threats most likely to result in direct human-caused mortality or serious injury of this stock include vessel strikes.

Critical Habitat

On April 11, 2011, NMFS designated two areas of critical habitat for CIBW (76 FR 20179). The designation includes 7,800 square kilometers (km 2 ) of marine and estuarine habitat within Cook Inlet, encompassing approximately 1,909 km 2 in Area 1 and 5,891 km 2 in Area 2 (see figure 1 in 76 FR 20179). Area 1 of the CIBW critical habitat encompasses all marine waters of Cook Inlet north of a line connecting Point Possession (lat. 61.04° N, long. 150.37° W) and the mouth of Three Mile Creek (lat. 61.08.55° N, long. 151.04.40° W), including waters of the Susitna, Little Susitna, and Chickaloon Rivers below Mean Higher High Water (MHHW). From spring through fall, Area 1 critical habitat has the highest concentration of CIBWs due to its important foraging and calving habitat

cha ), and coho ( Oncorhynchus kisutch )), Pacific eulachon ( Thaleichthys pacificus ), Pacific cod ( Gadus macrocephalus ), walleye Pollock ( Gadus chalcogrammus ), saffron cod ( Eleginus gracilis ), and yellowfin sole ( Limanda aspera ) ;

(3) The absence of toxins or other agents of a type or amount harmful to CIBWs;

(4) Unrestricted passage within or between the critical habitat areas; and

(5) The absence of in-water noise at levels resulting in the abandonment of habitat by CIBWs.

Biologically Important Areas

Wild et al. (2023) delineated a small and resident population Biologically Important Area (BIA) in Cook Inlet that is active year-round and overlaps 8 Star Alaska's proposed project area. The authors assigned the BIA an importance score of 2, an intensity score of 2, a data support score of 3, and a boundary certainty score of 2 (scores range from 1 to 3, with a higher score representing an area of more concentrated or focused use and higher confidence in the data supporting the BIA (Harrison et al., 2023)). These scores indicate that the BIA is of moderate importance and intensity, the authors have high confidence that the population is small and resident and in the abundance and range estimates of the population, and the boundary certainty is medium (see Harrison et al. (2023) for additional information about the scoring process used to identify BIAs). The boundary of the CIBW BIA is consistent with NMFS' critical habitat designation (Wild et al., 2023).

Ecology

Generally, female beluga whales reach sexual maturity at 9 to 12 years old, while males reach maturity later (O'Corry‐Crowe, 2009); however, this can vary between populations. For example, in Greenland, males in a population of beluga whales were found to reach sexual maturity at 6 to 7 years of age and females at 4 to 7 years (Heide-Jørgensen and Teilmann, 1994)

e highest percent frequency of occurrence of prey species in CIBW stomachs. This suggests that their spring feeding in upper Cook Inlet, principally on fat-rich fish such as salmon and eulachon, is important to the energetics of these animals (NMFS, 2016).

The nutritional quality of Chinook salmon in particular is unparalleled, with an energy content four times greater than that of a Coho salmon. It is suggested the decline of the Chinook salmon population has left a nutritional void in the diet of the CIBWs that no other prey species can fill in terms of quality or quantity (Norman et al., 2022, Norman et al., 2020).

In fall, as anadromous fish runs begin to decline, CIBWs return to consume fish species (cod and bottom fish) found in nearshore bays and estuaries. Stomach samples from CIBWs are not available for winter (December through March), although dive data from CIBWs tagged with satellite transmitters suggest that they feed in deeper waters during winter (Hobbs et al., 2005), possibly on such prey species as flatfish, cod, sculpin, and pollock.

Distribution in Cook Inlet

The CIBW stock remains within Cook Inlet throughout the year, showing only small seasonal shifts in distribution (Goetz et al., 2012a, Lammers et al., 2013, Castellote et al., 2015, Shelden et al., 2015a, Shelden et al., 2018, Lowry et al., 2019). The ecological range of CIBWs has contracted significantly since the 1970s. From late spring to fall, nearly the entire population is now found in the upper inlet north of the forelands, with a range reduced to approximately 39 percent of the size documented in the late 1970s (Goetz et al., 2023). The recent annual and semiannual aerial surveys (since 2008) found that approximately 83 percent of the population inhabits the area between the Beluga River and Little Susitna River during the survey period, typically conducted in early June

nd in the upper inlet north of the forelands, with a range reduced to approximately 39 percent of the size documented in the late 1970s (Goetz et al., 2023). The recent annual and semiannual aerial surveys (since 2008) found that approximately 83 percent of the population inhabits the area between the Beluga River and Little Susitna River during the survey period, typically conducted in early June. Some aerial survey counts were performed in August, September, and October, finding minor differences in the numbers of belugas in the upper inlet compared to June, reinforcing the importance of the upper inlet habitat area (Young et al., 2023). 8 Star Alaska's proposed construction would not occur in this upper inlet habitat area.

During spring and summer, CIBWs generally aggregate near the warmer waters of river mouths along the northern shores of middle and upper Cook Inlet where prey availability is high and predator occurrence is low (Moore et al., 2000, Shelden and Wade, 2019, McGuire et al., 2020). In particular, CIBW groups are seen in the Susitna River Delta, the Beluga River and along the shore to the Little Susitna River, Knik Arm, and along the shores of Chickaloon Bay. Small groups were recorded farther south in Kachemak Bay, Redoubt Bay (Big River), and Trading Bay (McArthur River) prior to 1996, but rarely thereafter. Since the mid-1990s, most CIBWs (96 to 100 percent) aggregate in shallow areas near river mouths in upper Cook Inlet, and they are only occasionally sighted in the central or southern portions of Cook Inlet during summer (Hobbs et al., 2008). Almost the entire population can be found in northern Cook Inlet from late spring through the summer and into the fall (Muto et al., 2020), shifting into deeper waters in middle Cook Inlet in winter (Hobbs et al., 2008).

Data from tagged whales (14 tags deployed July 2000 through March 2003) show that CIBWs use upper Cook Inlet intensively between summer and late autumn (Hobbs et al., 2005)

such as the Susitna Delta (Beluga to Little Susitna Rivers) and Knik Arm, there was a high probability that CIBWs were in larger groups. CIBW presence and acoustic foraging behavior also increased closer to rivers with Chinook salmon runs, such as the Susitna River ( e.g., Castellote et al., 2021). Movement has been correlated with the peak discharge of seven major rivers emptying into Cook Inlet. Boat-based surveys from 2005 to the present (McGuire and Stephens, 2017) and results from passive acoustic monitoring across the entire inlet (Castellote et al., 2015) also support seasonal patterns observed with other methods. Based on long-term passive acoustic monitoring, foraging behavior was more prevalent during summer, particularly at upper inlet rivers, than during winter. The foraging index was highest at Little Susitna, with a peak in July-August and a secondary peak in May, followed by Beluga River and then Eagle Bay; monthly variation in the foraging index indicates CIBWs shift their foraging behavior among these three locations from April through September. The location of the towing routes are areas of predicted low density in the summer months.

CIBWs are believed to mostly calve in the summer, and breed between late spring and early summer (NMFS, 2016), primarily in upper Cook Inlet. The first neonates encountered during each field season from 2005 through 2015 were always seen in the Susitna River Delta in July. The photographic identification team's documentation of the dates of the first neonate of each year indicate that calving begins in mid-late July/early August, generally coinciding with the observed timing of annual maximum group size. Probable mating behavior of CIBWs was observed in April and May of 2014 in Trading Bay. Young CIBWs are nursed for 2 years and may continue to associate with their mothers for a considerable time thereafter (Colbeck et al., 2013). Important calving grounds are thought to be located near the river mouths of upper Cook Inlet

generally coinciding with the observed timing of annual maximum group size. Probable mating behavior of CIBWs was observed in April and May of 2014 in Trading Bay. Young CIBWs are nursed for 2 years and may continue to associate with their mothers for a considerable time thereafter (Colbeck et al., 2013). Important calving grounds are thought to be located near the river mouths of upper Cook Inlet.

During Apache's seismic test program in 2011 along the west coast of Redoubt Bay, lower Cook Inlet, a total of 33 CIBWs were sighted during the survey (Lomac-MacNair et al., 2013). During Apache's 2012 seismic program in mid-inlet, a total of 151 groups consisting of an estimated 1,463 CIBWs were observed (note individuals were likely observed more than once) (Lomac-MacNair et al., 2014). During SAExploration's 2015 seismic program, a total of 8 groups of 33 estimated individual CIBWs were visually observed during this time period and there were two acoustic detections of CIBWs (Kendall et al., 2015). During Harvest Alaska's recent CIPL project on the west side of Cook Inlet in between Ladd Landing and Tyonek Platform, a total of 143 CIBW groups (814 individuals) were observed almost daily from May 31 to July 11, even though observations spanned from May 9 through September 15 (Sitkiewicz et al., 2018). There were two CIBW carcasses observed by the project vessels in the 2019 Hilcorp lower Cook Inlet seismic survey in the fall which were reported to the NMFS Marine Mammal Stranding Network (Fairweather Science, 2020). Both carcasses were moderately decomposed when they were sighted by the PSOs. Daily aerial surveys specifically for CIBWs were flown over the lower Cook Inlet region, but no beluga whales were observed. In 2023, Hilcorp recorded 21 groups of more than 125 beluga whales during aerial surveys in middle Cook Inlet, and an additional 21 opportunistic groups which included approximately 81 CIBWs (Horsley and Larson, 2023)

t encountered within Knik Arm (Castellote et al., 2016). These detections were likely resident killer whales. Transient killer whales likely have not been acoustically detected due to their propensity to move quietly through waters to track prey (Small, 2010, Lammers et al., 2013). Transient killer whales were increasingly reported to feed on belugas in the middle and upper Cook Inlet in the 1990s.

During the 2015 SAExploration seismic program near the North Foreland, two killer whales were observed (Kendall et al., 2015, as cited in Weston and SLR, 2022). Killer whales were observed in lower Cook Inlet in 1994, 1997, 2001, 2005, 2010, 2012, and 2022 during the NMFS aerial surveys (Shelden et al., 2013, 2022). Eleven killer whale strandings have been reported in Turnagain Arm: 6 in May 1991 and 5 in August 1993. During the Hilcorp lower Cook Inlet seismic survey in the fall of 2019, 21 killer whales were documented (Fairweather Science, 2020). Throughout 4 months of observation in 2018 during the CIPL project in middle Cook Inlet, no killer whales were observed (Sitkiewicz et al., 2018). In September 2021, two killer

whales were documented in Knik Arm in upper Cook Inlet, near the POA (61 North Environmental, 2022a). Hilcorp did not record any sightings of killer whales from their aerial or rig-based monitoring efforts in 2023 (Horsley and Larson, 2023).

Pacific White-Sided Dolphin

The North Pacific stock of Pacific white-sided dolphin is common in the Gulf of Alaska's pelagic waters and Alaska's nearshore areas, British Columbia, and Washington Ferrero and Walker, 1996, as cited in Muto et al., 2022). They do not typically occur in Cook Inlet, but in 2019, Castellote et al. (2020) documented short durations of Pacific white-sided dolphin presence using passive acoustic recorders near Iniskin Bay (6 minutes) and at an offshore mooring located approximately midway between Port Graham and Iniskin Bay (51 minutes)

lheim et al., 2000). Harbor porpoises are often observed in lower Cook Inlet in Kachemak Bay and from Cape Douglas to the West Foreland (Rugh et al., 2005). They can be opportunistic foragers but consume primarily schooling forage fish (Bowen and Siniff, 1999). Subsistence users have not reported any harvest from the Gulf of Alaska harbor porpoise stock since the early 1900s (Shelden et al., 2014). Calving occurs from May to August; however, this can vary by region. Harbor porpoises often travel alone or in small groups of less than 10 individuals (Schmale, 2008).

Harbor porpoises occur throughout Cook Inlet, with passive acoustic detections being more prevalent in lower Cook Inlet. Although harbor porpoises have been frequently observed during aerial surveys in Cook Inlet (Shelden et al., 2014), most sightings are of single animals and are concentrated at Chinitna and Tuxedni bays on the west side of lower Cook Inlet (Rugh et al., 2005), with smaller numbers observed in upper Cook Inlet between April and October. The occurrence of larger numbers of porpoise in the lower Cook Inlet may be driven by greater availability of preferred prey and possibly less competition with CIBWs, as CIBWs move into upper inlet waters to forage on Pacific salmon during the summer months (Shelden et al., 2014).

