Skirts permanently installed in fish farms appear to halve the number of salmon lice. Before Easter researchers at SINTEF Fisheries and Aquaculture ran model tests in a flume tank at the laboratory in Hirtshals to examine net deformation and water currents in and around a net pen. For example, would strong currents render the skirt useless? And would the presence of the skirt entail greater stresses on the net pen moorings? The tests demonstrated that the stresses on the moorings of a coarse-mesh net pen increased by just under 40%, while there were no major variations in the forces acting on the moorings during tests with skirts extending to different depths.