Biomass and fishing potential yield of demersal resources from the outer shelf and upper slope of southern Brazil

• Autor(a) principal: Haimovici, Manuel
• Data de Publicação: 2009
• Outros Autores: Fischer, Luciano Gomes, Wongtschowski, Carmen Lúcia Del Bianco Rossi, Bernardes, Roberto Ávila, Santos, Roberta Aguiar dos
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da FURG (RI FURG)
• Texto Completo: http://repositorio.furg.br/handle/1/2410
• topic: Demersal fishes; Stock assessment; Biomass; Brazil; Peces demersales; Evaluación; Biomasa; Brasil

The relative abundance and fishing potential of the commercially valuable fishes and cephalo-pods with marketable size was assessed using two seasonal bottom trawl surveys performed in 2001 and 2002 on the outer shelf and upper slope (100-600 m depth) off the coast of southern Brazil. These surveys were part of REVIZEE, a national program designed to assess the fishery potential within the Economic Exclusive Zone. Of the 228 fish and cephalopod species caught during the surveys, only 27 species and genera were considered to be of commercial interest. Commercial-sized individuals of these species made up 52.3% of the total catch. The total biomass was estimated to be 167,193 ton (± 22%) and 165,460 ton (± 25%) in the winter-spring and summer-autumn surveys, respectively. The most abundant species were the Argentine short-fin squid Illex ar-gentinus, a species with highly variable recruitment, followed by the Argentine hake Merluccius hubbsi, the gulf-hake Urophycis mystacea, and the monkfish Lophius gastrophysus. The latter three were intensively fished prior to the surveys, as well as the beardfish Polymixia lowei and silvery John dory Zenopsis conchif-era, both relatively abundant but with a very low market value. The potential yield of the demersal fish spe-cies, not considering Illex argentinus, estimated with the Gulland equation for a mean natural mortality of M = 0.31, was 20,460 ton. When considering only Merluccius hubbsi, Urophycis mystacea, and Lophius gastro-physus, the potential yield decreased to 6,625 ton. The surveys showed that the fishery potential of the outer shelf and upper slope was substantially lower than that of the inner shelf. Therefore, this environment should be carefully monitored to avoid overfishing and fast depletion. Keywords: demersal fishes, stock assessment, biomass, Brazil.