THE DIET OF LUTJANUS-COLORADO (PISCES, LU TJANIDAE) IN GOLFO-DE-NICOYA, COSTA-RICA

A total of 308 ''Red Snapper'' Lulianus colorado were collected monthl y in the Gulf of Nicoya, Costa Rica, from January 1993 to January 1994 to determine feeding habits. The fishes (16-56 cm in total length) we re collected with a push-net and hook and line. A total of 16 fish spe cies and 14 crustaceans, as well as molluscs, polychaete worms and pla nt debries were found in the stomach contents. The total biomass was 9 84.2 g; 40% of the stomachs were empty. The diet has ontogenic differe nces: in juveniles, at any time of the year, the most frequent and abu ndant components were fishes (i.e. Anchoa sp., Tomicodon sp. and Pomad asys sp.), and in adults they were penaeid shrimps (i.e. Penaeus calif orniensis, P. occidentalis and P. stylirostris). The main food of the bigger fishes (greater than or equal to 50 cmTL) were stomatopods (Squ illa sp.). The relative importance of different components of the diet was assessed with two indexes that combine, in different ways, percen tage frecuency of occurrence, percentage number and percentage weigth of prey categories. The relative importance and feeding coefficient of the main dietary items did not vary during the year.