Fernandez Ajó A, Pirotta E, Bierlich K C, Hildebrand L, Bird C N, Hunt K E, Buck C L, New L, Dillon D, Torres L G
Geospatial Ecology of Marine Megafauna Lab, Marine Mammal Institute, Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Newport 97365, OR, USA.
Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, UK.
R Soc Open Sci. 2023 Jul 19;10(7):230452. doi: 10.1098/rsos.230452. eCollection 2023 Jul.
Knowledge of baleen whales' reproductive physiology is limited and requires long-term individual-based studies and innovative tools. We used 6 years of individual-level data on the Pacific Coast Feeding Group gray whales to evaluate the utility of faecal progesterone immunoassays and drone-based photogrammetry for pregnancy diagnosis. We explored the variability in faecal progesterone metabolites and body morphology relative to observed reproductive status and estimated the pregnancy probability for mature females of unknown reproductive status using normal mixture models. Individual females had higher faecal progesterone concentrations when pregnant than when presumed non-pregnant. Yet, at the population level, high overlap and variability in progesterone metabolite concentrations occurred between pregnant and non-pregnant groups, limiting this metric for accurate pregnancy diagnosis in gray whales. Alternatively, body width at 50% of the total body length (W50) correctly discriminated pregnant from non-pregnant females at individual and population levels, with high accuracy. Application of the model using W50 metric to mature females of unknown pregnancy status identified eight additional pregnancies with high confidence. Our findings highlight the utility of drone-based photogrammetry to non-invasively diagnose pregnancy in this group of gray whales, and the potential for improved data on reproductive rates for population management of baleen whales generally.
须鲸生殖生理学方面的知识有限，需要开展长期的基于个体的研究以及运用创新工具。我们利用了6年太平洋海岸觅食群灰鲸个体层面的数据，来评估粪便孕酮免疫测定法和基于无人机的摄影测量法用于妊娠诊断的效用。我们探究了粪便孕酮代谢物和身体形态相对于观察到的生殖状态的变异性，并使用正态混合模型估计了生殖状态未知的成年雌性的妊娠概率。怀孕的个体雌性粪便孕酮浓度高于推测未怀孕时的浓度。然而，在种群层面，怀孕组和未怀孕组之间孕酮代谢物浓度存在高度重叠和变异性，限制了这一指标用于准确诊断灰鲸妊娠。相比之下，在个体和种群层面，全长50%处的身体宽度（W50）能够准确地区分怀孕和未怀孕的雌性。使用W50指标模型对妊娠状态未知的成年雌性进行评估，高置信度地识别出另外8例妊娠。我们的研究结果凸显了基于无人机的摄影测量法在无创诊断这组灰鲸妊娠方面的效用，以及在总体上改善须鲸种群管理生殖率数据的潜力。
