Seasonal variation in the temperature preference of Arctic charr (Salvelinus alpinus)

(1)Seasonal variation in thermal preference of Arctic charr from a North Norwegian population (70°N) was studied in an electronic shuttlebox, which allowed the fish to control the water temperature by moving between two chambers. The fish were acclimated to 12 °C and a natural photoperiod before measurements. Fish were tested in autumn (September–October), winter (January–February), spring (April–May) and summer (June–August).(2)Arctic charr showed a stable preference temperature of 11.5–11.8 °C from spring to autumn and a drop in preference temperature to 8.7 °C in winter.(3)In summer, the preference temperature of the charr coincided with environmental temperatures in their native lake, whereas during the other seasons, the preference temperatures were higher.(4)Overall, there was a positive correlation between individual fish growth rate and preference temperature, suggesting that the seasonal variation in preference temperature may be connected to seasonal variation in food intake and feeding motivation.