Feeding of small-sized European perch, Perca fluviatilis, in a littoral zone of a restored lake

The study focuses on the feeding of small-sized European perch, Perca fluviatilis, in a lake after stocking with predatory fish and their effect on zooplankton in view of ongoing lake restoration. It has been assumed that predator-prey interactions should lead to increased trophic activity of perch in the littoral zone. The studies were carried out from June to October 2008. The results of catches indicated that small perch were eliminated from open water and were recorded only in the littoral zone of the lake. In their diet, a total of 19 food items were found, primarily represented by invertebrates: Cladocera, Copepoda, Diptera and sporadically Rotifera. Herbivorous forms, i.e. Calanoida or Daphnia sp., were frequently picked as food items (F = 40–50%). The most important food component was zooplankton, which accounted, on average, for 90% of the total numbers of consumed animals and nearly 65% in terms of food mass. Cladocera constituted for a larger part of the selected food items than Copepoda, but only in late spring and partly in summer. Significant feeding pressure on large filterfeeders of the genus Daphnia is expected only periodically.