Abstract:
With the continuous development of global aquaculture, fish transportation has become a crucial issue for the efficient growth of the industry. As a high-value aquatic species, the Pearl grouper (
Epinephelus fuscoguttatus ×
E. lanceolatus) often experiences severe stress during transportation due to factors such as environmental changes, high density, and prolonged transportation time, which leads to a decline in immune function and even mortality. Traditional aquaculture transportation relies on water to meet the physiological needs of fish, but the consumption of nutrients and oxygen in the water often becomes a bottleneck that limits long-duration transport. The dry preservation technology, as an innovative transportation method, significantly reduces the use of water, lowers transportation costs, and extends transportation time and distance. However, traditional live transportation technologies rely on chemical anesthesia and hypothermic dormancy, which have raised concerns regarding drug residues and extended durations. Therefore, the corona sleep technology, a green, safe, and efficient new physical induction method, has gradually become a research hotspot. Currently, research on the application of corona sleep technology in Pearl grouper mainly focuses on its combination with low-temperature water-based preservation techniques. However, studies on combining it with dry preservation techniques are not yet reported. This study takes the Pearl grouper as the experimental subject and uses pulsed direct current electric shocks to induce dormancy, aiming to explore the joint application of corona sleep technology and dry preservation techniques. Through single-factor experiments combined with response surface optimization, the optimal corona sleep parameters for Pearl grouper were determined: voltage 126 V, shock time 5s, shock temperature 18°C, frequency 30 Hz, current 1 A, and duty cycle 25%. Under these conditions, the corona treatment induced dormancy, and the dormant grouper survived for (15.92±0.34)h in dry preservation at 15°C. Under the optimal corona treatment conditions, the biochemical responses, oxidative stress indicators, and energy metabolism changes of the grouper during dry preservation were analyzed. The results showed that with the extension of preservation time, the levels of cortisol (COR) and glucose (GLU) in the serum significantly increased (
P<0.05). The COR level reached its maximum value at 14h, increasing by 50.39% compared to the control group. Blood glucose content significantly increased between 3 and 14h of dry preservation (
P<0.05), indicating that the fish maintained blood glucose levels through gluconeogenesis. The activity of lactate dehydrogenase (LDH) continued to increase, suggesting that corona-induced dormancy triggered severe physiological stress, leading to elevated stress indicators. In addition, the levels of glutathione S-transferase (GST) and heat shock protein 70 (HSP70) in the liver and brain tissues significantly increased (
P<0.05), helping to alleviate the oxidative damage caused by the corona treatment and suppress the production of lipid peroxidation product malondialdehyde (MDA) and reactive oxygen species (ROS) during the low-temperature dry preservation process. This indicates that the fish’s antioxidant system was effectively activated, reducing the damage caused by environmental stress. Glycogen in the liver significantly decreased between 3h and 14h, while lactate in the muscles gradually increased, which was consistent with the rise in lactate dehydrogenase (LDH) activity, suggesting enhanced anaerobic metabolism. As the dry preservation time increased, glycogen was depleted and lactate accumulated. After rehydration, lactate levels significantly decreased, indicating that the fish had resumed aerobic metabolism. This suggests that the corona-induced dormancy technology can regulate energy metabolism pathways and alleviate energy consumption under low-oxygen conditions. In conclusion, the corona-induced dormancy technology can effectively extend the survival time of pearl gentian grouper in a dry environment. Moreover, it alleviates stress damage during dry preservation by activating antioxidant defense mechanisms and energy metabolism pathways. This study provides a novel and eco-friendly technological solution for live transportation of pearl gentian grouper and other marine fish species, laying a theoretical foundation and practical guidance for the future development of aquaculture and transportation technologies.