Comparative life-history characteristics of native and hatchery-reared brown trout, Salmo trutta L., in a sub-Alpine reservoir

• Published in: Fisheries management and ecology Vol. 6; no. 1; pp. 47 - 61
• Main Authors: Hesthagen, T., Flòystad, L., Hegge, O., Staurnes, M., Skurdal, J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science, Ltd 01.02.1999
• Subjects: brown trout; hatchery-reared; life-history; reservoir; Salmo trutta; stocking; Norway, Vinstervatna Reservoir
• ISSN: 0969-997X; 1365-2400
• DOI: 10.1046/j.1365-2400.1999.00138.x

Wild and non‐native hatchery‐reared brown trout, Salmo trutta L., released when 2 summers old, were caught in the littoral habitat of Vinstervatna Reservoir, southern Norway. Hatchery‐reared brown trout grew more slowly and had a smaller asymptotic length (293 ± 71 mm CL) than native fish (391 ± 56 mm CL). Hatchery‐reared brown trout also exhibited significantly shorter life spans than native fish. This category consisted mainly of individuals aged 2+ and 3+ years, and only 1.5% of the specimens were aged ≥5 years. The ages of the native fish in the sample were between 2 and 8 years, and the most abundant age groups of trout were 4+ and 5+ years. It is suggested that the differences in life‐history characteristics are related to adaptations by the native trout to the local environmental conditions. In this reservoir, which has a limited food supply as a result of water level fluctuations and a high level of inter‐ and intraspecific competition, environmental effects might be significant.