BOSTON – A shutdown of the monkfish fishery that blindsided many fishermen and threatened the Northeast industry ended when federal regulators reopened the fishing grounds last week.

The National Marine Fisheries Service, which manages New England waters, adopted new regulations that allow monkfishing, though 16 days later than fishermen expected.

Many fishermen thought a planned May 1 closure had been averted last year when a rare joint research project with federal scientists showed healthier stocks than first believed.

But proposed regulations to keep fishing grounds open weren’t enacted by May 1, and the fishery closed.

Bill McCann, a fisherman from Wareham, said he spent the last two weeks agonizing over how he was going to pay off the $300,000 he invested in a new boat. On Friday, he was preparing to go to sea.

“It’s total relief,” McCann said. “It just saved me from going bankrupt. It’s that critical.”

The new rules change the trip limit to 450 pounds to 550 pounds of tail weight, depending on the fishing permit category, significantly less than last year’s 1,000 pound to 1,500 limit. And the days missed are some of the best in the prime fishing time known as the “spring run,” when monkfish move into shallower waters.

Monkfish processor Dave Pelletier of A&A Seafood in New Bedford figures he lost about $50,000 in the delay, but said at least now he can do business. He said he’d been paying some workers to do odd jobs around his house, just to keep them from quitting before the situation was resolved.

“At least they’re going to be able to work, they’re going to be able to survive,” he said.

Chris Zeman of Oceana, an environmental group that filed an objection to the new rule in April, said the new research still shows a depleted stock, and boosts numbers by including areas that have not traditionally been fished.

“It appears NMFS is going to continue to allow overfishing,” Zeman said. “This action has no compromise for conservation.”

Fisheries service spokeswoman Teri Frady said the new research gives the best numbers yet that monkfish will continue to rebuild under the current plan.

“It was not geared to get a particular result,” she said.

Monkfish were considered a junk fish in the 1970s, but a market developed for their livers and tails – said to taste like lobster – after other stocks declined.

Now, monkfish are sought by fishermen from Maine to North Carolina. The fishery’s revenues of $52.7 million were fifth highest of any species in the Northeast in 2000, the most recent year statistics are available.

In October 1999, federal regulators adopted a four-year plan to close down the fishery by May 2002 after concluding monkfish were being dangerously overfished.

Fishermen, boat owners and processors banded together to dispute the numbers. After a $520,000 joint study, federal scientists agreed they might have a case. The proposed rule was recommended in January, but approval did not come quickly.

Frady said the raft of lawsuits against the agency – 104 pending at last count – mean it has to move more deliberately. A federal judge recently imposed new fishing rules after the agency lost a suit accusing it of failing to protect fish stocks.

U.S. Sens. Susan Collins and Olympia Snowe, both Maine Republicans, praised the agency’s decision.

“This fishery should never have been closed in the first place,” Snowe said. “Ultimately, sound science has proven something fishermen have known: that the monkfish fishery is in recovery, and reasonable fishing limits are in order.”

George Walsh, a Newport, R.I. fisherman, said he’s happy to be back to work, but the delayed opening left a bad taste in his mouth.

“It was just inappropriate, and it was unfair,” Walsh said. “It totally erodes a sense of trust – the trust that’s necessary for industry and fishery scientists to work together to get the most accurate science.”