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Volume 44 - Number 2 - 2009

Distribution, relative abundance and feeding of narrow-mouthed catshark Schroederichthys bivius Müller & Henle, 1838 in the Southwest Atlantic Ocean

Felisa Sánchez1, Noemí R. Marí1 y Juan C. Bernardele1


1Instituto Nacional de Investigación Pesquera (INIDEP), Paseo Victoria Ocampo N°1, (B7602HSA), Mar del Plata, Buenos Aires, Argentina




The narrow-mouthed catshark, Schroederichthys bivius, is a cartilaginous fish that inhabits the Southwest Atlantic Ocean ranging from 34°S to 54°S at depths from 45 to 350 m. Like other chondrichthyans, it is caught as by-catch in fisheries of other target species, in research cruises as well as in commercial fleet. Information from 1924 fishing trawls of research cruises performed for INIDEP, carried out from 1996 to 2006, was analysed. Data was obtained in two areas: northward (PBN) and southward (PPA), both in different seasons. Biomass values estimated in PPA were three times superior to PBN area. S. bivius presented a wide distribution without seasonal variations but its frequency of apearance and its relative abundance showed a southward increasing trend. Values of relative abundance were between 0.010 and
9.1 t mn-2, being 97% of these values lower than 3.0 t mn-2. In order to determine feeding habits a total of 736 stomachs were analysed. A total of 88% of sampled individuals evidenced food ingestion. General trophic spectrum consisted on cephalopods (39%), fishes (36%), benthic crustaceans (18%), other benthic invertebrates (6%) and gelatinous zooplankton (1%). In PBN, fishes were principal prey whereas cephalopods were in PPA. Although no differences were observed in diet composition between males and females, a diet shift was observed near 64 cm TL. General trophic level estimated was 3.25


Key words: Argentine sea, chondrichthyans, trophic spectrum, trophic level



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