North of the Loire-Atlantique, Lake Vioreau is being emptied before major restoration work on its dam.
For the past few days, volunteer fishermen have been taking turns to capture and then transfer the many fish from this reservoir to other bodies of water in the area.
“There are people in there!
Immersed in cold water up to their chests, the small group of fishermen gradually bring their huge net to the shore.
Thanks to this traditional technique called “seine fishing”, more than a hundred kilos of fish were caught in one catch on Wednesday afternoon.
Among them, a lot of catfish, bream, but also impressive pike-perch with a length of at least 70 cm.
A small panel of what is usually found in Lake Vioreau (Loire-Atlantique), north of Nantes, a gigantic hydraulic reservoir of 180 hectares, which will be completely emptied by Christmas.
For a year, the site, like the Nantes-Brest canal that it supplies, will therefore be dry.
But before this exceptional emptying, hired by the department to carry out restoration work on the 19th century dam (at a cost of 16.7 million euros,
), a backup fishery must be carried out.
An operation intended to move the hundreds of thousands of carp, roach or pike that inhabit this "mecca of fishing in the Loire-Atlantique".
“For a month, our volunteers will carry out one or two catches a week in the quarry, where the water and the fish arrive downstream of the dam, explains Bernard Hamon, president of the Loire-Atlantique fishing federation.
We will then intervene in the lake when the level is very low, between 1m20 and 1m60, with increasingly fine meshes.
Transferred to nearby bodies of water
On the large “sorting table” mounted on trestles, the fish move about in all directions before being dispatched, by hand, into basins.
It takes at least two people to then load them into the trucks, equipped with oxygen bottles, which will transport them to different bodies of water in the surroundings, their new vacation spots.
“We must not drag on, to avoid them generating too much stress, observes Vincent Mouren, director of the fishing federation.
Especially since these fish, like carp, appreciate large bodies of water.
» The very numerous catfish or crayfish, considered as invasive species, will be eliminated.
In total, between 30 and 40 tons of fish could be taken out of the water.
All these beautiful people should return to Lake Vioreau in the winter of 2023-2024, when the restored site will have been filled with water naturally, by the rain.
“It's a bit sad for the fishermen [recreational fishing is obviously prohibited throughout this period] because Vioreau was reaching its full potential, confides Bernard Hamon, who is however trying to see the positive points of this imposed break.
A real inventory of species will thus be established.
“Natural habitats” will also be created for the fish, so that they feel even better there than before.
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The main stages of the construction
After fishing and draining, the work will get to the heart of the matter with the construction of the intake tower, which will centralize the hydraulic management elements.
The wall will be sealed, then part of the cleaning of the reservoir will begin.
To stabilize the dam, buttresses will finally be added, before a gradual refilling of the water, from the end of 2023. During the works, it is forbidden to circulate on the body of water and the banks.
Pays de la Loire
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