A flotilla of at least 60 boats has circled Huon Aquaculture's fish pens in Norfolk Bay and called for salmon farming to be permanently banned from the area.
Protestors took to the sea on a variety of craft, from large fishing vessels to single-person sailboats.
Many of the boats carried banners calling for Huon Aquaculture's licence to farm fish in the bay to be permanently revoked.
"We need assurances from the State Government and we need assurances from the salmon industry there will be no salmon farming for Norfolk Bay," said chair of South East Marine Protection Mark Duncan.
But Deputy Premier Jeremy Rockliff said the government was a strong supporter of the industry and had already implemented tough regulation.
"We have a salmon industry plan that we launched toward the end of last year that clearly states where salmon can be grown and not grown," he said.
"It gives the industry certainty. It gives the community certainty."
Huon Aquaculture was granted approval to stock diseased fish in the bay until the end of December.
Yesterday it announced it was moving the fish out a month early, saying recent tests were negative for pilchard orthomyxovirus, a disease that killed 1.3 million fish in Macquarie Harbour earlier this year.
"Will they be back again next year?" said Debbie Dunn, from the Tasman Peninsula Marine Protection group.
"Or in a few months? Or next week? We don't know.
"We'll do whatever it takes within the confines of the law. We'll keep going. We're not giving up."
Organisers of today's protest expected around 200 vessels to take part.
Mr Duncan said he didn't think Huon Aquaculture's plans for an early departure were responsible for the smaller turnout.
"No, not at all. It's the adverse weather," he said.
"They're pretty trying conditions so [we're] a little bit disappointed but [it's] a fantastic turn out."
After circling the salmon pens, protestors headed to Primrose Sands for a media conference.
