The California Sea Lion is smaller and darker than the Steller Sea lion. Adult males are about 2 – 2.5 meters (6.5 – 8 ft) long and weigh 200 – 200 kg (450 – 900 lbs). Pups weigh about 8 kg (18 lbs) at birth and may nurse for up to a year. The pelage is usually dark brown and appears almost black when wet. Mature males deelop a patch of light coloured fur on the crest of their heads.
The number of California Sea Lions wintering off southern Vancouver Island has grown dramatically in recent years. Prior to the 1960's this species was rarely seen here, but by the early 1970's about 500 were present. Numbers increased to about 1,500 by the early 1980's, peaking at 4,500 in 1984. Numbers have since stabilized at about 3,000. The expansioin of the California Sea Lions into B.C. is probably a result of the recovery of the breeding population off California. The warm El Nino currents in the early 1980's and the recovery of the local herring stocks may also have attracted more animals to B.C. California Sea Lions wintering off southern Vancouver Island mix extensively with Steller Sea Lions. The impact on fisheries here is thus being examined for both species combined. The number of Steller Sea Lions wintering off southern Vancouver Island has increased slightly from about 700 in the early 1970's to about 1,200 currently. It is unclear whether this increase represents a redistribution of Steller Sea Lions that breed on local rookeries or whether Steller Sea Lions are being displaced northward from California and Oregon by the expanding poulation of California Sea Lions.
The increase in number of sea lions wintering off southern Vancouver Island raised many concerns about their impact on local salmon and herring fisheries. Between 1982 and 1985 DFO collected extensive data on the abundance, distribution and feeding habits of these animals. Preliminary analysis of tehse data indicate that the wintering popiulation feeds mainly on schooling fishes such as herring, pollock and dogfish. Herring make up about 35 per cent of the diet and approximately 2,400 tonnes are consumed annually. This represents about 15 per cent of the average annual roe herring harvest off Vancouver Island in recent years. Salmon comprise about 10 per cent of the diet and 600 tonnes are consumed annualy, representing less than 1 per cent of the commercial salmon landings in B.C.
Behaviour and Biology
Only adult and sub-adult male California Sea Lions occur in B. C., mainly during winter months. Between May and August most animals congregate on rookeries off the coast of California and Mexico to mate and pup. At the end of the breeding season animals leave the rookeries. Females and juveniles remain in Calfornia and Mexico during the non-breeding season. Adult and subadult males tend to travel north, venturing as far north as central Vancouver Island. They arrive in B. C. in September – October and depart April – May.
There are three populations of California Sea Lions: the largest population numbers about 120,000 and breeds off the coasts of California and Mexico; another population of 20,000 to 50,000 breeds on the Galapogos Islands; and a small population, perhaps now extinct, was known to breed off Japan. Large kills off California and Mexico during the 1800's depleted that population and reduced its range. However, the population has been increasing since the turn of the century and may now be approaching historic levels.
Research on diving depths for this species during the breeding season on San Miquel Island in California has shown that it can dive to depths of 274 m, with the majority of dives less than 80 m, and lasting less than 3 minutes (longest recorded: 9.9 minutes) (Feldkamp et al 1989).
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:
2020-06-03 7:05:03 AM]
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