Steller Sea Lions are the largest members of the Otariidae. Adult males reach 3 m (10 ft) in length and weigh 450 – 1,000 kg (1,000 – 2,200 lbs) whereas the smaller females are 2.4 m (8 ft) long and weigh 180 – 230 kg (400 – 500 lbs). Pups weigh about 20 kg (45 lbs) at birth and may be nursed for more than a year. The life span of males is about 20 years and that of females about 30 years. The pelage consists mainly of coarse guard hairs and is usually tan in colour.
Aerial censuses conducted during the breeding season IN 1987(?) indicate that the population in B.C. was about 7,000 (including 1,100 pups) and had changed little since the mid-1960's. This population number represented only about one third the number present at the turn of the century. The reason for the decline was extensive kills between 1912 and 1968. During that time, DFO staff made annual trips to rookeries and haulouts to kill sea lions for predator control. Adults were also commercially harvested on rookeries for mind food.
Fishers have long been concerned over the impact of Steller Sea Lions on commercially valuable fish stocks. On average, females consume about 5 – 10 kg (11 – 22 lbs) and males 10 – 20 kg (22 - 45 lbs) daily. During the breeding season, Steller Sea Lions feed predominantly on octopus and a variety of fish, mainly rockfish. During the non-breeding season they prey mainly upon schooling fishes such as herring, hake, pollock, dogfish and salmon. Overall, salmon constitutes only a few per cent of their diet.
Behaviour and Biology
During June and July most of the population gathers on rookeries to breed. In B.C., rookeries are situated at Cape St. James, North Danger Rocks and on the Scott Islands. Animals tend to return to the rookery on which they were born. Some adults and juveniles are also found on sites known as year-round haulouts during the breeding season. In late summer and fall individuals on rookeries disperse locally along the coast to numerous wintering sites.
The Steller Sea Lion occurs along the coastal rim of the North Pacific Ocean, from California to the Bering Sea and Kurile Islands. The species tends to remain within a few miles of shore, but is occasionally seen as far as 130 km (80) offshore. Although juveniles have been found up to 1,500 km (900 miles) from their place of birth, adults are largely non-migratory. The total population numbers about 200,000 with most occurring the Gulf of Alaska. However, populations in Alaska have recently been declining inexpicably, and are now only half the size they were in the 1950's.
Globally, Northern or Steller Sea Lions are found in the "coastal waters of the North Pacific from California and northern Honshu, Japan, and Korea, north to the Bering Strait" (BC Species and Ecosystem Explorer 2009). They reside year-round and breed in British Columbia (DFO 2008), where they are found along the entire coast, usually within 45 km of shore (Cannings et al. 1999). Breeding males are territorial, and pup mortality is about 10% (BC Species and Ecosystem Explorer 2009). According to DFO (2008), from 1912-68, Steller sea lions in B.C. "were subject to predator control programs and commercial harvests. A total of 55,000 sea lions were killed during 1912-68, and by the 1970s breeding populations had been reduced to roughly 25-33% of the peak historic levels thought to have been present in the early 1900s".
In 2003, COSEWIC (2003) listed the status of this species as Special Concern, stating that it "..met criterion for Threatened, D2, but designated Special Concern because the population is increasing and there is a possible rescue effect." In a 2008 status assessment update conducted by the Department of Fisheries and Oceans Canada (DFO 2008), it was found that “the abundance of Steller sea lions in B.C. has increased at an overall rate of 3.5% per year since the early 1970s”. DFO (2008) also indicates that “during the most recent survey in 2006, a total of 19,818 sea lions were counted in B.C. This included 4,118 pups and 15,700 non-pups (7,171 on rookeries and 8529 on non-breeding haulout sites)". COSEWIC status presently remains the same. The species is currently blue-listed in British Columbia (BC Species and Ecosystem Explorer 2009).
BC Species and Ecosystems Explorer. 2009. Steller Sea Lion species summary. BC Ministry of Environment, Victoria. Available online.
Cannings, S.G., L.R. Ramsay, D.F. Fraser, and M.A. Fraker. 1999. Rare amphibians, reptiles, and mammals of British Columbia. Wildlife Branch and Resource Inventory Branch, B.C. Minist. Environ., Lands and Parks, Victoria.
COSEWIC. 2003. Steller Sea Lion Information Page. Committee on the Status of Endangered Wildlife in Canada. Available online.
DFO. 2008. Population Assessment: Steller Sea Lion (Eumetopias jubatus). DFO Canadian Science Advisory Secretariat Science Advisory Report 2008/047. Available online.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
15/09/2019 12:29:50 AM]
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