The upper critical thermal limits for alevins of Arctic charr from a Norwegian lake north of the Arctic circle

Mean values ±95% CL of the upper incipient (T IL ) and ultimate (T UL ) lethal temperatures, determined at five acclimation temperatures ( T A ), increased for T IL from 19.2 ± 0.4° C ( T A 0.5° C) to 21.0 ± 0.4° C ( T A 20° C), and for T UL from 22.6 ± 0.1° C ( T A 0.5° C) to 26.6 ± 0.4° C ( T A 20° C). Mean values were close to those obtained for Arctic charr alevins from Windermere (north‐west England). These comparative data for alevins, and previous data for 0+ year parr, indicate negligible geographical variation in the thermal limits of Arctic charr.