CONICET | Buscador de Institutos y Recursos Humanos

The Narrow-mouth Catshark, Schroederichthysbivius, is an oviparousspecies endemic of Sourth America. This species is frequently caught asby-catch by bottom-trawl nets in Argentine fisheries. It is catalogued as ?DataDeficient? species by the International Union for Conservation of Nature (IUCN).Currently, little is known about the trophic ecology of this shark. The mainobjective of the present work is to studying the diet of S. bivius by analyzing the stomach content on the northernArgentinean continental shelf (between 35°S y 41°S). Specimens were capturedduring spring 2016 on board a research cruise carried out by National Instituteof Research and Development (INIDEP) in Argentina. Stomachs were analyzed atthe laboratory. Prey items were identified to the lowest possible taxonomiclevel, counted and weighted. In order to quantify the diet of S. bivius, the frequencyof occurrence (%F), the percentage of number (%N) and the percentage of weight (%Mi)and the percentage of the index of relative importance (%IRI) were estimated. Preliminaryresults indicate that from 143 stomachs of S.bivius analyzed, 100% contained food. The Narrow-mouth Catshark, S. bivius is a benthic feeder. Thediet consist mainly in crustaceans (56.6 %IRI), followed by polychaetes(18.65 %IRI) and fish (18.09 %IRI). Among crustaceans, the most importantidentified prey was euphausiids Eupahusia spp. (25.77 %IRI), the redcrab Libidoclaea granaria (12.65 %IRI), and the hyperiid amphipod Themistogaudichaudii (5.38 %IRI). The most important fish in the diet of S.bivius was the Nototheniid Patagonotothen ramsayi (6.61 %IRI).Variations in the diet were evaluated by fitting generalized linear models (GLM). The Narrow-mouth Catshark,S. bivius is a mesopredatorspecies with trophic level of 3.6.