Beluga whales (Delphinapterus leucas) from Cook Inlet (CI), Alaska, are listed as “endangered” because of dramatic declines in abundance, with no indications of population recovery. Serum samples from this population are exceedingly rare. Longitudinal samples from aquarium (AQ) belugas can potentially provide health assessment reference ranges for free-ranging beluga, including reproductive and metabolic hormones. We analysed serum hormone concentrations from CI (n = 6, three females and three males) and Bristol Bay (Alaska; BB; n = 5, four males and one female), alongside AQ (n = 3, two females and one male) belugas, to conduct physiological comparisons of reproductive hormones (progesterone, testosterone and total oestrogens) and metabolic hormones (total thyroxine, triiodothyronine and cortisol) in beluga serum. Oestrogen and progesterone profiles from January through May from two AQ female beluga were typical of non-pregnant, cycling females. CI and BB sex steroid concentrations were within AQ hormone ranges, with the exception of elevated progesterone concentrations in four potentially pregnant females. Both CI and BB belugas had elevated metabolic hormones, which may indicate greater metabolic effort required in the wild environment or capture response. Because sample collection from CI belugas is rare, analysis of even the few samples that we analysed may contribute to the conservation of the small and declining population of genetically distinct CI beluga whales. It is important that each sample collected from free-range CI belugas provides the maximum biological information possible. Continued comparison of hormones in AQ and free-ranging beluga will enhance the interpretation of health data in both groups.

阿拉斯加库克湾 (CI) 的白鲸 ( Delphinapterus leucas ) 因数量急剧下降而被列为“濒危”，没有迹象表明种群数量恢复。该人群的血清样本极为罕见。来自水族馆 (AQ) 白鲸的纵向样本可能为自由放养的白鲸提供健康评估参考范围，包括生殖和代谢激素。我们分析了来自 CI（n  = 6，三名女性和三名男性）和布里斯托尔湾（阿拉斯加；BB；  n  = 5，四名男性和一名女性）以及 AQ（n = 3，两雌一雄）白鲸，对白鲸血清中的生殖激素（黄体酮、睾酮和总雌激素）和代谢激素（总甲状腺素、三碘甲状腺原氨酸和皮质醇）进行生理比较。从 1 月到 5 月，两只 AQ 雌性白鲸的雌激素和孕激素分布是未怀孕的骑自行车女性的典型特征。CI 和 BB 性类固醇浓度在 AQ 激素范围内，但四名可能怀孕的女性中黄体酮浓度升高除外。CI 和 BB 白鲸的代谢激素都升高了，这可能表明在野外环境中需要更大的代谢努力或捕获反应。因为从 CI belugas 采集的样本很少，即使是我们分析的少数样本的分析也可能有助于保护遗传上不同的CI白鲸的小数量且正在下降的种群。重要的是，从自由放养的 CI 白鲸中收集的每个样本都可以提供尽可能多的生物信息。继续比较 AQ 和自由放养白鲸中的激素将增强对两组健康数据的解释。