An increase in harbor porpoise sightings in upper Cook Inlet was observed over recent decades ( e.g., 61 North Environmental, 2021, 2022a, Shelden et al., 2014). Small numbers of harbor porpoises have been consistently reported in upper Cook Inlet between April and October (Prevel-Ramos et al., 2008). The reason for the increase in sightings in upper Cook Inlet is unknown, although it may be an artifact of increased monitoring effort in upper Cook Inlet. It is also possible that the contraction in the CIBW's range has opened up previously occupied CIBW range to harbor porpoises (Shelden et al., 2014)

onsistently reported in upper Cook Inlet between April and October (Prevel-Ramos et al., 2008). The reason for the increase in sightings in upper Cook Inlet is unknown, although it may be an artifact of increased monitoring effort in upper Cook Inlet. It is also possible that the contraction in the CIBW's range has opened up previously occupied CIBW range to harbor porpoises (Shelden et al., 2014).

During Apache's 2012 seismic program in middle Cook Inlet, 137 groups of harbor porpoises comprising 190 individuals were documented between May and August (Lomac-MacNair et al., 2013). In June 2012, Shelden et al. (2015b) documented 65 groups of 129 individual harbor porpoises during an aerial survey, none of which were in upper Cook Inlet. Kendall et al. (2015, as cited in Weston and SLR, 2022) documented 52 groups comprising 65 individuals north of the Forelands during SAExploration's 2015 seismic survey. Shelden et al. (2017, 2019, 2022) also conducted aerial surveys in June and July over Cook Inlet in 2016, 2018, 2021, and 2022 and recorded 65 individuals. Observations occurred in middle and lower Cook Inlet with a majority in Kachemak Bay. There were two sightings of three harbor porpoises observed during the 2019 Hilcorp lower Cook Inlet seismic survey in the fall (Fairweather Science, 2020). A total of 29 groups (44 individuals) were observed north of the Forelands from May to September during the CIPL Extension Project (Sitkiewicz et al., 2018). During jack-up rig moves in 2021, a PSO observed two individual harbor porpoises in middle Cook Inlet: one in July and one in October. Four monitoring events were conducted at the POA in Anchorage between April 2020 and August 2022, during which 42 groups of harbor porpoises comprising 50 individual porpoises were documented over 285 days of observation (61 North Environmental, 2021, 2022a, 2022b, 2022c 2022c). One harbor porpoise was observed during Hilcorp's boat-based monitoring efforts in June 2023 (Horsley and Larson, 2023)

Four monitoring events were conducted at the POA in Anchorage between April 2020 and August 2022, during which 42 groups of harbor porpoises comprising 50 individual porpoises were documented over 285 days of observation (61 North Environmental, 2021, 2022a, 2022b, 2022c 2022c). One harbor porpoise was observed during Hilcorp's boat-based monitoring efforts in June 2023 (Horsley and Larson, 2023).

Dall's Porpoise

Dall's porpoises in Alaska are of the Alaska stock. This species can be found in offshore, inshore, and nearshore habitat. The most recently updated SAR for the Alaska stock of Dall's porpoise (Muto et al., 2021) assess the abundance of Alaska Dall's porpoise only in the northwestern Gulf of Alaska, which is a small portion of the stock's geographic range. Sighting surveys for cetaceans were conducted opportunistically during NMFS' pollock stock assessment surveys in 1999, 2000, 2002, 2004, 2008, and 2010 on the eastern Bering Sea shelf (Moore et al., 2002, Friday et al., 2012, 2013). The entire study area of the survey, which corresponded to only a fraction of the range of the Alaska stock, was fully covered in three of those years (2002, 2008, and 2010). Dall's porpoise abundance estimates were 35,303 (CV = 0.53) in 2002, 14,543 (CV = 0.32) in 2008, and 11,143 (CV = 0.32) in 2010 (Friday et al. 2013). Abundance estimates for Dall's porpoise in inland waters of Southeast Alaska were calculated from 19 line-transect vessel surveys from 1991 to 2012 (Jefferson et al. 2019). Abundance across the whole period was estimated at 5,381 (CV = 0.25), 2,680 (CV = 0.20), and 1,637 (CV = 0.23) in the spring, summer, and fall, respectively (Jefferson et al. 2019). Vessel surveys were carried out in and around a Navy Maritime Activity/Training Area in the northwestern Gulf of Alaska to document abundance and density of cetaceans in 2013 and 2015 (Rone et al. 2017)

s of three Dall's porpoises were observed in upper and middle Cook Inlet (Lomac-MacNair et al., 2014). In August 2015, one Dall's porpoise was reported in north of Nikiski in middle Cook Inlet during SAExploration's seismic program (Kendall et al., 2015). During aerial surveys in Cook Inlet, they were observed in Iniskin Bay, Barren Island, Elizabeth Island, and Kamishak Bay (Shelden et al., 2013). No Dall's porpoises were observed during the 2018 CIPL Extension Project Acoustic Monitoring Program in middle Cook Inlet (Sitkiewicz et al., 2018); however, 30 individuals in 10 groups were sighted during a lower Cook Inlet seismic project in the fall 2019 (Fairweather Science, 2020). Hilcorp recorded three sightings of Dall's porpoises in 2021 and one sighting of a Dall's porpoise in 2023 from their rig-based monitoring efforts in the project area (Korsmo et al., 2022, Horsley and Larson, 2023). One Dall's porpoise was observed near the POA during the NES1 project, but it is possible this was misidentified (61 North Environmental, 2025). This higher number of sightings suggests Dall's porpoise may use portions of middle Cook Inlet in greater numbers than previously expected but would still be considered infrequent in middle and upper Cook Inlet.

Steller Sea Lion

Two DPSs of Steller sea lion occur in Alaska: the western DPS and the eastern DPS. The western DPS includes animals that occur west of Cape Suckling, Alaska, and therefore includes individuals within the project area. The western DPS was listed under the ESA as threatened in 1990 (55 FR 49204, November 26, 1990), and its continued population decline resulted in a change in listing status to endangered in 1997 (62 FR 24345, May 5, 1997). Since 2000, studies indicate that the population east of Samalga Pass ( i.e., east of the Aleutian Islands) has increased and is potentially stable (Young et al., 2023).

There is uncertainty regarding threats currently impeding the recovery of Steller sea lions, particularly in the Aleutian Islands

R, 2022), in middle Cook Inlet in 2018 (Sitkiewicz et al., 2018), in lower Cook Inlet in 2019 (Fairweather Science, 2020), and near the POA in Anchorage in 2020, 2021, and 2022 (61 North Environmental, 2021, 2022a, 2022b, and 2022c). During NMFS CIBW aerial surveys from 2000 to 2016, 39 sightings of 769 estimated individual Steller sea lions in lower Cook Inlet were recorded (Shelden et al., 2017). Sightings of large congregations of Steller sea lions during NMFS aerial surveys occurred outside the specific geographic region, on land in the mouth of Cook Inlet ( e.g., Elizabeth and Shaw Islands). In 2012, during Apache's 3D Seismic surveys, three sightings of approximately four individuals in upper Cook Inlet were recorded (Lomac-MacNair et al., 2013). PSOs associated with Buccaneer's drilling project off Cape Starichkof observed seven Steller sea lions in summer 2013 (Owl Ridge, 2014), and another four Steller sea lions were observed in 2015 in Cook Inlet during SAExploration's 3D Seismic Program. Of the three 2015 sightings, one sighting occurred between the West and East Forelands, one occurred near Nikiski, and one occurred northeast of the North Foreland in the center of Cook Inlet (Kendall and Cornick, 2015). Five sightings of five Steller sea lions were recorded during Hilcorp's lower Cook Inlet seismic survey in the fall of 2019 (Fairweather Science, 2020). Additionally, one sighting of two individuals occurred during the CIPL Extension Project in 2018 in middle Cook Inlet (Sitkiewicz et al., 2018). At the end of July 2022, while conducting a waterfowl survey an estimated 25 Steller sea lions were observed hauled-out at low tide in the Lewis River, on the west side of Cook Inlet. (K. Lindberg, personal communication, August 15, 2022). Steller sea lions have also been reported near the POA in Anchorage in 2020, 2021, and 2022 (61 North Environmental 2021, 2022a, 2022b, and 2022c)

t al., 2018). At the end of July 2022, while conducting a waterfowl survey an estimated 25 Steller sea lions were observed hauled-out at low tide in the Lewis River, on the west side of Cook Inlet. (K. Lindberg, personal communication, August 15, 2022). Steller sea lions have also been reported near the POA in Anchorage in 2020, 2021, and 2022 (61 North Environmental 2021, 2022a, 2022b, and 2022c). Hilcorp did not record any sightings of Steller sea lions from their aerial or rig-based monitoring efforts in 2023 (Horsley and Larson, 2023).

Harbor Seal

Harbor seals in the proposed project area are of the Cook Inlet/Shelikof stock, which ranges from the southwest tip of

Unimak Island east along the southern coast of the Alaska Peninsula to Elizabeth Island off the southwest tip of the Kenai Peninsula, including Cook Inlet, Knik Arm, and Turnagain Arm. Distribution of the Cook Inlet/Shelikof stock extends from Unimak Island, in the Aleutian Islands archipelago, north through all of upper and lower Cook Inlet (Young et al., 2023).

Harbor seals inhabit the coastal and estuarine waters of Cook Inlet and occur in both upper and lower Cook Inlet throughout most of the year (Boveng et al., 2012, Shelden et al., 2013). High-density areas include Kachemak Bay, Iniskin Bay, Iliamna Bay, Kamishak Bay, Cape Douglas, and Shelikof Strait. Up to a few hundred seals seasonally occur in middle and upper Cook Inlet (Rugh et al. 2005), with the highest concentrations found near the Susitna River and other tributaries within upper Cook Inlet during eulachon and salmon runs (Nemeth et al., 2007; Boveng et al., 2012), but most remain south of the forelands (Boveng et al., 2012).

The results of past and recent satellite tagging studies in Southeast Alaska, Prince William Sound, Kodiak Island, and Cook Inlet are also consistent with the conclusion that harbor seals are non-migratory (Lowry et al., 2001; Small et al., 2003; Boveng et al., 2012)

ent research on satellite-tagged harbor seals observed several movement patterns within Cook Inlet (Boveng et al., 2012), including a strong seasonal pattern of more coastal and restricted spatial use during the spring and summer (breeding, pupping, molting) and more wide-ranging movements within and outside of Cook Inlet during the winter months, with some seals ranging as far as Shumagin Islands. During summer months, movements and distribution were mostly confined to the west side of Cook Inlet and Kachemak Bay, and seals captured in lower Cook Inlet generally exhibited site fidelity by remaining south of the Forelands in lower Cook Inlet after release (Boveng et al., 2012). In the fall, a portion of the harbor seals appeared to move out of Cook Inlet and into Shelikof Strait, northern Kodiak Island, and coastal habitats of the Alaska Peninsula. The western coast of Cook Inlet had higher usage by harbor seals than eastern coast habitats, and seals captured in lower Cook Inlet generally exhibited site fidelity by remaining south of the Forelands in lower Cook Inlet after release (south of Nikiski; Boveng et al., 2012).

Harbor seals have been sighted in Cook Inlet during every year of the aerial surveys conducted by NMFS and during recent mitigation and monitoring programs in lower, middle, and upper Cook Inlet (61N Environmental, 2021, 2022a, 2022b, and 2022c; Fairweather Science, 2020; Kendall et al., 2015 as cited in Weston and SLR, 2022; Lomac-MacNair et al., 2013, 2014; Sitkiewicz et al., 2018).

California Sea Lion

Few observations of California sea lions have been reported in Alaska, and most observations have been limited to solitary individuals, typically males that are known to migrate long distances. Occasionally, California sea lions occur in small groups of two or more, usually associated with Steller sea lions at their haul outs and rookeries (Maniscalco et al., 2004)

alized hearing ranges of all marine mammal hearing groups have been recently updated (NMFS, 2024) as reflected below in table 5.

