A system and method for sorting fish where the system comprises；&mdash；a trawl (2) consisting of at least one trawl bag (3, 3&prime；, 3&Prime；), and where the at least one trawl bag (3, 3&prime；, 3&Prime；) has an opening which covers a part of an inflow area in the trawl (2),&mdash；at least one monitoring device (6) arranged in connection with the inflow area and where signals can be transmitted to a processing unit from the at least one monitoring device (6), and&mdash；where a device, based on data from the processing unit, can move the opening in the at least one trawl bag (3, 3&prime；, 3&Prime；) to a position where fish flow through the inflow area but on the outside of the at least one trawl bag (3, 3&prime；, 3&Prime；).
