DIET OF EUROPEAN GRAYLING (THYMALLUS THYMALLUS L.) FROM RIVERS OF THE ZAKARPATTYA IN CURRENT CONDITIONS
Authors: A. Khandozhivska, S. Krazhan, A. Mruk, S. Koba
Number of views: 231
Purpose. Determination of the diet spectrum of European grayling (Thymallus thymallus), qualitative and quantitative composition of the gut content of age groups (2+, 1+, 0+) from Teresva and Tereblya Rivers of the Zakarpattia region.
Methodology. The initial material at a quantity of 28 multiple age individuals of European grayling was collected during field works in Zakarpattia rivers. The material was collected with the assistance of Zakarpattia Fish Protection Inspection. Fish were taken from poachers’ fishing nets in a fatal condition, then they were preserved in a 10% formalin solution. Processing of preserved material was conducted in laboratory conditions. The diet of multiple-age groups (2+, 1+, 0+) of European grayling from Teresva and Tereblya rivers of the Zakarpattia region was investigated.
Findings. It was found that European grayling consumed mainly benthic invertebrates, preferring amphibiotic organisms of Insecta class. Diptera, Trichoptera, Plecoptera, Coleoptera, Ephemeroptera, Odonata, and Amphipoda representatives were common in the diet of age-2+, 1+, 0+ fish. Gut fullness content index of young-of-the-year grayling with an average weight of 12,3 ± 0,72 g was in average 384,54 ± 114,01 %оо, age-2+ fish with an average weight of 29,53 ± 2,14 g – 177,75 ± 16,41 %оо, and age-3+ fish with an average weight of 91,4 ± 11,42 g – 168,49 ± 25,44 %оо, respectively.
Originality. Information on European grayling diet in the Zakarpattia rivers in current conditions is insufficient because this species in listed in the Red Book of Ukraine that limits obtaining the materials for its studies.
Practical value. The obtained data allow scientifically justified determining the stocking amounts of European grayling juveniles for increasing its natural populations in the rivers of Zakarpattia.
Key words: European grayling, diet, gut fullness index, Zakarpattia rivers.