Steller Sea Lions (Eumetopias Jubatus) are the largest of the eared seals. They are divided into two distinct populations namely “western” and “eastern.” The population of the western stock has seen an alarming decline in the last 50 years, with numbers dropping from around 240 000 to 45 000. They are listed as endangered by both the IUCN as well as under the US Endangered Species Act. The exact cause of their decline is debatable, though indications point to reduced food source due to over-fishing. Despite their endangered listings, these animals continue to be illegally shot by fishermen and the extent by which these animals were affected by the 1997-1998 el Nino is unknown. Oil spills, chemical pollutants, disease and loss of habitat are all factors which are contributing to their demise.
Breeding for Steller Sea Lions takes place from mid May through till mid July. As with may pinnipeds, males are usually the first to arrive on the scene. They appear to have a natural affinity to certain spots, and will return to the same place each year to stake their claim. They will maintain their breeding territories for over a month, during which time they do not eat at all.
Females arrive shortly afterwards and will give birth to a single pup two or three days later. The mother will remain with her pup for the first 10 days or so before leaving to forage. Foraging trips last between 1 and 3 days at after which she will return to land to nurse and suckle her young for 1-2 days. Weening usually takes around a year, though some records have shown that pups as old a three are still suckling from the teat. Females do not always give birth with each successive year.
Pups, which are born with a dark coat that lightens as the animal matures, weigh in at an average of 17-22kg and measure +/- 1m in length. Females become sexually mature at an age of between 3-7years while males mature at between 4-8years. Territorial breeding for males is only achieved when the animal is much older though, usually at between 10-12 years. Male Steller Sea Lions live till they are around 20 though females live considerably longer, almost to 30.
Although Steller Sea Lions feed mostly off a diet of squid, octopus and fish, observers have reported this species feeding on juvenile Northern Fur Seals as well as adult Harbour Seals and Ringed Seals.
This species is preyed upon by sharks and killer whales, while on land predation from Arctic Foxes has been known to occur.
Steller Sea Lions get their name from the German Naturalist, George Wilhelm Steller, who was the first person to study these animals scientifically as far back as 1742.
Steller Sea Lions are extremely vocal. As one scientist put it, “They are forever yelling at each other.” Pups are able to locate their mothers out of thousands by the sounds she makes. Between bulls roaring, mothers barking and pups bleating, rookeries are a very noisy place indeed!
These Sea Lions can hold their breath for up to 40 minutes, and when avoiding predators such as Orca’s, they can manage bursts of speed up to 40km/h.
They are extremely intelligent and can be taught to perform natural behaviour on cue. While we (The Seals Of Nam) are personally against animals in captivity, it is interesting to note that these animals, along with Californian Sea Lions, have been trained for military purposes too.
Aside from being hunted for their fur, blubber, oil and meat, some strange people have even gone so far as to use the whiskers (vibissae) of these animals as pipe cleaners!
A Steller Sea Lion will eat on average 6% of its total body weight each day.
It is difficult to study these animals in the wild as they are skittish and tend to bolt when humans are around.
The deepest dive recorded for a Steller Sea Lion is 424 meters!