Steller Sea Lions

Steller Sea Lion
Mirror, mirror on the wall, who is largest of them all? Well, if we are talking about sea lions, Steller sea lions are winning this contest.

This threatened species got their name from German scientist, George Steller, who studied and classified them, but there are still many unknown details about these animals. For example, science still has no explanation for the fact that stones are often found in their stomach. Some people believe that the gravel can be used for food processing or even as a “weight” which can help them regulate buoyancy while diving.

They are marine mammals, belonging to the order of Pinnipedia, and they are classified under the name Eumetopias jubatus. They live in the Northern Pacific, and can be found from the coasts of Alaska to Japan and Russian coastal waters, almost always in colonies.

They are large animals, and can weigh up to 1,000-2,500 pounds and are about 10 ft. long (adult males) while females weigh up to 770 pounds and are in average 8.2 ft. long. These beautiful animals can live up to 30 years, but males have a much higher mortality rate. When they reach 10 years, the ratio of female to male lions is 3:1.

Steller Sea LionMale lions become sexually active when they reach 3-7 years, and females reach reproductive age at 3-8 years. They usually have one pup each year and are pregnant for 12 months. On average, they have 3 pups during their life. Mothers stay with their young for 10-14 days before starting to hunt at sea and are able to recognize them by smell. Pups usually leave their moms when they reach juvenile stage, which is 14 months.

Just like other sea lions, they feed on a variety of fish such as salmon, mackerel, herring and capelin, but they are also very fond of octopuses and squids. It is known that sometimes they feed on other Pinnipedia such as baby seals. They hunt at night, almost always close to the shore, and feed in groups, probably because it is easier to control the movement of fish. Male lions can eat about 40 pounds of food per day, and females about 20 pounds.

Although they are not considered migratory, they can swim more than 100 miles, and can dive very deep, even up to 1,000 feet. Usually, a dive lasts for 2 minutes, but they can hold their breath for up to 20 minutes. Around 1,000 individuals can be found in Washington state during peak times, usually hauling out on offshore rocks, jetties and navigation buoys. Near Seattle, divers can see them in the middle of Elliott Bay. Young adults will occasionally come near and investigate scuba divers, playfully chewing on diver’s gear. One of the best dive sites to see them is Alki Seacrest Park (Cove 2) in West Seattle

In Washington, Steller sea lion numbers vary seasonally with peak counts of 1,000 animals present during the fall and winter months. Haulout sites are found on jetties, offshore rocks and coastal islands. This species may also be found occasionally on navigation buoys in Puget Sound as well.

Since 70’s, their number has declined, some people believe because of lack of food due to excessive fishing. Also, one must not forget the human factor since they are often the target of the fishermen, especially in Japan and are also affected by the issues regarding climate changes.

However, US government established in 1990 no-buffer zones around rookeries with Steller sea lions. In Canada, they are protected under the Fisheries Act from intentional killing. In addition, many procedures, harvest limitations and measures have been enforced in recent years which, together with the Revised Recovery Plan from 2008, brought to their stable and steady growth in numbers. Their primary natural predators are sharks and killer whales.

Notable experts: Markus Horing, Jo-Ann Mellish, Wynne Kate and Phillip R Mundy

Further reading:
http://www.iucnredlist.org
https://alaskafisheries.noaa.gov
http://www.fisheries.noaa.gov
http://www.marinemammal.org

Diving with Steller Sea Lions