Researchers have for the first time calculated how many fish are killed when fishermen go after more lucrative species and the news is not good. Nationally, for every four pounds of fish that are kept, fishermen discard an unwanted one pound of fish. This is one of the highest by-catch rates in the world and the numbers are even worse for the Northeast. The study shows that senators are on the right track by funding more gear research and, most important, follow up studies, to see if the improvements work in their rewrite of the nation’s fishing regulations, the Magnuson-Stevens Act.

Imagine if a slaughterhouse accidentally killed one horse for every four cows that were dispatched to become hamburgers and steaks. Because fishing is done where few people see what is happening, the public is slow to recognize the scope of problems and slow to demand solutions.

Despite all the recent attention on the New England groundfishery, it has one of the highest by-catch rates. For every 55,000 tons of groundfish brought to port, groundfishermen throw away 98,000 tons at sea, according to the report, published in the current issue of Fish and Fisheries. Fish are discarded for many reasons, including limits on how many can be caught and the fact that they are not valuable. The fish that are most often thrown away include spiny dogfish, monkfish and hake. The fish that are discarded are usually small, young fish.

In New England there have been important efforts to reduce by-catch such as putting juvenile fish habitat off limits to fishing and requiring bigger holes in nets to allow young fish to more easily escape. The problem with these efforts, says Andy Rosenberg, a deputy director of the National Marine Fisheries Service and an author of the current report, is that no one is following up to see how well these measures reduce by-catch. The version of the Magnuson-Stevens Act that Congress will consider next year begins to address this problem.

Other alternatives worth looking at are counting by-catch in overall catch limits, which is already done with yellowtail flounder, and developing markets for fish that are now thrown away. A more stringent approach, advocated by Dr. Rosenberg, a professor at the University of New Hampshire, is to set by-catch limits for each fishery and to shut them down when the limit is reached.

Because gear modifications are supported by the fishing industry, they hold the most promise. Ensuring that changes significantly reduce by-catch could go a long way to solving this problem.