Idengification of the origin of an Atlantic salmon (Salmo salar L.) population in a recently recolonized river in the Baltic Sea

Abstract

The founder event in a recently recolonized salmon population in the Baltic Sea (Gulf of Finland) was investigated. To identify the origin of the founders, four wild populations and two hatchery stocks were analysed using six microsatellite loci. The results of assignment tests and factorial correspondence analysis suggest that the initial recolonizers of the river Selja originated from the geographically nearest (7 km) wild population (river Kunda) but as the result of stocking activities, interbreeding between recolonizers and hatchery individuals has occurred in subsequent years. Although the hatchery releases are outnumbering the wild salmon recruitment in the Baltic Sea at present, our results suggest that the native populations may still have an important role in colonization processes of the former salmon rivers.

Can the lost migratory Salmo trutta stocks be compensated with resident trout stocks in coastal rivers?

“…The new trout stock then had a mixed origin from two or more genetically distinct donor anadromous stocks (Knutsen et al, 2001). A similar phenomenon has also been observed in an Estonian river after the extirpation of the original stock of Atlantic salmon (Vasemägi et al, 2001).…”

“…As trout have a large behavioural plasticity (Walker, 2006), it is possible that migratory trout could evolve from resident trout or vice versa. At least new sea trout and Atlantic salmon stocks have arisen as a consequence of recolonization (Knutsen et al, 2001;Vasemägi et al, 2001). The growth rate of trout is known to largely depend on environmental conditions, as shown in a transplantation experiment with resident and anadromous fish (Jonsson et al, 1995).…”

Stocking may increase mitochondrial DNA diversity but fails to halt the decline of endangered Atlantic salmon populations

“…Historic collections (especially of fish scales) are particularly useful for the investigation of longterm genetic processes and perturbations to genetic structure. Several previous studies have been able to use such historic collections to examine long-term temporal trends of populations structure (Nielsen et al 1997) and questions such as immigration of hatchery released fish into wild populations with the effect of genetic homogenization (Vasemagi et al 2001).…”

A set of 37 microsatellite DNA markers for genetic diversity and structure analysis of Atlantic salmon Salmo salar populations

“…First, 73 S. salar microsatellite markers were selected for high levels of polymorphism, diploidy, spacing across genome (unpubl. data) and their use in the scientific literature or projects from c. 850 markers in the database (King et al, 2001;Landry & Bernatchez, 2001;Vasem¨agi et al, 2001;Tiira et al, 2003;Withler et al, 2005). These 73 markers were tested on 367 wild adult anadromous S. salar from four European rivers (L'Oir and Scorff in France, Shin and Spey in Scotland), and 37 markers were selected for their high quality of amplification, easy peak identification and high level of genetic variability.…”