The researchers said recreational fishing takes 59 percent of the red snapper in the Gulf of Mexico, 93 percent of red drum in the South Atlantic and 87 percent of bocaccio on the Pacific coast.

"With over 10 million saltwater recreational anglers in the U.S., and recreational fishing activity growing as much as 20 percent in the last 10 years, their aggregate impact is far from benign," said Will Figueira of Duke University in North Carolina, who worked on the study.

They hope their report, based on U.S. government data and published in the journal Science, will provide a wake-up call to regulators and to fishing enthusiasts about the damage being done to fish stocks.

"The conventional wisdom is that recreational fishing is a small proportion of the total take, so it is largely overlooked," said ecologist Felicia Coleman of Florida State University, who led the study.

Duke's Larry Crowder noted the impact of recreational fishing was startling both to researchers and the anglers, who often head out to sea in boats operated by professional guides and equipped with sonar devices and global positioning systems to locate the fish.

"Recreational anglers are operating below the radar screen of management. While the individual may take relatively few fish, we show that a few fish per person times millions of fishermen can have an enormous impact," he said.

When they looked at fish designated as species of concern by the U.S. government, sport fishing accounted for 23 percent of the take by weight, Coleman said.

MORE EFFECTIVE REGULATION

The researchers call for more effective regulation of sport fishing.

"I don't think they are saying anything new," Mike Sissenwine, director of scientific programs at the National Marine Fisheries Service, said in a telephone interview.

"I didn't know what the (overall) number was, nor do I think that anybody cares. But we were very well aware that for some species the impact is important, and therefore it is taken into account in fisheries management."

In April, the U.S. Commission on Ocean Policy issued a report saying North America's oceans are in serious peril due to pollution, overfishing and poor management.

"Yes, we already do regulate recreational fisheries," said Andy Rosenberg of the University of New Hampshire and a member of the commission.

"But there has been an increase in recreational fishing. More people want to do it and more people have access to the coast," he said in a telephone interview.

Rosenberg agreed that more comprehensive regulations are needed.

Nearly half the coastal states do not require salt-water recreational fishing licenses.

Catch-and-release programs may not help, either. The report cites NMFS data that show 20 percent of released fish end up dying. And many individual fish are caught repeatedly.

"A Goliath grouper near one of my study sites had 20 hooks in its mouth," said Coleman.

"Bringing up a 400 pound (200 kg) fish onto your boat creates a marvelous photo opportunity, but it undoubtedly causes enormous physiological stress on the fish. And catching it is about as exciting as pulling up a Volkswagen."

The Recreational Fishing Alliance, a Washington-based lobby group, had no immediate comment on the report.