Shark bites cases of mistaken identity November 16, 2009 at 11:10 PM EST - Updated June 21 at 7:25 AM By Juan Carlos Fanjul - bio | email WEST PALM BEACH, FL (WFLX)-- Palm Beach Atlantic University Biology professor Dr. Ray Waldner says sharks are not out to get humans. "If the water is dirty, they may mistake a person a case of mistaken identity," said Waldner. They like bait fish, but if you are in their way or they can't make out the difference between prey and swimmers, you could get hurt. "They're inquisitive. They know there is a disturbance in the wake and they may feel something, see something. But when they figure out it's not something they want to eat, they go away," he said. Waldner advises swimmers avoid swimming with bait fish or if the water is disturbed. Always stay in groups; sharks are more likely to attack a lone person. Avoid being in the water during dawn or dusk, when sharks are most active. Do not enter the water if bleeding or menstruating. Be cautious between sandbars or near steep drop-off's, a favorite hangout of sharks. If you dare to swim where there are sharks you may want to use an electronic shark deterrent. Adam Davelle, with the Jupiter Dive Center and an avid surfer himself, swears by the device which can be attached to your ankle or a surf board. It emits an annoying sound that frightens sharks. "It has an electrical pulse that works as a shield around you. It keeps them at bay in a 15 foot radius," said Davelle.