The establishment of nonnative predators can have devastating consequences for native fish communities, but predation rates are often difficult to quantify due to spatial and temporal variation in predator foraging behavior. Predation by Channel Catfish Ictalurus punctatus throughout the Colorado River basin potentially threatens the recovery of native fishes. Because Channel Catfish are highly opportunistic feeders, an understanding of how piscivory by this species impacts prey populations should help to guide management in invaded systems. We used laboratory observations to model temperature‐dependent stomach evacuation rates and combined those estimates with field‐collected diet data to derive annual consumption across a 152‐km reach of the San Juan River (New Mexico, Colorado, and Utah). In the field, stomach fullness increased with water temperature while the probability of observing fish prey in the diet increased with TL of Channel Catfish and water turbidity. Based on estimates of daily ration, diet composition, and Channel Catfish population demographics, we estimated the San Juan River population’s fish consumption to be 4.9 kg·ha⁻¹·year⁻¹ (95% CI = 4.0–6.1 kg·ha⁻¹·year⁻¹) in 2018 and 2.3 kg·ha⁻¹·year⁻¹ (95% CI = 1.8–2.8 kg·ha⁻¹·year⁻¹) in 2019. Native fishes accounted for 54% of the fish biomass consumed, which included two incidents of endangered Colorado Pikeminnow Ptychocheilus lucius consumption. Although these estimates should help managers to assess the predatory threat of Channel Catfish, additional information, such as the efficacy of nonnative control and prey population compensatory responses, will likely be necessary to develop robust management strategies aimed at reducing the predatory impacts of this nonnative species on native fish assemblages.

中文翻译：

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沙漠河中非本地河Channel鱼对本地鱼类的消费量化

外来捕食者的建立会对当地鱼类群落造成毁灭性后果，但是由于捕食者觅食行为的时空变化，捕食率通常难以量化。海峡Cat鱼Ictalurus punctatus的捕食整个科罗拉多河流域都有可能威胁到本地鱼类的恢复。由于海Cat鱼是高度机会饲养者，因此了解该物种的食肉动物如何影响猎物种群应有助于指导入侵系统的管理。我们使用实验室观察来模拟温度依赖的胃排空率，并将这些估计值与现场收集的饮食数据结合起来，得出圣胡安河（新墨西哥州，科罗拉多州和犹他州）152公里段的年消费量。在田间，胃的饱满度随水温的升高而增加，而在日粮中观察到猎物的概率则随海Cat鱼的TL和水混浊而增加。根据每日口粮，饮食组成和海Cat鱼种群人口统计数据的估算，^-1 ·年^-1（95％CI = 4.0–6.1 kg·ha ^-1 ·年^-1）在2018年和2.3 kg·ha ^-1 ·年^-1（95％CI = 1.8–2.8 kg·ha ^-1 · 2019年（- ^1年）。本地鱼类占鱼类生物量消耗的54％，其中包括两次濒临灭绝的科罗拉多Pikeminnow Ptychocheilus lucius事件消费。尽管这些估计值应有助于管理人员评估Channel鱼的掠夺性威胁，但可能需要更多信息，例如非本地控制的有效性和猎物种群的补偿性对策，以制定旨在减少该非本地物种的掠食性影响的强有力的管理策略在本地鱼群上。