The Australian Sea-Lion is a large sea mammal growing two and a half metres in length and weighing up to 220kg. Its body is streamlined like a torpedo to enable it to glide through the water. The male, called a bull, has a very thick neck and powerful shoulders. The forelimbs and hind limbs are flippers which are used for swimming. The hind limbs will move up and down propelling the Sea-lion forward, in a similar way to a dolphin’s tail. The males are chocolate brown in colour while the females are silvery in colour on their backs with cream down their sides.
Distribution & Habitat
Australian Sea-lions are found in and around the southern and south-western waters of Australia, although some have been recorded as far north as the mid-north coast of New South Wales. Their thick fur allows them to live in extremely cold water.
Sea-lions come ashore to breed and rest on both sandy beaches and the rocky coastlines of Australia’s southern islands and mainland.
The Australian Sea-lion has an 18 month breeding cycle which is long in comparison to other Sea-lion species. It is not uncommon for neighbouring breeding sites to be on entirely different breeding schedules to each other and inter-breeding between sites occurs but is not common.
Male Sea-lions have numerous mates and establish territories around their females, herding them in an effort to keep them close until they are ready to breed.The pups are born in gullies or crevices in the rocky sections of the beach and the mothers will suckle their pups for 15-18 months, often stopping only a month before giving birth again.
The aggressive nature of the Australian Sea-lion can make life very tough for the newly born youngsters. Many pups have been killed by bite wounds inflicted by aggressive males protecting their territory. As a result of this, it is not uncommon for mothers to care for their young for as long as three years.
The diet of the Australian Sea-lion is mainly fish, squid and crustaceans. The occasional penguin or other sea bird will be eaten if the opportunity arises. Speed and surprise are the two elements used by this animal to catch its prey. The flippers are used to propel the animal after its food. Fish and squid are caught in the mouth and quickly eaten as the Australian Sea-lion doesn’t chew its food, swallowing it whole.
Australian Sea-lions are considered non-migratory and are believed to spend most of their lives in and around their original breeding colony.
Males will defend their territories with a variety of sounds including growling and barking, often fighting with rival males.While their mothers are at sea foraging, the young pups will spend their time resting or playing at the shoreline and in tidal pools, eventually developing the skills and confidence to venture out into deeper waters on their own.
Sea-lions are powerful swimmers and often “porpoise” out of the water when escaping predators or travelling quickily at the surface.They feed at sea and forage for their food on the sea floor, holding their breath and diving to over 100 metres. They are able to remain underwater for over eight minutes at a time.
The Australia Sea-lion is rarest Sea-lion in the world. In 2008 the Australian Sea-lion was listed as an endangered species due to the fact that its already small global population continues to decline.
During the last century the Australian Sea-lion was heavily hunted for its fur, depleting its population significantly. Hunting is now illegal and is strictly policed. Australian Sea-lions are still under threat as victims to fisheries bycatch, becoming entangled in gillnets and fish traps.
These threats are well understood and reversible but have not stopped. Even small numbers of Sea-lion deaths from fisheries bycatch can have a significant impact on the population sizes of already small and isolated breeding colonies.
Unsustainable fisheries also pose a big threat for the Australian Sea-lion as they compete directly with the animals for food. The ocean is such an interconnected ecosystem that the depletion of one species can have huge impacts on many of the other species.
The breeding sites are fragile environments, important for the survival of the species but are sensitive to human disturbance and therefore also require protection.
This species was listed as endangered in 2008 and is currently protected in Australia by numerous conservation agencies and laws. Fisheries are monitored for their impacts on the Sea-lions and recent conservation inniatives have been focussed on education within the industry aimed at reducing bycatch.
The National Parks and Wildlife Service on Kangaroo Island in South Australia is working to protect the Australian Sea-lion by restricting visitors to boardwalks along the cliff tops where they can still view the Sea-lions without disturbing breeding sites.
Taronga’s conservation work
Taronga Zoo, in association with the Universities of Sydney and NSW, operates the Australian Marine Mammal Research Centre which runs a scientific and educational program on marine mammals in Australia. The aim of this project is to find out more information about these unusual animals and devise strategies that will ensure their survival. Taronga Zoo also cares for sick and injured Australian Sea-lions that have beached on the coast of New South Wales. After veterinary treatment and rehabilitation they are released into their natural habitat.
How you can help
You can help by understanding the issues and making responsible choices. Buying seafood that comes from sustainable fisheries is important. To do this, ask the seller questions about the seafood you want to buy. Buy locally caught seafood and avoid deepwater or long-lived species that are often overfished.