California Sea Lions and Sea Lion Species

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sea lion species, From Animal Spot

Common name (Scientific name), Subspecies, Numbers
Australian sea lion (Neophoca cinerea), endangered, 6,500
New Zealand sea lion (Phocarctos hookeri), Endangered, 3,031
California sea lion (Zalophus californianus), 180,000
Galápagos sea lion (Zalophus wollebaeki), Endangered, 9,200–10,600
Japanese sea lion (Zalophus japonicus), extinct
South American sea lion (Otaria byronia), 222,500
Steller sea lion (Eumetopias jubatus), 81,327: Subspecies: Western Steller sea lion (E. j. jubatus), 40,409; Eastern Steller sea lion (E. j. monteriensis), 40,919

The South American sea lion forms breeding colonies across southern South America from Peru to Uruguay. In Spanish they are know as “Lobos marinos”, or sea wolves.

The Australian Sea lion is a nonmigratory pinniped. It spends it entire life around beaches where it is born and has become tolerant to seal-watching tourists. They were never very numerous. There are thought to be less than 6,000 of them today.

The New Zealand sea lion lives in island groups south of New Zealand. Also known as Hooker’s sea lion, it was nearly wiped in the 19th century but are now protected. Males are almost black. Females and young males are silvery gray.

Websites and Resources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Fishbase; Encyclopedia of Life; Smithsonian Oceans Portal ; Monterey Bay Aquarium ; MarineBio

Steller Sea Lions

From Animal Spot

Steller Sea lions are the largest of the eared seals, with males weighing as over a tonne. The body length of males is 2.6 to 3.9 meters (8.5 to 12.8 feet); females, up to 2.6 meters (8.5 feet). Males generally weigh around 1100 kilograms (1.2 US tons); females, 270 to 350 kilograms (600 to 770 pounds. They live in the North Pacific and breed in Kamchatka, Sakhalin Island and the Pribilof Islands. I the eastern Pacific Ocean they are found as far south as southern California.

Steller sea lions live in coastal waters and offshore islands in the North Pacific. Larger than fur seals, they are named after the German naturalist Georg Steller, who explored the Kamchatka peninsula of eastern Russia in 1940. During the breeding season Stellar sea lion males vigilantly guard their territories. They often do not eat and rely solely on far reserves, At their rookeries, the males behave uneasily and are constantly roaring with a lingering bass roar that is reminiscent of a steamer horn. The roar can be heard for several kilometers away.

Steller sea lions are listed as a near endangered species. They have attracted attention in recent decades due to their significant (and largely unexplained) declines in their numbers over an extensive portion of their northern range—notably in Alaska. Their population declined 80 percent in the 1970s, 80s and 90s to 33,600. They lion are believed to victims of the massive nets used in industrial fishing that have taken the fish the sea lions would eat. The nets are used primarily to harvest pollock, a white fish turned into fish sticks, imitation crab, and fish fillets for fast food restaurants. The disappearance of Arctic ice is blamed. In the last couple of decades their numbers have rebounded somewhat and they are no longer regarded as endangered.

California Sea Lions

California sea lions (Scientific name:Zalophus californianus) are “eared seals” native to the West Coast of North America. They are commonly used as trained performing animals in zoos, circuses and ocean park shows. They are easily trained and intelligent and have also been used by the U.S. military.

20120522-sea lion Zalophus_californianus_male_and_female.jpg
male and female California sea lion
California sea lions They live in coastal waters and on beaches, docks, buoys, and jetties. California sea lions are playful, intelligent, and very vocal (sounding like barking dogs). Adult males weigh up to 300 kilograms (660 pounds) and develop a prominent forehead bulge. They breed across the California coast and in the Galapagos Islands.[Source: NOAA]

The lifespan of California sea lions is 20 to 30 years In captivity, the oldest recorded one lived to be 31 years old. The age of California sea lions can be determined by counting the number of rings on cross sections of its teeth. Their main known predators are great white sharks, bull sharks, orcas (killer whales) and humans.

