TEMPORAL VARIATIONS OF GENETIC INTROGRESSION IN STOCKED BROWN TROUT POPULATIONS

Allozymes were used to analyse the genetic impact of hatchery brown tr out Salmo trutta, morpha fario stocked in wild Mediterranean populatio ns to gain a better understanding of the mechanisms of introgression ( regulation, elimination or homogenization). Analysis of the genetic st ructure of populations from the same river drainage basin but subjecte d to different incidences was performed in space and time (data on two generations and 2 years of sampling). Introgression is associated wit h high deficits of heterozygotes and linkage disequilibria. Genetic di vergence according to age group was observed. These results may indica te selective forces acting against domesticated genes and limiting hyb ridization between the two forms. (C) 1998 The Fisheries Society of th e British Isles.