Bio-economic trends of Hilsa (Tenualosa ilisha) fishery: Perspectives of transboundary management between India and Bangladesh

Hilsa (Tenualosa ilisha), the choicest table fish of Indian subcontinent, provides livelihood for 2.5 million fishermen of Bangladesh and 0.46 million fishermen of West Bengal (WB), India. Hilsa fishery contributes around 1% to the GDP of Bangladesh. Years of over-exploitation of Hilsa fishery through open access has led to an unprecedented decline in Hilsa stock in recent decades. The study aims to investigate the economic efficiency and existing management practices of Hilsa fisheries of WB (India) and Bangladesh. The Gordon-Schafer surplus production model was used to derive a deterministic bio-economic model on Hilsa fishery from the catch-effort-cost-price data of WB (India) and Bangladesh collected between 2002 and 2015. Hilsa populations of two countries have a similar growth rate (r = 0.224). Hilsa catchability coefficient (q) of Bangladesh is 0.000003553, which is about 20 times lower than WB (India) where it is 0.00007147. Fishing effort and Hilsa yield are not significantly associated with each other in WB (India) but in Bangladesh fishing effort has significant positive impact on Hilsa yield. If effort is increased by 1%, the yield in WB (India) may decrease by 1.12% whereas in Bangladesh the same may increase by 8.48%. Results indicate variable habitat conditions and biology of Hilsa are possibly more important for Hilsa yield of Bangladesh compared to WB (India). A 10-20% discount rate is sustainable option for Hilsa fisheries of WB (India) and Bangladesh. The stock reduction analysis demonstrates that WB (India) stock is severely overfished while Bangladesh stock exhibits stability in the overfishing zone. A trans-boundary management of Hilsa fishery is recommended which includes forming a joint scientific council, joint monitoring and facilitating data availability, imposing similar discount rates, ban periods, mesh sizes, and introduction of effort and landing taxes.