Trophic interrelations of the three most abundant fish species from Laguna San Ignacio, Baja California Sur, Mexico

We analyzed the trophic interrelations of cominate sea catfish Arius platypogon, shortfin weakfish Cynoscion parvipinnis, and California king croaker Menticirrhus undulatus from Laguna San Ignacio, B.C.S., Mexico during spring and summer 1992. Four different trophic groups were found on the basis of feeding preferences; crustaceans, fish, mollusks, and polychaetes. Each predator species has a preference for specific prey. For A. platypogon, the dominant prey was Callinectes bellicosus; for C. parvipinnis, the species Penaeus californiensis and Ophistonema libertate were the main prey; and for M. undulatus, the dominant preys were P. californiensis and Donax sp. The food habits of these predator species have some seasonal and spatial changes, however according to the Morisita-Horn index no significant trophic overlap exists. The results of this study show the coexistence of these predator species are a function of a spatial segregation and the distribution of available food resources in the lagoon.