Abstract-
Off Northern Chile, baleen whales use the area around Isla Cha?aral as a feeding ground where they forage on euphausiids. Isla Cha?aral is part of the highly productive Humboldt Archipelago (～ 28°S-29°S) within the Humboldt Current System (HCS). In this study, we seek to understand the sub mesoscale spatial distribution of fin and blue whales and their prey around Isla Cha?aral using systematic and opportunistic visual sighting data of whales and systematic acoustic backscatter data of zooplankton from an Acoustic Zooplankton and Fish Profiler (AZFP); and to examine the oceanographic dynamics of the wider Humboldt Archipelago area with remote-sensing oceanographic data. We completed a total of 512.6 km of survey effort over 20 days in 2018 and 318.3 km over 16 days in 2019 collecting systematic whale sighting and backscatter data. A total of 42 fin whales, 0 blue whales and66unidentified whales weresighted in 2018, and 7 f in whales, 3 blue whales and 12 unidentified whales were sighted in 2019. Observed spatial distribution of backscatter and whales was strongly associated with a bathymetric feature, i.e., the submarine canyon that curves around Isla Cha?aral. Generalized Additive Models showed that fin whale presence was associated with high levels of backscatter and shallow depths similar to those of the canyon. We found that long-term average geostrophic currents form a recirculation system between 28°S and 31°S that frontiersin.org Frontiers in Marine Science 01 Buchan et al. 10.3389/fmars.2023.1208262 can transport nutrient-rich upwelled surface waters back towards the Humboldt Archipelago and contribute to high biological productivity in this area. However, in summer 2019 geostrophic flow occurred away from the coast and a warm low-productivity spring explained low backscatter and whale sightings around Isla Cha?aral. The unique oceanographic features of Isla Cha?aral and the Humboldt Archipelago that contribute to high concentrations of Endangered baleen whales and their prey justify the extension of the Isla Cha?aral Marine Reserve to include the canyon between the mainland and the island, and the implementation of a Multiple Use Marine Protected Area for the entire Humboldt Archipelago area that explicitly protects this critical feature.
摘要：
在智利北部海域，須鯨利用查納拉爾島周圍的地區作為覓食地，在那里覓食胡法魚。查納拉爾島是洪堡洋流系統（HCS）內生產力很高的洪堡群島（南緯28°S-29°）的一部分。在這項研究中，我們試圖利用鯨魚的系統和機會性視覺觀測數據以及來自聲學浮游動物和魚類剖面儀（AZFP）的浮游動物系統聲學后向散射數據，了解查納拉爾島周圍長須鯨和藍鯨及其獵物的亞中尺度空間分布；并利用遙感海洋學數據研究更廣泛的洪堡群島地區的海洋動力學。2018年，我們在20天內共完成了512.6公里的調查工作，2019年在16天內完成了318.3公里的調查，收集了系統的鯨魚觀測和反向散射數據。2018年共發現42頭長須鯨、0頭藍鯨和66頭不明身份的鯨魚，2019年發現7頭長須鯨，3頭藍鯨和12頭不明身份鯨魚。觀測到的反向散射和鯨魚的空間分布與測深特征密切相關，即圍繞查納拉爾島彎曲的海底峽谷。廣義加性模型表明，長須鯨的存在與高水平的反向散射和與峽谷相似的淺層深度有關。
關鍵詞
須鯨覓食區，浮游動物聲學反向散射，海洋動力學，ASL，AZFP，IPS5, 浮游生物魚類在線監測，魚探儀，
