Recent research findings indicate that migratory freshwater fish populations have declined by over 80% since 1970.
According to the study, migratory freshwater fish populations are decreasing across all regions globally, with the most significant decline observed in South America and the Caribbean, where a staggering 91% reduction has been recorded over the past 50 years. This region hosts the largest migratory freshwater fish populations in the world; however, the construction of dams, mining activities, and water diversions are devastating river ecosystems. The Living Planet Index (LPI) reports that in Europe, migratory freshwater fish populations have decreased by 75%.
Migratory freshwater fish populations have declined by over 80% since 1970. (Image credit: nationalgeographic.com).
Meanwhile, the International Union for Conservation of Nature (IUCN) has released a report showing that 25% of freshwater fish species are at risk of extinction, with migratory species facing even greater threats. The data does not yet account for changes in Africa, but researchers believe that many species in this region are also facing stress factors.
Migratory freshwater fish are partially or entirely dependent on freshwater systems, with some being born in the sea and migrating back to freshwater or vice versa. They form a crucial part of the daily diet and livelihoods of millions of people worldwide. However, many rivers no longer have their natural flow due to the construction of dams and other barriers that hinder fish migration. Additionally, other factors such as pollution from urban wastewater, industrial effluents, surface runoff from roads, and agricultural activities are also contributing to the decline. Climate change is further altering habitats and impacting freshwater systems. Unsustainable fishing practices pose another significant threat.
The founder of the World Fish Migration Foundation (WFMF), expert Herman Wanningen, asserts that the catastrophic decline of migratory fish populations serves as a wake-up call for the world, urging global action to save these species and the rivers they inhabit. The authors of the study also advocate for the restoration and protection of rivers, as well as the removal of barriers to the migratory habits of fish. Researchers are also promoting the search for renewable energy solutions as alternatives to the thousands of new hydropower projects planned worldwide. Last year, a record 487 barriers were removed in 15 European countries.
Dr. Anthony Acou from the French National Research Institute for Agriculture, Food, and Environment (INRAE) emphasizes that because many migratory fish spend most of their lives at sea, it is crucial to gain a better understanding of the impacts on both marine and freshwater habitats to implement effective management measures.
