Experiments were carried out during two cruises in 1995 to test a prototype species-selective bottom trawl for separating cod from haddock and saithe, in the Norwegian bottom trawl fisheries in the Barents Sea. A sorting system incorporating a horizontal square mesh panel (150 mm bar length) dividing the trawl’s body and extension sections into upper and lower compartments, leading aft to verticallyoriented trouser codends, was installed in a commercial roundfish trawl. During the first cruise approximately 90% of the haddock and 70% of the saithe were caught in the upper codend, with 70% of the cod in the lower codend. During the second cruise 90% of the haddock and 60% of the saithe were caught in the upper codend, with 65% of the cod caught in the lower codend. In situ video observations showed that fish, apparently haddock, entered the trawl at all levels, but subsequently many of those in the lower half attacked upwards and through the separating panel along its length as they passed towards the trouser codends. The diVerences in the results by species and season are discussed, along with the applicability of the sorting system to commercial fisheries. ? 1998 International Council for the Exploration of the Sea