Fig. 4. Maximum activities of (A,B) citrate synthase and (C,D) cytochrome c oxidase in liver of G. morhua after acclimation to 4°C and 10°C. Activities were measured at 10°C. The values in A and C are expressed relative to wet mass. For the calculation of activities in total liver (B,D) individual enzyme activities determined per g wet mass were multiplied by the hepatosomatic index thus yielding an activity value for all liver in 100 g fish. Values are means ± s.e.m. (N=5–6). The data were tested for outliers at the 95% significance level using Nalimov'stest (Noack, 1980). *Significant difference from the warm-acclimated control group within a population; *significant difference between populations at the same acclimation temperature.