In a groundbreaking report, a coalition of international scientists has sounded the alarm over the alarming decline in migratory fish populations, revealing a staggering 81% decrease in numbers over the past fifty years. The United Nations has responded by prioritising thirty flagship species for urgent conservation, highlighting the critical role these fish play in both ecosystems and human livelihoods.
The Diminishing Tide of Migratory Fish
Migratory fish, known for their extensive journeys through rivers, lakes, and estuaries, are facing unprecedented threats from a combination of habitat destruction, pollution, and overfishing. Species such as the golden mahseer and goonch catfish are among those identified in a comprehensive assessment involving over 15,000 freshwater migratory fish—representing half of all fish species. The report underscores a long-ignored yet vital component of our natural world, stating that these fish are essential to the livelihoods of millions globally.
Dr. Zeb Hogan, a prominent biologist at the University of Nevada, Reno, and co-author of the report, emphasized their importance: “Freshwater fish support hundreds of millions of people around the world, making them invaluable. These species not only provide food for 200 million people but also boast a remarkable diversity that must be preserved.” He described the awe-inspiring characteristics of migratory fish, including those that can weigh over 650 pounds and traverse more than 7,000 miles.
Urgent Need for Action
The United Nations’ previous assessment of migratory fish dates back to 2011, when only 3,000 species were evaluated. The recent report’s broader scope allows for a more comprehensive understanding of the challenges facing these fish. From this analysis, researchers have flagged 325 species for inclusion in a global agreement aimed at monitoring and supporting threatened migratory animals. Among these, thirty species have been prioritised for immediate action, including the Allis Shad, River Lamprey, Brook Lamprey, and Atlantic Salmon, all of which are found in the UK.
The report highlights two primary threats to these fish: overfishing and habitat loss. Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, noted the cultural significance of species like the golden mahseer, revered in the Himalayas for its spiritual importance. Unfortunately, these fish face escalating pressures from fishing practices and habitat disruption, particularly from dams that fragment river systems.
The Barriers to Migration
Migration disruption is particularly acute in Europe, where fish encounter barriers every kilometre on average. These barriers often come in the form of redundant culverts or weirs that obstruct natural migration pathways. Dr. Janina Gray, head of science at the environmental charity WildFish, warned of the cumulative impact of these obstacles: “The energy reserves fish expend to navigate these barriers can lead to increased susceptibility to disease and predation, as well as spawning in less than optimal conditions.” The consequences are dire, with entire populations at risk unless immediate action is taken.
A Coordinated Global Response
Many migratory fish traverse international borders, necessitating cooperation among nations to address the multifaceted threats they face. Prof. Hogan reiterates the need for a collaborative approach, stating that “coordinated efforts between governments are essential to ensure the recovery of these national stocks.” The UN aims to include the thirty species in the Convention on the Conservation of Migratory Species at its annual meeting in three years, fostering a united front for their protection.
The Saiga antelope serves as a testament to the effectiveness of international conservation efforts. After a devastating mass die-off in 2015, a concerted anti-poaching initiative saw their population rebound to over a million. Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species, has called for a similar focus on migratory freshwater fish, which have historically been overshadowed by more charismatic species like big cats and whales.
Why it Matters
The plight of migratory fish is not merely an environmental concern; it is a pressing issue that resonates with the livelihoods of millions who depend on these species for sustenance and economic stability. As their numbers dwindle, so too does the delicate balance of our ecosystems. The proposed conservation measures represent a crucial step towards safeguarding not only these remarkable species but also the health of our planet and the communities that rely on them. The time for action is now, and the call for a global commitment to protect these fish is more urgent than ever.
