Understanding Underwater Migrations
“It’s difficult to grasp the underwater activity when observing a river, yet billions of fish undertake remarkable migrations, some of the largest animal migrations on our planet,” stated Dr. Zeb Hogan from the University of Nevada.
The Dorado Catfish’s Remarkable Journey
The dorado catfish holds the record for the longest migration among freshwater fish, covering 7,000 miles (11,000 km) from the Andes foothills to the Amazon estuary and back. Hogan noted the impressive size of these fish, which can grow up to 2 meters in length.
Decline of Fish Populations
Fish migrations are prevalent in rivers globally, with salmon and eels being more commonly recognized examples. However, many of these migrations are declining rapidly. A recent assessment by the UN Convention on the Conservation of Migratory Species (CMS), spearheaded by Hogan, revealed that freshwater fish populations have fallen by approximately 81% since 1970.
Vulnerabilities to Human Impact
Freshwater species are particularly susceptible to human-induced threats, such as pollution seeping into rivers and lakes, dams obstructing critical waterways, and overfishing leading to significant population declines. The escalating climate crisis further exacerbates these issues by increasing water temperatures.
The Need for International Collaboration
“Animal migration is one of nature’s wonders,” remarked Amy Fraenkel, the executive secretary of CMS. “These journeys, which cross numerous international borders, are extraordinary feats of endurance. However, these species face increasing pressures at various stages of their life cycles. International collaboration is crucial for their survival and prosperity.”
Importance of Migratory Freshwater Fish
Migratory freshwater fish are vital for significant inland fisheries that support hundreds of millions of people, yet they rank among the most endangered species globally. The Tonlé Sap lake in Cambodia, part of the Mekong river system, is home to over 100 migratory species; Hogan highlighted, “They can catch several tons of fish in an hour.”
Global Action for Protection
The 132 countries participating in the CMS convened in Brazil, recognizing the Amazon as a crucial refuge for migratory freshwater fish. Enhancing international cooperation to protect these fish is a primary focus, with actions including removing barriers in rivers, ensuring adequate water flow, addressing pollution, and coordinating fishing efforts.
