The migration of fish

For many media, April is World Fish Migration Day. In reality this is not the case, but talking about it is never a mistake. In fact, migratory fish populations around the world are in rapid decline, mainly due to dams and other artificial barriers that block flows and hinder migration. But the solution is there, and it’s called ecosystem restoration.


The conservation of fish species, especially those of river habitats, is rarely at the center of public attention as are far more charismatic species such as large mammals. Yet in the last 50 years alone, over 70% of the world’s populations of migratory fish have experienced a rapid and seemingly unstoppable decline, leading to the extinction of numerous species. In fact, there are many species of fish that migrate, and many of these pass from a marine environment to the freshwater one of rivers to complete their life cycles. It is estimated that over a thousand declining migratory species are in need of protection.


For example, salmon, which starting from the sea go up the rivers as the last act of their existence: reproduction. Those who live in the sea to reproduce in rivers are called anadromous. Conversely, those who spend most of their lives in fresh water to reproduce in seas and oceans are called catadromous. Among these there are also eels (Anguilla anguilla and Anguilla rostrata), a species now almost one step away from extinction in nature.


Many of these fish make extraordinary journeys that can be up to 10 thousand kilometers long. To orient themselves along the way, they use all their incredible skills: they navigate following the currents, perceive magnetic fields and even use their sense of taste and smell to find their way home.


The importance of these species also has a fundamental social and economic implication. In fact, there are billions of people in the world who directly or indirectly depend on these fish for food, sport, research and all other collateral activities related to these species and their ecosystems. For about a billion people, these fish are the main source of food and sustenance. Their decline, therefore, is putting at risk not only the health of ecosystems but also the survival of entire human populations.


The causes and possible solutions of the emergency


The main causes of the decline in migratory fish populations are attributable to the construction of artificial barriers in rivers which, by blocking migration routes, contribute to habitat degradation and loss and hinder reproduction. Embankments, barriers and above all dams alter the natural flow of waterways, physically preventing species such as salmon, eels and sturgeons from completing their migrations. In Europe alone, there are more than a million barriers that are certainly destined to increase, also in response to the climate emergency we are experiencing. But the solution exists, and it is also very effective: it is called restoring rivers and ecosystems.


The “simple” elimination of barriers, with the natural restoration of the rivers, has already proved to be the quickest and most effective way to encourage the recovery of migratory fish populations. Where the old disused dams have been eliminated, the fish have returned, and everyone has benefited from it. Ecosystems have recovered, populations have increased and sea fishing has grown.


About 25% of the barriers blocking rivers are now old or no longer in operation, and should be removed or restored. Eliminating them could be much easier and more advantageous from all points of view, from the environmental to the economic one. On the other hand, it is Europe itself that asks us for it, which with the Biodiversity Strategy of 2030 has set itself the ambitious goal of restoring the natural course of rivers for at least 25 thousand kilometers.


One of humanity’s most important challenges in response to the severe environmental and social crises we are experiencing is no longer the simple protection of the remaining natural areas, but the restoration and restoration of lost habitats and ecosystems. This is the great goal of the World Fishing Migration Foundation, to raise awareness and inspire people to have free rivers to flow and support biodiversity, ecosystems and fishing. Salvatore Ferraro Add a comment! The dog (Canis lups familiaris) Today is the International Day of Forests Migratory birds and the promise of return The greatest spectacle on Earth: migration The dog’s routine, how to better organize the day Tales of animal aesthetics and strange fish

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