(c) Can Stock Photo
The majestic Stellar sea lion makes its home in the northern Pacific Ocean. Considered non-migratory, Stellar sea lions rarely range far in search of food, hunting in open areas after the mating season and moving to sheltered areas during the winter. Stellar sea lions are mammals and the largest of the Otariidaes meaning “eared” seals. Unlike their smaller cousins, sea lions differ from seals in that they have both an external ear, and flippers that rotate forward, allowing them to walk like land mammals. In addition, Stellar sea lions are classified as Pinnipeds, the word literally meaning feather or fin-footed. Males are dark brown in color with large necks and shoulders covered in long coarse hair. Females are lighter in color with a yellowish cream color on their backs. Female sea lions grow quickly for the first four years, with growth substantially slowing after they reach their adult weight by the age of six. Males continue growing rapidly until their eleventh year, reaching their adult weight by the age of 12. Both genders can live to an age of 20 to 30 years. A typical female sea lion weighs approximately 580 pounds and measures just over eight feet in length. By comparison, a full-grown male sea lion weighs about 1,200 pounds and reaches a length of just over ten feet.
Sea lions subsist on a diet of both schooling and bottom feeding fish augmented by the occasional octopus or squid. In addition, Stellar sea lions occasionally kill smaller seals and their pups, the only type of sea lion to do so. These animals are uniquely suited to the waters of the northern Pacific Ocean. Stellar sea lions can swim at a speed of between 17 to 25 miles an hour, dive to a depth of 60 feet, and stay submerged for up to 40 minutes with the help of nostrils that automatically seal when they dive. Sea lions swim using their front flippers in a breaststroke type motion while the hind flippers act as a sort of rudder. Their whiskers are sensitive enabling them to detect and catch nearby fish in dark surroundings.
Sometime around mid-May to mid-July, the bull sea lions come ashore and occupy traditional rookeries. Two weeks later, the cows and juvenile sea lions arrive and the bulls begin gathering their harems. Each male lays claim to a territory and any female who enters this defined space becomes one of his “wives.” The sea lion bull then fights off other males and tries to prevent his cows from leaving. During this time a dominant bull will not eat, devoting all his time and energy to the protection of his territory. At the age of three, most sea lion cows are ready to breed, some cows waiting until the age of six. Once a cow mates, the fertilized egg floats free, not attaching to the uterine wall until October. The resulting pup (or rarely pups) is born during the next mating season. The cow goes back into estrus soon after giving birth thus restarting the breeding cycle. The male sea lion is also ready to mate at the age of three but his chances of doing so are slim. The sea lion bull must wait until he reaches his full adult size and is able to fight for the right to gather his own harem.
Stellar sea lion pups are born with a dark brown coat of hair (not fur) with clear tips, giving them a frosted appearance. At birth, a sea lion pup weighs between 40 and 50 pounds and measures about 4 feet long. Born with their eyes open, sea lion pups are ready for their first swimming and fishing lesson within just a few weeks but will continue to nurse for one to three years. Life for a sea lion pup is hazardous. Not only do they have to learn to avoid killer whales, survive their first trip into the water without drowning, and learn to survive storms, there is a danger of other sea lions trampling them to death within the harem.
Aside from man, Stellar sea lions have only one natural enemy, the orca, or killer whale. Despite this, Stellar sea lion populations have steadily declined over the last 20 years. Today they are included on the U.S. Endangered Species list and protected by the Marine Mammal Protection Act. A combination of factors contributes to their decline, overfishing of their natural food sources, over predation from orcas, climate changes causing shifts in food sources, contaminants in their natural habitats, and shooting by fishermen protecting their nets. The good news is, due in part to their protected status, some Stellar sea lion populations have recently shown an increase in numbers. This gives us hope that, with vigilance, these magnificent animals will be around for many generations to come.
