Influence of rearing method on ide Leuciscus idus L. juvenile survival under pike and pikeperch predation

Nase Chondrostoma nasus L., once one of the most common fish species in the upper reaches of central European rivers, is now considered endangered throughout its natural range. Since 2000 the Department of Ichthyobiology and Fisheries, Warsaw Agricultural University, has co-operated with the Polish Anglers Association in Krosno to study the effects of river restocking with pond‐farmed nase juveniles. The experiment is carried out on Wislok River, where nase was very twenty years ago but has now completely disappeared. Selected parts of the river are stocked with tagged, one‐summer and 1 year‐old juveniles. Changes in nase occurrence, and their growth and foraging behaviour have been analysed.