Recent Trends in the Abundance of Harbour Seals,Phoca vitulina, in British Columbia

Abstract

Aerial censuses of harbour seals (Phoca vitulina) were conducted in the Strait of Georgia (1966-68), the lower Skeena River (1977-87), off the southwest coast of Vancouver Island (1976-87), off the northeast coast of the Queen Charlotte Islands (1986), in Jervis Inlet (1987), and at the entrance to Queen Charlotte Strait (1988). The estimated number of seals in the Strait of Georgia, the primary study area, increased from 2170 in 1973 to 15,810 in 1988; the number in the lower Skeena River from 520 in 1977 to 1590 in 1987; and the number off southwestern Vancouver Island from 210 in 1976 to 1130 in 1987. The trends indicated that populations throughout British Columbia had been increasing at a rate of about 12.5% .cntdot. yr-1 since 1973. Based on the density of seals in the areas surveyed, and the relative distribution of bounty and commercial kills, the total post-pupping population in British Columbia was estimated to have numbered 75,000-88,000 in 1988, compared with 9000-10,500 when the species was protected in 1970. Despite the recent increases, which probably reflect the recovery from historic kills, there was no evidence of density-dependent changes in the population growth rate.