Science Advisory Report 2020/046

Status of Steller Sea Lions (Eumetopias jubatus) in Canada

Summary

• Fisheries and Oceans Canada (DFO) has conducted 13 province-wide aerial surveys since the early 1970s to monitor the Steller sea lion population in B.C. Surveys are timed to coincide with the end of the breeding season so as to provide an estimate of pup production, as well as counts of juveniles and adults (non-pups).
• During the most recent survey in 2013, a total of 28,452 sea lions were counted in B.C. This included 6,317 pups and 22,135 non-pups (10,969 on rookeries and 11,166 on non-breeding haulout sites). This compares to a total of 23,514 sea lions counted in 2010, including 5,485 pups and 18,029 non-pups. The counts from aerial surveys represent minimum abundance because some pups may have died and older animals foraging at sea would be missed.
• An estimate of the total population size during the 2013 breeding season of 39,200 (95% CI of 33,600 to 44,800) was obtained by applying a correction factor based on telemetry data to account for animals that were at sea and missed during surveys. There is evidence for a continued increasing trend from the 2010 estimate of 32,500 (95% CI 28,200-36,800) although the Confidence Intervals (CI) overlap.
• Both pups and non-pups have increased since early 1970s, and population growth appears to be increasing at an accelerating rate. Between 2010 and 2013, the population growth rate for Steller sea lions in B.C. pups was 5.64% and non-pups 4.55%. However, there is uncertainty around the degree of immigration from neighboring US rookeries and the contribution to the abundance and growth of the B.C. population.
• The number of rookeries and year-round haulout sites has increased in B.C. waters since the species was first protected in 1970. In addition to the recovery of the previously eradicated rookeries on the Sea Otter Group by 2006, new rookeries have been established since that time at Garcin Rocks, Gosling Rocks and off Bonilla Island.
• Abundance of Steller sea lions has also increased in recent years at neighboring rookeries in SE Alaska, Washington and Oregon, as has the number of rookeries and year-round haulouts. 
• The most recent winter surveys in 2009-2010 indicated that an estimated 48,500 (95% CI 38,100 to 58,900) Steller sea lions winter in the coastal waters of B.C. The increase in abundance during the non-breeding season appears to be due to a net influx of animals from rookeries outside of B.C. 

This Science Advisory Report is from the October 20–24, 2014 Annual Meeting of the National Marine Mammal Peer Review Committee (NMMPRC). Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Scheduleas they become available.

Science Advisory Report 2020/046 (PDF, 1,319 KB)

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