FISHERIES RESEARCH INSTITUTE,MOA,TAIWAN

This study investigated the effects of low-temperature stress on the plasma biochemical parameters of longtooth grouper (Epinephelus bruneus), giant grouper (E. lanceolatus) and a hybrid grouper (E. bruneus × E. lanceolatus). In the low-temperature exposure experiment, the temperature was reduced by 0.8℃ per hour from 26℃ to 15℃. The fish plasma was sampled and analyzed at 26℃ (Sampling time 1, S1), 15℃ (S2), 24 hours after exposure to 15℃ (S3), recovery to 26℃ (S4) and 24 hours after recovery to 26℃ (S5), respectively. The results showed that the glucose (GLU) concentration of longtooth grouper was significantly increased at S3 and recovered to the control group level at S5. The GLU concentration of giant grouper at S2-S3 was significantly higher than that in the control group even at recovery to 26℃. The GLU concentration of hybrid grouper was significantly increased at S3 and also recovered to the control group level at S5. The plasma triglyceride (TRIG) and cholesterol (CHOL) concentrations of the three grouper species were all significantly increased during the low-temperature exposure period. The results indicated that the GLU, TRIG and CHOL concentrations of the three grouper species were obviously changed during the low-temperature exposure and recovery periods. Based on the changes in their plasma GLU concentrations, the physiological acclimation ability of the hybrid grouper was higher than that of the giant grouper during the cold stress period.