In the spring, after opening up thousands of small sors, the fish rush to feed from the Ob Bay to the vast floodplain-sor system of the Ob. This movement is called "vonz", which in translation from the Khanty language means "the movement of fish against the current". The peled begins the ascent first, followed by other whitefish, and the burbot completes the move. Whitefish preparing for reproduction are distributed more widely across the Ob floodplain.
Whitefish feel more comfortable in years of high flood waters: the longer the floodplain does not dry out, the more the fish eat. The accumulated fat serves as energy for a long migration to spawning grounds. The fertility of individuals and the quality of the laid eggs directly depend on good fattening.
Scientists from the Tyumen branch of VNIRO work on their own vessel, which allows them to be based in places where the collected information will be as representative as possible. The most suitable place is the village of Yambura in the Priuralsky district. Here the Ob narrows, and ichthyologists can record the passage of the maximum number of fish. Science has been present in this territory for more than 55 years, which allows them to record the dynamics of the state of populations and the number of stocks of all species.
During expeditionary work, scientists from the Tyumen branch of VNIRO conduct control catches and, on a research vessel, perform biological analysis of the caught individuals and mass measurements, and conduct primary processing of hydrobiological samples.
The complex studies also include an assessment of the number of fish, their concentration and distribution. For this, scientists use a modern hydroacoustic complex. Echo sounder surveys are carried out at different points of the river.
At the same time, specialists are recording the state of the habitat - they are taking hydrobiological samples: zoo- and phytoplankton, zoobenthos, as well as hydrochemical ones - water samples.
In addition, the Tyumen branch of VNIRO continues to replenish the genetic database of northern fish. The collected ichthyological material will be used for molecular genetic research.
Press service of VNIRO
