Abstract
Bearded (Erignathus barbatus), ringed (Pusa hispida), and spotted seals (Phoca largha) are Arctic and sub-Arctic pinnipeds that rely on seasonal sea ice for key life history stages, including pupping and molting.1 Recent unusual mortality events (UMEs) involving skin pathology in Alaskan pinnipeds highlight the potential sensitivity of these species to the complex effects of climate change, as well as the lack of available reference data for healthy individuals. The Alaska Pinniped UME (2011–2016) included seals and walruses that presented with abnormal behavior, disrupted molts, and unusual skin lesions.2 Despite intensive investigation, the etiology remains unknown.3 In 2018, there was an increase in seals presenting with similar symptoms and a new UME was declared.4
Thyroid hormones,5-10 vitamin A,9 and cortisol,7,10 have been shown to play essential roles in skin health and seasonal molt in other pinnipeds. Unfortunately, it was not possible to evaluate these factors in cases associated with the UME since no comparative levels were available from healthy animals. To better understand health parameters that may inform conservation and management efforts, diagnostic information was gathered between 2000 and 2022 from Alaskan ice seals in short-term rehabilitation and those living in long-term human care. Thyroid hormones (TT4, TT3, and FT4), vitamin A, and cortisol levels are reported for 5 ringed (42 samples), 6 spotted (46 samples), and 4 bearded seals (6 samples) at the Alaska SeaLife Center including samples taken from the same individuals throughout the year. In general, observed ranges for the target parameters were higher than seen in harbor seals. There were differences between individuals as well as seasons, with peak values observed in late spring during the annual molting period. The information reported in this study, although limited by sample size and sampling intervals, can be used to support veterinary management of Alaskan ice seals under human care. These values establish an initial baseline for skin health monitoring in wild populations and in stranded individuals with known skin lesions or pathology. As more data become available, we hope to resolve seasonal, physiological, and clinical patterns in these important health parameters.
Acknowledgments
The authors wish to thank the staff of the Alaska SeaLife Center for their contributions to this study and their everyday efforts towards animal care and welfare. This study is based on findings and samples obtained under ASLC’s Program of Veterinary Care during routine veterinary and husbandry procedures. Animals in this study are covered by NOAA SA-AKR-2019-01, NOAA/NMFS marine mammal research permits 18902 and 23554, and NOAA MMPA/ESA 18786-04.
*Presenting author
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