This paper describes the relationship between eastern North Pacific gray whale calf production and environmental conditions in the Pacific Arctic where they feed. The results show how interannual variation in sea ice cover in the Bering and Chukchi Seas along with broader indices of North Pacific climate, such as Pacific Decadal Oscillation (PDO) and North Pacific Index (NPI), are linked to variation in gray whale reproductive output. Estimates of gray whale calf production were derived from 23 consecutive years (1994–2016) of shore‐based visual surveys conducted off California during the northward migration. PDO and NPI in combination with ice cover in the Bering and Chukchi Seas during the early phase of gestation appear to be important in explaining the observed variability in calf production. Of the 2,285 time series linear models evaluated, the model of best‐fit included PDO(July), Ice(June), NPI(February), and explained 60% of the observed variability in calf production. After elimination of two data outliers in calf production estimates (2013 and 2014) a model including Ice(May), PDO(May), and NPI(July) explained 90% of the variability. We conclude that access to prey early in the gestation period is critical to reproductive success in this population and may be important for other capital breeding mammals.

中文翻译：

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影响北太平洋东部灰鲸犊牛生产的环境因素1994–2016

本文介绍了北太平洋东部灰鲸犊牛的产量与它们所取食的太平洋北极地区环境条件之间的关系。结果表明，白令海和楚科奇海海冰盖度的年际变化以及北太平洋气候的更广泛指数（如太平洋十进制涛动（PDO）和北太平洋指数（NPI））如何与灰鲸繁殖产量的变化相关联。灰鲸犊牛产量的估算值是从北向迁徙期间连续23年（1994-2016年）在加利福尼亚州外进行的基于海岸的视觉调查得出的。在妊娠早期，白令海和楚科奇海的PDO和NPI加上冰盖似乎对解释观察到的小牛生产的变化很重要。在评估的2285个时间序列线性模型中，最佳拟合模型包括PDO（7月），Ice（6月），NPI（2月），并解释了所观察到的小牛生产变化的60％。在剔除小牛产量估算值（2013年和2014年）中的两个数据异常值之后，一个模型（包括Ice（5月），PDO（5月）和NPI（7月））解释了90％的变异性。我们得出的结论是，在妊娠早期获取猎物对于该种群的繁殖成功至关重要，对其他主要繁殖哺乳动物可能也很重要。