The survival of migratory fish species is under grave threat, with recent findings revealing a staggering 81% decline in their populations over the past fifty years. This alarming situation, highlighted in a new report by the United Nations, underscores the urgent need for concerted conservation efforts to safeguard these critical aquatic species, many of which play a vital role in the livelihoods of hundreds of millions worldwide.
A Global Crisis for Migratory Fish
Fish that undertake extensive migrations through freshwater systems are facing unprecedented challenges. Dams, pollution, and rampant overfishing are combining to obstruct their paths to breeding grounds, leading to a drastic reduction in their numbers. Notable species such as the golden mahseer and goonch catfish have been flagged by the UN as priority candidates for global conservation efforts. These findings stem from an extensive review conducted by a team of international scientists, who assessed over 15,000 species of freshwater migratory fish, a group that constitutes half of the world’s fish species.
Dr. Zeb Hogan, a co-author of the report and a professor of biology at the University of Nevada, Reno, emphasised the critical role these fish play in ecosystems and human diets. “Freshwater fish support hundreds of millions of people around the world, so for humans, they’re very important,” he asserted. He further noted that these migratory species not only provide sustenance for approximately 200 million people globally but also exhibit remarkable diversity deserving of protection.
Increased Awareness and Action
The UN’s initial assessment of migratory fish populations dates back to 2011, when only 3,000 species were evaluated. Since then, the International Union for the Conservation of Nature (IUCN) has worked diligently to gather more comprehensive data. The latest report identifies 325 fish species that require urgent monitoring and support under a global agreement aimed at protecting migratory animals. Among these, 30 species have been prioritised, including several that inhabit UK waters, such as the Allis Shad, River Lamprey, Brook Lamprey, and Atlantic Salmon.
Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US and a contributor to the report, explained the cultural significance of several of the highlighted species. For instance, the golden mahseer is revered in the Himalayas, often referred to as the “tiger of the river” and holds deep cultural and spiritual value for local communities. Unfortunately, both overfishing and habitat destruction, primarily due to damming and river system fragmentation, pose significant threats to these iconic fish.
The Impact of Barriers on Migration
In Europe, the disruption of migratory routes is particularly acute, with fish encountering barriers such as small culverts or weirs approximately every kilometre (0.6 miles). Dr. Janina Gray, head of science at the environmental charity WildFish, highlighted the cumulative impact of these obstructions. “The energy reserves fish expend overcoming these barriers make them more susceptible to disease and predation, and they often spawn in suboptimal conditions,” she warned.
To effectively address these challenges, coordinated international action is essential. Migratory fish species often traverse national borders, necessitating cooperation among governments to ensure their recovery. The 1979 Convention on the Conservation of Migratory Species, a UN treaty, aims to facilitate such collaboration. The UN is now advocating for the inclusion of the 30 identified fish species into this treaty at its upcoming annual meeting in three years.
Learning from Past Successes
Instances of successful conservation provide hope for migratory fish. The saiga antelope, for example, rebounded from a precarious situation following a mass die-off in 2015, thanks to the establishment of an international anti-poaching team. Today, saiga populations have surged to over a million. “The focus has clearly been on more visible species, such as big cats and marine mammals,” noted Amy Fraenkel, the UN Executive Secretary for the Convention on Migratory Species. “Now, it’s time to shine a light on migratory freshwater fish and galvanise action.”
Why it Matters
The plight of migratory fish is not just an environmental concern; it is a pressing socio-economic issue. These species are integral to the well-being of countless communities around the globe, providing food and supporting livelihoods. As their populations dwindle, the ripple effects could threaten food security and disrupt the delicate balance of aquatic ecosystems. Urgent action is needed now to avert a further decline and ensure the survival of these vital fish populations for future generations.
