Fur seals have large eyes, a pointed face with whiskers and sharp teeth. The Australian Fur Seal, Arctocephalus pusillus doriferus is the largest of all the fur seals. It has a broad head, pointed snout and long backward sweeping facial vibrissae (whiskers). The body is robust and covered in thick brown layered hair except on the front and back flippers. The Australian Fur Seal is sexually dimorphic (males and females are visibly different). The males are larger than the females and when mature carry a dark mane of coarse hair. They have a set of carnivore-like teeth similar to those of a large dog or bear. Like all members of the Family Otariidae (Fur seals and sea lions) they can raise their body onto their front flippers to move around on land.
The Australian Fur Seal has a relatively restricted distribution around the islands of Bass Strait, parts of Tasmania and southern Victoria. They can be seen hauling out (coming ashore) on islands off South Australia and areas of southern New South Wales such as Montague Island with the occasional animal appearing as far north as the mid north coast of New South Wales.
As it is closely related to the South African Fur Seal, its populations worldwide are reasonable secure although it is occasionally commercially hunted in South Africa. In Australia it is fully protected although its numbers are probably still only half those of the historic pre sealing days. It continues to be vulnerable to disturbance at its breeding sites and suffers some loses as a result of conflict with commercial fishing operations.
Australian Fur Seals frequent coastal waters and oceans. Their preferred habitat especially for breeding is rocky islands, which include boulder or pebble beaches and gradually sloping rocky ledges.
Australian Fur Seals feed on a variety of bony fish species plus squid and octopus. They are voracious and skilful hunters in the water and are not adverse to taking advantage of situations where fish are corralled by nets and fish farms.
With its streamlined shape and strong flippers, the Australian Fur Seal is an agile swimmer and can dive to depths of 200 m to catch fishes and squids. Despite its cumbersome appearance, it is also quite mobile on land, even over rocky terrain.
Fur seals differ from other seals (true seals) because they have external ears and the ability to use all four limbs to move across land. Also, fur seals have two layers of fur while other seals have only one layer.
Australian Fur Seals come ashore each year and form breeding colonies. The adult males come ashore first and establish territories. Females congregate within these areas and are defended by the resident male often with considerable aggression towards the females and other males. Females spend most of the gestation period at sea, coming ashore just before the birth of a single pup (sometimes two) between October and December. Females generally mate again 6 – 10 days later.
The Australian Fur Seal has what is referred to as ‘delayed implantation’, which means the fertilised egg remains dormant for some time before implanting and resuming development. This ensures that the pups will always be born in summer when chances of survival are highest because of the warmer weather and abundant food supply.
The pup population suffers a high mortality rate in those first two months of life especially when the mothers are away at sea feeding. Pups are weaned at four to six months old but may still remain with the mother for a further six months or more.
In the wild, seals are eaten by several species of sharks including the White Shark.
During the 1800s the Australian Fur Seal was heavily hunted for its coat and the population dropped from several hundred thousand to only 20,000. Entanglement in discarded fishing gear is also a threat. All Australian marine mammals are protected and the Australian Fur Seal population is making a recovery.
- Species: pusillus doriferus
- Genus: Arctocephalus
- Family: Otaridae
- Order: Pinnipedia
- Subclass: Eutheria
- Subphylum: Vertebrata
- Kingdom: Animalia
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.
Australian fur seals, Brown 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.
Brown Fur Seal
The brown fur seal (Arctocephalus pusillus) is a large seal species of Australia and South Africa. The adult male brown fur seal has a light greyish-brown body and a dark brown belly, with a mane across the neck and shoulders which becomes lighter in colour with age. The female brown fur seal is browner than the male, but still has the darker brown belly. Pups are born black, and juveniles are generally the same colour as the female, but have lighter fur below the jaw and behind the ears.
The head of the adult male brown fur seal is larger and broader than that of the female, and has a low brow, which is lacking in the female. Both sexes have a pointed snout, forward-facing nostrils, and moderately long whiskers which extend past the ears. The ears themselves are small and stick slightly out from the head. The paddle-shaped flippers of the brown fur seal are large and thick, and appear black when wet. The ability to turn the flippers forward helps distinguish fur seals from ‘true’ seals (species in the family Phocidae).
