Cooperative Institute for Marine Resources Studies, Oregon State University and National Oceanic and Atmospheric Administration Pacific Marine Environmental Laboratory, 2030 Southeast Marine Science Drive, Newport, Oregon 97365, USA.
Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, Fife, United Kingdom.
J Acoust Soc Am. 2020 Feb;147(2):961. doi: 10.1121/10.0000617.
Acoustically equipped deep-water mobile autonomous platforms can be used to survey for marine mammals over intermediate spatiotemporal scales. Direct comparisons to fixed recorders are necessary to evaluate these tools as passive acoustic monitoring platforms. One glider and two drifting deep-water floats were simultaneously deployed within a deep-water cabled hydrophone array to quantitatively assess their survey capabilities. The glider was able to follow a pre-defined track while float movement was somewhat unpredictable. Fin whale (Balaenoptera physalus) 20 Hz pulses were recorded by all hydrophones throughout the two-week deployment. Calls were identified using a template detector, which performed similarly across recorder types. The glider data contained up to 78% fewer detections per hour due to increased low-frequency flow noise present during glider descents. The glider performed comparably to the floats and fixed recorders at coarser temporal scales; hourly and daily presence of detections did not vary by recorder type. Flow noise was related to glider speed through water and dive state. Glider speeds through water of 25 cm/s or less are suggested to minimize flow noise and the importance of glider ballasting, detector characterization, and normalization by effort when interpreting glider-collected data and applying it to marine mammal density estimation are discussed.
配备声学设备的深水平台可用于在中等时空尺度上调查海洋哺乳动物。为了将这些工具评估为被动声学监测平台，有必要与固定记录器进行直接比较。一个滑翔机和两个漂流式深海浮标同时部署在深海有缆水听器阵列中，以定量评估它们的调查能力。滑翔机能够沿着预先定义的轨迹飞行，而浮标运动则有些不可预测。在两周的部署期间，所有水听器都记录了长须鲸（Balaenoptera physalus）20Hz 脉冲。使用模板检测器识别叫声，该检测器在记录器类型之间表现相似。由于滑翔机下降过程中存在更多的低频水流噪声，每小时的检测次数减少了 78%。滑翔机与浮标和固定记录器在较粗的时间尺度上性能相当；每小时和每天的检测存在情况不因记录器类型而异。水流噪声与滑翔机在水中的速度和潜水状态有关。建议将滑翔机在水中的速度控制在 25cm/s 或以下，以最大程度地减少水流噪声，并讨论了在解释滑翔机采集的数据和应用于海洋哺乳动物密度估计时，对滑翔机压载、检测器特性和工作量标准化的重要性。
