Nivelle River is a 45km long cross-border coastal river. The first 12 km upstream flows into Spain. The next 33 km, including the river’s mouth into the Atlantic Ocean, are located in France. This river supports a variety of migratory fish, including two species of shad, sea lamprey, European eel, Atlantic salmon and sea trout. The number of salmon that swim up the river each year has fallen from an average of over 200 fishes in the period 1990-2000 to 100 fishes (in some years less than 50) in the last 20 years. This species is therefore in sharp decline and particularly threatened in this basin. The causes of the decline are multiple, as in other rivers (habitat quality, water quality, dams, professional fishing, etc.).
This river is also home to the last population of freshwater pearl mussels in the Pyrenees, which live in symbiosis with salmon and trout. It is also in great danger of extinction, and great efforts have been made in recent years to save this population. The upstream part of the river is also home to other rare and endangered species, such as the Pyrenean Desman (a small aquatic mammal endemic to the Pyrenees) and the White-clawed Crayfish. Currently, the upstream sector of the river has the best conservation status and spawning grounds for salmon and trout. Unfortunately, this section of the river is inaccessible due to the Urrutienea Dam.
Several fish-pass have been built on the two main dams in the downstream part of the Nivelle, but the Urrutienea Dam has never been equipped, despite the very high stakes for biodiversity. The owner has always been opposed to the construction of a fish-pass. For this reason, our association is currently in the process of buying the dam, with the aim of removing it when we become the owners. This project also has the support of the Government of Navarra in Spain, as it would allow the return of salmon to the Spanish section of the Nivelle. In the context of climate change, circulation of fish (and of all aquatic organisms in general) is becoming an increasing issue.
This project is very important locally, and it requires in-depth preliminary technical studies.
|Potential km to be opened||10|
|Key habitats||Spawning habitat for salmonids|
|Focal species||Salmon, brown trout, European eel, freshwater pearl mussel|
It is important to do topographic surveys, estimate the volume of sediment that will be remobilised and draw technical design documents. During this preparatory phase, the measures to limit the impacts during the works will also be defined. Finally, we have to draw up specifications and select the company that will present the best skills at the best cost. During this phase, we will also draw up the permission procedure.
FEDERATION DE PECHE 64
Basque Country Agglomeration Community
Government of Navarre