Phylogeographic lineages and differentiation pattern of Atlantic salmon (Salmo salar) in the Baltic Sea with management implications

Abstract

The genetic structure and isolation pattern of the Atlantic salmon (Salmo salar) throughout its range in the Baltic Sea were examined as a starting point for a conservation strategy for the species in this area. The allozyme variation in seven polymorphic loci was studied in 5125 salmon from 24 rivers in four countries. A clear dichotomy was observed between stock groups from southeastern (Russia, Estonia, Latvia, southern Sweden) and northwestern (northern Finland, northern Sweden) drainage regions, corresponding to the postglacial colonisation of the Baltic Sea by two phylogeographic lineages, one from the east (the Ice Lake lineage) and one from the west (the Atlantic lineage). The geographical and genetic distances between stocks fit the one-dimensional "isolation-by-distance" model (p < 0.001). The estimated gene flow ranged from 0 to10 migrants per generation. The total diversity of hatchery stocks was 72% of that of the wild stocks. Genetically similar stock groups, phylogeographic lineages, and drainage regions are recommended for use as genetic management units in addition to stock level.

Restricted matrilineal gene flow and regional differentiation among Atlantic salmon (Salmo salar L.) populations within the Bay of Fundy, eastern Canada

“…However, the observation that variation among regions is greater than within regions is surprising as significant regional differentiation has only previously been reported on larger geographical scales. The division of European stocks into Baltic and non-Baltic groups (Koljonen et al, 1999;Nilsson et al, 2001) involves a spatial scale where the Baltic Sea alone, at 422 000 km 2 , is over 20-fold larger than the Bay of Fundy. The regional differentiation observed is predominantly attributed to the difference between populations from the geographically distinct Minas Basin rivers and those elsewhere in the Bay of Fundy.…”

“…The absence of a phylogenetic distinction between the two life-history forms is supported by allozyme studies in both Europe and North America (Ståhl 1987;Verspoor, 1994) though anadromous and non-anadromous populations have diverged sufficiently in some cases to exist sympatrically (Verspoor and Cole, 1989). However, molecular studies do show a deep phylogenetic division between North American and European salmon stocks (Ståhl 1987;Verspoor, 1997;King et al, 2000), and a shallower division of European stocks into Baltic and Atlantic (ie, non-Baltic) groups (Ståhl, 1987;Koljonen et al, 1999;Verspoor et al, 1999;Nilsson et al, 2001). In North America, regional differences have been detected in relation to transferrin variation (Verspoor, 1986) but the evolutionary basis of these regional differences is unclear and detailed phylogeographic studies of North American populations are lacking.…”

Analysis of gene associated tandem repeat markers in Atlantic salmon (Salmo salar L.) populations: implications for restoration and conservation in the Baltic Sea

“…They represent two distinct population groups within the Balticthe Gulf of Bothnia and Gulf of Finland, which likely originate from distinct glacial refugia (Koljonen et al 1999;Nilsson et al 2001). In the Gulf of Bothnia, the hatchery stock of R. Umea¨lven was founded during the 1950s based on wild fish from its tributary R. Vindela¨lven.…”

Haplotype Frequency Distribution in Northeastern European Saduria entomon (Crustacea: Isopoda) Populations. A Phylogeographic Approach

“…The passage of the fauna into the Baltic region would have been possible through the ice-margin basins which were apparently located along the southeastern edge of the retreating ice sheet, before or during the Baltic Ice Lake stage, ca. 13 000-10 500 BP (SEGERSTRÅLE, 1982;KOLJONEN et al, 1999;KOSKINEN et al, 2000). At the Yoldia Sea stage, 10 300 -9 000 BP (DONNER, 1995) the connection between the Baltic basin and the Ice Lake of the River Onega area was closed as a result of the uplifting of the landmass of contemporary Finland and southern Sweden and proglacial lakes system draining.…”