Gerald W. Garner

Seasonal movements of adult female polar bears in the Bering and Chukchi seas

Ten adult female polar bears (Ursus maritimus) were fitted with satellite telemetry collars during March 1986 in the Kotzebue Sound area ofthe Chukchi Sea. During March-April 1987,2 of these bears were refitted with satellite telemetry collars and an additional 10 adult females were collared in the northern Bering and eastern Chukchi seas. Data for 1,560 point locations recorded through May 1988 indicated that female polar bears in the Bering and Chukchi seas were resident in western Alaskan waters from November through March, then moved northward with the receding pack ice during April and May. They remained in the northern and northwestern Chukchi Sea during June through September, often adjacent to the Soviet coastline. Satellite telemetry data indicated that 4 females marked in Alaskan waters ofthe Chukchi Sea apparently denned in the vicinity of Wrangel Island during winter 1987/1988. Denning in American territory of bears marked in the Chukchi and Bering seas has not been documented using satellite telemetry data. Some polar bears moved from the Chukchi Sea into the western Beaufort Sea during summer and fall, then returned to the Chukchi and Bering seas the following winter. Movements of bears from the Chukchi Sea into the central or eastern Beaufort Sea were not documented through spring 1988. These data document that polar bears occurring in the Bering and Chukchi seas are shared internationally between the United States and the Soviet Union. Int. Conf. Bear Res. and Manage. 8:219-226 Polar bears are circumpolar in their distribution and were once believed to be circumpolar wanderers (Pederson 1945, as cited in Lentfer 1983). Currently, it is thought that there are 6 distinct populations of polar bears in the polar basin (DeMaster and Stirling 1981) and tagging data indicate limited exchange of individuals between these hypothesized populations (Taylor 1982). Movement information during the 1970s was primarily limited to mark/recapture data (Sch weinsburg et al. 1982(2, Lentfer 1983). Use of conventional radio-telemetry was first used during the late 1970s and became more com? mon during the 1980s (Amstrup 1986a, Calvert et al. 1986). However in northern Alaska, the cost and size of the area surveyed limited the number of locations per marked bear to 3-6 locations per year (S.C. Amstrup,

Serosurvey of selected zoonotic agents in polar bears (Ursus maritimus)

Between 1982 and 1999 blood samples were collected from 500 polar bears (Ursus maritimus) captured in the Beaufort and Chukchi seas, to determine the seroprevalence of Brucella species, Toxoplasma gondii, and Trichinella species infections. The bears were classified into four age groups, cubs, yearlings, subadults and adults. Brucella and Toxoplasma antibodies were detected by agglutination (a buffered acidified card antigen and rapid automated presumptive test for brucellosis and a commercial latex agglutination test for toxoplasmosis); an ELISA was used to detect Trichinella antibodies. The overall seroprevalence of Brucella species was 5 per cent, and subadults and yearlings were 2˙62 times (95 per cent confidence interval 1˙02 to 6˙82) more likely to be seropositive for Brucella species than adults and their cubs. The antibody prevalence for Toxoplasma gondii was 6 per cent, and for Trichinella species 55˙6 per cent. The prevalence of antibodies to Trichinella species increased with age (P<0˙001).

Serological evidence of morbillivirus infection in polar bears (Ursus maritimus) from Alaska and Russia

One-hundred-and-ninety-one samples of blood serum collected from 186 polar bears (Ursus maritimus) between 1987 and 1992 were analysed for morbillivirus antibodies. The samples were collected in the Bering, Chukchi and East Siberian seas. Sixty-eight samples (35.6 per cent) had morbillivirus antibody titres >5; the percentage of positive samples ranged from 26.2 to 46.2 per cent from year to year. The proportions of adults, sub-adults and cubs which were seropositive were 43.9, 35.7 and 37.9 per cent respectively. Some seropositive dams had seronegative young and some that were seronegative had seropositive young. One litter of two cubs, in which the dam was seronegative, had one seropositive and one seronegative cub. Seropositive bears occurred in all the areas from which the samples were collected but there was a significantly greater incidence in the bears sampled in Russia. The high prevalence of seropositive bears over the period suggests that the bear morbillivirus is endemic in these regions of the Arctic, but its source is unknown.