Feeding: California sea lions feed mainly offshore in coastal areas. They eat a variety of prey — such as squid, anchovies, herring, Pacific whiting, rockfish, hake, salmon, octopuses, mackerel 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. They tend to feed alone or in small groups unless there is a large quantity of food. When food supplies are plentiful, California sea lions hunt in larger groups. Males have been known to gather at the mouths of freshwater rivers where there is a steady supply of fish. California sea lions have been observed cooperatively with cetaceans (whales, dolphins), seabirds and harbor porpoises. Often one species locates a school of fish and signals the presence of food to the other species.[Source: Rebecca Price, Animal Diversity Web (ADW) /=]

California Sea Lion Habitat and Where They Are Found

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.

California sea lion range

California sea lions are found along the shores from California to Mexico including Baja and Tres Marias Islands, in the Galapagos Islands. They used to be found in the southern Sea of Japan. The populations in each area do not interact with other populations and are consequently considered subspecies. California sea lions may seasonally migrate long distances. Males in California often migrate north to British Columbia after the breeding season. [Source: Rebecca Price, Animal Diversity Web (ADW) /=]

The primary breeding range of California sea lions 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. [Source: NOAA]

California sea lions generally live along coastlines but have been found in rivers along the northern Pacific coast. They are often seen congregated on man-made structures such as jetties, piers, offshore buoys and oil platforms. They can be found in many places that have been altered by human intervention.

California Sea Lion Physical Characteristics

Sexual dimorphism (differences between males and females) is pronounced among California sea lions, with males being much larger than females. Males reach a length of 2.3 meters (7.5 feet) and weigh 320 kilograms (700 pounds). Individuala weighing 390 kilograms (859 pounds) and measuring 2.4 meters (7.9 feet) in length have been recorded. Females reach a length of 1.8 meters (6 feet) and weigh 110 kilograms (240 pounds).

California sea lion skeleton

California sea lions are endothermic (use their metabolism to generate heat and regulate body temperature independent of the temperatures around them). Their normal body temperature 37.5º C (99.5ºF) . Because California sea lions cannot sweat or pant they must alter their exterior environment to thermoregulate . For example, if they get too hot on land they need to enter water to cool off. [Source: Rebecca Price, Animal Diversity Web (ADW) /=]

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 measure 75 centimeters (2.5 feet) in length and weigh about seven kilograms (16 pounds). When pups are 4 to 5 months old, they molt their dark brown coats for light brown or silver coats. [Source: NOAA]

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. Adult males have an enlarged saggital crest on their heads and a lighter-colored fur. In addition to the head features males are more robust than females. All California sea lions have black flippers which are coated with short black stubble. The typical dental formula is 3/2, 1/1, and 5/5.

California Sea Lion Behavior and Swimming

California sea lions are motile (move around as opposed to being stationary), migratory (make seasonal movements between regions, such as between breeding and wintering grounds), territorial (defend an area within the home range), social (associates with others of its species; forms social groups), colonial (living together in groups or in close proximity to each other), and have dominance hierarchies (ranking systems or pecking orders among members of a long-term social group, where dominance status affects access to resources or mates). They sense using touch and chemicals usually detected with smell. [Source: Rebecca Price, Animal Diversity Web (ADW) /=]

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. [Source: NOAA]

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. Pups exhibit many different play behaviors including mock fighting. [Source: NOAA]

California sea lions are capable of diving to depths of 274 meters (900) and can reach speeds of 24 to 32 kilometers per hour (15 to 20 miles per hour) while swimming. 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. While rare, it has been recorded that California sea lions drink seawater when not breeding. [Source: NOAA]

Many seals use their sensitive whiskers to locate objects in dark sea water and it seems likely that California sea lions do too. They seem use their whiskers rather than echolocation (emitting sound waves and sensing their reflections to determine the location of objects) like dolphins and whales to find food, orient themselves, and navigate underwater.

