There is a good article in the NYT by Cornelia Dean about by-catch and changes in fishing gear designed to reduce it:
But new efforts to protect marine creatures have gained surprising support from researchers, regulators, engineers and fishermen.
The issue is bycatch — fish, whales, turtles, sea birds and even corals killed or injured by fishermen in search of other species. The best-known example is dolphin caught in tuna nets, but the problem is far more extensive than that.
“It’s part of the collateral damage fishing causes,” said Tim Werner, who directs the marine conservation engineering program at the New England Aquarium. “You deploy a net and catch a turtle, put out a pot for a lobster and entangle a whale, put out a trawl and pull up coral.”
The problem affects marine species around the world, many of them endangered. Though much attention is paid to overfishing, “often our greatest impact is not on the species we target to catch but the species we did not intend to catch,” Mr. Werner said.
“The seafood on your plate,” he added, “is not the only animal that gave its life to feed you.”
The new efforts focus on modifications to fishing gear. They include relatively simple steps, like changes in hook design, and more complex ones: making fishing lines more visible to whales, changing noise levels on fishing boats and impregnating metal gear with substances meant to repel “bycatch species” like sharks.
read the whole article here