Steller Sea Lion Fact File
Eumetopias jubatus
Credit: Public Domain
Weight
263-1000kg
(580-2204lbs)
Length
3-3.3m
(9.75-11ft)
Lifespan
Wild 20 years
Captive 20 years
Conservation Status
IUCN
Near Threatened
The steller sea lion is the world's largest sea lion and the fourth largest pinniped. Males may be as much as 3 times the size of a female.
They live along the coastline of the Pacific rim with populations congregating at sites known as rookeries where they rest and breed. Feeding takes place out at sea.
Females give birth to a pup on the land and care for it for 7-10 days before returning to the water to feed. She will return once a day to feed the pup which remains on land till it can feed.
The species suffered from large amounts of hunting by fisherman who viewed them as a threat to their catch with a 50% decline in population since 1960. Luckily it appears this trend is beginning to reverse.
Read on to learn more about these marvelous mammals below.
Appearance
What does the Steller sea lion look like?
Steller sea lions are the largest species of sea lion and the fourth largest of the pinniped family. An adult measures between 3 and 3.3m (9.75-11ft) long with a weight of 263-1000kg (580-2204lbs).
Males are significantly larger than females and have a wide muzzle, huge head and a neck which features a distinctive mane. He may be up to three times her size.
Both the male and female are covered in a coat of tawny or buff-colored fur. The flippers are colored black.
When they become wet the lighter coloration on their body does not darken unlike other species of sea lion.
Along with being larger this species can be distinguished from the California sea lion with which it shares part of its range due to the lack of a crest on the head.
On either side of the muzzle are light colored whiskers which can be used to feel where they are going or detect prey when underwater.
Diet
What does the Steller sea lion eat?
The Steller sea lion is a carnivore. Their diet includes a wide variety of aquatic prey including fish, octopus, squid, invertebrates and mammals such as sea otters and smaller seals.
They will congregate near fishing vessels and eat any bycatch which is being discarded.
Credit: Public Domain
Range
Where can you find the Steller sea lion?
Populations of the Steller sea lion are found in coastal areas around the Pacific Rim. Here they can be found in the following countries - Canada; China; Democratic People's Republic of Korea; Republic of Korea; Japan; Russia; United States.
In the United States they occur along the coast of Alaska, Oregon, Washington and California.
Habitat
What kind of environment does the Steller sea lion live in?
Steller sea lions are aquatic animals which hunt in the water and make use of rocky shores along the coast where they can haul out to rest. Most of the feeding takes place near the shore and out to the outer continental shelf but in some areas they cross deeper oceanic water.
In areas where sea ice is present they may haul out on this.
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Reproduction
How does the Steller sea lion produce its young?
Mature individuals will congregate at the breeding sites in May. These sites are known as rookeries. Males will fight one another to claim an area of shore line. These fights can become fierce as they batter their bodies in to one another and bite.
Males spend all their time defending their territory and the females within it, with which he maintains breeding rights. During this time they do not eat. As a result of this and their fighting behavior they often have shorter lives than females.
Younger males occasionally sneak on to the mating ground and are able to mate without the dominant male noticing.
Females give birth during the next mating season following the year long gestation period. At birth pups average 1m (3.3ft) long with a weight of between 18 and 22kg (40 and 49kg).
Pups start out with dark brown or black colored fur which will lighten as they grow. It is fully molted by 6 months of age.
Females remain onshore with the pup for 7-10 days. Following this they will take to the water for up to a full day and then return to nurse the pups.
Two weeks after giving birth the female may mate again and become pregnant with next years pup. A period of delayed implantation occurs and the egg does not begin developing immediately.
Weaning typically occurs before the start of the next breeding season but some continue to drink milk in to their second year of life.
Males are not involved with caring for the pup but do defend the females they mated with.
Sexual maturity will be reached between 3 and 7 years old. Males tend to mature older than females. It may take males a few years after maturity before they grow large enough to defend a territory.
Behavior
What does the Steller sea lion do with its day?
Steller sea lions will go out to sea to hunt and then once they have had their fill they will haul out on a rocky shore to rest.
At sea they tend to forage alone or in a small group with up to 12 members. At rookeries there may be hundreds of individuals.
An average dive lasts two minutes but some have recorded diving for periods of up to 13 minutes. They seem to complete deeper dives during winter.
Their vocalization is a low frequency sound which is likened to a roar.
Credit: Public Domain
Predators and Threats
What is impacting the survival of the Steller sea lion?
The main natural predator of the steller sea lion is the killer whale or orca along with some species of shark. In one part of their range predation of pups by the Arctic fox was recorded.
Previously the largest threat to this species was intentional culling and hunting but this practice was largely discontinued in the 1970s and they are now afforded protection under federal law in the US.
This species was never prized for their pelt in the way that other seals and sea lions were offering them some protection from hunting.
Some become entangled in fishing nets while others are shot by commercial fishermen. They see them as a threat to the fish in their nets as the sea lions will take fish from the net.
Disease may also represent a threat to this species.
Recent estimates of their population have shown a 50% decline since 1960 but signs show this trend is now beginning to reverse.
Quick facts
These animals may also be known as the northern sea lion.
They were named after the German surgeon and naturalist, Georg Wilhelm Steller in 1742 as part of the Bering expedition.
Steller sea lions are the only living member in their genus.
Credit: Public Domain
References
Burnie, D., 2011. Animal. 3rd ed. London: DK
Jackson, T. and Chinery, M., 2012. The illustrated encyclopedia of animals of the world. London: Southwater.
Gelatt, T. & Sweeney, K. 2016. Eumetopias jubatus. The IUCN Red List of Threatened Species 2016: e.T8239A45225749. https://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T8239A45225749.en. Downloaded on 29 September 2021.
Marine Bio. 2021. Steller Sa Lions. [online] Available at: <https://www.marinebio.org/species/steller-sea-lions/eumetopias-jubatus/> [Accessed 29 September 2021].
NOAA. 2021. Steller Sea Lion. [online] Available at: <https://www.fisheries.noaa.gov/species/steller-sea-lion> [Accessed 29 September 2021].
Oceana. 2021. Steller Sea Lion. [online] Available at: <https://oceana.org/marine-life/marine-mammals/steller-sea-lion> [Accessed 29 September 2021].
Pinnipeds.org. 2021. Steller Sea Lion. [online] Available at: <https://www.pinnipeds.org/seal-information/species-information-pages/sea-lions-and-fur-seals/steller-sea-lion> [Accessed 29 September 2021].
Marinemammalcenter.org. 2021. Steller Sea Lion | The Marine Mammal Center. [online] Available at: <https://www.marinemammalcenter.org/animal-care/learn-about-marine-mammals/pinnipeds/steller-sea-lion> [Accessed 29 September 2021].
Keranen, D. 2013. "Eumetopias jubatus" (On-line), Animal Diversity Web. Accessed September 28, 2021 at https://animaldiversity.org/accounts/Eumetopias_jubatus/
NOAA. 2021. Steller Sea Lion. [online] Available at: <https://www.fisheries.noaa.gov/species/steller-sea-lion> [Accessed 29 September 2021].
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