Dolphins killer sonar confirmed acoustically and visually on videotape:
Marten had noticed before that dolphins close to herring would emit low bangs at the frequency the fish hear best at, and had suggested the bangs were designed to damage the fish’s hearing apparatus. He has now taped a dolphin emitting a sequence of low- frequency “bangs” while chasing a fish.In a further experiment, Marten showed that low sounds with similar acoustic properties to dolphins’ clicks disorientated anchovies to the point where they swam in circles, remained still or died. “It could also mess up their schooling,” he says.
Meanwhile, Herzing has found evidence of a different strategy. She recorded wild Atlantic spotted dolphins emitting a medium-frequency buzz while searching for prey in sand on the seabed. She says buried eels jumped out of the sand, and either stopped completely or moved sluggishly as if they were stunned, giving the dolphin time to catch them.