The Effect of Twine Thickness of Monofilament Gillnets on the Catchability and Fishing Gear Losses For Pikeperch (Sander Lucioperca (L., 1758)) Fishing

In this study, the effect of twine thicknesses on the catch efficiency in monofilament gillnets were investigated. Field trials were carried out in Seyhan Dam Lake between September 2020 and September 2021 on a monthly basis. Net codes with different mesh sizes (bar length) and twine thicknesses were as follows, respectively: 1=26 mm 0.16 mm, 2=26 mm 0.18 mm, 3=28 mm 0.16 mm, 4=28 mm 0.20 mm, 5=30 mm 0.16 mm, 6=30 mm 0.20 mm, 7=30 mm 0.33 mm, 8=32 mm 0.16 mm, 9=32 mm 0.20 mm. A total of 34 experimental fishing operations were carried out. The results showed no statistically significant difference between the catch efficiency of thin twine and thick twine in nets with 26 mm and 32 mm mesh sizes (p>0.05). However, significant differences were found in the 28 mm mesh size (p<0.05). In gillnet with 30 mm mesh size, no statistical differences were observed in catch efficiency between net codes 5 and 6 (p> 0.05). However, statistical differences were found in catch efficiency between net codes 5 and 7, as well as between codes 6 and 7 (p <0.05). These results indicate that a 12.5% (twine thickness: 0.16-0.18 mm) and 25% (twine thickness:0.16-0.20 mm) increase in rope thickness did not affect catch yield, whereas a 65% (twine thickness: 0.20-0.33 mm) increase did..