Fisheries managers efficiently sample reservoir Channel Catfish Ictalurus punctatus populations with tandem, baited hoop nets. However, catchability (the fraction of a fish stock caught with a defined unit of effort) of Channel Catfish with this gear and the size selectivity of this gear are not fully known. Furthermore, scientists have not identified a standard sampling period that maximizes catches while minimizing variation in catchability. Here, we estimated Channel Catfish population density (number/ha) and catchability with tandem, baited hoop nets using mark–recapture methods in three Ohio reservoirs during May–July 2016–2018. We tested for differences in catchability (1) among reservoirs; (2) among 50‐mm length categories; and (3) by week. We then tested CPUE as an index of density by simulating the sampling of populations with different densities based on observed variation in catchability and estimating the statistical power to detect density differences. We found that total catchability differed among study reservoirs, among length categories, and among sampling events but did not consistently change during the May–July sampling period. Catchability of 50‐mm length categories did not differ among reservoirs. The greatest catchability was observed for 400–649‐mm Channel Catfish. Our power analysis showed that we could detect a large (>2:1 effect sizes) difference in density with 80% power by using 20 or more sample sites. Furthermore, our length‐category‐specific catchability estimates provide information to reduce bias in size structure, growth, and mortality estimates derived from Channel Catfish samples collected with tandem, baited hoop nets. We encourage further development, validation, and application of tandem, baited hoop nets to better understand differences in reservoir Channel Catfish densities and size structures.

中文翻译：

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用诱饵环网串联索引水库Channel鱼种群密度和大小结构

渔业管理人员有效地对水库Channel鱼I鱼进行采样装有诱饵的环网的串联种群。但是，使用这种渔具的Cat鱼的可捕捞性（以规定的工作量捕捞的鱼群的比例）以及该渔具的尺寸选择性尚不完全清楚。此外，科学家还没有确定使捕捞量最大化同时使捕捞能力的变化最小化的标准采样期。在这里，我们使用标记捕获方法估算了2016年5月至7月7日在俄亥俄州的三个水库中的Cat鱼种群密度（数量/公顷）和使用网状诱饵网的可捕性。我们测试了储层之间的可捕获性差异（1）；（2）在50毫米长的类别中; （3）每周一次。然后，我们根据观察到的可捕获性变化模拟了具有不同密度的种群的采样，并估计了检测密度差异的统计能力，从而将CPUE作为密度的指标进行了测试。我们发现，总的可捕集性在研究储层之间，长度类别之间以及采样事件之间有所不同，但在5月至7月的采样期间并没有持续变化。在不同的储层中，长度为50 mm的类别的可捕获性没有差异。对于400–649 mm的Channel鱼，可捕获性最高。我们的功效分析表明，通过使用20个或更多采样点，我们可以在80％功效下检测到较大的（> 2：1效应大小）密度差异。此外，我们特定于长度类别的可捕获性估计值可提供信息，以减少规模结构，增长，和死亡率估算值来自使用诱饵环网串联收集的海Cat鱼样本。我们鼓励进一步开发，验证和应用串联诱饵式圈网，以更好地了解水库Channel鱼密度和大小结构的差异。