Determining the hook selectivity of bottom longline used for European hake (Merluccius merluccius, L. 1758) in Saros Bay (northern Aegean Sea, Turkey)

Abstract

This study was carried out at Saros Bay, between June 2011 and July 2013 to determine hook selectivity of bottom longlines used on European hake (Merluccius merluccius, L. 1758) fishing. Throughout the study thick type in 6, 7, 8 and 9 sized flat hooks were used between 150 to 400 m depth. 36 fishing operations were carried out and 222 fish were caught by using 7200 hooks in total. Depending on the size of hooks number 8 was the most efficient hook that has caught 114 fish and number 6 was the least efficient one that has caught only 14 fish. The SELECT method is used in the determination of the selectivity parameters. Bi model has given the best fit according to selectivity analysis of five different models. Optimum catching lengths were found 60.09 cm for 6 number hook 51.45 cm for 7 number hook 46.43 cm for 8 number hook 40.11 cm for 9 number hook, respectively in Bi Model model. Minimum size limit for European hake is 25 cm in Turkey. Considering the minimum size limit, use of hooks with gapes larger than number 9 hook (11.75 mm) used in this study is suggested.