RE-ESTIMATING THE SIZE OF THE POLAR BEAR POPULATION IN WESTERN HUDSON-BAY

A mark-recapture study of polar bears (Ursus maritimus) ashore during the ice-free period of Hudson Bay was undertaken in 1994 and 1995 to r e-estimate the size of the western Hudson Bay population. Previous est imates were based on animals caught between the Churchill and Nelson R ivers; consequently, bears in the southern part of the geographic rang e of this population were not sampled. We used Jolly-Seber models to r e-estimate population size from two data sets: bears handled between t he Churchill and Ne!son Rivers from 1984 to 1995 and bears handled bet ween Churchill and the Manitoba-Ontario border from 1984 to 1995. The latter sample incorporated mark-recapture data collected along the eas tern Manitoba coast by the Ontario Ministry of Natural Resources from 1984 to 1986 and by us in 1994 and 1995. Both data sets gave similar e stimates. Thus, our best estimate of the size of the western Hudson Ba y polar bear population is 1200 +/- 250 animals in autumn 1995.