Antarctic fur seals
Scientific name: Arctocephalus gazella
Physical description and related species
Fur seals are the smallest seals and closely related to dogs and sea lions, able to walk on all fours. The common name of fur seal includes several species: Antarctic fur seals, subantarctic fur seals and New Zealand fur seals.
They have teeth, whiskers and thick fur, similar to the coat of a dog. They don’t have layers of fat like other seals but rely on their thick fur coat to keep them warm.
Adult males can weigh up to 200 kg, adult females weigh about 40 kg, and pups weigh between 3–7 kg at birth. Occasionally these seals are pale blonde.
Distribution and abundance
At Macquarie Island three species of fur seal occur: Antarctic fur seals (Arctocephalus gazella) and subantarctic fur seals (Arctocephalus tropicalis) which both breed there and New Zealand fur seals (Arctocephalus fosteri), which occur in large numbers but do not breed.
At Heard Island the population is increasing. In 1992 there were about 250 pups born at Heard Island, and by March an influx of adult males and juveniles increased the numbers to over 21 000 fur seals.
Threats: In the last century fur seals were killed for their skins, and many populations were wiped out. The first pups born post-sealing were reported from Maquarie Island in 1955 and from Heard Island in 1963. Today fur seals can become entangled in marine debris such as polypropylene packaging bands, nylon string and fishing nets.
Conservation status: least concern
Fur seals breed on land, mainly on subantarctic islands south of the Antarctic convergence including the South Orkney and South Shetland Islands, South Georgia, South Sandwich Islands, Bouvet Island, Iles Kerguelen, and Heard Island, with only three colonies (on Marion Island, Iles Crozet, and Macquarie Island) lying north of the convergence.
Male Antarctic fur seals establish territories through fighting with other males. The dominant bulls control a portion of a beach from the waters edge to the vegetation behind. Territorial bulls give off a strong sweet musk odour during the breeding season.
Female Antarctic fur seals are not gathered into the harems as elephant seals are. Females are gregarious and choose the best beach site on dry shingle. Males actively discourage females from moving to other territories.
Pups are born from late-November to early-January and are suckled for about four months.
Diet and feeding
These active seals are very successful at finding concentrations of food, some of them visiting Antarctica to feed on krill. Fur seals at South Georgia feed mainly on krill while at Heard Island and at Macquarie Island they feed mainly on fish, and some squid.
Female fur seals forage close to the islands while caring for their young. Male fur seals have no parental responsibility and forage significantly further afield. At South Georgia, females dive to around 30 m but can exceed 100 m, remaining submerged for 2–5 minutes.