Salmon deaths at 'eye-watering' levels in Macquarie Harbour
Almost 2,000 tonnes of farmed salmon died over a 15-month period in Macquarie Harbour on Tasmania's west coast, new data shows.
The Environment Protection Authority's (EPA) mortality data was obtained by conservation group Environment Tasmania, which submitted the Right to Information (RTI) request in December last year.
But it took until this week for the information to be made public after salmon companies sought reviews of the EPA's decision to release the data, as they are entitled to do under RTI laws.
The EPA regulates 10 salmon leases in the harbour. (Supplied: Tassal)
The data shows a total of 1,907 tonnes of farmed salmon died in the harbour between October 2024 and December 2025.
"Salmon has no place in Macquarie Harbour," Environment Tasmania campaigner Jess Coughlan said.
"These mortality rates are eye-watering, remembering these figures are from a year without a super El Niño."
Industry disputes death figures
Industry group Salmon Tasmania said up to 9,500 tonnes of salmon can be farmed in the harbour each year under a feed cap.
The mortality data was obtained by Environment Tasmania. (Supplied: Tassal)
Environment Tasmania said this would infer about 15 per cent of the total maximum haul died over the 15-month period.
But Salmon Tasmania chief executive John Whittington said the maximum tonnage could not be used to determine a "mortality rate".
"Mortality is measured by counting the number of fish that died, not their weight," Dr Whittington said.
"Of all the fish held in Macquarie Harbour at any time between October 2024 and December 2025, fewer than 8 per cent died during that period."
The new figures come after a separate RTI in late 2024 showed a total of 1,149 tonnes of salmon had died over a seven-month period between September 2023 and March 2024.
Monthly data on salmon deaths doesn't show locations
Since 2025, the EPA has released monthly data showing the total tonnage of mortality among salmon farms across the state, but it is not broken down by location.
Macquarie Harbour, which is the only habitat for the endangered Maugean skate, makes up only a small portion of the salmon industry's annual production across Tasmania.
Dr Whittington said mortality was "unfortunately part of all livestock farming".
He said there was no standard "mortality rate" for farmed salmon.
Salmon Tasmania CEO John Whittington said mortality was measured by numbers of fish not weight. (ABC News: Madeleine Rojahn)
"As with other forms of farming, survival rates or losses vary by year, location and season," Dr Whittington said.
"Salmon growers employ a range of strategies to maintain fish health and maximise survivability, including selective breeding, vaccination, specialised diets and growing fish larger on land so they spend less time at sea."
The new RTI data did not include details about what caused the deaths of the salmon.
Salmon Tasmania said Macquarie Harbour was free of the bacterial disease that had caused other mass mortalities. (ABC News: Sophie Zoellner)
But Dr Whittington said Macquarie Harbour was free of the bacterial disease that had caused mass mortality in salmon pens in other parts of the state.
"There are a range of causes of salmon mortalities however P. salmonis is not present in Macquarie Harbour,"
he said.
As such, he said the industry had not applied to use the antibiotic florfenicol in Macquarie Harbour.
Ms Coughlan said there had been "near complete opacity surrounding operations where disease and mortality are concerned" in the harbour.
Environmental licences expired
The EPA regulates salmon farming at 10 leases within Macquarie Harbour.
However, the environmental licences issued to the three salmon companies that operate there expired almost a year ago.
A map showing the location of salmon farm licences in Macquarie Harbour. (ABC News: Magie Khameneh)
Prior to the expiration, the companies applied for new licences, meaning they can continue to operate pending the outcome of their applications.
The EPA told the ABC it was continuing to assess the environmental conditions in Macquarie Harbour to inform future regulatory decisions about salmon farming in the region.
Three companies farm salmon in Macquarie Harbour. (ABC News: Sophie Zoellner)
"The timing of a decision on the environmental licence renewals will be determined by the completion of the necessary assessment and scientific work.
"All environmental licences remain in force as per the legislation."
'Critical habitat' consideration
Tasmania's environment department is currently considering declaring the harbour a "critical habitat" for the Maugean skate.
It comes after the state's Scientific Advisory Committee found there were multiple intersecting threats to the Maugean skate, "including declining dissolved oxygen, aquaculture impacts and climate influences that pose a high risk."
The endangered Maugean skate species is believed to exist only in Macquarie Harbour. (Supplied: Jane Ruckert)
Earlier this year, the EPA issued a directive for salmon companies to supplement dissolved oxygen into the harbour to offset the daily drawdown of oxygen by salmon farms.
It said the industry had now reached a total oxygenation rate of 10.3 tonnes per day, which was the required level.
"The EPA will continue to closely monitor dissolved oxygen conditions in Macquarie Harbour and publish water quality data every six months."
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