California Sea Lion Mating, Reproduction and Offspring

California sea lions seals are viviparous, meaning they give birth to live young that developed in the body of the mother, and engage in seasonal breeding. The breeding season lasts from late June to early August; most pups are born from May through June, with the number of offspring being one. The average gestation period is 11 months. The weaning age ranges from six to 12 months. Females can reach sexual maturity as early as age three. Males do so at four to five years. [Source: Rebecca Price, Animal Diversity Web (ADW) /=]

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 nine to 12 years old. Three to four weeks after giving birth, females are ready to mate again. [Source: NOAA]

According to Animal Diversity Web: During breeding season males claim territories. A male consistently occupies a territory until factors change and cause him to be displaced. Typical occupation time is approximately two weeks; few California sea lions males remain at their site for longer. While guarding their territory, males remain present and do not leave even in pursuit of food. As external factors change, males replace other males on the territory. Replacement occurs throughout the entire breeding season. Males are known to attack if others invade their territory. California sea lions tend to breed on islands or remote beaches. California sea lions exhibit moderate to extreme polygyny and tend to live in colonies of a few males and many females. Female California sea lions exhibit mate choice, by "respond[ing differently to the attempts of various. /=\

California Sea Lion Parenting and Offspring

Parental care is carried out by females. Pups are dark brown at birth and weigh about seven kilograms (16 pounds) and average 75 centimeters (2.2 feet) in length. The weaning age ranges from six to 12 months. California sea lions sometimes adopt and foster a pup that has been abandoned by its mother. [Source: Rebecca Price, Animal Diversity Web (ADW) /=]

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. [Source: NOAA]

According to Animal Diversity Web: The lactation period in California sea lions ranges from six months to a year. There are many possible reasons for the variation in lactation periods including availability of food resources, the mother's age and health, the sex of the pup and the birth of a new pup. California sea lions provide more lengthy maternal care for female offspring then for male offspring, yet during lactation both males and females have equal access and receive equal resources. /=\

California Sea Lions and Humans

California sea lions are widely used for entertainment and educational programs throughout the world because of their agility and trainability. They are commonly featured as performing animals in zoos, circuses and ocean park shows. They are easily trained and intelligent and have also been used by the U.S. Navy for retrieval programs, including search and rescue and retrieval of military hardware. They are also used to patrol areas in search of threats. [Source: Rebecca Price, Animal Diversity Web (ADW) /=]

California sea lions used to be hunted for their hides and for animal food. They are regarded as pests by some fishermen who blame them for seriously reducing stocks of commercially-valuable fish such as salmon. They also may interfere with nets used by fishermen. Occasionally California sea lions pose a problem for fishermen by stealing fish from their nets.

California sea lions are well protected in most areas. Occasionally, they are trapped with a permit for display in zoos, aquariums, and circuses. In Mexico, a few California sea lions are trapped each year, while in the United States they are fully protected under the Marine Mammal Protection Act. /=\

California Sea Lions, Threats and Conservation

California sea lions as whole are not endangered but some populations are. They are designated as a species of least concern on the International Union for Conservation of Nature (IUCN) Red List and have no special status according to the Convention on International Trade in Endangered Species (CITES). According to the IUCN, the following subspecies are recognized: 1) Zalophus californianus ssp. japonicus (extinct); 2) Zalophus californianus ssp. wollebaeki (vulnerable); 3) Zalophus californianus ssp. californianus (no special status). Like all marine mammals, California sea lions are protected under the Marine Mammal Protection Act (MMPA). Their population has been increasing since at least 1975, after protections were put in place under the MMPA. The U.S. stock of California sea lions has grown by 6.2 percent, on average, since 1983.

Threats include entanglement in fishing gear, biotoxins resulting from harmful algal blooms, and human-caused injuries. 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. [Source: NOAA]

Entanglement: 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. [Source: NOAA]

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.

Human-Caused Injuries: 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.

In 1970, a disease called leptospirosis spread throughout the California sea lion population via urine. This disease was the first documented widespread disease in marine mammals. The origin of the leptospirosis was believed to be Mexico due to the warmer water there, which was conducive to bacteria growth. From 1983 to 1984, after the 1982-83 El Nino, California sea lion pup production declined by 60 percent from previous years. Also during this time food resources declined, leading to inhibited growth and increased mortality, and mothers left their pups earlier in search of food, which reduced the lactation period, reducing the amount of nutrients pups received and making them more susceptible to death. [Source: Rebecca Price, Animal Diversity Web (ADW) /=]

Image Sources: Wikimedia Commons, NOAA

Text Sources: Animal Diversity Web (ADW); National Oceanic and Atmospheric Administration (NOAA); Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.

Last Updated June 2023

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