The commercially, recreationally, and culturally important Fraser River Sockeye Salmon Oncorhynchus nerka has experienced a productivity decline over the past 3 decades, which—along with greater temporal variation in annual abundance (i.e., cyclic dominance)—may at least partly be due to Steller sea lion Eumetopias jubatus (SSL) predation on returning adult salmon. This assumes that SSLs residing around northern Vancouver Island (British Columbia, Canada) target Sockeye Salmon for just a few weeks during the peak of their run. It is a reasonable enough assumption to warrant immediate priority for field research on SSL behavior and diets during the migration period. We evaluated the plausibility of the assumption with a variety of approaches ranging from simple estimates of maximum SSL consumption to partitioning of observed marine mortality rates and analysis of SSL foraging behavior to show that SSLs could have caused the decline in productivity and abundance of Fraser River Sockeye Salmon.

中文翻译：

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斯特勒海狮捕食是否影响了弗雷泽河红鲑鱼的生存？

在商业，休闲和文化上都很重要的弗雷泽河红鲑鱼Oncorhynchus nerka在过去的30年中经历了生产力下降，这与年度丰度的较大时间变化（即周期性优势）至少部分地归因于Steller海狮Eumetopias jubatus（SSL）捕食成年鲑鱼。假设居住在温哥华岛北部（加拿大不列颠哥伦比亚省）周围的SSL在运行高峰期间仅以Sockeye Salmon为目标。这是一个足够合理的假设，可以保证在迁移期间立即对SSL行为和饮食进行现场研究。我们通过多种方法评估了该假设的合理性，包括从最大SSL消耗的简单估计到观察到的海洋死亡率的划分以及对SSL觅食行为的分析，以显示SSL可能导致了Fraser River Sockeye的生产力和丰度下降。三文鱼。