Arctocephalus australis
South American fur seal

Neotropical ocean coasts; ranges from southern Peru (Paracas Peninsula) south to Cape Horn on the Pacific side, and northward to southern Brazil on the Atlantic side. Also found in the Falkland Islands, Staten Island, and Escondida Island. There are two subspecies, based on size and range. Arctocephalus australis gracilis, the more widespread of the two, occurs throughout the entire range along the mainland. The smaller subspecies, Arctocephalus australis australis, inhabits the Falkland Islands. Recently, a population on South Georgia Island was determined to be A. australis australis (Reeves, et al. 1992, Daneri, et al. 1997, Nowak 1999).

Arctocephalus australis apparently prefer rocky shores and islands, especially those with lots of vertical slope. This provides shady areas for them to escape the heat of the sun. During a given day there may be movement from drier rocks to areas close to the sea or in tide pools. They have been found in sea caves in Peru, where some climb up to 15 meters to find a spot to rest. Not much is known about their movements at sea, but a recent study with satellite telemetry has discovered that females will travel 15 to 200 km when foraging at sea. (Nowak 1999, Falklands Conservation 2000)

Adult males reach an average length of 1.9 meters and mass of 150 – 200 kg. Their fur is blackish gray, with a mane of long guard hairs on the shoulder and neck area. The build of the male is proportionally broader in the shoulders than the female. Adult females average about 1.4 meters in length and a mass of 30 – 60 kg. Female and subadult fur is grayish black on the back and lighter on the ventral side. Newborn pups are all black. In general, these seals have a stocky build with a flat-topped, pointed muzzle and creamy white vibrissae. Ear pinnae are prominent. Dental formula 3/2, 1/1, 6/5. (Reeves, et al. 1992, Jefferson, et al. 1994, Nowak 1999)

South American fur seals have an estimated lifespan of 25 to 30 years for females and 15 to 20 years for males. (Lima & Paez 1997)

South American fur seals are social mammals. These seals form rookeries on rocky coasts, where breeding takes place. Competitive interactions between this species and South American sea lions, Otaria byronia, are rare because their habitats don’t overlap. Females remain in the rookery year-round, but not much is known about the movements of males and sub-adults. Groups of 15 – 20 seals have been observed travelling together offshore, where they compose rafts of animals. They frequently groom while floating on the surface. A satellite telemetry study of females showed that a shift in foraging behavior occurred throughout the year. When pups were still young, mothers stayed close, returning daily from foraging for food. As the pups grew, the forays were extended in distance and time. During the breeding season, males compete more for territorial areas than for individual females. In tropical parts of their range, the seals are forced to move between the rookery and the ocean to cool off. The frequent movement of females is a reason that many pups are displaced and become victimized by other aggressive females. In a 1988 study in Peru, it was found that play was an important part of growing for pups, but involved large costs. Though 6.1% of the daily time budget of pups was involved with play, 84.6% of those preyed upon by sea lions were killed while at play. (Trillmich 1989, Harcourt 1991, Majluf 1992, Jefferson, et al. 1994, Parker 1996, Falklands Conservation 2000)

The diet consists of anchovies, sardines, and mackerel, along with cephalopods, crustaceans, bivalve mollusks, and gastropods. Arctocephalus australis individuals usually forage at night and will dive for 3 minutes to an average depth of 29 meters, but will reach a maximum time of 7 minutes and 170 meters in pursuit of food. Numbers of anchovy can fluctuate abruptly in the Pacific Ocean, where El Nino events occur every 2 – 7 years. This will affect reproductive success of females. (Reeves, et al. 1992 & Majluf 1992)

No information was available on anti-predator adaptations. South American fur seals are preyed on by large sharks, such as great white sharks (Carcharodon carcharias), orcas (Orcinus orca), South American sea lions (Otaria byronia), and by humans. Their large size will protect them from many, smaller predators.

(Reeves, et al. 1992 & Couturier 1996)

South American fur seals are important members of the ecosystems in which they live. They are important predators on fish species and other marine organisms, and are preyed on by the largest predators in these oceans, great white sharks(Carcharodon carcharias) and orcas (Orcinus orca).

Fishermen may complain that these fur seals compete with them for valuable fish, such as mackerel and sardines, though their true impact on fisheries is likely to be negligible.

South American fur seals have been hunted for centuries, both by indigenous peoples and by whalers. Early peoples in the area of Tierra del Fuego, as well as in Uruguay and Peru, used the seal for meat and clothing. Commercial hunting of these seals began in Uruguay as early as the 1500s, mainly for their skins and oil. The oil was used for lighting and later as a medicinal for tuberculosis. Hunting pressure was unregulated until the 1940s, when a population decline in Uruguay was evident. Since then, take has had an annual limit, which now is about 7,000 – 12,000 seals, limited to young males. In Peru, commercial hunting of these fur seals continued until 1959, when it was prohibited. In Chile and Argentina, the seals were hunted and used for bait to catch king crab. Today, commercial hunting is only done in Uruguay. (Reeves, et al. 1992, Jefferson, et al. 1994)

The population of South American fur seals in 1999 was estimated at 390,000, a drop from a 1987 estimation of 500,000. Although overall species numbers are healthy, the downward trend is causing some concern. Uruguay has the largest numbers of seals along its coast, numbering over 200,000. Peru’s number dropped to only 40 in the 1940’s, but subsequent protection has brought the numbers back up to about 20,000 by the 1980s. Because of the El Nino events and general overfishing along the Pacific coast of South America, the population in the Pacific is not recovering as quickly as it could. Presently, Peru has had a problem with fishermen illegally killing South American fur seals, claiming that the seals interfere with fishing operations and diminish the anchovy numbers. In the Falkland Islands, where commercial hunting greatly reduced their numbers, the population now contains about 15,000 seals. There are approximately 40,000 seals in Chile and 3,000 in Argentina. Arctocephalus australis is on appendix 2 of the CITIES. (Reeves, et al. 1992, Couturier 1996, Jefferson, et al. 1994)