Review on the effect of hook type on the catchability, hooking location, and post-capture mortality of the shortfin mako, Isurus oxyrinchus
Due to the assessed vulnerability for the North Atlantic shortfin mako, Isurus oxyrinchus, ICCAT has identified the need to better understand the use of circle hooks as a potential mitigation measure in longline fisheries. We conducted a literature review related to the effect of hook type on the catchability, anatomical hooking location, and post-capture mortality of this species. We found twenty eight papers related to these topics, yet many were limited in interpretation due to small sample sizes and lack of statistical analysis. In regards to catchability, our results were inconclusive, suggesting no clear trend in catch rates by hook type. The use of circle hooks was shown to either decrease or have no effect on at-haulback mortality. Three papers documented post-release mortality, ranging from 23-31%. The use of circle hooks significantly increased the likelihood of mouth hooking, which is associated with lower rates of post-release mortality. Overall, our review suggests minimal differences in catchability of shortfin mako between hook types, but suggests that use of circle hooks likely results in higher post-release survival that may assist population recovery efforts.