Evidence of temporal genetic change in wild Atlantic salmon, Salmo salar L., populations affected by farm escapees

A large number of farmed Atlantic salmon escape from sea cages and hatcheries annually. Selection programmes and domestication have changed the genetic composition of farmed salmon to improve their performance in the culture environment, which apparently occurs at the cost of their fitness in the natural environment. Therefore, gene flow from fanned salmon to wild salmon populations may have altered the genetic composition of wild salmon populations. To investigate the temporal genetic stability in seven wild Norwegian salmon populations, genetic profiles were produced from historical and contemporary scale samples. Historical and contemporary samples of salmon from the Namsen, Erne, Opo, Vosso, Granvin, Eio, and Hi Rivers were genotyped at the following eight microsatellite loci: Ssal3.37, Ssa28, SsOSL85, Ssa197, Ssa20.19, SsaF43, Ssa202, and Ssa85. A significant change in genetic profiles was observed over time in the Opo, Vosso, and Eio Rivers, but no changes in genetic profiles were observed in the Namsen, Etne, Granvin, and Hi Rivers. A small reduction in FST values and genetic distances among populations was observed in the contemporary samples compared with the historical samples, indicating a eduction in population differentiation over time. (c) 2006 International Council for the Exploration ofthe Sea. Published by Elsevier Ltd. All rights reserved.