In a sobering revelation, a new UN report has highlighted the drastic decline in migratory fish populations worldwide, with startling figures showing an estimated 81% drop over the past fifty years. This alarming trend is attributed to a combination of habitat destruction, pollution, and overfishing, threatening not only the fish species themselves but also the livelihoods of millions who rely on them.
The Plight of Migratory Fish
Migratory fish, which traverse vast distances in search of breeding grounds, are facing unprecedented challenges. Species such as the golden mahseer and the goonch catfish are now among thirty key species that the UN has prioritised for conservation efforts. A team of international scientists evaluated over 15,000 species of freshwater migratory fish—representing half of all fish species—and found that these vital ecosystems are in dire need of protection.
Dr. Zeb Hogan, a biology professor at the University of Nevada, Reno and co-author of the report, stressed the importance of these fish: “Freshwater fish support hundreds of millions of people around the world. For humans, they are very important.” He highlighted the diversity found within these species, which ranges from the massive piraíba, or giant catfish, to the long-distance migrating tropical eels of Oceania.
A Historic Review
The UN’s initial examination of migratory fish populations took place in 2011, assessing only 3,000 species. This latest evaluation, however, has expanded significantly, allowing for a more comprehensive understanding of the threats faced by these fish. The report identifies 325 species that need urgent monitoring and support under a global agreement aimed at protecting threatened migratory animals. Among these, 30 species have been marked as high priority, including those found within the UK, such as the Allis shad, river lamprey, brook lamprey, and Atlantic salmon.
Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, elaborated on the significance of these species: “For example, the golden mahseer is an iconic fish of the Himalayas. It’s called the tiger of the river, and many people in that region value it for cultural and spiritual practices that extend beyond economic interests.”
Overfishing and Habitat Loss
The threats facing these migratory fish are manifold. Overfishing and habitat destruction are primary concerns. Dams, which disrupt river systems, impede natural migration patterns, making it challenging for fish to access their spawning habitats. According to Thieme, “Habitat loss includes things like dams that fragment a river system, and can change the natural flow regime of a river.”
In Europe, the situation is particularly dire, with barriers to migration occurring on average every kilometre. Dr. Janina Gray, head of science at environment charity WildFish, pointed out the cumulative impact of these barriers: “It can have a massive impact in terms of the energy reserves fish are using to get over the barriers. This makes them more susceptible to disease and predation, and they often spawn in less than optimal conditions.”
The Path Forward
Addressing the plight of migratory fish requires international cooperation. These species often cross borders during their migrations, necessitating coordinated conservation efforts among governments. The UN’s Convention on the Conservation of Migratory Species, established in 1979, aims to foster such collaboration.
The UN is advocating for the inclusion of the 30 priority fish species in the treaty at its upcoming annual meeting in three years’ time. This move could mirror the success seen with the saiga antelope, which has rebounded from near extinction thanks to international conservation initiatives.
Amy Fraenkel, the UN Executive Secretary for the Convention, acknowledged the historical focus on more prominent species: “The focus has clearly been on some of the more well-known, more visible species, such as the big cats, on antelope, on whales, on dolphins. Now it is time for migratory freshwater fish to receive the attention they urgently need.”
Why it Matters
The decline of migratory fish not only threatens biodiversity but also jeopardises the food security and cultural practices of billions around the globe. Urgent action is required to protect these vital species and their habitats. If left unaddressed, the consequences will extend beyond the aquatic environment, impacting communities that depend on these fish for their livelihoods. The time for concerted global action is now; the survival of these species—and the people who rely on them—hangs in the balance.
