TELEMETRIC OBSERVATION OF FISH DISPERSION IN THE MOHELNO RESERVOIR, CZECH-REPUBLIC

The spatial dispersion of adult common bream Abramis brama, chub Leuci scus cephalus, asp Aspius aspius and carp Cyprinus carpio was studied in the Mohelno Reservoir using ultrasonic telemetry and simultaneous h ydroacoustic measurements during May 1988. The reservoir is an importa nt part of a hydroelectric and nuclear power system, with extremely hi gh daily water level fluctations reaching up to 8 - 10 m. Regardless o f the place where the tagged specimens were released (in the upper and lower parts of reservoir), all these fish concentrated finally on the lower part of the reservoir within 1 - 3 days and did not leave it du ring the entire study period (6 days). This distribution is probably r elated to the relatively stabile hydrology in this area compared with other parts of the reservoir.