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Global conservation push targets declining migratory fish
Freshwater migratory fish, critical to ecosystems and human livelihoods, have seen their populations plummet by 81% over the past 50 years, a new UN report reveals. The study highlights 30 priority species-including the golden mahseer and goonch catfish-for urgent protection under a global treaty.
Scale of the crisis
An international team of scientists assessed 15,000 migratory freshwater fish species, which account for half of all fish globally. The findings underscore a sharp decline driven by dams, pollution, and overfishing, disrupting breeding cycles and threatening food security for millions.
Dr. Zeb Hogan, a biology professor at the University of Nevada, Reno and co-author of the report, emphasised the group's ecological and economic importance. "These fish support hundreds of millions of people worldwide, providing food for 200 million," he said. "Their diversity is staggering-from 650-pound giants migrating 7,000 miles to tropical eels traversing Oceania."
Priority species and cultural significance
The UN identified 325 fish requiring monitoring, narrowing the focus to 30 flagship species, including the UK's Allis shad, river lamprey, brook lamprey, and Atlantic salmon. These species were selected for their ecological vulnerability and cultural value.
"The golden mahseer, known as the 'tiger of the river,' holds spiritual and cultural significance in the Himalayas, far beyond its economic worth,"
Michele Thieme, Deputy Lead for Freshwater, World Wildlife Fund US
Thieme noted that habitat loss-particularly from dams-and overfishing are the primary threats. "Dams fragment rivers and alter natural flows, preventing fish from reaching spawning grounds," she said.
Barriers to migration
In Europe, migratory fish face obstacles every kilometre on average, often from small, redundant structures like weirs. Dr. Janina Gray, head of science at WildFish, warned that these barriers drain fish energy reserves, increasing vulnerability to disease and predation. "They may spawn in suboptimal locations, further jeopardising populations," she said.
Call for international cooperation
Most migratory fish cross national borders, requiring coordinated action between governments. The UN's Convention on the Conservation of Migratory Species (CMS), established in 1979, aims to protect such species through global collaboration. The report proposes adding the 30 priority fish to the CMS list at its next meeting in 2029.
Amy Fraenkel, the CMS Executive Secretary, pointed to the Saiga antelope as a success story. After a 2015 mass die-off, international anti-poaching efforts helped its population rebound to over a million. "The focus has long been on charismatic species like big cats and whales," she said. "Now, it's time for migratory fish to receive the same attention."
Next steps
The UN's proposal will be reviewed at the CMS conference, where member states will decide on listing the 30 species. If approved, it would mandate cross-border conservation efforts to restore declining populations.
