Production trends and yield predictive models for culture-based fisheries in irrigation reservoirs of Sri Lanka

Abstract

This study aims to develop empirical yield predictive models for CBF in perennial irrigation reservoirs of Sri Lanka, focusing on the GFP (M. rosenbergii), alongside carp and tilapia species. Conducted across 39 reservoirs, the research involved the collection of extensive data on species stocking densities, fish yields and various limnological parameters. Results indicate that stocking densities of carp and GFP significantly influenced yields, with optimal stocking densities identified as over 900 fingerlings ha-¹ yr-¹ for carp and approximately 1,000 post larvae ha-¹ yr-¹ for GFP in major reservoirs. Notably, the study found a significant relationship between fishing intensity and carp yield, although no such correlation was observed for GFP. Limnological assessments revealed that chlorophyll-a concentrations positively correlated with carp yields, while other parameters exhibited limited variability. TSI indicated that most reservoirs were classified as eutrophic. PCA highlighted key variables influencing productivity, with significant relationships established for carp yield. The study underscores the critical role of stocking strategies and limnological factors in optimising fish production, providing valuable insights for sustainable aquaculture development in Sri Lanka’s inland water bodies. The predictive models developed offer a framework for enhancing CBF, thereby contributing to improved livelihoods in rural communities reliant on freshwater fish as a vital protein source.