Wild Atlantic salmon parr (N = 320; fork length = 6.1–10.4 cm; weight = 1.9–12 g) were collected on 16 June 2013, using a Smith-Root LR-24 backpack electrofisher from the Cains River (N46°25′59. 5; W066°01′29. 1—N46°26′05. 0; W066°01′10. 8 ± 15 m), a tributary of the Southwest Miramichi River. Fish were transported to the Harold Crabtree Aquatic Facility at Mount Allison University, NB, Canada and placed in a 750 L (circular fiberglass) recirculation holding tank at 15.00 ± 0.03°C. Fish were fed a mixture of dehydrated krill and commercial pellet feed (Corey Nutrition Company) twice daily until satiation. Water temperature was maintained until parr were weaned to feed exclusively on pellets (~10 days). Fish were subsequently fed once daily to satiation and exposed to a fluctuating ‘acclimation regime’ with nighttime minimum and daytime maximum temperatures (Tmin and Tmax) of 16 and 21 ± 0.2°C, respectively (mean ± SD; 12 h warming: 12 h cooling) with a natural photoperiod (~16 h light:8 h dark). Water temperature was monitored using an iBCod temperature logger (±1°C, 15 min interval, Alpha Mach Inc.) and dissolved oxygen (DO) was measured daily (7.5–10 mg L−1; YSI Pro 20, Xylem Inc.).