Acoustic Monitoring and Prey Association for Beluga Whale and Harbor Porpoise off Two River Mouths in Yakutat Bay, Alaska
Research on the ecology of beluga whales (Delphinapterus leucas) and harbor porpoises (Phocoena phocoena) in Yakutat Bay, Alaska.
Little is known about the ecology of beluga whales (Delphinapterus leucas) and harbor porpoises (Phocoena phocoena) inhabiting Yakutat Bay, Alaska. Using passive acoustic monitoring techniques, their year-round presence was monitored during June 2012 to March 2013 off the mouths of two glacial rivers: Esker Creek and Grand Wash. Fishery trawl transects were run in both areas during March to August 2013 to assess fish and invertebrate diversity and to identify potential beluga and harbor porpoise prey. Results supported year-round presence for both species, with restricted home range for beluga and a wider distribution for porpoise.
Opposite diel patterns in beluga and harbor porpoise presence suggest potential competitive overlap in prey between species. Based on trawl abundance and ubiquity, several fish and crustacean species were identified as potential prey for beluga and harbor porpoise. Results support the belief that shrimp, crab, and mysids may be an important part of beluga and porpoise diet in Yakutat. Both river mouth areas are used by harbor porpoises, but their seasonality might not be driven solely by prey diversity or abundance. Beluga detection results during a coho salmon, (Oncorhynchus kisutch), run were indicative of predation by belugas on this species during their spawning migration. This pilot study demonstrates the utility of remote, passive acoustic monitoring technology to better understand the seasonal distribution patterns and prey association of beluga and harbor porpoise in Yakutat Bay.
Manuel Castellote, Kathleen M. Stafford, A. Darcie Neff, and William Lucey. Published in Marine Fisheries Review. Doi: dx.doi.org/10.7755/MFR.77.1.1