Abstract
Genetic variation at 24 enzymatic loci was investigated in eight south European Atlantic salmon populations from the rivers Nivelle, Cares, Sella, Narcea, Esva, Navia, Porcia and Eo. In these rivers, management based on supplementation of native populations with foreign stocks was carried out for more than one decade. Population genetic patterns expressed in terms of allele frequencies, mean heterozygosity and conformity to Hardy‐Weinberg equilibrium, were significantly different between populations. Relevant temporal changes of genetic variability were reported. Evidence that foreign stocking has disturbed the genetic patterns of some of the studied populations is presented.