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Radio-telemetry shows differences in the behaviour of wild and hatchery-reared European grayling Thymallus thymallus
P Horká1,2, P Horký3, T Randák4
1Department of Ecology, Charles University, Faculty of Science, Viničná 7, 128 44 Prague 2, Czech Republic.
Abstract:
Juvenile wild and hatchery-reared European grayling Thymallus thymallus were tagged with radio-transmitters and tracked in the Blanice River, River Elbe catchment, Czech Republic, to study their behavioural response to stocking and environmental variation. Both wild and hatchery-reared T. thymallus increased their diel movements and home range with increasing light intensity, flow, temperature and turbidity, but the characteristics of their responses differed. Environmental variables influenced the movement of wild T. thymallus up to a specific threshold, whereas no such threshold was observed in hatchery-reared T. thymallus. Hatchery-reared fish displayed greater total migration distance over the study period (total migration) than did wild fish, which was caused mainly by their dispersal in the downstream direction.
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