FAUNA OF PARASITES OF SALMON FISHES (SALMONIDAE, PISCES) OF THE ONEGA AND LADOGA

It is studied the fauna of parasites of fresh-water forms of a salmon (Salmo salar L.) and trout (S. trutta L. ) of the Onega and Ladoga. It is defined its similarity. One of the main distinctive signs the fauna of parasites of the Ladoga fishes is reduced to infection of them by proboscis worms of genus Corynosoma. Being sea relicts, they serve as the evidence of former relations of the Ladoga with the Baltic Sea. Such types as monogeneses Gyrodactylus salaris are presented in the Onega. Being ice relicts, they remain only in those reservoirs, which underwent insignificant changes in the Holocene and are closer than others are to primary oligotroph (ultraoligotroph) lakes. The formation of G salaris happened in the periglacial lakes and was connected with existence in them of fresh-water populations of the Atlantic salmon. Thereof this specie did not manage to extend beyond the Baltic Sea.