Abstract
Responses to low-frequency (50-200 Hz), pulsed sounds were observed in reef sharks (Ginglymostoma cirratum, Sphyrna tiburo), pelagic sharks (Carcharhiniis falciformis), and in several species of groupers (Mycteroperca bonaci, M. venenosa, and Epinephelus striatus). By three criteria for positive responses, (i) number present, (ii) closeness of approach to transducer, and (iii) attentiveness of behavior, sharks and groupers of reef areas scored higher during periods of sound playback than during control (quiet) periods. Pelagic silky sharks were attracted to low-frequency, pulsed sounds and apparently habituated to them on both an intra-daily and inter-daily basis. Acoustic responses were suspected when certain sharks and groupers were observed to be attracted to speared, struggling fish and to schools of fish feeding in an excited manner.
