Dramatic increase in sea otter mortality from white sharks in California
Dramatic increase in sea otter mortality from white sharks in California
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DOI：
10.1111/mms.12261
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发表时间：
2016-01-01
影响因子：
2.3
通讯作者：
Ames, Jack A.
中科院分区：
文献类型：
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作者：
Tinker, M. Tim;Hatfield, Brian B.;Ames, Jack A.
尽管南方海獭（Enhydra lutris nereis）不被认为是白色鲨鱼（Carcharodon carcharias）的猎物，但鲨鱼仍然会咬海獭。我们分析了加州海獭被鲨鱼咬伤的时空趋势，评估了自1985年以来收集的1,870具海獭尸体被鲨鱼咬伤的频率。自2003年以来，被鲨鱼咬伤的搁浅海獭的比例急剧增加，白色鲨鱼咬伤的海獭尸体现在占到了被发现海獭尸体的50%以上。这一趋势在该范围的南部最为明显，从埃斯特罗湾到Point Conception，鲨鱼咬伤频率增加了8倍。季节性趋势也很明显：大多数被鲨鱼咬伤的尸体在夏末和秋季被发现;然而，鲨鱼咬伤频率升高的时间已经延长。这些趋势的原因尚不清楚，但可能的促成因素包括白色鲨鱼数量增加和/或白色鲨鱼行为和分布的变化。特别是，被鲨鱼咬伤的海獭的时空模式与鳍足类动物数量的增加相匹配，而白色鲨鱼获得的海洋哺乳动物猎物的增加可能导致更多的鲨鱼在海獭和鳍足类动物所利用的近岸沃茨花费更多的时间。
Although southern sea otters (Enhydra lutris nereis) are not considered prey for white sharks (Carcharodon carcharias), sharks do nonetheless bite sea otters. We analyzed spatial and temporal trends in shark bites on sea otters in California, assessing the frequency of shark bite wounds in 1,870 carcasses collected since 1985. The proportion of stranded sea otters having shark bites has increased sharply since 2003, and white shark bites now account for >50% of recovered carcasses. The trend was most pronounced in the southern part of the range, from Estero Bay to Point Conception, where shark bite frequency has increased eightfold. Seasonal trends were also evident: most shark-bitten carcasses are recovered in late summer and fall; however, the period of elevated shark bite frequency has lengthened. The causes of these trends are unclear, but possible contributing factors include increased white shark abundance and/or changes in white shark behavior and distribution. In particular, the spatiotemporal patterns of shark-bitten sea otters match increases in pinniped populations, and the increased availability of marine mammal prey for white sharks may have led to more sharks spending more time in nearshore waters utilized by both sea otters and pinnipeds.