Feeding habits of the river perch (Perca fluviatilis L.) found in Karelian lake and river waters

A comparative analysis of the nutrition content consumed by the river perch (Percafluviatilis) in the lake and river waters of Karelia is submitted. It was revealed that in the waters of salmon river Suna the river perch (Perca fluviatilis L.) consumed smaller amounts of zooplankton than in the waters of Vokhtozero lake. The fish ration along with the typical lake provision- roach and ablet - was supplemented by river species - slimy sculpin. It is established that despite a rather high percent of empty stomachs (41%) in perch inhabiting the flows of the Suna River the average index of stomach fullness amounts to (126 0/000). The maximum fullness indexes (up to 14 8 9 0/000) in perch dieting in river waters were higher in comparison with the ones dieting in the lake conditions (average - 8 8 0/000; maximum - 4 8 2 0/000). We came to a conclusion that such differences in the above provided indicators are explained by a big amount of fish in the perch’s food ratio.