Freshwater fish that undertake extensive migrations are facing a crisis, with populations declining by an alarming 81% over the past fifty years. This sharp decrease, driven by factors such as habitat destruction, pollution, and overfishing, has prompted global conservation efforts spearheaded by the United Nations. In a recent report, researchers have identified 30 key species, including the golden mahseer and goonch catfish, that urgently require protection to ensure their survival and the health of aquatic ecosystems.
A Crisis Ignored for Too Long
For decades, migratory fish species have been overlooked in conservation discussions, despite their critical role in supporting the livelihoods of millions. Dr. Zeb Hogan, a biologist at the University of Nevada, Reno and co-author of the UN report, emphasises their importance: “Freshwater fish support hundreds of millions of people around the world. They provide food for 200 million people globally and boast immense diversity that urgently needs safeguarding.”
The report marks a significant step forward in understanding the plight of these fish, as it expands the assessment from 3,000 species in 2011 to over 15,000 today. Among the identified species needing immediate attention, 325 are highlighted for inclusion in a global agreement aimed at monitoring and bolstering threatened migratory populations. Notably, four of these priority species—Allis shad, river lamprey, brook lamprey, and Atlantic salmon—are native to the UK.
The Dual Threat of Overfishing and Habitat Loss
The golden mahseer, revered in the Himalayas as the “tiger of the river,” faces severe threats from both overfishing and the destruction of its habitat. Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, notes the cultural and spiritual significance of this fish to local communities, stating, “Many people in that region value that fish for cultural and spiritual practices that go far beyond economic values.”
Similarly, the goonch catfish, known for its impressive size, is struggling to migrate as rivers like the Indravati are increasingly developed. Dams disrupt natural river systems, obstructing access to vital spawning grounds. Thieme explains that such habitat loss is a pressing issue, stating, “Dams fragment river systems and alter natural flow regimes, preventing fish from reaching their spawning habitats.”
Barriers to Migration in Europe
European migratory fish are particularly affected by barriers that impede their journeys. On average, fish encounter an obstruction every kilometre, whether it’s a small culvert or a redundant weir. Dr. Janina Gray, head of science at the environment charity WildFish, highlights the cumulative impact of these barriers, explaining: “The energy reserves fish expend overcoming these obstacles can make them more susceptible to disease, predation, and spawning in suboptimal locations.”
To address this issue, international collaboration is essential. Many migratory species traverse borders, necessitating coordinated conservation efforts across nations. The Convention on the Conservation of Migratory Species—a UN treaty established in 1979—encourages countries to work collectively towards the protection of migratory species.
The Path Forward: A Call to Action
The UN is now advocating for the inclusion of 30 endangered migratory fish species in the treaty during its next annual meeting in three years. This move aims to foster greater international cooperation in their conservation. Historical precedents, such as the recovery of the saiga antelope through concerted international efforts, serve as a beacon of hope for fish species facing similar threats.
Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species, acknowledges the past focus on more prominent species, stating, “The time has come for migratory freshwater fish to benefit from coordinated action.” This shift in attention could be pivotal for the survival of these vital species.
Why it Matters
The decline of migratory fish populations is not just an environmental concern; it poses a direct threat to global food security and the livelihoods of countless communities dependent on these fish. Protecting these species is essential for maintaining biodiversity and the health of freshwater ecosystems. As the UN ramps up its efforts, the call for urgent action resonates louder than ever—our planet’s aquatic future hangs in the balance.
