Abstract:
Fish TV is a three-dimensional acoustical imaging system that has been used successfully to measure the swimming trajectories of individual zooplankters in situ [Jaffe et al., Deep Sea Res. 42, 1495--1512 (1995); McGehee and Jaffe, ICES J. Mar. Sci. 53, 363--369 (1996)]. In order to observe zooplankton behavior at various times of day and night, Fish TV was deployed in July 1994 on an open-water mooring (water depth 280 m) in the Gulf of Aqaba, approximately 1 km from Eilat, Israel, at 27 m depth. Data were collected over several days. Analysis of these three-dimensional acoustical images has resulted in the measurement of thousands of animal (mostly euphausiid) trajectories. The trajectories reveal the behavior of these individuals as they forage during the night in the photic zone, and as they make their downward vertical migration before dawn. [Work supported by the Office of Naval Research, the U.S.--Israel Binational Science Foundation and the National Science Foundation.]