I was born by the Magdalena River in Colombia, where I learned to swim as a child – back when I was still smaller than the bagre, the great catfish my family pulled from the water. Each year came la subienda, the great seasonal migration, when millions of bocachico surged upstream together, traveling hundreds of kilometers toward the cool Andean headwaters to spawn, and the river churned and flashed silver, so thick with life it felt as though you could almost walk across their backs. Their return was an event. A kind abundance that set the rhythm of life itself, the kitchen, and the mood of whole communities.
The bagre is a migrant too, but a different kind. Where the bocachico travels in vast, shimmering crowds toward the Andean headwaters to spawn, the catfish moves alone and unwitnessed – navigating by current and instinct through the dark depths of the Magdalena, following the pulse of the river’s rising and falling waters into the flooded lowlands where it was born.
It is with that history that I follow this week’s Convention on Migratory Species (CMS) COP15, the global conference on the conservation of migratory species, gathering in Campo Grande, Brazil, at the edge of the Pantanal, one of the most biodiverse places on Earth. For those of us who grew up beside rivers, this moment is not abstract. It is personal.
A Crisis Unfolding Beneath the Surface
Migratory freshwater fish are among the planet’s most remarkable travelers. What I didn’t know as a child, what most people never know, is that the bagre we ate on the beach had already traveled hundreds of kilometers before it was pulled from the water. Species like the golden dorado and the goliath catfish navigate thousands of kilometers across river systems, crossing political borders, connecting Andean headwaters to distant coastal nurseries. The dorado catfish alone undertakes a journey of more than 10,000 kilometers, one of the longest freshwater migrations ever recorded. These are not small wonders. They are among the greatest wildlife migrations on Earth. And most people have never heard of them.
That invisibility is part of the problem. While the world has focused on collapsing populations of terrestrial and marine animals, a largely hidden crisis has been unfolding beneath the waterlines of the world’s great rivers. A new report Global Assessment of Freshwater Fishes launched at CMS COP15 this week lays out the scale of what we are losing: migratory freshwater fish populations worldwide have declined by roughly 81% since 1970, one of the steepest drops ever recorded for any major vertebrate group. Nearly all(97%) of the migratory fish species already listed under the Convention are threatened with extinction.
And that is only the species being tracked. The same report, drawing on IUCN evaluations of nearly 15,000 species identifies 325 additional migratory freshwater fish that meet the criteria for international protection but remain unlisted, falling through the cracks of the very agreements designed to protect them. In South America alone, 55 species are candidates. The crisis spans the world’s great river systems: the Amazon and La Plata–Paraná, Europe’s Danube, Asia’s Mekong, Africa’s Nile, the Ganges–Brahmaputra. Across shared river basins that cover 47% of Earth’s land surface, conservation cannot succeed without countries working together.
The causes are well understood: dams that block ancient migration corridors, altered river flows, habitat fragmentation, pollution, overfishing, and the accelerating disruption of climate change. When rivers are severed, when a fish that needs 10,000 kilometers of connected waterway finds a dam instead, populations can collapse with devastating speed.
The numbers matter. But so does what lies behind them.
From the Magdalena in Colombia to the Marañón in Peru, migratory fish are the living foundation of cultures, economies, and food systems that have sustained communities for generations. In the Amazon alone, migratory species account for roughly 93% of all fisheries landings, underpinning regional fisheries valued at an estimated US$436 million annually. When these fish disappear, entire ways of life go with them, according to the Global Assessment of Migratory Freshwater Fishes, CMS 2026)
I know this not only as a river defender, but as someone who grew up in relation to a river, who learned the world through its currents, its seasons, its gifts. That is why the words of Rodrigo Antonio Morales, President of the Colombian Federation of Fishingfolks and Environmentalists (FECOLPAA), land so close to home:
Migratory fish represent culture and tradition, food sovereignty, gastronomy, employment, economy, and tourism. Yet dams have disrupted the reproductive cycles of native species and altered the river’s ecosystems, affecting not only fisheries but also agricultural systems that depend on the natural flow of the Magdalena. Protecting these species and conserving the Magdalena River basin means safeguarding life and livelihoods across the entire territory sustaining more than 350,000 families, along with another 270,000 people who depend on seasonal fishing.
