California Sea Lion

The California sea lion is the well-known performing "seal" of zoos, circuses, and oceanaria. In both sexes, the muzzle is dog-like and long, slightly tapering to a moderately blunt end. Adult males are substantially more robust and larger than females. In adult males, the sagittal crest creates a high peaked crown. The crest begins to emerge at sexual maturity and, although highly variable, is most prominent in full-grown males. On most males, especially darker individuals, the crest and a corresponding area on the muzzle and around the eyes lighten with age. Females lack a pronounced crest and have a thinner head that slopes more gently to the end of the muzzle. This makes subadult and juvenile males very difficult to distinguish from females. Colour of California sea lions is highly variable. When dry, the coat of most adult males is dark brown. However, many males do not darken completely, remaining sandy brown on the sides, belly, and rear quarters. Adult females and juveniles are uniformly tan. Pups are born with a thick brownish black lanugo that is generally moulted by the end of the first month. The succeeding light brown juvenile coat is shed 4 to 5 months later, and is replaced by adult coloration. All ages and sexes have contrasting black flippers, naked except for a short stubble of dark fur partially covering the upper surface. The dental formula is variable, but is usually I 3/2, C 1/1, PC 5/5 (in the California race) or PC 6/5 (in the Galapagos race). Can be confused with: California sea lions share their range with 3 other otariids (Steller sea lions, and northern fur seal and Guadalupe fur seal). Galapagos sea lions overlap with Galapagos fur seals and South American sea lions. These sea lions can be separated from the similar, but much larger, Steller sea lion and similar sized South American sea lion, on the basis of head and muzzle shape and size, and relative size of the ear pinnae. Additionally fore- and hindflippers are relatively shorter than in the Steller sea lion. (See the Guadalupe, Galapagos, and northern fur seal accounts for more detail on separating California and Galapagos sea lions from fur seals.)

Male California sea lions reach lengths of 2.4 m, and weights of more than 390 kg. Females only reach 2 m, and weigh an average of 110 kg. Newborn pups are about 80 cm long and 6 to 9 kg. There is very little information on the sizes of Galapagos sea lions (estimated weights are 200 kg for males, and 50 to 100 kg for females).

Breeding takes place from May through July (California sea lions), and from May through January (Galapagos sea lions). Males are highly polygynous and hold territories both on land and in shallow water nearshore.In California sea lions, most adult males and many subadults and juveniles of both sexes take part in a post-breeding migration northward from the rookeries. Galapagos sea lions apparently stay around the Galapagos Archipelago all year. At sea, California sea lions often raft at the surface alone or in groups. Animals in such rafts frequently raise their flippers out of the water. California sea lions often "porpoise" when traveling rapidly at sea, sometimes in large groups. Juveniles and subadults may perform acrobatic and high vertical leaps, and individuals of all ages surf breakers and ride in the wakes of vessels. California sea lions are often seen with a wide variety of dolphin and baleen whale species.California sea lions feed on squid, octopus, and many species of fishes. Because of their taste for commercially important fish species and their boldness, California sea lions are considered a nuisance by many sport and commercial fishermen.

Currently, there is no significant direct catch of California sea lions. Many sea lions, however, are shot by fishermen and certainly many others are taken incidentally during fishing operations. Set gillnets and driftnets, in particular, appear to be taking large numbers each year. The total population of the California sea lion in 1989 was estimated to be 160 000 and increasing, about equally split between Mexico and the United States. The numbers of Galapagos sea lions are unknown. Unfortunately, the Japanese race of this sea lion is now extinct. IUCN: Insufficiently known; extinct (Zalophus californianus japonicus only).