Diet of the exotic Gulf toadfish (Opsanus beta) in São Vicente Bay

Abstract

The introduction of invasive species is one of the main threats to biodiversity. Opsanus beta has frequently been recorded as an invasive species in several regions, including the southern and southeastern coasts of Brazil, especially in port areas. In this study, we analyzed the diet composition of O. beta collected in São Vicente Bay, using the Feeding Preference Index to quantify the consumed items. A total of 22 food items were identified, with fish and crustaceans being the main groups recorded, along with the occurrence of cannibalism. The results were similar to those reported for other species in the Batrachoididae family, such as Porichthys notatus, Halobatrachus didactylus, and O. beta in its native range in Mexico. In these species, cannibalism differs according to the developmental stage of the prey, occurring on embryos in P. notatus, eggs in H. didactylus, and juvenile individuals in O. beta. Thus, our study characterizes O. beta as an omnivorous, generalist, and opportunistic species, based on the diversity of food items identified and the predominance of items classified as occasional. These feeding traits reinforce the species’ potential ecological impact in environments where it acts as an invader.