Yield of fish juveniles of the nearshore areas of the Dnister River within the boundaries of the Ivano-Frankivsk region

Abstract

Purpose. Taking into account the unique ichthyological complex of the upper course of the Dniester River, the studies should be directed both at the structure of the ichthyofauna and at its quantitative parameters of the species structure, and fish with a special conservation status need special attention. Therefore, the purpose of our work was to determine the peculiarities of the current structural and functional organization of the ichthyocenosis of the Dniester River within the Ivano-Frankivsk region. Methodology. Quantitative assessment of fish juveniles was carried out using the area method. Fish juveniles were identified to the species level using A.F. Koblytska and Yu.V. Movchan identification keys. All fish, after some measurements, were released to the place where they were caught in an undamaged state and alive. After identification of fish species with a special conservation status, which were trapped into the fishing gear, they were immediately returned to their habitat without removing them from water. Findings. Fourteen fish species were observed in the community of fish juveniles on the nearshore areas of the Dniester River in the Ivano-Frankivsk region. According to the data of the analysis, following relative abundances of juvenile fish species were observed: vyrezub (40% of the total abundance), bleak (23% of the total abundance) and vimba (18% of the total abundance). The total relative abundance of fish juveniles with special conservation status in the total catch was 68%, which suggested the need to create additional zones in order to increase conservation measures. Given the high share of fish species with special conservation status, the assessment of species biodiversity in terms of biotope similarity is important. The area of Mariyampil village and floodplain coastal areas were characterized by the highest biodiversity in terms of species composition of ichthyofauna among the studied biotopes. The highest abundance of fish juveniles in absolute values was recorded in the mouth areas of the rivers, but its high values were achieved due to the juveniles of vyrezub. Also, this studied nearshore area was not characterized by a high biodiversity of ichthyofauna, which was confirmed by the Shannon-Weaver index at the level of 1.74. According to the results of our study, it can be stated that the nearshore areas of the mouth part of the rivers are important and unique for the formation of ichthyocenosis specifically for the vyrezub. Thus, it can be concluded that all analyzed stations were characterized by the presence of vyrezub, which allows classifying the studied area as important in terms of environmental protection. In view of the prevalence of juvenile vyrezub within the studied areas, protective measures are more important, which are aimed not only at ensuring control over the state of aquatic biological resources, but also at the organization of artificial replenishment of natural localities and the creation of new populations of this species with their purposeful acclimatization in specially selected ecological conditions of the water body. Originality. For the first time, the yield of fish juveniles in the nearshore areas of the Dniester River within the Ivano-Frankivsk Region was analyzed. The obtained data will be used to solve the problem of the preservation of species diversity and the abundance of fish species, which are valuable in terms of environmental protection. Practical value. As a result of the assessment of the current state of the ichthyofauna of the Dniester River within the limits of the Ivano-Frankivsk region, data were obtained regarding the natural localities of rare and endangered fish species in the specified area.

Keywords

• ichthyofauna
• dniester river
• protected species
• natural locality