A recent report from the United Nations has unveiled a staggering decline in migratory fish populations, with estimates showing an alarming 81% drop over the past fifty years. This decline is attributed to a trifecta of threats: habitat destruction, pollution, and overfishing. As a result, 30 key species, including the golden mahseer and goonch catfish, have been designated as priorities for global conservation efforts.
The State of Migratory Fish
Fish species that travel vast distances through rivers, lakes, and other waterways are vital not only for biodiversity but also for the livelihoods of countless communities worldwide. According to Dr. Zeb Hogan, a professor of biology at the University of Nevada, Reno, migratory freshwater fish are crucial, supporting the nutritional needs of approximately 200 million people globally. He highlights the remarkable diversity of these fish, some capable of migrating over 7,000 miles and weighing up to 650 pounds.
The UN’s assessment, which evaluated over 15,000 species of freshwater migratory fish, marks a significant expansion from previous studies, which only considered around 3,000 species in 2011. This comprehensive review has led to the identification of 325 species that require monitoring and protection, with 30 selected as urgent priorities. Among these are several species native to the UK, such as the Allis shad, River lamprey, and Atlantic salmon.
Overfishing and Habitat Loss: The Dual Threats
The plight of these migratory fish is exacerbated by two significant challenges: overfishing and habitat degradation. Michele Thieme, deputy lead for freshwater conservation at WWF US and a contributor to the report, stresses the cultural and spiritual significance of species like the golden mahseer, often referred to as the “tiger of the river.” However, it is under severe threat from overfishing and the loss of natural habitats, particularly due to the construction of dams that disrupt river ecosystems.
Thieme elaborates on the impact of such developments: “Dams fragment river systems and alter natural flow patterns, preventing fish from accessing essential spawning habitats.” This disruption is particularly pronounced in Europe, where migrating fish encounter barriers every 0.6 miles on average. Dr. Janina Gray, head of science at environment charity WildFish, warns that these barriers, often small and redundant, have a cumulative effect that can drain fish of their energy reserves, making them more vulnerable to diseases and predation.
Collaborative Efforts for Conservation
Addressing these threats requires a concerted response from governments across national borders. As many migratory fish species traverse multiple countries during their life cycles, international cooperation is essential for effective conservation strategies. The Convention on the Conservation of Migratory Species, an established UN treaty, is poised to play a crucial role. The UN plans to propose the inclusion of these 30 priority fish species in the treaty at its next annual meeting in three years.
The success of international conservation efforts can be seen in the recovery of the saiga antelope, which rebounded from near extinction following collaborative anti-poaching initiatives. Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species, emphasises that it is now time for migratory freshwater fish to receive similar attention and action.
Why it Matters
The dramatic decline of migratory fish populations is not just an environmental issue; it poses a direct threat to food security, cultural heritage, and economic stability for millions of people worldwide. The urgency of the situation calls for immediate action to safeguard these species for future generations. Without intervention, we risk losing not only the fish themselves but also the intricate ecosystems and communities that rely on them. The time to act is now; our rivers, lakes, and oceans depend on it.
