BRIXHAM, England — In the pitch black of early morning, huge waves hurled the 30-ton vessel from side to side, drenching crewmen who struggled to keep their footing as they cast the trawler’s nets into the swirling seas.
But, once back on the bridge, the skipper, Dave Driver was oblivious to the stomach-churning motion of the boat, and dismissive of the perils of his work — even as he recalled once falling overboard and, on another occasion, rescuing two fishermen from drowning.
“I’m my own boss, I do what I want, I think it’s the best job in the world,” said Mr. Driver, who left school at age 15, but now owns the 1.2 million pound trawler Girl Debra, named after his wife.
He has only one major gripe in life: the French.
Mr. Driver thinks French boats are allowed to take too many fish too close to the British coast — touching on a deeply emotional issue on both sides of the channel that could dash hopes of a post-Brexit trade deal between Britain and the European Union.
Without the obligations of membership in the bloc, Britain wants to curb the number of continental trawlers in its waters. It is even scaling up its naval protection fleet in preparation for possible confrontations on the high seas.
Yet its fishermen rely on European markets where new trade barriers look certain. And if talks collapse many fear that France’s famously truculent fishermen could blockade ports to stop movements of British fish.
That matters in places like Brixham, in the southwest of England, because the British export most of the fish they catch and import the majority of what they eat.
About one third of the catch landed in Britain’s ports is mackerel, a species few Britons will touch. Overall, around four-fifths of the fish caught by British vessels goes abroad, mainly to other European countries.
Most of it is mackerel, herring and shellfish that fetch better prices abroad.
For decades this has been managed through a combination of free trade within the European Union and carefully drawn fishing rights based on historic fishing patterns. French and Dutch fishermen say they are hardly interlopers in Britain’s waters, as their ancestors worked there for centuries.
But Brexit has blown that system apart, and long-held resentments are coming to the surface.
The looming clash is in many ways extraordinary, considering how minute the fishing industry is in the greater scheme of things.
There are just 12,000 British fishermen operating 6,000 vessels and contributing less than one half of one percent of gross domestic product — less, according to one analysis, than Harrods, the upscale London department store.
“I can see a ridiculous amount of political emotion being spent on something that is not economically that important,” said Chris Davies, a former chairman of the European Parliament’s Fisheries Committee.
Yet a sense of injustice has festered for years in British coastal communities, many of which have little else going for them apart from fish.
The British governments once seemed happy enough to trade fishing for other concessions, downsizing the national fleet, said Mr. Davies, who added that many British fishermen sold their boats and fishing rights to continental competitors.
“There is a huge myth that some have created that they were robbed and it’s just not true,” Mr. Davies added, noting that much British fish is extracted by wealthy corporations rather than independent fishermen like Mr. Driver. Just 13 companies hold 60 percent of British fishing rights.
But gazing back at the English coastline from a few miles out at sea, things look different. If Mr. Driver had his way, foreign vessels would be barred from the first 12 miles of British waters, while British quotas would be expanded.
“The French have the majority of the fish, we just haven’t got enough quota,” said Mr. Driver, reading from a sheet of paper with his monthly cod entitlement.
“Thirty kilos — that isn’t even a box — that’s all I’m allowed, the French they fill up and, with all due respect,” asked Mr. Driver, pointing to the ocean, his voice rising a little, “what’s this piece of water called between England and France? It’s called the English Channel, not the French Channel.”
Around Britain’s coast, about 60 percent of the fish are caught by foreign boats, and one former British minister, Michael Forsyth, recently compared the situation to the British demanding two-thirds of France’s grape harvest.
In the English Channel zone — where Mr. Driver goes to sea — 84 percent of the cod is allocated to France and just 9 percent to the British, according to Barrie Deas, chief executive of the National Federation of Fishermen’s Organizations.
Yet, livelihoods are at stake on the other side of the Channel, too. Standing on the bridge of the Prins Bernhard, preparing to leave the Dutch port of Scheveningen on a 15-day voyage to Ireland’s west coast, Christophe Pauliac described being a captain not as a job, but “a passion.”
Mr. Pauliac’s father, grandfather and uncle were fishermen, and he is in charge of 30 French crew members on this floating fish factory, a large and sophisticated trawler that nets, then pumps up tons of mackerel and herring from the sea.
The fish are sorted and stored in a giant freezer that can accommodate more than 65,000 blocks of fish, each weighing more than 20 kilos, or about 45 pounds.
Excluding the Prins Bernhard from British waters — particularly those off the Scottish coast — would be a “catastrophe,” said Mr. Pauliac, who added that he competes not with smaller trawlers but with Scotland’s fleet of big, efficient, vessels.
Calm, polite and mild-mannered, Mr. Pauliac’s boat spends perhaps 70 percent of its time in British territorial waters. “There is room for everyone,” he said, adding that he hopes for an agreement.
Without a deal, there could be bankruptcies in France. Even crews that spend just 30 percent of their time in British waters would struggle, said Antoine Dhellemmes, director general of France Pelagique, the company that operates the Prins Bernhard.
The European Union wants to base new fishing quotas around Britain on existing ones, and make them of long duration, rather than haggling annually as the European Union does with Norway over fishing rights.
The British want the opposite. But one question is whether the British fishing industry will get the better deal it demands or whether history will repeat itself with London trading fish for finance — or another sector — in a broader trade deal.
There is danger for Britain’s fishing industry if the European Union imposes tariffs on imports. Even without such restrictions, British fish will need new food safety certification before export, and time-consuming checks are likely at continental ports.
Extra costs and delays could drive some merchants, processors and fishermen out of business.
Perhaps the best hope that a deal can be struck is the fact that British fishermen seem to be demanding less than some expected.
In the Cornish port of Newlyn, Andrew Pascoe, talking on the quay side next to his vessel, the Ajax, called for only modest increases in fish quotas and the exclusion of foreign vessels from a zone 12 miles off the British coast. In many areas there is now a six-mile limit for French boats.
“Some fishermen would say ban all foreign trawlers but we couldn’t claim everything back and catch all that fish,” said Mr. Pascoe, who is also chairman of the National Federation of Fishermen’s Organizations.
A truck from Portugal routinely meets one of Mr. Pascoe’s boats so that its haul of shellfish can be driven straight to the continent, illustrating the importance of European markets to him. His Portuguese customer has promised to keep the arrangement after Brexit, whatever the extra costs, he said.
But many are unsure that things will go so smoothly.
“We hold the access card and the Europeans hold the market card,” said Sam Lambourn, as he tinkered with the Lyonesse, a catamaran used for sardine fishing in the same port.
“The markets are interrelated and nobody is isolated,” he said, “and anyone who thinks they are not going to be affected is in for a surprise.”