Science Advisory Report 2021/035

Trends in Abundance and Distribution of Steller Sea Lions (Eumetopias Jubatus) in Canada

Summary

• Fisheries and Oceans Canada (DFO) has conducted 14 breeding season aerial surveys since the early 1970s to monitor the Steller sea lion population in British Columbia (BC). Surveys are timed to provide counts of both pups and non-pups (juveniles and adults).
• DFO has also conducted periodic fall and winter aerial surveys to examine seasonal changes in adundance and distribution of Steller sea lions overwintering in BC.
• In 2017 a total of 6,640 pups and 25,113 non-pups were counted. Models fit to the counts indicate a possible slowing in the annual rate of growth in pup production since 2013, but not in the rate of growth in the non-pup component of the population.
• An estimate of the total population size was obtained by applying a correction factor to non-pup counts to account for animals that were at sea and missed during surveys. The adjusted 2017 breeding season population estimate was 43,200 (95% CI of 38,700 to 48,200) suggesting no significant change from the previous assessment.
• The winter survey in 2017 provided an estimate of 52,700 (95% CI 41,000 to 67,800) Steller sea lions wintering in the coastal waters of BC. Larger numbers of sea lions estimated from winter surveys compared to breeding season surveys appear to be due to a net influx of animals from rookeries outside of BC.
• The number of rookeries and year-round haulout sites continues to increase in BC waters.
• The Potential Biological Removal (PBR) for Steller sea lions during the summer breeding season is 2,474 for Canadian waters.

This Science Advisory Report is from the February 17-22, 2020 National Marine Mammal Peer Review on Steller Sea Lion Population Abundance Estimate. Additional publications from these meetings will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2021/035 (PDF, 946 KB)

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