PEABODY, Mass. – Fishermen will find the number of days they can fish reduced as much as 24 percent, but they can lease days from other boats as part of a plan regulators adopted Thursday to govern the ancient industry through perhaps its toughest times.

The New England Fishery Management Council gave initial approval to the measures near the end of three grueling days of meetings. The action is aimed at satisfying a court order to enact tough new rules to stop overfishing.

A final vote on the rules, called Amendment 13, was expected late Thursday night.

Months of research and debate preceded the Thursday decision, but Chatham hook fisherman Paul Parker said it was impossible to know now what it all meant.

“Everybody involved here is just in shock,” he said. “There’s so many unanswered questions here tonight.”

The question of leasing unused fishing days, adopted by the council Wednesday, proved particularly contentious because of fears large boat owners would benefit disproportionately.

Leasing puts otherwise dormant fishing days to use, so regulators are forced to cut the total allotment of fishing days to protect fish stocks. Small boat fishermen say they can’t take any more reductions and couldn’t afford to lease days.

But others said they need to lease extra days to survive the cuts.

Daylong negotiations Thursday ended with a compromise offered by the Gloucester-based Northeast Seafood Coalition that cut six more fishing days for all boats, but permitted the leasing to go ahead with restrictions.

For instance, larger vessels are restricted to leasing from boats of the same size, preventing them from soaking up days of smaller boats.

Robert Lane, a New Bedford fisherman, said the plan makes it hard for big boats to find days to lease, but some sort of leasing had to be approved.

“I’m happy we at least got a start here,” he said. “If we’re going to be cut in half, you’ve got to find some way to make it.”

The council decisions were based on a proposal made Wednesday by the Northeast Seafood Coalition. It created a class of fishing days, called “B Days,” on which only healthy stocks such as haddock can be targeted. Fishermen can target any stock on “A Days.”

Thursday’s leasing compromise also spelled out the A and B day distribution to curb the heavier amount of fishing leasing will create. Under the distribution, for instance, a fisherman with the maximum of 70 days this year will have 53 next year, a 24 percent cut. He’d get about 11 “B Days.”

Proponents said “B Days” give fishermen a chance to keep their days and make money while protecting troubled stocks, such as cod.

But Maine fishermen say it holds little benefit for them because healthier fish are found off the coast of southern New England, where they don’t fish.

Thursday’s meeting began with a failed attempt by council member John Williamson of Maine to overturn the council approval of the Northeast Seafood Coalition plan.

The council is an advisory body to the National Marine Fisheries Service, which ultimately must approve the new slate of rules. The rules, set to go into effect next May, were ordered by a federal judge in December 2001 after she ruled the government wasn’t doing enough to stop overfishing.

On Thursday, the council passed other provisions of Amendment 13, including new gear restrictions and the opening of previously closed fishing areas to catch certain healthy stocks.

Strict catch quotas, which stop fishing when a certain number of protected fish have been caught, had yet to be discussed for New England waters on Thursday evening, despite the insistence of environmental groups that they were crucial to any plan.

Geoff Smith of the environmental group The Ocean Conservancy said he wasn’t confident the council would take the hard steps needed to stop overfishing by the meeting’s end.

“I’m really concerned the council is not going to pass a plan that meets the requirements of the law,” he said. “If they don’t, we’ll go to [federal regulators] to make sure they do.”