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An alarming new report from the United Nations reveals a staggering decline in migratory fish populations, with an estimated 81% drop over the past 50 years. This dramatic decrease is primarily attributed to the combined threats of habitat destruction, pollution, and overfishing, which hinder these species from reaching vital breeding grounds. Among the 15,000 freshwater migratory fish species assessed, the golden mahseer and goonch catfish have been highlighted as priority species for urgent conservation efforts.
The Plight of Migratory Fish
Migratory fish, such as the majestic Atlantic tarpon, traverse vast distances along coastlines, yet their numbers are dwindling as essential mangrove habitats face degradation. Freshwater fish are not merely ecological marvels; they are integral to the livelihoods of millions worldwide. Dr. Zeb Hogan, a prominent biologist and co-author of the report, emphasises their importance: “Freshwater fish support hundreds of millions of people around the world, so for humans, they’re very important.” These fish provide sustenance for over 200 million individuals globally and display a remarkable diversity that must be safeguarded.
The UN’s latest assessment marks a significant advancement from previous evaluations conducted in 2011, which only encompassed 3,000 species. The breadth of this new research allowed for comprehensive insights into the status of migratory fish, leading to the identification of 325 species in need of monitoring and conservation. Notably, 30 of these species have been designated as priorities, including several found in the UK, such as the Allis shad and Atlantic salmon.
Overfishing and Habitat Loss: The Dual Threats
The report highlights two primary threats affecting migratory fish: overfishing and habitat loss. Michele Thieme, deputy lead for freshwater at the World Wildlife Fund US, notes the cultural significance of species like the golden mahseer, revered in the Himalayas for its spiritual value. However, these fish are under siege from intense fishing pressures and the destruction of their habitats.
“Habitat loss includes things like dams that fragment a river system and can change the natural flow regime of a river, resulting in fish being unable to connect to their spawning habitats,” Thieme explains. The impact of such disruptions can be catastrophic, leading to population declines and threatening the very existence of these species.
The European Context: Barriers to Migration
In Europe, migratory fish face a particularly challenging landscape, where barriers litter their migratory routes. On average, fish encounter an obstruction every kilometre, which includes redundant culverts and weirs. Dr. Janina Gray, head of science at WildFish, stresses the cumulative impact these barriers have on fish populations. “It can have a massive impact in terms of the energy reserves fish are using to get over the barriers,” she warns. This added stress makes them more vulnerable to diseases and predation, ultimately affecting their spawning success.
The complexities of international migration necessitate a coordinated approach among governments to alleviate these dangers. The Convention on the Conservation of Migratory Species, established in 1979, aims to promote collaborative efforts to protect migrating species across borders. The UN is now advocating for the inclusion of the 30 identified fish species in this treaty, a move that could significantly bolster their chances for recovery.
Success Stories and Hope for the Future
Historically, conservation efforts have tended to focus on more charismatic species, such as large mammals and marine mammals, often overshadowing the plight of migratory fish. However, the UN’s renewed focus on these aquatic species is a welcome shift. Amy Fraenkel, the Executive Secretary for the Convention on Migratory Species, points to success stories like the saiga antelope, which, after facing near extinction, has seen its numbers rebound following concerted conservation action. “It is now the turn of migratory freshwater fish to benefit from coordinated action,” she asserts.
The UN’s proposal to add the 30 priority species to the treaty at its next meeting in three years represents a critical opportunity for these fish. The international community must now rally to ensure that these vital species receive the protection they urgently require.
Why it Matters
The decline of migratory fish populations is not merely an environmental issue; it threatens the very fabric of ecosystems and the communities that rely on them. With a staggering 81% reduction in numbers, urgent action is imperative to reverse this trend and safeguard the future of these species. Our commitment to conservation today will determine the health of our waterways and the livelihoods of countless individuals tomorrow. As we face an increasingly uncertain environmental future, it is our responsibility to protect these remarkable creatures that play a crucial role in maintaining biodiversity and supporting human life.
