Shuttleworth Loraine, Ganswindt Andre, Hunt Kathleen E, Fernández Ajó Alejandro, Pieterse Estefan, Seakamela S Mduduzi, Schoeman Chantel, Vermeulen Els
Faculty of Natural and Agricultural Sciences, Mammal Research Institute University of Pretoria Pretoria South Africa.
Smithsonian-Mason School of Conservation Front Royal Virginia USA.
Ecol Evol. 2025 Jun 17;15(6):e71528. doi: 10.1002/ece3.71528. eCollection 2025 Jun.
Gestation length is a key reproductive parameter influencing fecundity, population growth rates, and the recovery potential of baleen whales. However, direct knowledge of the gestation length in these large mammals remains limited, primarily inferred from whaling and observational data. Over the past decade, southern right whales have experienced a decline in reproductive success, likely linked to climate-change-induced shifts in foraging conditions. Understanding the population-level consequences of these changes requires detailed longitudinal reproductive data. This study analyzes multiyear steroid hormone profiles in the baleen of adult female southern right whales stranded along the South African coast. Results show an extended hormonal pattern characterized by two peaks in progestogens between 20 and 25 months-suggesting putative pregnancies lasting substantially longer than previous estimates. Sharp estrogen peaks during periods of elevated progestogen phases may indicate hormonal regulation of myometrial contractions at birth. A positive correlation between progestogens and glucocorticoids suggests a role for glucocorticoids in pregnancy maintenance, while androgens provide limited insight into female reproduction in this species. These findings imply a longer-than-expected gestation period for southern right whales and potentially across the balaenid family. This has important implications for understanding the timing and location of conception, relevant for conservation management strategies. Multipopulation studies alongside individual sighting histories are recommended to refine our understanding of southern right whale reproduction further.
妊娠期长度是影响须鲸繁殖力、种群增长率和恢复潜力的关键生殖参数。然而，对于这些大型哺乳动物妊娠期长度的直接了解仍然有限，主要是根据捕鲸和观测数据推断得出。在过去十年中，南露脊鲸的繁殖成功率有所下降，这可能与气候变化导致的觅食条件变化有关。要了解这些变化对种群水平的影响，需要详细的纵向生殖数据。本研究分析了沿南非海岸搁浅的成年雌性南露脊鲸鲸须中多年的类固醇激素谱。结果显示出一种延长的激素模式，其特征是孕激素在20至25个月之间出现两个峰值，这表明假定的妊娠期比之前的估计长得多。在孕激素水平升高期间出现的雌激素峰值可能表明出生时子宫肌层收缩的激素调节。孕激素与糖皮质激素之间的正相关表明糖皮质激素在维持妊娠中发挥作用，而雄激素对该物种雌性繁殖的了解有限。这些发现意味着南露脊鲸以及可能整个露脊鲸科的妊娠期都比预期的要长。这对于理解受孕的时间和地点具有重要意义，与保护管理策略相关。建议开展多群体研究并结合个体目击历史，以进一步完善我们对南露脊鲸繁殖的理解。
