Distribution, Abundance, Harvest, and Status of Western Alaska Beluga Whale, Delphinapterus leucas, Stocks

The Alaska Beluga Whale Committee co-manages three western Alaska beluga whale Delphinapterus leucas, stocks with the National Marine Fisheries Service, NOAA, and has conducted studies on stock identity, distribution, abundance, and subsistence harvests. Studies of mitochondrial DNA revealed substantial differentiation among belugas that use summering areas in Bristol Bay, the eastern Bering Sea, and the eastern Chukchi Sea, and there is little overlap in their seasonal distributions. The Bristol Bay stock summers in bays in inner Bristol Bay and winters in outer Bristol Bay. Abundance estimates from aerial surveys increased by more than 4% per year during 1994–2005. Survey counts in 2016 were similar to 2004– 2005 indicating that the population may now be stable. Survey results and a genetics mark-recapture study indicate a population of approximately 2,000 whales. The average annual Alaska Native subsistence harvest over the past decade (23) is below the calculated potential biological removal (PBR; 39-43). The eastern Bering Sea beluga stock concentrates in summer off the Yukon River Delta and in Norton Sound and in winter moves offshore in the eastern Bering Sea. Abundance has been estimated at approximately 9,242 based on aerial survey data collected in 2017. The average annual subsistence harvest, plus the estimated number of struck and lost belugas, is 215 and exceeds the PBR calculated from this abundance estimate (201), but the abundance estimate is thought to be biased low and local and traditional knowledge does not indicate any decrease in abundance or availability. The eastern Chukchi Sea stock is migratory, wintering in the northern Bering Sea, moving north through the eastern Chukchi Sea in spring, and summering in the Beaufort Sea and Arctic Ocean. It is large, estimated at approximately 20,000 animals based on 2012 aerial surveys. The average annual subsistence harvest (57) is well below PBR (293). Few significant threats to persistence of western Alaska beluga stocks have been identified, although climate warming and declines in sea ice and industrial activities related to resource development and increases in commercial shipping are of concern and could pose challenges in the future. Continued monitoring of population size and trend, subsistence harvest, and health of western Alaska belugas is warranted. Introduction Beluga whales, Delphinapterus leucas (also called white whales), are a conspicuous and important component of the marine mammal fauna of western Alaska. Early reports indicated regular spring, summer, and fall occurrences of belugas in the Bering Sea in Bristol Bay (Brooks et al.1; Len1Brooks, J. W., A. S. Mossman, and H. Z. Hansen. 1955. Predator control and investigation: beluga investigation. In 1955 annual report, p. 98–106. Alaska Fish. Board, Alaska Dep. Fish., Rep. 7, Juneau (avail. at http://www.arlis.org/ docs/vol1/A/31110164etc/31110164etc-1955. pdf#page=97). sink2), Norton Sound and the Yukon Delta (Nelson, 1887; Zagoskin, 1967), and in the Chukchi Sea in Kotzebue Sound and along lagoons near Point Lay (Nelson, 1887; Foote and Williamson, 1966; Childs3). Traditional knowledge of Alaska Natives indicat2Lensink, C. J. 1961. Status report: beluga studies. Alaska Dep. Fish Game, Div. Biol. Res., Unpubl. Rep., Juneau (avail. at http://www.adfg. alaska.gov/static/home/library/pdfs/wildlife/research_pdfs/status_report_beluga_studies_1961. pdf). 3Childs, H. E., Jr. 1969. Birds and mammals of the Pitmegea River Region, Cape Sabine, northwestern Alaska. Biol. Pap. No. 10, Univ. Alaska, Fairbanks, 76 p. (avail. at https://scholarworks. alaska.edu/handle/11122/1432). ed that these occurrences represented long established migration routes and summer concentration areas, and that belugas were an important subsistence resource harvested at many coastal villages (Huntington et al., 1999; Neakok et al.4; Chythlook and Coiley5). Research on belugas in Alaska initially focused on competition with commercial fisheries but later included potential impacts of proposed oil and gas leasing. Belugas in Bristol Bay were the subject of early scientific attention mostly because the largest commercial sockeye salmon, Oncorhynchus nerka, fishery in the world occurs there (Jones et al.6) and 4Neakok, W., D. Neakok, W. Bodfish, D. Libbey, E. S. Hall, Jr., and the Point Lay elders. 1985. To keep the past alive: the Point Lay cultural resource site survey. North Slope Borough, Barrow, AK, 111 p. 5Chythlook, M., and P. Coiley 1994. The subsistence use of beluga whale in Bristol Bay by Alaska Natives, 1993. Tech. Paper No. 231. Alaska Dep. Fish Game, Div. Subsistence, Juneau, AK, 29 p. 6Jones, M., T. Sands, S. Morstad, P. Salomone, G. Buck, F. West, C. Brazil, and T. Krieg. 2013. 2012 Bristol Bay area annual management report. Alaska Dep. Fish Game, Fish. Manage.