Further south, in the Peruvian Amazon, Mari Luz Canaquiri, a Kukama leader and 2025 Goldman Environmental Prize recipient, describes how deeply these losses are being felt:
When my grandparents lived along the Marañón River, there were abundant migratory fish like the dorado. They fished with spears and harpoons, and nothing was wasted. Our grandmothers preserved and prepared it to feed the children, strengthening them and sustaining future generations. Today, many of these species have disappeared. Pollution, oil spills, and extractive activities are forcing fish to migrate or die. What remains is not enough to feed our communities. This is not only a loss of food, it is a growing crisis of health, nutrition, and dignity for our people.
Because migratory fish cross borders, their protection cannot rest on national policies alone. As the lead author of the new global assessment, Dr. Zeb Hogan, puts it: protecting migratory freshwater fish “will require countries to work together to keep rivers connected, productive, and full of life.”
This is precisely what CMS was built to do. The Convention is the only global, UN-based framework designed specifically for migratory species. Ecological connectivity, defined by CMS as “the unimpeded movement of species and the flow of natural processes that sustain life on Earth” is its central purpose. When dams, diversions, and degraded habitats sever that connectivity, the consequences cascade across entire river basins and across generations.
CMS COP15 presents a pivotal moment. Governments meeting in Brazil this week have the power to formally list additional threatened migratory fish species, triggering cross-border protections for the first time. A Multi-Species Action Plan for Amazonian Migratory Catfish developed in cooperation with Brazil, Bolivia, Colombia, Ecuador, Peru and Venezuela, is on the table for adoption this week. It calls for coordinated monitoring, the mapping of migration corridors, and concrete measures to remove barriers to fish passage. These are achievable steps, grounded in science and regional cooperation.
And they must be taken in a way that centers the rights and knowledge of Indigenous Peoples and local communities, who have stewarded these rivers for generations, and whose voices must shape the decisions made in their name.
At International Rivers, Executive Director Josh Klemm sees COP15 as the moment to turn that principle into action:
You cannot protect migratory fish without protecting the rivers they depend on, and you cannot protect rivers without protecting the rights of the communities who know them best. CMS COP15 is a once-in-a-generation opportunity to get this right. The science is clear, the communities most affected are speaking. Now governments must act.
As Mari Luz puts it, the stakes reach far beyond any single river:
“I call on people around the world: women, men, and young people to take responsibility for protecting our rivers. Rivers are sacred. They are the source of life. We must care for them so that we can continue to have clean water, healthy ecosystems, and fish to feed our communities. Only then can we truly live well.”
The decisions made this week in Campo Grande will not stay in Campo Grande. Listings under CMS Appendix II create binding obligations to coordinate across borders, map migration corridors, and align fisheries management with ecological reality. The Multi-Species Action Plan for Amazonian Migratory Catfish, if adopted, would be the most ambitious transboundary freshwater fish conservation effort ever undertaken in South America. But agreements on paper mean nothing without rivers that still flow, and protecting migratory fish requires more than listing species. It requires confronting the dams that sever their routes and the pollution that poisons their waters, while also investing in the alternatives that make those changes possible: renewable energy that doesn’t block rivers, irrigation systems that don’t depend on destroying them. And it requires centering the communities who have stewarded these rivers for generations, not as stakeholders to be consulted at the end of the process, but as the knowledge holders on whom any lasting solution depends.
I think of the bagre navigating the dark depths of the Magdalena – alone, unwitnessed, following currents that have guided its kind for millions of years. It knows only whether the river is open or closed, clean or poisoned, alive or dying. Right now, across the world’s great river systems, the river is more often closed, poisoned, dying. We still have time to change it, but not without courage from the governments gathered in Brazil this week, and from all of us who refuse to let a living river become only a memory.
Photos: Courtesy of Zeb Hogan
