| Summary: | The relative performance of European grayling Thymallus thymallus reared
in a hatchery on commercial dry feed or in a pond with natural food and their wild
conspecifics, was assessed through recapture of tagged fish 5 months after their release
into the Blanice River, Czech Republic. One-year old pond and hatchery reared fish from a
resident broodstock were marked using Visible Implant Elastomer tags and released into 3
sections of river in May 2006. Wild one-year-old grayling were also tagged in these
sections on the same days. The ratio of hatchery reared, pond reared, and wild fish was
1:1:1 in all sections. The recapture rate (hatchery 14.9%, pond 22.1%, and wild 51.3%) and
site fidelity (hatchery 7.8%, pond 13.0%, and wild 35.1%) were significantly different
among groups. Wild fish had a higher probability of recapture upstream of their original
section than did hatchery or pond reared fish. Pond rearing was superior to conventional
hatchery rearing for subsequent stocking of 1 + grayling in running water. Initially
different mean condition factors were similar in all groups at recapture, suggesting
adaptation of the artificially reared fish that remained in the river sections surveyed.
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