A comparison of size selection of haddock and whiting by square and diamond mesh codends

Abstract

When loaded with fish the codend of a fishing net is pulled into a bulbous shape. Fish escape mainly through the relatively small area of open meshes at the front of the bulb, and forward of this most of the meshes are stretched and closed. If the codend netting is hung so that the meshes are square they remain open during towing. Comparative fishing experiments withtrawls and seines to investigate the relative size selectivity of square and conventional diamond mesh codends for haddock and whiting are described. Several mesh sizes of each type were tested. It was found that the 50 % fish retention lengths for square mesh codends were larger than those for diamond mesh codends of the same nominal mesh size. For haddock, the selection ranges of square mesh codends on trawls were narrower than those of diamond mesh codends; on seines the ranges were similar. For whiting, the selection ranges of square and diamond mesh codends on trawls were similar but wider for square mesh codends on seines