A paucity of information on the basic biology and ecology of Cook Inlet beluga whales Delphinapterus leucas remains a decade after the species was listed as endangered in 2008. The causes of its continued decline remain unclear. This lack of knowledge limits our understanding of, and ability to manage, potential threats impeding the recovery of this endangered population. Seasonal distribution and foraging ecology, particularly during winter, are currently among the most basic gaps in knowledge. Therefore, we conducted a year-round passive acoustic monitoring program from 2008−2013, monitoring 13 locations within the belugas’ critical habitat. We identified seasonal occurrence patterns across years at most locations. Detections were higher in the upper inlet during summer, peaking in known concentration areas. The occurrence of whales in the upper inlet when ice coverage peaked during winter was more prevalent than previously suggested. We documented seasonal differences in foraging habitat preference, with foraging behavior more prevalent during summer, particularly near upper inlet rivers, than during winter. Foraging peaks coincided with the presence of different anadromous fish runs from spring to fall. Low levels of feeding activity in winter suggest a lack of feeding aggregation areas, feeding in non-monitored offshore waters, or increased effort on benthic prey. These results represent a substantial contribution to our knowledge of Cook Inlet beluga seasonal distribution and foraging ecology, which will strengthen conservation and management strategies and thus more effectively promote recovery of this endangered population.

中文翻译：

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基于被动声学监测的库克湾白鲸季节分布及觅食发生

库克湾白鲸 Delphinapterus leucas 的基本生物学和生态学信息在该物种于 2008 年被列为濒危物种十年后仍然缺乏。其持续下降的原因尚不清楚。这种知识的缺乏限制了我们对阻碍这一濒危种群恢复的潜在威胁的理解和管理能力。季节性分布和觅食生态，特别是在冬季，是目前最基本的知识空白。因此，我们从 2008 年到 2013 年开展了一项全年被动声学监测计划，监测了白鲸重要栖息地内的 13 个地点。我们在大多数地点确定了跨年的季节性发生模式。夏季，上游入口处的检测量较高，在已知浓度区域达到峰值。当冬季冰层覆盖达到顶峰时，上入口处出现鲸鱼的情况比之前预测的更为普遍。我们记录了觅食栖息地偏好的季节性差异，夏季觅食行为比冬季更普遍，尤其是在上游入口河流附近。觅食高峰恰逢春季到秋季不同溯河鱼类的出现。冬季觅食活动水平低表明缺乏觅食聚集区，在不受监控的近海水域觅食，或对底栖猎物的努力增加。这些结果对我们对库克湾白鲸季节性分布和觅食生态的了解做出了重大贡献，这将加强保护和管理策略，从而更有效地促进这一濒危种群的恢复。