Eumetopias jubatus

Pelage, which lacks underfur, is tawny, yellowish brown, or reddish brown in adults (may appear to be darker when fur is wet), dark brown to blackish in pups; small external ears are present; all limbs are flipperlike, and the hind limbs can be turned forward and used in terrestrial locomotion. Adult males have long, coarse hair on the chest, shoulders, and back; the chest and neck are massive and muscular (Hall 1981, Nowak 1991). Newborn pups have a thick, dark-brown coat that molts to lighter brown after 6 months (Daniel 2003).

Steller sea lions are the largest otariid. Males grow larger than females. The average standard length is 282 cm in adult males and 228 cm in adult females (maximum of about 325 cm and 290 cm, respectively); weight of males averages 566 kg and females 263 kg (maximum of about 1,120 kg and 350 kg) (Fiscus 1961, Calkins and Pitcher 1982, Loughlin and Nelson 1986, Winship et al. 2001). Newborn pups are about 1 meter long and weigh 16-23 kg (Daniel 2003).

This species differs from the California sea lion in larger adult size (average male Stellar sea lion is about 282 cm and 566 kg; average male California sea lion is about 250 cm and 400 kg), paler pelage, absence of a protruding crest on the forehead of adult males, and presence of a large diastema between the fourth and fifth upper postcanine teeth.

Marine habitats include coastal waters near shore and over the continental slope; sometimes rivers are ascended in pursuit of prey. When not on land, the sea lions may congregate at nearshore traditional rafting sites, or move out to the edge of the continental shelf (Kajimura and Loughlin 1988, Sea Lion Recovery Plan Team 1991). While offshore, the sea lions are most often found within 35 km of shore (Kenyon and Rice 1961, Fiscus and Baines 1966, Fiscus et al. 1976, Bonnell et al. 1983) but may range out to several hundred kilometers offshore. The distance sea lions move offshore varies seasonally, with fewer animals being sighted at sea during the summer (Fiscus et al. 1976, Bonnell et al. 1983). Waters extending 0.9 km from rookeries (and major haulouts) were determined to be essential habitat by the Recovery Team (see NMFS 1993); these waters, plus an air zone extending 0.9 km above a rookery/major haulout and (in Alaska) a land zone extending 0.9 km landward from a rookery/major haulout are included in critical habitat designations.

The most commonly used terrestrial habitat types are rookeries and haulouts. Rookeries are areas where adults congregate for breeding and pupping. These habitats generally occur on beaches of remote islands with difficult access for humans and other mammalian predators (Sea Lion Recovery Plan Team 1991). The beaches can be sand, gravel, cobble, boulder, or bedrock. Female sea lions tend to select locations for pupping that are gently sloping and protected from waves (Sandegren 1970). Females often use the same pupping site in successive years and tend to breed in or near their natal colony (Calkins and Pitcher 1982). Rookery sites may be used as haulout sites during the nonbreeding season. Independent juveniles usually avoid rookeries (Gentry 1970, Sandegren 1970, Calkins and Pitcher 1983, Hoover 1988). From about two weeks after birth, the pups begin to spend increasing amounts of time in the intertidal areas and swimming near shore. Haulouts are areas used by adult sea lions during the nonbreeding season and by nonbreeding adults and subadults throughout the year (Sea Lion Recovery Plan Team 1991). Haulout locations include exposed rocks, reefs, beaches, jetties, breakwaters, navigational aids, floating docks, and sea ice. Selection of both rookery and haulout sites appears to depend on a number of factors including substrate type, degree of exposure to wind and waves, proximity to food resources, tradition of use, season, and the degree of human disturbance (Gentry 1970, Sandegren 1970, Calkins and Pitcher 1983, Hoover 1988, Johnson et al. 1989).

Predators include orcas (killer whales) and sharks.

The life cycle includes several basic stages, minimally including recently born pups, dependent juveniles, independent juveniles, subadults, and adults.

Females give birth to single pups a few days after arriving at the rookery, late May to early July (mainly late June). Females mate with territorial males within 2 weeks of parturition; mating occurs June to mid-July. Implantation is delayed 3-4 months; total gestation period is about 1 year. Female stays with her pup for 3-13 days, then begins a series of 1-2-day feeding trips that extend over a period of several weeks, during which time the pup is left ashore. Young are weaned usually within 1 year in California; lactation usually lasts more than 1 year in Alaska. Females are sexually mature in 3-4 years (or up to 8 years); may breed into their early 20s (Mathisen et al. 1962, Pitcher and Calkins 1981); most adult females breed annually, though a high rate of reproductive failure results in a lower than 100 percent birth rate among adult females (estimated at 55-63 percent by Pitcher and Calkins 1981 and Calkins and Goodwin 1988). Males attain sexual maturity at 3-7 years old (Pitcher and Calkins 1981), but breeding (territorial) males typically are at least 7-8 years old (most often 9-13 years old in Alaska) (Thorsteinson and Lensink 1962, Loughlin et al. 1987, Raum-Suryan et al. 2002). Males may live up to around 20 years and females to around 30 years.