1. Invasive species can cause population declines and extinctions of native species through several mechanisms including predation and competition. One such species, western mosquitofish (Gambusia affinis), is an invasive, aggressive predator and competitor of numerous freshwater species around the world that has caused precipitous declines of native species.
2. The Barrens topminnow (Fundulus julisia) is a spring‐endemic fish of the south‐eastern U.S.A., and the western mosquitofish limits its recruitment via predation of smaller individuals but there is also potential for competition (i.e. interference competition) between the species in laboratory trials. All of these negative interactions probably contribute to the Barrens topminnow's precipitous decline since the 1980s and the listing of the species as endangered by the U.S. Fish and Wildlife Service in late 2019. Ongoing conservation measures for Barrens topminnow include long‐term monitoring of populations and reintroductions through stocking of hatchery‐reared individuals into numerous sites.
3. Here, we investigate trends in Barrens topminnow and western mosquitofish occupancy and abundance over an 8‐year period (three or four generations for Barrens topminnow) and assess the effectiveness of a stocking programme. We also included habitat covariates including distance to the nearest downstream confluence, stream order, and habitat size.
4. Our findings revealed significant range‐wide Barrens topminnow declines in both occupancy and abundance were occurring over the 8‐year period. These declines were associated with the presence of western mosquitofish. Overall, the stocking programme of hatchery‐reared individuals did not significantly enhance or restore populations of Barrens topminnow but had a negative effect on topminnow abundance when western mosquitofish were present.
5. The lack of a positive effect of stocking hatchery‐reared individuals on Barrens topminnow populations and the long‐term population declines of Barrens topminnow suggest that propagation and stocking alone are not effective at creating self‐sustaining populations of the Barrens topminnow. The presence of western mosquitofish does not currently appear to be compatible with long‐term persistence of topminnow populations. Moving forward, conservation strategies will be needed to create and maintain mosquitofish‐free habitats, which may include eradication of mosquitofish, construction of barriers, or other actions.

中文翻译：

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评估因蚊虫入侵而在空间上濒临灭绝的北美顶级min的保护工作是否成功

1. 外来入侵物种可通过包括捕食和竞争在内的多种机制导致种群减少和自然物种灭绝。一种这样的物种，西部蚊子（Gambusia affinis），是世界上许多淡水物种的入侵性，侵略性捕食者和竞争者，已经造成了本地物种的急剧减少。
2. Barrens topminnow（Fundulus julisia）是美国东南部的一种春季特有鱼类，西部蚊子鱼类通过较小个体的捕食来限制其捕捞，但是在实验室试验中该物种之间也存在竞争（即干扰竞争）的潜力。 。所有这些负面的相互作用都可能导致Barrens topminnow自1980年代以来的急剧下降，以及该物种在2019年底受到美国鱼类和野生动物服务局的威胁而被列为濒危物种。Barrens topminnow正在进行的保护措施包括对种群的长期监测和重新引入。通过将孵化场饲养的个体放养到众多地点。
3. 在这里，我们调查了过去8年间（Barrens topminnow的3或4代）Barrens topminnow和西部蚊子的占用和丰度的趋势，并评估了放养计划的有效性。我们还包括栖息地协变量，包括到最近的下游汇合处的距离，溪流次序和栖息地大小。
4. 我们的发现表明，在过去8年中，整个Barrens topminnow的占用率和丰度都出现了显着下降。这些下降与西部蚊子的存在有关。总体而言，孵化场饲养的个体的放养计划并未显着增强或恢复贫瘠的稀有top的种群，但当存在西部蚊鱼时，对稀有top的丰度产生了负面影响。
5. 孵化场饲养的个体缺乏对Barrens topminnow种群的积极影响，以及Barrens topminnow的长期种群减少表明，仅繁殖和放养并不能有效地创造Barrens topminnow的自我维持种群。目前，西部蚊子的存在似乎与顶级小now种群的长期存留不相容。展望未来，将需要采取保护策略来创建和维护无蚊鱼的栖息地，其中可能包括消灭蚊虫，建造障碍物或采取其他行动。