This year the National Oceanic and Atmospheric Administration, which regulates fishing in federal waters, began requiring fishermen in the Gulf of Mexico to use another innovation: hooks that are robust enough to catch “target” species like yellowfin tuna or swordfish but bend and release when grabbed by heavier species like bluefin tuna.

Chris Rilling, a fishery biologist at NOAA, said experiments by researchers and fishermen showed that these “weak hooks” reduced bycatch of bluefin tuna in the gulf by 56 percent — a considerable success, he said, because bluefin tuna are severely overfished and the Gulf of Mexico is a major spawning ground.

Elsewhere, he said, the agency is moving to require the use of the circle hook, so called because “it largely comes around and wraps back on itself,” unlike conventional J-shaped hooks. When they were adopted in Hawaii, he said, sea turtle bycatch fell by more than 80 percent, so “we have really been pushing for circle hooks all over the world.”

Mr. Rilling said the government had a host of other proposals to reduce sea turtle bycatch, including requiring boats fishing for albacore tuna to keep hooks at least 100 meters (328 feet) below the surface — where, he said, they will be “out of the way of the turtles.”

“This comes back to the fishermen telling us when, where and how they set their gear where they don’t have much bycatch and trying to get those lessons learned and get them more widely adopted,” said Mr. Rilling, who fished for salmon, herring and halibut in Prince William Sound, Alaska, in the 1980s and ’90s. “They know how they interact with their gear.”

Another gear modification was invented by two Rhode Island fishermen, Phil Ruhle and his son Phil Jr., with the help of gear researchers at the University of Rhode Island. The Ruhles fished for haddock, which NOAA describes as a relatively healthy fish stock, and wanted to avoid catching cod, a depleted species.