Demographic Parameters and Harvest-Explicit Population Viability Analysis for Polar Bears in M'Clintock Channel, Nunavut, Canada

Abstract

Polar bear (Ursus maritimus) numbers in M'Clintock Channel, Nunavut, Canada have decreased significantly since 1972. We used mark–recapture and recovery data collected from 348 marked polar bears from 1972 to 2000 to estimate demographic characteristics and harvest risks of the M'Clintock Channel polar bear population. Total (harvested) survival rates (±1 SE) from mark–recapture analysis were: 0.62 (±0.15) for cubs of the year, 0.90 (±0.04) for subadults (ages 1–4 yr), 0.90 (±0.04) for adult (age ≥5 yr) females, and 0.88 (± 0.04) for adult males. Mean litter size was 1.68 ± 0.15 cubs with a mean reproductive interval of 2.8 ± 0.2 years. By 6 years of age, on average 0.29 ± 0.47 females were producing litters; mean litter production rate for females aged >6 years was 0.93 ± 0.33. We estimated total abundance to average 284 ± 59.3 bears, of which 166.9 ± 35.4 individuals were female and 117.2 ± 26.4 were male. We incorporated our standing age and mark–recapture demographic parameters as input into a harvest risk analysis designed to account for demographic, environmental, and sampling uncertainty. Population growth rate was 0.946 ± 0.038 for the period 1993–1999. A harvest quota not exceeding 3 bears/year is required if the population is to increase in the short term. Slightly higher quota options are available if increased risk and recovery times are accepted by stakeholders.