Bird flu has been detected in a seal and a gull on Macquarie Island, a remote outpost halfway between Tasmania and Antarctica.
Samples collected from a southern elephant seal and a kelp gull were returned with island personnel and subsequently tested, returning a positive result for H5 bird flu.
Tasmania's Minister for Environment and Climate Change Guy Barnett said in a statement on Thursday it was the "first recorded detection in a marine mammal in Tasmania".
Federal Agriculture Minister Julie Collins told parliament three other species had returned negative tests, including skuas, giant petrels and penguins.
She also said there had been no signs of any mass mortality events among the island's wildlife at this stage.
Ms Collins said the samples from the southern elephant seal and kelp gull would undergo further testing at a CSIRO laboratory.
The subantarctic island, 1,500 kilometres south-east of Hobart, is a World Heritage-listed wildlife sanctuary with up to 4 million seabirds and 100,000 seals.
In August, the ABC reported the Australian Antarctic Division planned to extract personnel from Macquarie Island in the Southern Ocean due to the psychological risk posed by a potential outbreak of bird flu.
It is feared up to 90 per cent of baby elephant seals could perish, as happened on Heard Island over summer, where more than 13,000 pups are believed to have died from bird flu.
As bird flu continues to be detected in Tasmania, members of the public are being encouraged to continue reporting sick or dead birds.
"Reports play an important role in helping authorities detect and respond to potential cases," Mr Barnett said.
Avoid contact with sick or dead birds and report sightings through the government's website or by calling the Emergency Animal Disease Hotline on 1800 675 888.
The Department of Natural Resources and Environment Tasmania provides regular public updates through media releases.
The latest testing and surveillance figures are updated on the department's website.