East Africa’s Vanishing Migratory Fish Threaten Food Security
Rufiji, Tanzania – A growing crisis is unfolding along the Rufiji River in Tanzania, and across East Africa, as populations of migratory freshwater fish plummet, threatening the livelihoods and food security of millions. At the Nangurukuru fish market in Tanzania’s Lindi region, the once-abundant catches are dwindling, leaving traders and fishermen facing an uncertain future.
“The big Kambale are hard to find these days,” laments 68-year-old fisherman Hamisi Juma, reflecting a sentiment echoed throughout river communities. For generations, seasonal floods have sustained fish stocks by allowing species like catfish to breed and replenish their numbers. But that natural cycle is now broken.
The decline in the Rufiji is not an isolated incident. A new global assessment, backed by the United Nations’ Convention on Migratory Species, reveals that migratory freshwater fish populations have declined by a staggering 81 percent since 1970 – one of the most dramatic drops recorded for any group of vertebrates. The report identifies 42 species in Africa as being in urgent need of conservation action.
Scientists attribute the collapse to a complex interplay of factors: river fragmentation caused by dams, pollution, overfishing, and the escalating impacts of climate change. These fish depend on free-flowing rivers to complete their life cycles, yet waterways across Africa are increasingly being dammed, diverted, and degraded.
“Fish is our main source of protein,” explains Asha Mrope, a trader at the Nangurukuru market. “When they disappear, everybody at home is affected.”
Dr. Zeb Hogan, lead author of the UN assessment, emphasizes the direct link between dwindling fish populations and food security. “Freshwater fisheries provide food and livelihoods for hundreds of millions of people around the world, especially in rural and low-income countries,” he said. “These fisheries are worth billions of dollars and provide the majority of protein to people living along rivers with major fisheries.”
The problem extends beyond Tanzania, impacting vital fisheries in Lake Victoria – shared by Tanzania, Uganda, and Kenya – and major river systems like the Nile, Congo, and Niger.
The construction of infrastructure projects, like the Julius Nyerere Hydropower Dam on the Rufiji River, exemplifies the difficult trade-offs facing policymakers. While offering the promise of increased electricity and economic growth, such projects can have devastating ecological consequences.
“Keeping rivers healthy and free-flowing keeps aquatic ecosystems full of fish for the benefit of people and the environment,” Hogan argues.
Climate change is exacerbating the situation, with shifting rainfall patterns disrupting flood cycles and increasing pollution. As fish become scarcer, some fishermen resort to destructive practices, like using smaller-mesh nets that capture juvenile fish before they can reproduce.
Addressing this crisis requires a multi-faceted approach, experts say. Protecting migration corridors, restoring environmental flows, improving fish passage around dams, and strengthening fishing regulations are all crucial steps. Greater international cooperation is also essential, as many of these rivers cross national borders.
“Fish do not recognise borders,” notes Hilda Mpangala, a scientist at the University of Dar es Salaam. “But too often our policies do.”
The decline of migratory fish is a quiet warning, signaling a growing threat to food security and the livelihoods of communities across Africa. Finding a balance between development and ecological preservation is no longer a choice, but a necessity.