Steller Sea Lion (Eumetopias Jubatus)
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- Lists of Figures and Appendices
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status
- Summary of Status Report
- Technical Summary
- Acknowledgements and Literature Cited
- Biographical Summaries of the Report Writers, Authorities Consulted, and Collections Examined
Special Significance of the Species
Once considered vermin, the Steller sea lion is emerging as one of the most intensely studied marine mammals in the North Pacific, and is viewed by many as a symbol of a healthy marine ecosystem.
In 1991, the BC provincial government established the Conservation Data Centre (CDC) to list and track endangered and sensitive wildlife and ecosystems in BC. Since 1992, the CDC has maintained a red list for flagging species that may be threatened and endangered, and the blue list for vulnerable species. The Steller sea lion was red listed when the list was created, primarily on the basis of there being only three major breeding areas in BC, the total population numbering only about 10 000, and the lack of recovery of since the population culls (Cannings et al. 1999).
The Steller sea lion is the largest species of otariid and the only one that resides year-round and breeds in Canadian waters. With the recent declines in Alaska, the BC rookeries at the Scott Islands and Cape St. James now represent the 2nd and 6th largest breeding aggregations in the world. Based on overall pup production in 2002, BC supports about 16% of the world’s population and about 33% of the eastern stock (and another 31% occurs in southeast Alaska within 25 km of the Canadian border). The Steller sea lion is widely regarded as an important component of the coastal marine ecosystem, and contributes to a burgeoning eco-tourism industry.
The role of Steller sea lions as a perceived threat to fisheries warrants mention. Over 50 000 Steller sea lions were destroyed and one breeding area eradicated in BC purportedly to protect the salmon fishery. The recovery of populations since they were protected in 1970 has renewed concerns over their impact on fish stocks and lobbies for control programs. Nevertheless, there is little evidence that Steller sea lion control programs had any beneficial effect on fisheries. Spalding (1964b) noted that salmon catches did not increase noticeably following the reduction of sea lion numbers on the Scott Islands. Indeed, the general understanding of the role of seals and sea lions in marine ecosystems remains poorly understood (Beverton 1985; Bowen 1997; Merrick 1997; Trites 1997). This is not to say that sea lions do not play an important role, but rather that our understanding of these large and complex ecosystems is presently inadequate. Surprisingly, basic knowledge of feeding habits of Steller sea lions in BC are still lacking, and much of the information that does exist has been collected anecdotally as part of other studies.
The Steller sea lion may have potential for serving as an indicator of the general status of inshore marine ecosystems. The species is widely distributed in coastal waters, has a long lifespan, congregates on rookeries where breeding populations can be readily censused, and occupies a position near the top of the marine food chain. One lesson that might be drawn from the recent declines in Steller sea lion populations in western Alaska, which are now widely believed to be the associated with broader ecosystem processes that are not understood, is that the ability to monitor Steller sea lion populations far exceeds our understanding of the ecological processes that regulate these apex predators. As populations in BC and neighbouring waters have now recovered to historic high levels, we might expect natural population regulatory mechanisms to assume an increasingly important role, and the potential for using Steller sea lions as an indicator species warrants further examination.
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