California Sea Lion
About the Species
California sea lions are “eared seals” native to the West Coast of North America. They live in coastal waters and on beaches, docks, buoys, and jetties. They are easily trained and intelligent and are commonly seen in zoos and aquariums. California sea lions are playful, intelligent, and very vocal (sounding like barking dogs).
Like all marine mammals, they are protected under the Marine Mammal Protection Act. Their population has been increasing since at least 1975, after protections were put in place under the MMPA.
NOAA Fisheries helps conserve the California sea lion through collaborative management, integrated science, partnerships, and outreach. Our scientists use innovative techniques to study, protect, and rescue California sea lions in distress—for example, stranded or caught in nets. Our work helps reduce harm from human activities (such as fishing and pollution) through management based on sound science, public input, and public outreach.
NOAA Fisheries estimates population size for the U.S. stock of California sea lions in our stock assessment report. The U.S. stock of California sea lions has grown by 6.2 percent, on average, since 1983.
- Throughout Its Range
Adult females and juveniles are slender-bodied and are blonde to tan in color. Adult males are generally larger than females and are mostly dark brown to black in color. Pups are dark brown at birth and weigh about 16 pounds. When pups are 4 to 5 months old, they molt their dark brown coats for light brown or silver coats.
California sea lions have broad front flippers and long, narrow snouts. Subadult and adult males have pronounced forehead crests crowned with tufts of blonde or lighter hair. California sea lions have visible ear flaps, and three to five claws on their hind flippers.
Behavior and Diet
California sea lions feed mainly offshore in coastal areas. They eat a variety of prey—such as squid, anchovies, mackerel, rockfish, and sardines—found in upwelling areas. They also may take fish from commercial fishing gear, sport fishing lines, and fish passage facilities at dams and rivers.
California sea lions are very social on land and in the water, but during the breeding season the males aggressively defend their territories and females fight other females to protect their pups. While on the breeding islands, California sea lions are very skittish of humans and will run into the water if they see or smell people.
California sea lion males bark like dogs to communicate with other males and females. Females and pups communicate using vocalizations that are unique to the female and pup. Each pup and female has a unique scent that also identifies them. A female can locate her pup among hundreds of others by her pup’s vocalization. When she finds her pup, she smells it as a final check.
One common behavior—called “rafting”—can make a sea lion look like it’s caught in a net. A rafting sea lion holds its flippers above the water for a long time, motionless, to rest and regulate its body temperature. If you cannot see a buoy or net gear, the seal is most likely rafting.
Where They Live
California sea lions live in the shallow waters of the eastern North Pacific Ocean. They prefer sandy beaches or rocky coves for breeding and haul-out sites. Along the West Coast, they also haul out on marina docks as well as jetties and buoys. California sea lions range from southeast Alaska to the Pacific coast of central Mexico. Their primary breeding range is from the Channel Islands in southern California to central Mexico. NOAA Fisheries divides the California sea lion population into three stocks (United States, western Baja California, and Gulf of California) based on the location of major rookeries and the international border. The U.S. stock waters ranges from the U.S./Mexico border to Canada. In normal years, male California sea lions migrate during the winter to feeding areas off California, Oregon, Washington, British Columbia, Canada, and southeast Alaska but females and pups stay near the breeding colonies until the pups are weaned. In warm water (El Niño) years, some females are found as far north as Washington and Oregon, presumably following prey.
Lifespan & Reproduction
Males are "polygamous," establishing breeding territories that may include up to 14 females. They defend their territories with aggressive physical displays and vocalization. Sea lions reach sexual maturity at 4 to 5 years old, but do not become socially mature until much older—they begin holding territories at around 9 to 12 years old. Breeding season lasts from late June to early August; most pups are born from May through June. Three to four weeks after giving birth, females are ready to mate again.
California sea lions separate their nursing and feeding activities. A mother sea lion nurses her pup for 1 to 2 days, then leaves the pup ashore while she travels to feeding areas at sea. She spends 2 to 5 days feeding, then returns to nurse. During the mother's absence, the pup doesn’t eat. Females continue a pattern of going to sea for several days and nursing ashore for several days until they wean their pups. This takes almost a year. If you see a pup on the shore, please leave it be. If it looks to be in distress, call your local marine mammal stranding network member.
