Effect of Square Mesh Escape Window on Codend Selectivity for Three Fish Species in the Aegean Sea

Authors: CENGİZ METİN, HÜSEYİN ÖZBİLGİN, ZAFER TOSUNOĞLU, GÖKHAN GÖKÇE, CELALETTİN AYDIN, GÜLNUR METİN, ALİ ULAŞ, HAKAN KAYKAÇ, ALTAN LÖK, F. OZAN DÜZBASTILAR, ADNAN TOKAÇ

Abstract: Poor selectivity of conventional trawl codends has recently been a serious concern in Turkish fisheries. Modification of the codends to reduce the capture of juvenile fish has been one of the management tools for sustainable fisheries. This study investigates effect of square mesh escape window installation on selectivity of bottom trawl codends for red mullet (Mullus barbatus), annular sea bream (Diplodus annularis) and common pandora (Pagellus erythrinus) in the Aegean Sea. Codend mesh selectivity experiments were carried out using 40 mm nominal diamond mesh PE codend with a square mesh escape window inserted in the forward part of the top panel. The experiments were carried out in İzmir Bay in the eastern Aegean Sea between 24^{th} June and 31^{st} July 2002 on board R/V "Egesüf". A total of 9 valid hauls were made by using hooped covered codend method. Selectivity parameters were obtained by using logistic equation with the maximum likelihood method. Mean L_{50}s and selection ranges of the window installed codend were found as 12.55 (se 0.18) and 2.27 (se 0.06) cm for red mullet, 9.49 (se. 0.27) and 1.26 (se. 0.05) cm for annular sea bream and 12.18 (se 0.31) and 2.00 (se 0.07) cm for common pandora, respectively. Comparison of the results with those obtained in other studies carried out in the same area by using conventional codends show that the use of square mesh escape window in the forward part of the top panel increases the escape of juvenile red mullet, annular sea bream and common pandora.

Keywords: Aegean Sea, mesh selectivity, square mesh, trawl escape window, Mullus barbatus, Diplodus annularis, Pagellus erythrinus

Full Text: PDF