The Stellar sea lion, aka Stellar’s sea lion or northern sea lion, is a large sea lion species that can be found from northwestern U.S., western Canada, on over to east Asia and Japan. As pinnipeds go, only the walrus and the 2 elephant seal species outsize them. These sea lions face the threats of overfishing; bycatch – getting caught in longlines and gill nets; habitat loss and destruction at the hands of residential and commercial developments; ecosystem modifications; and climate change, that affects their habitat via sea storms that alter their habitats. These sea lions are listed as Near Threatened by the IUCN.
First the Stats…
Scientific name: Eumetopias jubatus
Weight: Up to 2,470 lbs.
Length: Up to 10.7 feet
Lifespan: Up to 30 years
Now on to the Facts!
1.) There were an estimated 81,327 wild individuals remaining as of 2016. However, that number is slowly increasing.
2.) Like all sea lions, they are sexually dimorphic (males and females look markedly different). The males are much larger than females and also possess a thick mane of coarse hair around their neck.
3.) The oldest known fossil records date back to the later part of the Early Pleistocene, approximately 800,000 years ago, and were found near Kanazawa, Japan.
4.) Usually, Steller sea lions spend a fair amount of time in the water feeding yet haul-out onto land to reproduce, raise their pups, molt, and sleep.
5.) They prefer to haul out along the beaches of remote islands, as it is safer, quieter, and there is more prey available, with less predators and/or human disturbances.
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6.) Their primary prey items include, but are not limited to pollock, mackerel, halibut, herring, capelin, flatfish, cod, rockfish, sculpins, salmon, sand lance, and cephalopods like a variety of squid and octopus species.
7.) A great deal of the data on their foraging comes from information collected off the coast of Alaska. Not much is known of their foraging in other locations.
Did you know…?
Their Latin name literally translates to “maned one with the broad forehead”.
8.) These critters have also been known to prey on northern fur seals, harbor seals, and sea otter pups.
9.) They are, in turn, preyed on by orcas, great whites, and sleeper sharks.
10.) The larger, older males set up and defend distinct territories on a preferred rookery. A week or so afterwards, adult females arrive, occasionally followed by sexually immature offspring, and develop fluid aggregations in the rookery.
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11.) Steller sea lions, like all otariids (eared seals), are polygynous (1 male mates with multiple females).
12.) These critters do not form harems, but rather the males control a spatial territory where females come and go freely.
Did you know…?
Even though males are typically tolerant of pups, 1 male filmed on Medny Island in Russia was documented killing and eating numerous pups in a first-ever recorded incident of cannibalism. While the motive of that individual remains uncertain, it is believed that the individual was experiencing psychosis.
13.) Males with semiaquatic territories tend to have the most success in defending them. The boundaries are typically defined by natural features, such as faults, ridges in rocks, and/or boulders, and territories can stay stable for up to 60 days.
14.) Copulation typically occurs 1 – 2 weeks after giving birth, however, the fertilized egg does not become implanted in the uterus until the fall. This is known as delayed implantation.
15.) Females undergo up to an 11.5 month gestation (pregnancy) that yields up to 2 pups. However, a single pup is much more common.
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16.) After about a week or more of nursing without leaving the rookery, females will start to make progressively longer and more frequent foraging trips leaving their pups behind until late summer. Then both the mother and her pup(s) leave the rookery together.
17.) In a study conducted by the University of California, Santa Cruz it was discovered that, on average, male pups drink more milk than females.
Did you know…?
These sea lions can swim at speeds of up to 1.5 body lengths per second!
18.) Weaning varies dramatically, and pups may stay with their mothers for up to 4 years before becoming fully independent.
19.) Another study done at Año Nuevo in 1983 discovered that female attendance and the time spent with their pup(s) was dictated by the increasing nutritional demands of the pup(s) and the pup’s suckling effectiveness.
20.) Females averaged up to 21 hours ashore and 36 hours at sea. As the pup(s) got older, the females started to spend more time at sea. As the pup(s) matured, primarily at the 6th week after birth, the mother’s sea time was reduced by up to 30%.
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21.) In order to be able to dive for long periods of time, these critters display apnea (the stopping of breathing), bradycardia (the reduction in heartbeats), and peripheral vasoconstriction (the narrowing of blood vessels in the skin and organs). This provides them with the ability to maximize their oxygen stores and efficiently forage longer during their dives.
22.) Communication consists of a range of vocalizations as part of their territorial behaviors. Sounds such as belches, growls, hisses, and snorts serve as warnings to others.
Did you know…?
Sonogram readings detailed these sea lions producing discrete, low frequency pulses underwater that sound like the male “belching” territorial noise made on land. These underwater vocalizations have an average of 20 – 30 pulses per second.
23.) Both males and females produce underwater noises that are similar to their above water sounds, and are described as barks, belches, and clicks.
24.) Vocalizations are crucial to mother-pup pairs, as this is how mothers find their pups in a crowded breeding rookery when they return from foraging.
25.) Steller sea lions have been traditionally hunted for meat and other materials by prehistoric peoples everywhere their range intersected with humans. Aside from food and clothing, their skin was also used to cover baidarkas and kayaks. A subsistence harvest in the estimated amount of 300 animals or less continues currently in some native communities in Alaska.
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26.) During the 19th century their whiskers were sold for a penny apiece and used as tobacco-pipe cleaners.
27.) Fortunately, in October 2013, the eastern Steller sea lion was removed from the U.S. Endangered Species List after major population spikes over the past several years.
28.) Killing sea lions is strictly forbidden in the United States and Russia; however, in Japan, a certain number are still harvested each year, primarily to protect their fisheries.
29.) While the populations of the eastern and Asian Steller sea lions seems to be stable, the populations of the western Stellars, primarily along the Aleutian Islands, was estimated to have dropped by up to 80% since the 1970s! A suspected cause of their rapid decline was the overfishing of Alaska pollock, herring, and other fish species in the Gulf of Alaska.
Now a Short Stellar Sea Lion Video!
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Some source material acquired from: Wikipedia & IUCN
Photo credit: Anne Morkill