Table 5—Marine Mammal Hearing Groups [NMFS, 2024] Hearing group Generalized hearing range * Low-frequency (LF) cetaceans (baleen whales) 7 Hz (Hertz) 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

on.

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 the likely impacts of these activities on the reproductive success or survivorship of individuals and whether those impacts are reasonably expected to, or reasonably likely to, adversely affect the species or stock through effects on annual rates of recruitment or survival.

Description of Sound Sources

The marine soundscape is comprised of both ambient and anthropogenic sounds. Ambient sound is defined as the all-encompassing sound in a given place and is usually a composite of sound from many sources both near and far. 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

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.

The proposed project includes impact and vibratory pile driving and use of AHTs to handle anchors during pipelaying. Impact hammers typically operate by repeatedly dropping and/or pushing a heavy piston onto a pile to drive the pile into the substrate. Sound generated by impact hammers is impulsive, characterized by rapid rise times and high peak levels, a potentially injurious combination (Hastings and Popper, 2005). Vibratory hammers install piles by vibrating them and allowing the weight of the hammer to push them into the sediment. Vibratory pile driving produces non-impulsive sound. Non-impulsive sounds typically do not have the high peak sound pressure with rapid rise/decay time that impulsive sounds do (ANSI, 1995, National Institute for Occupational Safety and Health (NIOSH), 1998, NMFS, 2024, ANSI, 2005). 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 piles (Oestman et al., 2009)

ve vs. non-impulsive), the species, age and sex class ( e.g., adult male vs. mom with calf), duration of exposure, the distance between the pile and the animal, received levels, behavior at time of exposure, and previous history with exposure (Wartzok et al., 2004, Southall et al., 2007). Here we discuss physical auditory effects (TS) 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). The amount of TS is customarily expressed in dB. TS can be permanent or temporary. As described by NMFS (2024), there are numerous factors to consider when examining the consequence of TS, including, but not limited to, the signal temporal pattern ( e.g., impulsive or non-impulsive), likelihood an individual would be exposed for a long enough duration or

to a high enough level to induce a TS, the magnitude of the TS, time to recovery (seconds to minutes or hours to days), the frequency range of the exposure ( i.e., spectral content), the hearing and vocalization frequency range of the exposed species relative to the signal's frequency spectrum ( i.e., how an animal uses sound within the frequency band of the signal ( e.g., Kastelein et al., 2014), and the overlap between the animal and the source ( e.g., spatial, temporal, and spectral).

Auditory Injury (AUD INJ) and Permanent Threshold Shift (PTS)

ermanent Threshold Shift (PTS)

NMFS defines auditory injury as “damage to the inner ear that can result in destruction of 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 Ahroon et al., 1996, Kryter et a l., 1966, Miller, 1974, Ward et al., 1958, 1959, Ward, 1960, Henderson et al., 2008). PTS levels for marine mammals are estimates because there are limited empirical data measuring PTS in marine mammals ( e.g., Kastak et al., 2008), 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.

Temporary Threshold Shift (TTS)

NMFS defines TTS as 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 (see Southall et al., 2007, 2019), a TTS of 6 dB is considered the minimum TS clearly larger than any day-to-day or session-to-session variation in a subject's normal hearing ability (Finneran et al., 2000, 2022, Schlundt et al., 2000). 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

sion-to-session variation in a subject's normal hearing ability (Finneran et al., 2000, 2022, Schlundt et al., 2000). 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 auditory masking, below). For example, a marine mammal may be able to readily compensate for a brief, relatively small amount of TTS in a non-critical frequency range that takes place during a time when the animal is traveling through the open ocean, where ambient noise is lower and there are not as many competing sounds present. Alternatively, a larger amount and longer duration of TTS sustained during 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.

to some degree, though likely not without cost.

Many studies have examined noise-induced hearing loss in marine mammals (see Finneran (2015) and Southall et al., (2019) for summaries). TTS is the mildest form of hearing impairment that can occur during exposure to sound (Kryter, 2013). While experiencing TTS, the hearing threshold rises, and a sound must be at a higher level in order to be heard. In terrestrial and marine mammals, TTS can last from minutes or hours to days (in cases of strong TTS). In many cases, hearing sensitivity recovers rapidly after exposure to the sound ends. For cetaceans, published data on the onset of TTS are limited to captive bottlenose dolphin ( Tursiops truncatus ), beluga whale, harbor porpoise, and Yangtze finless porpoise ( Neophocoena asiaeorientalis ) (Southall et al., 2019). For pinnipeds in water, measurements of TTS are limited to harbor seals, elephant seals ( Mirounga angustirostris ), bearded seals ( Erignathus barbatus ) and California sea lions (Kastak et al., 1999, Southall et al., 2007, Kastelein et al., 2019b, 2019c, 2021, 2022a, 2022b, Reichmuth et al., 2019, Sills et al., 2020). TTS was not observed in spotted ( Phoca largha ) and ringed ( Pusa hispida ) seals exposed to single airgun impulse sounds at levels matching previous predictions of TTS onset (Reichmuth et al., 2016). These studies examine hearing thresholds measured in marine mammals before and after exposure to intense or long-duration sound exposures. The difference between the pre-exposure and post-exposure thresholds can be used to determine the amount of threshold shift at various post-exposure times.

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., 2020a, Kastelein et al., 2020b, Kastelein et al., 2019a, Kastelein et al., 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 (Finneran et al., 2010, Kastelein et al., 2015, Kastelein et al., 2014, Mooney et al., 2009). This means that TTS predictions based on the total, SELcum 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

er 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. However, such relationships are assumed to be similar to those in humans and other terrestrial mammals. PTS typically occurs at exposure levels at least several dB above that inducing mild TTS ( e.g., a 40-dB threshold shift approximates PTS onset (Kryter et al., 1966, Miller, 1974), while a 6-dB threshold shift approximates TTS onset (Southall et al., 2007, Southall et al., 2019)). Based on data from terrestrial mammals, a precautionary assumption is that the PTS thresholds for impulsive sounds (such as impact pile driving pulses as received close to the source) are at least 6 dB higher than the TTS threshold on a peak-pressure basis, and PTS 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

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.

8 Star Alaska proposes to conduct vibratory and impact pile driving activities and use AHTs to manage anchors during pipelaying. There would likely be pauses in activities during the day. Given these pauses and the fact that many marine mammals are likely to be moving through the ensonified area and not remaining for extended periods of time, the potential for TS declines.

Behavioral Harassment

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., Moberg, 2000, Selye, 1950). In many cases, an animal's first and sometimes most economical (in terms of energetic costs) response is behavioral avoidance of the potential stressor. Autonomic nervous system responses to stress typically involve changes in heart rate, blood pressure, and gastrointestinal activity. These responses have a relatively short duration and may or may not have a significant long-term effect on an animal's fitness.

Neuroendocrine stress responses often involve the hypothalamus-pituitary-adrenal system. Virtually all neuroendocrine functions that are affected by stress—including immune competence, reproduction, metabolism, and behavior—are regulated by pituitary hormones. Stress-induced changes in the secretion of pituitary hormones have been implicated in failed reproduction, altered metabolism, reduced immune competence, and behavioral disturbance ( e.g., Moberg, 1987, Blecha, 2000)

her stressors and their effects on marine mammals have also been reviewed (Romano et al., 2002b, Fair and Becker, 2000) 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 vessel traffic in the Bay of Fundy was associated with decreased stress in North Atlantic right whales. In addition, Lemos et al. (2022) observed a correlation between higher levels of fecal glucocorticoid metabolite concentrations (indicative of a stress response) and vessel traffic in gray whales. These and other studies lead to a reasonable expectation that some marine mammals will experience physiological stress responses upon exposure to acoustic stressors and that it is possible that some of these would be classified as distress. In addition, any animal experiencing TTS would likely also experience stress responses (National Research Council, 2005); however, distress would be an unlikely result of these proposed project activities based on observations of marine mammals during previous, similar projects in the area.

In consideration of the range of potential effects (AUD INJ to behavioral disturbance), we consider the potential exposure scenarios and context in which species would be exposed to pile driving and AHT noise. CIBWs may be present in low numbers during the work; therefore, some individuals may be reasonably expected to be exposed to elevated sound levels, including briefly those that exceed the Level B harassment threshold for continuous or impulsive noise. However, CIBWs would be expected to be transiting through the area, given this work is proposed primarily in middle Cook Inlet (as described in the Description of Marine Mammals in the Area of Specified Activities section), thereby limiting exposure duration, as belugas in the area would be expected to be headed to or from the concentrated foraging areas farther north near the Susitna Delta and Knik and Turnigan Arms

be expected to be transiting through the area, given this work is proposed primarily in middle Cook Inlet (as described in the Description of Marine Mammals in the Area of Specified Activities section), thereby limiting exposure duration, as belugas in the area would be expected to be headed to or from the concentrated foraging areas farther north near the Susitna Delta and Knik and Turnigan Arms. Similarly, humpback whales, fin whales, minke whales, gray whales, killer whales, California sea lion, and Steller sea lions would not be expected to remain in the area of the AHTs. Dall's porpoise, harbor porpoise, and harbor seal have been sighted with more regularity than many other species during oil and gas activities in Cook Inlet, but due to the transitory nature of these species, they would be unlikely to remain at any particular site for the full duration of the noise-producing activity. In fact, during Hilcorp's jack-up rig-based monitoring efforts in 2023, only one Dall's porpoise, two harbor seals, and one harbor porpoise were observed across four different sightings, and observations only lasted 1 to 5 minutes (Horsley and Larson, 2023). Because of this and the relatively low-intensity source levels, the likelihood of AUD INJ over the course of the AHT activities is considered discountable. Harbor seals may linger or haul-out in the area, but they are not known to do so in any large number or for extended periods of time. Here we find there would be a small potential for TTS during the use of AHTs for anchor handling but again, AUD INJ would not be likely due to the nature of the activity. Potential for AUD INJ and TTS due to pile driving is discussed further in the Estimated Take of Marine Mammals section

or haul-out in the area, but they are not known to do so in any large number or for extended periods of time. Here we find there would be a small potential for TTS during the use of AHTs for anchor handling but again, AUD INJ would not be likely due to the nature of the activity. Potential for AUD INJ and TTS due to pile driving is discussed further in the Estimated Take of Marine Mammals section.

Given most marine mammals would likely be transiting through the area, exposure would be expected to be brief but, in combination with the actual presence of the AHTs and pile driving, could result in animals shifting pathways around the work site ( e.g., avoidance), increasing speed or dive times, or cessation of vocalizations. The

likelihood of no more than a short-term, localized disturbance response is supported by data indicating belugas regularly pass by industrialized areas such as the Port of Anchorage; therefore, we would not expect abandonment of their transiting route or other disruptions of their behavioral patterns. We also anticipate some animals may respond with such mild reactions to the project that the response would not be detectable.

While in some cases marine mammals have exhibited little to no obviously detectable response to certain common or routine industrialized activity (Cornick and Pinney, 2011), we conservatively assume here that exposure to received levels of sound above the Level B harassment threshold during AHT anchor-handling operations, in conjunction with the nature of AHT operations ( e.g., difficult to maneuver, potential need to operate at night) means it is possible that take could occur over the total estimated period of activities.

Masking

possible that take could occur over the total estimated period of activities.

Masking

Sound can disrupt behavior through masking, or interfering 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). Masking occurs when the receipt of a sound is interfered with by another coincident sound at similar frequencies and at similar or higher intensity and may occur whether the sound is natural ( e.g., snapping shrimp, wind, waves, precipitation) or anthropogenic ( e.g., pile driving, shipping, sonar, seismic exploration) in origin. 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. Masking of natural sounds can result when human activities produce high levels of background sound at frequencies important to marine mammals. Conversely, if the background level of underwater sound is high ( e.g., on a day with strong wind and high waves), an anthropogenic sound source would not be detectable as far away as would be possible under quieter conditions and would itself be masked.

Airborne Acoustic Effects

Pinnipeds that occur near the project site could be exposed to airborne sounds associated with pile driving, depending on their distance from pile driving activities. Cetaceans are not expected to be exposed to airborne sounds that would result in harassment as defined under the MMPA.

