RETURNS TO SCALE AND PRODUCTION CONSTRAINTS IN CULTURED FISH FARMING IN OSUN STATE, NIGERIA
Publication Type: Journal Article.
Publication Year: 2026
Author(s): Olatunji, Rachel Femi, Baba, Kenneth C. and Olorunsanya, Eniola Oluwatoyin
Journal Name: (IJAEMD)
ABSTRACT
Cultured fish farming contributes significantly to food security, employment generation, and fish import substitution in Nigeria. However, variations in resource-use efficiency and production constraints continue to affect farmers’ productivity. This study examined the production elasticities, returns to scale, and production constraints of cultured fish farming in Osun State, Nigeria. A multistage sampling technique was used to select 120 cultured fish farmers from six Local Government Areas (LGAs) across the three Agricultural Development Programme (ADP) zones. Primary data were collected using structured questionnaires and analysed using the Cobb–Douglas production function and descriptive statistics. The results revealed that labour, feed quantity, fingerlings, and depreciation positively influenced fish output, although their elasticities varied across the LGAs. Feed elasticity ranged from 0.0190 to 0.0794, fingerlings from 0.0229 to 0.0576, and depreciation from 0.0179 to 0.6504. Farmers in Iwo, Ejigbo, and Obokun operated under decreasing returns to scale, whereas those in Ife Central, Olorunda, and Osogbo exhibited increasing returns to scale. Major production constraints included high feed costs, limited access to credit, inadequate extension services, disease outbreaks, poor access to quality fingerlings and unstable market prices. The study concludes that cultured fish farming in Osun State exhibits varying production efficiencies across the selected LGAs. Labour, feed quantity, fingerlings, and depreciation were the major determinants of fish output, while farmers in Ife Central, Olorunda, and Osogbo exhibited greater potential for output expansion under increasing returns to scale compared with those in Iwo, Ejigbo, and Obokun, who operated under decreasing returns to scale. This study recommends improving resource-use efficiency in areas with decreasing returns to scale while promoting investment, affordable credit, reduced feed costs, and strengthened extension services to enhance productivity and sustainable aquaculture development.
Keywords: Returns to scale; Elasticity of production; Total cost elasticity; Production constraints; Cultured fish farming