Alteration of river systems around the world has created novel environments that have been fragmented, homogenized, or transformed from their natural state, thus posing challenges for understanding how fish populations function. The Missouri River has undergone significant alteration through reservoir construction and channelization. Channel Catfish Ictalurus punctatus and Flathead Catfish Pylodictis olivaris both reside in various fragmented sections of the river, and there is a substantial gap in knowledge of how catfishes synchronously function in this modified system. From 2009 to 2018, we assessed catfishes with baited hoop nets and low‐frequency electrofishing among four different areas: upper and lower unchannelized segments and upper and lower channelized segments. Differences in population demographics and dynamics occurred for both species among segments. Both the highest and lowest relative abundances for Channel Catfish occurred in channelized segments, and Flathead Catfish relative abundance was lowest in both unchannelized segments. Subadult growth rates for both catfish species were greater in channelized segments. Channel Catfish mortality was highest in channelized segments, which was consistent with the maximum ages found in channelized (age 9) versus unchannelized (age 15) segments. High‐flow events in 2010 and 2011 led to an increase in recruitment, but populations declined in subsequent years. This long‐term assessment revealed spatial and temporal differences in population dynamics among varying levels of anthropogenic alteration. Our study illustrates how river modification and extreme climatological events may impact and structure catfish populations. These data provide a basis for assessing catfish throughout the Missouri River system and offer insight into how catfish populations in other altered large‐river systems might function.

中文翻译：

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美国内布拉斯加州密苏里河河流相地貌条件改变的河段among鱼种群特征

世界各地河流系统的变化创造了新颖的环境，这些环境已经从其自然状态分散化，同质化或转变，从而对理解鱼类种群的功能构成了挑战。密苏里河经过水库建设和渠道化而发生了重大变化。槽Cat鱼Ictalurus punctatus和平头Cat鱼Pylodictis olivaris两者都生活在河流的各个零散部分中，在这种改良系统中cat鱼如何同步运行的知识上存在很大差距。从2009年到2018年，我们在四个不同区域（上，下无通道段和上，下通道化段）之间评估了带有诱饵的环网和低频电鱼的cat鱼。两个物种在种群之间的人口统计学和动力学差异。槽Cat鱼的相对丰度最高和最低都出现在通道化段中，而平头Cat鱼的相对丰度在未通道化段中最低。这两种cat鱼的亚成体生长率在通道化部分均较高。海沟Cat鱼死亡率在海沟部分最高，这与渠道化（9岁）和未渠道化（15岁）细分中的最大年龄相符。2010年和2011年的高潮事件导致招聘人数增加，但随后几年的人数有所下降。这项长期评估揭示了不同程度的人为改变之间人口动态的时空差异。我们的研究说明了河流改造和极端气候事件如何影响和构造cat鱼种群。这些数据为评估整个密苏里河系统中的cat鱼提供了基础，并提供了对其他经过改建的大型河流系统中cat鱼种群如何运作的见解。这项长期评估揭示了不同程度的人为改变之间人口动态的时空差异。我们的研究说明了河流改造和极端气候事件如何影响和构造cat鱼种群。这些数据为评估整个密苏里河系统中的cat鱼提供了基础，并提供了对其他经过改建的大型河流系统中cat鱼种群如何运作的见解。这项长期评估揭示了不同程度的人为改变之间人口动态的时空差异。我们的研究说明了河流改造和极端气候事件如何影响和构造cat鱼种群。这些数据为评估整个密苏里河系统中的cat鱼提供了基础，并提供了对其他经过改建的大型河流系统中cat鱼种群如何运作的见解。