There are no known pinniped haulouts near the noise producing project components

Airborne Acoustic Effects

There are no known pinniped haulouts near the noise producing project components. Therefore, it is unlikely that pinnipeds would be taken by exposure to in-air noise during construction. 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 likely previously have been “taken” because of exposure to underwater sound above the behavioral harassment thresholds, which are generally 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 are not proposing to authorize incidental take solely from exposure to airborne sound for pinnipeds, and airborne sound is not discussed further.

Marine Mammal Habitat Effects

8 Star Alaska's proposed activities could have localized, temporary impacts on marine mammal habitat, including prey, by increasing in-water sound pressure levels and, for pile driving, slightly decreasing water quality. Increased noise levels may affect acoustic habitat and adversely affect marine mammal prey in the vicinity of the project area. Elevated levels of underwater noise would ensonify the project areas where both fishes and mammals occur and could affect foraging success

ammal habitat, including prey, by increasing in-water sound pressure levels and, for pile driving, slightly decreasing water quality. Increased noise levels may affect acoustic habitat and adversely affect marine mammal prey in the vicinity of the project area. Elevated levels of underwater noise would ensonify the project areas where both fishes and mammals occur and could affect foraging success.

The total seafloor area likely impacted by the pile driving associated with the project would be relatively small compared to the available habitat in Cook Inlet. Avoidance by potential prey ( i.e., fish) of the immediate area due to the temporary loss of this foraging habitat would be 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.

Potential Effects on Prey

Sound may affect marine mammals through impacts on the abundance, behavior, or distribution of prey species ( e.g., crustaceans, cephalopods, fishes, zooplankton). Marine mammal prey varies by species, season, and location and, for some, is not well documented. Studies regarding the effects of noise on known marine mammal prey are described here. Key impacts to fishes may include behavioral responses, hearing damage, barotrauma (pressure-related injuries), and mortality.

Fishes utilize the soundscape and components of sound in their environment to perform important functions such as foraging, predator avoidance, mating, and spawning (Fay, 2009, Zelick et al., 1999). 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)

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). However, some studies have shown no or slight reaction to impulse sounds ( e.g., Peña et al., 2013, Wardle et al., 2001, Jorgenson and Gyselman, 2009).

SPLs of sufficient strength have been known to cause injury to fishes and fish mortality (Popper et al., 2014). However, in most fish species, hair cells in the ear continuously regenerate and loss of auditory function likely is restored when damaged cells are replaced with new cells. Halvorsen et al. (2012) showed that a TTS of 4 to 6 dB was recoverable within 24 hours for one species. Impacts would be most severe when the individual fish is close to the source and when the duration of exposure is long. Injury caused by barotrauma can range from slight to severe and can cause death, and is most likely for fish with swim bladders. Barotrauma injuries have been documented during controlled exposure to impact pile driving (Casper et al., 2013, Halvorsen et al., 2012).

For pile driving, the most likely impact to fishes at the project site would be temporary avoidance of the area, although alarmed responses, including an increase in swimming speed and changes in ventilation and heart rate, could occur. The duration of fish avoidance of this area or an alarm response after pile driving stops is unknown, but a rapid return to normal recruitment, distribution, and behavior is anticipated. In relation to AHT activities, fish have been observed to react when engine and propeller sounds exceed a certain level (Ona and Godø, 1990, Ona, 1988, Olsen, 1983). Avoidance reactions have been observed in fish, including cod and herring, when vessel sound levels were 110 to 130 dB re 1 μPa root-mean-squared (RMS) (Ona and Godø, 1990, Nakken, 1992, Olsen, 1979, Ona and Toresen, 1988)

nticipated. In relation to AHT activities, fish have been observed to react when engine and propeller sounds exceed a certain level (Ona and Godø, 1990, Ona, 1988, Olsen, 1983). Avoidance reactions have been observed in fish, including cod and herring, when vessel sound levels were 110 to 130 dB re 1 μPa root-mean-squared (RMS) (Ona and Godø, 1990, Nakken, 1992, Olsen, 1979, Ona and Toresen, 1988). Vessel sound source levels in the audible range for fish are typically 150 to 170 dB re 1 μPa per Hz (Richardson et al., 1995). The AHTs used during the specified activity could be expected to produce levels in this range when in transit. However, much of the tugging would be mobile during anchor handling, and the tugging noise that occurs during anchor handling would be temporary, similar to pile driving. Therefore, based upon the reports in the literature and the predicted sound levels from these vessels, some temporary avoidance by fish in the immediate area may occur.

In addition to fish, prey sources such as marine invertebrates could potentially be impacted by noise stressors as a result of the proposed activities. However, most marine invertebrates' ability to sense sounds is limited. Invertebrates appear to be able to detect sounds (Pumphrey, 1950, Frings and Frings, 1967) and are most sensitive to low-frequency sounds (Packard et al., 1990, Budelmann and Williamson, 1994, Lovell et al., 2005, Mooney et al., 2010). Data on response of invertebrates such as squid, another marine mammal prey species, to anthropogenic sound is more limited (de Soto, 2016, Solé et al., 2017). Data suggest that cephalopods are capable of sensing the particle motion of sounds and detect low frequencies up to 1-1.5 kHz, depending on the species (Kaifu et al., 2008, Hu et al., 2009, Mooney et al., 2010, Samson et al., 2014). Sole et al

onstrated that squid statocysts act as an accelerometer through which particle motion of the sound field can be detected (Budelmann, 1992). Auditory injuries (lesions occurring on the statocyst sensory hair cells) have been reported upon controlled exposure to low-frequency sounds, suggesting that cephalopods are particularly sensitive to low-frequency sound (André et al., 2011, Solé et al., 2013). Behavioral responses, such as inking and jetting, have also been reported upon exposure to low-frequency sound (McCauley et al., 2000, Samson et al., 2014). Squids, like most fish species, are likely more sensitive to low frequency sounds and may not perceive mid- and high-frequency sonars.

With regard to potential impacts on zooplankton, McCauley et al. (2017) found that exposure to airgun noise resulted in significant depletion for more than half the taxa present and that there were two to three times more dead zooplankton after airgun exposure compared with controls for all taxa, within 1 km (0.6 mi) of the airguns. However, the results of this study are inconsistent with a large body of research that generally finds limited spatial and temporal impacts to zooplankton as a result of exposure to airgun noise ( e.g., Dalen and Knutsen, 1987, Payne, 2004, Stanley et al., 2011). Most prior research on this topic, which has focused on relatively small spatial scales, has showed minimal effects ( e.g., Bolle et al., 2012, Booman et al., 1996, Kostyuchenko, 1973, Pearson et al., 1994, Saetre and Ona, 1996).

Notably, a more recent study produced results inconsistent with those of McCauley et al. (2017). Researchers conducted a field and laboratory study to assess if exposure to airgun noise affects mortality, predator escape response, or gene expression of the copepod Calanus finmarchicus (Fields et al., 2019). There were no sublethal effects on the escape performance or the sensory threshold needed to initiate an escape response at any of the distances from the airgun that were tested. Whereas McCauley et al

onducted a field and laboratory study to assess if exposure to airgun noise affects mortality, predator escape response, or gene expression of the copepod Calanus finmarchicus (Fields et al., 2019). There were no sublethal effects on the escape performance or the sensory threshold needed to initiate an escape response at any of the distances from the airgun that were tested. Whereas McCauley et al. (2017) reported an SEL of 156 dB at a range of 509-658 m (1,670-2,159 feet (ft)), with zooplankton mortality observed at that range, Fields et al. (2019) reported an SEL of 186 dB at a range of 25 m (82 ft), with no reported mortality at that distance.

In summary, given the relatively small areas potentially affected, the short duration of sound associated with individual pile driving events, and the temporary nature of the use of AHTs for anchor handling activities, any adverse effects from 8 Star Alaska's activities on any prey habitat or prey populations would be expected to be minor and temporary. The most likely impact to fishes at the project site would be temporary avoidance of the area. Any behavioral avoidance by fish of the disturbed area would still leave significantly large areas of fish and marine mammal foraging habitat in the nearby vicinity. Thus, we conclude that the specified activities would not be 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 would not be 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 under the rule, 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

ute to adverse impacts on their populations.

Estimated Take of Marine Mammals

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).

Proposed takes would primarily be by Level B harassment, as exposure to sound resulting from use of the acoustic sources ( i.e., pile driving and AHT activities) has the potential to result in disruption of behavioral patterns for individual marine mammals. We note here that given the slow, predictable, and generally straight path of tugs towing and positioning, the likelihood of a resulting disruption of marine mammal behavioral patterns that would qualify as harassment is considered relatively low. However, in consideration of the relatively louder sound produced by these tugs and the sensitive context present in Cook Inlet, NMFS cannot consider the likelihood of take to be discountable and here consider it to be sufficiently likely that quantified exposures above the generalized harassment threshold equate to take. Therefore, we have quantified the potential exposures from this activity, assumed that these exposures would equate to take, and analyzed the impacts of the assumed takes, which we propose for authorization

ays of activities. We note that while these factors can contribute to a basic calculation to provide an initial prediction of potential takes, additional information that can qualitatively inform take estimates is also sometimes available ( e.g., previous monitoring results or average group size). Below, we describe the factors considered here in more detail and present the proposed take estimates.

Acoustic Criteria

NMFS recommends the use of acoustic criteria that identify the received level of underwater sound above which exposed marine mammals would be reasonably expected to be behaviorally harassed (equated to Level B harassment) or to incur AUD INJ of some degree (equated to Level A harassment). 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, Southall et al., 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

and can be difficult to predict ( e.g., Southall et al., 2007, Southall et al., 2021, Ellison et al., 2012). Based on what the available science indicates and the practical need to use a threshold based on a metric that is both predictable and measurable for most activities, NMFS typically uses a generalized acoustic threshold based on received level to estimate the onset of behavioral harassment. NMFS generally predicts that marine mammals are likely to be behaviorally harassed in a manner considered to be Level B harassment when exposed to underwater anthropogenic noise above root-mean-squared pressure received levels (RMS SPL) of 120 dB (referenced to 1 micropascal (re 1 μPa)) for continuous ( e.g., vibratory pile driving, drilling) and above RMS SPL 160 dB re 1 μPa for non-explosive impulsive ( e.g., seismic airguns) or intermittent ( e.g., scientific sonar) sources. Generally speaking, Level B harassment take estimates based on these behavioral harassment thresholds are expected to include any likely takes by TTS as, in most cases, the likelihood of TTS occurs at distances from the source less than those at which behavioral harassment is likely. TTS of a sufficient degree can manifest as behavioral harassment, as reduced hearing sensitivity and the potential reduced opportunities to detect important signals (conspecific communication, predators, prey) may result in changes in behavior patterns that would not otherwise occur.

8 Star Alaska's proposed activity includes the use of continuous (vibratory pile driving and AHTs engaged in anchor handling) and impulsive (impact pile driving) sources, and therefore the RMS SPL thresholds of 120 and 160 dB re 1 μPa are applicable

ed Source Levels [All vibratory hammers] Concurrent pile driving scenarios Predicted RMS (dB re 1 μPa) at 10 m 66-inch Steel Pipe Pile × 2 173 66-inch Steel Pipe Pile with Sheet Pile 170 Sheet Pile × 2 163 24-inch Steel Pipe Pile with Sheet Pile 165 24-inch Steel Pipe Pile × 2 166 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 topography. The general formula for underwater TL is:

TL = B * Log10 (R 1 /R 2 ), Where: TL = transmission loss in dB; B = transmission loss coefficient; 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. Absent site-specific acoustical monitoring with differing measured transmission loss, a practical spreading value of 15 is used as the transmission loss coefficient in the above formula. Project and site-specific transmission loss data for 8 Star Alaska's project area in Cook Inlet are not available; therefore, the default coefficient of 15 is used to determine the distances to the Level A and Level B harassment thresholds for all pile driving. All Level B harassment isopleths are reported in table 10. However, as discussed in the Proposed Monitoring and Reporting section, 8 Star Alaska would conduct SSV for pile driving. Following the analysis of SSV results, 8 Star Alaska may propose revised estimated Level A and Level B harassment zones (for the purpose of monitoring and reporting) and adjusted shutdown zones accordingly for NMFS review and approval.

