Publications

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resource partitioning between pacific walruses and bearded seals in the alaska arctic and sub-arctic.climate-mediated changes in the phenology of arctic sea ice and primary production may alter benthic food webs that sustain populations of pacific walruses (odobenus rosmarus divergens) and bearded seals (erignathus barbatus). interspecific resource competition could place an additional strain on ice-associated marine mammals already facing loss of sea ice habitat. using fatty acid (fa) profiles, fa trophic markers, and fa stable carbon isotope analyses, we found that walruses and bearded seals ...201728550467
occurrence and genotypic analysis of trichinella species in alaska marine-associated mammals of the bering and chukchi seas.the zoonotic parasite trichinella is the causative agent of trichinellosis outbreaks in the circumpolar arctic. subsistence communities are particularly prone to trichinellosis due to traditional meat preparation methods and regional presence of a freeze-tolerant trichinella species (trichinella nativa). this study is the first application of a validated artificial digestion method in determining incidence of trichinella sp. in alaskan mammals. infection incidence in pinniped species (erignathus ...201424373515
137cs and 210po in pacific walrus and bearded seal from st. lawrence island, alaska.the activity concentration of cesium-137 ((137)cs) and naturally-occurring polonium-210 ((210)po) were measured in the muscle tissue, kidney and liver of pacific walrus (odobenus rosmarus divergens) and bearded seal (erignathus barbatus) collected by native hunters from the bering sea during may 1996. the mean (137)cs concentrations in muscle, liver and kidney of pacific walrus were 0.07, 0.09 and 0.07 bq kg(-1) (n=5, wet weight), respectively, and 0.17, 0.10, and 0.17 bq kg(-1) (n=2, wet weight ...200818371988
viral and bacterial serology of free-ranging pacific walrus.serum or heparinized plasma samples were obtained between 1994 and 1996 from 20 male and 20 female adult free-ranging pacific walrus (odobenus rosmarus divergens) from st. lawrence island and round island, alaska. samples were screened for antibodies to some potentially pathogenic bacteria and viruses. no sample had detectable antibody to brucella spp. three of 40 (8%) had low antibody titers to leptospira interrogans serovars. phocine distemper virus antibodies were not detected. serologic resp ...200211838234
twenty years of trace metal analyses of marine mammals in alaska: evaluation and summation.the compilation of existing data on contaminants in the marine food chain is essential in addressing concerns regarding the magnitude of potential human exposures and in the evaluation of subsistence food safety. this paper presents a summary of studies on trace metals in tissues of alaska marine mammals from the 1970s to the present, along with derived mean tissue trace metal concentrations. the derived mean can serve as a norm against which future monitoring results may be compared, and may be ...199810093345
pulmonary mast cell tumor and possible paraganglioma in a free-ranging pacific walrus ( odobenus rosmarus divergens), barrow, alaska, usa.we describe a pulmonary mast cell tumor in a subsistence-harvested free-ranging pacific walrus (odobenus rosmarus divergens). neoplastic cells effacing a focal area of pulmonary parenchyma were characterized by rare metachromatic granules and positive staining for c-kit. we also report co-occurrence of a peribronchial mass with a morphologic and immunohistochemical profile compatible with paraganglioma.201627054472
underwater passive acoustic localization of pacific walruses in the northeastern chukchi sea.this paper develops and applies a linearized bayesian localization algorithm based on acoustic arrival times of marine mammal vocalizations at spatially-separated receivers which provides three-dimensional (3d) location estimates with rigorous uncertainty analysis. to properly account for uncertainty in receiver parameters (3d hydrophone locations and synchronization times) and environmental parameters (water depth and sound-speed correction), these quantities are treated as unknowns constrained ...201323968051
estimating age ratios and size of pacific walrus herds on coastal haulouts using video imaging.during arctic summers, sea ice provides resting habitat for pacific walruses as it drifts over foraging areas in the eastern chukchi sea. climate-driven reductions in sea ice have recently created ice-free conditions in the chukchi sea by late summer causing walruses to rest at coastal haulouts along the chukotka and alaska coasts, which provides an opportunity to study walruses at relatively accessible locations. walrus age can be determined from the ratio of tusk length to snout dimensions. we ...201323936106
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