The Australian fur seal (Arctocephalus pusillus doriferus
) is the world's fourth-rarest seal species and, with its conspecific, the Cape fur seal, it is the largest fur seal in the world. Hunted to the brink of extinction last century, population recovery has been slow, and these seals are now wholly protected.
The Australian fur seal is found from the coast of NSW, down around Tasmania to Victoria and South Australia. It is the most common seal in Tasmanian waters and breeds on small isolated rocks in Bass Strait between October and January. It also hauls-out at various rocky areas around the Tasmanian coastline, especially outside the breeding season when many seals disperse from the breeding colonies. See the map of sites around Tasmania where to observe fur seals
It isn't always easy to tell the sexes apart, although the adult males are much bigger animals than adult females, with large heads and heavily-muscled necks and chests. Adult females average 125-170 cm in length and weigh between 50-120 kg. Cows are slender, silvery-grey on the back, with a creamy-yellow throat and chest, and a chocolate brown belly. Newborn pups are almost black on the back and grey/light-brown on the belly, moulting after three months.
Adult male seals can grow to 200-225 cm and weigh 220 kg to 360 kg. Bulls are usually dark grey/brown, with a mane of coarse hair on neck and shoulders. Young seals of both sexes have grey-brown backs and yellowish belly fur. The dense coat is made of woolly underfur and long, coarse outer hairs to trap air which waterproofs and insulates the seal. Like all seals, they moult each year, replacing their old fur with new growth. A layer of fat assists with warmth and streamlining.
The Australian fur seal eats mainly fish and cephalopods (squid, octopus and cuttlefish). Of the nineteen fish species known to be consumed, Jack Mackerel, Redbait and Leatherjackets form the main prey items. Of the 11 known cephlapod species eaten, the most frequently consumed is the Gould's Squid (Notordarus gouldi).
Females give birth to a single pup which is fed on thick, rich milk. Pups are born in November-December, and usually weaned 10 to 11 months later, although some cows may suckle a pup for up to four years. Once a cow gives birth for the first time, she is practically in a continuous state of pregnancy/lactation for the rest of her life, with maybe only a few weeks off between weaning last season's pup and having another.
Australian fur seals breed on nine rocky Bass Strait islands, but because seals only come ashore to rest and breed, it is impossible to know exactly how many there are. Based on counts at the breeding colonies each year, scientists estimate there are about 5,000 pups born in Tasmanian waters each year. However, not all pups will survive to become adults. Pup mortality for most fur seal species is between 3 to 30%, however, storm induced mortality can be as high as 70% for this species. This natural mortality continues throughout the life of the seal, but at a lower level than that of the pups. Seal mortality also occurs as a result of human activities such as deliberate persecution through shooting, fisheries bycatch and entanglement in plastic, and other non-biodegradable materials.