Tempering versus Acclimation in the Planting of Speckled Trout

The acclimation of speckled trout, Salvelinus fontinalis (Mitchill), by keeping them in tanks at temperatures from 13° to 22° C. (55.4° to 71.6° F.) for a period of 12 hours raised the lethal temperature from 24° C. (75.2° F.) to 26° C. (78.8° F.). The lethal temperature was assumed to be that temperature at which 50 per cent of the fish die within a period of 14 hours (Hathawayˈs method). Tempering speckled trout by gradually raising the temperature over a period of 15 minutes to that of the experimental tanks had no effect on the lethal temperature.