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(Shaw, 1800) - South American sea lion

Distinctive Characteristics

The South American sea lion is stocky in build. In both sexes the muzzle is blunt; although relatively short, it is deep, wide, and slightly upturned at the end. The lower jaw is particularly large, wide, and deep and it juts slightly beyond the upper jaw. The ear pinnae are small and lie close to the side of the head; they are especially inconspicuous in adult males. Adult males are unmistakable, bearing a mane of long, coarse, erectile guard hairs, extending from forehead to shoulders and chin to midchest. The neck, head, and jaws are much more massive than those of females. Their great anterior bulk makes the hind quarters seem too small.

Adult females and subadults of both sexes have coats shaded from yellow to brownish orange. They are not necessarily uniformly coloured, but can be patterned with areas of slightly different hues. Most males darken with age, becoming brownish orange, although the mane and underparts frequently remain lighter. Males sometimes have a darker face, giving them a slightly masked appearance. Adults of both sexes can be pale gold in colour. Pups are born black above and greyish orange below. They undergo their first moult approximately 1 month after birth, becoming dark brown. This colour fades during the rest of the first year to a paler brown to tan colour, with paler areas in the face.

The dental formula is I 3/2, C 1/1, PC 6/5.

Can be confused with

The South American fur seal is the only otariid that regularly shares the range of this sea lion. At least 5 other otariids occur, mostly as vagrants, within the range of the South American sea lion: the Juan Fernandez, Galapagos, Antarctic, and subantarctic fur seals, and the Galapagos sea lion. For each of these, note characteristics of the fur, mane of adult males, flippers, head and muzzle, and ear pinnae.

Size

Males reach 2.8 m in length and weights of up to 350 kg; females reach 2.2 m and 144 kg. At birth, pups are 11 to 15 kg and 78 to 85 cm long.

Geographical Distribution

South American sea lions are widely distributed, occurring more or less continuously from northern Peru on the west side of South America, northward up the east coast to southern Brazil, including the Falkland Islands. This is primarily a coastal species, usually found over the continental shelf and slope. They less frequently occur in deeper waters. South American sea lions venture into fresh waters in rivers and around glaciers.

Biology and Behaviour

The timing of the breeding season in this species varies by location and latitude. The earliest breed in September, the latest in March. In many areas the peak is from mid-December to early February. Most pups are born from early to late January. Generally, rookeries are continuously occupied by at least some animals, and the species has been described as sedentary. Although there is no known migration, many animals, particularlymales, may disperse widely. At sea South American sea lions frequently raft alone or in small to large groups. They have been reported in association with feeding cetaceans and seabirds.

They are opportunistic feeders, taking a wide variety of prey. Their diet includes many species of benthic and pelagic fishes, and invertebrates such as lobster krill, squid, octopus, and jellyfish (and occasionally penguins and young South American fur seals).

Exploitation

Humans have exploited South American sea lions for hides, meat, and fat from prehistoric times to the present. Native peoples, explorers, sealers, and government-sponsored commercial ventures have taken their toll on sea lion populations at various times. Commercial harvesting continues in Chile, while throughout its range the South American sea lion is generally regarded as a nuisance and competitor with local fisheries. Many animals are taken annually in gillnets or are shot or killed with explosive charges set off near them when they approach fishing nets. Sea lion meat is regularly used as bait in crab trap fishing operations in some regions. This species may be in danger, at least in portions of its range, from overfishing of vital food stocks. Historically, more than 300,000 may have inhabited the Falkland Islands alone, whereas surveys from 1965 yielded an estimate of only 30,000.

IUCN Status

Insufficiently known.

South American sea lion (Otaria byronia)