HIGH WATER TEMPERATURE INFLUENCES ON FORAGING RESPONSES AND THERMAL DEATHS OF DOLLY-VARDEN SALVELINUS-MALMA AND WHITE-SPOTTED CHARR SALVELINUS-LEUCOMAENIS IN A LABORATORY

Water temperature effects on foraging responses and thermal tolerances of two congeneric charrs, Dolly Varden Salvelinus malma and white-spo tted charr S. leucomaenis, were examined in aquarium settings. Appetit es decreased at greater than or equal to 16 degrees C for Dolly Varden and at greater than or equal to 24 degrees C for white-spotted charr. The lethal temperatures were greater than or equal to 20 degrees C fo r Dolly Varden and greater than or equal to 26 degrees C for white-spo tted charr. The upper limits of preferred temperature ranges and tile lethal temperatures for Dolly Varden were significantly lower than tho se of white-spotted charr. Temperature preference and thermal toleranc e probably play a major role in the distribution of these two species.