AN ACOUSTIC TELEMETRY STUDY OF SEABREAM (SPARUS-AURATA L) - FIRST RESULTS ON ACTIVITY RHYTHM, EFFECTS OF ENVIRONMENTAL VARIABLES AND SPACE UTILIZATION

The movements of seabream (Sparus aurata L) were recorded in two earth en ponds (250 m(2) and 400 m(2)) by tracking fish tagged with miniatur e acoustic transmitters. Five seabreams, 500 g in weight, were tracked for periods of four or five days. Fish positions were recorded contin uously using an acoustic telemetry system. Each of the five tagged sea breams were tracked individually. Two fishes were released schooled wi th numerous other individuals, two others were released in isolation a nd one was grouped with three other individuals. The schooled seabream s were more active in general and, in the large school they were diurn al; isolated fishes however, were more active at night. Temperature in fluences significantly and progressively the fish activity. Activity d ecreases at night and increases during daylight. Oxygen saturation als o influences swimming activity with a general positive relationship. T he horizontal distribution of this species was not uniform. Its restin g area was generally located around some particular landmarks such as inlet or outlet pipes in the ponds. No feverish feeding competition wa s observed between individuals of the same school. The feeding area wa s cleaned rapidly, in less than 10 minutes, without subsequent returns from the resting area to the feeding area.