During the studies, research fellows and specialists at 12 monitoring points determined the nature of bottom sediments, measured depths, temperature, dissolved oxygen content, pH, mineralization, transparency; samples of phytoplankton, zooplankton and zoobenthos were collected to assess the food supply for fish.
To assess the state of commercial fish populations, 100 net sets were carried out, 20 fish species were noted in the catches, including pike perch, bream, pike, roach, perch, white bream, sabrefish, ide, rudd, vendace, signalfish, ruff, tench, white-eye, chub, asp, bersh, blue bream, crucian carp, bleak.
The length, weight, sex, stage of gonad maturity, degree of obesity and intestinal filling were determined in the caught fish, scales and fin rays were collected for subsequent study of the age of the fish. Samples were taken from some fish to assess the content of parasites in them, muscle tissue to determine the accumulation of toxicants, as well as the gastrointestinal tract for subsequent determination of the composition of the food bolus. The collected field hydrobiological and ichthyological material is in laboratory processing. A total of 4,344 fish specimens were measured, including 1,218 specimens with scales and fins taken to determine their age. In small-mesh nets, roach, perch, and white bream dominated the catches, while in large-mesh nets, bream and pike perch dominated.
This autumn, trips to the Megra River and its tributaries are planned to monitor the current state and numbers of natural populations of Atlantic salmon and brown trout, as well as to Lake Beloye to analyze the composition of industrial catches from drift and fixed nets.
Press Service of VNIRO