BOSTON – Call them Pavlov’s fish: Scientists are testing a plan to train fish to catch themselves by swimming into a net when they hear a tone that signals feeding time.
If it works, the system could eventually allow black sea bass to be released into the open ocean, where they would grow to market size, then swim into an underwater cage to be harvested when they hear the signal.
“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 the depleted black sea bass stock. Farmed fish might become better acclimated to the wild if they can be called back for food every few days.
The bigger goal is to defray 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, farms could save money on feed and reduce the amount of fish waste released in concentrated areas.
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 an Idaho trout farm.
The project began last summer using 6,500 black sea bass, a stout, bottom-dwelling fish that lives between Florida and Cape Cod and in the winter is generally not found north of New Jersey. The species grows up to 3 pounds and 20 inches long and has a thick, white flesh that can be filleted for broiling or cut for frying.
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.
By May, researchers hope to bring about 5,000 black sea bass to a feeding station called an “AquaDome,” a structure about 33 feet across and 16 feet high that will be anchored to the ocean floor in Buzzards Bay, 45 miles southeast of Boston.
The fish will be fed in the dome after a tone sounds. After researchers feel they’ve been sufficiently trained, they will be freed from the dome. A day or two later, scientists will sound the tone again and see how many bass return.