Abecasis, D. Movements of four sparid species inside Ria Formosa using conventional tagging and acoustic telemetry.

Ria Formosa is one of the largest lagoon systems on the Portuguese coast. This type of habitat is considered particularly vulnerable to destruction and degradation mainly because of human activities. This makes the knowledge of the ichthyofauna, and particularly the way it uses this system extremely necessary to proceed with an adequate management of the system and the species. Being so, the main objectives of this study were to determine the suitability of the use of acoustic telemetry and conventional tagging on the study of the movements and habitat use by four of the most important sparid fishes that inhabit Ria Formosa. Preliminary results on movements, home range and activity period of Diplodus vulgaris, Diplodus sargus, Sarpa salpa and Sparus aurata were ensuing objectives. Results on conventional tagging (n=1980) showed that juveniles of D. vulgaris and S. salpa perform small displacements demonstrating high site fidelity. The small number of recaptures of tagged D. sargus and S. aurata did not allow any conclusions. The use of acoustic telemetry (n=21) allowed us to observe that D. vulgaris and D. sargus show high site fidelity, with the first having a smaller home range. In contrast, S. salpa dispersed throughout the study area. S. aurata showed homing abilities after being released 3,8 km away from the capture position. Two different behavioral patterns were noticeable, some individuals being more active during the night while others were more active during the day.