The dynamic response of HPI axis to two different transport modes in Acipenser baerii, Acipenser schrenckii and its hybrids (A. baerii x A. schrenckii)

The transport of live fish is an inevitable step in commercial production. This process often leads to a stress in fish, so it is crucial to find a suitable mode to transport fish. This study was conducted to study the effect of waterless and water transport modes on the transport stress of fish by ELISA kits and qPCR. In this study, The levels of hormones (cortisol, EPI, ACTH and CRH) and genes (GR , HSP90 and HSP70) expression related to the HPI axis were investigated in three kinds of sturgeons after live transport within water and waterless modes. Stress response in scleractinian fish is mainly regulated by the hypothalamic-pituitary-interrenal axis (HPI axis), and it releases hormones such as corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and cortisol for the body to mobilize and distribute energy to maintain homeostasis. The present study revealed that transport mode is one of the most important factors affected the stress response of fish. The result showed that sturgeon fingerlings under waterless transport had a stronger stress response and higher mortality, so transport mode with water was more suitable for three sturgeon fingerlings. In contrast, the HPI axis-related hormones and genes of both commercial A. baerii and hybrid F1 did not vary strongly under the transport modes. Furthermore, species is another important factor which may significantly affect the stress response ability. The results of the study showed that the stress response was the strongest in fingerling A. schrenckii , while the stress response was weaker in both sizes of hybrid F1, suggesting that hybrid F1 has some hybrid advantage over purebred fish in terms of transport tolerance. This work will help to make more effective strategies for cold water fish under different transport ways.