The Effects of Transport Stress (Temperature and Vibration) on Blood Biochemical Parameters, Oxidative Stress, and Gill Histomorphology of Pearl Gentian Groupers

Abstract

The transport of living fish is an important part of the fish farming process. The transport usually causes fish stress. This study evaluated the effects of transport temperature and vibration frequency on water quality, blood biochemical parameters, gill histomorphology, oxidative stress, and meat quality of pearl gentian groupers after transport. First, 1-year-old groupers (450 ± 25 g) were transported in plastic bags for 48 h, including the following treatments: no shaking, transported at 15 °C, shaking at 70 rpm, transported at 15 °C (15 °C/70 rpm); shaking at 120 rpm, transported at 15 °C (15 °C/120 rpm); no shaking, transported at 25 °C; shaking at 70 rpm, transported at 25 °C (25 °C/70 rpm); and shaking at 120 rpm, transported at 25 °C (25 °C/120 rpm). Serum, liver, gill, and muscle samples were collected for testing at 0, 12, 24, 36, and 48 h of exposure. During the 48 h transport, total ammonia nitrogen (TAN), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-PX), and malondialdehyde (MDA) were significantly increased in the transport group compared to the control group. In the early stage of transportation, aspartate aminotransferase (AST), alanine aminotransferase (ALT), cortisol (COR), lactate dehydrogenase (LDH), and glucose (GLU) in the transportation groups were significantly higher than those in the control group, while the water quality pH and dissolved oxygen (DO) levels decreased significantly. Compared with untransported fish, the total free amino acid (TFAA) content increased by 40.27% and 31.74% in the 25 °C/70 rpm and 25 °C/120 rpm groups, respectively. In addition, the results of hematoxylin–eosin staining and scanning electron microscopy showed that the epithelial cells in the high-speed group were swollen, the gill lamella was severely curved, and a large amount of mucus was secreted. This study explores the basic information of transportation, which will help to select the conditions that are more suitable for the successful transportation of pearl gentian groupers.