Fish farmer Petuna Aquaculture will remove its much-prized Aquaculture Stewardship Council branding from products sourced from Macquarie Harbour because of low oxygen levels.
The move has led to calls from environment groups for a withdrawal of salmon farming from the west coast waterway.
An audit in November last year showed oxygen levels in the harbour were below the standard required for ASC certification, which recognises responsibly-farmed seafood.
Petuna said while dissolved oxygen levels had since returned to normal and conditions in the harbour were currently good, it would take some time to ensure those conditions were sustained.
Company chief Ruben Alvarez said it was critical to establish the long-term health of the environment before the company sought to restore its ASC certification.
"This is one of the recognised challenges of farming fish in Macquarie Harbour, which is subject to constant natural variations in the marine environment that bring low oxygen water to the surface," he said.
"It is important to emphasise that this is a naturally occurring event that has nothing to do with the way in which we operate our marine farms."
Petuna said ASC branding would be removed from any product that is not certified.
Five months ago, Tassal struck a deal with Petuna to share fish farming operations in Macquarie Harbour.
Tassal, the first aquaculture company to receive full ASC certification, is also considering withdrawing but said it was committed to sustainable farming in the harbour and that its leases were conservatively stocked.
'Review of fish farming in harbour needed'
But Philip Cocker from Environment Tasmania said the withdrawal from certification highlighted a need to review fish farming in Macquarie Harbour.
"We knew back in 2012 that low oxygen levels were going to be an issue and yet the overstocking went ahead with the EPA's approval," he said.
"I think we should take a lot more notice of the science.
"We should be decreasing the stocking levels or not stocking in Macquarie Harbour until we understand the impacts of what we're doing."
Mr Cocker said there was growing consumer concern about where food was grown and sourced.
"I think the community are taking a much more conscious effort to know where their food comes from.
"When they see a certification on their supermarket shelf or similar, they feel some confidence in that product."
Mr Cocker said evidence was growing that Macquarie Harbour might not be a suitable place for industrial salmon farming.
"What's been going on is not sustainable and we're deeply concerned that not only the maugean skate will go extinct but there will be long-term damage to the harbour."
An EPA (Environment Protection Authority) spokeswoman said it would review the information provided to the ASC by Petuna as part of the ongoing environmental management of salmon farming in Macquarie Harbour.
