Cooperative Institute for Marine and Atmospheric Studies, University of Miami, Miami, Florida, United States of America.
Department of Biology, University of Victoria, Victoria, British Columbia, Canada.
PLoS One. 2024 Sep 4;19(9):e0308461. doi: 10.1371/journal.pone.0308461. eCollection 2024.
The Ocean Networks Canada (ONC) cabled video-observatory at the Barkley Canyon Node (British Columbia, Canada) was recently the site of a Fish Acoustics and Attraction Experiment (FAAE), from May 21, 2022 to July 16, 2023, combining observations from High-Definition (HD) video, acoustic imaging sonar, and underwater sounds at a depth of 645 m, to examine the effects of light and bait on deep-sea fish and invertebrate behaviors. The unexpected presence of at least eight (six recurrent and two temporary) sub-adult male northern elephant seals (Mirounga angustirostris) was reported in 113 and 210 recordings out of 9737 HD and 2805 sonar videos at the site, respectively. Elephant seals were found at the site during seven distinct periods between June 22, 2022 and May 19, 2023. Ethograms provided insights into the seal's deep-sea resting and foraging strategies, including prey selection. We hypothesized that the ability of elephant seals to perform repeated visits to the same site over long periods (> 10 days) was due to the noise generated by the sonar, suggesting that they learned to use that anthropogenic source as an indicator of food location, also known as the "dinner bell" effect. One interpretation is that elephant seals are attracted to the FAAE site due to the availability of prey and use the infrastructure as a foraging and resting site, but then take advantage of fish disturbance caused by the camera lights to improve foraging success. Our video observations demonstrated that northern elephant seals primarily focused on actively swimming sablefish (Anoplopoma fimbria), ignoring stationary or drifting prey. Moreover, we found that elephant seals appear to produce (voluntary or involuntary) infrasonic sounds in a foraging context. This study highlights the utility of designing marine observatories with spatially and temporally cross-referenced data collection from instruments representing multiple modalities of observation.
加拿大海洋网络（ONC）在 Barkley 峡谷节点（加拿大不列颠哥伦比亚省）的有缆视频观测站最近成为鱼类声学和吸引力实验（FAAE）的所在地，该实验于 2022 年 5 月 21 日至 2023 年 7 月 16 日进行，结合了来自水深 645 米处的高清（HD）视频、声学成像声纳和水下声音的观测，以研究光和诱饵对深海鱼类和无脊椎动物行为的影响。在该地点的 9737 个 HD 视频和 2805 个声纳视频中，分别有 113 个和 210 个视频记录到至少 8 只（6 只重复出现，2 只临时出现）亚成年雄性北方象海豹（Mirounga angustirostris）的出现。海豹在 2022 年 6 月 22 日至 2023 年 5 月 19 日之间的七个不同时期在该地点被发现。行为谱提供了有关海豹深海休息和觅食策略的深入了解，包括猎物选择。我们假设，象海豹能够在很长时间（> 10 天）内重复访问同一个地点的能力是由于声纳产生的噪音，这表明它们学会利用这种人为来源作为食物位置的指示物，也称为“晚餐铃”效应。一种解释是，象海豹被 FAAE 站点的猎物吸引，并将基础设施用作觅食和休息场所，但随后利用相机灯光引起的鱼类干扰来提高觅食成功率。我们的视频观察表明，北方象海豹主要关注 actively swimming 的黑貂石斑鱼（Anoplopoma fimbria），忽略静止或漂流的猎物。此外，我们发现象海豹在觅食时似乎会发出（自愿或非自愿）次声。这项研究强调了设计海洋观测站的实用性，这些观测站使用来自代表多种观测模式的仪器进行空间和时间交叉参考数据收集。
