Integrating Passive Acoustic Monitoring in long-term oceanographic observations of the Bering Strait

This project aims to establish a base program for year-round acoustic monitoring of marine mammals in Bering Strait. Instrumentation will be added onto an existing high resolution physical and biological mooring program (National Science Foundation-Arctic Observing Network (AON) and Russian American Long-term Census of the Arctic), also supported by annual survey data. The combination of these data sets will provide urgently required, base-line information on how species presence varies seasonally with changes in sea ice, currents, ocean water temperatures and freshwater flow. Building on opportunistic proof-of-concept deployments in the strait in the last 2 years, the proposed effort will also provide critical, consistent data on interannual variability. The research project will test cutting edge scientific hypotheses such as: how do oceanographic conditions dictate the residency of different marine mammal species? Are temperate species invading the Arctic? What is the correlation between ice cover and marine mammal sound production? The Bering Strait is the only oceanic connection between the Pacific and the Arctic oceans. It is through this narrow (~85 km) passageway that the entire population of Bering-Chukchi-Beaufort bowhead whales passes twice yearly and that herds of beluga whales access Arctic waters. It is thought to be year-round habitat for ice seals and walrus. The Bering Strait is also the path by which Pacific sub-Arctic marine species are invading the Arctic. As the Northwest Passage becomes a viable Pacific-Atlantic shipping route, every ship along this route will pass through Bering Strait. It is, therefore, the region where climate change and changing anthropogenic utilization may have sizeable impacts on local marine fauna, and where changing fluxes of marine mammals to the Arctic can be well observed. Passive acoustic monitoring is the only method currently available to identify year-round, and in all weather conditions, the presence of marine mammals and other physical (ice movement) or anthropogenic (ships, oil and gas seismic exploration) sounds.

本项目旨在构建一套针对白令海峡海域海洋哺乳动物的全年声学监测基础方案。本项目将在现有高分辨率物理与生物锚定观测项目（美国国家科学基金会-北极观测网（AON）及俄美北极长期普查项目）的基础上加装声学监测设备，同时辅以年度调查数据支撑。整合上述数据集后，将获取亟需的基线信息，用以解析海洋哺乳动物物种出现频次如何随海冰、海流、海水温度及淡水通量的季节变化而波动。基于过去两年在该海峡开展的机会性概念验证部署工作，本次拟实施的研究还将提供关键且一致的年际变率数据集。本研究项目将验证多项前沿科学假说，例如：海洋水文条件如何决定不同海洋哺乳动物物种的居留模式？温带物种是否正在入侵北极海域？海冰覆盖与海洋哺乳动物发声之间存在何种关联？白令海峡是太平洋与北冰洋之间唯一的海洋连通通道。每年有两次白令-楚科奇-博福特弓鲸的全种群通过这条仅约85千米宽的水道，白鲸群也借此进入北极海域。该海域被认为是冰海豹与海象的全年栖息场所。白令海峡同时也是太平洋亚北极海洋物种入侵北极的通道。随着西北航道成为可行的太平洋-大西洋航运通道，所有途经该航线的船舶都将经过白令海峡。因此，该区域既是气候变化与人类活动方式改变可能对本地海洋动物群产生显著影响的区域，也是能够清晰观测海洋哺乳动物向北极迁徙通量变化的理想区域。被动声学监测（Passive Acoustic Monitoring）是目前唯一可实现全年、全天气下识别海洋哺乳动物及其他物理声源（如海冰移动）与人为声源（如船舶、油气地震勘探）的监测手段。