Bioeconomic Management of Mackerel Tuna (Euthynnus affinis) in Tulungagung Regency: Evaluating MSY, MEY, and Open Access Regimes

The species Euthynnus affinis has been reported as a dominant catch in Tulungagung Regency, comprising an average of 36 percent of total landings between 2017 and 2023. Despite its abundance, the fishery is identified as fully exploited and inefficiently managed. This study provided the first application of the Fox surplus production model in the region to analyze the bioeconomic performance of Euthynnus affinis fisheries under three management regimes: Maximum Sustainable Yield (MSY), Maximum Economic Yield (MEY), and Open Access (OA). Both biological and economic parameters were assessed using primary and secondary data. The analysis revealed that actual catches remain below the MSY level, indicating that biological overfishing has not occurred. The MEY regime produced the highest economic rent with minimal fishing effort, demonstrating the most economically efficient and sustainable option. In contrast, the OA regime resulted in zero rent and excessive fishing effort. Dynamic optimization analysis using a 10% discount rate was employed to simulate long-term profitability under different management scenarios. The findings support the establishment of MEY-based policies, including fishing effort limits and quota allocations, and provide evidence-based recommendations to enhance the sustainability and economic viability of tuna fisheries in Tulungagung Regency.