Size selectivity of sole gill nets fished in the North Sea

The size selectivity of sole nets was measured indirectly on a Danish commercial gill net vessel in the North Sea by using nets made in seven different mesh sizes fished simultaneously. Maximum likelihood procedure was used to fit different forms for the selection curve to the catch data for sole, plaice and cod for each setting of the gear. It was found that a hi-normal form for the selection curve gave the best fits. Mean selection curves were then estimated by combining sets using a model of between-set variation. The ratio between length of maximum retention and mesh size was estimated to be 3.28 for sole, 2.60 for plaice and 4.56 for cod. Selection curves were also fitted to the catch data pooled over all sets. The model deviance for the sole and plaice data indicated lack of lit when pooling the catch data. (C) 1999 Elsevier Science B.V. All rights reserved.