Effect of offset hooks on catching efficiency and hooking positions of carangids, evidence from the Gulf of Mannar, India

Abstract

The efficiency of different shapes of J hooks number 8 (non-offset straight hook, 10° offset kirbed hook, and 10° offset reversed hook) in Carangids longline fishing gears was studied in 15 fishing grounds in the Gulf of Mannar, India, from April to August 2022. For the comparative study, a total of 15 fishing trips were conducted for each experimental gear with a total effort of 6,750 hooks, resulting in a total catch of 176 fishes during the study. Amidst the hook shapes, the kirbed hook had the highest percentage composition of the carangids (43.75 %), followed by the reversed hook (30.68 %), and the straight hook (25.57 %). Furthermore, the overall hooking rate was higher for the kirbed hook than for the straight hook (5.1 % vs. 3 %). Considering the catch rate, the overall Catch Per Unit Effort (CPUE; individual/150 hooks) of the kirbed hook was higher (6.4 vs. 3.75) than that of the straight hook. The percentage of hooking position in the jaw was higher in the kirbed hook than that of the straight hook (55.84 % vs. 37.78 %) and was found to be lower in the gut system (14.29 % vs. 28.89 %). Among the three hook shapes tested, the overall performance of the 10° offset kirbed hook was found to be better than the other 10° offset reversed and non-offset J hook in terms of a catch efficiency, hooking rate, CPUE, and hooking position for carangids (< 0.05).