Estimating blue marlin (Makaira nigricans) sustainable yield in the Indian Ocean using a data-poor approach

Abstract

Blue marlin (Makaira nigricans) is a common bycatch species in the global tuna longline fishery. In this study, we applied a common data-poor approach, i.e., depletion-corrected average catch (DCAC) to assess stock status of the Indian Ocean blue marlin. Sustainable yield (Ysust), one reference point in this case, was estimated, and its uncertainty was integrated by using Monte Carlo simulation. The results revealed the estimate of Ysust by DCAC was lower than MSY of 11,926 t by BSP-SS and is also lower than the provisional reference point of 11,704 t by the management proposal. DCAC is reliable for blue marlin in driving precautionary management quantity based on the CPUE of Japan (1980–2015). This study also implies that DCAC could be applied to other billfish stocks and uncertainty be estimated for sustainable yield. However, data-poor methods could be adjusted with precautionary approaches.