Genetic Characteristics of Brook Trout Salvelinus fontinalis (Mitchill, 1848) Broodstocks from Hatcheries in Bosnia and Herzegovina

The most commonly farmed fish species in Bosnia and Herzegovina’s aquaculture are from the family Salmonidae, including brook trout Salvelinus fontinalis which is reared both for consumption and stocking purposes. A number of farmers complained about the elevated frequency of anatomical deformities in the smolts and fingerlings of brook trout, decreasing their fitness rate and causing significant financial loss. Since it has been shown that occurrence of deformities is correlated with the low genetic diversity and high inbreeding, this study aimed to assess intra- and interpopulation diversity of Salvelinus fontinalis from different freshwater fish farms in Bosnia and Herzegovina by observing variation in mitochondrial and nuclear genome. Total of 109 samples of brook trout from three hatcheries located at the Neretva River were analyzed for the mitochondrial control region and seven nuclear microsatellite loci. Both PCR-RFLP and sequencing revealed only one haplotype of the control region in all investigated trout. Overall, a low number of genotypes was evident across all the observed loci. Values of genetic diversity and polymorphic information content followed the increase in the number of alleles per locus. In general, values of inbreeding coefficient were generally very high, while the genetic diversity and observed heterozygosity had low rates. The results of our study are congruent with the findings of previous studies in which developmental deformities were concomitant with the low genetic diversity and inbreeding depression. It is, therefore, strongly advised to regularly supplement the broodstock with new, unrelated individuals, as it is of vital importance for sustaining a satisfying level of genetic diversity and preventing inbreeding depression. Additionally, maintaining good management practices regarding the fluctuation of water temperature, exposure to pollution, nutrition, etc., will further contribute to the prevention of this detrimental condition.