Freshwater Fish Migrations Are Disappearing Across the Planet, Finds U.N. Report
The assessment identified over 300 species of fish that urgently need international conservation effort
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Many people are familiar with the epic migrations of zebras and wildebeest across the Serengeti, but some of our planet’s most important migrations happen out of sight. The dorado catfish travels thousands of miles from the Andes to the Amazon. In the Mekong River, the 650-pound Mekong giant catfish once migrated hundreds of miles upstream. According to a new report, these major migrations are collapsing.
Dams, habitat loss and overfishing are causing freshwater fish around the world to disappear, reports the United Nations’ Convention on the Conservation of Migratory Species of Wild Animals (CMS) in a global assessment. The report found that migratory freshwater fish populations worldwide have declined by about 81 percent since the 1970s. It also identified 325 species as candidates for urgent international conservation actions.
“This is the first global assessment of migratory freshwater fish, and it shows just how much has gone unnoticed,” says Zeb Hogan, the report’s lead author and the CMS scientific councilor for freshwater fish, to Stefan Lovgren at Mongabay. “We’re only now beginning to understand the scale of these migrations, and how much they are at risk.”
The report highlights how vital migratory freshwater fish are to ecosystems around the world. They’re not only a source of food and income to millions of people—they also maintain the ecological balance of the rivers, lakes and wetlands they call home. Their decline, however, has received little attention. Only 24 of these fish are already listed by the CMS.
“This crisis has escaped global attention partly because it is taking place underwater,” says CMS Executive Secretary Amy Fraenkel in an email to Johnny Sturgeon at Inside Climate News.
The main culprits driving the decline of migratory freshwater fish are dams, habitat fragmentation, overfishing and climate-related flow changes. These threats are disrupting the connections between spawning and feeding grounds and floodplain nurseries.
When these connections are broken, fish populations can decline quickly. Since almost half of the world’s water basins are shared between more than one country, cooperation between countries is key to conserving migratory fish. “Rivers don’t recognize borders, and neither do the fish that depend on them,” says Michele Thieme, the deputy lead of freshwater for the World Wildlife Fund, to Mongabay.
For example, the Mekong Basin, which the report describes as a priority region, spans six countries, none of which are parties to CMS. “It highlights the need to bring more countries, especially in Southeast Asia, into CMS if species are going to be protected,” adds Zach Bess, a graduate student at the University of Nevada, Reno and co-author of the report, to Mongabay.
The decline of species in the basin is already impacting its fishery. The fishery—which produces 15 percent of the world’s inland catch—has seen its annual economic value drop from $11 billion to around $8 billion in recent years, says Hogan to Inside Climate News.
“It’s $3 billion, hundreds of thousands of tons of fish that would support millions of people. That’s the kind of loss we’re talking about,” he adds to the outlet, pointing to the critically endangered status of the Mekong giant catfish as evidence.
Other priority regions include the Amazon, Europe’s Danube, Africa’s Nile and South Asia’s Ganges-Brahmaputra.
“This new assessment offers a clearer picture of where international cooperation is most urgently needed,” Hogan writes in The Conversation. “It is up to humanity to protect these extraordinary aquatic animals, which support millions of people, enrich their lives, and make the world a more wondrous place.”/https://tf-cmsv2-smithsonianmag-media.s3.amazonaws.com/accounts/headshot/Sara_-_Headshot_thumbnail.png)