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Remote controlled fish
Scientists are training fish to return to nets when they hear a tone that signals feeding time. The aim is to release farmed fish into the ocean where they would grow to market size, then swim into underwater cages for capture on cue.
The Associated Press reports that researchers at the Woods Hole Oceanographic Institute received a $270,000 grant from the federal.government for the project. It is one of several being funded as part of aquaculture expansion plans in the U.S.
It's not the first time sound has been used to train fish scientists in Japan, for example, have used the method to keep newly released farmed fish in certain areas, where they could then 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 captured.
The Woods Hole researchers began their project last summer by placing 6,500 black sea bass in a big tank. Over two weeks they sounded a tone for 20 seconds, three times a day prior to dropping food in an enclosed 'feeding zone' within the tank. Afterwards, whenever the tone sounded, the fish gathered in the feeding zone and waited patiently to be fed. Researchers are now trying to figure out how long the fish remember to associate the tone with the food.
In May, 5,000 sea bass will be put into a large "aqua dome" feeding station that will be anchored to the ocean floor in a nearby bay. After they've been trained the fish will be released. A few days later, the scientists will sound the tone and see how many fish return to the dome.
The ultimate goal is to cut the costs of fish farming. If fish can be trained to return to net pens after feeding in the ocean, it could reduce the high costs of feed as well as the amounts of fish wastes released into concentrated areas.
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