Seasonal variation in mortality of red mullet (Mullus barbatus) escaping from codends of three different sizes in the Aegean Sea

Abstract

This study was performed off the southern coast of Yassica Island in the Izmir Bay on the Turkish coast of the Aegean Sea to investigate the mortality of red mullet (Mullus barbatus, Mullidae) escaping through 40-mm square-mesh and 44-and 50-mm diamond-mesh codends attached to a conventional demersal trawl net. In total, 48 replicate experimental hauls were performed in the summer and winter of 2011 and 2012. Mean escape mortality for all hauls in winter (33.2%+/- 6.51) was significantly higher (p<0.0001) than that in summer (26.5%+/- 6.19). Furthermore, mortality was also highest among the smallest fish, particularly during winter. Irrespective of season, the escape mortality of red mullet was lowest from the 40-mm square-mesh codend (mean, 25.5%+/- 4.58). These observations emphasize the importance of investigating the survival potential of escaping fish when considering the benefits of different selective devices in the management of a fishery.