In a stark warning for biodiversity and food security, a recent United Nations report highlights a dramatic decline in freshwater migratory fish populations, revealing an alarming 81% decrease over the past fifty years. The findings underscore the urgent need for conservation efforts as key species, including the golden mahseer and goonch catfish, face existential threats from habitat destruction, pollution, and overfishing.
A Global Crisis for Freshwater Species
The plight of migratory fish—those that traverse vast distances across rivers, lakes, and oceans—is now a pressing global concern. According to a comprehensive study involving over 15,000 species of freshwater fish, these aquatic animals are not only critical for ecosystems but also integral to the livelihoods of millions globally. Dr. Zeb Hogan, a prominent biologist and co-author of the report from the University of Nevada, Reno, emphasised their importance, stating, “Freshwater fish support hundreds of millions of people around the world, so for humans, they’re very important.”
The report, the first of its kind since 2011, has identified 325 fish species that require urgent protection, with thirty being flagged as immediate priorities. Among these are several species indigenous to the UK, such as the Allis shad and Atlantic salmon.
Overfishing and Habitat Loss: The Twin Threats
Many of the species highlighted in the report are not only vital for their ecological roles but also hold cultural significance for various communities. Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, explained the dual challenges of overfishing and habitat loss. “The golden mahseer, an iconic fish of the Himalayas, is facing threats that extend beyond economic value, encompassing cultural and spiritual practices,” she noted.
Habitat loss, particularly due to the construction of dams, disrupts the natural flow of rivers, preventing fish from accessing their spawning grounds. “Dams fragment river systems and change the natural flow regime, which results in fish not being able to connect to their spawning habitats,” Thieme added. This disruption is particularly acute in Europe, where fish encounter barriers every kilometre on average, significantly taxing their energy reserves and making them more vulnerable to disease and predation.
The Need for Coordinated Global Action
Dr. Janina Gray, head of science at WildFish, highlighted how even small barriers like culverts can have a cumulative detrimental effect on migrating fish. “The energy reserves fish use to overcome these barriers can lead to massive impacts on their health and reproductive success,” she warned.
The report calls for a concerted effort among nations to address these challenges. The Convention on the Conservation of Migratory Species, a UN treaty established in 1979, necessitates collaboration between countries to ensure the protection of migratory species. The UN is now advocating for the inclusion of the thirty priority species in the treaty during its upcoming annual meeting in three years.
Learning from Past Successes
Conservation efforts for other species have shown promise, with the saiga antelope’s recovery serving as a beacon of hope. After a catastrophic mass die-off in 2015, international initiatives successfully revived the population to over a million. Amy Fraenkel, Executive Secretary for the Convention on Migratory Species, noted, “The focus has clearly been on some of the more well-known species, such as big cats and whales. Now it is time for migratory freshwater fish to receive similar coordinated action.”
The pressing need for comprehensive strategies to protect these species is underscored by the fact that they play an essential role in maintaining the health of aquatic ecosystems and providing food security for communities worldwide.
Why it Matters
The decline of migratory fish populations is not merely an environmental issue; it poses a significant threat to global food security and the livelihoods of millions who depend on these species. As biodiversity dwindles, the interconnectedness of ecosystems falters, leading to potentially catastrophic consequences not only for fish populations but also for human communities reliant on them. Urgent action is required to safeguard these vital species before it is too late.
