Environmental Futures Research Institute, Griffith University, Brisbane, QLD, 4111, Australia.
National Institute of Standards and Technology, Hollings Marine Laboratory, Charleston, SC, 29412, USA.
Sci Rep. 2020 Feb 19;10(1):2954. doi: 10.1038/s41598-020-58933-4.
The blubber steroid hormone profiles of 52 female humpback whales migrating along the east coast of Australia were investigated for seasonal endocrine changes associated with reproduction. Individuals were randomly sampled during two stages of the annual migration: before reaching the breeding grounds (northward migration; June/July), and after departing from the breeding grounds (southward migration; September/October). Assignment of reproductive status of the sampled individuals was based on season, single-hormone ranks and multi-variate analysis of the hormonal profiles. High concentrations of progesterone (>19 ng/g, wet weight), recognised as an indicator of pregnancy in this species, were only detected in one sample. However, the androgens, testosterone and androstenedione were measured in unusually high concentrations (1.6-12 and 7.8-40 ng/g wet weight, respectively) in 36% of the females approaching the breeding grounds. The absence of a strong accompanying progesterone signal in these animals raises the possibility of progesterone withdrawal prior to parturition. As seen with other cetacean species, testosterone and androstenedione could be markers of near-term pregnancy in humpback whales. Confirmation of these androgens as alternate biomarkers of near-term pregnancy would carry implications for improved monitoring of the annual fecundity of humpback whales via non-lethal and minimally invasive methods.
本研究调查了 52 头沿澳大利亚东海岸洄游的雌性座头鲸的鲸脂类固醇激素谱，以研究与繁殖相关的季节性内分泌变化。在每年洄游的两个阶段随机采集个体样本：到达繁殖地之前（北移；6/7 月）和离开繁殖地之后（南移；9/10 月）。采样个体的生殖状态分配基于季节、单激素等级和激素谱的多变量分析。仅在一个样本中检测到高浓度的孕激素（>19ng/g，湿重），这在该物种中被认为是怀孕的指标。然而，在接近繁殖地的 36%的雌性动物中，雄激素睾酮和雄烯二酮的浓度异常高（分别为 1.6-12 和 7.8-40ng/g 湿重）。这些动物中没有强烈的伴随孕激素信号表明在分娩前可能出现孕激素撤退。与其他鲸类物种一样，睾酮和雄烯二酮可能是座头鲸近分娩期怀孕的标志物。如果这些雄激素被确认为近分娩期怀孕的替代生物标志物，那么通过非致死性和微创方法监测座头鲸每年的繁殖能力将具有重要意义。
