Neat concept, but it has holes.

1. Fish Pirates - Drop a fake transmitter in the water and steal the trained fish.
2. PETA (or what ever the equivalent is for fish protection groups) - Drop a fake transmitter and put a mild irritant into the water to re-train the fish.
3. Fish develop piranha like aggressiveness, are attracted by whale mating calls and nibble the the flesh off of Orcas.

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.

What's next, teaching them to coat themselves in batter and hop inside a fryer?

"It sounds crazy, but it's real," said Simon Miner, a research assistant at the Marine Biological Laboratory at Woods Hole, which received a $270,000 grant for the project from the National Oceanic and Atmospheric Administration.
Full Article - Fox News: http://www.foxnews.com/story/0,2933,341649,00.html