Found only in Australia and one of the most endangered pinnipeds in the world, there are estimated to be 10,000-12,000 Australian Sea-lions between The Pages Islands in South Australia and Houtman Abrolhos off the Western Australian coast. The species mostly inhabits islands but also a few mainland sites, the principal breeding colonies being located at Kangaroo Island and Dangerous Reef in South Australia.

This genus of Australian Sea-lion has one species. The male is blackish to chocolate brown with a prominent white mane, the female is slivery-grey. These photographs were taken on Kangaroo Island (SA coast).

The snout is blunter than in fur-seals.

The species was heavily hunted for its hide and oil in the 18th and 19th centuries before which its range extended as far as the islands in Bass Strait. The Australian sea lion is now listed as Rare under South Australian legislation where it has received full legal protection since 1964 and has Special Protected Species status in Western Australia where it has been legally protected since 1892.

Evidence is mounting that the size of the Australian Sea-lion population has levelled off and may be declining. Entanglement in fishing nets, particularly shark nets, and crayfish pots is one of the main threats to the species.

The eared seals are very social mammals. They congregate into groups, which become larger during the mating season.

Australian Sea-lions are opportunistic feeders taking a wide variety of prey, particularly squid, octopus, scale fish and some crustaceans.

The pregnant female comes ashore about three days before giving birth to a single yong, and there is strong evidence of an 18-month breeding cycle.

Australian Sea-lions haul out and breed on rocks and sandy beaches, mainly on offshore islands. A long breeding season of about five months means that the males, unable to protect their territory continuously, spend up to four weeks ashore at a time maintaining small female groups, normally containing 4-6 females, and are very aggressive towards each other. The Australian Sea -ion has a unique breeding cycle amongst the pinniped species, the females giving birth to their pup after a 17.3-17.7 month cycle. A particular female's pupping season occurs in alternate summers and winters or in alternate springs and autumns, and the pupping season for different Australian Sea-lion colonies takes place at different times.

The male establishes its territory and harem and very agressively defends them. Mating occurs four to nine days after the young, which is suckled for at least 12 months, is born.

Pups have a mortality rate of about 23% in their first 6 months and between 40 - 50% in the first 2 years. Bulls account for 20% of the mortality rate in pups in the first 6 months, mainly by trampling when challenging another bull. Females come into season when the pup is only about 7 days old, and is still very vulnerable to being harmed by the bulls. Other contributing factors are predation by sharks, poor mothering, disease, breeding areas being inundated by storms/high tides and pups getting jammed in rock crevices. Adult animals are exposed to many dangers in their lives and only about 30% of the pups from each breeding season will reach maturity.

There is no evidence of migration or seasonal movements, apart from some movement of adult and subadult males on the west coast of Western Australia, and it appears that Australian sea lions tend to stay around their haulouts and breeding sites.

Adult males measure between 2-2.5m in length and weigh 250-300kg.

References:

Ronald Strahan, A Photographic Guide to Mammals of Australia, The Australian Museum and New Holland Publishers, 1995

Seal Conservation Society - http://www.pinnipeds.org/species/auslion.htm

Seal Bay - http://www.environment.sa.gov.au/parks/sealbay/sealion.html

Museum of Zoology, University of Michigan - http://animaldiversity.ummz.umich.edu/accounts/neophoca/n._cinerea$narrative.html