High Water Temperature Influences on Foraging Responses and Thermal Deaths of Dolly Varden Salvelinus malma and White-spotted Charr S. leucomaenis in a Laboratory

Water temperature effects on foraging responses and thermal tolerances of two congeneric charrs, Dolly Varden Salvelinus malma and white-spotted charr S. leucomaenis, were examined in aquarium settings. Appetites decreased at ≥16°C for Dolly Varden and at ≥24°C for white-spotted charr. The lethal temperatures were ≥20°C for Dolly Varden and ≥26°C for white-spotted charr. The upper limits of preferred temperature ranges and the lethal temperatures for Dolly Varden were significantly lower than those of white-spotted charr. Temperature preference and thermal tolerance probably play a major role in the distribution of these two species.