About one in 10 farmed salmon in Macquarie Harbor died over a seven-month period, documents show

Environmentalists have raised concerns after new data showed around 10 per cent of salmon farmed in Tasmania’s Macquarie Harbor died in the process.

About 9,500 tonnes of salmon were expected to be produced at the port on the state’s west coast this year, according to Salmon Tasmania’s website.

Environmental group Neighbors of Fish Farming (NOFF) has filed a Right to Information request to find out the mortality rate.

In response, the Ministry of Natural Resources and Environment released data showing that 1,149 tonnes of salmon died between September last year and March this year.

The month of January recorded the highest percentage of deaths, with 313 tons of dead salmon.

“This is an industry that claims this is the best practice in the world, that animal welfare is the highest priority and that it is an industry that is fit for purpose,” said NOFF chairman Peter George.

“Well, it’s clearly not.

The information released was limited to weight statistics and did not include the number of fish that had died nor the reasons for their deaths.

Mr George said more transparency was needed.

“This is happening in public waters,” he said.

Reporting on mortality including fish numbers

The three aquaculture farms operating in Macquarie Harbor – Huon, Petuna and Tassal – are required to report all cases of increased mortality to the state’s chief veterinary officer and the Environment Protection Authority (EPA).

Such events occur when disease or mortality affects more than 0.25 percent of fish in an individual cage per day for three consecutive days.

Last summer, 66 cases of increased mortality were reported across the state, according to evidence provided at a budget estimates hearing last month.

The national data on mortality events does not include a breakdown of weight or number of salmon that died.

However, EPA chief Wes Ford told the hearing that such information would be available soon.

“We are in the process of implementing the new environmental permit conditions that will require companies to report grades or weights depending on the circumstances,” Ford said last month.

Salmon Tasmania CEO Luke Martin said the industry was the most regulated in the world and had done everything it could to reduce mortality.

“The industry’s goal is for the lowest possible number of deaths for obvious reasons,” Martin said.

‘No farmer wants to lose his cattle in large numbers.

“But the reality is that it is just a fact of life for all farmers, and it is no different for salmon farmers.”

He said there is no standard mortality rate and that a range of issues could be contributing to deaths, including warmer waters, jellyfish attacks and pesticides.

“And the percentage increases significantly from one year to the next, and also from one part of the state to another.”

A Tasmanian government spokesperson said the sector was subject to a “comprehensive biosecurity program” that included routine reporting requirements and the disclosure of mortality notifications.

The pressure on Plibersek to take action is increasing

A group of 34 scientists have written to federal Environment Minister Tanya Plibersek, urging her to withdraw environmental approvals for Macquarie Harbor salmon farms and ‘reposition’ the local community as part of a transition away from its dependency of the industry.

Ms Plibersek is currently considering whether to revise the 2012 approval for farm expansion.

Macquarie Harbor is the last known habitat of the endangered Maugean ray.

The ray is dependent on dissolved oxygen, and conservation advice to Ms Plibersek last year identified the salmon industry as “the main anthropogenic contributor” to oxygen levels in the harbour.

Salmon farms, state MPs and local councilors have increasingly questioned scientific research into the impact of salmon farms on the Maugean ray and the extent of the species’ decline.

Former director of the University of Tasmania’s Center for Marine Socioecology (UTAS), retired Professor Stewart Frusher, was among the signatories of the letter.

He said he was concerned that science was increasingly being “misrepresented” in attempts to pressure Ms Plibersek.

“Ministers told them they were going to take the science and so now they’re coming back and saying, ‘Oh, quick, we’ve got to do something and question the science,’” Mr Frusher said.

The industry is helping to fund an oxygen trial at the port, which the state government says has shown initial “promising results”.

The letter was also signed by five fellows of the Australian Academy of Science, including marine biologists and aquaculture researchers.

This week, Mr Martin questioned why scientists were not investigating Bathurst Harbour, where the ray was once known to live.

Mr Frusher said the ray had not been found in the deeper Bathurst Channel, while the rest of Bathurst Harbor was too shallow to be viable, mainly due to increased climate variability.

‘And because the waters there are so shallow, that may have caused them to become extinct.

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“It’s unlikely this is a place to release them.”

Last month, Labor MP Janie Finlay shared an opinion piece saying that while it would be “unfortunate” if the skate became extinct, they “wouldn’t lose any sleep over it”.

This post was “liked” by Labor leader Dean Winter.

Salmon industry-funded research by UTAS conservation ecologist Barry Brook assessed projections of ray population declines over the coming decades.

He wrote to Ms Plibersek that more work needed to be done on the projections, which may have been exaggerated.

Mr Frisher said this research did not dispute that there had been a significant drop in numbers.

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