27 October 2025

Ichthyological research has been completed in the Northern Sosva River

Specialists from the Fisheries Ecology Laboratory of the Tyumen Branch of the Russian State Research Center "All-Russian Research Institute of Fisheries and Oceanography" (VNIRO) have returned from a long expedition along the Severnaya Sosva River, where they studied the spawning and wintering runs of whitefish and the feeding and wintering migrations of common fish species.

The fisheries research in the largest spawning river in the Ob-Irtysh basin lasted two months. The ichthyologists were based on their own vessel, from which they traveled daily to monitoring stations.

As part of the research, the specialists conducted test catches, performed biological analysis of over a thousand fish, and mass measurements of over seven thousand individuals. Catch trends in the river remained unchanged compared to last year. However, this season, the specialists recorded several times more nelma, primarily juveniles.

To assess the state of the aquatic environment and food supply in the river, samples of water, zoobenthos, phytoplankton, and zooplankton were collected at various points.

After office processing of the collected material, specialists will determine the size, age, and sex structure of the migratory ichthyofauna, its species composition, and calculate the abundance and biomass of aquatic bioresources.

The data obtained will be used to calculate the total allowable and recommended catches for the fish species studied.

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VNIRO Press Service