Primer registro de un predador natural sobre la especie Genidens barbus (Lacépède 1803), en el río Negro, Río Negro (Argentina)

Abstract

he diet and feeding behaviour of a species determine its trophic position and define its ecological role. It also constitutes a key factor in structuring and maintaining the stability of communities. Due to the presence of external bone structures in fishes belonging to the Ariidae family, there are few predation records within the group, except for some cases in marine mammals and sharks. Genidens barbus is an anadromous species, with a complex reproductive cycle. It belongs to the Ariidae family and has great commercial value in Brazil where it is heavily exploited, to the point that it has been included in the red list of threatened species. However, knowledge regarding the status of its stock, distribution, natural predators and bioecology is limited. Thus, the aim of this work is to report the first evidence of a natural predator of the marine catfish G. barbus, the sea lion (Otaria flavescens), in the Río Negro estuary, Río Negro, Argentina. We examined a video recording made by a fisherman in December 2019. The feeding behaviour of the sea lion involves the capture of the prey by the posterior region, in a similar way to that observed by Tursiops truncatus in the Gulf of Mexico. More studies regarding food webs and population status of the catfish G. barbus in the Río Negro estuary are needed.