Morphological Features and Endoparasite Fauna of Some Whitefishes and Grayling Fishes from the Eastern Part of Lake Sobachye (the Putorana Plateau)

The present study addresses the morphological features of cisco, round whitefish and grayling. These fish species are the most abundant representatives of Coregonidae and Thymallidae in the eastern part of Lake Sobachye. The local cisco (Coregonus sp.) is closer to vendace (Coregonus albula) than to least cisco (Coregonus sardinella) in its diagnostic features. Ciscoes with a low number of vertebrae (the average number significantly below 60) were previously found in the Khantayka River and Khatanga River basins. C. sardinella is a cisco with a high number of vertebrae (more than 60 on average), which inhabits all basins, along with cisco populations that have a low number of vertebrae. Analysis of mitochondrial DNA polymorphism (mtDNA) of the cisco (Coregonus sp.) from Lake Sobachye showed a significant similarity between this population and the cisco from European water bodies (C. albula). The basic meristic traits of the round whitefish (Prosopium cylindraceum) from Lake Sobachye and other lakes of the Putorana Plateau are considered in the present study. The round whitefish in the water bodies of the Norilo-Pyasinskaya system is represented by a single population. All known groups of the Taymyr round whitefish are rightfully considered as typical representatives of the “Arctic” group. Thus, there is no reason to distinguish between the “Arctic” and “Boreal” groups. The round whitefish in the water bodies of the Norilo-Pyasinskaya system is represented by river and lake-river forms. For the first time, complete morphological characterization of the Siberian grayling (Thymallus arcticus) has been given for this region. Research of parasite fauna of cisco, round whitefish, Siberian grayling and whitefish (Coregonus lavaretus) showed that Lake Sobachye is a site of diphyllobothriasis. The cestode Diphyllobothrium dendriticum carriers are whitefish (C. lavaretus) and cisco (Coregonus sp.). Compared with the results of previous studies, the rate of fish infestation with parasites associated with the zooplanktonic organisms has increased: the prevalence of cisco by D. dendriticum has increased from 73% (2002-2004) to 96%, and the average intensity of parasitic infestation has increased from 4 to 8 individuals