Australian Sea Lion

Australian sea lions are sparsely distributed across their range, from the Houtman Abrolhos Islands (28°S, 114°E) in Western Australia, along the southern Australian coast to The Pages Islands (35°46'S, 138°18'E) in South Australia. Sixty-six breeding colonies have been identified, with 28 in Western Australia and 38 in South Australia. Most breeding colonies exist on offshore islands, with the exception of Point Labatt in South Australia, Baxter Cliffs (west of Twilight Cove) in Western Australia, and the Bunda Cliffs, Great Australian Bight, which straddles the border between the two states. About 42% of the total known population is found within the three largest colonies east of Port Lincoln; Seal Bay (on Kangaroo Island's south coast), The Pages, and Dangerous Reef (in Spencer Gulf). The species' breeding range has contracted as the population has fallen. Now-extinct breeding colonies previously existed in the Bass Strait, particularly on Clarke Island and adjacent islands in the Furneaux Group. The Abrolhos Island breeding colony is believed to be much smaller today than it was prior to European settlement. Kangaroo Island's northeasterly coasts, in addition to some islands near Perth and Albany, once hosted now-extinct breeding colonies.

Australian sea lions have been described as opportunistic, benthic foragers. Limited stomach-content and faecal analyses have identified a wide variety of prey in the diet of the Australian sea lion, including teleost fish (including blue-throated wrasse and whiting), squid, cuttlefish, octopus, sharks (including Port Jackson sharks), rays, southern rock lobster, other small crustaceans, and little penguins. Regurgitate and stomach samples from Australian sea lions at Seal Bay contained hard parts consisting predominantly of benthic taxa. This supports previous evidence that this species forages primarily on neritic, benthic prey, many of which are nonmigratory. For the cephalopod component of the Australian sea lion diet, octopus and giant Australian cuttlefish made up the greatest biomass of prey taxa. Although the Australian sea lion feeds off seasonally available prey such as semelparous cephalopods, it also exploits prey species that are available throughout the year, such as southern rock lobster and many fish species. Observations from the 1930s in Western Australian noted that Australian sea lions seemed to be subsisting on little penguins during the summer, and that their regular diet did not compete with commercial fisheries. Also in the 1930s, the animal was described informally as "rather fond of penguins". They were known to feed on little penguins in the 1960s.