A long-nosed fur seal found dead at Beachport on Wednesday has tested positive for H5 bird flu, the first confirmed mammal fatality on the Australian mainland and a new escalation for the outbreak. The animal was reported to an official hotline with no visible injuries, and laboratory analysis later confirmed the H5 detection.
The case follows a string of large bird die-offs in South Australia, where Premier Peter Malinauskas announced three mass mortality events among greater crested terns involving more than 1,000 birds on offshore islands. Federal agriculture minister Julie Collins described the seal infection as "not unexpected", saying the appearance of a mainland mammal case was anticipated and that "it was not possible to avoid significant losses".
"An infection of this individual animal is likely to have occurred due to exposure to infected wild birds or the environment that they share," Collins said. She warned that where more dead wild birds are found, authorities expect increased reports of affected marine mammals.
Authorities have recorded 298 events across the country, with 183 in South Australia, 86 in Victoria, 11 in New South Wales, 10 in Western Australia, seven in Tasmania and one in Queensland. Officials continue to stress the risk of human transmission remains low, and they urge the public to avoid sick or dead birds and report sightings to birdflu.gov.au.
The H5 strain involved is a highly pathogenic virus that has killed millions of birds globally and has crossed into several mammal species, including elephant seals. Federal assessments list long-nosed fur seals and the endangered Australian sea lion among species at very high risk from the virus. Jack Gough, chief executive of the Invasive Species Council, warned the spread to sea lions could be an "extinction level event" and said, "We are still just at the early stages of this devastating virus, and the bad news is going to keep coming for our wildlife as it spreads around the continent and between species."
South Australia also confirmed a little penguin from Kangaroo Island tested positive for H5. Environment minister Emily Bourke said the state will work with the federal government to consider whether an experimental vaccine from the United States could be used for affected mammals, noting "It is not an off-the-shelf vaccine that’s been approved, and we have to be taking into consideration the risk [of undertaking] the vaccination program in our mammals".
Conservation groups are pressing for more funding to protect threatened species. Australian Marine Conservation Society campaign director Alexia Wellbelove called for a $200m wildlife resilience fund, arguing existing preparedness funding cannot manage active spread across multiple species and states.
In Tasmania, authorities said 51 little penguins found on King Island were "assumed to" have died from H5, though officials stopped short of declaring a mass mortality event. A sample from one penguin at the Port of Grassy tested positive, a second returned an inconclusive result, and both samples were sent to the Australian Centre for Disease Preparedness for further testing. Wes Ford, the state's incident controller for the bird flu response, said remaining carcasses were unsuitable for testing and that monitoring and surveillance work will guide the next steps.
State and federal agencies now face decisions on scaling monitoring, managing affected colonies, and whether to deploy experimental vaccination protocols under careful risk assessment. In the short term, officials will continue surveillance and public messaging while laboratory results and field reports determine where losses deepen next.
