Science to practice in culture-based fisheries in Sri Lankan reservoirs: synthesis and lessons learned

Abstract

Culture-based fisheries (CBF) in Sri Lankan reservoirs play a pivotal role in enhancing rural livelihoods, yet their long-term sustainability is constrained by inefficiencies in reservoir selection, stocking strategies and fisheries management. This study introduces a performance-based reservoir classification system, moving beyond conventional hydrological classifications to incorporate ecological and bathymetric parameters for optimised stocking decisions. Findings indicate that bathymetry, often overlooked in stocking models, is a key determinant of giant freshwater prawn (GFP) productivity. Results indicate that optimal stocking densities should be adjusted based on reservoir type, with a maximum of 1,000, 1,500 and 2,000 post larvae (PL) per hectare for major, medium and minor reservoirs, respectively. Genetic integrity of broodstock emerged as a significant concern, with potential risks associated with the repeated use of reservoir-derived stocks. The study underscores the need for a national broodstock management program integrating genetic monitoring, screening and controlled breeding protocols. Additionally, findings highlight inefficiencies in fishery extension services, including suboptimal resource allocation and inadequate monitoring frameworks, necessitating a data-driven decision support system for more effective management. The introduction of trap-based fishing methods was explored as an alternative to conventional gillnets, with potential benefits for selectivity and product quality. However, policy considerations are essential to prevent conflicts in common-property reservoirs. Public–private interventions (PPI) were identified as a key driver for CBF expansion but concerns over regulatory oversight and equitable access must be addressed. The study also highlights the vulnerabilities of CBF to climate change, advocating for climate-smart stocking protocols and hydrological modelling to enhance resilience. By aligning Sri Lanka’s CBF strategies with international best practices, these findings provide a robust framework for enhancing productivity, ecological sustainability and socioeconomic resilience in inland fisheries. Future research should focus on digital bathymetric mapping, genetic conservation efforts and adaptive management models to further refine CBF sustainability.