Mitochondrial DNA variation in sea trout from coastal rivers in the southern Baltic region

Abstract

Sea trout ( Salmo trutta m. trutta ) populations are intensely stocked in Poland. It is estimated that over 90% of smolts migrating from rivers to the sea are offspring of locally caught spawners, artificially bred for over one year. Mitochondrial DNA variation in the populations of sea trout from six Polish rivers was investigated by RFLP analysis of PCR-amplified NADH-dehydrogenase 1 and 5/6 segments of mtDNA. Sixteen composite haplotypes were identified. Limited variation in the frequency of haplotypes between populations (χ ² = 116.46, p<0.001) was observed. Only the Słupia River population differed from the other five. Close similarity between Vistula River and the Pomeranian Rega and Parseţa rivers in a neighbour-joining tree indicates the presence of Pomeranian trout in the Vistula River system. In order to explain the possible causes of low differentiation of mtDNA among these sea trout populations, a comparison has been made to that found among populations from geographically close rivers in Bornholm Island, Denmark based on the literature data.

Author notes

present address: Polish Secretariat for the Helsinki Convention, Kossaka 1, 80-249 Gdansk, Poland, fax: [phone]; e-mail: