The introduction of invasive species has resulted in negative impacts to aquatic ecosystems and is cited as the second leading cause of fish extinctions. In the southwestern United States, low diversity and high levels of endemism increase the deleterious effects of these introductions. Near the southern edge of their range, the last remaining population of native Coastal Rainbow Trout Oncorhynchus mykiss irideus in San Diego County, California, inhabits the West Fork San Luis Rey River (WFSLRR). The nonnative Black Bullhead Ameiurus melas was discovered in the WFSLRR in 2007, elevating concern over this small population of Coastal Rainbow Trout. Preliminary surveys found that baited minnow traps set overnight were effective at capturing Black Bullhead; therefore, a removal project was initiated. Crew members set baited traps at the upstream end of the Coastal Rainbow Trout distribution in the evening (maximum = 72 traps/trip) and checked the traps the following morning. Four two‐night trips were completed in 2016, removing 1,315 Black Bullhead. The initial Black Bullhead population was estimated as 1,361 fish by a depletion function. Follow‐up surveys in 2017 and 2018 captured no Black Bullhead. Prolonged drought conditions in California during the removal effort may have concentrated the Black Bullhead into pools, facilitating this rare complete eradication of an invasive fish species.

中文翻译：

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从南加州的河源鳟鱼溪中去除黑头鱼

外来入侵物种的引入对水生生态系统造成了负面影响，被认为是造成鱼类灭绝的第二大原因。在美国西南部，多样性低和地方病流行程度高，增加了这些引进的有害影响。在其山脉的南部边缘附近，最后剩下的本地沿海虹鳟Oncorhynchus mykiss irideus位于加利福尼亚州圣地亚哥县，居住于西叉圣路易斯雷河（WFSLRR）。非本地的黑牛头Ameiurus melas于2007年在WFSLRR中被发现，这引起了对沿海虹鳟这一小种群的关注。初步调查发现，放置在夜间的诱饵小鱼now可有效捕获黑头黑头。因此，启动了一个清除项目。机组人员在傍晚在沿海虹鳟分布的上游端设置诱饵诱捕器（最多= 72个诱捕器/行程），并于第二天早晨检查诱捕器。2016年完成了四次两夜旅行，移除了1,315头黑头黑头。根据枯竭函数，最初的黑牛头种群估计为1,361条鱼。2017年和2018年的后续调查未发现黑头党。在拆除工作期间，加利福尼亚州长期干旱，可能已将黑牛头犬集中到了水池中，