Ana Tuñas Matilla |
Navarra (EFE).- Renaturalizing rivers by removing obstacles created by man is essential to strengthen the habitat of the species that live in them, especially migratory fish that, like salmon, must overcome weirs or dams, many of them in disuse, to complete their life cycle.
With the aim of improving the state of rivers that run between Spain and France, Life Kantauribai was born, a project co-financed with European funds that will act in five basins of the Bay of Biscay: Oria and Urumea, between Navarra and Guipúzcoa; Nive and Nivelle, between Aquitaine and Navarra, and Bidasoa, shared by all three.
River restoration will mainly consist of recovering the longitudinal continuity of rivers by removing disused dams and building fish passages in those that cannot be demolished.
In parallel, they will work with native species, with a focus on fish that migrate between the sea and the river; the location of live specimens of river mussels and the improvement of populations of mammals such as the European mink and the Iberian desman. In addition, they will eradicate exotics such as the coypu and the American mink.
The situation of these native species is “compromised” and it is necessary to improve their habitat and their state of conservation, according to Josu Elso, a specialist in fish management at Gestión Ambiental de Navarra (GAN).
“We hope that thanks to the project it will be possible to improve the size of these populations”, according to the expert, who has warned that the bad situation in which they find themselves is caused, almost always, by “the misuse we make of the rivers humans”.
“For decades, we have been using the river’s resources without thinking about biodiversity and that has led us to create many dams, to extract a lot of water, and this has had negative consequences that in the long term have led these species to be in the situation they are in.”
Knock down 25 obstacles
To partially reverse the fragmentation of the rivers and, therefore, the poor situation of the species, they will demolish 25 dams or dams and make another seven permeable.
With the demolition, in addition to facilitating the transit of migrating fish, the sediments that are now retained by the dams will be able to travel downstream, restoring part of the river to its original morphology, according to the head of hydraulic works of the Basque Water Agency (URA). ), Aitziber Urquijo.
The permeabilization will consist of installing passage ramps for the fish and will be carried out in dams that cannot be demolished because there is a valid concession, for example, for hydroelectric use; because they have become a patrimonial asset, for social reasons or for technical reasons.
Among the dams on which they will act, the one of the Artikutza reservoir stands out, the largest in Spain to have been emptied and which represents an engineering and environmental challenge.
automated tracking
In addition to improving their habitat, Kantauribai’s objective is to find out the real situation of species such as salmon, lamprey or shad, and to find live specimens of river mussels, explained the head of the Fluvial Environment Section of the Department of Rural Development. and Environment of Navarra, José Ardaiz.
To control the fish, they will replace the current sampling system, based on the handling of specimens that are captured and anesthetized for study and later released, by the use of underwater cameras that will allow them to be identified and analyzed without the need to touch them, thus eliminating stress. that this generates.
In order to try to locate live specimens of river mussels (of which they have only found remains of dead specimens), they will carry out samplings based on environmental DNA to establish in which areas they could be found and track them with the help of mirafundos.
“It is important to have data on the fish populations because that way we can assess how they are doing in the future. In the case of salmon, the global trend is that it is not having a good time, climate change conditions do not favor a species that likes fresh water.”
“This allows us to be a kind of alarm. If the fish populations that live in our rivers are having a hard time, something is happening and we have to try to remedy it (…). With projects like this we can improve the health of our rivers, which in the end is our own health”.
Help the Iberian desman and European mink
As for mammals, they will focus on improving the populations of two native species in a critical situation: Iberian desman and European mink; and in reducing those of two invaders: coypu and American mink, according to the expert from the Wildlife Service of the Guipúzcoa Provincial Council Aitor Lekuona.
These two invaders entered Europe at the hands of the fur business and have an environmental impact, since they compete with native species to survive, and economically, due to the damage they cause, for example, in agriculture.
“Work with the American mink is essential if we want to maintain European mink populations because one preys on the other and competes for the same space.” To capture them they will use floating platforms, a system that has proven to be very effective and developed in the United Kingdom.