Efficiency of artificial reproduction of the Posolsk subpopulation of Baikal omuls (Coregonus migratorius)
For 85 years Bolsherechye Fish Factory has reproduced Baikal omuls (Coregonus migratorius). In total, 35.8 billion larvae were produced in Lake Baikal. The information available makes it possible to analyze performance of the factory. During the first forty tears annual volumes of larvae the factory produced were growing steadily. From the beginning of 1970s till 2007 the number of produced larvae remained within the range from 0.43 to 0.93; or 0.67 billion larvae in average. Later, the volume ofproduction started decreasing to 49.5 million larvae it reached in 2016 due to shortage of spawners. On the whole, during the first 40 years of operation the number of spawning fish stock of the reproduced population grew from 30-50 thousand species to 962 thousand species. From 1972 till 1990 catches of spawning omuls were steadily dropping to 69 thousand species. This drop was attributable to response of the population to flow control in Baikal. Later, the annual number of fish entering Baikal was growing again having increased up to 0.5 million species by 2004. This growth was attributable to adaptation of omuls to the new environmental conditions. At the present moment the population reproduced by the factory is decreasing. The number offishes caught annually fluctuates within the range from 9.3 to 20.5 thousand species. The share of spawners returning to spawning grounds in the total number of larvae produced in the generation for the years of operation varied from 0.001% at the present moment to 1.601% in 1946, with an average share of 0.125%. We detected inverse relation between the annual number of produced larvae and the rate of spawners return to spawning grounds, which is attributable to trophic level limits of Posolsk Sor which plays the role of a nursery pond. Increase in the volume of larvae production to more than 400 million a year had a negative impact on the number of spawners returning to spawning grounds. Analysis of performance of the factory demonstrates fundamental opportunities to reach great abundance of the reproduced populations through mass omul larvae production without nursing. The present low efficiency of industrial reproduction of omuls is related to combined negative effects of ecological, social, and economic factors.