South Australia has confirmed the first case of H5 bird flu in an Australian sea lion at Seal Bay on Kangaroo Island.
The sea lion had been recovering from a shark attack when it died.
Authorities say bird flu was the cause of death, not the shark injuries.
Australian sea lions exist nowhere else in the world, and have been classified as endangered.
It comes as several outbreaks of the virus have wiped out large shares of other seal populations around the world.
Background
Bird flu (H5N1) has been spreading through Australian wildlife since it was first detected on the mainland in June.
The virus is called bird flu because it was first detected in birds, but it can spread to other species.
In August, SA recorded the first confirmed bird flu case in a mammal on the mainland: a long-nosed fur seal.
Since then, more fur seals and little penguins in the state have also tested positive.
As of 11 September, 521 “events” had been confirmed nationwide.
An event can range from one to hundreds of infected animals at one location.
Sea lions
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There are fewer than 12,000 Australian sea lions left.
About 85% live in SA, with the rest in WA.
The population was already declining before bird flu arrived.
In other regions, bird flu has devastated seal populations.
Thousands of baby seals died on Heard Island, a remote Australian territory 1,700km north of Antarctica, after the virus reached there in late 2025.
New case
The sea lion was found at Seal Bay, one of Australia’s last major sea lion colonies and a popular tourist stop on Kangaroo Island.
It had survived a shark attack, but testing showed bird flu was the actual cause of death.
At a press conference on Sunday, SA Environment Minister Emily Bourke said the State Government had seen “quite a number of mammal cases” but that the Australian sea lion is of note because it is the “rarest seal found in Australian waters”.
Response
Tours at Seal Bay are currently restricted to the boardwalk rather than the beach, to limit contact with the colony.
Authorities have also been trapping feral cats around the colony, as they can spread the virus.
Bourke said SA would be open to trialling an experimental vaccine, if it gets federal approval.
