Harbour seals (Phoca vitulina) are found along temperate and Arctic marine coastlines of the Northern Hemisphere. They are found in coastal waters of the northern Atlantic and Pacific Oceans, as well as those of the Baltic and North Seas. In Canada, they may be found off the coastal waters of British Columbia, Nunavut, Manitoba, Ontario, Quebec, New Brunswick, Prince Edward Island, Nova Scotia, and Newfoundland and Labrador.

Population trends and abundance of harbour seals in British Columbia are assessed based on aerial surveys conducted during 1966-2019. Based on counts conducted in Index Areas distributed throughout the province, the trend observed in the Strait of Georgia appears to be generally indicative of harbour seal populations throughout British Columbia. Total abundance of harbour seals on the B.C. coast in 2008 was estimated to be on the order of about 105,000 (95% confidence interval of 90,900 to 118,900) seals. Total abundance was re-estimated in 2022 (estimate and CI pending completion of CSAS process). Historic reconstructions indicate the population was depleted by a period of commercial harvesting during 1879-1914, and subsequently maintained below natural levels by predator control programs until the early 1960s. Already depleted, the population could not sustain a second period of intense commercial harvesting during 1962-1968 and was further depleted, but now appears to have fully recovered.