Virginia Inst. of Marine Sci., College of William and Mary, Gloucester Point, VA 23062
Auditory capacities of the Atlantic Loggerhead (Caretta c. caretta) were assessed to develop a sound repelling system to be used in dangerous areas. To estimate sensitivity, auditory brain-stem responses (ABRs) were recorded in ten animals to clicks and tones (250, 500, 750, and 1000 Hz). Animals, removed from water, had electrodes implanted subcutaneously. Stimuli were presented to eardrum with a vibrator. Consistent responses occurred within the first 10 ms after stimulation, not unlike that recorded in nonmarine forms. ABR waveforms increase in latency with stimulus attenuation. Prior to ABR recording, sound-induced head movements were noted in most, but not all animals. Sound-induced swimming was also observed. A flight response within the artificial environment of a small tank may not predict natural behavior, hence animals will be placed in a saltwater pen and the experiments repeated with a sound source away from the animal. Finally animals fitted with transmitters will be released in the lower Chesapeake Bay. After settling into a selected area, they will be approached by a moving sound projector to determine if this sound induces flight.