Rybohospodars'ka nauka Ukrayiny (Fisheries Science of Ukraine)

20-30

Authors: N. Tson

Purpose. To investigate the potential of zooplankton productivity in aquatic ecosystems under experimental conditions of the microcosms with the use of the green fertilizer (vetch-oat grass) and Ekovital. Methodology. The study was conducted under the conditions of model ecosystems (microcosms) installed in fish-breeding ponds. We used a complex of intensification measures (enhancement, inoculation of vetch-oat seed mixture (1:1) with Ekovital at quantities of 1.4; 2.9; 4.3 ml/kg (variants D1, D2, D3), followed by sowing the pond beds with the vetch-oat mixture (1:1), growing of vetch-oat grass for the green fertilizer). The seeds were sown at a ratio of 70 kg of grains for 1 ha of ponds area. The first control variant (K1) — without green fertilizer and without preparation. The second control version (K2) vetch-oat seeds were soaked in the corresponding quantity of water without preparation and after they were sown on the pond bed. The preparation Ekovital contains specific nitrogen-fixing nodule Rhizobium leguminosarum and phosphorus mobilizing Bacillus megaterium-6 bacteria. Hydrochemical, hydrobiological, fisheries, and statistical studies were conducted according to standard methods. Findings. It was found that the application of Ekovital in a combination with enhancement activities gives an opportunity to obtain a green fertilizer of up to 1.03 ± 0.08 t/ha during 40 days for increasing pond ecosystem productivity. The stimulation of zooplankton development gave an opportunity to obtain the maximum biomass of 9.85–31.78 g/m3 that was 4–16 times higher than in that in the control — 2.54–3.30 g/m3. The mean values of zooplankton biomass in the experiments were 4.30–9.17 g/m3, that was 3-9 times higher than those in the control — 1.06–1.40 g/m3. The experimental variants showed a tendency for increasing the share of cladoceran crustaceans. The production of zooplankton organisms was increased to 1834.8 kg/ha — the level of the most productive breeding ponds of the forest-steppe zone of Ukraine. The potential of natural fish productivity of an aquatic ecosystem based on zooplankton when applying the green fertilizer (vetch-oat grass) and Ekovital showed a 3–7 time increase compared to the control. The maximum potential natural fish productivity based on zooplankton was achieved at the level of 152.90 ± 85.25 kg/ha in the variant D2. Originality. For the first time we presented the results of the studies of zooplankton community productivity in fish-breeding ponds with the use of the green fertilizer of vetch-oat grass and bacterial preparation Ekovital under the conditions of model ponds ecosystems (microcosms). Practical value. The received results are the basis for further studies on the use of a method for increasing natural fish productivity in fish-breeding ponds with the use of a green fertilizer such as vetch-oat grass and Ekovital. Key words: green manure, zooplankton, Ekovital, natural forage, fish-breeding ponds, natural fish productivity.

41-50

Authors: I. Hrytsyniak; A. Mariutsa; S. Tarasiuk

Purpose. To investigate the specificity of the genetic structure, intra- and interpopulation genetic variability of the pedigree stocks of bighead carp in different fish farming zones using DNA markers (ISSR-PCR). Methodology. To investigate the specificity of the genetic structure we used a PCR (ISSR-PCR) method with appropriately selected primers. Findings. As a result of the study of the pedigree stocks of bighead carp, we carried out an analysis of the genetic structure by using three microsatellite DNA loci (CTC)6C, (GAG)6C, (AGC)6G. The investigated populations accumulated a reserve of the genotypic variability in different parts of microsatellite loci. The identified specific properties among the investigated bighead carp populations can characterize the heterozygosity degree of the stocks reared in these fish farms. The variations in the detected amplicons are sufficient for separating the individuals of breeding stocks, or, if the work is carried out with a group of brood fish, to select parent pairs for increasing the genetic diversity. The described variability of the genetic structure by specific gene sites and distribution of markers in fish stocks indicate on significant level of genetic variability that is a basis for determining the level of their adaptability in the process of artificial selection in fish farms of different forms of ownership. Originality. We detected the peculiarities of the genetic structure, the level of genetic variation of the pedigree stocks of bighead carp in different fish farming zones with the use of DNA. For the first time we obtained new data on the specificity of the genetic structure based on PCR, which contribute to the detection of the specific mechanisms of maintaining the relative stability of bighead carp genetic pool and allow controlling the specificity of their genetic structure. Practical value. The practical value of the study is to propose a method of the genetic control of bighead carp populations by applying a PCR that allows performing an analysis of the genetic structure of the stocks and realizing the genetic information on early stages of the breeding process. Key words: molecular genetic methods, DNA markers, bighead carp, genetic structure, PCR.

