Beluga whales (Delphinapterus leucas) occur broadly throughout the polar and subpolar regions of the Northern Hemisphere, and as a whole, the species is of low conservation concern. However, some populations, including Alaska’s Cook Inlet beluga whales (CIBW), are in decline for reasons that remain poorly understood. Currently, information on population-specific reproductive parameters of CIBW is non-existent. To address this data gap, we examined long-term photo-identification data of CIBW for insight into the reproductive natural history of this endangered subarctic population. Data are from 438 photo-ID surveys conducted 2005–2017 and over 400 identified individuals, augmented with data from strandings, biopsies, and tagging. During the April–October ice-free field season, we observed neonates July–October but never April-June. We photo-documented three suspected births during July–September. Neonates were present in 30% of groups and encountered and comprised 2% of all belugas observed. Over the course of the 13-year study, the number of calves seen with an individual mother ranged from 1 to 5, with inter-birth intervals ranging from 2 to 13 years. This corresponds to rates of 0.08–0.38 calves per year per mother. Known-aged mothers ranged in age from 13 to 31 years. Skin color was not a reliable indicator of sexual maturity. Calves photographed alongside their mothers were estimated to be 1–8 years old, although most were 1–4 years old. Some mothers (6%) were accompanied by a neonate and an older calf. These summaries of observational data provide critical insight into CIBW reproductive natural history that will inform future population modeling and management decision-making.

中文翻译：

---

濒临灭绝的库克湾白鲸的繁殖自然史：来自长期照片识别研究的见解

白鲸（Delphinapterus leucas）广泛分布于北半球的极地和次极地地区，总体而言，该物种的保护关注度较低。然而，包括阿拉斯加库克湾白鲸 (CIBW) 在内的一些种群数量正在下降，原因尚不清楚。目前，关于 CIBW 的特定人群繁殖参数的信息不存在。为了解决这一数据差距，我们检查了 CIBW 的长期照片识别数据，以深入了解这个濒临灭绝的亚北极种群的繁殖自然史。数据来自 2005 年至 2017 年进行的 438 次带照片身份证调查和超过 400 名已识别个人，并增加了搁浅、活检和标记数据。在 4 月至 10 月的无冰野外季节，我们观察了 7 月至 10 月的新生儿，但从未观察到 4 月至 6 月。我们用照片记录了 7 月至 9 月期间三名疑似出生的婴儿。新生儿出现在 30% 的群体中，并在观察到的所有白鲸中占 2%。在为期 13 年的研究过程中，与一位母亲一起看到的小牛数量从 1 到 5 头不等，生育间隔从 2 年到 13 年不等。这对应于每位母亲每年 0.08-0.38 头小牛的比率。已知年龄的母亲年龄从 13 岁到 31 岁不等。肤色不是性成熟的可靠指标。与它们的母亲一起拍照的小牛估计是 1-8 岁，尽管大多数是 1-4 岁。一些母亲 (6%) 伴随着新生儿和年长的小牛。