Jourdain Eve, Vongraven Dag, Bisther Anna, Karoliussen Richard
Norwegian Orca Survey, Andenes, Norway.
Norwegian Polar Institute, Tromsø, Norway.
PLoS One. 2017 Jun 30;12(6):e0180099. doi: 10.1371/journal.pone.0180099. eCollection 2017.
Killer whales (Orcinus orca) have been documented preying on either fish or marine mammals in several regions, suggesting that this odontocete species has the ability to specialize on different types of prey. Off Norway, killer whales have been shown to rely on the Atlantic herring (Clupea harengus) as a main prey resource. Infrequent observations have revealed seals as an additional component of their diet, yet the extent of predation on marine mammals has remained largely unknown. Here, we present the findings of 29 years of photographic and observational data on seal-feeding killer whale groups identified in Norwegian coastal waters. Four groups have been observed preying and feeding on seals over several years, taking both harbor (Phoca vitulina) and grey (Halichoerus grypus) seals. These stable groups are shown to adopt small group sizes, were typically observed in near-shore areas and were not encountered on herring wintering grounds. Behavioral and social traits adopted by these groups are similar to those of pinniped-feeding killer whales from other regions. The potential ecological reasons and the extent of such prey specializations are discussed.
虎鲸（逆戟鲸）在多个地区都有捕食鱼类或海洋哺乳动物的记录，这表明这种齿鲸有能力专门捕食不同类型的猎物。在挪威沿海，虎鲸已被证明主要以大西洋鲱鱼（Clupea harengus）为猎物资源。偶尔的观察发现海豹是它们饮食中的另一个组成部分，但对海洋哺乳动物的捕食程度在很大程度上仍不为人知。在此，我们展示了29年来在挪威沿海水域识别出的以海豹为食的虎鲸群体的照片和观测数据结果。多年来观察到有四个群体捕食海豹，包括港湾海豹（Phoca vitulina）和灰海豹（Halichoerus grypus）。这些稳定的群体规模较小，通常在近岸区域被观察到，在鲱鱼越冬地未被发现。这些群体所采用的行为和社会特征与其他地区以鳍足类动物为食的虎鲸相似。本文还讨论了这种猎物专业化的潜在生态原因及程度。
