Rybohospodars'ka nauka Ukrayiny (Fisheries Science of Ukraine)

29-38

Authors: P. Shekk, M. Burgaz

Purpose. The development of the technology of the controlled rearing of marine fish remains one of the priority strategic trends of development of national mariculture. A study of the possibility of using polyculture for cage culture has a particular interest. Joint cultivation of several species of fish in the same cage, as practice of fish farming has demonstrated, does not have a tangible positive effect. At the same time, the use of cages of special design can provide significant additional fish products through the use of additional aquaculture objects. The ecological state of water areas, where the cages are located, is of great importance. High fish stocking density and the use of artificial feeds can serve as a source of powerful biogenic and organic pollution, which is especially important for shallow water areas with weak water exchange. The purpose of the study is to develop the methods for joint fish production in cage mariculture capable to provide high fish production and to weaken organic pollution of shallow water areas where cage farms are located. Methodology. The studies were conducted in 1999 and 2004. Cages of special design (internal 10 m3 and external 18.75 m3) installed in the brackish Shabolat Lagoon were used for rearing, steelhead trout, haarder, grass goby and round goby in polyculture. The standard aquaculture research methods were used. For express-analysis of environment hydrochemical parameters in cage location area the following devices were used: "ECOTEST-2000 T" (О2, NO2, NO3, NH4, CO2, phosphates, pH); termooksimetr "АJА-101М" (Т; О2); "pH meter-150 M); Refractometer "ATAGO-100" (salinity and water density). Findings. The results of marine fish cultivation in cages in polyculture in the shallow Shabolat lagoon are presented. It has been shown that joint cultivation of salmon, mullet and gobies in specially designed cages in shallow marine lagoons allows using artificial and natural feeds more fully and provides a high yield of commercial fish that results in significant additional products with a decrease in pollution level of the water area where the cages are installed. Originality. An original method for rearing marine fish in polyculture in specially designed cages has been developed. The perspective of culturing salmon, mullet and gobies in the polyculture has been demonstrated experimentally. The proposed technology ensures high efficiency of cage mariculture, allows getting additional production through the use of additional facilities and a reduction in the level of organic pollution in shallow water areas where cage farms are located. Practical value. The results of the study can be used to create cage mariculture farms in shallow seaside lagoons. Creating marine fish polyculture in specially designed cages will increase the efficiency of cultivation, reduce feed costs and reduce pollution in shallow water areas.

49-59

Authors: P. Shekk, Iu. Astafurov

Purpose. To study the effect of diet and water flow composition on the manifestations of cannibalism of shrimp Macrobrachium nipponense during rearing under controlled conditions. Methodology. The material for the work was shrimp fry with a length 2.0-3.5 cm and weight 1.5-3.0 g, caught in autumn 2016 in ponds of the lower reaches of the Dniester river. The shrimp were kept in tanks of the recirculation system with a volume of 0.3 m3. The temperature regime, light (period and intensity), and other environmental parameters were maintained in accordance with the specified parameters. Weighing was carried out on an AXISAD-50 electronic balance with an accuracy of 0.001 g. The length was measured with a ruler or with a caliper. In chronic experiments, two groups of shrimps were kept at the stocking density of 3 ind./L, temperature of 26-29°C and other equal conditions in tanks of a recirculating system. The diet of the first group consisted of animal food (bloodworm, fish, squid, snail, tubule, artemia), the second group was fed by plant feeds (cereals, vegetables, spinach, nuts, alfalfa, rice, chickpeas). Maturation of females in the second group was not observed. At the same time, cases of aggressive behavior were rare, and cannibalism was not observed, which ensured 100% survival. In the second series of experiments, shrimp were kept in fattening tanks at stocking density of 2 ind./L and a ratio ♂♂: ♀♀ - 1: 4. The diet of shrimp consisted of animal and plant feeds (1: 1). During the 30 days of the experiment, the water temperature was maintained at 26.0 ± 0.5 °C, the photoperiod was 12 hours light, 12 hours dark. Findings. The shrimp, which received animal food, grew faster. 20% of the females formed eggs. At the same time, their aggressiveness was high, which led to the loss due to injuries and cannibalism of 40% of the individuals. The shrimp, which received vegetable food, grew slower. Their final weight and size were significantly lower (P> 0.95) than those of shrimps of the first group with similar initial parameters. In the tank No. 1, a lateral flow of moderate force was created. Shrimps formed a sparse aggregation in the center of the tank avoiding the current. They did not take refuge, did not show aggression towards each other and did not protect their territory. In the tank No. 2, with similar conditions, there was no lateral flow. Shrimps were distributed evenly in the tank, took refuge and protected their territory, were aggressive towards other individuals, often entering into fights with them. With similar size and weight characteristics of shrimp in both cultivation variants (the difference is not significant P <0.95), no loss was observed in the first case, while it was 20% in the second case. Originality. For the first time, it was shown that the diet composition affects the growth, behavior and survival of M. nipponense shrimp. The use of vegetable feeds reduced aggressiveness and improved shrimp survival. Animal food increased the intensity of growth, ensured maturation of females, but increased the loss of shrimp due to cannibalism. Cultivation of shrimp in a tank with lateral flow of moderate force reduced traumatism and the loss of individuals due to aggressive behavior, with similar size and weight parameters. Practical value. Shrimp Macrobrachium nipponense is a promising object of aquaculture in the southern Ukraine. Increasing the yield of marketable production is an important aspect ensuring profitability of production. In this regard, the development of the methods, which allow reducing aggressiveness and increase the survival of shrimps in conditions of marketable cultivation is of great practical importance.

