The Effect of the Live Bait Type and Hook Size on the Catch Per Unit Effort and Catch Composition of Seabass, Dicentrarchus labrax (L.,1758) in Longline Fisheries

The main objective of the study, was to determine the effect of the live bait type and hook size on the catch per effort and catch composition of seabass, Dicentrarchus labrax (Linnaeus, 1758) in longline fisheries. Live Mediterranean sand eel, blotched picarel and flathead grey mullet were used as baits together with 3/0, 4/0 and 5/0 J type fishing hooks. This study was carried out between March 2020 and April 2021 in the Çanakkale Strait, Turkey. The main body line thickness was 0.70 mm and snoods having a line thickness of 0.50 mm and length of 2 m were tied at 6 m intervals. The fishing time covered the period from sunset to early hours of the sun rise. In all trials, a total of 263 seabass were caught which consisted 84% of total catch followed by 42 individuals of European conger Conger conger, a non-target species, corresponding to a catch rate of 13.3%. A total of 314 fish were caught by longlines and the catch yields with respect to hook size were 149 fish with 3/0 hook, 91 fish with 4/0 hook and 74 fish with 5/0 hook. The highest and lowest numbers of non-target fish species were caught with hook size 3/0 and 5/0, respectively. Hook sizes smaller than 3/0 should not be used in seabass longline fishing to prevent excessive catch of smaller fish. Blotched picarel, Spicara maena proved to be a superior live bait than flathead grey mullet, Mugil cephalus the Mediterranean sand eel Gymnammodytes cicerelus.