Genetic variation in restored Atlantic salmon (Salmo salar L.) populations in the Ulla and Lérez rivers, Galicia, Spain

Abstract The populations of Atlantic salmon in the Ulla and Lérez rivers, located in Galicia in northwestern Spain, were close to extinction early in the 1990s. A restoration programme involving supportive breeding has been conducted since 1995, using a mixture of salmon populations from several Galician rivers. The programme utilizes progeny of adults returning to the rivers and wild parr reared in fresh water until maturity. Five microsatellite loci were used to compare genetic variability in the restored populations with that in populations before their collapse in the 1950s. DNA samples were obtained from scale collections (old samples) and from tissue samples of live fish caught in the rivers (modern samples). Average heterozygosities and allelic richness are very similar in modern and old samples. Populations inhabiting the Ulla and Lérez rivers today are more similar than they were in the past, possibly because they originated in the same stock mixture.