This alarming decline affects hundreds of species that depend on connected waterways to reach feeding grounds, breeding areas, and nursery habitats across continents.
Scientists say this collapse of freshwater migrations is one of the most severe biodiversity losses on Earth and highlights the urgent need for coordinated conservation efforts.
According to the Convention on the Conservation of Migratory Species of Wild Animals (CMS), migratory freshwater fish once moved freely along long river systems such as the Amazon, Nile, Mekong, Danube, and La Plata‑Paraná.
But today, dams, habitat fragmentation, pollution, overfishing, and changes in water flows have cut off these pathways. As a result, many species can no longer complete their life cycles, which has led to dramatic population declines.
The report found that 325 migratory freshwater fish species now require international protection, though only a few are currently listed under global conservation agreements.
Of those already evaluated, 97% are threatened with extinction, underscoring how quickly the crisis is unfolding. Experts stress that managing rivers as connected ecosystems rather than treating them as separate national waterways is crucial to slowing or reversing declines.
Lead author Dr. Zeb Hogan highlighted that “many of the world’s great wildlife migrations take place underwater,” and their loss is “a sign of rapidly deteriorating freshwater environments.”
The CMS and conservation partners are calling for transboundary cooperation to restore river connectivity, protect migration corridors, and implement basin‑wide strategies to support both aquatic life and human communities that depend on these fish for food and livelihoods.
Leave a Reply