Overview

Key Features:

Brown, with ears, and large foreflippers. Large, older males can have a white, tufted crown on top of their head.

Similar Species:

Fur seal (Callorhinus ursinus)
Steller sea lion (Eumetopias jubatus)

Primary Common Name:

California sea lion

General Grouping:

Whales, seals and sea lions, otters

Geographic Range:

British Columbia to Mexico

Resident along entire coast; breeds mainly on the Channel Islands off southern California. Zalophus californianus can also be found breeding at islands along the northern Pacific coast of Baja Californa, including the offshore Guadalupe Island, and on islands along the east coast of Baja California in the middle and southern Gulf of California.
Maximum Depth: 536 meters or 1784.88 feet

Notes:

Can regularly dive to 75 m for four minutes.

Habitats:

bay (rocky shore), bay (sandy shore), Continental shelf, estuary, exposed rocky shore, kelp forest, pelagic zone, protected rocky shore, protected sandy beaches

Notes:

Zalophus californianus will occupy shallow ocean waters, sea caves, rocks, and beaches. They will also congregate at marinas, wharves and buoys. The maximum recorded diving depth for the species is 536 m and the maximum duration is 12 minutes. Zalophus californianus may spend several days at a time at sea, and as much as one to two weeks in some seasons. Whiles at sea, they dive almost continuously, resting only briefly at the surface.

Abundance:

Relative Abundance:

Abundant at certain times of the year, and variable from year to year.

Species Description:

General:

Zalophus californianus belongs to one of three closely related pinniped families in the order Carnivora. Zalophus californianus is in the Otariidae, or eared seal, family. There are three subspecies of Zalophus californianus, the California Sea Lion, Zalophus californianus californianus, the Galapagos Sea Lion, Zalophus californianus wollebaeki, and the Japanese Sea Lion, Zalophus californianus japonicus (presumed extinct). These three subspecies have been elevated to separate species by some: California Sea Lion, Zalophus californianus, the Galapagos Sea Lion, Zalophus wollebaeki, and the Japanese Sea Lion, Zalophus japonicus.

Zalophus californianus has a streamlined body that contains a layer of blubber under the skin to provide warmth and buoyancy. Large eyes help them adjust to low light levels in underwater environments, while whiskers enhance their sense of touch. Their nostrils automatically close once they hit the water. Long front flippers rotate outward for better movement on land, and propel them forward in water, where they are most at home. Males grow a large crest of bone on the top of their heads as they reach sexual maturity, and it is this that gives the animal its generic name, Zalophus californianus means Californian Big-head.

Zalophus californianus is perhaps the most familiar pinniped in the world. They are highly gregarious, intelligent and easily trained. These are the sea lions commonly seen in zoos, circuses, and ocean parks. They are also trained by researchers interested in studying interspecies cooperation in the marine environment as well as being used by the U.S. Navy Marine Mammal Program for equipment recovery and in military applications as sentries.

They are quite active, both behaviorally and vocally in captivity as well as in the wild. Zalophus californianus can be easily recognized by its noisy, honking barks. Along the Pacific coast of North America, they are well known for frequently visiting boating marinas, sometimes hauling out by the dozens on yachts, bait barges, and buoys. Because they have been known to actually damage and even sink boats, they are often seen as a unwanted pest at harbors. Zalophus californianus are also impacting salmon runs at river mouths and wharfs where they aggregate to feed on the spawning salmon.

Distinctive Features:

Adult females and juveniles are slender-bodied, while adult males are robust at the shoulders, chest, and neck, and only slender at the hind end. The snout is long, straight and narrow. The fore flippers are broad and have hair on the upper surface that extends past the wrist and tiny claws. The short hind flippers have short fleshy tips at the end of the digits and short narrow claws. While adult males do not have the well-developed mane typical of other sea lions, they do have a pronounced forehead that is exaggerated by the tuft of light brown to blond tuft of hair that crowns the sagittal crest. There are nine pairs of teeth in the upper jaw and eight pairs in the lower jaw. Adult males are mostly dark brown to black with areas of light tan on the face. Adult females are usually blond or tan, except right after the annual molt when they are light gray to silver. Pups are born dark brown to black but fade to light brown within a few weeks. Pups molt at about four or five months old to a light gray coat that darkens to chocolate brown, then fades to light tan or yellowish over several months. Males generally do not fade to lighter tan after molting after they reach puberty. A small number of males, however, remain light yellow to blond throughout their lives.

