Selectivity parameters of European hake gillnets for target and by-catch species with a perspective on small-scale fisheries management in the Sea of Marmara, Turkey

Abstract This study aims to describe the selectivity features of European hake gillnet for Merluccius merluccius (European hake, target species) and Solea solea (common sole, by-catch species) in the southern Sea of Marmara in terms of small-scale fisheries. For this purpose, the size selectivity of gillnets for European hake and the common sole was studied in the Sea of Marmara. Experimental fishing operations were carried out by using gillnets with a mesh size of 28, 30 and 32 mm. A total of 523 specimens of European hake and 418 specimens of common sole were caught. Total lengths ranging from 23.5 to 41 cm were recorded for European hake and from 18.5 to 35.5 cm for the common sole. The experimental data estimated by applying the SELECT method showed that the bi-modal and log normal models gave the best fit for European hake and the common sole selectivity, respectively. Estimated modal lengths were found to be 30.61; 32.80; 34.99 cm for European hake and 19.94; 21.37; 22.79 cm for common sole for each mesh size studied. The present study is the first report on the selectivity of these species using the SELECT method for European hake gillnets in Turkey. The results obtained from the present study show 30 mm mesh size which is used currently by fishermen is highly selective and very suitable for sustainable fisheries both European hake and common sole. These findings will help to improve the management and conservation of small-scale fishery, especially, in this region.