Boulogne-sur-Mer, France - In the dead of night, a French trawler cuts through the Channel's pitch-black waters on a hunt for cuttlefish that takes captain Pierre Lepretre and his crew across British lines.
For decades French fishermen have cast a wide net across the strait that acts as a natural border between Britain and France.
But as the clock ticks down to December 31, when Britain's divorce from the EU becomes complete, they fear that London's promise to "take back control" of its territorial waters could leave them high and dry.
For Lepretre, whose UK catch makes up 70-80 percent of his income, being barred from British fishing grounds would spell ruin.
"If we can no longer go to the English side we'll go bankrupt," the fisherman said as he counted his morning's catch: 90 kilos (200 pounds) of cuttlefish, 15 kilos of squid and 20 kilos each of red snapper and mackerel.
His boat is based in Boulogne-sur-Mer, about 40 minutes from the maritime border.
Grievances over fishing rights were one of the driving forces in the 2016 Brexit campaign, with British fishermen complaining of EU neighbours with more generous quotas plundering the country's stocks.
Within hours of Britain leaving the EU on January 31 this year, French fishermen found themselves barred from waters around the British Channel island of Guernsey -- a spat that lasted a week.
With Britain and the EU both playing hardball over the terms of a wider trade agreement, there are fears of further standoffs.
- Storm warnings -
In a leaked report last year, the British government anticipated that barring EU vessels could lead to "clashes between vessels", "violent disputes" or even the "blockading of ports".
To try and create goodwill, fishermen from Boulogne-sur-Mer have set up Whatsapp groups to liaise with their British counterparts on issues such as the location of British lobster pots that French trawlers should give a wide berth.
"It works well on the whole," Lepretre said.
Fisheries have been a flashpoint in trade talks between the EU and Britain, with chief EU negotiator Michel Barnier identifying it as one of the EU's top two priorities.
The EU wants any future deal with Britain to uphold the bloc's common fisheries policy, which shared out catch quotas based on 1970s trends.
Britain, which has vowed to become an "independent coastal state", has pushed for annual negotiations on quotas that would significantly increase Britain's share.
But in a sign that London might be prepared to soften its position, the Guardian newspaper reported last week that Britain had offered a three-year transition period for European fishing fleets.
- Dutch supertrawlers -
For Lepretre, as for many other fishermen in France where fish and seafood caught in British waters make up 30 percent of sales, the stakes are high.
His gleaming 19-metre (62-foot) trawler, which he ordered just two weeks before Britain voted to leave the EU, set him and his uncle back nearly a million euros ($1.17 million), most of it borrowed.
"If I had known, I would never have signed (the purchase order)," said the seaman, who comes from a family that has been fishing in the Channel for three generations.
He worries that if EU fishermen are frozen out of British waters they will all fall back on France "and there will be big problems cohabiting".
The French take a particularly dim view of Dutch supertrawlers that were grist to the mill of pro-Brexit groups such as Fishing for Leave.
In the event of a no-deal Brexit, Pierre's uncle Olivier Lepretre, director of the fishing committee of the northern Hauts-de-France region, believes there is only one solution.
France, Belgium, Spain and other coastal countries "should all take back control of their waters until new agreements are negotiated".
By Nicolas Gubert