Arctic | Mammals
Harbor porpoise strandings on the North Slope, Alaska 1952-2021 Presenter: Raphaela Stimmelmayr , rafstimmel@gmail.com, North Slope Borough Perry Anashugak , perry.anashugak@north-slope.org, NSB DWM Frances Olemaun , frances.olemaun@north-slope.org, NSB DWM Rita Acker , rita.acker@north-slope.org, North Slope Borough, Department of Wildlife Management
Few studies have documented harbor porpoise ( Phocena phocena ) presence and mortality north of the Bering Strait. Stranding records are a valuable source of information for marine mammal habitat use and mortality factors. We analyzed stranding reports (n=35) of Harbor porpoises on the North Slope from 1952-2021. Strandings were observed along the shore line of the Chukchi sea (17 %), in Elson Lagoon (71 %), and in 2 rivers (11 %). Annual stranding cases ranging from 0-7 were highly variable with high numbers being reported in 1987 (4;11%), 1991 (7; 20%), 1993 (5;14%), 1994 (3;9%) 2020 (3;9%) and 2021 (3;9 %). Strandings were observed during the month of July to August, with most observations being reported during August (91%). Fisheries interaction (71 %) was the leading cause of death (COD), blunt and sharp trauma (vessel strike) with each 5.9%, subsistence harvest (3 %) and 14.7 % where COD could not be determined. Age composition was 30 adults (86 %) and five neonates (14.3 %). Blunt trauma to the head (2/4) was the leading COD for neonates. Incidental findings in harbor porpoises that underwent complete necropsy by a veterinarian (n=7) included parasitic infections of the respiratory (lung worms), hepatic (liver flukes), digestive (anisakis; tape worms), and integumentary system (crassicauda spp.), anatomical variation (accessory spleens), and circular skin lesions of unknown etiology in one animal. Observations of bycaught harbor porpoises up North have been reported as early as 1952 and our data suggest that bycatch remains an important mortality factor for harbor porpoises during their time up North. Based on spatial and temporal distribution of recent neonate stranding records (n=4; 2013-2021) we suggest that the coastal area near Utqiagvik to Wainwright is an important calving area with births occurring within a narrow time window (July 29-August 13). Abundant sperm presence in an adult male stranded during mid August is supportive of a summer mating season.
Alaska Marine Science Symposium 2023 275
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