Statewide | Mammals
2022 update of the ongoing gray whale unusual mortality event in Alaska Presenter: Caroline Cummings , caroline.cummings@noaa.gov, NOAA Fisheries, Protected Resources Division, Alaska Region Kathy Burek Huntington , avps.kbh@gmail.com, Alaska Veterinary Pathology Services Natalie Rouse , avps.natalierouse@gmail.com, Alaska Veterinary Pathology Services Sadie Wright , sadie.wright@noaa.gov, NOAA Fisheries, Protected Resources Division, Alaska Region Gay Sheffield , ggsheffield@alaska.edu, University of Alaska Fairbanks Raphaela Stimmelmayr , raphaela.stimmelmayr@north-slope.org, North Slope Borough, Department of Wildlife Management Bonnie Easley-Appleyard , bonnie.easley-appleyard@noaa.gov, NOAA Fisheries Barbara Mahoney , barbara.mahoney@noaa.gov, NOAA Fisheries, Protected Resources Division, Alaska Region Matt Van Daele , matt@sunaq.org, Sun’aq Tribe of Kodiak Natural Resources Department Since January of 2019, a significant increase in gray whale ( Eschrichtius robustus ) mortality has been observed along the west coast of North America from Mexico through Alaska. In May of 2019, the National Oceanic and Atmospheric Administration (NOAA) declared these elevated strandings an Unusual Mortality Event (UME), defined under the Marine Mammal Protection Act as “a stranding that is unexpected; involves a significant die-off of any marine mammal population; and demands immediate response.” In late winter and spring, gray whales from the eastern distinct population segment typically migrate northward along the West Coast, from mating and calving grounds in Mexico to feeding grounds in northern Alaska. In 2019, gray whale stranding events began in Mexico and followed the migration route up the coast. In Alaska, the first documented gray whale stranding associated with this UME was observed on May 9, 2019 in Cook Inlet. Since then, 134* gray whales have stranded in Alaska. Full or partial necropsy examinations were conducted on a subset of these whales. Preliminary findings from several of the necropsies found evidence of nutritional stress, but other differentials include killer whale predation, marine biotoxins, infectious disease and parasites, human-induced mortality (i.e., vessel strike, entanglement), and contaminants. Recent population assessments show a 38% decline in gray whale abundance that coincides with this UME, from nearly 27,000 gray whales in 2016 to 16,650 gray whales in 2022 (Eguchi et al. 2022a). Additionally, calf counts in 2022 were the lowest on record since monitoring began in 1994 (Eguchi et al. 2022b). The cause of this UME is still under investigation, and is likely a result of several contributing factors. Changes in abundance, distribution, timing of migration, and behavior of gray whales may be indicative of broader ecosystem shifts, such as changes in prey resources in Arctic feeding grounds (Moore et al. 2022). The eastern North Pacific gray whale is considered an “ecosystem sentinel” for North Pacific and western arctic ecosystems (Moore 2008). Considering the rapidly changing conditions in Alaskan waters, this UME may consequently be of special significance.
*As of 10/20/22
Alaska Marine Science Symposium 2023 237
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