Review of studies on catch rates of commercial and bycatch species by hook type using in pelagic tuna longline fisheries

A large circle hook is known as one of the mitigation measures for sea turtles in the pelagic longline fisheries. The advantage and disadvantage of implementations of large circle hook to the longline have long been discussed. Numerous studies have been conducted on the effectiveness of the J hook and large circle hook on the catch rates for target and non-target species. However, the information such as the differences in effectiveness between J hook and Japanese tuna hook or between shallow-set and deep-set is still unclear. This document overviewed catch rates by three hook types for target and nontarget species reported in the published scientific papers and documents with the aim of organizing the existing information and clarification on the field which is lack of studies. Considering that lack of information about effect of Japanese tuna hook, effectiveness of large circle hook in deep-set and effect of large circle hook on catch rate of shark species, we recommend to consider SC14 that further research to evaluate the catch rates of target and non-target species especially sea turtles and sharks with using J hook, Japanese tuna hook, and large circle hook in deep-set longline should be needed to reduce the uncertainties of effectiveness for them by the implement of large circle hook.