2024-23681. Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Sand Island Pile Dikes Repairs on the Columbia River

Table 1—Species Likely Impacted by the Specified Activities

Common name	Scientific name	Stock	ESA/MMPA status; strategic (Y/N) 1	Stock abundance (CV, N min , most recent abundance survey) 2	PBR	Annual M/SI 3
Order Cetartiodactyla—Cetacea—Superfamily Mysticeti (baleen whales)
Family Balaenopteridae (rorquals):
Humpback whale	Megaptera novaeangliae	Central America/Southern Mexico—California/Oregon/Washington	E, D, Y	1,494 (0.171, 1,284, 2021)	3.5	14.9
		Mainland Mexico—CA/OR/WA	T, D, Y	3,477 (0.101, 3,185, 2018)	43	22
Superfamily Odontoceti (toothed whales, dolphins, and porpoises)
Family Delphinidae:
Killer Whale	Orcinus orca	West Coast Transient	-, -, N	349 4 (N/A, 349, 2018)	3.5	0.4
Family Phocoenidae (porpoises):
Harbor Porpoise	Phocoena phocoena	Northern Oregon/Washington Coast	-, -, N	22,074 (0.391, 16,068, 2024)	161	3.2
Order Carnivora—Superfamily Pinnipedia
Family Otariidae (eared seals and sea lions):
California Sea Lion	Zalophus californianus	U.S.	-, -, N	257,606 (N/A, 233,515, 2014)	14,011	>321
Steller Sea Lion	Eumetopias jubatus	Eastern	-, -, N	36,308 (N/A, 36,308, 2022) 5	2,592	112
Family Phocidae (earless seals):
Harbor Seal	Phoca vitulina	Oregon/Washington Coast	-, -, N	24,732 6 (UNK, UNK, 1999)	UND	10.6
Northern Elephant Seal	Mirounga angustirostris	California Breeding	-, -, N	187,386 (N/A, 85,369, 2013)	5,122	13.7
1 ESA status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). A dash (-) indicates that the species is not listed under the ESA or designated as depleted under the MMPA. Under the MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
2 NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/​national/​marine-mammal-protection/​marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; N min is the minimum estimate of stock abundance.
3 These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury from all sources combined ( e.g., commercial fisheries, ship strike). Annual mortality/serious injury (M/SI) often cannot be determined precisely and is in some cases presented as a minimum value or range.
4 Based on counts of individual animals identified from photo-identification catalogues. Surveys for abundance estimates of these stocks are conducted infrequently.
5 Nest is best estimate of counts, which have not been corrected for animals at sea during abundance surveys. Estimates provided are for the U.S. only.
6 The abundance estimate for this stock is greater than 8 years old and is therefore not considered current. PBR is considered undetermined for this stock, as there is no current minimum abundance estimate for use in calculation. We nevertheless present the most recent abundance estimates, as these represent the best available information for use in this document.

Humpback Whales

On September 8, 2016, NMFS divided the once single species into 14 distinct population segments (DPS) under the ESA, removed the species-level listing as endangered, and, in its place, listed four DPSs as endangered and one DPS as threatened (81 FR 62259, September 8, 2016). The remaining nine DPSs were not listed. There are four DPSs in the North Pacific, including Western North Pacific and Central America, which are listed as endangered, Mexico, which is listed as threatened, and Hawaii, which is not listed.

The 2022 Pacific SARs described a revised stock structure for humpback whales which modifies the previous stocks designated under the MMPA to align more closely with the ESA-designated DPSs (Caretta et al., 2023; Young et al., 2023). Specifically, the three previous North Pacific humpback whale stocks (Central and Western North Pacific stocks and a CA/OR/WA stock; take of humpback whales authorized through the original Year 2 IHA was from the latter stock) were replaced by five stocks, largely corresponding with the ESA-designated DPSs. These include Western North Pacific and Hawaii stocks and a Central America/Southern Mexico-CA/OR/WA stock (which corresponds with the Central America DPS). The remaining two stocks, corresponding with the Mexico DPS, are the Mainland Mexico-CA/OR/WA and Mexico-North Pacific stocks (Caretta et al., 2023; Young et al., 2023). The former stock is expected to occur along the west coast from California to southern British Columbia, while the latter stock may occur across the Pacific, from northern British Columbia through the Gulf of Alaska and Aleutian Islands/Bering Sea region to Russia. Only the Mainland Mexico-CA/OR/WA and Mexico-North Pacific stocks are expected to be affected by the specified activity, and take previously authorized for the CA/OR/WA stock is here reallocated to these two newly designated stocks, as discussed below.

We have determined that no new information affects our original analysis of potential impacts under the initial Year 2 IHA.

