In a stark revelation, a recent UN report highlights the alarming decline of migratory fish populations, with a staggering 81% drop over the past fifty years. This decline poses a significant threat to both biodiversity and the livelihoods of millions who depend on these species for sustenance. Among the 15,000 species evaluated, thirty have been identified as urgent priorities for global conservation efforts, necessitating immediate action to safeguard their future.
A Global Crisis for Freshwater Fish
Freshwater fish are not just integral to ecosystems; they are vital for the survival of hundreds of millions of people worldwide. Dr. Zeb Hogan, a co-author of the report and a professor of biology at the University of Nevada, Reno, underscores their importance, stating, “Freshwater fish support hundreds of millions of people around the world, so for humans, they’re very important.” These migratory species, including the golden mahseer and the goonch catfish, are facing a perfect storm of threats: habitat destruction, pollution, and relentless overfishing.
The report marks a significant expansion of the UN’s focus on these fish, which began in 2011 with the assessment of only 3,000 species. This time, the International Union for the Conservation of Nature (IUCN) has expanded its data collection efforts, revealing the dire state of migratory freshwater fish populations. Among the 325 species identified for monitoring, thirty have been highlighted as top priorities for conservation, including notable species found in the UK such as the Allis Shad, River Lamprey, and Atlantic Salmon.
The Dual Threat of Overfishing and Habitat Loss
Many of the fish species on this priority list are not just ecologically significant but also hold cultural importance. Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, explains the plight of the golden mahseer, revered as the “tiger of the river” in the Himalayas. “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 notes. Unfortunately, this iconic fish is facing severe threats from both overfishing and habitat degradation.
Habitat loss, often exacerbated by the construction of dams, disrupts the natural flow of rivers and prevents fish from accessing their breeding grounds. Thieme explains, “Dams fragment a river system, and can change the natural flow regime of a river, which results in fish not being able to connect to their spawning habitats.” The consequences are dire: populations dwindle, and the balance of ecosystems is thrown into disarray.
Barriers to Migration and the Need for Coordination
The disruption of migratory routes is particularly pronounced in Europe, where barriers such as small culverts and weirs impede fish movement at an alarming frequency—every kilometre on average. Dr. Janina Gray, head of science at the environmental charity WildFish, warns of the cumulative impact these barriers create. “It can have a massive impact in terms of the energy reserves fish are using to get over the barriers. That makes them more susceptible to disease and reduces their chances of spawning in optimal conditions.”
Addressing these challenges requires coordinated action across borders. As Prof. Hogan asserts, “Most species will cross country borders on their mammoth migrations. This requires coordinated efforts between governments to tackle these threats and ensure the recovery of national stocks.” The UN’s Convention on the Conservation of Migratory Species, established in 1979, is now being called upon to expand its scope to include these threatened fish species.
A Path Forward: The Role of International Agreements
The UN is advocating for the inclusion of these thirty fish species in the treaty during its upcoming annual meeting in three years’ time. This move echoes the successful recovery of other species like the saiga antelope, which rebounded from the brink of extinction thanks to international conservation efforts. Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species, acknowledges the historical focus on more charismatic species but insists it is time for migratory freshwater fish to receive the attention they desperately need.
The growing recognition of the plight of these fish is a hopeful sign, but the urgency of the situation cannot be overstated. As the report illustrates, the survival of migratory fish is intertwined with the health of our ecosystems and the well-being of human communities.
Why it Matters
The decline of migratory fish species signifies a broader environmental crisis that impacts not only aquatic ecosystems but also the livelihoods of countless individuals worldwide. Protecting these fish is not merely about preserving biodiversity; it is about ensuring food security and cultural heritage for millions. As we face unprecedented environmental challenges, the time to act is now. The fate of these remarkable species—and the ecosystems they inhabit—hangs in the balance, demanding our immediate attention and concerted action.
