Feeding and Diet Overlap of Six Estuarine Fishes (Family Carangidae) from the Mexican Pacific Region

Caranx caninus, C. sexfasciatus, Chloroscombrus orqueta, Selene brevoortii, S. peruviana, and Selar crumenophthalmus are species with economic importance for local artisanal fisheries and are regular components of the fish assemblage at Barra de Navidad coastal lagoon in the Pacific coast of Mexico. The working hypothesis was that carangid species in the lagoon share a common food base but the proportion of main food categories in the diet will be different for some groups of species due to differences in key morphological characteristics of the carangids. A total of 1251 individuals were used for diet analyses. Stomach content analyses showed that five species feed on benthic invertebrates and small fish while one species was mostly a plankton feeder. A partial sharing of main food resources was found for most of the studied species, but significant differences in the proportion of food categories in the diet were identified for several groups of species. Another aspect of diet variation was associated with predator size whereby larger individuals tended to consume the largest prey. A plausible explanation for the variation observed in feeding habits is based on morphological differences among groups of species which favor piscivory or planktivory in some cases. This paper is the first published report on the feeding habits of all six species in any Mexican estuarine habitat and of four species in Eastern Pacific estuarine waters.