The brown fur seal is split into two recognised subspecies, the Cape fur seal (Arctocephalus pusillus pusillus) and the Australian fur seal (Arctocephalus pusillus doriferus). These two subspecies are genetically and behaviourally very similar, but occupy distinct ranges.
Northern Fur Seals
Size Males can weigh up to 600 pounds and grow up to 7 feet long. Females weigh up to 120 pounds and are generally 4.5 feet long.
Diet Squids and small schooling fish such as walleye pollock and herring
Lifespan 15 – 25 years
Range Northern fur seals are widely distributed in the North Pacific Ocean. Their primary breeding location is the Pribilof Islands off the coast of Alaska.
Habitat Fur seals are migratory, spending about half of each year out at sea. While at sea, they sleep by floating at the surface, often with their flippers up and
out in what is called the jughandle position.
Predators Adult fur seals are hunted by orcas and large sharks.
Relatives Northern fur seals and sea lions are in the same family known as “eared seals.” They are known for their ability to rotate their flippers under them and “walk”
Family life Mating occurs between June and July on remote island beaches called rookeries. Pups are born one year later on the same beach. They are able to live independently after four months.
Conservation status Vulnerable Fur seals were commercially hunted for their pelts until the practice was banned in 1966. The population has continued to decline since then. The reasons for the decline in fur seal populations are unclear, but possible factors include overfishing, entanglement in fishing gear, climate change and pollution.
Australian fur seals, Brown fur seals
New Zealand fur seals
New Zealand fur seals (Arctocephalus forsteri, or kekeno) are found around New Zealand and its offshore islands, and southern Australia. Excavation of midden sites shows that when Polynesians arrived about 1300 AD, fur seals became an important source of food. By the time Europeans arrived in the late 1700s the seals had been all but wiped out, save for colonies on the South Island’s sparsely inhabited south-western coast. The pale-faced sealers finished off the remaining few and severely depleted numbers on the Chatham Islands, Bounty Islands and subantarctic islands – all for their pelts and the oil rendered from their blubber.
On the tiny Bounty Islands, numbers went from 52,000 in 1800 down to five by 1831. There has been considerable recovery since: 16,000 were estimated there in 1980.
Their prey is fish, cephalopods such as squid and octopus, and crustacea including krill. Most dives last one or two minutes. Fur seals will forage up to 200 kilometres beyond the continental slope, often diving as deep as 200 metres.
The seals breed on steep boulder beaches with plenty of crevices and tidal pools. Their layer of fat and thick fur coats, which enable them to endure long periods in water, can cause overheating on land. Crevices provide shade, and tidal pools a place to cool off.
The dominant male mates with numerous females, so many males do not get a chance to breed in every season. They often have sites where they haul out (rest), away from the breeding colonies. These sites may become breeding colonies if females visit them.
Adult males are the first to arrive at the breeding colonies, from late October to early November. They establish territories that they defend aggressively, and remain on land, fighting but not feeding, until mid-January. This inter-male competition has promoted the evolution of large males, weighing up to 185 kilograms (an average female weighs 40 kilograms).
Females arrive from foraging at sea in late November, and give birth to a single pup (conceived the year before) by early January. About eight days later she will mate – usually with the dominant male. The female does all the nurturing of the newborn. She stays with the pup constantly for about 12 days, then alternates between feeding at sea and suckling. As the pup grows, the mother needs more food to make enough milk. Pups are weaned in July or August, and the pregnant females go to sea to fatten once again. The young pups then head out to sea, coming ashore at times. Females start breeding at around four years.
After fertilisation, the embryo’s growth is suspended for two to four months. It then implants in the mother’s uterus, and development resumes. This enables females to give birth and then mate during the same episode ashore, while still allowing for a normal gestation of about nine months. The female can therefore recover from rearing one pup before developing the next. The pup’s birth is also synchronised with the female’s return to the breeding ground the next season.
Delayed development occurs in all New Zealand’s seals, and most likely in all seals. The longest known life span of a New Zealand fur seal is 15 years.