Bottlenecks and genetic changes in Atlantic salmon (Salmo salar L.) stocks introduced in the Subantarctic Kerguelen Islands

Atlantic salmon stocks were planted in virgin streams of the Kerguelen Islands. The outcome of the introduction was different depending on the site and particularly on the stocking history. At the Korrigans system, where hatchery stocks were planted, salmon were replaced by brown trout (Salmo trutta) coming from neighbouring systems. A poor quality of founder stocks was reported as well as the presence of hybrids in the stock and low genetic variability. High interspecific hybridization rates were observed the first years of sympatric existence, then salmon disappeared from the system. However, at the Armor system, where wild Scottish stocks were planted, a population was established. The population is still present 25 years after the introduction. Loss of genetic variability indicates that both the Armor and the Korrigans population introductions suffered bottlenecks. The different outcomes of Atlantic salmon populations in the two systems are explained by the quality of the founder stocks and the interaction with brown trout. (C) 2004 Elsevier B.V. All rights reserved.