Mysterious chunks that washed up on a southern Tasmanian beach are continuing to be tested, with preliminary investigations suggesting they are fish oil deposits from nearby salmon farms experiencing mass mortalities.
The chunks were discovered at Verona Sands Beach in the Huon Valley, close to salmon farming operations currently dealing with significant fish deaths.
Darrell Cox, Director of Finfish Compliance at the Environment Protection Authority (EPA), said the chunks were “not rotting putrid fish flesh” as environmental groups had suggested.
“Those fish, when they die, they need to be retrieved from the water and taken for appropriate management on a land-based facility,” Cox told ABC Radio.
“When you’ve got a lot to get out of the water they can start to decompose and we understand that oil can be liberated from the fish and that oil will tend to float.”
“And the thing about these oils is they can be liquid as they warm up but they’ll tend to congeal at a cooler temperature, so we suspect something like that has happened.”
While Cox said he was not aware of the substance posing any health risks to dogs or swimmers, additional tests are being undertaken to check for the presence of diseases or antibiotics in the oil.
However, he noted that antibiotic contamination was “unlikely”, given the timing.
“The fish had only just begun to be treated with the antibiotic in the days immediately prior,” he said, adding the decomposing fish releasing the oils would likely have died before medication was administered.
The current mortality event has been attributed to multiple factors, including the Tasmanian rickettsia-like organism disease, warmer water temperatures and jellyfish presence.
Cox declined to specify exact numbers, but confirmed the deaths span multiple pens across several farms.
“Less than 1% of the fish have died, but nonetheless you’re talking about a large number of fish in multiple pens at different farms,” he said.
The Greens’ Vica Bayley and Senator Nick McKim said the EPA must be “fully transparent with Tasmanians about the scale of the fish deaths”.
The party wants to know how the deaths are being dealt with and the implications for the public and environment.
