Research topics

1) Genetic structure and changes at DNA-level

The genetic structure and phylogeographic history of Atlantic salmon in the Baltic Sea range have been analysed (Koljonen et al. 1999, Säisä et al. 2005 ). The molecular genetic effects of hatchery rearing are assessed in Koljonen et al. (2002), and the effects of historical changes over several decades since building of Atlantic salmon dams and several generations hatchery breeding are evaluated in Säisä et al. (2003). The management implications of genetic structuring for Baltic salmon are summarized in Koljonen 2001.

2) Stock identification:

Stock identification research started with allozyme analysis (Koljonen 1995). Currently a 17-loci DNA-microsatellite database covering more than 30 Baltic Sea salmon rivers is available as baseline data and three catch samples are analysed annually (Baltic Main Basin, Åland Sea, Bothnian Bay). Proportion estimates covering the first five-year monitoring period were published in 2006 (Koljonen 2006). Estimation methods have been discussed in Koljonen et al. 2005 and Koljonen et al. 2007.

3) Quantitative traits, life-history characteristics

It is important to know how artificial selection in a hatchery environment affects the genetic traits of salmon stocks and whether it can change the inherited life-history traits. The research has shown that the progeny of ranched parents grew faster in the sea and matured after a single sea-winter more often than the progeny of wild parents (Kallio-Nyberg and Koljonen 1997). These results support the hypothesis that selective factors have a different effect in a hatchery than in the wild.

Stock-specific variation and inheritance of the sea migration pattern among Atlantic salmon were examined in transplantation and crossing experiments (Kallio-Nyberg and Ikonen 1992, Kallio-Nyberg et al. 2000). The results show that salmon stocks have a genetically determined tendency to follow a stock-specific sea migration pattern independent of the release site. The sea migration of the stock hybrids differed from that of the pure parental stocks released in the same place at the same time (Kallio-Nyberg et a. 2000). The hatchery-reared salmon also followed a shorter feeding migration route than the wild fish (Jutila et al. 2003).

The effect of genetic origin and environmental factors on the feeding migration was studied by analysing tag recovery data with logit-models (Kallio-Nyberg et al 1999). All the variables – genetic stock, smolt length, release year and herring abundance – had a significant effect on the migration pattern Genetic, stock-specific differences were observed in the sea migration pattern. The results show that the feeding migration pattern is both genetically and environmentally controlled.

The effect of hatchery-rearing and environmental conditions on marine survival was studied by analysing tagged and released smolts (Saloniemi et al. 2004). On average, wild smolts had a 4.5 times higher survival rate than reared fish of the same smolt size. The difference in the observed tag recovery rates as such was only about twofold, as the larger size of the reared compared with the wild smolts compensated for their lower survival rate. The better survival of the wild smolts was more pronounced in the low-survival year than in the high-survival year.

The effect of environmental factors and smolt length on marine survival was studied in a wild and reared stock with the same genetic origin (Kallio-Nyberg et al. 2004). The recapture rate among wild Atlantic salmon groups showed no decreasing or increasing trend between 1980 and1993. Among reared salmon groups, the recapture rate followed a decreasing trend in 1986-1988.

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