The use of molecular markers for the characterisation and rehabilitation of indigenous trout populations in the Central Alpine region

The brown trout (Salmo trutta L.) represents one of the most differentiated vertebrate species. However, human activities such as habitat alteration, overexploitation and introgression of non­ native hatchery fish led to an alarming reduction of population variability. This is particularly evident for vast parts of the highly fragmented alpine area. Because of these facts the Interrreg IIIA-project "Trout-Examinvest" was initiated in order to achieve the following goals: ♦ Genetic characterisation of local trout populations ♦ Identification of potential autochthonous populations ♦ Establishm ent o f indigenous hatchery strains for Conservation management In the framework of our project two molecular techniques were applied: (i) sequence analysis of the complete mitochondrial DNA control region and (ii) analyses of a number of variable microsatellite DNA loci. As was shown in previous studies, mitochondrial DNA revealed to be a useful tool in the screening of frequencies and distribution patterns ofthe major trout lineages. On the other hand, microsatellite DNA data delivered more detailed information about withinpopulation genetic diversity and population structure as well as about hybridisation between native and introduced trout lineages. Based on these findings we point to the necessity of using a combined approach of molecular analyses to select and establish indigenous trout breeding strains for future stocking and repopulation measures.