Morfometria da piramutaba (brachyplatystoma vaillantii) desembarcada pelas frotas artesanal e industrial no estuário amazônico

Abstract

The piramutaba (Brachyplatystoma vaillantii) is a freshwater catfish belonging to the Pimelodidae family that performs long migrations from the Amazon estuary, considered its breeding area, and is highly exploited throughout the Amazon. Its maximum known size is 105 cm and its average landed size is between 40 and 50 cm for the 90's. It is fished in the Amazon estuary by two types of fishing fleets: artisanal and industrial. The artisanal fleet uses both gillnets and spinnerets, and the industrial fleet uses the pair trawling method. The present work aimed to estimate the average length of pyramutabas landed by the two types of fleets and whether there are significant differences between these lengths. For this, two sampling points were considered: the Ver-a-Peso market and a fishing industry in Icoaraci. Measurements of furcal length, in mm, were collected monthly at these two sampling points, except during the months when the species was defended by the industrial fishing. During eleven consecutive months, 3,547 length measurements from the artisanal fishery and 2,542 measurements from the industrial fishery were recorded. For the artisanal fishery the smallest recorded length was 210 mm and the largest was 505 mm. The mean overall lengths for all months combined were: 343.43 mm and 376.34 mm for artisanal and industrial fisheries, respectively. Using the Statistic 6.0 program, the t-test was applied between the average lengths of the two fishing fleets. It was estimated that there are no significant differences between these lengths (t = 1.65; stat t = - 22.72), accepting the null hypothesis: there is no difference between the average length of pyramutabas landed by the artisanal and industrial fleets. However, it is worth noting that the industrial fishery uses the pair trawl method, which is considered to be less selective than gillnetting and gillnetting, and that the measurements recorded for this type of fishery were all made in the industry and not on board the boats, where the specimens would be much shorter than those recorded, since this fleet discards many individuals because they do not yet have the necessary length for commercialization.