The effect of anchor-ice dams on the physical habitat and behavioural responses of Atlantic salmon Salmo salar parr in a small, steep stream was investigated. Anchor-ice dams formed periodically, leading to a dynamic winter environment as the study reach alternated between riffle and walk dominated habitat. Parr demonstrated large individual variation in habitat use, utilizing most of the wetted stream width, and were generally unaffected by diel changes in the mesohabitat composition. Furthermore, parr displayed high site fidelity in areas with low embedded substrata, and demonstrated few large movements between the three mesohabitat classes present: shallow riffle, walk and pool. Findings from this study question the importance of hydraulic variables such as water depth, flow velocity and dynamic ice formation as single habitat features for juvenile stream salmonids during winter and emphasize the importance of access to substratum cover.
No Supplementary Data
passive integrated technology;
Document Type: Regular Paper
Fisheries and Oceans Canada, Science Branch, P. O. Box 5667, St John’s, NL, A1C 5X1 Canada
Parks Canada, Terra Nova National Park, Glovertown, NL, A0G 2L0 Canada
Department of Hydraulic and Environmental Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
Publication date: 2008-09-01