Comparison of catch and length compositions of deep water cast nets designed with different mesh sizes used in whiting fisheries in the Eastern Black Sea

Whiting "Merlangius merlangus (L. 1758)" is among the bottom fish of commercial importance in the Eastern Black Sea and the stock is under constant pressure with different fishing gear throughout the year. In the Eastern Black Sea Region where trawl fishing is prohibited, whiting fishing is carried out by using bottom gillnets and cast nets. In this study, fishing yields of deep water cast nets having different mesh size were compared. The study was carried out in Rize - Gündoğdu offshore in July and August 2018. 66 fishing operations were performed for each of the cast nets having an arm length of 8, 10, 12, 14, 16 mm. As a result of the study, a total of 168.35 kg whiting was fished. No fish or crustaceans were found in the catch composition except for the target species whiting. The cast net with an arm length of 10 mm was the most efficient and fished an average of 824 gr fish per operation. In the 16 mm cast nets, individuals below 13 cm, which is the minimum fishing length, constitute 1% of the total catch amount. In commercially used cast nets that have a mesh arm length of 8 mm, the amount of fish caught under 13 cm is 88% of the total product. In the light of the data obtained from this study, 16 mm mesh arm size is recommended for the commercial deep water cast nets.