M.Hakan KAYKAÇ, Mustafa ZENGİN, Zafer TOSUNOĞLU

Can Shifting Codend Mesh Shape and Mesh Size Increase the Size Selectivity of Red mullet (Mullus barbatus) in the Black Sea?

More than half of the landing (70%) of Red mullet (Mullus barbatus) in Turkey is provided from the Black Sea, whichis almost all (96%) with bottom trawls. The effect of demersal trawl codend mesh shape and size on the s electivity of Redmullet in the Black Sea was investigated. Selectivity trials were conducted in August 2014 on a commercial trawl boat withconventional (40D), 36 and 40 mm square mesh (36S and 40S) and turned mesh codends (40T90). Data were collected usingthe covered codend method with a total of 21 valid hauls and selection parameters were obtained by fitting a logistic equationusing maximum likelihood method. The $L_{50}$ value was found to be very low at 9.79 cm in the 40D trawl codend, while the $L_{50}$value of 40S (11.89 cm) and 36S (10.59 cm) codends was obtained 21.5% and 8.2% better compared to the 40D, respectively.According to the traditional trawl codend, a $L_{50}$ value increase of 5.1% was observed in 40T90 (10.29 cm). Although all thesevalues are below the Minimum Landing Size of the species, changes to the traditional mesh, especially in the shape of themesh, can lead to significant improvements in size selectivity.

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