Optimizing stocking density for enhanced fish yield in lacustrine cage aquaculture
Christopher Mulanda Aura, Hezron Awandu, Venny Mziri, Fonda Jane Awuor, Chrispine S. Nyamweya, Safina Musa
Abstract
• The stocking density and fish yield in cage aquaculture operations explored for optimal utilization and management. • Field surveys across landing sites collected data on cage dimensions, stocking density, and fish yield. • Densities beyond the optimal range negatively affected fish health and water quality. • Adhering to recommended stocking density guidelines supports better fish growth and promotes sustainable aquaculture and environmental practices. Fish provides an essential source of high-quality protein and micronutrients, supporting food security worldwide. However, with declining wild fish stocks, cage aquaculture has emerged as a critical method for boosting fish production, particularly in Lake Victoria, Kenya. Stocking density is a crucial factor influencing fish growth, survival, and environmental sustainability, yet optimal practices remain poorly defined under natural lake conditions. This study assessed the relationship between stocking density and fish yield across cage farms in five riparian counties of Lake Victoria, linking management practices to fish health outcomes. Field surveys were conducted in 2023 across 42 landing sites, collecting data on cage sizes, stocking densities, anticipated harvest weights, and incidences of fish kills. Statistical analyses revealed a weak positive correlation ( r = 0.229) between mean stocking density and anticipated harvest weight. Cages stocked within the recommended range (70–150 fish m⁻³) achieved better growth and fish health outcomes, while sub-optimal densities were associated with reduced yields and higher fish mortality, especially in gulf regions vulnerable to poor water quality. This study provides crucial insights by linking real-world stocking density practices to fish mortality under open-water cage culture conditions. Findings emphasize the need for site-specific management, adherence to stocking guidelines, and targeted farmer training to optimize production while preserving ecosystem health. The outcomes are directly relevant for policy makers, extension officers, and researchers aiming to promote sustainable cage aquaculture in African freshwater systems.