Abstract We compared the capture efficiency of three traditional sampling methods, hand captures at day, hand captures at night and captures by commercial baited traps (“Pirat type”) with a coarse mesh size of 10 × 45 mm, for the native crayfish species Austropotamobius torrentium (stone crayfish) and Astacus astacus (noble crayfish). These capture types are applied regularly in monitoring programs. Additionally, we tested modified traps with fine mesh size to capture stone crayfish. We hypothesized that the capture efficiency of the methods is different between the two species, different sex and size classes and seasons and that modified traps with small mesh size were more effective in capturing juvenile stone crayfish than traps with coarse mesh size. Hand captures at night were found to be the most effective sampling method for both species. It generates the highest relative abundances and is the least biased method in relation to size and sex of crayfish specimen. Hand captures at day result in lower capture rates than hand captures at night. However, there is a tendency to gather more small individuals and females in comparison to the night captures. Baited traps turned out to be completely inappropriate for capturing stone crayfish; even traps modified with small mesh size were not a suitable capture method. For noble crayfish all three methods seem to be suitable, depending on the sampling purposes. The relative differences between the methods did not change significantly during the seasons. However, when capture rates of all three methods were combined, September was found to be the month where the highest capture rates were achieved as both sexes of both species were on the peak of their activity.

中文翻译：

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评估三种监测德国本土小龙虾的方法的效率

摘要 我们比较了三种传统采样方法的捕获效率，白天手工捕获，夜间手工捕获和商业诱饵陷阱（“Pirat 型”）的捕获效率，粗网目尺寸为 10 × 45 mm，对于本地小龙虾物种 Austropotamobius torrentium（石龙虾）和Astacus astacus（高贵的小龙虾）。这些捕获类型在监视程序中定期应用。此外，我们还测试了具有细网孔尺寸的改良陷阱来捕获石螯虾。我们假设这些方法的捕获效率在两个物种、不同性别、不同大小等级和季节之间是不同的，并且小网孔尺寸的改良陷阱比粗网孔尺寸的陷阱更有效地捕获幼年石螯虾。发现夜间手工捕获是这两种物种最有效的采样方法。它产生最高的相对丰度，是与小龙虾标本的大小和性别相关的偏差最小的方法。白天手动捕获的捕获率低于夜间手动捕获。然而，与夜间捕获相比，有聚集更多小个体和雌性的趋势。事实证明，诱饵陷阱完全不适合捕获石螯虾；即使用小网格修改的陷阱也不是合适的捕获方法。对于贵重小龙虾，这三种方法似乎都适用，具体取决于采样目的。方法之间的相对差异在季节期间没有显着变化。然而，当所有三种方法的捕获率结合起来时，