Mortality is a demographic metric crucial for understanding the dynamics of endangered populations such as Cook Inlet beluga whales (CIBWs, Delphinapterus leucas), but patterns of mortality are currently not well understood for CIBWs, making decisions about recovery actions challenging. We combined long‐term photo‐ID data from approximately 420 individual belugas identified during the period 2005–2017 with stranding data from 95 dead belugas to identify patterns of mortality with respect to age, sex, geographic range, cause of death, and to estimate minimum mortality rates. Reported mortality was greatest for adults of reproductive age, followed by calves, with fewer subadults and no adults older than 49 years in the stranding data set despite lifespans of 70+ years reported in other beluga populations. Dead females and males were evenly represented. Live stranding was the predominant assigned cause of death but represented only ~33% of deaths of known cause. Causal factors for the majority of deaths and live strandings are unknown. Annual mortality estimated from reported carcasses relative to total population size averaged 2.2%. Our analysis advances our current understanding of mortality patterns in CIBWs but linking a greater proportion of carcasses to photo‐ID individuals would further improve our understanding; we conclude with recommendations for achieving this.

中文翻译：

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濒临灭绝的库克入口白鲸的死亡率模式：长期照片识别研究与搁浅记录相结合的见解

死亡率是一种人口统计指标，对于了解濒临灭绝的种群（如库克湾白鲸（CIBW，Delphinapterus leucas））的动态至关重要），但目前对于CIBW尚不十分了解死亡率的模式，这使得恢复行动的决策具有挑战性。我们将2005-2017年期间识别出的大约420个个体白鹭的长期photo-ID数据与95个死白鹭的搁浅数据相结合，以识别关于年龄，性别，地理范围，死亡原因的死亡率模式，并进行估计最低死亡率。尽管在其他白鲸种群中报告的寿命超过70岁，但在搁浅数据集中，报告的死亡率对育龄成年人最高，其次是小牛，亚成年较少，且没有49岁以上的成年人。死去的雌性和雄性被平均分配。搁浅是主要的死亡原因，但仅占已知原因死亡的33％。造成大多数死亡和生活搁浅的原因尚不清楚。根据报告的car体估计的年死亡率相对于总人口平均为2.2％。我们的分析提高了我们对CIBWs死亡率模式的当前理解，但是将更大比例的屠体与有照片ID的个体联系起来将进一步改善我们的理解。最后，我们提出了实现此目标的建议。