The device has vertical eyelets (2a) or rollers fixed at a horizontally braced metal wire (6) in a deep lying position. The wire is deflected towards an end of a longitudinal edge (7i) of nets (7). Each of the nets is gathered up in a bundle in a region of upper ends of supporting piles (1) by using an operating line (5). The operating line is movably guided in longitudinal directions (5b, 5c) by low-lying eyelets (2r) or rollers that are supported at upper ends of the piles. The operating line comprises a series of thin bolt-shaped lines (5a) that loops the nets, in a longitudinal extension.
