Shark predation and tooth wear in a population of northeastern Pacific killer whales
Shark predation and tooth wear in a population of northeastern Pacific killer whales
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DOI：
10.3354/ab00307
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发表时间：
2011-01-01
期刊：
影响因子：
1.4
通讯作者：
Withler, Ruth E.
中科院分区：
文献类型：
--
作者：
Ford, John K. B.;Ellis, Graeme M.;Withler, Ruth E.
世界性的虎鲸 Orcinus orca 在其全球范围内以多种猎物类型为食，但至少在某些地区，基因独特且生态特殊的虎鲸谱系共存。在东北太平洋的沿海水域，有两种这样的谱系得到了很好的描述：所谓的“居民”捕食硬骨鱼，特别是鲑科鱼，而另一种（“瞬态”）则捕食海洋哺乳动物。从化学示踪剂看来，该地区的第三个谱系（“近海”）在生态上与居民和暂住者不同，但其饮食却鲜为人知。在这里，我们描述了两次与近海虎鲸的遭遇，期间观察到了多次涉及鲨鱼的捕食事件。通过对从这些捕食事件中收集的组织样本进行 DNA 分析，我们确定了猎物物种为太平洋睡鲨 Somniosus pacificus，并确定在 2 次遭遇中至少有 16 条个体被吃掉。这是根据野外觅食观测首次确认的近海虎鲸猎物物种，也是 Orcinus 猎物中任何睡眠物种的首次记录。我们还定量地表明，近海的顶齿磨损远大于常住和短暂停留的虎鲸，并提出这种磨损至少部分是由于鲨鱼皮肤中嵌入的真皮小齿的磨损造成的。需要进一步的研究来确定近海虎鲸在生态上是否与常住和短暂的虎鲸一样专业，以及鲨鱼是否在它们的饮食中发挥主导作用。
The cosmopolitan killer whale Orcinus orca feeds on a wide variety of prey types over its global range, but in at least some regions, genetically distinct and ecologically specialised lineages of killer whales coexist sympatrically. In coastal waters of the northeastern Pacific, 2 such lineages have been well described: the so-called 'residents' prey on teleost fish, especially salmonids and the other ('transients') on marine mammals. A third lineage in this region ('offshores') appears from chemical tracers to be ecologically distinct from residents and transients, but its diet is very poorly known. Here we describe 2 encounters with offshore killer whales during which multiple predation events involving sharks were observed. Using DNA analysis of tissue samples collected from these predation events, we identified the prey species as Pacific sleeper shark Somniosus pacificus and determined that a minimum of 16 individuals were consumed over the 2 encounters. This represents the first confirmed prey species of offshore killer whales based on field observations of foraging and the first record of any Somniosus species in the prey of Orcinus. We also show quantitatively that apical tooth wear is far greater in offshores than in resident and transient killer whales, and propose that such wear is at least in part due to abrasion from dermal denticles embedded in shark skin. Further studies are needed to determine whether offshore killer whales are as specialised ecologically as resident and transient killer whales, and whether sharks play a dominant role in their diet.