Fur Seal Investigations, 1986
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Fur Seal Investigations, 1986
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Fur Seal Investigations, 1986
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    Northern fur seal (Callorhinus ursinus) research in 1986 was conducted on the Prihilof Islands, Alaska, and on San Miguel Island and nearby Castle Rock in southern California. Estimates made of the number of pups bom on St. Paul Island in 1986 (167,656 + 16,272) were not significantly different from the estimated total number bom in 1985 (182,258 + 18,887). The estimated fractions of sheared animals determined from photographs and actual field counts (shear ing-sairpling method) taken during 1986 are not significantly different from each other. Pelagic studies during 1986 were restricted to an analysis of feeding data collected near the Pribilof Islands during 1985. Studies showed that key predatory fish and fur seals consumed walleye pollock (Theraara chalcogramma) as a major dietary component. It was estimated that fur seals consumed as much pollock (132.5 x 103t) as walleye pollock did preying on pollock (134 x 103t). Currently the population of the San Miguel Island fur seal colony appears to be slowly increasing and has now reached numbers observed in the late 1970's. The decline was associated with the 1983 El Nino event which brought about a 60% decline in pup production and a 48% decrease in numbers of adult females. In 1986 670 pups were bom and a maximum female count was422 or 65% and 67% of the 1982 values, respectively. On Castle Rock, a count of 576 pups represented an increase in pup production of 78.3% more pups than the 1985 count of 323 pups.
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