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 California Sea Lion

Image Credit: NOAA


 California Sea Lion
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 National Marine Sanctuaries Where California Sea Lions Can Be Found:
  Olympic Coast
Cordell Bank
Gulf of the Farallones
Monterey Bay
Channel Islands

 Related Environmental Issues:
  Point Source - Oil Spills
Non-Point Source - Runoff
El NiƱo
Overfishing
Climate Change

 Activities Related to California Sea Lions:
 

 Other Resources Related to California Sea Lions:
 



Scientific Name: Zalophus californianus

Category: Pinnipeds

California sea lions live off the west coast of the United States, Canada, Mexico and the Galapagos Islands in the Pacific Ocean. The sea lions that live on the Galapagos Islands are considered a subspecies and rarely leave that island. The name "sea lion" comes from the fact that they not only bark like a dog, but they roar like a lion. California sea lions are world famous because they come up into the San Francisco Marina and hang out in giant pile on Pier 39 where tourists come to watch them. You often see them performing in circuses, aquariums, and marine parks. California sea lions can be trained to throw and catch beach balls on their nose, play a set of musical horns, run up and down ladders and clap their front flippers. These shows demonstrate how intelligent the sea lions are. The U.S. Navy has recognized their intelligence and uses them in a variety of ways. Sea lions are very vocal, playful, and sometimes sound like a dog barking. They are good clowns and even appear to have a sense of humor.

Many people confuse sea lions and seals. So, how do you differentiate between the two? 1) Sea lions have external ear flaps, and seals have ear holes, but no flaps; 2) The front flippers on a sea lion are larger than a seal, are hairless (furless) and have short nails. Their flipper is similar to the bone structure of your hand, but the fingers are webbed together with skin. The seals have short, fur-covered front flippers with long claws; 3) The back flippers on sea lions rotate underneath their body, enabling them to walk on all four flippers when on land. When swimming, they propel themselves along with their front flippers and steer with their back flippers. The seals back flippers are much smaller, extend straight back from the body and do not rotate. On land, they move around awkwardly on their tummies; and 4) The whiskers on a sea lion are smooth, the whiskers on a seal are beaded or crimped. Seals are also naturally shier than sea lions, so if you see what looks like a seal at a marine park entertaining tourists, it is a sea lion not a seal.

The males called bulls are chocolate brown in color, weigh 390kg (about 860 pounds) and can reach 2.4m (about 8 feet) in length. Females are a lot smaller; on average adults weigh 110kg (240 pounds) and rarely exceed 2m (about 6.5 feet) in length. In profile, their faces look like dogs because their muzzles are pointed and they have whiskers. Males develop a crest of bone on top of their heads when they are about five years old. Females called cows have golden brown to tan fur, but all California sea lions have brown skin and look black when wet. Sea lions can swim 10.8km per hour (about 25 miles per hour). Sea lions cannot stay underwater forever because they are mammals and must breathe air. When they dive, their nostrils close automatically, allowing them to remain submerged on one giant breath for as long as 40 minutes. They have excellent sight and hearing. The sea lion is well-suited to an aquatic habitat because it has flippers for mobility, a layer of blubber for body insulation, and a hydro-dynamically designed body (good for swimming). As the male sea lions age, their head fur turns grey. The life span of a sea lion is about 25 years. Sea lions sometimes bunch up in the ocean and float together, making a giant raft. They have also been seen surfing the waves off Malibu. (However, reported sightings of their use of sunglasses and surfboards are thought to be exaggerated.)

While California sea lions eat a variety of seafood, they predominately enjoy feeding on salmon, hake, pacific whiting, octopus, anchovies (the pizza variety), and squid. They can eat alone, but the sea lions are highly social and are often seen eating in groups. Where there are large schools of fish, they share food with dolphins, sharks and sea birds. On cool days, the sea lions will move inland and when they are not breeding, they are comfortable in human environments. They gather in marinas, along wharves and sometimes are seen sitting on navigational buoys. These human areas are generally avoided by the sea lions natural enemies, white sharks and orca whales. The sea lions that live off the coast of Washington State will wait at the mouths of rivers for the salmon to run. They also have been found hanging out below fish ladders (low steps built into waterways to help fish migrate upstream) at the Bonneville Dam and at various sites along the Columbia River, Willamette River and Puget Sound.

The sea lions breed on sandy beaches along the California coast and the Channel Islands west of Los Angeles between June and August. Females are pregnant for about a year and give birth to a single pup either on the beach or in the water. Pups weigh 6-9kg at birth (13-20 pounds), are 75cm (30 inches) in length, and their eyes are open. They have dark fur which lightens when they are several months old. At birth they can communicate vocally with their mothers. They generally nurse on their mothers high fat, lactose-free milk for six months to a year. Mothers start teaching the pups to swim and hunt at about two months of age. Just after the mothers give birth, the males arrive to begin the next breeding cycle. The males fast during the breeding season and they squabble over territory by head shaking, barking, lunging, shoving, biting, and engaging in staring contests. Generally, females far outnumber the males in the rookery and males often end up with as many as sixteen mates.

California sea lions are protected by the Marine Mammal Protection Act of 1972. Before then, they were hunted commercially for their skin and oil. The sea lion population is now increasing and causing pressure on human environments. Fishermen on Pier 39 in San Francisco sell raw fish to tourists to feed them. Wouldn't you come back to a place where you could get a free lunch! They do cause problems though, damaging piers, docks and jetties, fishing boats, and sometimes even injuring surfers in the water. They are even so bold as to steal fish out of the fishermans boats. Sea lions gather at the salmon runs and steal fish from commercial fishermen causing economic and environmental problems. To deal with these problems, legislation has been introduced to control the sea lion population by selective hunting. Scientists tried to relocate the sea lions to other geographic places, but the sea lions outsmarted them by swimming back. Again, why not go where there is a free lunch?

California sea lions get diseases like pneumonia and other bacterial infections. Sick animals are often treated at places like the Marine Mammal Center, north of San Francisco. As they can sometimes be irritating to humans, some people shoot them illegally. Others are caught in fishermans drift nets or human plastic debris. The sea lions are also adversely affected by El Nino weather patterns because these short-term climate changes cause a shortage in their food supply and they die from starvation. They are also sensitive to toxic algae blooms.

One of the most important stories about the California sea lion is that the U.S. Navy has trained them to be a very important part of their operations. The seals can detect underwater mines and can dive as far as 1,000 feet down where human divers cannot go. They also swim silently and cannot be detected on enemy radar. In the Gulf War, sea lions were used in very unusual ways. When enemy frogmen are swimming close to US ships, the sea lions are deployed with a clamp attached to a rope which they silently attach to the enemy divers leg. The diver is then pulled up on the ship. This happens so fast that the divers do not know what hit them. Sea lions are also used to recover equipment from the water.




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Space Administration

(NASA Award NCC5433)
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Atmospheric Administration

(NOAA Award NA06SEC4690006)

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