MONITORING STUDIES OF THE KONDOPOZHSKAYA GUBA OF ONEZHSKOE LAKE STATE IN THE CONDITIONS OF FISH FARMING

Abstract

The results of the study of the hydrological, hydrochemical and hydrobiological state of Kondopoga Bay of Lake Onega affected by commercial trout pond farming (production rate is 5540 t/year in 7 nursery ponds) are reported. The hydrological indices of Kondopoga Bay of Lake Onega (area (243 km2, average depth 21 m, maximum depth 82 m, arbitrary water exchange 0.45, etc.) meet trout pond farming requirements. Its hydrochemical indices (percentages of oxygen, nutrients, suspended particles, etc,) show that the bay is of mesotrophic type, in which water quality meets the hydrochemical composition and maximum allowable concentration (MAC) requirements for trout production. The development level of quantitative zooplankton shows that the water masses in the water zone studied are oligotrophic. The water is characterized as b-mesosaprobic, based on its saprobity index of 1.79-1.81, which is consistent with quality class 3 (mildly polluted water). The bay corresponds to an oligo-mesotrophic type on a nutrient content scale, as indicated by the development and species composition of benthic fauna, and a mesosaprobic type, as indicated by the saprobity index (Pantle–Bukk–3.05). The nutrient load exerted by the trout farm is estimated and the scope of trout farming in the bay is recalculated. It is noted that the long-term management of fish farms, which produce great amounts of trout, requires monitoring of the bay once in three years.