Steller Sea Lions | Watch Marine Mammals at Fort Ross

Physical Characteristics

First described in 1751, the Steller Sea Lion is named for naturalist George Wilhelm Steller, a German naturalist serving on a Russian expedition. The largest member of eared seal family, and adult male Steller Sea Lion reaches 9-12 feet in length and weighs up to 2,500 pounds. Their size, along with a large, muscular neck and thick mane, differentiate the males from females, who are generally two to three times smaller than the male Steller Sea Lion. These sea lions have a uniformly blond or reddish coat that holds its color when wet and lightens with age. Molting of the fur takes place annually – in spring or summer for females and in later months for males.
Steller Sea Lions at Fort Ross, by Joe Mortenson

Fort Ross Steller Sea Lion Rock – map and photos

Breeding

Steller Sea Lions typically range from Southern California to Japan, with the Aleutian Islands as the main breeding center. Breeding season, the peak abundance for these sea lions on shore, occurs from the middle of June into early July. During this time, males fast to keep in defense of semiaquatic territories up to 20 feet in diameter and guard up to 30 females. Although males become sexually mature between ages 3-8, they rarely are large enough to defend territories before the age of nine or ten. While the nursing of the pups usually lasts 32-44 weeks, females have been known to arrive for breeding with the previous year’s pup, nursing the newborn and older at the same time.
Feeding and Behavior

Steller Sea Lions generally stay between the coast and the continental shelf but have been seen as far as 300 miles from shore. While their main diet consists of many fish and squid, they also eat crustaceans and mammals like harbor seals and sea otters. Steller Sea Lions are generally considered non-migratory, though they have been known to travel long distances to find prey; males often hunt alone, whereas females and young form small foraging groups.

Population Threats and Conservation

Entering the endangered species list, the Steller Sea Lion population has declined steadily since the 1940’s, with a decline as large as 50%. These sea lions have been hunted for food, hides, blubber, fur, and more recently to reduce competition with fisheries. Although protective zones of 20 mile buffers around haul out sites have been designated for their critical habitat, the population is thought to be still declining, possibly due to overfishing. Other threats to the species include pollutants, interaction with fishing gear, and the continuation of hunting despite illegality.

Main Sources:

Allen, Sarah G., Joseph Mortenson, and Sophie Webb. “Steller Sea Lion.” Field Guide to Marine Mammals of the Pacific Coast: Baja, California, Oregon, Washington, British Columbia. Berkeley: University of California, 2011. 392-403. Print.

“Steller Sea Lion (Eumetopias Jubatas).” NOAA Fisheries Office of Protected Resources. N.p., 11 June 2013. Web. 07 Oct. 2013.