Mark Eather marketed himself as the Sustainable Fisherman, supplying some of Australia's top chefs, including Neil Perry and Kylie Kwong.
But in the Supreme Court in Hobart the 58-year-old was convicted of trafficking in 605.95 kilograms of rock lobster between January and October 2011.
The crown's first attempt to convict him failed when the judge on the original trial in 2015 ordered the jury to return a not guilty verdict because under the legal definition of "trafficking" it appeared at least two people had to be involved.
The crown successfully appealed that and Eather this week pleaded guilty to the charge.
"Five and a half years of my life, half a million dollars - for what? The fact that I had possession of lobsters that weren't tagged," Eather said outside the court after his conviction.
Chief Justice Alan Blow accepted there was no suggestion Eather had bought the seafood on the black market.
But he did not have the necessary licence to deal with the untagged seafood.
Chief Justice Blow fined Eather $7,700 for the trafficking but the conviction comes with special penalties under the act of $169,666.
The court heard the mandatory demerit points that went with a conviction meant he would not be able to hold a fishing licence in Tasmania again.
"It does affect the business but those who know me know the circumstances there - the reason I've done that is I've been through five and a half years of this process," he said.
Eather admitted paying the fine would be difficult.
"Of course it's going to be difficult but this whole debacle has cost me more than half a million dollars, a lot of which I've borrowed and we'll have to be repaying," he said.
The court heard Eather had a number of previous fisheries convictions dating back to the early 1990s.
"My business will continue because I've got fishermen who work for me all over the country but whether I do any more business in Tasmania ... I mean it's just ridiculous," he said.
"I'm a very passionate sustainable and ethical fisherman and I'm quite vocal about that, the practices that are enabled in this state are atrocious - they don't like me talking about that, I won't stop that."
