THE ROLE OF PREDATION IN THE ECOLOGY OF THE RINGED SEAL IN BARROW STRAIT, NORTHWEST-TERRITORIES, CANADA

Predation on ringed seals (Phoca hispida) was examined in Barrow Strait between March and May 1984 to 1986. Polar bears were the most important predator. Evidence of bear predation was observed at 18-30% of the ringed seal subnivean structures we located. Ten to 24% of predation attempts were successful, with pups making up 75% to 100% of the seals killed. Bears killed an average of 0.08 to 0.51 seals/km2, which comprised 8 to 44% of the estimated annual pup production. Bears were successful on average in 11.3% of their attempts to kill pups hidden inside birth lairs. On southeast Baffin Island where snow was soft and pups were exposed, bears were successful in 33.5% of their attempts to kill a seal. Negative correlations were found between mean snow depth and predation by polar bears (r = -0.896, P = 0.04, n = 5) in 1985, and between snow depth and the number of predation attempts (r = -0.613, P = 0.02, n = 14) in 1986.