EARED SEALS

Antarctic Fur Seal (Arctocephalus gazella)

The Antarctic Fur Seal (Arctocephalus gazella) is found in the Southern Ocean in Antarctic waters. Confusingly, the large majority of them breed on the subantarctic island of South Georgia, but they can also be found on the Antarctic continent, as well as widely spread across other subantarctic islands, and turning up sometimes in southern South America and Australia. Again, the species is named for their ‘bear head’, and the ‘gazella’ part comes from a German naval vessel who collected the first specimen. A. gazella are thought to be the most abundant fur seals in the world, and thus are classified as Least Concern. Estimated population size = 4,634,301. This is a very crude estimate arising from the best approximations available at the moment though, as reliable censuses are lacking for many of the breeding populations.
A. gazella are medium large and sexually dimorphic fur seals (males up to 2 m long/ 230 kg, females up to 1.4 m/ 51 kg). Their bodies are heavy, with long necks and proportionally short flippers, for a fur seal. Males of the species have raised crowns with thick necks, broad shoulders, and dense manes, while females are more streamlined. Both have smallish heads for their size, with short, upwardly-pointing muzzles, and very long, cream whiskers. Colouration tends to be dark brown in males, with grizzled silver-blond fur around their crowns and down their necks. Females are generally paler, from greyish to brown, darkest on the dorsal with lighter undersides and face. Less than 1% of A. gazella are leucistic and sport a striking honey-blonde coat. This blonde morph colouration is characteristic in South Georgia, but has been sighted elsewhere.
Feeding behaviour:
Throughout much of the studied areas, A. gazella primarily eat krill. Where this is not richly abundant, for example outside of South Georgia, they are known to rely on foods such as cephalopods and deep-water fish, including icefish and lanternfish, fished at night when they migrate up to shallower waters. A. gazella is not a particularly deep diver. Seasonal fluctuations are evident in the diet of this species, and examples of predation on penguins have also been noted.
Breeding behaviour:
Sexual maturity – males 3-4 years old/ females 3-4 years old.
The males of this highly polygynous species arrive at the breeding beaches a good 2-3 weeks before the females in order to obtain territories which will be defended vocally, posturally, and physically, sometimes to the death. Mating occurs in the summertime (November-December), between 1 male and up to 20 females, and after a year’s gestation, pupping occurs in November and December. Pups are born with black fur, and nursed continuously for a near enough a week, before the mother begins foraging trips at sea. By 2-3 months of age, the pups moult and acquire a silvery-grey pelage, and they are weaned at just 4 months old. Adults also moult in the late summer/ early autumn. After this time the rookery breaks up. Hybridisation has been recorded with both Subantarctic Fur Seals and New Zealand Fur Seals. Female A. gazella have been known to live to their mid-twenties, while males typically reach about 15.
Formally considered a subspecies of Arctocephalus tropicalis, A. gazella are now known as a species in their own right, with no other subspecies.

Photos: (1) Antje Kakuschke (2) Hanna Michel (3) Amy Van Vise/ NOAA

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