Comparative Health Assessments of Alaskan Ice Seals

Abstract

Bearded (Erignathus barbatus), ringed (Pusa hispida), spotted (Phoca largha), and ribbon (Histriophoca fasciata) seals rely on seasonal sea-ice in Arctic and sub-Arctic regions. Many aspects of the biology and physiology of these seals are poorly known, and species-typical health parameters are not available for all species. Such information has proven difficult to obtain due to the challenges of studying Arctic seals in the wild and their minimal historic representation in aquaria. Here, we combine diagnostic information gathered between 2000 and 2017 from free-ranging seals, seals in short-term rehabilitation, and seals living in long-term human care to evaluate and compare key health parameters. For individuals in apparent good health, hematology, and blood chemistry values are reported by the source group for 10 bearded, 13 ringed, 73 spotted, and 81 ribbon seals from Alaskan waters. For a smaller set of individuals handled during veterinary or necropsy procedures, the presence of parasites and pathogens is described, as well as exposure to a variety of infectious diseases known to affect marine mammals and/or humans, with positive titers observed for Brucella, Leptospira, avian influenza, herpesvirus PhHV-1, and morbillivirus. These data provide initial baseline parameters for hematology, serum chemistries, and other species-level indicators of health that can be used to assess the condition of individual seals, inform monitoring and management efforts, and guide directed research efforts for Alaskan populations of ice-associated seals.

Blood plasma chemistry in White Sea bearded seals across different age groups

“…Age-related changes in mineral metabolism indices in bearded seals are similar to those found in other mammals, both marine (Bossart et al 2001;Goertz et al 2019) and terrestrial (Boyd 1984;Maksimov et al, 2014). In our study, the levels of calcium, magnesium and sodium in the blood plasma of seals are similar across the different age groups (Table 1).…”

“…There is still practically no data in the literature on the metabolic characteristics of these animals as revealed by haematological studies: even in the relevant section of the CRC Handbook of Marine Mammal Medicine: Health, Disease, and Rehabilitation (Bossart et al 2001), the bearded seal is not mentioned. Only recently has data on the blood composition of bearded seals from Alaska been published in connection with marine animal health assessment (Goertz et al 2019). In a guidebook to Russian marine mammals (Burdin et al 2009), it is noted that no studies specifically devoted to bearded seals have been carried out in Russia.…”

Serum biochemistry and haematology in wild and captive bearded seals (Erignathus barbatus) from Svalbard, Norway

“…Haematology data on bearded seals is in general very limited; however, two studies report haematology parameters from wild bearded seals from the Chukchi Sea and Bering Sea [ 19 , 20 ]. Compared to the values reported in these studies, the values for haematocrit (HCT), haemoglobin (Hb/HGB), and mean corpuscular haemoglobin concentration (MCHC) for the four captive adult bearded seals in our study were within the same range.…”

A Review of Circumpolar Arctic Marine Mammal Health—A Call to Action in a Time of Rapid Environmental Change

“…In a longitudinal study sampling harbour seals in southeast Alaska from 1976–1999, 46% were found to have antibodies to Brucella with antibody prevalence increasing with age [ 93 ]. Similarly, Brucella was isolated from bearded seals in Svalbard and Alaska [ 83 , 94 ] and in Baltic ringed seals [ 95 ], and anti- Brucella antibodies have been detected in Atlantic walruses [ 75 , 96 ]. In cetaceans, antibodies for Brucella have been found in minke whales (8 %) and fin whales (11%) [ 90 ].…”