Pup Production Following Harvest of Female Northern Fur Seals

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: York, Anne E., Hartley, James R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1981
• Subjects: Callorhinus ursinus; Northern fur seal
• Online Access: http://dx.doi.org/10.1139/f81-011; http://www.nrcresearchpress.com/doi/pdf/10.1139/f81-011

Female northern fur seals (Callorhinus ursinus) were harvested commercially from 1956 to 1968 and pelagic collections were taken for research purposes from 1958 to 1974. Early survival rates (birth to age 2) for males increased from an average of 0.32 before the harvest to 0.38 afterwards. Numbers of female pups whose births were precluded by the harvest are estimated for the years 1956–79; these account for about 70% of the difference between the numbers of pups actually born and the level of pup births before 1956. Estimates of the increased numbers of pups due to the increase in the early survival rates are presented for the years 1958–74.Key words: northern fur seal, population dynamics, female harvest, cohort analysis, St. Paul Island