But, will they come when you call them...

...fish...from the vasty deep:

Researchers at the Marine Biological Laboratory (MBL) at Wood's Hole, Massachusetts, are testing a plan to train fish to catch themselves by using a sound broadcast to attract them into a net.

They hope to release fish into the open ocean, where they would grow to market size, before enticing them into an underwater cage to be harvested when they hear a tone that signals feeding time.

If successful, the system could be used to bolster depleted fish stocks and reduce the costs of fish farming, scientists said.

"It sounds crazy, but it's real," said Simon Miner, a research assistant at MBL.

Mr Miner said the first step in the project was to establish whether fish could be trained.