In a startling new report, scientists have revealed that migratory fish populations worldwide have plummeted by an alarming 81% over the past 50 years, primarily due to human activities such as pollution, overfishing, and habitat destruction. This drastic decline has prompted the United Nations to prioritise the conservation of thirty key fish species, including the golden mahseer and the goonch catfish, which are now at the forefront of global conservation efforts.
A Troubling Overview of Migratory Fish
The report, compiled by a team of international researchers, assessed over 15,000 species of freshwater migratory fish—representing half of all fish species. The findings highlight a critical situation for these species, which are essential not only for ecological balance but also for the livelihoods of millions of people globally. Dr. Zeb Hogan, a biology professor at the University of Nevada, Reno and co-author of the report, stressed the importance of these fish, stating, “Freshwater fish support hundreds of millions of people around the world, so for humans, they’re very important.”
Many migratory species are integral to the diets of approximately 200 million individuals, illustrating their role in global food security. Hogan noted the remarkable diversity among these fish, from the massive piraíba catfish, which can weigh over 295 kg, to the vibrant golden dorado that undertake extensive migrations across South America.
The Call for Conservation
The UN’s renewed focus on migratory fish follows a previous assessment in 2011, which only evaluated 3,000 species. The current report has revealed the desperate need for conservation efforts as 325 species have been identified for inclusion in global agreements aimed at monitoring and supporting threatened migratory animals. Among the thirty priority species highlighted are several found in the UK, including the Allis shad, River lamprey, Brook lamprey, and Atlantic salmon.
Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, explained the significance of the golden mahseer, often referred to as the “tiger of the river.” It holds immense cultural and spiritual importance in the Himalayas, yet it faces severe threats from overfishing and habitat loss.
The Impact of Human Activity
The threats to migratory fish are compounded by issues such as dam construction, which fragments river systems and disrupts the natural flow essential for spawning. Dr. Janina Gray, head of science at the environment charity WildFish, highlighted that in Europe alone, fish encounter barriers on average every kilometre, making their migratory journeys increasingly treacherous.
These disruptions not only affect the ability of fish to spawn but also compromise their health and vitality, leading to increased susceptibility to disease and predation. As populations dwindle, the ecological ramifications extend beyond the fish themselves, threatening entire aquatic ecosystems.
Framework for Future Conservation
The UN is advocating for the inclusion of these thirty fish species in the Convention on the Conservation of Migratory Species, a global treaty established in 1979 that encourages international cooperation for the protection of migratory species. The next annual meeting of the convention, scheduled in three years, will serve as a crucial platform for advancing this initiative.
The success of conservation efforts can be seen in the recovery of other species, such as the saiga antelope, which rebounded from near extinction due to coordinated international anti-poaching efforts. Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species, emphasised that it is now time to turn attention to migratory freshwater fish, which have historically been overshadowed by more charismatic species.
Why it Matters
The decline of migratory fish populations signals a broader ecological crisis that could have far-reaching implications for biodiversity and human livelihoods. As these fish are vital for maintaining healthy aquatic ecosystems and supporting millions of people, urgent action is required to reverse their fortunes. The proposed conservation measures are not merely about saving fish; they are about safeguarding the delicate balance of our freshwater environments and ensuring that future generations can benefit from these invaluable resources.
