Large animal migrations usually evoke wildebeest images crossing the African savanna or flocks of birds crossing the continental skies. However, beneath the surface of our rivers and lakes lies an epic journey that is about to disappear. Here the UN itself pointed out that the populations of migratory fish of freshwater have fallen by 81% in the last half century.
An abyss of data. Data published by the UN with support from WWF and Wetlands they point to a major collapse of the fish population. And to understand the magnitude of the problem, the researchers analyzed 1,864 populations of 284 species of migratory fish between 1970 and 2020. Here the overall result was the loss of that 81% of biomass with a panorama that changes depending on where we look.
This is why Latin America and the Caribbean is the most affected region, with a terrifying decrease of 91% of its populations, while in Europe the collapse is 75%.
A conservation paradox. A very important fact is that 97% of migratory fish that are already on the CMS protection list are threatened with extinction. However, science indicates that there is 325 species candidates (and long forgotten) that urgently need to be included in the appendices of international protection to survive. Brazil, for example, is already promoting the protection of emblematic species such as the painted surubí so that its delicate situation is recognized.
Because? Migratory fish, such as salmon or sturgeon, need to swim hundreds or thousands of kilometers to reproduce or feed, using what scientists have baptized such as Global Swimways, or global navigable waterways. In this way, one of the reasons that is causing this great change is the fragmentation of the habitat, since the massive construction of dams and artificial barriers has cut off these ‘highways’. So if a fish can’t make it up the river to spawn, its lineage ends there.
Other reasons are found in overexploitation, since unsustainable fishing continues to decimate adult populations before they can reproduce. But we cannot forget about pollution either, since agricultural, industrial and urban discharges have degraded water quality to toxic levels for many of these sensitive species.
It has consequences. Environmental organizations here point out that the disappearance of these animals is not only a zoological tragedy, since migratory fish are a fundamental pillar of food security. In the end, tens of millions of people around the world depend on these animals and we cannot forget that they are the ecological engine that keeps the rivers themselves alive.
That is why the message that the scientific community leaves us is an ultimatum: we must restore the connectivity of our rivers to protect the remaining migratory routes, or we will face the imminent extinction of some fascinating species.
Images | Jinomono Media
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