There was a time when fishermen cursed if they caught a spiny dogfish. The little sharks, 2- to 3-feet long, would steal bait from hooks set for valuable fish, or chew through a trawler's prized catch before the nets could be hauled in. Worse yet, the oceangoing pests seemed to be everywhere.

But as catches of cod, haddock and other desirable fish declined over the years, consumers developed a taste for the lowly dogfish. In England, it's likely to be the fish in "fish and chips." Commercial fishermen here and abroad have responded by targeting a species once reviled as "trash," with catches increasing almost tenfold since the late 1980s.

Although fishermen say they're still plentiful, scientists insist the spiny dogfish is in deep trouble. Annual government surveys show a sharp decline in the number of female dogfish all along the Atlantic coast, while young fish, or "pups," have virtually disappeared. That bodes ill for the future, scientists say.

"It's hard for people to recognize that there's such a real threat," says Michael Sissenwine, director of scientific programs for the National Marine Fisheries Service. "They're still relatively abundant. ... It's a problem you really can't see."

The dogfish debate highlights a continuing controversy over the management of fisheries here and abroad. An article in the journal Nature recently argued that worldwide "industrialized" fishing has reduced the number and size of cod, halibut, tuna, swordfish and other large fish by as much as 90 percent over the past half-century.

At a protest last week in Baltimore, conservationists complained that commercial interests have dominated the debate over fishery regulation since the 1970s. As a result, they said, 60 percent of commercially important U.S. fish stocks are severely depleted. "The U.S. management system is just not working," said Matt Rand of the National Environmental Trust.

He echoed a report this summer from the Pew Oceans Commission, an independent group of experts financed by the Pew Charitable Trusts, which called for reforms in how the United States handles its fisheries.

Industry spokesmen and government officials dispute charges that the oceans are being overfished. But conservationists say the dogfish proves their point: Although some stocks are recovering through improved management, federal and state laws fail to ensure that all fish are harvested in a sustainable manner.

"This doesn't bode well for other species, and especially sharks," contends Sonja Fordham, fish conservation project manager for the Ocean Conservancy, based in Washington.

Sissenwine acknowledges that regulators haven't done enough to preserve the spiny dogfish, despite drafting a plan to rebuild the population. "There's a lot of good science that says we need to lower the catch, or it isn't going to be sustained in the long term," he said.

Commercial dogfish operations were sharply curtailed three years ago when scientists warned that the species was in serious jeopardy. But this year, officials from Massachusetts -- home of the coast's largest dogfish fleet -- persuaded the Atlantic States Marine Fisheries Commission to let fishermen working inshore catch up to 8.8 million pounds of spiny dogfish in the coming year -- more than twice the earlier limit. States regulate fishing within three miles of their shoreline, while the federal government controls catches from 3 miles to 200 miles out.

Massachusetts officials argued that there were flaws in the federal dogfish count.

How are fish counted in the ocean? Federal scientists at Woods Hole, Mass., base their assessments of Atlantic fish stocks largely on semi-annual trawling surveys. Two research trawlers operated by the National Oceanic and Atmospheric Administration drag nets along the ocean bottom for 30-minute intervals at hundreds of randomly selected spots from Cape Hatteras north to Canada. They count, measure and weigh every fish hauled aboard, adding to a compendium of fish-sampling data that stretches back into the 1960s.

Fishermen -- who have chafed at severe restrictions and even closure of some of their most valuable fisheries on Georges Bank and in the Gulf of Maine -- say the surveys undercount the fish. NOAA biologists use outdated trawling methods and gear, fishermen charge, and don't sample where the fish are likely to congregate.

The scientists counter that they sample the water at random, rather than search for fish using sonar, to get a true picture of abundance. They use the same gear and methods year after year, they say, so they can reliably track trends.

The latest flare-up occurred last year, when NOAA officials acknowledged that the Albatross IV's bottom-dragging net wasn't deployed evenly during the winter and spring surveys off New England. Industry officials labeled the error "Trawlgate," but subsequent reviews by independent scientists determined that it did not invalidate the results.

"I think it was a lot about nothing," said Jon Volstad, a specialist in fish population dynamics for Versar Inc., a consulting firm based in Columbia. Volstad, whose firm does work for government and industry, participated in one of the scientific reviews. He noted that fish move around a lot and are not evenly distributed.

"There will always be some uncertainty, but in general [National Marine Fisheries Service] has good survey techniques," he said. Survey data aside, regulators sensitive to the fishermen's economic plight sometimes bend scientists' recommendations on what is a sustainable catch.

"Fishermen are in a bad spot," notes Robert Beal, interstate fisheries manager for the Atlantic States Marine Fisheries Commission. "Allowing another 4 million pounds of dogfish is a help for those guys."

But the decision will only exacerbate the looming dogfish disaster, federal scientists warn. That's because fishermen are going after the largest of the species, and females grow faster than the males. Annual trawl surveys have tracked a 75 percent decline in female dogfish since 1998, and for the past seven years they have turned up very few young.

Like other sharks, spiny dogfish are slow to mature, taking 12 years to reach reproductive age, and they bear young every other year. That makes them highly vulnerable to overfishing, experts say.

Though unable to block the reopening of commercial dogfishing in state waters, the National Marine Fisheries Service on July 17 imposed a ban on taking dogfish from federally managed waters.

The federal closure will ease, but not erase the impact of the state's action, since many fishermen work only inshore waters. "Whatever we do now," Fordham warns, "the population will still decline because there are no pups coming in."