Range expansions and increases in the frequency of killer whale (Orcinus orca ) sightings have been documented in the eastern Canadian Arctic, presumably the result of climate change‐related sea‐ice declines. However, the effects of increased predator occurrence on this marine ecosystem remain largely unknown. We explore the consequences of climate change‐related range expansions by a top predator by estimating killer whale abundance and their possible consumptive effects on narwhal (Monodon monoceros ) in the Canadian Arctic. Individual killer whales can be identified using characteristics such as acquired scars and variation in the shape and size of their dorsal fins. Capture–mark–recapture analysis of 63 individually identifiable killer whales photographed between 2009 and 2018 suggests a population size of 163 ± 27. This number of killer whales could consume >1,000 narwhal during their seasonal residency in Arctic waters. The effects of such mortality at the ecosystem level are uncertain, but trophic cascades caused by top predators, including killer whales, have been documented elsewhere. These findings illustrate the magnitude of ecosystem‐level modifications that can occur with climate change‐related shifts in predator distributions.

中文翻译：

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北极虎鲸的数量丰富，并预测了其在北极的消费。

在加拿大东部北极地区，据记录有范围扩大和目睹虎鲸（Orcinus orca）出现的频率增加，这大概是气候变化引起的海冰下降的结果。但是，捕食者增加对这一海洋生态系统的影响仍然未知。我们通过估计虎鲸丰和独角鲸的可能消费的影响通过探索一种捕食气候变化有关的范围扩张的后果（斑节对虾麒麟）在加拿大北极地区。可以使用诸如获得的疤痕以及其背鳍的形状和大小的变化等特征来识别各个虎鲸。对2009年至2018年之间拍摄的63条可单独识别的虎鲸的捕获，标记和重新捕获分析表明，其种群规模为163±27。在北极水域的季节性居留期间，这种虎鲸的消费量可能超过1,000头鲸。这种死亡率在生态系统水平上的影响尚不确定，但其他地方也记录了由顶级掠食者（包括虎鲸）引起的营养级联反应。这些发现说明了与气候变化相关的捕食者分布变化可能引起的生态系统级变化的规模。