Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Seattle, Washington, United States of America.
Conservation Biology Division, Northwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Manchester Research Station, Manchester, Washington, United States of America.
PLoS One. 2021 Mar 3;16(3):e0247031. doi: 10.1371/journal.pone.0247031. eCollection 2021.
Understanding diet is critical for conservation of endangered predators. Southern Resident killer whales (SRKW) (Orcinus orca) are an endangered population occurring primarily along the outer coast and inland waters of Washington and British Columbia. Insufficient prey has been identified as a factor limiting their recovery, so a clear understanding of their seasonal diet is a high conservation priority. Previous studies have shown that their summer diet in inland waters consists primarily of Chinook salmon (Oncorhynchus tshawytscha), despite that species' rarity compared to some other salmonids. During other times of the year, when occurrence patterns include other portions of their range, their diet remains largely unknown. To address this data gap, we collected feces and prey remains from October to May 2004-2017 in both the Salish Sea and outer coast waters. Using visual and genetic species identification for prey remains and genetic approaches for fecal samples, we characterized the diet of the SRKWs in fall, winter, and spring. Chinook salmon were identified as an important prey item year-round, averaging ~50% of their diet in the fall, increasing to 70-80% in the mid-winter/early spring, and increasing to nearly 100% in the spring. Other salmon species and non-salmonid fishes, also made substantial dietary contributions. The relatively high species diversity in winter suggested a possible lack of Chinook salmon, probably due to seasonally lower densities, based on SRKW's proclivity to selectively consume this species in other seasons. A wide diversity of Chinook salmon stocks were consumed, many of which are also at risk. Although outer coast Chinook samples included 14 stocks, four rivers systems accounted for over 90% of samples, predominantly the Columbia River. Increasing the abundance of Chinook salmon stocks that inhabit the whales' winter range may be an effective conservation strategy for this population.
了解饮食对于保护濒危捕食者至关重要。南方居民虎鲸（Orcinus orca）是一种濒危物种，主要分布在华盛顿州和不列颠哥伦比亚省的外海和内陆水域。猎物不足已被确定为限制其恢复的因素之一，因此，清晰了解其季节性饮食是一个高度优先的保护事项。先前的研究表明，它们在内陆水域的夏季饮食主要由奇努克三文鱼（Oncorhynchus tshawytscha）组成，尽管与其他一些鲑鱼相比，这种三文鱼的数量较为稀少。在一年中的其他时间，当它们的出现模式包括其分布范围的其他部分时，其饮食仍然知之甚少。为了解决这一数据空白，我们于 2004 年至 2017 年 10 月至 5 月期间在萨利希海和外海海域收集了粪便和猎物残骸。我们使用视觉和遗传物种鉴定方法来鉴定猎物残骸，以及遗传方法来鉴定粪便样本，从而描述了南方居民虎鲸在秋季、冬季和春季的饮食特征。奇努克三文鱼全年都是重要的猎物，秋季占其饮食的 50%左右，冬季中期/早春增至 70-80%，春季增至近 100%。其他鲑鱼和非鲑鱼也对其饮食做出了重大贡献。冬季物种多样性相对较高，这表明可能缺乏奇努克三文鱼，这可能是由于季节性密度较低，因为南方居民虎鲸在其他季节倾向于选择性地食用这种鱼。大量的奇努克三文鱼种群被消耗，其中许多种群也处于濒危状态。尽管外海奇努克三文鱼样本包括 14 个种群，但四个河流系统的样本占比超过 90%，主要是哥伦比亚河。增加栖息在虎鲸冬季活动范围内的奇努克三文鱼种群的数量可能是保护这一物种的有效策略。
