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Field and laboratory studies were conducted on the use of underwater sound as a means to cause rapid withdrawal from an operating sound source by various species of sharks found in the Florida Straits, Tongue of the Ocean, Bahamas and associated reef tracts. The study included species of the genera, Carcharhinus and Negaprion. The findings, to date, though preliminary, leave little doubt that, given specific conditions, at least certain species of sharks can be made to withdraw for a reasonable period of time (measurable in mins.) from such a source playing back appropriate-level acoustic signals. (Author)

Series of extensive field experiments were conducted over the deep waters of the Florida Straits and the Tongue of the Ocean, Bahamas to provide information on the differential attractiveness of various acoustic signals in the near sub-sonic range (10 to 20 Hz, 20 to 40 Hz, and 40 to 80 Hz) to free-ranging silky sharks (Carcharhinus falciformis) and oceanic whitetip sharks (C. longimanus). Ambient noise measurements were accurately determined in the study areas. Findings included ambient noise determination from 10 to 1000 Hz, demonstrated preferential attraction by sharks to sounds having a frequency spectrum between 10 and 40 Hz, and behavioral information on both species of sharks, attracted. A summary of all studies on the acoustic attraction of sharks is included in the discussion.

In order to monitor and record the occurrence of marine animal sounds off the west coast of Bimini, Bahamas, a pair of hydrophones, cable connected to an acoustics lab. at the Lerner Marine Lab. on Bimini, were installed in Nov. 1960. One hydrophone was located one mile off shore in water 30 m. deep. The other one was 2 miles off shore in water depth of 350 m. Both hydrophones were mounted on the bottom. Subsequently, in May 1962, an underwater TV camera was installed at the shallow hydrophone location and cable connected to shore. The camera was provided with a zoom lens, flood lights, and focusing means which could be controlled from the lab. A sound projector was also installed near the camera. Lab equipment for photographing the scene and tape recording sound was also provided. This made it possible for other investigators to study the activity in remote locations. During a period of 3 years a number of biologic studies of soniferous animals were successfully conducted attesting to the systems usefullness. Based on the results of these studies, redesign recommendations were made. A redesigned camera system was installed in Aug. 1966, including video tape recording facilities for simultaneously recording sound and scene. The unit, featuring rapid optical pan and tilt and a behavioral studies on sharks, bicolor damselfish, yellow headed jawfish and also snappers and groupers subsequently were carried out and documented.