A stark warning has been issued regarding the alarming decline of migratory fish populations worldwide. Recent research indicates that these crucial aquatic species, which migrate vast distances for breeding, have seen their numbers plummet by an astonishing 81% over the past 50 years. The United Nations has now identified 30 flagship species, including the golden mahseer and goonch catfish, as top priorities for conservation efforts.
A Crisis of Migration
Fish species that traverse significant distances through rivers, lakes, and wetlands are grappling with an unprecedented array of threats. These include habitat destruction, pollution, and overfishing, which collectively hinder their ability to reach vital breeding grounds. The UN’s latest report examined over 15,000 freshwater migratory fish species, revealing a critical need for immediate protective measures.
Dr. Zeb Hogan, co-author of the report and a professor at the University of Nevada, Reno, stressed the importance of these fish, stating, “Freshwater fish support hundreds of millions of people globally, so for humans, they’re very important.” This diverse group not only provides sustenance for around 200 million individuals but also plays a pivotal role in the ecological balance of freshwater systems.
The Need for Urgent Action
The report highlights that the UN first evaluated the status of migratory fish in 2011, at which point only 3,000 species were assessed. The current analysis represents a significant expansion of knowledge, with 325 fish identified as needing inclusion in a global conservation treaty aimed at monitoring and supporting threatened migratory species. Among these are several species native to the UK, such as the Allis shad, River lamprey, Brook lamprey, and Atlantic salmon.
Michele Thieme, deputy lead for freshwater conservation at the World Wildlife Fund (WWF) US, elaborated on the cultural significance of certain species—such as the iconic golden mahseer, revered in the Himalayas for its spiritual importance. “It’s called the tiger of the river, and many of the people in that region value that fish for cultural and spiritual practices that go far beyond the economic values,” she explained.
Barriers to Survival
The challenges faced by migratory fish are particularly pronounced in Europe, where artificial barriers disrupt their natural routes nearly every kilometre. These obstructions, which often include outdated culverts and weirs, hinder fish from accessing spawning habitats, causing significant stress on their populations. Dr. Janina Gray, head of science at the environmental charity WildFish, noted, “The cumulative effect on migrating fish is enormous: it can have a massive impact in terms of the energy reserves fish are using to get over the barriers.”
As fish expend more energy to navigate these obstacles, they become more vulnerable to disease and predation, and their spawning success diminishes.
A Coordinated Global Effort
As many migratory fish traverse international borders during their life cycles, cohesive action between governments is imperative. The Convention on the Conservation of Migratory Species (CMS), a UN treaty established in 1979, calls upon nations to collaborate in safeguarding migrating species. The UN is advocating for the inclusion of the 30 identified fish species in the CMS at its upcoming meeting in three years.
The success of the CMS can be seen in the case of the saiga antelope, which experienced a dramatic recovery after being placed under its protection. Following a catastrophic die-off in 2015, an international anti-poaching initiative has helped the species rebound to over a million individuals. Amy Fraenkel, the UN Executive Secretary for CMS, acknowledged that while attention has often focused on more charismatic species, it is now time for migratory freshwater fish to receive similar support.
Why it Matters
The precipitous decline of migratory fish species signals a broader ecological crisis that threatens not just marine biodiversity, but also the livelihoods of millions who depend on these species for food and cultural practices. If immediate action is not taken to address the myriad threats they face, we risk losing these vital components of our ecosystems forever. This is a call to arms for governments, conservationists, and communities alike to unite in the preservation of our planet’s precious aquatic resources.