Potential Effects on Marine Mammals and Their Habitat

A description of the potential effects of the specified activities on marine mammals and their habitat may be found in the documents supporting the issuance of the original year 2 IHA, which remains applicable to the modification of the IHA. NMFS is not ( print page 82989) aware of new information regarding potential effects.

Estimated Take

A detailed description of the methods and inputs used to estimate authorized take for the specified activities are found in the Federal Register notice of proposed IHAs (87 FR 3948, July 1, 2022). The types and sizes of piles, ensonified areas and source levels, and methods of pile driving remain unchanged from the IHA.

The modification addresses USACE's concerns that the ongoing construction activities could result in exceeding levels of authorized take of humpback whale and killer whale. Sightings of humpback whales have increased in the project area from previous years. Humpback whale feeding groups have begun utilizing the mouth of the Columbia River as foraging ground, arriving in the lower Columbia estuary as early as mid-June, and have been observed as late as mid-November with whale peak abundance coinciding with the peak abundance of forage fish in mid-summer. Humpback whales were observed in the immediate vicinity of West and East Sand Islands in late summer and fall of 2015 and 2016. They were also observed in the area in 2017 and 2019, but their presence was not documented in 2018. Under the 2023 year 1 IHA, no humpback whales were detected in 34 days of pile driving.

According to Wade et al. (2021), the probabilities that humpback whales encountered in Oregon and California ( i.e., south of the Columbia River) belong to various DPSs are as follows: Mexico DPS, 58 percent; and Central America DPS, 42 percent. The probabilities that humpback whales found in Washington and Southern British Columbia waters ( i.e., north of the Columbia River) belong to various DPSs are as follows: Hawai'i DPS, 69 percent; Mexico DPS, 25 percent; and Central America DPS, 6 percent (Wade et al., 2021). In this area, these DPSs correspond with the newly designated Mainland Mexico-CA/OR/WA, Central America/Southern Mexico-CA/OR/WA, and Hawaii stocks, respectively. Since the Columbia River is considered the dividing line between these two areas, the correct proportion of humpback whales likely to be encountered is unclear, i.e., whether the probabilities are closer to those assumed for the regions north or south of the Columbia River. NMFS conservatively assumes here that take of humpback whale would be the same as at a location south of the Columbia River, with 58 percent likely from the Mexico stock and 42 percent from the Central America stock.

The USACE has recorded four takes of humpback whale by Level B harassment as of September 11, 2024 after 24 days of in-water pile driving work which equates to a daily take rate of 0.17 animals/day. NMFS had originally authorized six takes by Level B harassment. With 80 days in-water work remaining, the projected take at the rate described above would result in 14 takes in addition to the 4 takes already recorded. NMFS is further authorizing an additional 10 takes by Level B harassment to ensure adequate consideration of likely take in light of the present increased occurrence of humpback whales. Therefore, NMFS has authorized a total of 28 humpback whale takes by Level B harassment.

The USACE also requested an increase in authorized take by Level B harassment of killer whales. NMFS had authorized two takes by Level B harassment under the original year 2 IHA. Under the 2023 year 1 IHA, no killer whales were detected in 34 days of pile driving according to the monitoring report submitted by the USACE. Based on recent anecdotal sightings, the USACE was concerned about potentially exceeding authorized take. The USACE felt that killer whales are more likely to enter into the project than previously considered. NMFS agreed with this assessment and modified the original IHA accordingly. The modal group sizes for transient killer whales ranges from three to four (Shields et al. 2018). NMFS assumed take of 2 groups of 4 in addition to the 2 already authorized in the year 2 IHA for a total of 10 takes by Level B harassment.

Table 2 shows the authorized take of all marine mammals by Level A and Level B harassment including revisions to authorized take of humpback whale and killer whale.

Table 2—Authorized Take of Marine Mammals by Level A and Level B Harassment by Year, by Species and Stock and Percent of Take by Stock

Species	Authorized take by Level A harassment	Authorized take by Level B harassment	Total proposed take	Stock	Stock abundance	Percent of stock
Year 2:
Humpback whale 1	0	12	12	Central America/Southern Mexico—California/Oregon/Washington	1,494	<0.01
	0	16	16	Mainland Mexico—CA/OR/WA	3,477	0.46
Killer whale	0	10	10	West Coast Transient	349	0.28
Harbor porpoise	27	163	190	Northern Oregon/Washington Coast	22,074	0.86
California sea lion	0	23,421	23,421	U.S	257,606	9.09
Steller sea lion	0	29,502	29,502	Eastern	36,308	81.25
Harbor seal	54	5,361	5,415	Oregon/Washington Coast	24,732	21.89
Northern elephant seal	0	6	6	California Breeding	187,363	<0.01
1 Humpback whales from the Central America/Southern Mexico-CA/OR/WA stock and the Mainland Mexico-CA/OR/WA stock are likely to occur in the project area in the respective percentages of 42 and 58 percent (Wade et al. 2021).