What you should know about Steller sea lions | Beach Watchers
October 30, 2008 · 1:28 PM
By Dennis Linden
This is the time of year when large male Steller sea lions start showing up in the archipelago.
Their favorite haul-out spot is Whale Rocks, a couple of small, rugged islands off Cattle Point. With a good set of binoculars, these huge animals can be seen easily as they are the largest eared seals in the world, being 10-11 feet in length and weighing in on average at a trim 2,400 pounds. Their fur is light reddish brown and adult males develop thick neck muscles covered by long coarse hair, which look like a mane, hence the name “sea lion.”
There are two stocks of Steller sea lions. The Western stock is generally located along the extreme northern coast and islands of Alaska; the Eastern stock ranges from Southern Alaska to the Northern California coast. The species has fore-flippers with long digits for propulsion in water and hind-flippers that rotate forward under their hips for “walking” on land.
Our visitors here on Whale Rocks are primarily males who have come into the Salish Sea to rest and fatten up. The Steller is an equal-opportunity forager who will eat whatever is available. Their diet includes pollock, cod, sand lance, eel, salmon, mackerel, rockfish, flatfish, herring, lamprey, octopus, squid, even northern fur seal pups, small harbor seals, ringed seals and sea otters.
This area serves as their winter training camp in preparation for the annual spring territorial battles at the 13 rookeries located in remote locations along the Northern California, Oregon and British Columbia coasts. They fight to occupy and lord over small plots of ground that entitle each bull to mate with all females in their hard-won kingdoms. Both males and females mature at about the same age, 3-6 years old; however, to hold a territory a male is usually 8-10 years of age.
The boys on Whale Rocks must fatten up because being king of a harem of lady Stellers requires defense and mating 24/7 for two months on land without any opportunity to eat. There are no breeding grounds in Washington state, so our islands are neutral territory for yet another group of annual vacationers.
Interestingly, females are full-time residents at the rookeries, whether they are caring for a pup or not. The males are much more transient foragers traveling long distances once their mating duties have been completed. Even so, they will normally return to either the same rookery next season or one that is in the same general vicinity of their own birth looking for that prized beachfront property and the wives who come with it. Females live for about 30 years; males have a life span of only 20 years.
Tragically, as with many marine species these days, the Western stock is listed as endangered under the Endangered Species Act and our Eastern stock’s official status is threatened. Steady decline in the populations of these amazingly powerful creatures, who have flourished in these waters for centuries, has been attributed to over fishing and the decimation of habitats that support their food supply.
This just happens to parallel with an increase in the population and activities of a two-legged environmental predator who has moved into the region over the last 100 years.
— Dennis Linden is a WSU Beach Watcher on San Juan Island. WSU Beach Watchers serve these islands through education, research and stewardship.