First case of bird flu in endangered sea lion

A case of bird flu has been detected in an Australian sea lion for the first time, raising concerns for the species' already dwindling population.

A sea lion at South Australia's Seal Bay on Kangaroo Island tested positive for the highly transmissible disease, authorities confirmed on Sunday.

Endangered sea lions are the rarest species of seal in Australia, with more than 80 per cent of the estimated total population of 10,000-12,000 found in SA.

The development has sparked fears of a possible extinction event after seal colonies worldwide were left devastated by the virus.

The seal that tested positive had also been attacked by a shark and may have been more susceptible to the disease as it was recovering, SA Environment Minister Emily Bourke told reporters.

"We found that it was actually not the shark attack that killed the sea lion; it was the bird flu case," Ms Bourke said.

"When we look around the world in regards to the impact on sea lions and seals, there's been a devastating impact.

"We know that this is going to be not the first and only case in our sea lions."

In some cases, populations of seals impacted by the disease globally had experienced reductions in pup numbers of up to 95 per cent.

A long-nosed fur seal that died of the virus in August at Pages Conservation Park, nearby Kangaroo Island, was Australia's first recorded case of the disease in a mammal.

Authorities are scrambling to protect the seals, with hundreds of feral cats around Seal Bay trapped to prevent them contributing to the spread of the virus.

With no approved bird flu vaccines currently available for mammals, more than 400 seal pups were instead vaccinated against hook worm, to give them the best chance possible to fight off infections.

"We just want to take our make our seals as resilient as possible," Ms Bourke said.

Even before the arrival of bird flu, the sea lion population on Kangaroo Island was declining by around two per cent every year due to other factors.