Theoretical Framework for Valuing Ecosystem Services of Nigerian Freshwater Fisheries for Policy Integration

The chronic undervaluation of ecosystem services provided by Nigerian freshwater fisheries in government policy frameworks has resulted in their systematic subordination to extractive interests, yet no comprehensive theoretical framework for ecosystem service valuation calibrated to Nigeria's inland fisheries systems has been developed. This study develops an original theoretical framework for the total economic valuation of ecosystem services provided by Nigerian freshwater fisheries, applying and extending the Millennium Ecosystem Assessment ecosystem services typology to the specific biological, social, and institutional context of Nigerian inland waters. The framework integrates provisioning service values (food fish and aquaculture water supply), regulating service values (water purification, flood attenuation, and carbon storage), cultural service values (recreation, spiritual, and aesthetic), and supporting service values (nutrient cycling and biodiversity maintenance) into a coherent total economic value accounting structure. Original contributions include the development of a participatory valuation protocol for capturing spiritual and cultural service values of water bodies in communities with traditional beliefs relating to fisheries, and a non-market valuation approach for biodiversity maintenance services adapted to data-scarce contexts. The framework was applied to three case study water bodies in Anambra, Niger, and Kogi States using a mixed portfolio of valuation methods including contingent valuation, benefit transfer, and production function approaches. Total economic values ranged from 1.8 to 4.2 billion Naira per year across the three water bodies, substantially exceeding official government estimates of the economic importance of these fisheries. The study provides a theoretically grounded valuation framework for lobbying for improved fiscal and policy treatment of freshwater fisheries in Nigerian national development planning.

Keywords: ecosystem services valuation, freshwater fisheries, total economic value, policy integration, Nigeria