Northern Sea Lion or Steller's Sea Lion

Common Name: Steller's Sea Lion

Class: Mammalia

Order: Pinnipedia

Family: Otariidae

Genus: Eumetopias

Species: Eumetopias jubatus

 

Taxonomy/Description

Steller's sea lions belong to the Mammalian Order Pinnipedia, in the family Otariidae.  Other members of Otariidae include all species of fur seals and sea lions.  Otariids are easily distinguishable from other pinnipeds by their external ear flaps.  Steller's sea lion's scientific name is Eumetopias jubatus, which means "having a mane and large forehead".  This animal is named for George Wilhelm Steller (1709-1746), a German zoologist who explored the coastal areas of the northern Pacific Ocean in 1740.

Steller's sea lion is one of the heaviest pinnipeds, outsized only by elephant seals and walruses.  Males may grow 10-13ft in length and 1800-2000 lbs in weight.  Females grow to about 8ft and 600 lbs.  The average life span is about 20 years.  At first glance, Steller's sea lions appear very similar to California sea lions.  However, differences do exist.  Their fur is a lighter color than the California sea lion, light tawny brown.  Steller sea lion males do not have a saggital crest on their forehead and they have a blunter nose than California sea lion males.  The vocalizations of each species are also different.  California sea lions produce a honking bark, while Steller's sea lions release a deeper growl.  Like all sea lions, mature males have a mane, their large necks and shoulders covered with long hair.

Habitat/Diet

Steller's sea lions are found in the Bering Sea surrounding the Aleutian Islands, throughout the Asian coast to northern Japan and down the American coast to southern California.  Steller's sea lions eat squid, octopus, salmon, other fish, and fur seal pups.

Behavior/Reproduction

Males establish harems during the breeding season.  These harems include 10-15 females located on a territory under control by the male.  The male will defend his territory and harem for two months, and during these two months he will not eat.  Females give birth around June or July.  They breed again very soon after birth.  Delayed implantation of the fertilized egg prevents the pup from being born until the next birthing season.  Weaning age varies but is generally one year.

Conservation

The population of Steller's sea lions in Alaska has declined 50% from the 1970's to the 1980's.  This species was considered threatened in the 1990's, and is now considered endangered.  Although the California sea lion is thriving, the Steller's sea lion's numbers are steadily falling.  Suspected causes for their decline include overfishing and pollution.  However, it is still odd that the California sea lion is thriving while Steller's sea lion is declining.

 

Content provided by Canisius College students under the direction of Michael Noonan, PhD.