Department of Biological Sciences Aalesund, Norwegian University of Science and Technology, NTNU in Aalesund P.O. box 1517, Aalesund N-6025, Norway; Innolipid AS, Tonningsgate 17, Aalesund N-6006, Norway.
Department of Biological Sciences Aalesund, Norwegian University of Science and Technology, NTNU in Aalesund P.O. box 1517, Aalesund N-6025, Norway.
J Steroid Biochem Mol Biol. 2024 Sep;242:106542. doi: 10.1016/j.jsbmb.2024.106542. Epub 2024 May 10.
The sustainability of commercial aquaculture production depends critically on prioritizing fish welfare management. Besides monitoring welfare parameters such as fish behaviour and water quality, fish stress level can also provide a reliable measure of the welfare status of farmed fish. Cortisol and 5 of its metabolites (5β-THF, cortisone, 5β-DHE, 5β-THE, β-cortolone) were previously identified by the authors as suitable stress biomarkers of farmed Atlantic salmon. Based on this knowledge, the present study aimed to investigate the time-related dynamics of these metabolites in plasma, skin mucus, bile and faeces over a 72 h- period. The objective was to determine the optimal sampling time for each matrix and to understand the clearance pathway of these metabolites following stress. An experiment was carried out using a total of 90 Atlantic salmon with an average weight of 438 (±132) g. The average sea temperature was 6.9 °C during the experimental period. A control group of 10 fish was first collected before the remaining 80 fish were submitted to a stress of netting and subsequent relocation into two separate cages. From each of these two stress groups, 10 fish were sampled at 1 h, 2 h, 4 h, 6 h and 12 h, 24 h, 48 h, 72 h after the stress event respectively. The concentrations of cortisol and its metabolites were measured at each of the sampling timepoint. The results demonstrated that plasma cortisol metabolites reached the highest concentration 4 h after stress and remained elevated despite the slight decrease for the remaining timepoints. The peak level was observed at 12 h post-stress in skin mucus and 24 h in bile and faeces. The findings suggest that these timepoints are the optimal for sampling Atlantic salmon post-smolt following stressful events in acute stress studies. Furthermore, the results reveal that analysing cortisol and its metabolites, both in free and conjugated forms, rather than free cortisol provides greater flexibility as their concentrations are less affected by sampling procedure. This study confirms the appropriateness of skin mucus and faeces as less-invasive sample matrices for fish stress evaluation and provides a basis for further developing low invasive tools for monitoring the welfare of farmed salmonid.
商业水产养殖生产的可持续性取决于优先考虑鱼类福利管理。除了监测鱼类行为和水质等福利参数外，鱼类应激水平还可以提供一种可靠的养殖鱼类福利状况的衡量标准。皮质醇及其 5 种代谢物（5β-THF、皮质酮、5β-DHE、5β-THE、β-皮质酮）之前已被作者鉴定为养殖大西洋鲑鱼的合适应激生物标志物。基于这一知识，本研究旨在调查这些代谢物在血浆、皮肤黏液、胆汁和粪便中 72 小时内的时间相关动态。目的是确定每种基质的最佳采样时间，并了解应激后这些代谢物的清除途径。使用平均体重为 438（±132）g 的 90 条大西洋鲑鱼进行了一项实验。在实验期间，平均海水温度为 6.9°C。首先采集了 10 条对照鱼，然后将其余 80 条鱼网捕并转移到两个单独的笼子中。从这两个应激组中，分别于应激事件后 1、2、4、6 和 12、24、48、72 小时采集 10 条鱼进行采样。在每个采样时间点测量皮质醇及其代谢物的浓度。结果表明，血浆皮质醇代谢物在应激后 4 小时达到最高浓度，尽管在其余时间点略有下降，但仍保持升高状态。在皮肤黏液中，应激后 12 小时达到峰值，在胆汁和粪便中，应激后 24 小时达到峰值。这些发现表明，在急性应激研究中，这些时间点是对处于变态后阶段的大西洋鲑鱼进行采样的最佳时间点。此外，研究结果表明，分析皮质醇及其代谢物，包括游离和结合形式，而不是游离皮质醇，提供了更大的灵活性，因为它们的浓度受采样程序的影响较小。本研究证实了皮肤黏液和粪便作为鱼类应激评估较少侵入性样本基质的适宜性，并为进一步开发用于监测养殖鲑鱼福利的低侵入性工具提供了基础。
