The Determination of Size Selection of Whiting {Merlangius merlangus euxinus) by Square Mesh Panel and Diamond Mesh Codends of Demersal Trawl in the Southern Part of Black Sea

摘要

The modification of the trawl codends to reduce the capture of juvenile fish increasing of fishing gear selectivity has been one of the management tools for sustainable fisheries. This study were examined the effect of square mesh escape panel installation on selectivity of demersal trawl codends for whiting (Merlangius merlangus euxinus, N.) in the Black Sea. Codend mesh selectivity experiments were carried out using 40 mm nominal diamond mesh PE codend with 36 mm and 40 mm mesh size square mesh escape window inserted in the forward part of the top panel. The experiments were carried out in the southern Black Sea between February and March 2006 on a traditional fishing boat. A total of 6 valid hauls were made by using the hooped covered codend method. Selectivity parameters were calculated by using a logistic equation with the maximum likelihood method. Mean L50s and selection ranges of whiting were determined as 12.57 (se. 0.41) cm and 3.45 (se. 0.03) cm for 40 mm nominal diamond mesh, 12.71 (se.0.45) cm and 3.12 (sc. 0.03) cm for 36 mm square mesh panel and 13.55 (se. 0.32) cm and 3.70 (se. 0.02) cm for 40 mm square mesh panel, respectively. The results shows that the use of square mesh panel (40 mm) in the forward part of the top panel reducethe capture of juvenile fish and increases the demersal trawl codend selectivity.