A recent report has unveiled a staggering decline in global migratory fish populations, prompting a united front for conservation efforts. With an alarming 81% drop in numbers over the past fifty years, these essential species, which traverse vast distances in search of breeding grounds, face unprecedented threats from dam constructions, pollution, and overfishing. The UN has now prioritised thirty flagship species, including the golden mahseer and goonch catfish, for urgent conservation action.
The State of Our Waters
In a comprehensive assessment involving over 15,000 freshwater migratory fish species, researchers have highlighted a critical situation for these aquatic inhabitants, which constitute about half of all fish species worldwide. The research underscores a long-overlooked crisis that impacts not only biodiversity but also the livelihoods of millions who depend on these fish for sustenance.
Dr. Zeb Hogan, a prominent biologist and co-author of the report from the University of Nevada, Reno, remarked, “Freshwater fish support hundreds of millions of people around the world, so for humans, they are very important.” He emphasised the need for immediate protective measures, noting the immense diversity and ecological significance of migratory fish. “Every shape and size of animal you can imagine,” he added, referencing the remarkable adaptations of these species, from the colossal piraíba, known for its impressive size, to the delicate tropical eels navigating vast oceans.
A Closer Look at Threats
The decline of migratory fish is multifaceted. Overfishing and habitat degradation are two pressing issues that threaten their survival. Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US and a contributor to the report, explained, “Habitat loss includes things like dams that 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 report highlights specific species, such as the iconic golden mahseer of the Himalayas, revered for its cultural and spiritual significance, yet grappling with the dual threats of overfishing and habitat loss. The goonch catfish, another species on the endangered list, has suffered from over-exploitation as rivers, like the Indravati, undergo developmental changes that disrupt their migratory patterns.
Barriers to Migration
In Europe, the situation is particularly dire, with fish facing barriers to their migratory routes on average every kilometre. Dr. Janina Gray, head of science at the environment charity WildFish, pointed out that even small structures like culverts and weirs can significantly impact fish populations. “The cumulative effect on migrating fish is enormous,” she warned, noting that increased energy expenditure to navigate these obstacles can lead to heightened vulnerability to disease and predation, as well as suboptimal spawning conditions.
The need for coordinated international efforts is critical, as many migratory species traverse national borders. The Convention on the Conservation of Migratory Species, established in 1979, aims to foster collaboration among countries to safeguard these vital species, and the UN is now proposing the inclusion of the thirty at-risk fish species in the treaty at its upcoming meeting in three years.
A Hopeful Future
The plight of migratory fish is not without precedent for recovery. The saiga antelope serves as a testament to the effectiveness of international conservation efforts. Following a catastrophic population decline in 2015, concerted anti-poaching measures led to a remarkable resurgence, with numbers now exceeding one million.
Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species, has stressed the need to shift focus towards less visible but equally important species like migratory fish. “The focus has clearly been on some of the more well-known, more visible species,” she stated, acknowledging the historical oversight of aquatic species in conservation discussions.
Why it Matters
The stark decline of migratory fish populations is a clarion call for immediate action. These species are not merely components of a balanced ecosystem; they are vital to the food security and cultural heritage of countless communities worldwide. Protecting migratory fish is not just an environmental necessity; it is an ethical obligation to ensure the survival of biodiversity that sustains human life. Without urgent intervention, we risk losing these magnificent fish—and the irreplaceable benefits they provide—to the tides of neglect and indifference.
