Quali-quantitative composition of "mistura" category on the double rig otter trawl fishery landed in Santos and Guarujá, São Paulo, Brazil

Abstract

In southeastern Brazil, the coastal demersal fishery resources are exploited mainly by the pair trawler and double rig otter trawler fleet (bottom trawl). The bottom trawl are multispecific fisheries, catching a great number of species, beside target species. Among the categories (species) landed, the so called "mistura†is composed basically by low commercial value species, as well as small sized individuals of the commercially important species. This category is one of the three main categories landed for trawler fleets of Sao Paulo State, requiring more studies about its composition. In this study, the importance in the species composition of the otter trawl landings, from June 2001 to May 2002, was defined by the analysis of the IRI (Index of Relative Importance) percentage. In the samples were identified 48 species from June 2001 to May 2002, standing out Orthopristis ruber (%IRI=19.4), Pagrus pagrus (%IRI=14.9), Diplectrum formosum (%IRI=14.4) and Umbrina canosai (%IRI=10.8). An increase in the species was observed in the "mistura†composition of otter trawl fishery in relation to previous studies. The relationship between the weight of each species as "mistura†and the total catch landed by each species was analyzed, presenting values between 4.8% to 99.7% of increment. The lack of species discrimination of the "mistura†category in the landings, can lead to a wrong evaluation of exploitation impacts on these species, mainly on the commercially important such as Micropogonias furnieri, U. canosai, Menticirrhus americanus, P. pagus and Prionotus punctatus.