The federal government is under increasing pressure to rule on the future of salmon farming in a remote Tasmanian harbour, the only home of a fish at risk of extinction.
Fresh scientific advice from a government committee has recommended the salmon industry in Macquarie Harbour be scaled back or removed to protect the endangered Maugean skate.
It found the industry posed a "catastrophic risk" to the survival of the species.
There are only 40 to 120 adult skates left in the wild, with the population projected to drop by 25 per cent in the next generation, the committee estimated.
Environment Minister Tanya Plibersek in November launched a review of salmon farming in the harbour after conservation groups challenged 2012 approvals.
Earlier scientific advice provided to the government called for an urgent salmon destocking before last summer to help protect the skate.
"This is now the second time the (federal) government has been advised by the (committee) to make an extreme intervention to save the Maugean skate," Greens Senator Peter Whish-Wilson said.
"How many times do scientists need to raise the alarm before the minister acts?"
Salmon operations in the harbour began in the late 1980s and peaked at 20,000 tonnes in 2014/15 but have since been reduced.
The salmon industry, Tasmania's governing Liberals and the Labor opposition back aquaculture in the harbour, and have also called for a swift decision to end worker uncertainty.
Workers plan to visit Canberra next week to deliver their message to the Ms Plibersek personally.
A spokeswoman for the minister said she was required to assess all relevant information.
"People on all sides of this debate - including industry and environmentalists - would agree it’s important the reconsideration decision is legally sound and based on sound evidence," she said.
"The government is acting in accordance with the best advice, including legal and scientific advice."
Salmon Tasmania, which represents the state's biggest aquaculture companies, believes industry and the skate can co-exist in the harbour.
In July, the first skate from a captive-laid egg hatched as part of a breeding program in laboratories south of Hobart.
A $7.2 million trial to pump reoxygenated water from a barge into the harbour is underway.
Oxygen levels, a broad indication of the water's health, have shown recent signs of improvement but haven't returned to pre-2010 levels.
Salmon Tasmania chief executive Luke Martin noted the recent scientific report acknowledged a range of water quality impacts including climate change and currents.
"There are absolutely no guarantees that simply ending salmon aquaculture in the harbour will save the skate," he said.
"But it is 100 per cent certain reducing aquaculture ... will cost hundreds of jobs and devastate communities."
Anti-salmon community group Neighbours of Fish Farming said there was "no excuse" for further delays in removing aquaculture pens.
