“It’s a recording of an actual BBC broadcast,” said Dave Ornsby, the center’s operations officer. “Thirty-two ships from Grimsby sank in the ’50s.”

Apparently, none of this work or lifestyle appeals to British youths.

“You can’t get young people to fish these days,” said Danny Normandale, a skipper with three decades of experience. “If you say to them, ‘I’ll take you if you’re willing to learn,’ their next question is, ‘Do you have Wi-Fi on the boat? Do you have the internet?’”

Were the manpower problem solved, others would persist. The species in Britain’s waters are scallops, crab, lobsters and other delicacies that have never been popular in this country. The fish of choice here are cod and haddock, staples of fish-and-chip shops. Those species are found closer to Norway and Iceland.

[Read why some U.K. Lawmakers Believe Britain Should Consider Delaying Brexit]

In other words, Britain exports most of what it catches and imports most of what it eats. Either the country will need to change its appetite or it will need to trade.

Mr. Hancock, the former skipper, is undaunted. In the hallway of his office hangs a poster of a cod, clad in armor and clutching a Union Jack. Above it are the words “Fishing for Leave,” and below it “Save Britain’s Fish,” rallying cries during the Brexit campaign.