More West Coast salmon grief

ENVIRONMENT Tasmania says Macquarie Harbour is still subject to low oxygen levels that caused the withdrawal of Petuna Aquaculture from a certification process.

ET director Philip Cocker said the results from the ASC certification process highlighted problems with the harbour.

“The latest ASC audit of Petuna leases found significant non-compliance with oxygen levels being below 70 per cent dissolved oxygen at several leases on multiple occasions,” he said. “Petuna has withdrawn from certification for its Macquarie Harbour leases as the findings of the compliance audits clearly show accreditation was not going to be granted.”

In May, the Environment Protection Authority reduced harbour stock levels to 9500 tonnes, down from 21,500 tones set in 2016.

Petuna chief executive Ruben Alvarez said Petuna had withdrawn from certification after an audit in November last year showed oxygen levels below requirements.

He said dissolved oxygen levels had since returned to normal and conditions in the harbour were good, but it would take time to ensure those conditions were sustained.

“It is critical to establish the long-term health of the marine environment before the company will seek to fully restore its ASC certification,” he said.

“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.

“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.”

The audit revealed a recent escape of 44,800 fish.