Equipment modifications to reduce mortality in bottom longline: Comparison of common (J type) and alternative circle (C type) hook performance

In this study, performance comparisons were made with the C type hook used as an alternative to the conventional used J type hook in order to reduce the injury and mortality rates in bottom longline. Based on the data obtained two different hook types, injury damage rates depending on where they are hooking to the fish body, survival index, target and discard, elasmobranch and teleost fish were compared according to hook type. During the research 21 valid bottom longline studies were performed. There was no significant result between the two types of hook in hunting efficiency comparisons (p> 0.005). It was determined that the fish caught in C type hooks had lower injury rates than those caught in J type hooks. For this reason the survival index of fish caught in type C hooks were higher (p<0,005). Injuries caused by the fish caught in the deep hooking area were more damaged than the ones caught by the shallow hooking (p<0.005), there was no statistically significant difference between the mean length of the fish caught according to the hooking area (p> 0.005).