Abstract-
Off Northern Chile, baleen whales use the area around Isla Chañaral as a feeding ground where they forage on euphausiids. Isla Chañaral 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 Chañaral 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 Chañaral. 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 Chañaral. The unique oceanographic features of Isla Chañaral and the Humboldt Archipelago that contribute to high concentrations of Endangered baleen whales and their prey justify the extension of the Isla Chañaral 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，须鲸利用查纳拉尔岛周围的地区作为觅食地，在那里觅食胡法鱼。查纳拉尔岛是洪堡洋流系统（HCS）内生产力很高的洪堡群岛（南纬28°S-29°）的一部分。在这项研究中，我们试图利用鲸鱼的系统和机会性视觉观测数据以及来自声学浮游动物和鱼类剖面仪（AZFP）的浮游动物系统声学后向散射数据，了解查纳拉尔岛周围长须鲸和蓝鲸及其猎物的亚中尺度空间分布；并利用遥感海洋学数据研究更广泛的洪堡群岛地区的海洋动力学。2018年，我们在20天内共完成了512.6公里的调查工作，2019年在16天内完成了318.3公里的调查，收集了系统的鲸鱼观测和反向散射数据。2018年共发现42头长须鲸、0头蓝鲸和66头不明身份的鲸鱼，2019年发现7头长须鲸，3头蓝鲸和12头不明身份鲸鱼。观测到的反向散射和鲸鱼的空间分布与测深特征密切相关，即围绕查纳拉尔岛弯曲的海底峡谷。广义加性模型表明，长须鲸的存在与高水平的反向散射和与峡谷相似的浅层深度有关。
关键词
须鲸觅食区，浮游动物声学反向散射，海洋动力学，ASL，AZFP，IPS5, 浮游生物鱼类在线监测，鱼探仪，
