The Aquatic Furry Mammal: Steller Sea Lion


Introduction & Physical Appearance

Steller or northern sea lions are sometimes confused with California sea lions, but are much larger and lighter in color. Males may grow to 11 feet (3.25 m) in length and weigh almost 2,500 pounds (1120 kg). Females are much smaller and may grow to nine feet (2.9 m) in length and weigh 1,000 pounds (350 kg). Steller sea lions are light tan to reddish brown in color. They have a blunt face and a boxy, bear-like head. Adult males do not have a visible sagittal crest (the bump on the top of their heads) as is seen in adult male California sea lions. Adult male Stellers have a bulky build and a very thick neck with longer fur that resembles a lion's mane, hence the name "sea lion."


Steller sea lions are found in coastal waters of the North Pacific Ocean from Japan to central California. Breeding occurs along the North Pacific Rim from Año Nuevo Island in central California to the Kuril Islands north of Japan, with the greatest concentration of rookeries (breeding grounds) in the Gulf of Alaska and Aleutian Islands. Steller sea lions eat a variety of fishes, invertebrates, and occasionally other pinnipeds. Known predators are killer whales (orcas) and white sharks.



Reproduction

Pups typically are born on islands from mid-May to mid-July and weigh 35-50 pounds (16-23 kg). Mothers stay with pups for one to two weeks before hunting at sea. During the breeding season, mothers spend roughly equal amounts of time hunting and nursing pups on land and gradually spend more time at-sea as nursing pups get older. Pups usually nurse for a year, but some continue to nurse for up to three years. Mating occurs 10-14 days after the pups are born. Dominant mature males maintain territories for one to two months and mate with many females. During the breeding season, males do not eat.



List of Threats

Threats to Steller sea lions include:

  • Boat / ship strikes

  • Contaminants/ pollutants

  • Habitat degradation

  • Illegal hunting/ shooting

  • Offshore oil and gas exploration

  • Interactions (direct and indirect) with fisheries

  • Direct fishing impacts are largely due to fishing gear (drift and set gillnets, longlines, trawls, etc.) that has the potential to entangle, hook, injure, or kill sea lions. They have been seen entangled in fishing equipment with what are considered "serious injuries."

  • Indirect fisheries impacts include having to compete for food resources and possible modifications to critical habitat by fishing activities


Interaction with Humans

Historically, Steller sea lions were hunted for their meat, fur, and oil; this played a part in the decrease of their population. Incidental population destruction has also occurred due to fishing nets, ship strikes, pollutants and diseases.


Steller sea lions are thought to deplete fish stocks and eat fish out of hatcheries, so they are often killed or hunted.


Watch "Steller Sea Lions: Grizzlies of the Sea: SALISH SEA WILD: EPISODE ONE": https://www.seadocsociety.org/steller-sea-lions



Conservation Efforts

The species was listed as threatened under the federal Endangered Species Act in 1990. A recovery plan was developed for the Steller sea lion in 1992 that designated critical habitat for the species as a 20 nautical mile buffer around all major haul-outs and rookeries along with three major foraging sites. A revised recovery plan was issued in 2008, which discussed separate recovery action plans for both subspecies.

In 2013, the eastern subspecies of the Steller sea lion was delisted due to the successful recovery of the eastern populations, having been estimated to increase 243% over the last 40 years due to the conservation benefits and protection provided by Endangered Species Act. However, the western subspecies of Steller sea Lions in the United States has been listed as Endangered since 1997.



Sourced From/More Information:

Images & Article 1: https://www.marinemammalcenter.org/education/marine-mammal-information/pinnipeds/steller-sea-lion/

Article 2: https://animaldiversity.org/accounts/Eumetopias_jubatus/#economic_importance_positive

Article 3: https://lpfw.org/our-region/wildlife/steller-sea-lion/

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