‘This could kill us’, salmon company Petuna warns Plibersek on Macquarie Harbour pen ban

One of Australia’s biggest salmon producers warns it may not survive if the Albanese government curtails fish farming in Tasmania’s Macquarie Harbour.

Salmon farmers Depha Miedecke and Tom Mountney warn they could go bust if evicted from Macquarie Harbour. Picture: Peter Mathew

One of Australia’s big salmon producers warns it may not survive if the Albanese government follows through on threats to curtail fish farming in Tasmania’s Macquarie Harbour.

Environment Minister Tanya Plibersek is reviewing the 2012 federal approval for salmon pens in the remote western harbour and has flagged the need for “lower salmon farming industry loads”.

The rethink is a response to concerns from scientists and conservationists that waste and oxygen depletion linked to the fish farms is driving the endangered Maugean skate, found nowhere else on earth, to extinction.

Farmed Atlantic salmon and ocean trout in Macquarie Harbour makes up about 13 per cent of total production for the $1.46bn homegrown industry. However, for ­Petuna Group, the stakes are much higher, with the company – one of three in the industry – relying on the harbour for half of its total production.

Petuna general manager (technical and strategy) Depha Miedecke told The Weekend Australian it was not an overstatement to say curtailment of fish farming in the harbour could threaten the survival of her company, which employs more than 160 Tasmanians.

“It would be catastrophic – it’s 50 per cent of our production,” Ms Miedecke said. “We’ve been operating here as an industry for nearly 40 years and we want to be here well into the future.”

Adam ‘Salty’ Saltmarsh, a salmon industry worker, in Strahan on Tasmania’s west coast, with his wife Samantha and children Logan, 12, Hudson., 9, and Paisley, 4. Picture: Peter Mathew

The federal government’s Threatened Species Scientific Committee has used the same term – “catastrophic” – to describe the industry’s impact on the skate.

However, Ms Miedecke challenged that view, arguing the species – estimated to have lost half its population between 2014 and 2021 – faced a multitude of threats, including hydro-electricity inflows, historic mining pollution, gillnet fishing, predators, and siltation of the harbour mouth.

“It’s a really complex water system … and what we do in terms of the nutrients and the impact on oxygen levels is a small percentage of the overall oxygen drawdown,” Ms Miedecke said.

“Yes, our industry is part of that, but we have taken action to mitigate that. Our biomass levels have reduced. We’ve had our environment licences renewed for a further two years, which shows the Environment Protection Authority has confidence in our operations in the harbour. And we’re looking at what other avenues we can do to improve oxygen levels.”

However, conservationists and scientists say the evidence is in: fish farms have caused the loss of half the rare, ancient species and must be evicted from the harbour.

“Its decline is strongly correlated with the aquaculture industry, so while the skate may have been able to endure all those other impacts, it certainly hasn’t been able to endure the salmon farming,” said Stewart Frusher, retired professor of marine science at the University of Tasmania.

“You’ve created a situation that unfortunately can only be rectified by getting rid of that industry out of that harbour.”

That prospect is horrifying to many in the town of Strahan, a hub for the aquaculture and tourism industries based around the harbour. “It would destroy Strahan fully,” said Adam Saltmarsh, who moved to the town 20 years ago and has worked his way from fish farm hand to maintenance manager at Tassal Group.

“I’m just one of many who have kids in the local school, use the local shops, or who have partners working locally. We’d all have to pack up and go.”

Ms Plibersek said the gov­ernment was “carefully considering the information and the scientific advice that it has obtained to ensure a proper, legally robust decision”.