One of the main threats to California sea lions is getting caught in fishing gear. They can become entangled in many different gear types, including traps, pots, or gillnets. Once entangled, they may drag and swim with attached gear for long distances, ultimately resulting in fatigue, compromised feeding ability, or severe injury, which may lead to reduced reproductive success and death.
Biotoxins from Harmful Algal Blooms
Under the right conditions, algae can grow out of control. Some algae “blooms” produce toxins that can kill fish, mammals, and birds, and may sicken or even kill humans in extreme cases. California sea lions are top predators, which means these toxins can build up in their bodies, possibly leading to seizures or death from domoic acid poisoning.
California sea lions are easy to view in the wild, but this puts them at higher risk of human-related injuries and death. Feeding or trying to feed them is harmful and illegal, because it changes their natural behaviors and makes them less wary of people and vessels. They learn to associate humans with an easy meal and change their natural hunting practices—for example, they take bait catch directly off fishing gear. Sometimes they fall victim to retaliation (such as shooting) by frustrated boaters and fishermen.
They may also be disturbed or harassed by the presence of humans and watercraft. Harassment happens when any act of pursuit, torment, or annoyance might injure them or disrupt their behaviors—and it’s illegal. Remember to share the shore with California sea lions, for their safety and yours.
California sea lions are protected throughout their range under the Marine Mammal Protection Act. NOAA Fisheries is working to protect them in many ways, with the goal that populations stay stable and do not fall to depleted or threatened levels.
Minimizing Harassment and Illegal Feeding
As humans interact more with seals and sea lions, they risk disturbing or injuring these animals. Learn more about how to safely and responsibly view seals and sea lions.
Reducing Interactions with Fishing Gear
California sea lions can get entangled in fishing gear, causing injury and possibly death. NOAA Fisheries is working to better understand and characterize the frequency, geographic extent, and magnitude of these interactions. We are also working with researchers to find and study ways to safely and effectively make these interactions less likely.
Overseeing Marine Mammal Health and Stranding Response
We work with volunteer networks in all coastal states to respond to marine mammal strandings. When stranded animals are found alive, NOAA Fisheries and our partners assess the animal’s health. When stranded animals are found dead, our scientists work to understand and investigate the cause of death. Although the cause often remains unknown, scientists can sometimes identify strandings due to disease, harmful algal blooms, vessel strikes, fishing gear entanglements, pollution exposure, and underwater noise. Some strandings can serve as indicators of ocean health, giving insight into larger environmental issues that may also have implications for human health and welfare.
This species is protected under the Marine Mammal Protection Act of 1972, as amended.
NOAA Fisheries researches the biology, behavior, and ecology of the California sea lion. We use the results to inform management decisions and recovery efforts for this depleted species.
Determining the number of California sea lions in each population—and whether a stock is growing or shrinking over time—helps resource managers assess the success of conservation measures. Our scientists collect information and present these data in annual stock assessment reports.
Unusual Mortality Events
To understand the health of California sea lion populations, scientists study unusual mortality events. Marine mammal UMEs are important because they can serve as indicators of ocean health, giving insight into larger environmental issues that may also have implications for human health and welfare. Since 2013, more pups and yearlings have been stranded than usual in Southern California. Many are emaciated, dehydrated, and very underweight for their age. This event has been declared a UME.
NOAA scientists conduct wide-ranging research on the biology, life history, and health of California sea lions including:
- Diet/foraging ecology.
- Distribution and migration.
- Threats such as disease, contaminants, and entanglement.
Research & Data
Domoic Acid Toxicity in California Sea Lions (Zalophus californianus) Stranded Along the Central California Coast, May-October 1998
NOAA Technical Memorandum NMFS-OPR- 17
Investigations of Peritoneal and Intestinal Infections of Adult Hookworms in Northern Fur Seal and California Sea Lion Pups on San Miguel Island, California
Parasitol. Res. 109:581-589.