|Discards in the sole fishery has been a problem for several decades due to the small mesh size in the cod-end of the trawl. This is reflected in the discarding many species of which plaice belongs to that species in which the highest proportion of discards is found. A catch separation during the capture process is the best option for the survival of these often unwanted bycatch.
Separation of two flatfish species in a trawl is usually difficult because of the similar behavior. Sole and plaice differ quite strong in physical appearance and especially in stiffness of the body and sole has a stronger tendency to dive. This opens possibilities for catch separation with a horizontal separator panel. Preliminary tests with such a panel showed potential.
The test gear is the beam trawl. In this trawl, a separator panel is fitted to experimentally determine the extent to which sole and plaice can be separated. Since this experiment is still in an early stage, day trips are ideal. As such, after a brief experiment at sea, the necessary adjustments to the net can be made.
To investigate the separating capacity of the panel, the net is equipped with two cod-ends, one that collects the catch which is derived under the panel, and a second one that collects he catch which is guided above the panel. Of all commercial fish species in the catch, the length frequency is determined. For non-commercial fish and invertebrates, the volume is to be determined.|