Selectivity of trammel nets (80 ve 90 mm mesh size) for common sole (Solea solea linnaeus, 1758) used in Güllük Bay

This study was aimed to determine the selectivity parameters of sole trammel nets which are used in Gulluk Bay which is one of the important fishing grounds in Turkey. Samplings were realized between November 2013 - December 2015 with trammel nets stretched mesh size with 80 and 90 mm. In total, 1209 samples were caught. SELECT method was used to determine the selectivity parameters. Bi-modal the best fitted the data. Optimum lengths for 80 and 90 mm trammel nets were found as 23.20 and 27.02 cm, respectively. Also, for 80 and 90 mm trammel nets, lengths at first capture values (Lc) were estimated as 20.37 and 24.11 cm and CPUE values were calculated as 2.94 and 1.43 kg/1000m, respectively. As it seen from CPUE values, fishing pressure effects large-sized individuals. This situation means decreasing in spawning stock biomass and the number of small-sized individuals that provide continuance of generations, will be less than now when considered natural and fishery mortalities. In commercial fishery laws, size limitation for common sole is 20 cm. Lengths at first capture values are too close to limitation. So, there is no need for any application toward mesh size regulation but a serious regulation is needed on the number of trammel net panels.