School of Aquatic and Fishery Sciences, University of Washington, Box 355020, Seattle, WA, 98105, USA.
Polar Science Center, Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, WA, 98105, USA.
Glob Chang Biol. 2017 Jun;23(6):2206-2217. doi: 10.1111/gcb.13564. Epub 2016 Dec 21.
Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea ('Chukchi') and Eastern Beaufort Sea ('Beaufort') beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze-up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between 'early' (1993-2002) and 'late' (2004-2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze-up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze-up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr ) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how belugas may fare in the future.
迁徙通常受到季节性环境梯度的影响，而这些梯度正日益受到气候变化的影响。北极海冰的快速变化可能会影响到许多海洋物种的迁徙，这些物种的迁徙时间与季节性海冰覆盖时间相匹配。这一主题尚未在太平洋北极白鲸 (Delphinapterus leucas) 中进行研究，它们沿着与季节性海冰覆盖时间相匹配的母系维持的秋季迁徙路线，在阿拉斯加和俄罗斯周围的水域中进行。对于在东楚科奇海（楚科奇）和东波弗特海（波弗特）共存的白鲸种群，我们利用两个独立的种群数据来源（卫星遥测数据和被动声学），研究了自 20 世纪 90 年代以来秋季迁徙时间的变化与区域海冰冻结延迟之间的关系。我们比较了“早期”（1993-2002 年）和“晚期”（2004-2012 年）标记期之间的迁徙日期。在晚期标记期间，楚科奇白鲸从波弗特海和楚科奇海的迁徙明显延迟（取决于位置，延迟 2 至 >4 周）。空间分析还表明，楚科奇白鲸离开波弗特海觅食区的时间在晚期也被推迟。随着波弗特海、楚科奇海和白令海的海冰冻结时间推迟，楚科奇白鲸秋季迁徙时间明显延迟。相比之下，波弗特白鲸在两个时期之间没有改变迁徙时间，也没有迁徙时间与冻结时间相关，除了在白令海峡向南迁徙。2008 年至 2014 年的被动声学数据为楚科奇白鲸从波弗特海（4 天/年）延迟迁徙提供了独立和补充支持。在这里，我们报告了第一个在其快速变化的太平洋北极生态系统背景下研究白鲸迁徙的物候学研究，表明了灵活的响应，这可能使其得以持续存在，但也使预测白鲸在未来的表现变得更加复杂。
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