A controversial salmon farm near a world heritage site on Tasmania's east coast will continue to operate after a legal challenge against its approval was dismissed in the Federal Court.
Tassal's farm at Okehampton Bay, that can hold up to 800,000 fish, was in August given the environmental green light by the federal government.
But Environment Minister Josh Frydenberg's decision was challenged by the Bob Brown Foundation and tourism businesses of millionaire Graeme Wood that are developing in the area.
They argued the department had failed to consider the farm's impact on the world heritage value of a site at nearby Maria Island and calving endangered southern right whales.
On Thursday in Hobart, Justice Duncan Kerr dismissed the legal challenge.
He cited evidence that visual and noise impacts from the fish farm on the world heritage site were likely to be low and approval was made on a rational basis.
"It's a complex judgment. I think it's wrong. It's got mistakes at the heart of it," Mr Brown said outside court, flagging further legal action.
"The fact this ruling has gone against us is not a deterrent for us to try and protect the east coast.
"We will be considering this judgment and looking at the potential for an appeal."
Recreational fishers and conservationists campaigned against the farm but it was supported by Tasmanian government for its ability to create jobs.
Tassal chief executive officer Mark Ryan said the Federal Court decision would provide certainty for the company's east coast workers.
"The site has been scientifically researched and critiqued through careful assessments over a number of years," he said in a statement.
"Okehampton Bay continues to be a good site in terms of water temperature and environmental conditions.
"Tassal has extensive environmental monitoring in place on site, near the site and more than 15 kilometres away."
Tassal in 2017 said it would grow and harvest seaweed around the Okehampton Bay pens to reduce potentially damaging nitrogen levels in the water.