Selectivity experiments with square mesh codends in bottom trawl

Abstract

During selectivity experiments with square and diamond mesh codends, an evaluation of the covered codend method and a modified trouser trawl method went in favour of the last one. Both twisted knotless- and braided knotted material was used for the experiments. Square mesh codends gave higher 50% retention lengths and selection factor than the diamond mesh codend, both for cod and haddock. Fished commercially, the square mesh codend of knotted netting caught fewer undersized fish than the diamond mesh codend. Big bycatches of redfish caused heavy meshing in the square mesh codend and reduced the selectivity. Due to the fixed circumference of the square mesh codend some problems arose when emptying big hauls on a sterntrawler.