Bird flu likely killed hundreds of seal pups on sub-Antarctic island

Australian scientists have found hundreds of dead seal pups on Heard Island in the sub-Antarctic with signs that suggest they were killed by a destructive bird flu, authorities said on Friday.

The virulent strain of H5N1 bird flu has spread through wild bird and mammal populations since 2021, killing millions, infecting poultry and dairy farms and even some farmworkers.

"At this stage it is not a confirmed detection," Australia's agriculture department said in a statement, adding that it would send samples from the dead seals to Australia for testing.

Since the virus has already been found on the nearby French Kerguelen and Crozet islands, symptoms consistent with H5 bird flu in wildlife on Heard Island was not unexpected, the ministry added.

Off the migration routes of big birds such as geese that spread infection, Australia is the only continent free of the highly contagious virus. But further spread through Antarctica could eventually raise the risk of infection from the south.

Heard Island would be the farthest the flu has reached in the Antarctic since arriving from South America in 2023.

Formed by a 2,745-m volcano that rears up from the sea more than 4,000 km southwest of Perth and 1,700 km north of Antarctica, it is a breeding ground for large populations of penguins, seals and seabirds.

Scientists of Australia's Antarctic Division who spent 10 days there found healthy animals until late in their trip when they encountered hundreds of dead elephant seal pups, said Julie McInnes, one of its ecologists.

"It was a significant proportion of the pups in that section (of beach)," said McInnes, who was on the trip. “It was unclear whether the virus will spread to other areas or species on the island and researchers will visit again around year-end,” she added.

The agriculture ministry said the confirmation of bird flu would not substantially increase the risk of its spread to Australia.

Australia has been bracing for the arrival of H5N1 bird flu, tightening biosecurity at farms, testing shore birds for disease, vaccinating vulnerable species and war-gaming response plans.