The usage of probiotic microorganisms in production technology of European grayling fish stock

Abstract

Abstract European grayling is a perspective object of a recreational fishing. In addition, the presence of this species in sufficient quantities in rivers has a positive influence on the formation of the recreational attractiveness of mountain regions, where tourism is one of the main sources of local communities existence. However, grayling stocks in the watercourses of Ukraine are significantly depleted nowadays, and populations are in a condition of lack, what has led to the inclusion of this species into the Red Book of Ukraine. Working out of biotechnologies of artificial reproduction of rare fish species in aquaculture conditions for the further reintroduction of the resulting offspring into natural water bodies takes an important place in the system of environmental protection measures to preserve biodiversity. After all, the reintroduction into nature of artificially obtained fish fry is one of the effective ways to restore the optimal number and structure of rare fish species natural populations, and this, in turn, will allow in the future to restore the limited exploitation of the stock of these fish species. One of the critical artificial fish reproduction technology links is the transfer of larvae to external nutrition. Namely on this stage the highest mortality rates are observed. The usage of live feeds as a starter fodder can significantly improve the situation. Forage organisms, in addition to having high nutritional value, can serve as delivering tools of various targeted products, including probiotics, to a fish larvae organism. The assessment of the usage of probiotic strain Lactobacillus casei IMV B-7280 feasibility is carried, and also the possibility of usage the culture Daphnia magna Straus, 1820 grown in the presence of trehalose lipids, within the technology of early feeding of the European grayling Thymallus thymallus (Linnaeus, 1758). It was shown that the larvae of the European grayling, which received investigated probiotic microorganisms strain, had 15% bigger weight on the final stages of feeding than the larvae of the control group. Introduction to the diet of grown-up grayling larvae of the culture Daphnia magna, previously received of common cultivation with microalgae Desmodesmus armatus (Chodat) E.H.Hegewald 2000 with addition of trehalose lipids, contributed to the reduction of larval mortality and the acceleration of their growth rate. Further improvement of proposed approaches of growing grayling fish planting material can be extrapolated to other fish species and in the future may be applicable in the process of growing rare fish species in conditions of farm aquaculture fish farms, what will allow them to be involved into environmental protection activities by placing appropriate orders. This, in its turn, will contribute to the stable development of communities in rural areas.