Steller sea lion  Eumetopias jubatus

Steller sea lions, also known as Northern sea lions, are the largest of the eared seals, sometimes reaching ten feet in length and 2,500 pounds. They are light brown to blond with dark flippers. Hundreds of sea lions are known to congregate at rookery sites that have been used for generations. They use these sites for resting and mating.

Steller sea lions are endangered but appear to be recovering, with population numbers increasing each year.

Range

Steller sea lions prefer cold waters and live in the Northern Pacific Ocean from California to Japan.  Large males and sub-adult Steller sea lions can occasionally be seen in the inland waters of Washington State.  The best places to view them along The Whale Trail are the San Juan Islands and in the Strait of Juan de Fuca. Occasionally, Steller sea lions are observed hauled out at buoys near Seattle.

Biology

Like other pinnipeds, Steller sea lions have a coat of fur that molts, or sheds, every year.  Both sexes have long whitish whiskers, or vibrissae, on their muzzle. The flippers and other hairless parts of the skin are black.

The fore-flippers are broader and longer than the hind-flippers and are the primary means of locomotion in water.  On land sea lions can turn their hind flippers forward for walking. 

They feed primarily on fish such as rockfish, herring, and greenling.  They also feed on squid, octopus, shrimp, salmon, and other marine species. They have been observed swallowing rocks which biologists believe helps with digestion.

Social Structure and Behavior

Males form a harem at rookeries to establish their territory for breeding seasons. Females arrive and give birth starting in mid-May, mating again only two weeks after giving birth.

  • Females are mature at three to seven years of age but males typically do not breed before the age of 10. 
  • Gestation lasts 10 months with females usually giving birth around late June. 
  • Pups nurse for about a year on average but some have been documented nursing for up to four years. 

Steller sea lions are known for their curiosity and playfulness, sometimes leaping from the water.  They have even been seen jumping across surfacing whales! Sea lions can also be aggressive and will bite if they feel threatened.

Current and Historical Threats

Steller sea lions in Washington State are from the eastern stock which is listed as threatened under the Endangered Species Act.  This stock has been increasing at approximately 3 percent per year since the late 1970s and the current population estimate is 47,885 individuals. 

The 2008 Recovery Plan for Steller Sea Lions reported that no threats to recovery have been identified and the population has been increasing for over 25 years.  New rookeries have been created and the population is at historically high levels. However, they are still endangered.

Learn More!

 Books:

Astro: The Steller Sea Lion by Jeanne Walker Harvey and Shennen Bersani, 2010

Steller Sea Lions (Eye to Eye With Endangered Species) by Precious Stearns, 2009

The Decline of the Steller Sea Lion in Alaskan Waters: Untangling Food Webs and Fishing Nets by Committee on the Alaska Groundfish Fishery and Steller Sea Lions and National Research Council, 2003

Links:

http://animals.nationalgeographic.com/animals/mammals/steller-sea-lion.html

http://www.nmfs.noaa.gov/pr/species/mammals/pinnipeds/stellersealion.htm

 

Sources

Northwest Marine Mammal Stranding Network Handbook Steller sea lion recovery plan http://www.alaskafisheries.noaa.gov/protectedresources/stellers/recovery.htm  

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Facts

Length

Adult ♂ : 10.5 ft (3.2 m)

Adult ♀ : 8.5 ft (2.6 m)

Birth Length :45 in (1.1 m)

Weight

Adult ♂ : 1250 lbs (567 kg)

Adult ♀ : 550 lbs (250 kg)

Birth Weight : 50 lbs (23 kg)

Life Expectancy

18 – 30 years

Photos

The Whale Trail is a nonprofit organization in partnership with
Partners NOAA Seattle Aquarium People for Puget Sound Washington Department of Fish and Wildlife The Whale Museum National Marine Sanctuaries