More than a dozen shellfish lorries parked near the UK prime minister's residence in Downing Street on Monday in protest over post-Brexit bureaucracy that has stopped them exporting their catch to the EU.
Lorries emblazoned with slogans such as "Brexit carnage" and "Incompetent government destroying shellfish industry" parked metres from Boris Johnson's central London office.
Last week, Scottish fishermen threated to dump tonnes of shellfish in central London over a collapse in the price of fish that has put some businesses at risk of bankruptcy.
The fishermen say they have not been able to export stocks to Europe since the start of the year after the introduction of catch certificates, health checks and customs declarations added lengthy delays to delivery, prompting European buyers to reject them.
"We strongly feel the system could potentially collapse," said Gary Hodgson, a director of Venture Seafoods, which exports live and processed crabs and lobsters to the EU and which has trucks parked at Downing Street.
"Prime Minister Boris Johnson needs to be honest with us, with himself and with the British public about the problems for the industry."
He said he had cancelled several lorries since December due to red tape involved with exporting to the EU. He said one operator needed 400 pages of export documentation last week to board a ferry to Europe.
Monday's protesters said the British government needed to understand the severity of the problems and the effects on coastal communities.
They want a more workable system and say there is a shortage of customs agents on both sides of the Channel.
"Many fishing communities did vote to leave but I don’t think anyone who did anticipated being constrained by documentation and restrictions that have now been thrust upon us," Mr Hodgson said.
"We need to bring the country together now and find workable solutions to limit the damage to the economy and to protect jobs."
The government’s food chief George Eustice told Parliament his staff had held meetings with Dutch, French and Irish officials to try to "iron out some of these teething problems".
Last week, Jamie McMillan of Scotland’s Loch Fyne Langoustines seafood company said: “The fishing industry has been made a fool of.
“If Scottish exporters can’t get their product to market next week, we will be at the gates of Westminster and we’ll be dumping our shellfish on your doorstep, rotten."