The Growing Industry of Cage Fish Farming in Sub-Saharan Africa

Allan Ochieng vividly recalls the devastation that struck the fish farmers of Lake Victoria late last year. Thousands of fish met their demise due to a natural phenomenon called upwelling, where deep waters mix with surface water, depleting dissolved oxygen and leading to fish fatalities. Some speculate that increased algae levels or pollution may have contributed to the disaster. Mr. Ochieng himself lost 120,000 tilapia, with nearly half of them ready for harvest. His story echoes that of many other fish farmers who suffered similar losses.

Mr. Ochieng, however, remains committed to his venture, owning 24 cages along the Kenyan shoreline, an investment totaling $100,000. In addition, they spent $185,000 on baby tilapia, feed, and labor. Despite the substantial risks involved, cage fish farming has gained prominence in sub-Saharan Africa due to the decline in wild fish stocks and the rising demand for fish. The number of cages increased from just nine in 2006 to over 20,000 in 2019, according to a study published in Nature Food. In East Africa, the industry tripled in size between 2017 and 2021, according to a report by Gatsby Africa.

Cage aquaculture is not a simple endeavor. It involves raising fish in net cages submerged in water. As the industry has grown, it has become increasingly high-tech, reliant on data and technology to ensure fish health and prevent disasters like upwelling. For instance, companies like Yalelo Zambia, one of Sub-Saharan Africa’s largest tilapia producers, collect extensive data. This data includes measurements of dissolved oxygen, pH values, and ammonia content in the water. Monitoring these parameters enables them to anticipate upwelling and reduce the number of fish in cages to prevent fish mortality.

Victory Farms, Kenya’s largest caged fish producer, has similarly embraced data collection to minimize risks. They measure various aspects of underwater activity and biology, including algae levels in the lake as an indicator for upwelling. With years of data, they can predict the risk level and adjust stocking densities and feeding accordingly.

Innovations are continuously emerging in this sector. For instance, Victory Farms has developed a mobile incubation system to transport fish eggs more safely. Such advancements aim to professionalize the sector and enhance its productivity.

However, many small-scale fish farmers face challenges in adopting these high-tech solutions. The cost of necessary equipment for measuring oxygen levels can be prohibitive, often exceeding $1,000. Additionally, some farmers lack the knowledge required for successful cage placement, risking water pollution in shallow waters.

Efforts are underway to simplify the adoption of technology in this sector. AquaRech, for example, is working on a system to monitor water temperature in cages, enabling precise feeding recommendations. Such innovations can lead to healthier fish and cost savings.

While the cage fish farming industry is growing rapidly, concerns are also being raised. The accumulation of uneaten feed and fish waste beneath the cages may impact water quality. Responsible cage placement and regular water testing are essential to mitigate these environmental concerns.

The industry’s growth is not without its critics, but for now, it appears to be addressing the demand for fish in a region where wild fish stocks have declined due to overfishing. With technology and responsible practices, cage fish farming holds promise as a significant contributor to the food supply and local economies in sub-Saharan Africa.