Питание окуневых рыб (Percidae) в малом озере бассейна Онежского озера

Abstract

The article s focuses on studying the fish nutrition, which is one of the ways to identify the patterns of fish onto- and phylogenesis, as well as the patterns of fish abundance and using food resources in the water bodies. Nutrition determines the key physiological and biochemical reactions in the fish body in a qualitative and quantitative sense, which finally affects the growth of both individual organisms and the entire population. The results of these studies are of practical importance in the work of fish protection authorities. Information about the fish feeding in the small water bodies of Lake Onega basin is practically absent in the literature. There are presented the results of the studies carried out within the framework of forecasting and economic and contractual issues of the Northern Water Problems Institute of the Karelian Research Centre of the Russian Academy of Sciences (NWPI KarRC RAS) and Petrozavodsk State University (PetrSU) on assessing the nutrition of perch species (perch, ruff) in the lakes of the Konchezero group (South Karelia) - the lower reaches of the river Shuya belonging to the catchment area of Lake Onega. The work was carried out by the specialists of the NWPI KarRC RAS in 2018–2020. The main hydrological and ichthyological indicators of Lake Urozero have been studied. It is found that in the diet of perch in Lake Urosero there appear larvae Chironomidae, Ephemeroptera and aerial insects, and the latter having the maximum index of relative importance. The diet of ruff caught in Lake Urozero differs widely: along with benthic organisms fish eggs were also present. Ruff’s nutrition is more abundant: the index of filling its stomach averages 225.3 0/000 against 51.2 0/000 in perch. Perch longer than 13 cm is a typical ichthyophag in Lake Urosero. It is typical for the Karelian lakes that the transition of perch to predation is ob-served when reaching the size (on average) 15 cm.