WOS: 000186567400002This study investigates the differences of selectivity between a plain codend (C) and a codend surrounded with a protective bag (CP). The experiments were carried out in the Bay of Izmir in the Eastern Aegean Sea between 16 January and 14 February 2002. The experiments were conducted onboard the RN Egesuf (27 in loa, 500 hp main engine) by employing a conventional bottom trawl commercially used in Turkish waters. The hooped covered codend method was used to obtain selectivity data. Eleven valid hauls (45 min towing duration and 2.5 knot average towing speed, 25 to 30 to water depth) were carried out both with C and CP Data were collected for red mullet (Mullus barbatus), annular sea bream (Diplodus annularis), picarel (Spicara smaris), and common pandora (Pagellus erythrinus). Selectivity parameters were obtained by using a logistic equation with the "Maximum Likelihood Method". Selectivity of C and CP was found to be very similar for the species investigated except that the 50% retention length (L-50) of CP was 9% higher than that of C for common pandora, and the selection range (SR) of CP was 32% wider than that of C for picarel. L-50 values obtained for C and CP were 10.7 and 10.6 cm for red mullet, 8.6 and 8.6 cm for annular sea bream, 12.3 and 12.1 cm for picarel, and 10.3 and 11.2 cm for common pandora, respectively. These results show that the protective bags used in Turkish demersal trawling do not have a significant effect on codend selectivity for the species investigated. The codend tested here and commercially used in Turkish waters retains a significant number of immature fish and therefore needs to be modified in order to improve its selectivity
