Background. Bottom trawling is an important fishing technique for catching demersal fish, and selectivity is one of the most important tools for fishery management. This study aimed to determine the selectivity of 40 mm square- (40S) and 90º turned-mesh (40T90) codend for the deepwater rose shrimp, Parapenaeus longirostris, and greater forkbeard, Phycis blennoides (Brünnich, 1768). Materials and methods. Fishing experiments were conducted on the international waters of the Aegean Sea by using a commercial vessel between 24 August and 13 September 2012. The hooped covered codend technique was employed for the estimated codend selectivity. The selectivity parameters were estimated by using CC 2000 software. Results. Nineteen successful hauls, 11 with 40S, and 8 with 40T90 codends, were performed. The mean L50 values (50% retention length) of 40S and 40T90 were found to be a 15.5 ± 0.1 mm and 14.8 ± 0.1 mm carapace lengths for the rose shrimp, and 15.3 ± 0.1 cm and 12.2 ± 0.1 cm total lengths for the greater forkbeard, respectively. Conclusion. In conclusion, 165 square meshes in a codend circumference with 40 mm mesh sizes provided higher L50 values than the 40 mm turned meshes, and 330 meshes around the codend circumference.  Halving the number of meshes in the codend with larger turned mesh and different modifications should be investigated for further studies in order to appropriate the L50 values.

bottom trawl, responsible fisheries, size selectivity, mesh type