Features of parasitic diseases of salmonid fish in fishery reservoirs of the Leningrad region and Karelia

Abstract

The probability of occurrence of parasitic diseases of salmonid fishes in modern fish-breeding enterprises of the Leningrad region and Karelia is very significant. Wild fish, in particular whitefish, are a reservoir of invasion, intermediate and final hosts for a number of parasites that are dangerous for rainbow trout. The purpose of this work is to study the characteristics of parasitic diseases of salmonids in fishery reservoirs of the Leningrad Region and Karelia. The studies of the parasite fauna of vendace were carried out in the period from 2019 to 2020. The examination of fish for the presence of parasites and their determination was carried out according to the generally accepted standard method. Of the helminthiases found in rainbow trout during artificial cultivation in the farms of the Leningrad Region and Karelia, monogeneans and cestodes present the greatest problem, and to a lesser extent, trematodes. In the fishery reservoirs of these regions, where cage aquaculture is actively developing, whitefish live, among which the European vendace or ripus (Coregonus albula) attracts special attention. In the study of the parasite fauna of vendace, 11 species of parasites from different systematic groups were noted. At the same time, gull tapeworm Diphyllobothrium dendriticum is of veterinary and medical importance. The parasites found in vendace can potentially be dangerous for cultivated salmonids, with special attention to the monogenetic fluke Discocotyle sagittata and the cestode D. dendriticum. These representatives of the ripus parasite fauna are also dangerous for rainbow trout. The control of the epizootic state makes it possible to detect infection and carry out a set of necessary therapeutic and preventive measures. Further study of the parasite fauna of wild whitefish in the lakes of the North-West of Russia is also important for the aquaculture of the region.