Temperature preference of the Chesapeake logperch, Percina bimaculata

The impact of increased temperature on poikilotherms has been extensively studied for more than 75 years. Generally, the preferred temperature of most temperate fishes increases with an increase in acclimation temperature to the point where acclimation temperature equals preference temperature (i.e., the final preferred temperature). Temperature preference of the Chesapeake Logperch was consistently higher than the acclimation temperature for adults in freshwater. At the highest acclimation temperature (25°C), the fish in freshwater had a mean preferred temperature of 26.5°C. Two fish acclimated to 25°C swam into water with a temperature of 30°C and immediately lost equilibrium. Adult Chesapeake Logperch acclimated to 5 g/l salinity and 25°C had a preferred temperature of 24.7°C. Juveniles had a final preferred temperature of 26°C, when acclimated to 25°C. These results have several management implications. If Chesapeake Logperch, a species under active reintroduction programs, does not avoid lethal temperatures, then there will be increased mortality in habitats exposed to thermal effluents. Successful restoration may therefore require ensuring access to cooler refugia within river systems. More broadly, these findings challenge the assumption that behavioral thermoregulation consistently protects fishes from lethal stress, emphasizing the need to consider both preference and avoidance behavior when predicting species' responses to thermal variability, habitat alteration, and biological invasions.