The critical thermal maximum ( CT max ) of bull trout ( Salvelinus confluentus ) alevin was measured after 3 weeks of acclimation to 4–21°C. CT max increased from 24.3 at 4°C to 26.7 at 9°C, plateaued between 9 and 12°C (26.9°C), and declined to 25.9°C at 15°C. Acclimation mortality increased above 12°C, reaching 53.7% at 15°C, and no fish survived at 18–21°C. Condition factor declined at ≥12°C. Results indicate bull trout ale...

Maintaining natural thermal regimes in montane stream networks is critical for many species, but as climate warms, thermal regimes will undoubtedly change. Mitigating impacts of changing thermal regimes on freshwater biodiversity requires knowledge of which elements of the thermal regime are limiting factors for aquatic biota. We used full-year stream temperature records sampled across a broad latitudinal gradient to describe...

The upper thermal tolerance of brook trout Salvelinus fontinalis was estimated using critical thermal maxima (CT max ) experiments on fish acclimated to temperatures that span the species' thermal range (5–25°C). The CT max increased with acclimation temperature but plateaued in fish acclimated to 20, 23 and 25°C. Plasma lactate was highest, and the hepato‐somatic index ( I H ) was lowest at 23 and 25°C, which suggests additio...