REPRODUCTION AND GENETIC DIFFERENTIATION OF NELMA (STENODUS NELMA PALLAS, 1773) IN LARGE RIVER BASINS OF WESTERN SIBERIA

The assessment results of natural reproduction and population structure of nelma in the Ob and Taz basins are presented. Based on the number of the larvae that migrated from spawning grounds and the dynamics of catch, a conclusion about a constant decrease in the species population over 60 years was made. Long-term analysis of the size-age variability of nelma in the Severnaya Sos'va River indicated a stable rejuvenation of the spawning stock at the present and the absence of re-matured individuals. An analysis of the genetic differentiation of the nelma populations of the Ob and Taz was performed. The lack of the differences between two basins indicated the genetic proximity of the nelma populations within Western Siberia. The possibility of restoring the nelma population through artificial reproduction was assessed.