ABSTRACT: Competition for prey resources among ecologically similar populations that occur in sympatry can be reduced by spatiotemporal resource partitioning. Understanding patterns of habitat use of cetaceans can be difficult since they are highly mobile and can have large home ranges. We used passive acoustic monitoring at 15 sites along the coast of Washington State, USA, to assess habitat use patterns of 2 sympatric populations of fish-eating killer whales Orcinus orca: northern residents (NRKW) and southern residents (SRKW). This area is part of the ocean distributions of a number of important runs of Chinook salmon Oncorhyncus tshawytscha, the preferred prey of both populations, and is proposed critical habitat for SRKW. We compared monthly occurrence of both populations at recorder locations grouped by their proximity to the Strait of Juan de Fuca to the north and the Columbia River to the south in one analysis and by their distance from shore in a second analysis. NRKW and SRKW were detected throughout the year with spring and fall peaks in occurrence. The northernmost sites accounted for 93% of NRKW detections, while less than half of SRKW detections were at these sites. SRKW were most frequently detected at nearshore sites (83% of detections), while the majority of NRKW detections were at mid-shelf and deep sites (94% of detections). This study provides further information about the habitat use of these resident killer whale populations with implications for their management and conservation.

中文翻译：

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被动声监测显示拟议关键栖息地中两种食鱼虎鲸Orcinus orca种群的时空隔离

摘要：通过时空资源分配，可以减少共生系统中生态相似的种群之间对猎物资源的竞争。了解鲸类栖息地的使用方式可能很困难，因为它们移动性强并且有较大的栖息地。我们在美国华盛顿州沿岸的15个地点使用了无源声学监测，以评估食鱼虎鲸Orcinus orca的2个同伴种群的栖息地利用模式：北部居民（NRKW）和南部居民（SRKW）。该地区是奇努克鲑鱼Oncorhyncus tshawytscha的许多重要游轮海洋分布的一部分，这两个种群的首选猎物，并被建议为SRKW的重要栖息地。在一项分析中，我们比较了记录器位置上两个种群的月度发生情况，根据一次分析，它们与北部的胡安·德富卡海峡相邻，而与南部的哥伦比亚河相邻，而在第二次分析中，它们与海岸的距离分组。全年检测到NRKW和SRKW，并出现春季和秋季高峰。最北端的站点占NRKW检测到的93％，而少于SRKW检测到的一半在这些站点。SRKW最常见于近岸站点（占检测的83％），而大部分NRKW检测都位于中层和深处（占检测的94％）。