Effects of stocking on the genetic structure of brown trout, Salmo trutta, in Central Europe inferred from mitochondrial and nuclear DNA markers

Abstract

Stocking has had a considerable effect on wild brown trout, Salmo trutta L., populations throughout Europe. To elucidate this impact and to outline further management strategies, the genetic structure of 25 wild populations and five hatchery stocks from Czech Republic and Slovakia were analysed using mitochondrial (control region) and nuclear DNA (microsatellites, LDH‐C1*) markers. Stocking practices have caused massive hybridisation between the Atlantic and Danube brown trout strains in the central Danube basin and have lead to a loss of among‐population divergence in Slovakia and the eastern part of Czech Republic. Comparison with studies from neighbouring countries revealed substantial differences in haplotype, allele frequencies and genetic diversity across Central Europe. Differences in stocking management and origin of breeding stocks appear to be crucial factors for the spatial variability of the genetic structure of brown trout.

Genetic diversity and phylogenetic origin of brown trout Salmo trutta populations in eastern Balkans

“…In the second analysis, two hatchery populations of different Atlantic origin (IT, LO) and three wild populations (ZP, JP, OD) from the North and Baltic Sea basins in the Czech Rep. was included. These populations were found to be of pure Atlantic origin in the previous study (Kohout et al 2012). Populations with extremely low sample size (?…”

“…Sequencing of mtDNA control region provided readable sequences of 994 bp corresponding to the segment analysed in the previous studies from Central Europe (Duftner et al 2003;Kohout et al 2012). Among 204 individuals originating from 16 sampling sites, a total of 23 haplotypes was revealed, 15 of which were found for the first time (Tables 1 and 2).…”

“…land (Meraner et al 2007), Czech Republic and Slovakia (Kohout et al 2012). All haplotypes found in the Caspian Sea basin and two inland lake basins in Iran (Vera et al 2011;Segherloo et al 2012) and the Aral Sea basin (Griffiths et al 2009) belonged also to this group.…”

“…The hybridisation of local populations with non-indigenous brown trout, mostly of Atlantic origin has been widely observed (e.g., García-Marín et al 1998;Hansen 2002;Sanz et al 2006;Thaulow et al 2013). Extensive hybridization between the Atlantic and Danubian mtDNA lineages due to the repeated transfers and long-term stocking have been reported in the upper/middle Danube River basin (Weiss et al 2001;Duftner et al 2003;Kohout et al 2012). Stocking activities and their impacts on genetic structure has been reported also in eastern Balkans.…”

“…The extensive impact of stocking has been reported in central European parts of the North, Black and Baltic Sea basins, where the genetic variability among populations is almost lost (Kohout et al 2012).…”