2017 Copper River Delta Carcass Surveys: Annual Report

NMFS Protected Resources Division biologists conducted six survey flights of the shifting sand shoals of the Copper River Delta (Delta) from May 17 to August 17, 2017. The purpose of the flights was to search for marine mammal carcasses in an area with a history of incidental and intentional killings of marine mammals by humans, and to conduct necropsies of any observed carcasses in order to establish cause of death and collect biological samples. Carcasses were observed on all six flights, but some of the carcasses were located outside of the Copper River Delta (either in Prince William Sound or east of the Delta). At least four Steller sea lion (Eumetopias jubatus), one humpback whale (Megaptera novaeangliae), one gray whale (Eschrichtius robustus), and seven harbor seal (Phoca vitulina) carcasses were observed on the survey flights on the Delta. Four of the 11 pinniped carcasses showed evidence that they may have been intentionally killed by humans. Biologists were unable to collect samples from five pinniped carcasses, and at least one pinniped carcass was too decomposed to determine cause of death. The gray whale was too decomposed to determine cause of death. A team was able to necropsy the fresh dead humpback whale. Although cause of death was not conclusive, bruising and other tissue damage tentatively suggested vessel strike. We opportunistically examined and sampled one Steller sea lion carcass east of the survey area, and two humpback whales and an additional Steller sea lion west of the 2018 NMFS (National Marine Fisheries Service) Submitted Public Domain 1861