Genetic assignment of marine-caught adult salmon at Armadale to region of origin

Scottish Marine and Freshwater Science Vol 6 No 16

Historical tagging studies have shown that there was considerable scatter in the recaptures of salmon tagged in various locations around Scotland, with fish being found far from their natal rivers. More recently, satellite tags have enabled at-sea locations of salmon on their return migrations to be collected in Scottish waters. However, a thorough understanding of the tagging information was constrained by a lack of knowledge of where the salmon were headed before their tags detached. Here, genetic assignment techniques are used in order to investigate the origins of salmon satellite-tagged at Armadale on the north coast of Scotland. The marine distribution of tagged fish assigned to different parts of Scotland showed no obvious pattern. As such, results of this analysis confirm those seen with conventional tagging investigations and show that homing fish show considerable spatial mixing around the Scottish coast before finally returning to their natal rivers. It is thus also clear that the deployment of renewable energy devices may not only affect local salmon populations, but also more distant ones.