مرکز منطقه ای اطلاع رساني علوم و فناوري - Comparison of the discard characteristics of diamond and square mesh codends in the Aegean Sea trawl fishery

Abstract :

The use of 40 mm square mesh codends was adopted in September 2008 as an alternative to the 44 mm diamond mesh codend in Turkish trawl fishery. In addition, European Commission suggests using this mesh shape and size codend in whole Mediterranean. For this reason this study is aimed to compare the discard characteristics of two different mesh shape also mesh size codends of demersal trawlers on the multi-species fishery in the Aegean Sea. Fishing trials were carried out on board a commercial trawler between 30 September and 25 October 2007 in the Sigacik and Kusadsi Bays of the Aegean Sea. By-catch as discarded catch plus incidental catch and discard ratio as the ratio of discard to the actual retained catch are defined and calculated. During the study, 21 valid trawl operations were performed, 53 species were caught and 11 of these species were retained on board. The discard ratio has been calculated as 0.42:1 for diamond (44 mm) and 0.25:1 for square (40 mm) mesh codend. The 30% and 20% of total catch was discarded respectively for diamond and square mesh codends, due to the lack of market value. The result of the study reveals that using square-meshed nets at the codend will reduce the amount of discards. Taking into account the specific characteristics of Mediterranean fisheries, it will be appropriate to put into practice additional technical measures such as mesh shape in order to ensure sustainable exploitation of fishery resources.