A recent report highlights the alarming decline of migratory fish populations worldwide, prompting urgent calls for conservation efforts. The United Nations has identified 30 flagship species, including the golden mahseer and goonch catfish, as priorities for protection. With assessments indicating an estimated 81% decrease in migratory freshwater fish over the past 50 years, the need for coordinated international action has never been more critical.
The Plight of Migratory Fish
Fish species that undertake extensive migrations through rivers, lakes, and other waterways are increasingly jeopardised by a combination of factors, including dam construction, pollution, and overfishing. These obstacles hinder their ability to reach essential breeding grounds, threatening both their populations and the livelihoods of millions who depend on them.
A comprehensive study conducted by a coalition of international scientists evaluated over 15,000 freshwater migratory fish species, revealing a stark decline in numbers. Dr. Zeb Hogan, a co-author of the report and a biology professor at the University of Nevada, Reno, emphasised the significance of these fish, stating, “Freshwater fish support hundreds of millions of people around the world, so for humans, they’re very important.” He highlighted the remarkable diversity within migratory species, which range from the massive piraíba catfish, capable of migrating over 7,000 miles, to the intricately patterned golden dorado of South America.
Conservation Priorities
This report marks a significant expansion of the UN’s previous assessment from 2011, which only considered 3,000 species. With the current findings, the International Union for the Conservation of Nature (IUCN) has identified 325 fish requiring urgent monitoring under global conservation agreements. Among these, 30 species have been designated as high-priority for immediate action, including several found in the UK, such as the Allis shad, River lampry, Brook lamprey, and Atlantic salmon.
The report also underscores the cultural and spiritual significance of certain species. Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, notes the golden mahseer as an iconic fish of the Himalayas, revered for its cultural importance. Yet, these fish face dual threats from overfishing and habitat degradation, which disrupt their natural migration routes.
Barriers to Migration
One of the most pressing challenges facing migratory fish in Europe is the prevalence of barriers such as dams and weirs, which obstruct their routes. Dr. Janina Gray, head of science at the environmental charity WildFish, pointed out that these barriers exist on average every kilometre (0.6 miles), imposing significant energy costs on fish attempting to navigate them. This not only increases their susceptibility to disease and predation but also leads to spawning in suboptimal conditions, further exacerbating population declines.
Collaborative Conservation Efforts
Many migratory fish species traverse international borders, underscoring the necessity for cooperative conservation strategies among nations. The Convention on the Conservation of Migratory Species, a UN treaty established in 1979, aims to facilitate such collaboration. As part of ongoing efforts, the UN is advocating for the inclusion of the identified 30 fish species in the treaty during its next annual meeting in three years.
Examples from other species, like the saiga antelope, illustrate the potential for successful recovery through international cooperation. After facing a devastating decline, targeted anti-poaching initiatives have helped the saiga population rebound to over a million individuals. According to Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species, it is now time to extend similar efforts to the realm of migratory freshwater fish, which have historically received less attention than more prominent species like big cats and whales.
Why it Matters
The drastic decline in migratory fish populations poses a profound threat not just to biodiversity but to the ecological health of freshwater systems globally. These fish are vital for maintaining aquatic ecosystems and supporting the livelihoods of millions. The urgent call for international collaboration to protect these species is not merely an environmental issue; it is a pressing human concern that intersects with food security, cultural heritage, and the sustainability of natural resources. The time for action is now, as failure to address these challenges could lead to irreversible consequences for both migratory fish and the communities that rely on them.
