The Scottish fishing fleet is facing a days-at-sea crisis that could leave scores of boats stuck in port and put as many as 5,000 shore jobs at risk.
Processors fear they will have to close factories and lay off workers if trawlers stop working and supplies dry up.
White-fish vessels have used their catching-time allocations for this year far more quickly than expected – and may have to languish in harbours for up to five weeks in the summer.
Merchants say this would cripple their industry and devastate fishing communities around the country.
They have called for emergency talks with the Scottish Government.
Will Clark, of the Peterhead and Fraserburgh Fish Processors’ Association, which represents about 30 firms, said he had been told fishing effort had to be cut by 25%.
He said last night: “We were asked by the producers how we felt about a four-to-five-week shutdown, possibly in July.
“There is absolutely no way we would be able to absorb that.
“This is not scaremongering and we have asked Fisheries Secretary Richard Lochhead for a crisis meeting to discuss the situation.”
Andrew Charles, who runs Aberdeen seafood firm J. Charles, warned that up to 60% of processors would go out of business if they were starved of supplies for five weeks.
He blamed the UK Government for a “total failure to secure the future of fishing” in the face of tougher European Commission conservation rules, and said processors needed support to allow them to quit the industry “with dignity”.
Mr Charles added: “It is very sad but the sector is going to have to reposition itself on a smaller scale.”
Fish producers have warned that, without a shutdown in the near future, there will be no days at sea left for the fleet by the second week of November.
Trawlermen warned their livelihoods were already “hanging by a thread”.
Peterhead skipper Peter Bruce, 48, said it was “unthinkable” that the white-fish fleet would be asked to tie up.
“If our boats don’t go to sea, our men don’t get paid,” he said.
“Fishermen are bending over backwards, always doing what they are asked, but there never seems to be an improvement in the deal we get from Brussels.
“We realise we have to conserve the stocks but in my opinion the Scottish fleet is doing more to adhere to this than the rest of Europe.”
Scallop fishermen John MacAlister, 56, chairman of Mallaig and North West Fishermen’s Association, said the impact of a white-fish shutdown would be felt widely.
“The whole industry seems to be hanging by a thread just now, what with the price of oil, operating costs and stricter regulations,” he said.
Association secretary John Hermse said prawn boats could also be forced to tie up.
“This is a massive problem – the worst I’ve seen in 30 years,” he said.
Jonathan McAllister, skipper of Oban-based prawn trawler Freedom, said it was unlikely west coast prawn fishers would run out of days.
However, he feared a shutdown would drive north-east white-fish boats to the west coast to go after prawns instead.
Mr McAllister warned: “Our fishing grounds wouldn’t stand the pressure.”
Angus Macleod, skipper of the Gairloch-based prawn trawler Enterprise, said: “We manage to operate a boat in the days we are given, so why can’t they on the east coast? They want to work 365 days a year.
“My concern is that, if there is a five-week ban on fishing in the North Sea, they will all come over to the west coast.”
Scottish Fishermen’s Federation chief executive Bertie Armstrong admitted the industry had “simply got it wrong” over days-at-sea allocations.
“This is a really difficult and serious problem and will require careful thought by industry and government as to what the best way forward is.
“It is work in progress, but we are facing stark choices.”
Scottish Fishermen’s Organisation quota manager Jane Sandell said: “Everything is up in the air at the moment and various ideas are flying around.
“It is up to the government and industry to decide what to do.”
Scottish White Fish Producers’ Association executive chairman Mike Park, however, insisted a shutdown would not happen.
He said skippers were willing to increase cod conservation measures to head off the move and claw back extra days they would gain as reward.
“We should be OK,” Mr Park said.
“The Scottish Government and industry are working hand-in-hand to make sure that we have a full 12-month fishery. We will resolve this problem.”
A Scottish Government spokesman said: “The EU’s days-at-sea system is staggeringly complicated – a prime example of why fisheries management cannot be dictated from Brussels and should be returned to Scottish control.”