Factors affecting the distribution and abundance of ringed seal structures in Barrow Strait, Northwest Territories

Abstract

The relationship between the distribution of ringed seals, Phoca hispida, and habitat was examined in Barrow Strait, Northwest Territories. Density of seal breathing holes was used as an index of seal abundance. Birth lairs were associated with the largest snowdrifts. Lair formation can occur within 24 h after a snowdrift forms over the top of a breathing hole. Seal structures were associated with ridges consisting of ice pieces 15–25 cm thick projecting upwards to a height of 80–150 cm. In 1975 and 1986, the combination of date of ice consolidation and snow depth were the most important habitat features affecting the distribution of ringed seals structures. This was also true with respect to distribution of birth lairs and undefined haul-out lairs, but no relationship was identified between density of structures used by males and habitat. Snow cover and date of ice consolidation were not identified as important habitat variables in 1984 and 1985 when overall distribution of ice in Barrow Strait was very different. Birth lairs were not seen before 4 April, but were found in increasing frequency as the season progressed. Male structures were evident in late March, but were not found after mid-May.