Antarctic Fur Seal
The Antarctic fur seal (Arctocephalus gazella) is distinguished from true seals by the presence of external ears and the ability to bring their rear flippers underneath their bodies to enable them to stand on all four limbs. For this reason, fur seals are more closely related to sea lions than true seals, and are more capable of moving on land.
Antarctic Fur Seal Life span
Antarctic Fur Seal Statistics
Body length: Males (bulls): 1.6-2m, Females (cows): 1.2-1.4m. Weight: Males: 90-210 kg, Females: 25-55 kg.
Antarctic Fur Seal Physical Description
The pups are born with black fur, which develops into a grey-brown to light brown coat when they reach adulthood. Females tend to have a creamy-coloured chest.
This fur seal is a fairly large animal and has a short and broad snout compared with others in the family. Adult males are dark brown in colour. Females and juveniles tend to be grey with a lighter undersides. Colour patterns are highly variable, and some scientists believe some hybridisation with subantarctic fur seals has occurred. Pups are dark brown on birth, almost black in colour. About one in 1000 Antarctic fur seals are pale ‘blonde’ variants.
Males are substantially bigger than females. Antarctic fur seals grow up to 2 m (6.5 ft) long and weigh 91 kg (201 lb) to 215 kg (474 lb). Males live for about 15 years and females up to 25.
Antarctic fur seals appear to act alone when foraging and migrating. Males breed polygynously; a strong male may have more than a dozen female partners in a single season. Territories are established on breeding grounds in October to early November, when the musty-smelling males are extremely aggressive in defence of their harems. Females gestate for just over a year – giving birth in November or December. Pups are weaned at about four months old. Juveniles may then spend several years at sea before returning to begin their breeding cycles.
The usual food supply is krill and fish, of which each Antarctic fur seal eats about a ton in a year. Due to the enormous and growing populations of these seals, their food is a significant proportion of South Georgia’s krill and fish stocks.
Antarctic Fur Seal Distribution
The largest populations are found south of the Antarctic polar front, and 95 per cent of Antarctic fur seals breed on South Georgia.
The Antarctic fur seal breeds in summer on islands ranging from South Georgia at 70° W round to about 80° E (Kerguelen Islands). Additionally, there is a breeding ground at Macquarie Island, 165°E – south of New Zealand. All these islands lie between 45° S and 60° S. The animal’s winter range is not known. During these long dark months, the seal spends its time almost surely at sea close to the Antarctic ice. Not disimilar to the Adelie Penguin.
A population count is due in 2007 or 2008, and estimates can only be very rough until this is carried out. Best guesses suggest there may be two to four million individuals breeding at South Georgia and 15,000 at Heard Island. The concentrations at South Georgia are the densest aggregations of marine mammals on earth. These populations are believed to have grown to such levels because the removal of whales by the intensive whaling of the 20th century left a surplus of krill. Other islands in Antarctic waters may have a few hundred to a thousand such seals
Antarctic Fur Seal Diet
The main component of the Antarctic fur seal’s diet is krill, but they will also hunt fish and squid.
Antarctic Fur Seal Behavior
They feed mostly at night, and dive to depths of 30-40m, although depths of 250m have been recorded. Leopard seals hunt Antarctic fur seal pups, and killer whales are also a threat.
Males arrive at the breeding sites from late November to January. They will fight for access to females and a typical harem contains five females.
Antarctic Fur Seal Reproduction
For about 4 months after the pup is born, the mother goes through a cycle of feeding at sea for 3-5 days and returning to feed her pup for 1-2 days.
Antarctic Fur Seal Conservation status
Antarctic fur seals are not considered to be threatened. There are estimated to be 1.5 million individuals, although commercial hunting for fur in the 18th and 19th Century nearly led to their extinction.