When it is necessary to do deep soundings in the sea, the powerful blasts kill the fish in that vicinity. Biologists now have a way to frighten fish out of an explosion area and save them from mass destruction. They use an underwater loudspeaker to transmit tape recordings of the sounds usually made by fish that feed on other fish. Most of the fish flee from the danger of being eaten Consequently, the explosion can take place without slaughter of marine life.rr