Temporal Changes in the Reproductive Potential of Female Harp Seals ( Pagophilus groenlandicus )

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Bowen, W. Don, Capstick, Charles K., Sergeant, David E.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1981
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Harp Seal; Northwest Atlantic; Pagophilus groenlandicus
• Online Access: http://dx.doi.org/10.1139/f81-071; http://www.nrcresearchpress.com/doi/pdf/10.1139/f81-071

The Northwest Atlantic harp seal (Pagophilus groenlandicus) population declined by more than 50% between 1952 and the early 1970s. Biological sampling of female reproductive tracts began in 1951 and has continued to the present. We reexamined the extent to which mean age of maturity and fertility rate have changed as population size declined. Mean age of maturity declined from ~ 6.2 yr in 1952 to 4.5 yr in 1979. During this same period fertility rate increased from 85 to 94%. Both parameters have changed concurrently with a decline in numbers. Although it is likely that density-dependent mechanisms are involved, empirical data are lacking.Key words: harp seals, Pagophilus groenlandicus; maturity, fertility, density-dependence