Scientific publications

Gyrodactylus parasites in grayling (Thymallus thymallus) and salmon (Salmo salar) were studied by molecular analysis of mitochondrial DNA in Russian Karelia. It was confirmed that grayling
parasites do not infect salmon, even if it is difficult to consider them as a different species. Grayling parasites are divided to White Sea basin and Baltic basin lineages, indicating separate glacial refugia for the host. Salmon stock in the river Keret is infected by Gyrodactylus salaris originating from the lake Onega, where the parasite is rare and causing no harm. In Keret, the salmon population
has no intrinsic or induced resistance, thus allowing the parasite to reproduce without restriction. The Pistojoki salmon population, spawning in Kuitozero, is infected by Gyrodactylus salaris of rainbow trout type, most probably originating from Finnish fish farms upstream. First observations
in 2001 indicated that the salmon stock of Pistojoki is parasite tolerant; further follow-up is needed to confirm this. The tolerance of certain salmon populations is correlated with the origin in freshwater glacial refugia, and long coexistence with Gyrodactylus.