Selective catching of "Viuvinha" Moenkhausia intermedia Eigenmann, 1908 (Characiformes, Characidae), by employng monofilament Gill-nets, in Ibitinga Reservoir, Tietê River, São Paulo State, Brazil

Abstract

It was determined the mean selectivity curve of gill-nets utilized in the catching of the fresh-water fish "viuvinha", Moenkhausia intermedia Eigenmann, 1908, in Ibitinga Reservoir, Tietê River, São Paulo State, Brazil, through the model proposed by GULLAND ( 1971). The observed results are:

c* (L) = e ^{-1.06 (L -1.55 m)2}

where:

c* (L) =relative frequency of retention

L = total length of the fish

m = internal perimeter of the mesh

The interval of selection for different mesh sizes

(m) is given by:

L_m= í  0.81(cm) and L_M= + 0.81 (cm)

Total length relationships both to body weight and internal perimeter of mesh were also determined. The females body length in the first sexual maturation period was done by Lpm = 8.50 cm. Since the females body length in the first sexual maturation is known in the reservoir, gill-nets with internal perimeter major than 5.00 cm are recommended.