Size and Age Structure and Demographic Characteristics of Coregonus sardinella Valenciennes, 1848 of the Khatanga River Basin

Coregonus sardinella Valenciennes in the Khatanga River basin (Taymyr Peninsula) had always been considered a component of ichthyocenosis and has never been the subject of special studies. As well-known published materials show, Coregonus sardinella in the Khatanga River basin are represented by semianadromous, lacustrine, and lacustrine–riverine forms. In this work, the features of the size and age structure characteristics, fecundity, migration, and fishing in modern conditions of the semianadromous form of Coregonus sardinella are analyzed. During the study period (2010–2018), fish with a length of 186 to 364 mm and a weight of 54 to 442 g were detected in the spawning stock of semianadromous Coregonus sardinella in the Khatanga River basin: an average of 275 mm in length and 163 g in weight at the age of 5+ to 15+ years. Males slightly prevailed over females in number (57.3 and 42.7% respectively). The individual absolute fecundity (IAF) has been shown to vary from 4600 to 36 700 eggs, on average 13 400, during the period 2010–2018. Individual relative fecundity (IRF) varied from 37.5 to 172 pcs/g of body weight, on average 88.4 pcs/g. The boundaries of the main spawning grounds were specified, which are located in the section of the Kheta River from its mouth to the mouth of the Boganida River (a tributary of the Kheta River, 414 km from the mouth) and the Khatanga River, 20 km from the confluence of the Kheta and Kotuy rivers.