Greater Dispersal of Wild Compared with Hatchery-Reared Juvenile Atlantic Salmon Released in Streams

• Published in: Journal of the Fisheries Research Board of Canada
• Main Author: Symons, Philip E. K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1969
• Subjects: General Medicine; Atlantic salmon; Salmo salar
• Online Access: http://dx.doi.org/10.1139/f69-170; http://www.nrcresearchpress.com/doi/pdf/10.1139/f69-170

When wild juvenile (parr) Atlantic salmon (Salmo salar L.) caught by electrofishing, and an equal number of hatchery-reared parr, matched for size with the wild ones, were released at three sites in unfamiliar streams containing resident parr, more hatchery-reared than wild parr could be observed by skin-diving in the areas 1 and 2 weeks later.Observed mortalities of wild parr were not sufficiently higher than those of hatchery parr to explain this result. Nor could a higher proportion of wild parr be found hiding compared with hatchery parr when one release site was electrofished a week after the release. Wild parr were found in greater numbers at points farther from one of the release sites than were hatchery-reared parr, and also more wild fish passed through a salmon counting fence approximately 100 m from a fourth release site than did hatchery-reared parr.This greater dispersal of wild parr from the release site compared with hatchery parr has important consequences to estimates of comparative survival between the two stocks.