U.S. Department of Commerce


Date of this Version



Published in MARINE MAMMAL SCIENCE, 25(2): 487–502 (April 2009).


Guadalupe fur seals (Arctocephalus townsendi) were decimated by 19th century commercial sealers in the northeastern Pacific and thought to be extinct until 1928 when commercial fishermen caught two adult males at Isla de Guadalupe from a group of up to 60 adults and pups (Wedgeforth 1928, Huey 1930). These two animals were brought to the San Diego Zoo, prompting several zoological expeditions to Isla de Guadalupe in the 1930s and 1940s, but none successfully located Guadalupe fur seals. In 1949, a single male was seen on San Nicolas Island, California (Bartholomew 1950), and in 1954, a small breeding group of animals was found in a cave at Isla de Guadalupe (Hubbs 1956). The population had grown to at least 500 animals in 1967, to about 7,400 animals in 1993, and to 12,176 in 2003, with breeding populations currently confined to Mexico’s Islas de Guadalupe and San Benito (Peterson et al. 1968, Gallo-Reynoso 1994, Gallo-Reynoso et al. 2005, Carretta et al. 2007). Although small numbers of Guadalupe fur seals haul out on the California Channel Islands today, including a female and single pup born on San Miguel Island in 1997, they are vastly outnumbered by California sea lions (Zalophus californianus), northern elephant seals (Mirounga angustirostris), northern fur seals (Callorhinus ursinus), and harbor seals (Phoca vitulina), all of which currently breed on San Miguel Island (Stewart et al. 1993, Melin and DeLong 1999, DeLong and Melin 2002). Archaeological and genetic data suggest, however, that the modern distribution and abundance of Guadalupe fur seals are very different from prehistoric distributions (Walker and Craig 1979, Colten 2002, Etnier 2002a, Walker et al. 2002, Weber et al. 2004).