EFFECT OF SIZE GRADING ON SEA BASS (Dicentrarchus labrax) JUVENILE SELF-FEEDING BEHAVIOUR, SOCIAL STRUCTURE AND CULTURE PERFORMANCE

摘要

This study aims to test the influence of size grading on self-feeding behaviour, social structure (measured by the % of triggering acts per individual), growth performances, and blood physiological variables of individually PIT-tagged sea bass juveniles, using a computerized on-demand feeding system coupled with a PIT tag monitoring device.Three consecutive periods of 27 days each were compared: a first period (PI) before grading (6 tanks of 100 fish; BW=40.2±8.9 g) followed by a second period (P2) after grading. The protocol applied aimed to create two groups of fish of similar mean weight but with either a low or a high CV of weight (CVw) corresponding to an imposed difference in social disruption (T_(low): CVw ~ 10 %, 3 tanks of 60 fish each with social disruption; TWgh. CVw ~ 20 %, 3 tanks of 60 fish each, without social disruption).T_(low) and T_(high) groups were studied over P2, and an additional 27-day period under identical conditions (P3).