US scientists train fish to come when called
The Marine Biological Laboratory at Wood's Hole, Massachusetts recently received a grant of US$ 270,000 to test a plan where fish would be trained to return to a net when they hear a sound that signals feeding time. Based on research conducted in Japan, the Wood's Hole scientists hope to be able to keep fish in a specific area where they can be recaptured when they reach market size. The Japanese study was able to keep fish swimming in a location where they then could be caught using conventional fishing gear.
This new experiment is based on releasing hatchery-produced fish into the open ocean, but train them to return to a specific spot or net pen when called, using a sounding device. The experiment- if proven successful- would enable fish farmers to save on feed and other costs, as the fish would "fend for themselves" while away from their regular enclosure.
The project began last summer, using 6,500 black sea bass. The fish lives between Florida and Cape Cod, located in the middle of the State. The species grows up to 3 pounds (~1.4 Kg), although individuals have been caught weighing 8 pounds (~3.6 Kg). The research started in a tank setting, where the fish were trained to enter a "feeding zone" through a narrow opening. The tone was played for 20 seconds three times a day for about two weeks. Afterwards, the fish would come to the zone whenever the tone was played, and patiently wait until the food arrived.
Researchers are now trying to find out how long this association between sound and feed will last. They have been feeding the fish at times outside the "feeding zone" without a tone for a few days, and then they would test the fish to see if they would still head into the zone when the sound was played. Some fish forgot after five days. while others still remembered 10 days later. Field testing will be carried out in the ocean near Buzzards Bay, 45 miles southeast of Boston this summer, using some 5,000 black sea bass.
