In the water, the Steller sea lion pulls itself through the water using its front flippers. Other marine animals such as seals, swim with their hind flippers using a body action that is more fishlike. Genetically, there are three distinct populations called the Russian population, Western population and Eastern population.
These sites can be rock shelves, ledges, boulders, and gravel or sand beaches. Adult Steller sea lions eat a wide variety of fishes, including Pacific herring, capelin, sand lance, Atka mackerel, walleye pollock, salmon, Pacific cod, rockfishes, salmon, flatfishes, sculpins, squid, octopus and occasionally seal pups. Most fish are swallowed whole. Large prey are torn apart and consumed at the surface. Sea lions sometimes feed in groups which may help to control the movement of large schools of fish and make them easier to catch.
Diet appears to vary between regions and has also changed through time. The causes and consequences of these changes in diets are still under debate. Young sea lions require twice this amount. Steller sea lions mate and give birth on land. On average, females give birth for the first time when they are 5 years old. A few mothers are as young as 3 years old. Births occur mid-May to mid-July and peak in June. In May, dominant males 9 years and older establish their breeding territories on rookeries, and maintain them for approximately 40 days without eating.
During this time, the males establish a harem and mate with females on their territories. On average, males successfully defend territories for only 2 breeding seasons. Mating occurs about 1 week following the birth of the pups. Pups are able to crawl and swim soon after birth. Pups will approach other females, but are often bitten or thrown by females who have their own pups. The extent of this decline led to the Steller sea lion species being listed as threatened range-wide in April The Western population was listed as endangered in , and there are currently about 46, individuals in this group.
Recent population surveys suggest that for the past 25 to 30 years, the Eastern population has been growing steadily at about 3 percent per year. At certain sites, the number of individuals has more than doubled from to The current minimum population estimate for the Eastern population is approximately 52, individuals. In October , officials removed the Eastern group of Steller sea lions from the endangered species list.
As this group had recovered, it no longer met the definition of an endangered or threatened species. Unlike the Eastern population, the Western group has not met the recovery and de-listing criteria, and remains listed as endangered. Pups typically are born from mid-May to mid-July, weighing 35 to 50 pounds. Mothers stay with their pups for one to two weeks before going off to hunt at sea. Steller sea lions breed, give birth and nurse pups on remote islands called 'rookeries'.
Females are pregnant for a year, after which, they have a single pup. Pups generally nurse for a year, but in some cases, they may nurse up to three years.
At birth, pups weigh between 16 to 23 kilograms pounds and are about 1 meter 3. Both male and female Steller sea lions are ready to breed between the ages of 3 to 6 years; however, due to competition with other males, most males will not breed successfully until they are 8 to 10 years old. Dominant males, females, and new pups live on rookeries during the summer when breeding occurs. Older pups do not stay on rookeries as long because they cannot breed.
After the breeding season ends in August, females and their young move to non-breeding areas, known as 'haul outs'. Steller sea lions are very social and continue living with each other after the breeding season has ended. Female Steller sea lions provide care for their young for as long as three years.
They nurse their young for up to a year, but some will let their young nurse longer. Male Steller sea lions do not provide much parental care for their young; however, males will guard all the females that they impregnated.
After female Steller sea lions give birth, they forage around the rookery and onshore, mostly at night, and may be gone for as long as a day.
After finding a food source, they return and nurse their pup. Male Steller sea lions can live up to 20 years; whereas, females can live up to 30 years. Their lifespan in captivity has not been reported. The main cause of death for Steller sea lions is old age. They are sometimes killed by fisherman because they interfere with fishing nets and fish hatcheries.
Gelatt and Lowry, Steller sea lions are generally social within their populations and can be found in large groups in rookeries or on beaches. Male Steller sea lions do not provide much parental care for their young; however, males will guard all the females that they impregnated. After female Steller sea lions give birth, they forage around the rookery and onshore, mostly at night, and may be gone for as long as a day.
After finding a food source, they return and nurse their pup. Male Steller sea lions can live up to 20 years; whereas, females can live up to 30 years. Their lifespan in captivity has not been reported. The main cause of death for Steller sea lions is old age.
They are sometimes killed by fisherman because they interfere with fishing nets and fish hatcheries. Gelatt and Lowry, Steller sea lions are generally social within their populations and can be found in large groups in rookeries or on beaches. Steller sea lions are usually found in groups ranging from one to twelve, but have been seen with as many as a hundred individuals on a beach. Steller sea lions are typically found along California and further north on the west coast of North America.
Young Steller sea lions usually travel farther than adults, because they are unable to mate they will go farther for food. Steller sea lions communicate with other individuals though low frequency vocalizations that sound like a roar, as opposed to their relative, the California sea lion , whose vocalizations sound more like a bark.
Steller sea lions forage for food along the shoreline and near pelagic waters and are considered opportunistic hunters. Their main food sources include walleye pollock , Atka mackerel , Pacific salmon , and Pacific cod. In the winter, walleye pollock and Pacific cod are their main food source. Atka mackerel is their most common food source all year long.
Steller sea lions will also eat octopus , squid , bivalves , and gastropods. Steller sea lions have also been known to kill other animals, such as harbor seals and ringed seals , along with younger northern fur seals.
Salmon sharks , killer whales , and Pacific sleeper sharks are some of their known predators. The recovery of Steller sea lions is related more strongly to predator abundance than resource abundance.
Great white sharks have been known to kill and consume Steller sea lions if their territories happen to cross. Humans may also prey on Steller sea lions. This species preys on a variety of fish , bivalves , gastropods , and cephalopods. Historically, Steller sea lions were hunted for their meat, fur, and oil; this played a part in the decrease of their population.
Incidental population destruction has also occurred due to fishing nets, ship strikes, pollutants and diseases.
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