Steller’s Sea Lion
Eumetopias jubatusSteller’s sea lion was once considered a pest because of the quantities offish it “stole “from humans. Now the situation has been reversed; Steller’s sea lions are in decline because we eat too much of their food. Although it is a widespread species, the number of Steller’s sea lions has been declining since the 1980s, when there were about 290,000; today there are fewer than 89,000. The western population, which extends across the Aleutian Islands to Japan, appears to be shrinking relatively slowly. The main losses seem to have occurred in the eastern population along the coasts of California, Oregon, British Columbia, and southern Alaska. Although the population there may still number about 39,000, it has declined by 83 percent in 30 years. If an animal population decreases that fast, action must be taken before it is too late.
Steller’s sea lion used to be hunted for its meat, hide, and blubber, but commercial hunting stopped in the 1970s. About 400 are still killed each year for traditional uses by the indigenous peoples of Alaska (the skins make good canoe covers). Marine mammals in American waters have full legal protection, so large scale killing of Steller’s sea lions or disturbance of their breeding places should be prevented now and is unlikely to be the main cause of their decline. However, the animals are sometimes caught up in fishing nets. Around Vancouver Island licenses were issued to kill a few sea lions that were causing problems in fish-farming areas, and some illegal killing still goes on. Oil spills and contamination of food by chemicals pose another threat to Steller’s sea lion, as they do to many other species. Around Japan high levels of tributyl tin (TBT) have been reported in the bodies of sea lions. This is a poisonous substance found in the paint used to prevent barnacles from attaching to the hulls of boats. Despite such hazards, the basic problem for Steller’s sea lion seems to be a reduction in its food supply. The animals feed on fish, which they catch on or near the seabed, sometimes diving down to more than 1,200 feet (400 m) to get them. Trawlers harvest the same fish by dragging huge nets across the seabed. This competition for fish is a problem for the sea lions, especially around sea lion breeding colonies, where mother sea lions feed for up to three days at a time before returning to suckle their pups on the beaches.
Action against Fishing
Intensive commercial fishing has left fish stocks-especially walleye pollock severely depleted. Trawlers were banned from fishing near sea lion breeding places throughout the 1990s. Exclusion zones were then extended to keep trawlers at least 22 miles (35 km) away from the colonies, and fishing restrictions were imposed all year round, not just in the breeding season. Fishermen were also made to spread their activities to reduce the pressure on fish stocks in certain areas. Around the Aleutian Islands, for instance, restrictions were placed on fishing for mackerel (another important food for the sea lions), and trawling for pollock was forbidden. Such measures have come about partly as a result of lobbying by environmental campaigners. They must be taken seriously in order for us to prevent unpredictable and possibly irreversible damage to the North Pacific ecosystem and the extinction of Steller’s sea lion.
Steller’s sea lion (northern sea lion)
Eumetopias jubatus
- Family: Otariidae
- World population: Fewer than 89,000
- Distribution: Edges of North Pacific and Bering Sea male 1,240-2,470 lb (566-1,120 kg); female 580-770 lb (263-350 kg)
- Form: Seal with coat of short, coarse hair; small ears; longer flippers than true seals. Males have manes
- Habitat: Coastal waters, offshore rocks and islands; also sea caves
- Diet: Fish, particularly pollock, salmon, herring, mackerel; sometimes squid and octopus
- Size: Length: male 9.2-10.5 ft (2.8-3.2 m); female 7.5-9.5 ft (2.3-2.9 m). Weight:
- Breeding: Single pup born per year after 12-month gestation. Mature at about 4 years. Life span over 30 years in females, lower in males
- Related endangered species: Guadeloupe fur seal (Arctocephalus townsendii); Galapagos fur seal (A. galapagoensis); Juan Fernandez fur seal (A. philippii); northern fur seal (Callorhinus ursinus); Hooker’s sea lion (Phocarctos hookeri)
