Feeding habits ofEucinostomus entomelasandMicropogonias megalopsin Las Guasimas lagoon Gulf of California

Abstract

The trophic spectrum of bothEucinostomus entomelasandMicropogonias megalops, the two most abundant fish species in Laguna Las Guásimas, Sonora, México is described in our study. A total of 21 types of prey were identified belonging to seven taxonomic groups (Crustacea, Mollusca, Annelida, Rhodophyta, Copepoda, Echinodermata and Chordata) to analyse the feeding spectra and diet breadth. The preferred prey items ofEucinostomus entomelas(Dark-spot mojarra) were Polichaeta (index of relative importance = 46.7%), followed by bivalves(36.6%), andLuidia columbia (5.6%), while those ofMicropogonias megalops(Bigeye croaker) were Portunidae (22.8%) followed by Gammaridae (20.55%) and Crustacea (18.37%). The trophic spectrum for maleE. entomelawas composed of Bivalvia and Polychaeta. Both predators showed low values in diet breadth (E. entomelas(Levin's indexBi = 0.14) andM. megalops(Levins's indexBi = 0.43)). The low trophic overlap (Cλ = 0.14) between predators suggests that both fish are not competing with each other for food resources in Laguna Las Guásimas.