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Seal & Walrus Health Studies

NSB-DWM Bearded Seal and Walrus Health Assessment

Principal Investigators Raphaela Stimmelmayr
Collaborators Veterinary student Greta Krafsur, Dr. Terry Spraker (Colorado State University); Graduate students Jill-Marie Seymour and Sara Carroll, Dr. Lara Dehn (UAF)
Funding NSB, ADFG, CSU, UAF. CIAP funds to be available soon

Summary:

As part of the NSB-DWM marine mammal health research program to establish baseline information about our subsistence species, hunters allow collection of samples from their subsistence hunted bearded seal and walrus. In 2008 and 2009, Greta Krafsur, a veterinary student at Colorado State University, carried out this work with help from DWM personnel and graduate students from the University of Alaska Fairbanks. The majority of samples collected she collected were from the villages of Wainwright and Barrow. We are now beginning to receive results from the analysis of many of these samples (see the preliminary reports below). Starting in 2011, Raphaela Stimmelmayr, research biologist and wildlife veterinarian for NSB-DWM, continued this work. Subsistence harvested animals are aged, sexed, and have body measurements taken. In addition, samples from organs and blood from each animal are taken. If you would like to participate in this health assessment, contact Raphaela Stimmelmayr or call 852-0350.

Preliminary Reports:

Krafsur found that the seal and walrus samples that were collected in Wainwright showed that the animals were in “good overall health and excellent body condition.” Having access to freshly hunted animals from local subsistence hunters provided her with high quality tissues, making her observations very valuable. Her assessments of these normal tissues provide baseline information which can be used for comparison with future possible impacts, such as the effects of “diminishing sea ice, increased water temperatures, ship traffic, and industrial development.”

Abstract:

Tissue samples from subsistence harvested bearded seals (Erignathus barbatus) and walruses (Odobenus rosmarus divergens) were collected in the coastal village of Wainwright, Alaska in June 2009. Tissues were collected from 12 bearded seals and 5 walruses for routine histological examination. One seal had pyogranulomatous panniculitis, likely caused by a bite wound. Exertional rhabdomyolysis was a common histological finding in seven of twelve seals and three of five walruses. One tissue cyst resembling T. gondii was identified in the tongue skeletal muscle of one seal. Sarcocysts were identified in the skeletal muscles of eight of twelve bearded seals, but not in walrus. There were no histopathological renal lesions suggestive of Leptospira spp infection. Loss of sea ice, warmer temperatures, increased ship traffic and oil and gas activity make disease surveillance of marine mammal populations that are important subsistence resources for Alaska’s indigenous coastal populations a high priority for scientists working with the North Slope Department of Wildlife Management in Barrow, Alaska.

  • Seal-Eating Walrus

The following poster presentation outlines the examination of a subsistence-harvested walrus that was found with a ringed seal in its stomach. The examination was performed by North Slope Borough Department of Wildlife Management staff, and laboratory analyses were conducted at the School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, and Colorado State University School of Veterinary Medicine.

Incidental Gross Necropsy Findings in Subsistence-Harvested Ice Seals and Walruses

  • Stimmelmayr, Raphaela, et al. 2014. Incidental gross necropsy findings in subsistence-harvested ice seals and walruses. Poster presented at the Alaska Marine Science Symposium, Anchorage, Alaska, January 2014.

Other Seal and Walrus Studies

Pacific Walrus Feeding Study (UAF)

Pacific walrus mostly feed on benthic invertebrates, like clams. “It has been suggested that in situations of nutritional stress or during unfavorable ice conditions walruses may prey on other pinnipeds.” Seymour et al. used the analysis of stable carbon and nitrogen isotopes to determine that found that 20% of Pacific walrus diets included higher trophic level organisms, like seals. The other 80% of the diet is made up of benthic invertebrates. Their findings are consistent with TEK of walrus feeding on seals. This percentage of seals in walrus diets is “higher than the historical 10% and could suggest climatic impacts on walrus foraging brought on by changes in sea ice quality and extent.” However, their methods of analysis are different from the historical method of observing stomach contents, which favors the finding of hard-bodied invertebrates. This could mean that walrus typically take seals when they are available. The sampled walrus with the higher trophic level isotope signature were males.

Publications:

  • Seymour, J., Horstmann-Dehn, L., and Wooller, M.J. 2014. Inter-annual variability in the proportional contribution of higher trophic levels to the diet of Pacific walruses. Polar Biology DOI 10.1007/s00300-014-1460-7.
  • Seymour, J., Horstmann-Dehn, L., and Wooller, M.J. 2014. Proportion of higher trophic-level prey in the diet of Pacific walruses (Odobenus rosmarus divergens). Polar Biology DOI 10.1007/s00300-014-1492-z.

Oil Fouling of Ice Seals

The poster below was presented at the 2014 Alaska Marine Science Symposium, by Gay Sheffield et al., regarding 3 oil-fouled ice seals found in the Bering Strait area in 2012. Seabirds were found oiled from a spill of unknown origin at the same time. For more information, contact Raphaela Stimmelmayr.

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