WASHINGTON – When the Maine Marine Patrol discovered thousands of pounds of baby haddock mixed into the massive herring catch on two fishing vessels last month, it inflamed an already heated battle between New England groundfishermen and the herring trawler industry.

But the fish story delivered both good news and bad news for the fishermen and the federal authorities who regulate them.

The good news: The abundance of young haddock could be more evidence of a long-sought resurgence of the once overfished stock.

The bad news: Herring trawlers may face fines for taking young fish they say they can’t seem to avoid. And the hook fishermen who make their living on haddock are demanding retribution against the trawlers that wrongly hauled more haddock out of the ocean in the blink of an eye than they can catch legally in a long trip.

Caught in the middle are federal authorities who must decide whether the violations should trigger new restrictions on where and how the herring fleet can snag its catch.

“We haven’t seen this many haddock in years,” said Andy Cohen, who heads NOAA Fisheries’ northeast law enforcement office. “This is not a law enforcement issue. This is a fisheries management issue that needs to be grappled with. And we wouldn’t have this issue if we were not being successful in haddock rebuilding.”

The New England Fisheries Management Council will meet later this month to discuss the matter. And pressure is building from environmentalists and groundfishermen to draft regulations restricting the herring fleet and ban it from certain areas along Georges Bank.

But others urge caution. “This is something we haven’t encountered before, so we don’t have a lot of information,” said Mary Beth Tooley, executive director of the East Coast Pelagic Association, which represents most of the herring boats. “Before we come up with restrictions, we need to know what the real biological effect is on the haddock fishery.”

Possession of just one haddock by herring trawlers is a federal violation. The industry may be open to setting caps on the amount of haddock the trawlers can take, but Tooley said more study is needed to determine if the haddock situation is a one-year anomaly or a long-term change.

In the meantime, marine patrols from Maine, New Hampshire and Massachusetts have stepped up enforcement, and Cohen will present his recommendations on the August violations at the council’s meeting. The ship owners and captains, said Cohen, could be charged with possession of bycatch and fined up to $120,000, but no decision has been made.

It all began Aug. 10, when Maine officers boarded the Providian, a 113-foot trawler docking in Portland, Maine, to unload its 900,000 pound catch of foot-long herring. According to estimates, about 2 percent of the catch was young haddock.

That same day, officers checked the trawler Sunlight, when it docked in Rockland, Maine. They estimated that 4.5 percent of the Sunlight’s 290,000-pound herring catch was young haddock.

Both ships got warnings from the state for possessing undersized fish.

Since July 16, state and federal agents have checked 12 herring vessels and found haddock bycatch in nine of them. But in all but those two cases, they found very small amounts.

NOAA Fisheries observers, who have covered 56 herring boat trips this year, have seen little illegal activity, according to program director David Potter. And, Maine Marine Patrol Col. Joe Fessenden added, “We haven’t had any real problems. They know we’re monitoring this so there is a real incentive to be careful.”

It’s a small industry, with about a dozen vessels accounting for nearly 90 percent of the herring catch. The trawlers drag nets through the middle depths, then use hydraulic pumps to rapidly pull the fish into holding tanks.

They need to scoop up vast amounts of the small fish quickly and efficiently to make the 6-cents-per-pound price worthwhile. Any haddock caught in the process are discarded, while the herring provide as much as 70,000 metric tons of bait for the lobster industry.

Meanwhile, the region’s 1,400 hook and line fishermen, using much smaller boats, haul in their haddock one by one and cringe when hundreds or thousands of pounds of their future livelihood are destroyed.

For them, a 20-inch haddock is worth about $2.50 per pound, and on a good day they can catch as much as 6,000 to 8,500 pounds of fish.

Peter Baker, spokesman for the Cape Cod Hook Fishermen’s Association, said his group is planning to file an emergency petition with NOAA Fisheries seeking an immediate ban on herring trawlers from areas that are closed to groundfishing. And they will ask the New England council to change the regulations that allow trawl gear in closed areas.

Herring trawlers can fish in stock rebuilding areas closed to groundfishermen because experts assume the herring trawl nets, which are dragged closer to the surface, won’t capture fish like young haddock that hug the bottom.

“Our guys are just hanging on until they can catch this year’s class of haddock and they see their future growing up in those closed areas,” said Baker. “If they don’t let guys with rods and reels go in there, they shouldn’t be allowing big boats with nets.”

The New England council meeting is set to hear testimony on the matter Sept. 16 but is unlikely to come up with any immediate answers.

“We’re trying to get a grip on the scope of the problem,” said NOAA Fisheries spokeswoman Teri Frady. “There’s not much we can do quickly.”