The Influence of Abiotic Factors on Fish Distribution in Kaulakiai II (Kybartėliai) Water Rezervoir

The influence of abiotic factors on fish distribution in Kaulakiai II water reservoir is investigated in present master thesis. Object of research – fish communities of Kaulakiai II water reservoir, situated near Raseiniai. Aim of the research – to estimate the substantial abiotic factors and to evaluate their influence on fish distribution in Kaulakiai II water reservoir. To meet an aim these tasks were set: to estimate the most abundant fish species in reservoir; to estimate and map the structure of the bottom; to evaluate sensual indicators of alive fish during the experimental fishing; to value the quality of water in Kaulakiai II reservoir and to rate it according the standards applied for water quality in carp ponds; to detect peculiarities of fish distribution in water body and to exclude the substantial abiotic factors that have hold on fish distribution in Kaulakiai II (Kybartėliai) reservoir. Methods of research – logical literary analysis, hydro acoustic surveying, written quiz of local anglers, observational studies, mathematical modeling. Results: the Cyprinid fishes (11 species) were the most abundant in Kaulakiai II reservoir fish communities with overall 15 fish species resident. The bottom structure mainly was silt - 83,2 %, sand and oozy sand, respectively 4,6 and 12,2 %. Fish injures, parasites, diseases had no influence on fish distribution in Kaulakiai II reservoir during the research. Low oxygen concentrations were estimated at the bottom of reservoir, yet fish were observed in whole water body. Based on results, fish distribution in Kaulakiai II reservoir was saltatory – underwater structure (trees, weeds), bottom hardness and pool depth influenced fish distribution in Kaulakiai II reservoir the most. Water temperature was also a strong predictor of fish distribution. Other abiotic factors had weaker (atmospheric pressure, moon phase) or non existing (wind speed and direction, clarity of the water) correlation.Žemės ūkio akademijaVytauto Didžiojo universiteta