Fish Morphology and Barrier Trap Bar Spacing in Lagoon Fisheries along the Aegean Coast of Turkey

The most important fishing rule implemented in Turkish lagoon fishery is distance between the reeds (stick) of the barrier traps should not be less than 3 cm. Based on this arrangement, usually 3 cm bar spacing reeds and sometimes 3 cm square mesh wires are used in lagoon barrier traps. The body shape of fish may be the most important factor necessary to understand the consequences of changes in barrier trap selectivity. For this reason, data were collected to determine the relevant dimensions of fish body in relation to openness of a barrier trap of coastal lagoons along the Aegean coast of Turkey in 2013. As Minimum Landing Size (MLS) was built on Total Length (TL) basis, regression analyses were carried out to find out the relationships between the TL and the other measured dimensions (width and height) of the fish using least-square regression. Morphometric measurements of fish species caught in barrier traps show a great variation. While all Common sole individuals pass from the 3 distance with its width, all Flathead grey mullet and European sea bass individuals retained behind the sticks of the barrier trap. All Gilthead sea bream individuals under 25 cm TL pass the distance. However, many Golden grey mullet and European eel individuals retain at the barrier traps with theirs width. The implemented 3 cm bar spacing in Turkish lagoon barrier traps is thought to be suitable only for sea bass with a 1% reduction. However, the bar spacing is not suitable for Sea bream, Common sole, European eel due to commercial loss and for Flat head grey mullet and Golden grey mullet capturing small individuals below their MLS. For this reason, a graded barrier system with different bar spaces or regulation according to the biology of the fish species and migration seasons can benefit sustainable lagoon fishery. In this respect, the continuously changing distance paradox in barrier traps will be overtaken in Turkey.