The ensonified area associated with Level A harassment is more technically challenging to predict due to the need to account for a duration component

ile driving. Following the analysis of SSV results, 8 Star Alaska may propose revised estimated Level A and Level B harassment zones (for the purpose of monitoring and reporting) and adjusted shutdown zones accordingly for NMFS review and approval.

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 the best way to estimate isopleth distances when more sophisticated modeling methods are not available or practical. For stationary sources such as impact and vibratory pile driving and AHTs engaged in anchor handling, 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 are provided in table 9, and the resulting estimated isopleths are reported in table 10

uch as impact and vibratory pile driving and AHTs engaged in anchor handling, 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 are provided in table 9, and the resulting estimated isopleths are reported in table 10.

Table 9—User Spreadsheet Input Parameters Used for Calculating Level A Harassment Isopleths [Source levels provided in Table 7] Pile Piles per day Strikes per pile Duration to drive pile (min) Weighting factor adjustment Impact Sheet Pile 30 1,000 N/A 2 24-inch Steel Pipe Pile 4 1,000 N/A 2 48-inch Steel Pipe Pile 3 1,000 N/A 2 60-inch Steel Pipe Pile 4 1,000 N/A 2 Vibratory Sheet Pile 30 N/A 15 2.5 24-inch Steel Pipe Pile 8 N/A 15 2.5 66-inch Steel Pipe Pile 7 N/A 15 2.5 Concurrent Pile Driving With Two Vibratory Hammers 66-inch Steel Pipe Pile × 2 1 N/A * 105 2.5 66-inch Steel Pipe Pile with Sheet Pile 1 N/A * 450 2.5 Sheet pile × 2 1 N/A * 450 2.5 24-inch Steel Pipe Pile with Sheet Pile 1 N/A * 450 2.5 24-inch Steel Pipe Pile × 2 1 N/A * 120 2.5 * This value represents the maximum duration of concurrent activity. Table 10—Calculated Distances to Level A and Level B Harassment Isopleths for Pile Driving Pile Level A harassment zone (m) LF cetacean HF cetacean VHF cetacean Phocids Otariids Level B harassment zone (m) Impact Sheet Pile 6,061 773 9,380 5,385 2,007 1,000 24-inch Steel Pipe Pile 998 127 1,545 887 331 1,000 48-inch Steel Pipe Pile 1,120 143 1,733 995 371 1,359 60-inch Steel Pipe Pile 3,408 435 5,274 3,028 1,120 2,154 Vibratory Sheet Pile 30 12 25 39 13 4,642 24-inch Steel Pipe Pile 20 8 16 26 9 7,356 66-inch Steel Pipe Pile 53 21 44 69 23 21,544 Concurrent Pile Driving With Two Vibratory Hammers 66-inch Steel Pipe Pile × 2 85 33 69 109 37 34,146 66-inch Steel Pipe Pile With Sheet Pile 141 54 115 181 61 21,544 Sheet Pile × 2 48 19 39 62 21 7,356 24-inch Steel Pipe Pile With Sheet Pile 32 12 26 41 14 11,65

timate the area of ensonification for AHTs engaged in anchor handling, where distance traveled per day is the linear distance that the AHTs would be expected to travel over the course of a day, and r is the radial distance of the Level B harassment isopleth (3.85 km). 8 Star Alaska estimates the pipelay rate to be 2,500 feet/day (0.762 km/day), so 0.762 km was used as the distance traveled per day.

Area of ensonification = (Distance traveled per day × 2r) + πr 2 Table 11—Calculated Level A and B Harassment Areas of Ensonification Pile Level A harassment areas of ensonification (km 2 ) LF cetacean HF cetacean VHF cetacean Phocids Otariids Level B harassment area of ensonification (km 2 ) Impact Sheet Pile 57.7 0.94 138.21 45.47 6.33 1.57 24-inch Steel Pipe Pile 1.56 0.03 3.75 1.24 0.17 1.57 48-inch Steel Pipe Pile 1.97 0.03 4.72 1.56 0.22 2.9 60-inch Steel Pipe Pile 18.24 0.3 43.69 14.4 2.0 7.29 Vibratory Sheet Pile 0.00 0.00 0.00 0.00 0.00 33.85 24-inch Steel Pipe Pile 0.00 0.00 0.00 0.00 0.00 24.89 66-inch Steel Pipe Pile 0.00 0.00 0.00 0.00 0.00 62.54 66-inch Steel Pipe Pile × 2 0.01 0.00 0.01 0.02 0.00 1,426.4 66-inch Steel Pipe Pile with Sheet Pile 0.03 0.00 0.02 0.05 0.01 722.5 Sheet Pile × 2 0.00 0.00 0.00 0.01 0.00 85 24-inch Steel Pipe Pile With Sheet Pile 0.01 0.00 0.00 0.01 0.00 157.08 24-inch Steel Pipe Pile × 2 0.00 0.00 0.00 0.00 0.00 213.5 AHTs Anchor Handling 0.00 0.00 0.00 0.01 0.00 52.4 Level A harassment zones are typically smaller than Level B harassment zones. However, in some cases, the calculated Level A harassment isopleth is greater than the calculated Level B harassment isopleth. Calculation of Level A harassment isopleths include a duration component, which in the case of impact pile driving, is estimated through the total number of daily strikes and the associated pulse duration. For a stationary sound source, we assume here that an animal is exposed to all of the strikes expected within a 24-hour period

sopleth is greater than the calculated Level B harassment isopleth. Calculation of Level A harassment isopleths include a duration component, which in the case of impact pile driving, is estimated through the total number of daily strikes and the associated pulse duration. For a stationary sound source, we assume here that an animal is exposed to all of the strikes expected within a 24-hour period. Calculation of

a Level B harassment zone does not include a duration component. Depending on the duration included in the calculation, the calculated Level A harassment isopleths can be larger than the calculated Level B harassment isopleth for the same activity.

Mainline Installation

8 Star Alaska intends to use AHTs to position a pipelaying barge in order to install the pipe on the seafloor for the Mainline across Cook Inlet. For the nearshore pipelay, planned for Year 3, an AHT would engage in anchor handling to moor a pull barge, and is expected to be used for two days of work, one day on the west coast near Beluga and one day on the east coast near Suneva Lake. For offshore pipelay, AHTs would be engaged in anchor handling to repeatedly position the barge during the duration of pipelay. Consistent with other tug activities, including those for tugs towing a jack-up rig (Furie Operating Alaska, LLC Natural Gas Activities, 89 FR 77836, September 24, 2024; Hilcorp Alaska, LLC, 89 FR 79529, September 30, 2024), NMFS anticipates that the AHTs would operate at approximately 50 percent power during anchor handling activities.

Because of the similarities to tugging activities planned by Hilcorp in Cook Inlet (89 FR 79529, September 30, 2024), NMFS determined it appropriate to adopt analysis provided for those activities for 8 Star Alaska's planned tugging activities. In addition, we refer here to an existing literature review of available source level data for tugs under load in varying power output scenarios (87 FR 27597, May 9, 2022). Please see that notice for the detailed analysis

rp in Cook Inlet (89 FR 79529, September 30, 2024), NMFS determined it appropriate to adopt analysis provided for those activities for 8 Star Alaska's planned tugging activities. In addition, we refer here to an existing literature review of available source level data for tugs under load in varying power output scenarios (87 FR 27597, May 9, 2022). Please see that notice for the detailed analysis. While that analysis is for tugs under load towing a jack-up rig, NMFS expects the AHT power output for the proposed anchor handling is to be consistent with that assumed for tugs towing a jack-up rig (Furie Operating Alaska, LLC Natural Gas Activities, 89 FR 77836, September 24, 2024; Hilcorp Alaska, LLC, 89 FR 79529, September 30, 2024), and therefore, NMFS determined that this analysis represents the best scientific evidence available for considering the appropriate source level proxy for 8 Star Alaska's proposed AHT use during anchor handling.

In addition to the literature review referenced above, which indicates that a source level of 180 dB for a single AHT would be appropriate, we also consider other relevant information to adequately consider 8 Star Alaska's planned use of three AHTs to handle anchors. If all three tugs were operating simultaneously at 180 dB RMS, the overall source emission levels would be expected to increase by approximately 5 dB when logarithmically adding the sources ( i.e., to 185 dB RMS). To further support this level as an appropriate proxy, a sound source verification (SSV) study performed by JASCO Applied Sciences (JASCO) in Cook Inlet in October 2021 (Lawrence et al., 2022) measured the sound source level from three tugs pulling a jack-up rig in Cook Inlet at various power outputs. Lawrence et al. (2022) reported a source level of 167.3 dB RMS for the 20 percent-power scenario and a source level of 205.9 dB RMS for the 85 percent-power scenario

pecies.

CIBW densities estimated from the AFSC surveys across regions are low; however, there is a known effect of seasonality on their distribution. Thus, densities derived directly from these summer surveys might underestimate the density of CIBWs in lower Cook Inlet at other ice-free times of the year. Therefore, NMFS used the Goetz et al. (2012a) habitat-based model to determine CIBW density. This model is derived from sightings and incorporates depth soundings, coastal substrate type, environmental sensitivity index, anthropogenic disturbance, and anadromous fish streams to predict densities throughout Cook Inlet. The output of this model is a density map of Cook Inlet, which predicts spatially explicit density estimates for CIBW. Using the resulting grid densities, average densities were calculated for three regions applicable to 8 Star Alaska's operations (table 13). The densities applicable to the area of activity ( i.e., the Marine Terminal near Nikiski, the Mainline in middle Cook Inlet, and the Mainline MOF near Tyonek) are provided in table 13 and were carried forward to the exposure estimates as they were deemed to be the most representative estimates available.

Although data exists for Steller sea lions and fin whales in Cook Inlet from AFSC aerial surveys, this data is based on sightings of Steller sea lions and fin whales that were mostly observed in lower Cook Inlet and is not representative of middle Cook Inlet, where 8 Star Alaska proposes to conduct construction. Therefore, in order to calculate take of these species, NMFS proposes to use marine mammal occurrence.

ook Inlet, where 8 Star Alaska proposes to conduct construction. Therefore, in order to calculate take of these species, NMFS proposes to use marine mammal occurrence.

For Steller sea lions, NMFS proposes to use monitoring data from the Port of Alaska (POA) in Anchorage, as these animals would be expected to pass through middle Cook Inlet and therefore be observed in 8 Star Alaska's Project Area. In 2020-2022 and 2024 (61 North Environmental, 2021, 2022a, 2022b, 2025, Easley-Appleyard and Leonard, 2022), the maximum number of Steller sea lions observed at POA was nine animals, eight during Petroleum and Cement Terminal (PCT) observations (61 North Environmental, 2022a) and one during NMFS 2021 monitoring effort (Easley-Appleyard and Leonard, 2022). Therefore, NMFS anticipates that up to nine Steller sea lions may occur in the project area per year during the course of 8 Star Alaska's proposed project.

During seismic surveys conducted in 2019 by Hilcorp in the lower Cook Inlet, fin whales were recorded in groups ranging in size from one to 15 individuals (Fairweather, 2020). During the NMFS aerial surveys in Cook Inlet from 2000 to 2018, 10 sightings of 26 estimated individual fin whales in lower Cook Inlet were observed (Shelden et al. 2013, 2015, 2016, 2019). Therefore, NMFS anticipates that one group of two fin whales (the lower end of the range of common group sizes) may occur in the project area per year during the course of 8 Star Alaska's proposed project.

No density estimates are available for Pacific white-sided dolphins and California sea lions, as they are so infrequently sighted. Therefore, NMFS proposes to authorize take of these species based on group number (see table 14).

Due to the paucity of data of Pacific white-sided dolphins in this region, there is no available density for Pacific white-sided dolphins

Fin whale 2 Pacific white-sided dolphin 3 California sea lion 2 Steller sea lion 9 * Marine mammal occurrence is used when density data is unavailable or not representative of the proposed project area. 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.

