Effect of larval density and feeding sequence on meagre (Argyrosomus regius; Asso, 1801) larval rearing

This paper summarizes results from two comparative studies of the effect of initial larval density and feeding sequence on meagre (Argyrosomus regius) rearing trials. To determine the density effect, two initial larval densities of 50 larvae L−1 and 100 larvae L−1 were established. For each larval density, three feeding sequences were tested, applying different combinations of rotifers (Brachionus sp.) and Artemia sp. at different larval ages. Every 4 days, standard length (SL) and body height (BH) of 25 larvae per treatment were measured. After 30 days after hatching (dah), dry weight (DW) and final survival were determined. Biochemical analysis was performed to determine, ash, protein, lipid content and fatty acid composition from preys, microdiets and larvae at 30 dah from different treatments. The lower larval density, promoted better growth in terms of standard length, body height and dry weight. Early Artemia introduction improved also larval growth. A positive interaction was found between rearing density and feeding sequence. Final survival was also affected by initial larval density and feeding sequence. The best final survival (53.4 ± 12.03%) was obtained in high larval density treatment, while early Artemia introduction reduced final survival (36.75 ± 3.62%). Regarding larval biochemical composition, no significant differences were found in ash, lipid and moisture content among treatments, while significantly higher protein content was measured in larvae reared under low density conditions. Furthermore, no significant interaction was found among density and feeding sequences on biochemical composition, and no significant differences were detected on total fatty acid composition.