Commercial fisheries in the U.S. kill a pound of fish for every four pounds intentionally caught, jeopardizing efforts to restore some struggling stocks, scientists said Wednesday.

A tally of the nation's yearly unintentional "bycatch" — unwanted fish that are caught and, in most cases, die before being thrown overboard — was conducted by scientists Jennie Harrington, Andrew Rosenberg and Ransom Myers.

Their peer-reviewed study, sponsored by the environmental group Oceana and published in the December issue of Fish and Fisheries magazine, found that 1.1 million tons of fish annually are thrown away as dead with every 4 million tons caught in commercial nets.

"We can and should do better," said Rosenberg, dean of the University of New Hampshire's College of Life Sciences and Agriculture and member of a federal commission that studied ocean policy. "This sort of waste undermines efforts to recover those depleted resources."

Most of the fish — such as skates, monkfish, swordfish, tunas, sharks, salmon and halibut — are snared by shrimpers' nets in the Gulf of Mexico or in the huge trawling nets some vessels use to reach the ocean floor.

The Gulf's shrimpers, for example, catch 114,000 tons of shrimp a year, but discard four times that weight in snappers, mackerel, Atlantic croaker, crabs and porgies.

In response, National Oceanic and Atmospheric Administration Fisheries, part of the Commerce Department, said Wednesday that federal efforts to use newer fishing gear and ways of managing have cut bycatch by 50 percent in the Gulf shrimp fishery and by "substantial" margins in virtually all other U.S. fisheries.

The federal agency, responsible for managing U.S. marine resources from 3 miles to 200 miles offshore, keeps regional bycatch statistics, but does not compile them nationally.

Zeke Grader, executive director of the Pacific Coast Federation of Fisherman's Associations, based in San Francisco, acknowledged the bycatch problem.

He said the government should charge a seafood fee to establish a multibillion-dollar trust fund — an idea proposed by the federal commission and some in Congress — to pay for more selective fishing gear and better fisheries research.

"It's both a concern for other fisherman and for the health of the stocks," he said. "There's no real easy answer."

Myers, a marine biology professor at Dalhousie University in Canada, said the waste inevitably will harm the overall health of the oceans unless it first "wakes up fishery managers to the fact that broad-based action covering all U.S. fisheries is needed."

Harrington is a consultant with Marine Resources Assessment Group in Essex, Mass.