By daybreak, much of the town of Gloucester, Massachusetts, US, has already been at work for hours.

Fishermen have long since cast off aboard boats named for their sweethearts and chugged out to sea before sunrise.

Clad in yellow and orange rubber suits, these seafarers drag giant nets across the ocean floor during 12-hour work days, hauling back the fish they will later bring to market.

For some 400 years, fishing has sustained communities such as Gloucester along America’s northeastern shores, where thousands of seafood processors, wholesalers, distributors and retailers make a living off the waterfront.

“It’s kind of the bread-and-butter and the backbone of the community,” said Dennis Robillard, who has scooped up fish off the coast of Massachusetts for more than two decades.

Now the federal government is contemplating what for generations seemed inconceivable — restricting or shutting down most of the cod fishing in the Gulf of Maine, a region that extends from Cape Cod up through Nova Scotia.

A recent government survey found that Gulf of Maine cod, considered a top earner for fishermen in the region, are in far lower numbers than what experts had thought.

Just three years earlier, the government had projected the area was well on its way to recovery after decades of overfishing. Since then, federal regulators have raised cod catch rates to nearly five times the sustainable level based on what are now reported as overly optimistic and incomplete estimates.

The new data now suggests the stocks are so depleted that even if the fishing industry were to shut down, codfish would still not recover by 2014 to the levels mandated by federal law. Beginning in May, that will trigger a legal requirement that fishermen bring in around 22% less cod than they caught last year. But next year is the big one — Gulf of Maine cod fishing could face more than an 80% reduction from prior years’ catches.

“This is total Armageddon now for the fishery,” said Vito Giacalone, a third-generation Gloucester fisherman and policy director for the Northeast Seafood Coalition, an advocacy group for the fishing industry. The coming restrictions, he and others say, are based on assumptions that come from data that’s “inherently volatile.”

“What happens when you do everything right and they still shut you down?”

Cod also swim alongside other fish, which means the proposed reductions would impact other industry staples such as flounder and haddock, even though those populations are considered to be far healthier.

While larger trawlers capable of traveling to more distant fishing grounds are expected to survive, the reductions could cost most of the region’s smaller crews their jobs.

“We basically have a balloon payment now to make up for those years (of overfishing),” said Steven Cadrin, a scientist at the University of Massachusetts-Dartmouth, who worked on the assessment.

Cadrin and others say a year isn’t enough time to make up the difference and meet federal mandates, which he says could signal an end to much of the region’s small-boat fleet.

Environmentalists say depleted stocks show the region needs time to recover.

“The coastal fishermen are facing an impossible situation through no fault of their own,” said Peter Shelley, a lawyer with the Boston-based Conservation Law Foundation, an environmental advocacy group.

“But once those fisheries are gone, that’s it.”

2012 Cable News Network. Turner Broadcasting System, Inc.