To estimate take by Level B harassment for all species except for fin whale, Pacific white-sided dolphin, California sea lion, and Steller sea lion, 8 Star Alaska multiplied the area (km 2 ) estimated to be ensonified above the Level B harassment thresholds (table 11) for each activity by the duration (days) of that activity by the calculated density for each species (number of animals/km 2 ). As described above, take of fin whale, Pacific white-sided dolphin, California sea lion, and Steller sea lion were calculated using group numbers and estimated frequency of occurrence (see table 14).

For species where calculated take by Level B harassment was less than the average group size for that species, NMFS rounded up the take estimate to the anticipated group size as displayed in table 15 and described below.

BILLING CODE 3510-22-P EP29JY25.005

EP29JY25.006

EP29JY25.007

EP29JY25.008

EP29JY25.009

BILLING CODE 3510-22-C During Apache's 2012 seismic program, nine sightings of a total of nine gray whales were observed in June and July (Lomac-MacNair et al., 2013). In 2014, one gray whale was observed during Apache's seismic program (Lomac-MacNair et al., 2014) and in 2015, no gray whales were observed during SAExploration's seismic survey (Kendall and Cornick, 2015). No gray whales were observed during the 2018 Cook Inlet Pipeline (CIPL) Extension Project (Sitkiewicz et al., 2018) or during the 2019 Hilcorp seismic survey in lower Cook Inlet (Fairweather Science, 2020)

gray whale was observed during Apache's seismic program (Lomac-MacNair et al., 2014) and in 2015, no gray whales were observed during SAExploration's seismic survey (Kendall and Cornick, 2015). No gray whales were observed during the 2018 Cook Inlet Pipeline (CIPL) Extension Project (Sitkiewicz et al., 2018) or during the 2019 Hilcorp seismic survey in lower Cook Inlet (Fairweather Science, 2020). The greatest densities of gray whales in Cook Inlet occur from November through January and March through May; the former are southbound, the latter are northbound (Ferguson et al., 2015). Based on this information, NMFS is proposing to authorize three takes by Level B harassment annually for gray whales. This is higher than the exposure estimate for each to allow for the potential occurrence of a group, or several individuals, per year.

During annual aerial surveys conducted in Cook Inlet from 2000 to 2016, humpback group sizes ranged from one to 12 individuals, with most groups comprised of 1 to 3 individuals (Shelden et al., 2013). Three humpback whales were observed in Cook Inlet during SAExploration's seismic study in 2015: two near the Forelands and one in Kachemak Bay (Kendall and Cornick, 2015). In total, 14 sightings of 38 humpback whales (ranging in group size from 1 to 14) were recorded in the 2019 Hilcorp lower Cook Inlet seismic survey in the fall (Fairweather Science, 2020). Two sightings totaling three individual humpback whales were recorded near Ladd Landing north of the Forelands on the recent Harvest Alaska CIPL Extension Project (Sitkiewicz et al., 2018). Based on documented observations from the CIPL Extension Project, which is the data closest to 8 Star Alaska's project area, NMFS is proposing to authorize three takes by Level B harassment for humpback whales for years 3 and 5. For years 1, 2, and 4, the calculated take exceeds the estimated group size

s (NMFS, 2025a). During seismic surveys conducted in 2019 by Hilcorp in lower Cook Inlet, Dall's porpoises were recorded in groups ranging from two to seven individuals (Fairweather Science, 2020). The 2012 Apache survey recorded two groups of three individual Dall's porpoises (Lomac-MacNair et al., 2014). NMFS

proposes to authorize six takes by Level B harassment per year for Dall's porpoises. This is greater than the estimated exposure estimate for each year, but would allow for at least one group at the higher end of documented group size or a combination of small groups.

8 Star Alaska proposes to shut down at the Level A harassment isopleth for all vibratory pile driving activities. The largest Level A harassment isopleth during vibratory pile driving is 181 m, and NMFS anticipates that 8 Star Alaska would be able to adequately monitor these zones and shutdown appropriately. NMFS, therefore, does not expect and does not propose to authorize Level A harassment due to vibratory pile driving for any species. As discussed in the Acoustic Impacts section, due to the characteristics of noise produced by AHTs, e.g., low-intensity source levels relative to impact pile driving, and transitory nature of occurrence of marine mammal species in this area, auditory injury is not a likely outcome of this activity. Therefore, NMFS does not expect, and does not propose to authorize, take by Level A harassment due to AHTs engaging in anchor handling.

ake by Level A harassment due to AHTs engaging in anchor handling.

To estimate take by Level A harassment from impact pile driving, 8 Star Alaska multiplied the area (km 2 ) estimated to be ensonified above the Level A harassment thresholds (table 11) for each impact pile driving activity by the duration (days) of that activity by the calculated density for each species (number of animals/km 2 ). Due to the infrequency of occurrence of fin whales, Pacific white-sided dolphins, California sea lions, and Steller sea lions in middle Cook Inlet, NMFS does not expect these species to enter Level A harassment zones for sufficient duration to incur injury, and is not proposing to authorize take by Level A harassment of these species.

When attributing take to respective humpback whale stocks for each year, NMFS assumed that 89 percent of calculated take would be from the Hawai'i stock, 10.7 percent would be from the Mexico-North Pacific stock, and 0.3 percent would be from the Western North Pacific stock, as described in Wade (2021) (see table 17). Although the number calculated for the Western North Pacific stock is less than 0.5 animals, NMFS is conservatively attributing one take by Level B harassment to the Western North Pacific stock of the humpback whale.

For species for which take by Level A harassment is anticipated, those estimated takes by Level A harassment were subtracted from the estimated takes by Level B harassment to avoid double-counting the same exposures as both Level A and Level B harassment. Adjustments are reflected in table 17.

BILLING CODE 3510-22-P EP29JY25.010

EP29JY25.011

EP29JY25.012

EP29JY25.013

EP29JY25.014

EP29JY25.015

s as both Level A and Level B harassment. Adjustments are reflected in table 17.

BILLING CODE 3510-22-P EP29JY25.010

EP29JY25.011

EP29JY25.012

EP29JY25.013

EP29JY25.014

EP29JY25.015

BILLING CODE 3510-22-C To inform both the negligible impact analysis and the small numbers determination, NMFS assesses the maximum number of takes of marine mammals that could occur within any given year. In this calculation, the maximum proposed number of Level A harassment takes in any one year is summed with the maximum proposed number of Level B harassment takes in any one year for each species to yield the highest number of estimated take that could occur in any year (table 18) for each stock. Table 18 also depicts the number of takes proposed relative to the abundance of each stock.

Table 18—Maximum Annual Take Proposed for Authorization and as a Percentage of Stock Abundance Species Stock NMFS stock abundance Maximum annual proposed Level A harassment Maximum annual proposed Level B harassment Maximum annual proposed take Maximum annual proposed take as a percentage of stock abundance Gray whale Eastern North Pacific 26,960 0 3 3 0.01 Fin whale Northeast Pacific UND 0 2 2 * N/A Humpback whale Hawai'i 11,278 2 56 58 0.58 Mexico-North Pacific N/A 0 6 6 * N/A Western North Pacific 1,084 0 1 1 0.09 Minke whale Alaska N/A 0 3 3 * N/A Killer whale Eastern North Pacific Alaska Resident 1,920 0 21 21 1.09 Eastern North Pacific Gulf of Alaska, Aleutian Islands, and Bering Sea Transient 587 3.58 Pacific white-sided dolphin North Pacific 26,880 0 3 3 0.01 CA/OR/WA 34,999 0.01 Beluga whale Cook Inlet 331 0 30 30 9.06 Dall's porpoise Alaska UND 0 6 6 * N/A Harbor porpoise Gulf of Alaska 31,046 8 128 136 0.44 California sea lion U.S 257,606 0 2 2 <0.01 Steller sea lion Western 49,837 0 9 9 0.02 Harbor seal Cook Inlet/Shelikof Strait 28,411 176 9,005 9,181 32.31 * See small numbers discussion below for additional information

h Pacific 26,880 0 3 3 0.01 CA/OR/WA 34,999 0.01 Beluga whale Cook Inlet 331 0 30 30 9.06 Dall's porpoise Alaska UND 0 6 6 * N/A Harbor porpoise Gulf of Alaska 31,046 8 128 136 0.44 California sea lion U.S 257,606 0 2 2 <0.01 Steller sea lion Western 49,837 0 9 9 0.02 Harbor seal Cook Inlet/Shelikof Strait 28,411 176 9,005 9,181 32.31 * See small numbers discussion below for additional information. Proposed Mitigation

In order to promulgate a rulemaking under section 101(a)(5)(A) of the MMPA, NMFS must set forth the permissible methods of taking pursuant to the activity and other means of effecting the least practicable adverse 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:

s where tugging operations occur during nighttime hours. In these circumstances, 8 Star Alaska would clear the clearance zones to the maximum extent possible.

Monitoring for Level A and Level B Harassment

8 Star Alaska would monitor for marine mammals in the Level B harassment and Level A harassment zones, to the extent practicable, and throughout the area as far as visual monitoring can occur. Monitoring enables observers to be aware of and communicate the presence of marine mammals in the project area outside the shutdown zone. Due to some of the large Level A and Level B harassment zones (table 10), PSOs would not be able to effectively observe the entire zones

during all activities for all species. All marine mammals observed within the visible portion of the harassment zones would be recorded. 8 Star Alaska would also conduct acoustic monitoring as described in the Proposed Monitoring and Reporting section below.

Soft Start

Soft-start procedures provide additional protection to marine mammals by providing warning and/or giving marine mammals a chance to leave the area prior to the hammer operating at full capacity. For impact pile driving, contractors would be required to provide an initial set of three strikes from the hammer at reduced energy, followed by a 30-second waiting period, then two subsequent three-strike sets before initiating continuous driving. Soft start would 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.

Vessel Transit

Operators of vessels would avoid approaching marine mammals within 100 yards (92 m). The vessel operator would avoid placing the vessel in the path of a whale and would not cut in front of the whale in a way or at a distance that causes the whale to change direction of travel or behavior (including breathing/surface pattern)

movement within the Susitna Delta Exclusion Zone. The vessel crew would report sightings to the PSO team for inclusion in the overall sighting database and reports.

• Vessel operators would not move their vessels when they are unable to adequately observe the 100-meter zone around vessels under power (in gear) due to darkness, fog, or other conditions, unless necessary for ensuring human safety.

The Susitna Delta Exclusion Zone (see figure 2) is defined as the union of the areas defined by:

(i) A 16-km (10-mile) buffer of the Beluga River thalweg seaward of the MLLW line;

(ii) A 16-km (10-mile) buffer of the Little Susitna River thalweg seaward of the MLLW line; and

(iii) A 16-km (10-mile) seaward buffer of the MLLW line between the Beluga River and Little Susitna River.

(iv) The buffer extends landward along the thalweg to include intertidal waters within rivers and streams up to their MHHW. The seaward boundary has been simplified so that it is defined by lines connecting readily discernable landmarks.

Time/Area Restriction

Pile driving associated with the Mainline MOF would not occur from June 1 to September 7.

Between April 15 and October 15, 8 Star Alaska would not conduct pile driving or AHT activities with Level B harassment isopleths that would extend shoreward of the MLLW line in the Susitna Delta (Beluga River to the Little Susitna River; see figure 2) and project vessel(s) operating in or transiting through Cook Inlet would maintain a distance of at least 1.5 nautical miles seaward of the MLLW line in the Susitna Delta (Beluga River to the Little Susitna River).

BILLING CODE 3510-22-P EP29JY25.016

BILLING CODE 3510-22-C Noise Attenuation

Each construction year, 8 Star Alaska proposes to use a noise attenuation device, such as a bubble curtain, and test it for effectiveness through Sound Source Verification (SSV) (see Proposed Monitoring section below) at the beginning of pile driving

e 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.

Visual Monitoring

Marine mammal monitoring would be conducted in accordance with 8 Star Alaska's NMFS-approved Marine Mammal Monitoring and Mitigation Plan, dated April 4, 2025, and included as Appendix A in its application

tat ( 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 during pile driving and removal would be conducted by NMFS-approved PSOs in a manner consistent with the following:

• 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 must 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. PSOs may also substitute Alaska native traditional knowledge for experience. (NMFS recognizes that PSOs with traditional knowledge may also have prior experience and be eligible to serve as the lead PSO.).

