Effects of Depth, Season and Mesh Size on the Catch and Discards of Whiting (Merlangius merlangus euxinus) Gillnet Fishery in the Southern Black Sea, Turkey

In this study, factors (depth, season and mesh size) influencing the catch and discards of whiting (Merlangius merlangus euxinus) gillnet fishery on the Black Sea coasts of Turkey were investigated. A total of 19 species were identified and the target species, whiting (Merlangius merlangus euxinus), dominated 87.56% of the total catch and followed by red mullet (Mullus barbatus) with 6.32%. While 82.02% of the total catch had commercial value, 17.98% was discarded. The percentage of the discarded red mullet and whiting under MLS (<13 cm) were found to be 16.03% and 13.27%, respectively. The highest discard amount was observed in winter and the lowest one in summer. The discard rate was highest in the 55-74 m depth group and the 32 mm mesh size. One-way analysis of similarity (ANOSIM) showed that there were significant differences in the discard species compositions between spring and summer, as well as 32 and 40 mm, 32 and 44 mm mesh sizes (P<0.05). These results on the discard information in gillnet fishery can contribute to the literature on ecosystem-based sustainable fisheries management by highlighting relevant results on the protection of species and ecosystem.