Hábitos alimenticios del pargo amarillo Lutjanus argentiventris y del pargo rojo Lutjanus colorado (Pisces: Lutjanidae) en el norte de Sinaloa, México

The biology and ecology of the species Lutjanus colorado and Lujanus argentiventris is almost unknown in the state of Sinaloa Mexico, in spite of the economic importance that catch of these species had in the year 2000 with 233,642 metric ton. The present work is of scientific importance by the biological contribution for the managing of these fisheries. Stomachs of these species were monthly collected from artisanal and personal catches during 2001. A total of 145 stomachs of L. argentiventris and 87 of L. colorado were analyzed. The stomach content was identified, separated in groups, quantified, weighted and the frequency of appearance obtained. Additionally, the total and monthly index of relative importance (IRI) was calculated, by sex and size. The diet of these fishes was constituted by two main trophic groups: fishes and crustaceans. The most important prey in the diet of L. argentiventris was Penaeus sp. (Decapoda Natantia) and in L. colorado was Goniopsis pulchra (Decapoda Reptantia). The amount of preys was greater in the summer months, being observed a greater variety of the nutritional spectrum. Numerical and gravimetric percentages were used to determine trophic spectrum diversity. These values were low (<0.5), concluding that the diet of these species is of low diversity but abundant.