Development of a species-selective trawl for demersal gadoid fisheries

An experiment was carried out to test a prototype species-selective bottom trawl for separating cod from haddock, secondarily saithe, in the Norwegian commercial roundfish fisheries. 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 vertically-oriented trouser codends, was installed in a commercial roundfish trawl. First tests of the system, fishing around the clock, demonstrated approximately 90% haddock separation in to the upper codend, 71% cod separation in to the lower codend, and 72% saithe separation into the upper 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. Applicability of the sorting system to commercial fisheries is discussed