Three salmon broodstocks : Rutki (RUT) , Aquamar (AQU) , Żelkówko (ZEL) and its two river populations: Słupia (SLU) and Parsęta (PAR) were investigated. Eleven microsatellite loci were amplified and genotyped . The values of the genetic variation indicators were calculated.
Among the stocks the total number of alleles detected across all loci ranged 46-81 (Table 1) . The average observed heterozygosity across all stocks (AC) and loci was 0.59; expected heterozygosity was 0.58 . The populations remained in Hardy-Weinberg equilibrium. The average value of Garza-Williamson M index for all populations was low. The inbreeding values per generation ranged from minus 0.08% to 0.08%. Genetic distance was high between the Lithuanian stock (RUT and PAR ) and that of Latvian origin (AQU , ZEL and SLU) (Table 2). Several admixture traces were recorded in all stocks with the smallest evidence in RUT (Figure 1).
The genetic diversity in the investigated stocks/populations is slightly lower than that usually recorded in the Baltic Sea salmon populations , probably due to genetic isolation, founder/bottleneck effect, and genetic drift. The actual level of inbred or outbred in the Polish salmon is not high enough to be a problem in the production of its stocking material. However, monitoring of inbreeding and other indicators of salmon genetic variation would be recommended.