This report provides the most comprehensive global assessment to date of migratory freshwater fishes, documenting the scale, urgency, and opportunity for coordinated international action under the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It identifies hundreds of migratory, transboundary freshwater fish species in decline, explains why these species are ecologically, economically, and culturally vital, and highlights how river fragmentation, altered flows, overexploitation, pollution, and climate pressures are driving widespread losses. Drawing on global data and a focused Amazon Basin case study, the report pinpoints priority species and river basins where cooperation can deliver the greatest conservation gains, and outlines practical CMS pathways—such as species listings, action plans, concerted actions, and memoranda of understanding—to restore connectivity, align management across borders, and turn science into tangible recovery for some of the world’s most imperiled and important freshwater migrations.
