Behavioural pattern in cyprinid fish below a weir as detedted by radio telemetry

Changes in the behaviour of cyprinids belonging to different ecology groups were observed below a weir that was restricting their upstream migrations during the spawning period May-July. Politions of chub Leuciscus cephalus (L.). Prussian carp Carrasius auratus gifielio (Bloch 1783), bream Abramis brama (L.) and White bream Blicca bjoerkna (L.) were recorded every 12 min over a 24-h period using an automatic data Logger (ALS) in the upper Elbe River, Czech Republic. For all observed species, two activity peaks occurred; however, the interspecies timing of these peaks differed. Peak times for chub, bream and White bream occurred at night and during daylight, whereas Prussian carp was active mostly at night. Specimens belonging to the rheophilous group suggested more efficient behavioural tactics in passing the weir, staying below the obstacle one month longer than did eurytopic species.