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

Abstract

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.

Effect of supplementary stocking of juvenile brown trout, Salmo trutta, on yield in a Norwegian mountain reservoir

“…The proportion of stocked fish was higher among younger fish (age 1+ to 3+) than catchable size fish (age 4+ to 10+). A similar result was found in brown trout from another regulated lake in the same watershed (Hesthagen et al. 1999).…”

“…The proportion of stocked fish was higher among younger fish (age 1+ to 3+) than catchable size fish (age 4+ to 10+). A similar result was found in brown trout from another regulated lake in the same watershed (Hesthagen et al 1999). If stocked fish are unlikely to reach catchable size but constitute a relatively large fraction of younger fish, they may negatively affect growth and survival of young native conspecifics.…”

Disentangling stocking introgression and natural migration in brown trout: survival success and recruitment failure in populations with semi‐supportive breeding

“…Trout stocked in PAL are reared apart from the lake and released directly into the lake, thus lacking olfactory cues from their relative’s native tributary. O’Grady (1984) and Hesthagen et al. (1999) have previously reported that trout released directly into a lake may have reduced spawning runs into rivers.…”

Age and growth properties of brown trout (Salmo trutta L.) living in Kan Stream, upper Çoruh River, Turkey

“…Biological aspects such as growth, growth curve, reproduction, first maturity, fecundity, habitat use, sex ratio, and feeding characteristics in resident and sea trout have been studied in streams and lakes in Europe (Jonsson and Sandlund, 1979;Lobon-Cervia et al, 1986;Jonsson, 1989;Haugen and Rygg, 1996;Hesthagen et al, 1999;Nicola and Almodovar, 2002;Hesthagen et al, 2004), in North America (Mcfadden and Cooper, 1962;Beard and Carline, 1991) and in New Zealand (Allen, 1951).…”