Expedition for assessment of the state of Baikal omul stocks in the water area adjacent to the Selenga R. mouth, from May 27 till May 30, 2021

From May 27 till May 30, 2021, a hydroacoustic survey of the Selenga River fishing ground was jointly performed by Limnological Institute and Baikal affiliation of Federal State Budgetary Scientific Institution “VNIRO” from the board of the R/V “G. Yu. Vereshchagin”. The survey was performed using two hydroacoustic systems: Simrad EY-500 (performing frequency 70 kHz) and unit “Echo-Baikal” on the base of the echo-sounder Furuno FCV-1100 (performing frequencies 28 and 200 kHz). The research vessel moved according to the tack grid that had been planned before at the depths from 50 to 400 meters.

The hydroacoustic survey from the board of the R/V “G.Yu. Vereshchagin” was accompanied by continuous measurements of surface water temperature salt content. The measured values allowed recording a phenomenon of spring thermal bar while the vessel was moving, so a shallow water boundary of the distribution of Baikal omul feeding stock was localized.

The data will be processed and will allow assessing the stocks of Baikal omul in the study area. The specialists from Federal State Budgetary Scientific Institution “VNIRO” will do this work. The analysis of size composition of the feeding stock will allow to the specialists of LIN of RAS SB determining the general state of the population as well as assessing how it was influenced by previous low-water years.

We can conclude preliminarily that the omul distribution in the water area of Selenga shallow water corresponds to winter-spring one, mainly the specimens are concentrated at the depths of 150-250. Denser accumulations are observed in the zone of the underwater slope.