Эколого-морфологическая характеристика нерестового стада посольской популяции байкальского омуля Coregonus migratorius Georgi в современный период (по данным 2009–2020 гг.)

Abstract

The timing of the start and end of the spawning migration of the Baikal omul is specific for each of its populations, is closely related to the temperature regime in their areals and fluctuates from year to year in accordance with the variability of climatic conditions in the basin of the lake. Since the thermal and water regime of Lake Baikal is changing under the influence of global warming, the omul populations are adapting to shifts in the rhythms of the functioning of the lake's ecosystem. The purpose of this work is to analyze changes in the current ecological and morphological composition of spawning stocks of omul on the example of the posolskaya population in connection with the recorded changes in the timing of its migration for spawning in the 2000s. To analyze the nature of the variability in the timing and dynamics of spawning migration in 2009–2019, we used data from calendar records of the catch by a fixed river seine of mature individuals entering spawning rivers – tributaries of Posolsky Sor Bay. For ecological and morphological analysis, we used data on the morphometry of the omul that entered the Bolshaya Rechka River (one of the main tributaries of the Posolsky Sor. Bay) in different periods of the spawning season of 2020. The results of measurements of spawning migrants in 2020 indicate that, against the background of a general delay in the timing of migration, the dynamics of the morpho-ecological composition of spawning shoals is identical to that in the 1960s and 1980s and is typical for the population under the study. At the same time, data on the morphometry of fish that entered the river in different periods of the spawning season of 2020 indicates a change in the ecological and morphological structure of the population, namely, the quantitative ratio of spawning migrants from various subpopulations changes towards the predominance of "pelagic predators" – inhabitants of the deep-sea areas of Lake Baikal.