@proceedings {8401,
	title = {Upstream as a sanctuary for the French populations of catalan chub Squalius laietanus (Teleostei , Leuciscidae) threatened by the allochtonous European chub S. cephalus},
	year = {2020},
	abstract = {In the Pyr{\'e}n{\'e}es-Orientales department (France), three Mediterranean catchments (Agly, T{\^e}t and Tech) are subject to high variations in water levels during Cevenol-type events. In order to fight against the effects of these floods, dams and wiers were built along these rivers with consequences on aquatic fauna, eliminating the ecological continuum. The chub Squalius is a potamodromous fish occurring from the salmonids stream to close to the estuaries. Moreover, whereas the European chub S. cephalus was thought to be represented by a single species in France, another species, endemic to Catalonia, was described: the Catalan chub S. laietanus. However, S. cephalus was also introduced in the catchments of this area with possibly threats of hybridization. Samples from eight populations of Squalius spp coming from these rivers were genetically identified using a DNA Barcoding approach with a mitochondrial (COI) and a nuclear (RAG1) markers. Our results confirm the presence of both species in the three drainages as well as their hybridization, threatening S. laietanus by hybridization as in 70\% of Mediterrannean endemic species. There is also a downstream-upstream gradient in the presence of S. cephalus in the T{\^e}t and Tech catchments. S. laietanus seems less impacted by S. cephalus in headwaters than downstream. One of the explanations would be the numerous weirs between these areas. If the negative impacts of the absence of ecological continuum on the ichthyofauna are known and cannot be denied, these weirs might form in this case a barrier against the presence of S. cephalus in headwaters. As a consequence, S. laietanus has been evaluated as EN in the last French UICN Red List published in 2019. While the ecological parameters still need to be examined, our study brings additional information for better suited conservation actions regarding the ecological continuum.},
	author = {Rose, Morgane and Dettai, Agn{\`e}s and Lef{\`e}bvre, St{\'e}phane and Blanc, Laurence and Poulet, Nicolas and Baudier, Olivier and Hautecoeur, M{\'e}lyne and Denys, Ga{\"e}l}
}
