Scientists teaching freed fish to respond to calls to come home

US scientists are trying to train young fish to respond to programmed sounds so that they can be released into the ocean and come back when they are ready to be harvested.

Scientists at the National Oceanic and Atmospheric Administration research station at Woods Hole, Maine, are training 5,000 hatchery-raised black sea bass to respond to 20 seconds of programmed sounds in the hopes they would remember it when they are grown up in the wild.

The agency is spending US$270,000 on the experiment, one of several it is undertaking to improve aquaculture.

The goal is to avoid incurring the costs of feeding the bass as they grow into adults. Fish raised in such a manner would also be more environmentally friendly and humane than fish farm operations.

Fish farms could profit even if just half the number of released fish came back, according to Scott Lindell, the director of the Marine Biological Laboratory's Scientific Aquaculture Programme,

Currently, sustainable harvests of fish can meet just 70 percent of the world's demand.