Our understanding about how environmental and biological variables may influence circulating thyroid and adrenal hormones in free-ranging cetaceans is limited. As such, we used liquid chromatography–mass spectrometry to determine concentrations of circulating cortisol and thyroid hormones (THs; tT3, tT4) in 132 Yangtze finless porpoises (YFPs) located in Poyang Lake, (PL, n = 92) and Tian-E-Zhou Oxbow reserve (TZO, n = 40). For overall hormone comparisons, animals were partitioned by age [juvenile and adult (male and non-pregnant, non-lactating female)], sex, season (winter or spring) and geographical location. Geographically, during winter, circulating THs were significantly higher in the PL versus TZO population. Seasonally, within PL, THs were significantly higher in the winter versus spring season. Animals were further binned into groups as follows: juvenile male (JM) and juvenile female (JF), adult male (AM), non-pregnant adult female, pregnant female and non-pregnant lactating female. Intra-group comparisons between locations showed a significant increase in JM THs at PL. Significant increases in THs during winter compared to spring were detected between JM and JF groups. Mean comparisons of cortisol within and between locations for each group identified a significant increase for TZO AM versus TZO pregnant female and JM and JF. Seasonally, in PL, only JF has significantly higher cortisol in winter versus spring. Finally, we established reference values of THs and cortisol for YFPs in different geographical locations. These references are important baselines from which the effects of environmental and biological variables on THs and cortisol may be evaluated.

中文翻译：

---

野生和半天然长江江豚 (Neophocaena asiaeorientalis) 体内甲状腺激素和皮质醇的循环浓度

我们对环境和生物变量如何影响自由放养鲸类动物的循环甲状腺和肾上腺激素的理解有限。因此，我们使用液相色谱-质谱法测定了位于鄱阳湖 (PL, n  = 92) 和 Tian-E的 132 只长江江豚 (YFP) 中循环皮质醇和甲状腺激素 (THs; tT3, tT4) 的浓度-Zhou Oxbow 保护区 (TZO, n = 40)。对于整体激素比较，动物按年龄[少年和成年（男性和非怀孕，非哺乳期女性）]、性别、季节（冬季或春季）和地理位置进行划分。从地理上看，在冬季，PL 与 TZO 人群中的循环 TH 显着更高。季节性地，在 PL 内，冬季的 TH 明显高于春季。将动物进一步分组如下：幼年雄性 (JM) 和幼年雌性 (JF)、成年雄性 (AM)、未怀孕的成年雌性、怀孕的雌性和未怀孕的哺乳期雌性。地点之间的组内比较显示，PL 的 JM TH 显着增加。在 JM 和 JF 组之间检测到冬季与春季相比 TH 显着增加。每组位置内和位置之间皮质醇的平均比较发现 TZO AM 与 TZO 怀孕女性以及 JM 和 JF 显着增加。季节性地，在 PL 中，只有 JF 在冬季与春季相比具有显着更高的皮质醇。最后，我们为不同地理位置的 YFP 建立了 TH 和皮质醇的参考值。这些参考资料是重要的基线，可以评估环境和生物变量对 TH 和皮质醇的影响。