Four genera of otariids still inhabit the ancestral home of this family, the north Pacific Ocean (northern fur seal, Cal-
lorhinus ursinus; Steller sea lion, Eumetopias jubatus; California sea lion, Zalophus californianus; Guadalupe fur seal, Arcto-cephalus townsendi). All four co-occur only at San Miguel Island, California. Two species (Galápagos fur seal, A. galapagoensis, and sea lion, Z. wollebaeki) live at the equator, and two (South American sea lion, Otaria byronia, and fur seal, A. australis) are found along the Pacific and Atlantic coasts of South America and associated islands. One species (Juan Fernández fur seal, A. philipii) is confined to the Juan Fernández Islands off Chile. One species (Cape fur seal, A. pusillus pusil-lus) occurs around the tip of southern Africa, and a subspecies (Australian fur seal, A. p. doriferus) occurs only in Australia. New Zealand and Australia have one species of sea lion each (Hooker's [Phocarctos hookeri] and Australian sea lion, respectively), and the New Zealand fur seal (A. forsteri) is found in both places. The subantarctic fur seal (A. tropicalis) breeds on a series of islands from the latitude of New Zealand to the Antarctic Convergence. Finally, the Antarctic fur seal (A. gazella) breeds south of the convergence in the Atlantic and Indian Ocean sectors of the Southern Ocean, and extends as far south as the Antarctic Peninsula. The extent to which the distributions of modern otariids reflect the depredations of
The Australian sea lion (Neophoca cinerea) spends much of its time on land. (Photo ©Tony Wu/www.silent-symphony.com. Reproduced by permission.)
nineteenth-century sealing, which nearly exterminated some species, is not known.
The at-sea distributions of otariids are poorly known because the main source of data has been satellite transmitters attached to foraging mothers. The two Galápagos species are believed to forage locally. But species like the subantarctic, Juan Fernández, and Guadalupe fur seals are known to forage over moderately large 580 mi2 (1,500 km2) areas. The northern fur seal makes an annual migratory loop from breeding colonies as far north as the Bering Sea, south over the open ocean to about 35°N latitude, then north to the breeding islands again along the continental shelf break. The Antarctic fur seal may also migrate, but its pathway is less well known because it was never hunted at sea as the northern fur seal was.
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