Steller sea lion (Eumetopias jubatus) management plan: chapter 6

Executive Summary

The Steller Sea Lion is the largest member of eared seals and a relatively long-lived and slow reproducing species. The scientific name (Eumetopias jubatus) means having a broad forehead and a mane, a reference to the prominent ruff of coarse hair that mature males develop on their necks and chests which resembles a lion’s mane.

All sea lions are remarkably agile on land due to their ability to rotate their hind flippers forward and prop themselves up on their foreflippers. Steller Sea Lions can climb steep rocks and are often found many metres above the sea surface; they tend to be highly gregarious while on land and pack close together in dense breeding colonies (rookeries) or on non-breeding haulouts. Steller Sea Lions typically haul out on a regular basis, they sometimes spend many days or several weeks at sea without coming ashore and can sleep in the water, usually in groups called rafts. 

This species is trans-boundary in its distribution and research and management are currently conducted by Canadian and U.S. governments, as well as private organizations and independent researchers. There are four active breeding sites within British Columbia, one of which has recently been re-established after having been eradicated by predator control programs in the 1920s. The Scott Islands rookery is now the second largest breeding aggregation in the world, and B.C. currently supports approximately 33% of the total Eastern Population of Steller Sea Lion. Steller Sea Lions in B.C. are currently breeding at all known historic rookeries, and populations have grown well past known peak historic levels. 

Based on estimated pup production during the last range-wide survey in 2002, the total size of the Eastern Population is estimated to between 46,000 to 58,000 animals. Abundance in Canadian waters was estimated to be 20,000-28,000 based on the most recent survey in 2006 (DFO 2008). During breeding season, the congregation of animals at the four Canadian breeding sites makes the B.C. population vulnerable to human disturbance and catastrophic events, which has the potential to affect a significant proportion of the population.

Limiting factors are the natural processes that limit population size or growth, whereas threats (both natural and anthropogenic) have caused, are causing, or may cause harm, death or behavioural changes to a species at risk or the destruction, degradation and/or impairment of its habitat to the extent that population-level effects occur. Steller Sea Lions are limited by bottom-up processes that affect prey availability and accessibility, and by top-down processes that affect predation rates. The most significant threats identified for Steller Sea Lions are competition with fisheries, and environmental variability limiting prey availability. Toxic spills and chronic chemical contamination are also of moderate concern for long-term impacts to population health. Further research will assist in clarifying these threats.

Steller Sea Lions in Canada are listed under the Species at Risk Act as ‘special concern’ meaning they are considered a wildlife species that could become threatened or endangered because of a combination of biological characteristics and identified threats. This management plan has two goals. First, to ensure that anthropogenic threats from Canadian sources do not cause unsustainable population declines, contraction of current range or number of breeding sites in Canada. A second goal of this plan is to encourage support for, and contribution to an environment where research and monitoring of Steller Sea Lions in B.C. contributes to achieving an improved global knowledge of the Eastern Pacific Population. Six high priority actions have been identified to address the threats of greatest concern (Table 3), and 20 ongoing actions beneficial to conservation and understanding of the species are also listed. Six additional actions are listed to identify new efforts useful for management of the population. Participation of interested parties in listed actions is encouraged and will contribute to implementation of this plan and conservation of this species in Canada. Synchronization of activities recommended for protection, management and research will facilitate a multi-species approach to marine mammal conservation in B.C., and allow for effective use of available resources.

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