The Grey Seal (Halichoerus grypus) as a Predator of Harbour Porpoises (Phocoena phocoena)?
The Grey Seal (Halichoerus grypus) as a Predator of Harbour Porpoises (Phocoena phocoena)?
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DOI：
10.1578/am.38.4.2012.343
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发表时间：
2012-01-01
期刊：
影响因子：
1.2
通讯作者：
Degraer, Steven
中科院分区：
文献类型：
--
作者：
Haelters, Jan;Kerckhof, Francis;Degraer, Steven
2011年9月，两只港鼠海豚（Phocoena phocoena）在比利时被冲上岸，造成广泛的创伤性损伤。类似的病变，大部分皮肤和脂肪缺失，以前在比利时的港口鼠海豚身上没有记录，但最近在邻国的一些病例中观察到。我们将病变与可能的捕食者的嘴和牙齿结构进行了比较。搁浅的情况、尸检期间的观察结果以及海豹头骨调查的结果都表明，海豹（可能是灰海豹（Halichoerus grypus））是造成这两头港鼠海豚死亡的主要嫌疑人。虽然不能完全排除纯粹的攻击性行为，但捕食被认为最有可能是因为海港鼠海豚的皮肤和鲸脂组织的一部分丢失了。灰海豹是一种机会性捕食者，以各种鱼类和头足类动物为食，偶尔甚至以甲壳类动物和海鸟为食，但据我们所知，从未描述过对港湾鼠海豚或任何其他海洋哺乳动物的捕食。这一发现可能为最近滞留在北海南部海滩的其他一些残缺不全的港口鼠海豚的死因提供了新的线索，它提出了一个顶级捕食者进食策略发生变化的案例。
In September 2011, two harbour porpoises (Phocoena phocoena) presenting extensive traumatic lesions washed ashore in Belgium. Similar lesions, with large parts of skin and blubber missing, had not been recorded before on harbour porpoises in Belgium but were recently observed in a number of cases in neighbouring countries. We compared the lesions with the mouth and teeth structure of possible predators. The circumstances of the strandings, the observations during the necropsies, and the results of seal skull investigations pointed towards seals, presumably grey seals (Halichoerus grypus), as the prime suspects for having caused the death of both harbour porpoises. Although purely aggressive behaviour cannot be completely excluded, predation is considered most likely as part of the skin and blubber tissue of the harbour porpoises was missing. The grey seal is an opportunistic predator, feeding on a variety of fish and cephalopods, and occasionally even on crustaceans and seabirds, but predation on harbour porpoises, or any other marine mammal, had to our knowledge never been described. This finding might shed a new light on the cause of death of some of the other mutilated harbour porpoises recently stranded on southern North Sea beaches, and it presents a case of a change in the feeding strategy of a top predator.