Hüseyin Özbilgin

Body shape and trawl cod end selectivity for nine commercial fish species

This study investigates the catch components of a commercially used demersal trawl cod end in Izmir Bay, and reveals some of the morphological characteristics of nine commercial fish species; red mullet ( Mullus barbatus ), hake ( Merluccius merluccius ), whiting ( Merlangius merlangus euxinus ), poor cod ( Trisopterus minutus capelanus ), tub gurnard ( Trigla lucerna ), common pandora ( Pagellus erythrinus ), axillary sea bream ( Pagellus acarne ), picarel ( Spicara smaris ) and annular sea bream ( Diplodus annularis ) in relation to mesh size and shapes. Furthermore selectivity of 40-mm polyethylene netting cod end for red mullet, hake, common pandora, axillary sea bream, picarel and annular sea bream is presented. The results are discussed in a way to understand the probable effects of fish body shape on mesh selectivity.

Marine debris in bottom trawl catches and their effects on the selectivity grids in the north eastern Mediterranean

In this study composition of marine debris and their blocking potential on the selectivity grid systems deployed on demersal trawls were investigated in the north eastern Mediterranean. For this, a total of 132 hauls were examined in two fishing season between 20 September 2010 and 19 February 2012. Results showed that plastic items were the most abundant debris (73% in terms of weight) and they were followed by metals (10%). Because of plastics and packing debris, it is highly probable that grids may have been blocked in 85% of trawl hauls. The bathymetric and geographical variability in the quantity of debris were evaluated, and concluded that particularly in some areas where direction of currents and bottom topography favor deposition, such devices may easily be rendered ineffective by the plastics and packing debris in particular. To solve this problem, several solution proposals are submitted.