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Net Gains from Self Catching

by Ellen Hardy
26 March 2008, at 12:00am

BOSTON - Scientists are testing a plan to train fish to catch themselves and if it works, the system could have significant implications to aquaculture and sea fisheries.

Reported by Jay Lindsay for the Associated Press, this 'sound system' could eventually enable black sea bass, a much prized restaurant dish, to be released into the open ocean. Here they would grow to market size, until they are lured by sound back into an underwater cage to be harvested.

"It sounds crazy, but it's real," said Simon Miner, a research assistant at the Marine Biological Laboratory at Wood's Hole, which received a $270,000 grant for the project from the National Oceanic and Atmospheric Administration.

Miner said the specially trained fish could someday be used to bolster depleted black sea bass stocks. Also, the farmed fish might become better acclimated to the wild if they can be called back for food every few days.

However the main aim is to reduce the costs of fish farming, an increasingly important source of the world's seafood. If fish can be trained to return to the farmer after feeding in the open ocean for several days, producers could save money on feed and reduce the amount of waste released in concentrated areas.

But the key question is, how many fish will actually return, and how many will be lost to predators or simply swim away?

Randy MacMillan, president of the National Aquaculture Association, said fish farmers won't be easily convinced to adopt open-ocean ranching.

"The commercial side is going to be skeptical," said MacMillan, who works on a trout farm in Idaho.

The Massachusetts project is one of several experiments funded by the federal government last year as part of aquaculture research.

"We're looking for innovations that will actually make a difference for coastal communities and the environment. It fits in both," said Michael Rubino, manager of NOAA Aquaculture.

Previous experiments have used sound to train a fish to feed. In Japan, scientists have used sound to keep newly released farmed fish in certain areas, where they could be caught in traditional ways. But no one has ever tried to get fish to leave and return to an enclosure where they can be scooped up.

The project began last summer using 6,500 black sea bass. Miner said the first objective was to see if the fish could truly be trained. He got his answer after keeping the fish in a circular tank, then sounding a tone before he dropped food in an enclosed "feeding zone" within the tank that the fish could enter only through a small opening.

Researchers played the tone for 20 seconds, three times a day, for about two weeks. Afterward, whenever the tone sounded, "you have remote-control fish," Miner said. "You hit that button, and they go into that area, and they wait patiently," he said.

View the Associated Press story by clicking here.

Ellen Hardy