Movements and habitat use of wild and stocked juvenile chub, Leuciscus cephalus (L.), in a small lowland river

Stocking is a widespread management activity in inland fisheries, but the efficacy of such fishery enhancement measures is poorly understood. Radio-telemetry was used to compare the movements and habitat selection of stocked, juvenile chub, Leuciscus cephalus (L.), with those of wild individuals in a small river in Eastern England. Thirty-two wild juvenile chub (total for 2005 and 2006 combined) and 12 stocked, 1+ chub (2006) were surgically implanted with radio-tags and tracked once per day for 1 month. Stocked chub did not disperse immediately after release, there was no evidence of reduced survival of stocked chub, and neither wild nor stocked chub were permanently displaced downstream of the study reach by high flows. Linear ranges of wild chub were, however, smaller than for stocked chub, movements were more frequent and larger for stocked fish (particularly during elevated flows), and differences in habitat use were found. The short-term success of stocking cyprinids was demonstrated, whilst emphasising behavioural (movements and habitat use) differences between hatchery fish and wild counterparts, and the necessity for long-term monitoring.