Essam Mohammed ¹ A.B.M. Mahfuzul Haque ² Md. Nahiduzzaman ^2*

• ¹ WorldFish (Malaysia), Penang, Malaysia
• ² WorldFish (Bangladesh), Dhaka, Bangladesh

The hilsa fishery, Bangladesh's largest single-species fishery, generates over USD 3 billion annually, 37 contributing 12% to annual fish production and supporting 2.5 million people. However, the growing 38 human population and the associated demand for fish protein have led to overfishing of both adult and 39 juvenile hilsa in the gill net fishery. In respons, the Department of Fisheries (DoF) and WorldFish 40 implemented the ECOFISH-BD project (2015-2019), funded by USAID, to promote sustainable 41 management practices. Despite the ecological and economic importance of hilsa shad (Tenualosa 42 ilisha), there is a significant gap in the literature regarding the economic evaluation of conservation 43initiatives. This study addrress that gap by examining the ECOFISH-BD project and assessing its 44 return on investment (ROI) in terms of ecological and socio-economic outcomes. The research 45 evaluates the historical context influencing hilsa production, assesses the project's impact on stock 46 recovery, and conducts a cost-benefit analysis to determine the ROI related to hilsa fishery 47 management and community livelihoods. Using the difference-in-difference method, the study 48 measured changes in income and assets, revealing a significant increase of 86.19% in income and 49 63.99% in overall assets in the intervention group compared to the baseline. Despite these positive 50 outcomes, challenges such as unequal benefit distribution, power imbalances in the hilsa value chain, 51 and the persistence of debt trap remain. While it is difficult to fully isolate the project's effects from 52 other external factors, the project has played a significant role in the recovery of hilsa stocks and the 53 subsequent increase in catch volumes. Furthermore, the project demonstrates strong economic 54 viability, evidenced by an internal rate of return of 32.8%. This study underscores the profitability and 55 investment potential of small-scale fisheries, challenging common misconceptions and advocating for 56 increased investment and institutional support to maximize long-term socio-economic and ecological 57 benefits.