Abstract: Lateolabrax maculatus reared at 22–23 ℃ were acclimated at a cooling rate of 1, 3 or 5 ℃/h to the critical temperature 4 ℃ before live transportation for 8 h without using water. In order to establish the optimal cooling rate for reducing liver damage and increasing the survival rate during the transportation of fish, the effect of cold acclimation on liver damage in Lateolabrax maculatus was evaluated by detecting caspase-3 activity and malondialdehyde (MDA) content in liver and proprotein convertase subtilisin kexin type 9 (PCSK-9), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activity in serum. The results showed that at 0 h of transportation all investigated biochemical parameters in three treatment groups were higher than in the control group. At 8 h of transportation, these five parameters were significantly lower in the 3 ℃/h cooling group than in two other treatment groups but higher than in the control group (P < 0.05). At 2 h, serum PCSK-9 activity was significantly lower in the 3 ℃/h cooling group than in the other treatment groups (P < 0.05). Liver MDA concentration and caspase-3 activity in Chinese sea bass after arousal were decreased compared to those at 8 h but were still high. In addition, serum PCSK-9 activity was increased and AST activity was increased more slowly or declined, indicating that the liver damage caused by precooling treatment could not be recovered in a short time during live transportation without using water. Therefore, Lateolabrax maculatus can be kept alive by low temperature-induced hibernation, and sea bass acclimated at 3 ℃/h cooling rate suffered less liver damage and showed a higher survival rate at 8 h of transportation. In conclusion, a cooling rate of 3 ℃/h is recommended for Lateolabrax maculatus to transported alive without using water.

Key words: Lateolabrax maculatus, low temperature hibernation, liver, apoptosis, simulated live transportation without