Hematological parameters of blood in a sedentary population of Arctic char Salvenius alpinus L. (Salmoniformes) with parasitocenoses

This work presents the results of the study of mature individuals of Arctic char (Salvelinus alpinus L.) from Lake Ulu located in the Oymyakon district of the Republic of Sakha (Yakutia). The study was conducted as a result of control catching; fifty-two individuals of Arctic char were caught. The following parameters were measured for each fish: standard length (SL), body weight, fish age by scales and otoliths. The maturity state of the gonads and intestinal contents were also assessed. Microscopic parasites were counted by microscopic examination of a series of compression preparations of biomaterial in transmitted light using a Bressr LSd5-005 microscope (Bresser Ltd, China). The number of macroscopic parasites of each species found in each individual was recorded. Measurement of size and weight parameters and ichthyopathological examination of the char revealed a significant parasitic load that negatively affects the growth rate and the state of the population of this fish species. Less than half (42.8%) of the examined fish were free of parasites. The parasitocenosis was represented by two nematode species (Cystidicola farionis, Raphidascaris acus), a cestode (Proteocephalus thymalli) and an acanthocephalan (Neoechinorhynchus salmonis). The highest number of parasites was found in the gastrointestinal tract of the examined fish. Hematological parameters of the blood of fish without invasion and invaded individuals demonstrated reliable (p <0.05) differences in the occurrence of lymphocytes (decrease in invaded individuals), neutrophils (increase to 16.9±2.0% in invaded) and basophils (increase to 1.9% in invaded). The obtained results of diagnostics and parasitological state of the char population, characterized by low growth rate and low occurrence of older age groups, indicate the possibility of increasing fish productivity of the reservoir by suppressing parasite fauna.