Research Article

Conservation Genetics

, Volume 15, Issue 5, pp 1095-1109

First online:

Origins and genetic diversity among Atlantic salmon recolonizing upstream areas of a large South European river following restoration of connectivity and stocking

  • Charles PerrierAffiliated withDépartement de Biologie, Université LavalUMR 0985 ESE, INRA Email author 
  • , Jérôme Le GentilAffiliated withUMR 0985 ESE, INRAUMR 1224 Ecobiop, INRA
  • , Virginie RavigneAffiliated withUMR BGPI, CIRAD
  • , Philippe GaudinAffiliated withUMR 1224 Ecobiop, INRA
  • , Jean-Claude SalvadoAffiliated withUMR 1224 Ecobiop, INRAUMR 1224 Ecobiop, Université de Pau Et des Pays de l’Adour

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The restoration and maintenance of habitat connectivity are major challenges in conservation biology. These aims are especially critical for migratory species using corridors that can be obstructed by anthropogenic barriers. Here, we explored the origins and genetic diversity of Atlantic salmon (Salmo salar) recolonizing upstream areas of the largest South European Atlantic salmon population (Adour drainage, France) following restoration of connectivity and stocking. We genotyped 1,009 juvenile individuals, sampled either in continuously inhabited downstream sites or in recently reconnected and recolonized upstream locations, at 12 microsatellite loci. We found significant fine scale genetic structure, with three main genetic clusters corresponding to the Nive, Nivelle and Gaves rivers. Within each of these clusters, samples collected in continuously inhabited and recently recolonized sites had comparable allelic richness and effective population sizes and were only weakly differentiated. Genetic structure among basins was also similar among continuously inhabited and recently recolonized sites. The majority of the individuals sampled from recently recolonized sites were assigned to neighboring continuously inhabited downstream sites, but noticeable proportions of fish were assigned to samples collected in more distant sites or identified as putative hybrids. Overall, this study suggests that the restoration of accessibility to upstream areas can allow for the recolonization and effective reproduction of Atlantic salmon from proximate downstream refugia, which does not decrease local diversity or disrupt existing genetic structure.


Recolonization Genetic diversity Dam Connectivity Assignment Salmo salar