Appropriate reference points for WCPO elasmobranchs. Report to the Western and Central Pacific Fisheries Commission

Three closely related projects on pelagic elasmobranchs in the Western and Central Pacific Ocean (WCPO) have been conducted in recent years. The first was a thorough review of appropriate limit reference points (LRPs) which was completed in 2014 (Clarke and Hoyle, 2014). This study recommended a tiered framework, similar to that adopted for target species, for defining LRPs for elasmobranch bycatch. Since most elasmobranchs are data-poor stocks, the study strongly suggested that quantitative ecological risk assessments (ERA), also called risk-based approaches, be used for defining LRPs. As ERAs require many life-history parameters (LHPs), the study also identified the collation of information on LHPs as a priority issue, which led to a second project that compiled a comprehensive LHP dataset and produced a report (Clarke et al., 2015). Using this dataset and some additional data from literature, a third project derived risk-based reference points for 15 elasmobranch stocks (Zhou et al. 2019). SC15 recommended that the key conclusions from Zhou et al. (2019) be summarized together with any other relevant information.
In this current report, we summarize major sections from Zhou et al. (2019). Core elements include: estimating F-based reference points; potential methods for estimating fishing mortality; other potential management procedures for WCPFC elasmobranchs; and a review of shark stock-recruitment relationships. Among these four major sections, “estimating F-based reference points” is the most relevant to the current project and is the focus in the current study...