• 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 this rule

pecies and is affected by weather conditions. For anchor handling, two PSOs would be on the barge, and one PSO would always be on duty.

PSOs would not exceed 4 consecutive watch hours, would have at least a two-hour break between watches, and would not exceed a watch schedule of more than 12 hours per 24-hour period. PSOs would have no other construction-related tasks while conducting monitoring. Monitoring would be conducted from 30 minutes prior to activity (pile driving or anchor handling), throughout the time of the activity (pile driving or anchor handling), and for 30 minutes following the conclusion of the activity (pile driving or anchor handling). PSOs would monitor using the naked eye, standard (7×) binoculars, and high-magnification (25×) binoculars. Monitoring distances would be measured with range finders, and distances to animals must be based on the best estimate of the PSO, relative to known distances to objects in the vicinity of the PSO.

Acoustic Monitoring

8 Star Alaska would conduct SSV in accordance with accepted methodology as described in the Sound Source Verification Plan, which 8 Star Alaska would develop after its contractor is selected. NMFS would review and approve the plan prior to implementation. 8 Star Alaska would conduct SSV at the beginning of pile driving to characterize the sound levels associated with different pile and hammer types and assess attenuation devices, such as bubble curtains. The SSV would be conducted in accordance with the following conditions:

• 8 Star Alaska must measure a minimum of two piles of each type and size

eport would be submitted to NMFS for approval within five days after finalization of field measurements and report data. If appropriate, the results of the SSV report could be used to adjust the extent of the Level A and Level B harassment zones for in-water pile driving.

Reporting

8 Star Alaska would submit interim monthly reports for all months in which pile driving or anchor handling occurs. Monthly reports would be due 14 days after the conclusion of each calendar month, and must include a summary of marine mammal species and behavioral observations, delays, and activities completed. They would also include an assessment of the amount of work (pile driving and anchor handling) remaining to be completed, in addition to the number of CIBWs observed within estimated harassment zones to date.

8 Star Alaska would submit draft annual reports to NMFS within 90 calendar days of the completion of construction (pile driving, anchor handling) each year. Each report would include an overall description of all work completed, a narrative regarding marine mammal sightings, and associated marine mammal observation data sheets (data must be submitted

electronically in a format that can be queried such as a spreadsheet or database). Specifically, the report would include the following information:

• Date and time that monitored activity begins or ends;

• Activities occurring during each observation period, including (a) the type of activity; (b) the total duration of each type of activity; (c) when nighttime operations were required; (d) the number and type of piles that were driven and the method ( e.g., impact, vibratory), and (e) total duration of driving time for each pile (vibratory driving) and total number of strikes for each pile (impact driving)

ies occurring during each observation period, including (a) the type of activity; (b) the total duration of each type of activity; (c) when nighttime operations were required; (d) the number and type of piles that were driven and the method ( e.g., impact, vibratory), and (e) total duration of driving time for each pile (vibratory driving) and total number of strikes for each pile (impact driving).

• PSO locations during marine mammal monitoring;

• Environmental conditions during monitoring periods (at the beginning and end of the PSO shift and whenever conditions change significantly), including Beaufort sea state, tidal state, and any other relevant weather conditions, including cloud cover, fog, sun glare, overall visibility to the horizon, and estimated observable distance;

• Upon observation of a marine mammal, (a) name of PSO who sighted the animal(s) and PSO location and activity at time of sighting, (b) time of sighting, (c) identification of the animal(s) ( e.g., genus/species, lowest possible taxonomic level, or unidentified), (d) PSO confidence in identification and the composition of the group if there is a mix of species, (e) distance and location of each observed marine mammal relative to the AHTs or pile being driven for each sighting, (f) estimated number of animals (min/max/best estimate), (g) estimated number of animals by cohort (adults, juveniles, neonates, group composition, etc. ), (h) animal's closest point of approach and estimated time spent within the harassment zone, (i) 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, by species; and

• Detailed information about implementation of any mitigation ( e.g., shutdowns and delays), a description

uding 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, by species; and

• Detailed information about implementation of any mitigation ( e.g., shutdowns and delays), a description of specific actions that ensued, and resulting changes in behavior of the animal(s), if any.

If no comments are received from NMFS within 30 days of receipt of the draft report, the report would be considered final. If comments are received, 8 Star Alaska would submit a final report addressing NMFS' comments within 30 days following receipt of any NMFS comments on the draft reports.

In the event that personnel involved in 8 Star Alaska's activities discover an injured or dead marine mammal, 8 Star Alaska would report the incident to the Office of Protected Resources, NMFS, and to the Alaska Regional Stranding Coordinator as soon as feasible. If the death or injury was clearly caused by the specified activity, 8 Star Alaska would immediately cease the specified activities until NMFS is able to review the circumstances of the incident and determine what, if any, additional measures are appropriate to ensure compliance with the incidental take authorization. 8 Star Alaska would not resume their activities until notified by NMFS. The report would include the following information:

• Time, date, and location (latitude and 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

th 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 majority of our analysis applies to all species listed in table 4, except for CIBWs, given that the anticipated effects of this activity on these different marine mammal stocks are expected to be similar. For CIBWs, there are meaningful differences in anticipated responses to activities, impact of expected take on the population, or impacts on habitat; therefore, we provide a separate independent detailed analysis for CIBWs following the analysis for other species for which we propose to authorize take.

NMFS has identified several key factors to assess whether potential impacts associated with a specified activity should be considered negligible. These include (but are not limited to) the type and magnitude of taking, the amount and importance of the available habitat for the species or stock that is affected, the duration of the anticipated effect on the individuals, and the status of the species or stock. The potential effects of the specified activity on humpback whales, minke whales, gray whales, fin whales, killer whales, Dall's porpoises, harbor porpoises, Pacific white-sided dolphins, Steller sea lions, harbor seals, and California sea lions are discussed below. These factors also apply to CIBWs; however, additional analysis for CIBWs is provided in a separate sub-section below.

8 Star Alaska's specified activities have the potential to disturb or displace marine mammals, and the number of takes proposed for authorization for 8 Star Alaska's activities have been identified above in the Estimated Take of Marine Mammals section

r, the project area represents a small portion of available foraging habitat and impacts on marine mammal feeding for all species should be minimal.

We anticipate that any potential reactions and behavioral changes would subside quickly when the exposures cease, and, therefore, we do not expect long-term adverse consequences from 8 Star Alaska's proposed activities for individuals of any species. The intensity of harassment events would be minimized through use of mitigation measures described herein, which were not quantitatively factored into the take estimates. 8 Star Alaska would use PSOs to monitor for marine mammals before commencing any of the specified activities, which would minimize the potential for marine mammals to be present within the estimated Level A and Level B harassment areas, further reducing the likely amount of any potential Level A or Level B harassment. Further, given the absence of any major rookeries or areas of known biological significance for marine mammals ( e.g., foraging hot spots) within the estimated harassment zones (other than critical habitat and a BIA for CIBWs as described below), we predict that potential takes by Level B harassment would have an inconsequential short-term effect on individuals and would not result in population-level impacts.

Theoretically, repeated, sequential exposure to elevated noise from vibratory and impact pile driving and noise from AHTs over a long duration could result in more severe impacts to individuals that could affect individual fitness or reproductive success (via sustained or repeated disruption of important behaviors such as feeding, resting, traveling, and socializing; Southall et al., 2007). Alternatively, marine mammals exposed to repetitious sounds may become habituated, desensitized, or tolerant after initial exposure to these sounds (reviewed by Richardson et al., 1995; Southall et al., 2007)

ld affect individual fitness or reproductive success (via sustained or repeated disruption of important behaviors such as feeding, resting, traveling, and socializing; Southall et al., 2007). Alternatively, marine mammals exposed to repetitious sounds may become habituated, desensitized, or tolerant after initial exposure to these sounds (reviewed by Richardson et al., 1995; Southall et al., 2007). Cook Inlet is a regional hub of marine transportation and is used by various classes of vessels, including container ships, bulk cargo freighters, tankers, commercial and sport-fishing vessels, and recreational vessels. Off-shore vessels, tug vessels, and tour boats represent 86 percent of the total

operating days for vessels in Cook Inlet (Bureau of Ocean Energy Management (BOEM), 2016). Given that marine mammals still frequent and use Cook Inlet despite being exposed to anthropogenic sounds such as those produced by pile driving, tug boats and other vessels across many years, and that it is unlikely that any individual would be exposed to repeated, sequential exposures or repetitious sounds from 8 Star Alaska's activities, no impacts to the reproduction or survival of any marine mammal individuals from the additional noise produced by the specified activities are anticipated.

NMFS anticipates take by Level A harassment of three species due to the potential that an animal could enter and remain within the area between a Level A harassment zone and shutdown zone during impact pile driving for a duration long enough to be taken by Level A harassment. Any take by Level A harassment is expected to arise from, at most, a small degree of AUD INJ, because 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 AUD INJ. 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

ent is expected to arise from, at most, a small degree of AUD INJ, because 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 AUD INJ. 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. Because of the small degree anticipated, though, any PTS or TTS potentially incurred here is not expected to adversely impact individual fitness, let alone annual rates of recruitment or survival.

Impacts to marine mammal prey species are also expected to be minor and temporary and to 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. Overall, as described above, the area anticipated to be impacted by 8 Star Alaska's planned activities is very small compared to the available surrounding habitat and does not include habitat of particular importance to marine mammals. The most likely impact to prey would be temporary behavioral avoidance of the immediate area. While AHTs are engaged in anchor handling and pile driving activities, it is expected that some fish would temporarily leave the area of disturbance ( e.g., Nakken, 1992; Olsen, 1979; Ona and Godo, 1990; Ona and Toresen, 1988), thus impacting marine mammals' foraging opportunities in a limited portion of their foraging range. But, because of the relatively small area of the habitat that may be affected and lack of any foraging habitat of particular importance, the impacts to marine mammal habitat are not expected to cause significant or long-term negative consequences. Additionally, the habitat within the estimated acoustic footprint is not known to be heavily used by marine mammals

of the specified activity by minimizing the numbers of marine mammals exposed to sound and the intensity of the exposures.

Cook Inlet Beluga Whales

For CIBWs, we further discuss our preliminary negligible impact findings in addition to the findings discussed above for all species in the context of potential impacts to the endangered stock based on our evaluation of the take proposed (table 17).

All of 8 Star Alaska's activities would be conducted in a manner implementing best management practices to preserve water quality, and no work would occur around creek mouths or river systems leading to prey abundance reductions. In addition, no physical structures would restrict passage, though impacts to the acoustic habitat are relevant and discussed here. While the specified activities would occur within CIBW Critical Habitat Area 2, and the CIBW small and resident BIA (see the Description of Marine Mammals in the Area of Specified Activities section), monitoring data from similar regional activities suggest that the presence of tugs under load do not discourage CIBWs from transiting throughout Cook Inlet and between critical habitat areas and that the whales do not abandon critical habitat areas ( e.g., Horsley and Larson, 2023, 2024). In addition, large numbers of CIBWs have continued to use Cook Inlet and pass through the area, likely traveling to critical foraging grounds in upper Cook Inlet, while noise-producing anthropogenic activities, including vessel use, have taken place during the past 2 decades ( e.g., Shelden et al., 2013, 2015b, 2017, 2022; Shelden and Wade, 2019; Goetz et al., 2023). These findings are not surprising as food is a strong motivation for marine mammals. As described in Forney et al. (2017), animals typically favor particular areas because of their importance for survival ( e.g., feeding or breeding), and leaving may have significant costs to fitness (reduced foraging success, increased predation risk, increased exposure to other anthropogenic threats)

als' fitness for reproduction or survival.

Although data demonstrate that CIBWs are not abandoning the planned project area during anthropogenic activities, results of an expert elicitation (EE) at a 2016 workshop, which predicted the impacts of noise on CIBW survival and reproduction given a specific amount of lost foraging opportunities, helped to inform our assessment of impacts on this stock. The 2016 EE workshop used conceptual models of an interim population consequences of disturbance (PCoD) for marine mammals (National Research Council (NRC), 2005, New et al., 2014, Tollit et al., 2016) to help in understanding how noise-related stressors might affect vital rates (survival, birth rate and growth) for CIBW (King et al., 2015). NMFS (2016) suggests that the main direct effects of noise on CIBWs are likely to be through masking of vocalizations used for communication and prey location and habitat degradation. The 2016 workshop on CIBWs was specifically designed to provide regulators with a tool to help understand whether chronic and acute anthropogenic noise from various sources and projects are likely to be limiting recovery of the CIBW population. The full report can be found at https://www.smruconsulting.com/publications/ with a summary of the expert elicitation portion of the workshop below.