Size:

At birth <em>Zalophus californianus</em> is 78 cm in length and weighs 6-9 kg. Adult males grow to a maximum length of 2.3 m and 25 cm and females to 2 m and 18 cm. Adult males and females can reach a weight of 390 kg and 110 kg respectively. <em>Zalophus californianus</em> is smaller than the Northern Sea Lion, <em>Eumetopias jubatus</em>.

Natural History:

General:

Zalophus californianus forms large aggregations when ashore, particularly on the Channel Islands, where thousands may haul out in dense groups. They may also travel and cavort in groups of a dozen or more when at sea, near haulouts and breeding beaches, and perhaps when en route to offshore foraging areas. Zalophus californianus likely lives for 20-30 years for females, slightly less for males. The population is estimated at about 175,000 individuals. This is a fourfold increase since the 1970s when the United States and Mexico limited killing and harassment of the species.

Predator(s):

Zalophus californianus was hunted along the west coast of North American and at the Channel Islands for at least several thousand years before the arrival of Europeans in the 16th century. Early whalers, sealers, and sea otter hunters probably killed them for food in the 1800s and 1900s as well. There was a small scale commercial harvest of Zalophus californianus in Baja California and southern California from the 1920s through the early 1940s. In the early 1900s bounties were paid for Zalophus californianus in Washington, Oregon and California because of the perceived competition with commercial fisheries.

Prey:

Zalophus californianus exhibits a diverse diet, with northern anchovy, market squid, sardines, pacific and jack mackerel, and rockfish among their favored prey.

Feeding Behavior:

Carnivore

Notes:

Zalophus californianus feeds mostly in cool, upwelling waters near the mainland coast, along the continental shelf edge, and around seamounts, and may also sometimes forage on the sea bottom. Zalophus californianus is also notorious for approaching commercial and sport fishing boats and seizing fish from lines and nets. In northern California, Oregon, and Washington male Zalophus californianus position themselves at the mouths of streams and rivers to intercept lampreys, salmon, and eels that become densely concentrated there during annual migrations.

Seasonal Behavior

September - December

Migration:

After the breeding season, large numbers of Zalophus californianus, particularly males, migrate north in the Gulf of California and along the Pacifica coast of North America as far as British Columbia. Adult females and juveniles molt from early autumn through winter, and adult males appear to molt in January and February after they have migrated north. There are an increased number of sub-adult and adult males ashore at the Channel Islands in winter, likely hauled out to molt before returning to breeding colonies in Mexico.

May - June

Reproduction:

Zalophus californianus breeds during this time. They are polygamous breeders and form harems. Adult males establish breeding territories along the water's edge or near tide pools, near shore ledges, reefs, or on sandy beaches where females may congregate. Males compete with ritualized physical displays, including aggressive posturing, threat vocalizations, and occasional physical combat. Females have a 12 month gestation period.

June - August

Reproduction:

One Zalophus californianus pup is usually born during this time, and the mother may give birth in land or water. Most births occur in late June. Females remain ashore with their pups for about seven to 10 days, and then begin foraging at sea for one to three days at a time, spending about a day ashore nursing their pups. Pups may accompany their mothers on some foraging trips. Those that remain behind congregate in large groups to socialize and play; their mothers quickly find and reunite with them, recognizing them by vocalizations and smell. Pups are abruptly weaned and abandoned at about six months old, although some may continue to nurse for up to a year, and rarely longer. Females become estrous and are ready to mate about three weeks after giving birth, by which time they are already foraging at sea.

References

• Alden, P., F. Heath, R. Keen, A. Leventer, and W. Zomlefer. 2002. National Audubon Society Field Guide to California. A.A. Knopf, New York, NY.
• Reeves, R.R., B.S. Stewart, P.J. Clapham, and J.A. Powell. 2002. National Audubon Society Guide to Marine Mammals of the World. A.A. Knopf, New York, NY. 527 p.

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