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

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 fo...

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Bibliographic Details
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:
Online Access:http://dx.doi.org/10.1139/f85-063
http://www.nrcresearchpress.com/doi/pdf/10.1139/f85-063
Description
Summary: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.