Ecological fragmentation of rivers, and therefore of habitats, is a key problem affecting rivers of the Bay of Biscay which flow through basins shared by 3 regions and 2 countries: Navarre and Gipuzkoa (Spain) and the Atlantic Pyrenees (Nouvelle Aquitaine, France). This fragmentation has negative effects on the conservation of some species in the area: species that are priority conservation targets in the management plans of 15 Natura 2000 sites in the Bay of Biscay. Various historical and geographical factors mean that rivers in this area have a large number of obstacles interrupting their continuity. These rivers also have short courses (in the order of tens of kilometres) so there is a high density of impassable obstacles, with more than 1 per kilometre of river. As a result, ecosystems and habitats are altered and the ranges of the most sensitive species (semi-aquatic mammals and fish) are reduced or fragmented. This, coupled with genetic isolation and other associated effects, jeopardises their conservation and ability to recover or cope with additional pressures, severely reducing their resilience.
LIFE KANTAURIBAI’s goal is to improve the conservation status of key species and habitats of rivers flowing into the Bay of Biscay. It aims to do so by restoring the ecological connectivity of rivers in the Oria, Urumea, Bidasoa, La Nive and La Nivelle basins. The species and habitats targeted include salmon, lamprey, shad, eel, Margaritifera (a genus of freshwater mussels), Pyrenean desman, European mink and some alluvial forests.
The project’s specific objectives are to:
- Eliminate or make passable 30 obstacles;
- Reduce the main threats to diadromous fish (which migrate between freshwater and saltwater) in the project area: major river discontinuity and the impact of some hydroelectric power plant turbines on downstream migration;
- Install an automated control and monitoring system for migratory fish species, allowing them to be monitored with minimal human intervention;
- Improve the conservation status of Margaritifera, Pyrenean desman, otters and European mink in the rivers covered by the project through a programme of population reinforcement, translocations and actions to reduce the main threats to the last nuclei of desman and mink;
- Restore alluvial forests in places where they have been replaced by introduced species of flora (false acacia, American oak and Pennsylvania ash);
- Control and/or eradicate invasive alien species (American mink, coypu, muskrat and flora) present in the rivers covered by the project and which directly affect conservation of the target species and habitats; and
- Create an organisation that allows international coordination for the management and monitoring of migratory fish species between the 3 regions through which the Bidasoa basin’s rivers flow.