Some biological-fishing aspects in the catching of "pescada- cambucu", Cynoscion virescens Cuvier, 1830 (Percoidei, Scianidae) by gill-nets in the São Paulo State coast, Brazil

Abstract

The main objective of this work was to determine the mean selectivity curve of gill-nets with the perimeter of 12, 14, 16 and 18 cm utilized for catching "pescada-cambucu", Cynoscion virescens, in the São Paulo State coast, through the model proposed by Gulland (1971). The results indicate that the mean selectivity of these nets can be represented by:

C*(L = e^{-0.0092(L-1.9786 m)2}, where de interval of selection for different mesh sizes (m) is given by:

L_M = 1.9786 m + 8.68 (cm)

L_m = 1.9786 m í  8.68 (cm)

The data permitted also to conclude that most fishes are retained in the post opercular length (61.47%). The coefficient K used to determine the optimum mesh size was calculated according to Baranov, quoted by Andreev (1966) and found to be 0.13. It was also determined the optimum mesh size for catching, 40 mm or over (mesh = bar) for prevent capturing immature individuals and maximum yield in commercial size of this species.