(Selectivity curve of gillnets utilized in catching, "saguiru" Curimata elegans Steindachner, 1875 (Osteichthyes, Curimatidae), in Bariri Reservoir, Tietê River, São Paulo State, Brazil)

Abstract

The purpose of this work was to determine the selectivity curve of gill-nets utilized for catching "saguiru", Curimata elegans Steindachner, 1875, in Bariri Reservoir, Tietê River, São Paulo State, Brazil, through the model proposed by Gulland (1969). The observed results are:

c*(L) = e-^{0,1042 (L - 1,795 m)²}

Where: c*(L) = relative frequency of retention

                     L = total Iength of the fish

                    m = internal perimeter of the mesh.

The interval of selection for different mesh sizes (m) is given by:

L_M = 1.7954 m + 2.58 (cm)

L_m = 1.7954 m í  2.58 (cm).

Were also determined the relationships between total body weights and the internal perimeter of meshes, through the relation:

W = 0,0236 L^2,8202

Where: W = total weight of body (g)

               L = total length of the fish (cm).