68-77

Authors: K. Heina, M. Koziy

Purpose. To analyze the mesonephros structure in the bream (Abramis brama Linnaeus, 1758) during its spawning migration, to determine the perspective of the use of microanatomical monitoring data in fisheries practice for assessing the functional status of fish. Methodology. Collection of ichthyological material was carried out using permit documents of the Institute of Fisheries NAAS of Ukraine, while their processing was done at the Department of Aquatic Bioresources and Aquaculture of the Kherson State Agricultural University. Ichthyological material was collected using gill nets, fyke nets, beach seines. Monitoring stations were located along the spawning migration run of the bream from the Dnieper lagoon to the plavni system of the Dnieper River. Field and laboratory processing of the material was done using author’s equipment and original methods specially designed for histological diagnostics of tissues of aquatic animals. Findings. The basis of the adaptation of bream kidneys to waters of different salinities us structural irregularity of nephrons expressed in the size and structure of renal corpuscles and convoluted tubules. Significant fluctuations of osmolarity parameters within the lower Dnieper area have significant effects on changes in the structure and function of nephrogenic tissue in form of the reduction in the diameter of Boumen-Shumliansky capsule by 9.0 µm. Changes of the Boumen-Shumliansky capsule diameter in fish with moderate mineralization is the range of 6.0 and 4.0 µm. The reduction in the height of epitheliocytes of proximal convoluted tubules by 3.0; 2.0 and 4.0 µm also indicate on the reduction of the functional activity of the convolute. The fluctuations of nephrogenic and homeopathic tissue ratio have a balance nature that can be related to the redistribution of these components due to the appearance of an adaptation under the effect of chloride-ions. The dislocation of ion-transporting cells near the blood vessels and around tubule epitheliocytes indicate on the participation of mesonephros in ion-regulating processes by increasing the resistance to changes in the osmolarity of the medium. The functional activity of a nephron changes when the osmolarity in bream mesonephros decreases that is manifested as a reduction in the diameter of renal corpuscles and height of the epithelium of proximal convoluted tubules. Originality. The detailed microanatomical analysis of mesonephros structure of mature bream of the Dnieper-Bug mouth system has been performed for the first time. The existing information on the taxonomic peculiarities of the transformation of nephrogenic tissue of fish in the conditions of spawning migration has been significantly elaborated and updated. Practical value. The actual information gives an opportunity to use the obtained material not only in morphophysiological studies but also in the practice of ichthyology and aquaculture in relation to the existing problem of the reduction in the life status of individual fish that results in the reduction of the stock of valuable commercial species, which formed partially migratory forms in the delta areas of river ecosystems.

99-113

Authors: I. Kononenko

Purpose. To develop the optimum composition of a cryoprotective solution for freezing sterlet sperm with the use of new and standard constituents and compare the results of the fertilization of eggs with sperm frozen by different ways and in different media. To analyze the results of keeping sterlet males in simulated conditions of natural spawning and to assess the quality of sexual products obtained during early spawning periods in comparison with natural ones. Methodology. The tasks set for the optimization of cryoprotective media for freezing sterlet sperm were solved according to generally accepted cryobiology methods and in accordance with Kopyeyka Ye. F. recommendations. The works with brооd sterlet were conducted in accordance with the generally accepted methods of sturgeon breeding and recommendations for natural spawning modeling. Findings. The studies demonstrated a positive effect of creatine, the introduction of which into the solution allowed increasing the cryoprotection of sperm from damaging factors of cryopreservation. During low-temperature freezing of sperm by different ways, the best results were obtained when freezing sperm in samples of smallest volume — granules that was evidenced by the number of live thawed spermatozoa, fertilization rates of eggs and the number of developing embryos. The simulation of the conditions of natural spawning allowed obtaining high-quality sexual products from sterlet males earlier in comparison with natural spawning periods, freezing them and fertilizing eggs after several weeks of storage. Originality. Among a variety of substances used in cryobiology for the optimization of the composition of protective solutions, positive results were tested and obtained with the use of creatine. Optimization of the cryopreservation solution composition was carried out using sterlet sperm obtained at early spawning terms compared to the natural ones. Practical value. The obtained results can be used in the conditions of hatcheries for obtaining sterlet offspring both for market and for the restoration of their populations in natural water bodies. In addition, the obtained results are the basis for further studies on the development of optimum composition of cryoprotective media for freezing sterlet sperm.