Examining the emerging quota transfer system for Japanese Pacific bluefin tuna fisheries through social network analysis

This study examined the characteristics and effects of the quota transfer system implemented in the Japanese Pacific bluefin (PBF) tuna Thunnus orientalis fisheries. Social network analysis revealed that from fishing year (FY) 2018 to FY2021, the number of management units involved in quota transfer increased, the network became denser, and approximately half of the transfer pairs were maintained in the following year. The results of network structure analysis, including triad census and block modeling, showed that some management units (e.g., minister-managed purse seines, Ishikawa prefecture) play an important role in facilitating unilateral transfers and virtually mediate transfers between other units. A brief analysis using initial/final quota and catch data suggested that while the system helped with quota compliance and contributed to effective quota use, there was little evidence that quota allocation or catch was significantly concentrated after the introduction of the quota transfer system. These findings suggest that quota transfers could be further promoted by: (1) sharing up-to-date information on quota use and transfer networks; (2) providing highly accurate forecasts of sea conditions and PBF arrival; (3) semi-automating the matching and approval process; (4) encouraging multi-level quota transfers; and (5) creating more incentives for transferors.