The salmon farm hit by a massive jellyfish attack last week has confirmed its only remaining site has now been wiped out as well.
John Russell, managing director of the Northern Salmon Company, said the juvenile fish that were growing to maturity at Red Bay on the Co Antrim coast were all destroyed in the last couple of days by a second jellyfish attack.
Further huge jellyfish swarms have now been reported off the coast of Scotland, according to the Marine Conservation Society.
The latest attack means that Northern Ireland's only salmon farm cannot now rely on restoring its business from next autumn when the young fish would have begun to reach maturity and it has renewed its appeal for Government assistance.
"We have another farm of juvenile stock which have all been wiped out in the past two days. This is a major blow for us," said Mr Russell.
He said workers are still continuing with the mammoth task of clearing away the hundreds of thousands of dead fish for incineration and the board is to meet shortly to consider its options.
Mr Russell said he was hoping to come to some sort of arrangement with the Government that would allow the fishery to return to producing its high-value organic salmon.
However, he said he is not getting very " positive sounds" from the Government at present, after Fisheries Minister Michelle Gildernew warned she had no funds available to help within her department's budget.
The minister is now due to speak to her Executive colleagues to see whether some solution can be found.
The office of First Minister Ian Paisley, who is MP for North Antrim, last night confirmed it has been in touch with Downing Street about the disaster.
Mr Russell said there have been precedents set in Scotland for small businesses hit by similar crises and he said Mr Paisley has been working hard to try to find help.
"There's pressure coming from a lot of our customers corresponding with them, and just asking them to help," he said.
"This is a fantastic product from Northern Ireland and the province can't afford to lose it."
He said he has also written to some of the leading chefs who have championed the brand, appealing for them to make the case for a rescue package.
" We've had a huge global response and fantastic support, which we're most appreciative of. Hopefully, it can help us through," he said.