| Popis: |
A new life table is compiled for the northern fur seal, Callorhinus ursinus, of the Pribilof Islands, Alaska. The population is assumed to be reasonably stable on the basis of (1) similar estimates for pup production in the late nineteen-seventies, after the apparent low of 1969–1970, and in 1963 when the herd reduction program ended; (2) little variation in the annual commercial harvest of males on St. Paul Island during the late nineteen-seventies; and (3) passage through the population structure by 1980 of most of the delayed effects of commercial sealing on females during 1956–1963. Age specific survival and abundance estimates indicate a total population of approximately 1.25 million animals, including 326 000 newborn pups or 26% of the total. Estimates of population biomass and mean body weight of an individual seal, both near 1 June and including newborn fetuses, are 29 100 mt and 33 kg, respectively. |
