By-catch ratios from the bogue (Boops boops) gillnet fishery around the sea-cage fish farms in Güllük Bay (Aegean Sea)

This study aims to reveal the by-catch rates for gillnet fishery, targeted Boops boops by small-scale fisheries around fish farms in Güllük Bay (Aegean Sea), and to determine the by-catch per unit effort (BPUE) rates. The study was carried out through deck sampling at Göltürkbükü, Gündoğan, Yalıkavak, and Torba fishing ports during two seasons between November and April (2017-2018 / 2018-2019). A total of 147 fishing operations from 13 boats were randomly monitored. In gillnet fishing for bogue, a total of 18163 kg of the catch was caught from 48 species belonging to 30 families, including invertebrates. The target Boops boops was the most common species with a rate of 91.9%, of which 8.1% was determined as a by-catch. The most caught by-catch species are Diplodus annularis (Linnaeus, 1758), Scomber colias (Gmelin, 1789), Trachurus trachurus (Linnaeus, 1758), Pagellus acarne (Risso, 1827), Scomber scombrus (Linnaeus, 1758). While the average BPUE was 4.77 ± 0.85 kg.1000 m-1 in 2018, it was 3.20 ± 0.58 kg.1000 m-1 in 2019. November gives the highest average in terms of BPUE values. The average BPUE ranged from 0 to 19.1 kg.1000 m-1 (mean: 7.97 ± 2.83 kg.1000 m-1). Statistically, there is a significant difference in BPUE values between the months (Kruskal-Wallis test, p < 0.05).