Recent findings reveal alarming declines in migratory fish populations, with an estimated 81% drop over the past fifty years. This decline is primarily attributed to habitat destruction, pollution, and overfishing, significantly jeopardising the future of these vital species. The United Nations has prioritised 30 flagship species for conservation, underscoring the pressing need for coordinated global efforts to protect them.
A Troubling Assessment of Freshwater Fish
A comprehensive study led by international scientists has evaluated over 15,000 species of freshwater migratory fish, which constitute approximately half of all fish species. The report indicates that many of these fish are facing severe threats that hinder their ability to reach breeding grounds. Among the species highlighted are the golden mahseer and goonch catfish, both of which are emblematic of the urgent need for conservation measures.
Dr. Zeb Hogan, a professor of biology at the University of Nevada, Reno, and co-author of the report, emphasises the significance of migratory fish to global livelihoods. “Freshwater fish support hundreds of millions of people worldwide, providing food for over 200 million individuals,” he stated. “Their immense diversity is something that must be protected.”
The Need for Global Collaboration
The UN’s previous assessment of migratory fish populations was conducted in 2011, involving only 3,000 species. The current report has significantly expanded this scope, revealing that 325 fish require urgent inclusion in a global monitoring agreement aimed at safeguarding threatened migratory species. Among the identified priority species are several found in the UK, such as the Allis Shad, River Lamprey, Brook Lamprey, and Atlantic Salmon.
The report highlights the dual threats of overfishing and habitat loss. Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, elaborates on the plight of the golden mahseer, revered in the Himalayas for its cultural importance. “It faces significant challenges from both overfishing and habitat destruction, which includes the fragmentation caused by dams,” she explained.
Barriers to Migration: An Ongoing Crisis
In Europe, migratory fish encounter barriers every kilometre, exacerbating their plight. These obstacles often consist of outdated culverts or weirs that could be dismantled to restore natural migration routes. Dr. Janina Gray, head of science at the environment charity WildFish, notes that the cumulative effect of these barriers is detrimental. “The energy reserves fish expend to overcome these obstacles make them more vulnerable to disease and predation, as well as leading to suboptimal spawning conditions,” she remarked.
To facilitate the recovery of these species, international cooperation is essential. As Prof. Hogan points out, many migratory fish traverse national borders, necessitating a unified approach to conservation efforts. The Convention on the Conservation of Migratory Species, a global treaty established in 1979, requires member countries to collaborate in protecting migratory species.
The UN is advocating for the inclusion of the 30 prioritised fish species in this treaty during its next annual meeting in three years. This initiative echoes the success of other conservation efforts, such as those that have revived the saiga antelope population after a dramatic decline.
Why it Matters
The decline of migratory fish populations is not merely an environmental concern; it has profound implications for food security, biodiversity, and the cultural heritage of communities reliant on these species. As ecosystems become increasingly fragmented and threatened, the urgency for coordinated global conservation efforts becomes undeniable. Protecting these vital species is critical not only for maintaining healthy aquatic ecosystems but also for ensuring the livelihoods of millions who depend on them. The time for action is now.
