Freshwater fish that embark on remarkable journeys through rivers and lakes are facing unprecedented threats, leading to alarming declines in their populations. A recent UN report reveals that essential migratory species, such as the golden mahseer and goonch catfish, have been prioritised for conservation as their numbers have plummeted by an estimated 81% over the past fifty years. This urgent situation demands immediate action to safeguard the future of these vital fish and the ecosystems they inhabit.
A Disturbing Trend
Migratory fish, which account for half of all fish species, are now under immense pressure from a combination of overfishing, pollution, and habitat destruction. The findings of this report, compiled by a coalition of international scientists, highlight the urgent need for global conservation efforts. Dr. Zeb Hogan, a biology professor at the University of Nevada, Reno and co-author of the report, emphasised the critical role these fish play in supporting the livelihoods of millions. “Freshwater fish provide food for over 200 million people worldwide, making their conservation vital,” he stated.
The report assessed over 15,000 species and, for the first time, provided a comprehensive overview of the status of migratory fish since the UN’s initial evaluation in 2011, which only covered 3,000 species. The research identified 325 fish requiring monitoring and support under a global agreement, with 30 species flagged as immediate priorities—some of which are native to the UK, including the Allis shad and Atlantic salmon.
Key Threats to Survival
The decline of these species can be traced back to two main culprits: overfishing and habitat loss. Michele Thieme, deputy lead for freshwater initiatives at the World Wildlife Fund US, noted the cultural significance of many of these fish. The golden mahseer, revered in the Himalayas and dubbed the “tiger of the river,” is emblematic of the challenges faced by migratory species. Thieme explained that habitat destruction, particularly from dam construction, has severely disrupted migratory routes, preventing fish from reaching their spawning grounds.
In Europe, the situation is dire, with barriers obstructing fish migration every kilometre on average. Dr. Janina Gray, head of science at the environment charity WildFish, pointed out that even minor barriers can have substantial cumulative effects on fish populations. “These barriers drain the energy reserves of fish, increasing their vulnerability to disease and predation,” she warned.
A Global Response is Essential
Given the transboundary nature of migratory fish, coordinated international efforts are essential to tackle these threats. The Convention on the Conservation of Migratory Species (CMS), established in 1979, aims to promote cooperation among nations to protect migratory species. The UN plans to propose the addition of the 30 prioritised fish species to the treaty at its upcoming annual meeting in three years. This move aims to replicate the success seen with other species, such as the saiga antelope, which has rebounded remarkably due to international conservation efforts.
The UN’s Executive Secretary for the CMS, Amy Fraenkel, highlighted the need to shift focus toward often-overlooked migratory fish species. “While much attention has been given to larger, more visible species like big cats and whales, it is now time for migratory freshwater fish to receive the coordinated action they urgently need,” she asserted.
Why it Matters
The decline of migratory fish species is not merely an environmental issue; it poses a significant threat to global food security and biodiversity. As these fish populations dwindle, the communities that rely on them for sustenance and cultural practices are at risk of losing an irreplaceable resource. Protecting these species is crucial not only for maintaining ecological balance but also for ensuring that future generations can enjoy the rich biodiversity our planet has to offer. The time for action is now, as the fate of these vital creatures hangs in the balance.
