Arctic | Mammals
Incidence of found dead polar bears and causes of death on the North Slope, Alaska 2001- 2022 Presenter: Raphaela Stimmelmayr , rafstimmel@gmail.com, North Slope Borough Carla SimsKoyatuk , SimsKoyatuk@north-slope.org, NSB DWM David Rotstein , drdrot@gmail.com, Marine Mammal Pathology Services Billy Adams , billy.adams@north-slope.org, North Slope Borough Dept. of Wildlife Management Understanding health and mortality in free-ranging polar bears is important for stock management. We retrospectively evaluated reports (field observations; necropsy reports) from 39 found dead polar bears on the North Slope, Alaska between 2001 to 2022 to characterize spatial and temporal distribution, demographics and identify causes of morbidity and mortality. COD was broadly classified as infectious, nutritional, toxin, traumatic (human interaction (HI); non -HI), and CBD (could not be determined). Annual reports ranging from 0-6 were highly variable with high numbers being reported in 2004 (10.26 %), 2006 (7.7%), 2012 (15.4%), 2016 (12.8%) and 2018 (7.7%). Geographic distribution of polar bear carcasses included coastal areas and barrier islands and extended between Prudhoe Bay (70.2268° N, 148.4012° W) to Icy Cape (70.3297° N, 161.8742° W). The majority was found in the Beaufort Sea (22/39; 56.4%) compared with the Chukchi Sea (16/39; 41%). Most carcasses were found by Inupiaq hunters while traveling on the land or ocean (56.4%), followed by biologists (28.2%), and industry (12.8%). Though carcass observations occurred throughout the year, most carcasses were found during summer (41%) and fall (33.3%). The remaining carcasses were found during winter and spring, 5.1% and 7.7% respectively. For 12.8 % information was not available. Carcass distribution was 48.7% on land, 18 % surf/beachcast and 23 % floating. Of the cases with known carcass condition (67%) distribution was fresh (15.1%), moderate (35.9%), advanced (5.4%), and skeletal (10.3%). Sex identification was not available for 53.9% of the carcasses. For the remaining carcasses (46.2%) sex composition was equal between males and females. Though all age classes were represented, subadults and adults together made up 64.1% and cubs/yearlings 26%. Cause of death (COD) could not be determined (CBD) for 38.46 % of the mortalities. For the remaining cases, COD was due to trauma (28.2%), emaciation (7.7%), presumed drowning (12.8%), toxins (5.1%), and infection (5.1%). This study establishes a baseline for understanding causes of mortality in found dead polar bears.
Alaska Marine Science Symposium 2023 276
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