Conservationists have stressed the urgent need to protect migratory fish species from extinction amid growing environmental threats.

Several species that migrate through rivers, lakes and ponds are facing combined pressures from dams, pollution and overfishing, which hinder their ability to reach breeding grounds and sustain their populations.

According to a new assessment by the Convention on the Conservation of Migratory Species of Wild Animals (CMS), a United Nations environmental treaty, some of the most significant animal migrations on Earth occur beneath the surface of rivers, many of which are now rapidly collapsing. Iconic species such as the Golden Mahseer and Goonch catfish are among 30 flagship freshwater fish prioritised for global conservation in the report.

The study assessed more than 15,000 species of freshwater migratory fish, representing about half of all fish species globally and found that their populations have declined by an estimated 81 per cent over the past 50 years.

Co-author of the report and Professor of Biology at the University of Nevada, Zeb Hogan, emphasised the critical role freshwater fish play in sustaining livelihoods. “Freshwater fish support hundreds of millions of people around the world. They provide food for about 200 million people globally and represent immense biological diversity that must be protected,” he said.

Hogan noted the extraordinary range of migratory fish species, from those weighing over 295 kilogrammes to species capable of travelling more than 7,000 miles. “You have fish of every shape and size imaginable—from large species to beautiful golden dorado that undertake long-distance migrations in South America, to tropical eels that travel thousands of miles in Oceania,” he added.

The report also identified 325 additional species that should be included in a global agreement aimed at monitoring and protecting threatened migratory animals. Some of these species are found in the United Kingdom, including Allis shad, river lamprey, brook lamprey and Atlantic salmon. Many of the listed species are not only threatened but also hold cultural and economic significance for communities worldwide.

A regional breakdown shows that Asia accounts for the largest number of threatened species (205), followed by South America (55), Europe (50), Africa (42) and North America (32). Priority river basins highlighted in the report include South America’s Amazon and La Plata–Paraná systems, Europe’s Danube, Asia’s Mekong, Africa’s Nile, and the Ganges–Brahmaputra basin in the Indian subcontinent.

The report, prepared by CMS scientific experts using global datasets and IUCN assessments, provides one of the most comprehensive overviews to date of migratory freshwater fish conservation needs.
It outlines practical measures governments can implement immediately, including protecting migration corridors and environmental flows, adopting basin-wide management plans, strengthening transboundary monitoring, and coordinating seasonal fishing practices.

Deputy Lead for Freshwater at World Wildlife Fund (WWF) US, Michele Thieme, highlighted the ecological and cultural importance of these species. “The Golden Mahseer is an iconic fish of the Himalayas, often called the ‘tiger of the river’. It holds deep cultural and spiritual value for many communities, beyond its economic importance,” she said.

She warned that the crisis affecting migratory fish is more severe than widely recognised. “Rivers do not recognise borders, and neither do the fish that depend on them. The crisis unfolding beneath our waterways is far more severe than most people realise, and we are running out of time. Rivers must be managed as connected systems, with coordination across borders and investments in basin-wide solutions before these migrations are lost forever,” she added.