61-81

Authors: А. Нulaі; O. Zhukorskiy; V. Нulaі; N. Tkachuk

Purpose. To determine the effect of skin secretions in Percidae family of fish (Sander lucioperca, Perca fluviatilis) on the cultures of pathogenic E. rhusiopathiae bacteria. Methodology. Filter paper was placed on the skin of live fish; after 1 minute it was removed, and the extraction of water-soluble components in the rate of 0.1 cm3 of water per 1 cm2 area of the paper was carried out. The resulting solutions of the secretions of fish skin glands were sterilized by vacuum filtration through the filters with a pore diameter <0.2 micrometers. The cultures of E. rhusiopathiae bacteria, which were used for testing, were grown in brain-heart broth for 48 hours at a temperature of +36.7 ± 0.3 °C. The test samples contained E. rhusiopathiae cultures and fish skin secretions in 1:10, 1:100, 1:1000 and 1:10000 dilutions. The control samples contained a similar ratio of sterile water and cultures of the experimental bacteria type. The content of E. rhusiopathiae cells in the experimental and control samples was determined after 48 hours, the samples were stored at a temperature of +18... +20 °C. Findings. The presence of water-soluble extracts of skin secretions obtained from Percidae family of freshwater fish in the environment causes an increase in the density of E. rhusiopathiae bacteria cultures. The degree of the detected stimulating effect of E. rhusiopathiae directly depend on the concentration of the secretions of fish skin glands in the experimental samples. Under the conditions of freshwater ecosystems, such fish as S. lucioperca and P. fluviatilis and E. rhusiopathiae bacteria may form biocenotical relations of the trophic, topical and phoric types. Originality. The quantitative data proving the biological activity of skin secretions in Percidae family of fish with regard to E. rhusiopathiae pathogenic bacteria have been obtained for the first time. Practical Value. One of the factors contributing to E. rhusiopathiae bacteria staying in freshwater conditions for a long time can be their biocenotical relations with the components of freshwater biocenoses, including such fish as S. lucioperca and P. fluviatilis. When carrying out measures aimed at preventing and eliminating the outbreaks of infections caused by E. rhusiopathiae, it is necessary to consider the possibility of the persistence of these pathogenic bacteria on the skin of freshwater fish. Key words: Sander lucioperca, Perca fluviatilis, skin secretions, biological activity, Erysipelothrix rhusiopathiae, stimulating effect.

81-88

Authors: O. Shkarupa

Purpose. To substantiate theoretically the optimum safety factors of fishing materials used for the construction of fishing gears that allow reducing the material consumption of these gears and keep them for a long time operation. To select the optimum color of polyamide materials with the lowest loss of strength. Methods. The choice of the materials for the tests was based on the selection of the materials, which are most often used for active and passive fishing gears. Acid dyes were used to dye the materials. Dying was carried out in accordance with the technological instructions. The experiments were conducted at the Department of "Industrial Fishery" of the Kerch Sea Institute. The obtained results of all tests were processed using statistical method of random variables according to Sturges method. Findings. The dying reduces the initial strength of the material by 10% and increases its service life. A relationship was established between the loss of nylon material strength and color as well as insolation time. The lowest loss of strength was observed in materials dyed in brown color. We developed the equations of relationships allowing adjusting the norms of the rate of the wearing of fishing gears. The safety factor of 4.62 was obtained experimentally and this value ensures the uninterrupted usability of a fishing gear during the exploitation period. Originality. Based on the system integrated experimental and theoretical studies of the loss of strength of thread and netting materials, for the first time we developed the mathematical relationship for the loss of strength of kapron fishing materials depending on the time of insolation that allows predicting the degree of their wearing during the exploitation of various types of fishing gears. Practical value. The obtained equations of the relationship between the loss of strength of fish netting materials and the time of exposure to sunlight are used in the calculation of wearing rates for beach seines, hoop nets, and fish net cages. The use of the recommended materials with the estimated safety factor will allow increasing the service life of fishing gears. Key words: Netting, fishing threads, acid dyes, standards of wear, coefficient of durability, fishing gears.