ASSESSMENT OF THE DEVELOPMЕNT OF POND FORAGE BASE WHEN REARING CARP (CYPRINUS CARPIO CARPIO) FISH SEEDS AT FISH FARM ?MERKURIY?

Purpose. To assess the development of main components of natural forage base in nursery ponds during the period of rearing the carp fish seeds in monoculture. Methodology. Hydrobiological (bacterioplankton, phytoplankton, zooplankton, zoobenthos) and hydrochemical samples have been collected and processes according to generally accepted methods. Findings. Qualitative and quantitative parameters of the development of bacterio-, phyto-, zooplankton and zoobenthos in nursery ponds have been studied when rearing young-of-the-year Lubin few scale carp, Antoninsko-Zozulenets carp and their reciprocal crosses in monoculture (50 thousand fish/ha). General water mineralization in ponds was 292.7?315.7 mg/dm3 and according to O.A. Alekin’s classification, pond water belonged to hydrocarbonate class of calcium group. Water pH was 7.4?7.5. Permanganate values were 12.5?14.9 mgO/dm3. On average, average ammonium nitrogen content, nitrite nitrogen and nitrate nitrogen, mineral phosphorus, total iron did not exceed normative values. Qualitative and quantitative parameters of phyto-, bacterio-, zooplankton of nursery ponds have been studied. The seasonal development of phytoplankton was within 15.96?20.88 mg/dm3 with the predominance of Chlorococcales in the floristic spectrum. The development of bacterioplankton was within 5.08?5.81 mg/dm3. Zooplankton was dominated by cladoceran-copepod complex with average seasonal values of 5.27?17.20 g/m3. Zoobenthos was formed of Diptera larvae (Chironomidae and Chaoboridae) with average seasonal biomasses of 0.51?1.8 g/m2. According to saprobic parameters, pond water belonged to β-mesosabrobic zone and corresponded to the water quality class II (“clean enough” category). Fish productivity of nursery ponds was within 617.2?815.2 kg/ha; output of carp young-of-the-year was within 39.82?43.56%, mean weight of young-of-the-year was 31.0?39.3 g. Originality. For the first time we carried out a comprehensive assessment of the natural forage base in nursery ponds when rearing carp fish seeds in the conditions of forest-steppe zone of Vinnitsa region at the fish farm “Merkuriy”. Practical value. The obtained data allow rearing high quality young-of-the-year Lubin few scale carp, Antoninsko-Zozulenets carp and their reciprocal crosses.