PESCA SELETIVA DO TAMBIÚ, Astyanax bimaculatus LINNAEUS, 1758 (CHARACIFORMES, CHARACIDAE), COM A UTILIZAÇÃO DE REDES DE EMALHAR, NA REPRESA DE IBITINGA, RIO TIETÊ, ESTADO DE SÃO PAULO, BRASIL

The mean selectivity curve of gill-nets employed to cach "tambiu", Astyanax bimaculatus, in Ibitinga Reservoir, Tiete River, Sao Paulo State, Brazil, was determined according to Gulland (1969). The observed results are: c* (L) = e - 0.5207 (L-1.3478 m)2 Where: c* (L) = relative frequency of retention L = total length of the fish (cm) m = internal perimeter of the mesh (cm)   The interval of selection for different mesh sizes (m) is given by: Lm = mean L - 1.15 (cm)  and  LM = mean L + 1.15 (cm). The following relationships were also determined: - Total weight / total length of body: W = 0.0184 L 2.9685, where W = total weight of body (g) and L = total length of the fish (cm) - Fish perimeter (l) / mean fish total length relationship: l = 0.8299 L (cm) - Total lengths (and body weights) / internaI perimeter of meshes Since the females body length at the first sexual maturation is known (Lpm = 8.43 cm) in the reservoir, gill -nets with internaI perimeter major than 6.3 cm are recommended.