3 SEINE NETS SAMPLING APPLIED TO THE LITTORAL-ZONE OF 2 BRAZILIAN TROPICAL RIVERS WITH REDUCED VELOCITY (BRAZIL)

Three seine nets (TSN method) laid simultaneously from the bank to for m concentric semicircles (enclosing an area of 350 m(2)) and hauled on e after the other were employed for the removal fishing technique in L ittoral zones with reduced velocity in the Parana River catchment. Fis h density was estimated using the Zippin maximum likelihood method. Th e efficiency of this TSN method, estimated by two different indexes wa s not diminished by the size of the populations, but was limited by th e kind and amount of obstacles on the bottom (submerged macrophytes, b ranches, mud) and the habitat preferences of the fish taxa. TSN was fo und to give best results for pelagic fishes, slightly less good for be ntho-pelagic, and less good again for benthic ones, although it was no t altogether unsatisfactory for quantitative research on fish populati ons. (C) 1997 Elsevier Science B.V.