Descriptive Characterization of Cage Aquaculture Production Practices in Lake Victoria, Kenya to Improve Fish Health Management

Abstract

Within the past 10 years, cage culture of Nile tilapia in Lake Victoria has transformed from a nascent, small-scale enterprise into an immense, commercial industry. Today, several thousand cages with widely varying production scales supply nutrient-dense fish to communities highly dependent on aquatic foods. Despite the fundamental contributions of fish health management practices to the resiliency and environmental sustainability of aquaculture in Lake Victoria, adequate information on production practices in this industry is significantly lacking. To identify existing management practices, production constraints, and gaps in knowledge, we conducted a cross-sectional survey of 172 cage farm operations across all riparian counties in Lake Victoria, Kenya. Descriptive analysis was implemented to characterize the cage aquaculture industry. Cage farmers utilize a range of successful practices to maintain efficient production, fish health, and water quality; yet, significant management gaps remain. Survey data indicate that biosecurity practices are strikingly absent in the Kenyan cage aquaculture industry: many farmers report inadequate disposal of diseased fish, common incidence of large-scale fish kills, limited disease reporting, infrequent disinfection of tools, and poor access to antimicrobial therapeutics. Algal blooms were identified as a major production constraint and were reported to reduce fish growth/survival, decrease feed consumption, clog cage nets, and trigger fish kills. Large-scale fish kills, particularly in the absence of biosecurity and fish health management, threaten the food security and livelihoods of Lake Victoria communities. To our knowledge, our study is the first to systematically document the location and impacts of large-scale fish kills in Lake Victoria cage aquaculture systems. Cage farmers are rapidly adopting the use of commercial feeds, yet feed prices and availability remain volatile. The vast majority of farmers do not produce their own fingerlings, underscoring a critical dependency on private and government-run hatcheries that have not been well-characterized. In identifying gaps in management practices and production constraints, this study provides more specific targets for subsequent farmer training and education. Adoption of biosecurity practices can reduce the risk and magnitude of major fish kill events, thereby improving both economic and fish health outcomes. Concurrently, uptake of improved production practices can dramatically increase the efficiency of cage production systems and drive higher farmer incomes and reduced environmental impacts of aquaculture.

Keywords: biosecurity, tilapia, small-scale aquaculture, fish farming, fish kills