Movement pattern of white seabream, Diplodus sargus (L., 1758) (Osteichthyes, Sparidae) acoustically tracked in an artificial reef area

摘要

This paper presents the results of an application of ultrasonic telemetry on white seabream, Diplodus sargus inhabiting an artificial reef (AR) in NW Sicily (western Mediterranean Sea). The objective of the study was to investigate the movement pattern of seabreams, verify their homing behaviour and site fidelity, determine their home range and describe their use of the habitat. Four seabreams were tagged and released, and their movements were recorded with automated and manual acoustic receivers. The spatial and temporal distribution of positional data suggest that the tagged seabreams hide inside the AR during the day, staying out of their shelter at night. The nocturnal movements of the tagged fishes are suggested to be a search for food in the seagrass patches surrounding the ARs. The monitored seabreams showed clear horning behaviour and strong site fidelity. Their home range extended from 0.01 to 0.17 km and included the AR and the surrounding sandy area with seagrass patches. Home range areas increased proportionally to the distance between the refuge on AR and the foraging areas on seagrass patches. The higher activity of seabreams during the night was interpreted as a result of a trade-off between predation risk and foraging needs.