For each of the noise effect mechanisms chosen for the EE, the experts provided a set of parameters and values that determined the forms of a relationship between the number of days of disturbance a female CIBW experiences in a particular period and the effect of that disturbance on her energy reserves

take on that day). The day of disturbance considered in the context of the report is notably more severe than any Level B harassment expected to result from these activities, which as described is expected to be comprised predominantly of temporary modifications in the behavior of individual CIBWs ( e.g., faster swim speeds, longer dives, decreased sighting durations, alterations in communication). Also, NMFS is proposing to authorize a maximum of 30 instances of take in one year (with 11 instances of take proposed for each of the other four years of the rule), with the instances representing disturbance events within a day—this means that either 30 different individual CIBWs are disturbed on no more than 1 day each, or some lesser number of individuals may be disturbed on more than 1 day, but with the product of individuals and days not exceeding 30. Given the overall take proposed for authorization, it is unlikely that any one CIBW would be disturbed on more than a couple of days.

Further, 8 Star Alaska would implement mitigation measures specific to CIBWs. 8 Star Alaska would not begin anchor handling activities should a CIBW be observed within the Level B harassment zone. In addition, 8 Star Alaska would implement shutdown zones for pile driving for beluga whales that extend to the Level B harassment isopleth, or in cases where the Level B harassment zones are too large to fully observe, to the extent that PSOs can observe, minimizing Level B harassment of beluga whales. While Level B harassment is proposed for authorization, these measures, along with other mitigation measures described herein, would limit the severity of the effects of that Level B harassment to behavioral changes such as increased swim speeds, changes in diving and surfacing behaviors, and alterations to communication signals, not the loss of foraging capabilities. NMFS is also proposing time/area restrictions, such that noise would be restricted in the Susitna delta during critical foraging times and high CIBW density

d stock abundance value for the Alaska stock of minke whale did not allow for the calculation of an expected percentage of the population that may be affected. The most relevant estimate of partial stock abundance is 1,233 minke whales in coastal waters of the Alaska Peninsula and Aleutian Islands (Zerbini et al., 2006). NMFS is proposing to authorize an annual maximum of three takes of this stock. Comparison to the best estimate of stock abundance shows that, at most, less than one percent of the stock would expected to be impacted.

The Alaska stock of Dall's porpoise has no official NMFS abundance estimate for this area, as the most recent estimate is greater than 8 years old. As described in the 2021 Alaska SAR (Muto et al., 2022) the minimum population estimate is assumed to correspond to the point estimate of the 2015 vessel-based abundance computed by Rone et al. (2017) in the Gulf of Alaska (N = 13,110; CV = 0.22). NMFS is proposing to authorize an annual maximum of 6 takes of the stock. Comparison to the minimum population estimate shows that, at most, 0.05 percent of the stock would be expected to be impacted.

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 promulgate regulations, 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

a's proposed activities.

Adaptive Management

These proposed regulations contain an adaptive management component. Our understanding of the effects of pile driving and AHTs engaged in anchor handling ( e.g., acoustic stressors) on marine mammals continues to evolve, which makes the inclusion of an adaptive management component both valuable and necessary within the context of 5-year regulations.

The monitoring and reporting requirements in this proposed rule would provide NMFS with information that helps us to better understand the impacts of the project's activities on marine mammals and informs our consideration of whether any changes to mitigation and monitoring are appropriate. The use of adaptive management would allow NMFS to consider new information and modify mitigation, monitoring, or reporting requirements, as appropriate, with input from 8 Star Alaska regarding practicability, if such modifications will have a reasonable likelihood of more effectively accomplishing the goals of the measures.

The following are some of the possible sources of applicable data that would be considered through the adaptive management process: (1) results from monitoring reports, including the monthly and annual reports required; (2) results from research on marine mammals, noise impacts, or other related topics; and (3) any information which reveals that marine mammals may have been taken in a manner, extent, or number not authorized by these regulations or LOAs issued pursuant to these regulations. Adaptive management decisions could be made at any time as new information warrants. NMFS could consult with 8 Star Alaska regarding the practicability of the modifications.

Endangered Species Act

Section 7(a)(2) of the ESA of 1973 (16 U.S.C. 1531 et seq

zation. This proposed rule and referenced documents provide all environmental information relating to our proposed action for public review.

List of Subjects in 50 CFR Part 217

Administrative practice and procedure, Acoustics, Endangered and threatened species, Fish, Fisheries, Marine mammals, Penalties, Reporting

and recordkeeping requirements, Wildlife.

Dated: July 22, 2025. Samuel D. Rauch III, Deputy Assistant Administrator for Regulatory Programs, National Marine Fisheries Service.

For reasons set forth in the preamble, NMFS proposes to revise 50 CFR part 217 as follows:

PART 217—REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS

1. The authority citation for part 217 continues to read as follows:

Authority:

16 U.S.C 1361 et seq.

2. Revise subpart E, consisting of §§ 217.40 through 217.49, to read as follows

Subpart E—Taking Marine Mammals Incidental to 8 Star Alaska LNG Facilities Construction in Cook Inlet, Alaska

Sec. 217.40 Specified activity and specified geographical region. 217.41 Effective dates. 217.42 Permissible methods of taking. 217.43 Prohibitions. 217.44 Mitigation requirements. 217.45 Requirements for monitoring and reporting. 217.46 Letters of Authorization. 217.47 Modifications of Letters of Authorization. 217.48-217.49 [Reserved] Subpart E—Taking Marine Mammals Incidental to 8 Star Alaska Liquefied Natural Gas Facilities Construction in Cook Inlet, Alaska

§ 217.40 Specified activity and specified geographical region. (a) Regulations in this subpart apply only to 8 Star Alaska or successor entities and those persons it authorizes or funds to conduct activities on its behalf for the taking of marine mammals that occurs in the area outlined in paragraph (b) of this section and that occurs incidental to the activities described in paragraph (c) of this section. Requirements imposed on 8 Star Alaska must be implemented by those persons it authorizes or funds to conduct activities on its behalf.

opriate LOA.

§ 217.43 Prohibitions. Except for the taking permitted in § 217.42 and authorized by the LOA issued under § 216.106 of this chapter and this subpart, it is unlawful for any person to do any of the following in connection with the specified activities:

(a) Violate or fail to comply with the terms, conditions, and requirements of this subpart or the LOA issued under this subpart;

(b) Take any marine mammal not specified in § 217.42;

(d) Take any marine mammal specified in § 217.42 after NMFS determines such taking results in more than a negligible impact on the species or stock of such marine mammal; or

(e) Take any marine mammal specified in § 217.42 after NMFS determines such taking results in an unmitigable adverse impact on the species or stock of such marine mammal for taking for subsistence uses.

§ 217.44 Mitigation requirements. When conducting the activities identified in § 217.40(c), the mitigation measures contained in this section and any LOAs issued under § 216.106 of this chapter and this subpart must be implemented. These mitigation measures include:

(a) A copy of any issued LOA must be in the possession of 8 Star Alaska, its designees, and work crew personnel operating under the authority of the issued LOA.

(b) 8 Star Alaska must employ protected species observers (PSOs) and establish monitoring locations pursuant to § 217.45.

(c) 8 Star Alaska must implement shutdown zones for pile driving and clearance zones for anchor handling with radial distances as identified in any LOA issued under §§ 216.106 of this chapter and 217.46.

(1) Monitoring of shutdown or clearance zones must take place from 30 minutes prior to commencing impact and vibratory pile driving or use of tugs for anchor-handling (AHTs), or if there is a 30-minute lapse in such activities, and must continue for 30 minutes following conclusion of the activity.

halted upon observation of a marine mammal entering or within the shutdown zone. If pile driving is halted or delayed due to the presence of a marine mammal, the activity may not commence or resume until either the animal has voluntarily left and has been visually confirmed beyond the shutdown zone or 15 minutes (pinnipeds) or 30 minutes (cetaceans) have passed without re-detection of the animal.

(i) If work ceases for more than 30 minutes, the shutdown zones must be cleared again for 30 minutes prior to reinitiating pile driving. A determination that the pile driving shutdown zone is clear must be made during a period of good visibility.

(ii) If a shutdown procedure should be initiated but human safety is at risk as determined by the best professional judgment of the vessel operator or project engineer, the in-water activity, including pile driving, is allowed to

continue until the risk to human safety has dissipated. In this scenario, pile driving may continue only until the current segment of the pile is driven; no additional sections of pile or additional piles may be driven until the Lead PSO has determined that the shutdown zones are clear of marine mammals and for Cook Inlet beluga whales (CIBW), any observed whale(s) is at least 100 meters (m) past the shutdown zone and on a path away from the zone.

(3) If a PSO(s) can no longer effectively monitor the entirety of the corresponding shutdown zone during impact pile driving, or at least 2 km during vibratory pile driving, due to environmental conditions ( e.g., fog, rain, wind), pile driving may continue only until the current segment of the pile is driven; no additional sections of pile or additional piles may be driven until conditions improve such that the zone can be effectively monitored. If the shutdown zone cannot be monitored for more than 15 minutes, the entire zone must be cleared again for 30 minutes prior to reinitiating pile driving.

ollowing cessation of impact pile driving for a period of 30 minutes or longer.

(e) 8 Star Alaska must coordinate with local subsistence communities as described in their Stakeholder Engagement Plan, notify the communities of any changes in operation, and work with communities to avoid or mitigate impacts to subsistence harvest through pre-construction planning, communication, or other actions.

(f) Between April 15 and October 15, 8 Star Alaska must not conduct pile driving or AHT activities with Level B harassment isopleths that would extend shoreward of the MLLW line in the Susitna Delta (Beluga River to the Little Susitna River) and project vessel(s) operating in or transiting through Cook Inlet must maintain a distance of at least 1.5 miles nautical miles seaward of the MLLW line in the Susitna Delta (Beluga River to the Little Susitna River).

(g) Operators of vessels must avoid approaching within 100 yards (92 m) of marine mammals.

(h) If a whale's course and speed are such that it would likely cross in front of a vessel that is underway or approach within 100 yards (92 m) of the vessel, if maritime conditions safely allow, and if practicable, the engine must be put in neutral and the whale must be allowed to pass beyond the vessel.

(i) Vessel operators must avoid placing the vessel in the path of a whale and must not cut in front of the whale in a way or at a distance the causes the whale to change direction of travel or behavior (including breathing/surface pattern).

(j) When within 300 yards (274 m) of a whale, vessels must travel at less than 5 knots (9 km/hour), and vessel operators must avoid changes in direction and speed unless doing so is necessary for maritime safety.

(k) Vessel operators must reduce speed to 10 knots (18.5 km/hour) or less when weather conditions reduce visibility to 1.6 km (1 mile) or less.

(including breathing/surface pattern).

(k) Vessel operators must reduce speed to 10 knots (18.5 km/hour) or less when weather conditions reduce visibility to 1.6 km (1 mile) or less.

(l) For vessels operating in the Susitna Delta Exclusion Zone, the following must be implemented:

(1) All project vessels operating within the designated Susitna Delta Exclusion Area must maintain a speed over ground below 4 knots (7.4 km/hour). PSOs must note the numbers, date, time, coordinates, and proximity to vessels of all belugas observed during operations and report these observations to NMFS in monthly PSO reports.

(2) Vessel crew must be trained to monitor for Endangered Species Act (ESA)-listed species prior to and during all vessel movements within the Susitna Delta Exclusion Zone. The vessel crew must report sightings to the PSO team for inclusion in the overall sighting database and reports.

(3) Vessel operators must not move their vessels when they are unable to adequately observe the 100-m zone around vessels under power (in gear) due to darkness, fog, or other conditions, unless nec

This text is long and has been trimmed here. Open the source document for the complete record.

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.