Cooperative Institute for Climate, Ocean and Ecosystem Studies, University of Washington, Seattle, WA, United States of America.
Marine Mammal Laboratory, Alaska Fisheries Science Center, NOAA, National Marine Fisheries Service, Seattle, WA, United States of America.
PLoS One. 2021 Nov 30;16(11):e0260485. doi: 10.1371/journal.pone.0260485. eCollection 2021.
Cook Inlet, Alaska, is home to an endangered and declining population of 279 belugas (Delphinapterus leucas). Recovery efforts highlight a paucity of basic ecological knowledge, impeding the correct assessment of threats and the development of recovery actions. In particular, information on diet and foraging habitat is very limited for this population. Passive acoustic monitoring has proven to be an efficient approach to monitor beluga distribution and seasonal occurrence. Identifying acoustic foraging behavior could help address the current gap in information on diet and foraging habitat. To address this conservation challenge, eight belugas from a comparative, healthy population in Bristol Bay, Alaska, were instrumented with a multi-sensor tag (DTAG), a satellite tag, and a stomach temperature transmitter in August 2014 and May 2016. DTAG deployments provided 129.6 hours of data including foraging and social behavioral states. A total of 68 echolocation click trains ending in terminal buzzes were identified during successful prey chasing and capture, as well as during social interactions. Of these, 37 click trains were successfully processed to measure inter-click intervals (ICI) and ICI trend in their buzzing section. Terminal buzzes with short ICI (minimum ICI <8.98 ms) and consistently decreasing ICI trend (ICI increment range <1.49 ms) were exclusively associated with feeding behavior. This dual metric was applied to acoustic data from one acoustic mooring within the Cook Inlet beluga critical habitat as an example of the application of detecting feeding in long-term passive acoustic monitoring data. This approach allowed description of the relationship between beluga presence, feeding occurrence, and the timing of spawning runs by different species of anadromous fish. Results reflected a clear preference for the Susitna River delta during eulachon (Thaleichthys pacificus), Chinook (Oncorhynchus tshawytscha), pink (Oncorhynchus gorbuscha), and coho (Oncorhynchus kisutch) salmon spawning run periods, with increased feeding occurrence at the peak of the Chinook and pink salmon runs.
库克湾是 279 头白鲸（Delphinapterus leucas）的家园，它们正处于濒危和衰退之中。恢复工作强调了基本生态知识的缺乏，阻碍了对威胁的正确评估和恢复行动的制定。特别是，关于这种物种的饮食和觅食栖息地的信息非常有限。事实证明，被动声学监测是监测白鲸分布和季节性出现的有效方法。识别声学觅食行为有助于解决当前有关饮食和觅食栖息地的信息差距。为了解决这一保护挑战，2014 年 8 月和 2016 年 5 月，在阿拉斯加布里斯托尔湾的一个比较健康的白鲸群体中，对 8 头白鲸进行了多传感器标签（DTAG）、卫星标签和胃温发射器的安装。DTAG 的部署提供了 129.6 小时的数据，包括觅食和社会行为状态。在成功追逐和捕捉猎物以及社交互动过程中，共识别到 68 次以终端嗡嗡声结束的回声定位点击列车。在这些点击列车中，有 37 次成功处理了点击间隔（ICI）的测量和嗡嗡声部分的 ICI 趋势。具有短 ICI（最小 ICI<8.98ms）和一致减小的 ICI 趋势（ICI 增量范围<I.49ms）的终端嗡嗡声专门与进食行为相关。该双重指标应用于库克湾白鲸关键栖息地内的一个声学系泊处的声学数据，作为在长期被动声学监测数据中检测进食的应用示例。该方法允许通过不同洄游鱼类物种描述白鲸存在、觅食发生和产卵洄游时间之间的关系。结果反映了在白令海鲑鱼（Thaleichthys pacificus）、奇努克鲑（Oncorhynchus tshawytscha）、粉鲑（Oncorhynchus gorbuscha）和银鲑（Oncorhynchus kisutch）产卵洄游期间，白鲸对白令河三角洲明显的偏好，在奇努克鲑和粉鲑洄游高峰期，觅食活动增加。
