Acoustic Monitoring and Prey Association for Beluga Whale, Delphinapterus leucas, and Harbor Porpoise, Phocoena phocoena, off Two River Mouths in Yakutat Bay, Alaska

September 06, 2018

Yakutat Bay on the eastern Gulf of Alaska is a glacial fjord influenced by the activity of major tidewater glaciers at its head and is a region of high marine biodiversity. Two marine mammal species that live there year-round are the beluga whale, Delphinapterus leucas, and the harbor porpoise, Phocoena phocoena.

The exact number of belugas in Yakutat Bay is unknown, but the best present estimate is 10–12 whales (O’Corry-Crowe et al., 2015; O’CorryCrowe1). Genetic studies indicate that this small group of belugas is isolated from the nearest population, in Cook Inlet; thus they may be resident in the Yakutat Bay region year-round (O’Corry-Crowe et al., 2015). Because these whales have such a restricted home range and small population size but are reproductive, they have a unique ecology (O’Corry-Crowe et al.1, 2). The core area for these animals appears to be Disenchantment Bay, at the far northeast end of Yakutat Bay, located between four actively calving tidewater glaciers (Fig. 1). Both opportunistic historical sightings (Laidre et al., 2000) and traditional ecological knowledge from the Tlingit Tribe (Lucey et al., 2015) suggest that belugas have inhabited Yakutat Bay since at least the 1930’s, but they likely originated from Cook Inlet (O’Corry-Crowe et al., 2015).

Little is also known about the numbers and distribution of harbor porpoise in the bay, although they are seen more frequently than are beluga by the residents of Yakutat. Yakutat Bay is one of the regions in southeastern Alaska that has relatively high densities of harbor porpoises (Hobbs and Waite, 2010). Harbor porpoises are sighted both within and outside the bay in nearshore waters (Dahlheim et al., 2000; Hobbs and Waite, 2010). While there is little knowledge on historical beluga presence in Yakutat Bay, harbor porpoises have occupied the area since before human settlement and at one time were hunted for food by Yakutat Tlingit (De Laguna, 1972).

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Last updated by Alaska Fisheries Science Center on 04/24/2019

Beluga Whale Cook Inlet Beluga Whale Harbor porpoise