Some pecularities of cultivation of table paddlefish (Polyodon spathula Walbaum, 1792) in ponds of the Forest-Steppe and Polissiya of Ukraine

摘要

Purpose. To investigate the growth characteristics and determine the productivity of paddlefish grown to marketable weight in ponds of the Forest-steppe and Polesia of Ukraine.Methodology. The cultivation of the North American zooplanktophage, a representative of sturgeons, the paddlefish, was carried out in polyculture with cyprinids in ponds with areas ranging from 0.2 to 74.0 ha with the use of semi-intensive and extensive technologies. The stocking density of age-1-2 paddlefish with an average weight of 86.5 to 1017.0 g varied within 59-150 ind./ha with a total stocking density for all polyculture objects of 515-2402 ind./ha. Intensification measures included application of traditional organic fertilizers into ponds and feeding of carp with feed mixtures based on wastes from the processing of agricultural raw materials of vegetable origin in some ponds. Studies of the intensity of development of the natural food supply of ponds and physicochemical parameters of the aquatic environment were carried out according to the methods generally accepted in hydrobiology and hydrochemistry. The peculiarities of fish growth were studied with the use of common ichthyological methods for the dynamics of body weight gains in absolute and relative values.Findings. The environmental conditions in ponds during most of the growing period met the biological requirements of the studied aquaculture objects. A periodic decrease in the oxygen concentration in water to 1.5-2.2 mg O2/dm3 was noted, which could have a negative effect on fish growth. The average seasonal biomass of zooplankon in ponds was in the range of 3.8-5.8 g/m3 with predominance of Cladocera and Copepoda. As a result, paddlefish production was 48.8-256.4 kg/ha in total fish production in ponds ranging from 502.3 to 1249.0 kg/ha. Average seasonal weight gain of paddlefish, depending on growing conditions, was 0.84-1.49 kg. The maximum daily increments of this species were observed during the first half of the growing period at a water temperature of 18-25°C, when zooplankton biomass in ponds varied within 3.7-17.4 g/m3.Originality. New data have been obtained on the peculiarities of paddlefish growth in the conditions of ponds of the Forest-steppe and Polesia of Ukraine.Practical value. The study results are an integral part of the database for the development of improved sturgeon breeding technologies in Ukraine.