Opening of navigation in Lake Baikal

From 21 to 27 May 2023, a research expedition was carried out to study the condition of the Baikal omul population in the waters of the Selenga Shallow Waters. The hydroacoustic complex “Echo-Baikal” developed at Limnological Institute performed an acoustic survey of omul distribution along a standard transect scheme with a total length of 105 nautical miles. To verify acoustic data, we conducted trawls using a pelagic trawl of different depths and sampled fish for biological analysis. Further future-oriented research of eDNA was performed. The expeditionary works were carried out within the State assignment “Study of the impact of seasonal and long-term fluctuations in the level of Baikal on the biotic and abiotic compounds of the littoral zone of the lake and mixing zones of river and lake waters” (project № 0279-2021-0016) (led by A. Fedotov).

The work is aimed to study the dynamics of the Baikal omul population in the Selenga shallow water area using trawl-acoustic method and to estimate the number and sex-age structure of a feeding fish stock.

During the expedition, 205 km of hydroacoustic profiles were passed. Representative biological material was collected to determine sex-age structure of a feeding fish stock. Water samples were taken at sites with varying concentrations of fish to refine the methodology of quantitive omul distribution based on DNA analysis in water.

Some differences in omul distribution in comparison with the previous years were revealed. Thus, there was an increased migratory activity of omul accumulations. For a few hours omul accumulations changed their location up to tens of kilometers. In previous years, omul accumulations could not change their location during the day. Spatial structure of omul accumulations was characterized by sharp heterogeneity from conditionally "frequently occurring fish accumulations" to the areas with complete absence of accumulations.

Hydroacoustic research of omul in Middle and Northern Baikal will be continued in the next voyage of R/V "Vereshchagin", which will take place from May 30 to June 13, 2023.