Selectivity of fishing gears like trawls is obviously conditioned by the fish behaviour but also by the net and the flow. As well, flow may affect fish behaviour. With the aim of a better understanding of the flow in presence of a net and a catch, we suggest, through the experimental study below, to determine and to analyze the flow over a rigid cod-end in two configurations: with a closed and an open net entrance. Trials took place in a free surface flume tank and the flow characteristics were determined from velocity measurements obtained by laser velocimetry (inside, outside and through the meshes of the stiff cod-end). The experimental device, the measures and their analyzes are given here.