Freshwater migratory fish are facing a significant crisis, with a staggering 81% decline in their populations over the past 50 years. A new report from the United Nations highlights the urgent need for conservation efforts, identifying 30 key species—including the golden mahseer and goonch catfish—that require immediate protection. This alarming trend, driven by habitat destruction, pollution, and overfishing, threatens not only the fish themselves but also the livelihoods of millions who depend on them.
A Crisis Unfolding in Freshwater Ecosystems
Fish species that undertake extensive migrations through rivers, lakes, and wetlands are now at a critical juncture. These creatures, which play vital roles in their ecosystems, are increasingly hindered by anthropogenic factors. Dams obstruct their migratory routes, while pollution compromises their habitats, and overfishing depletes their numbers.
Dr. Zeb Hogan, a biology professor at the University of Nevada, Reno and co-author of the report, emphasised the importance of these fish. “Freshwater fish support hundreds of millions of people globally,” he stated, adding that they provide sustenance to about 200 million individuals. The diversity of migratory fish varies widely, with species capable of travelling vast distances, such as the golden dorado in South America and tropical eels in Oceania.
The UN’s Comprehensive Assessment
For the first time since 2011, the UN has expanded its evaluation to include over 15,000 species of freshwater migratory fish, a significant increase from the previous assessment of just 3,000. The findings reveal a dire situation, prompting the identification of 325 fish species that need to be added to a global conservation agreement aimed at protecting threatened migratory wildlife. Among these, 30 species have been prioritised for urgent conservation measures, including several found in the UK, such as the Allis shad and Atlantic salmon.
Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, highlighted the cultural significance of some of these species. The golden mahseer, revered in the Himalayas, faces threats from habitat loss and overfishing, which undermine both its ecological role and its cultural importance.
The Need for Collaborative Action
The obstacles to migration are especially pronounced in Europe, where fish encounter barriers every kilometre on average. These barriers range from small culverts to redundant weirs, which can drastically affect fish migration. Dr. Janina Gray, head of science at WildFish, noted the cumulative impact of these barriers: “They can significantly affect the energy reserves fish use to overcome obstacles, making them vulnerable to disease and predation.”
To combat these challenges, international cooperation is essential. Many migratory species cross national borders, necessitating concerted efforts among governments to address the threats they face. The UN’s Convention on the Conservation of Migratory Species, established in 1979, serves as a framework for this collaboration. The UN is now advocating for the inclusion of the 30 priority fish species in the treaty during its upcoming annual meeting in three years.
Learning from Successful Conservation Efforts
Conservation successes in other species offer hope for migratory fish. The saiga antelope, for instance, has seen a population rebound from the brink of extinction following international conservation initiatives. Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species, acknowledged the disproportionate focus on more visible species like big cats and whales, stating that it is time for migratory freshwater fish to receive similar attention and coordinated action.
Why it Matters
The decline of migratory fish has far-reaching implications, not only for biodiversity but also for human communities that rely on these species for food and cultural identity. As ecosystems become increasingly fragmented, the need for urgent action becomes clear. Protecting these fish is essential not only for their survival but also for the health of the rivers, lakes, and wetlands they inhabit, ultimately safeguarding the livelihoods and cultures of countless communities around the world.
