Estimation of Harp Seal ( Phoca groenlandica ) Pup Production from Age Samples

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Author: Cooke, Justin G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1985
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Harp Seal; Northwest Atlantic; Phoca groenlandica
• Online Access: http://dx.doi.org/10.1139/f85-063; http://www.nrcresearchpress.com/doi/pdf/10.1139/f85-063

A simple numerical example shows that previously used procedures such as the "survival index" method for estimating the pup production in populations of harp seals (Phoca groenlandica) from samples of aged adults are unreliable because of their poor mathematical formulation. A corrected formulation, based on a maximum likelihood criterion, performed well in simulations tests. This was applied to age data from the Northwest Atlantic harp seal stock to obtain revised pup production estimates. A method to correct for the effects of errors in ageing also performed favourably in simulation trials.