Invasive crayfish species were first documented in Switzerland in the 1970s. Today, North American crayfish species dominate in most major lakes and streams in Switzerland. In combination with the crayfish plague, they pose a substantial threat to our native crayfish. Over the past 20 years, various techniques have been applied to reduce negative impacts of these invasive crayfish in Switzerland: eradication (temporary drainage or destruction of a water system, biocides), suppression (intensive trapping, electricity introduction of predatory fish) and containment (construction of crayfish barriers). Temporary drainage or filling-in of isolated ponds, in combination with calcium hydroxide application has been successful in eradicating populations of invasive crayfish. However, trapping and introduction of predatory fish led to a reduction in population density but neither method has ever caused the extinction of a population. Invasive crayfish have not yet reached crayfish barriers, therefore, long-term functionality of these barriers still needs to be proven. Nevertheless, functional controls with native crayfish have shown that barriers prevent their upstream movement. Implementation of crayfish barriers is the most promising method to protect native crayfish from displacement by invasive crayfish species. Many measures are expensive, time consuming, and show little or no success in controlling invasive crayfish. Therefore, we recommend to focus on implementing drastic measures, such as filling-in or draining of isolated waters or a combination of various methods to maximise the reduction of population size.

中文翻译：

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瑞士控制入侵小龙虾物种的措施：成功案例？

1970 年代，瑞士首次记录了入侵小龙虾物种。今天，北美小龙虾种类在瑞士的大多数主要湖泊和溪流中占主导地位。与小龙虾瘟疫相结合，它们对我们的本地小龙虾构成了重大威胁。在过去的 20 年里，瑞士采用了各种技术来减少这些入侵小龙虾的负面影响：根除（临时排水或破坏水系统、生物杀灭剂）、抑制（密集诱捕、对掠食性鱼类通电）和遏制（建造小龙虾屏障）。临时排水或填充孤立的池塘，结合应用氢氧化钙，已成功根除入侵小龙虾种群。然而，捕食性鱼类的诱捕和引入导致种群密度降低，但两种方法都没有导致种群灭绝。入侵的小龙虾尚未达到小龙虾的屏障，因此，这些屏障的长期功能仍有待证明。然而，对本地小龙虾的功能控制表明，障碍阻止了它们的上游移动。实施小龙虾屏障是保护本地小龙虾免受入侵小龙虾物种迁移的最有前途的方法。许多措施既昂贵又耗时，并且在控制入侵小龙虾方面几乎没有成功。因此，我们建议重点采取严厉措施，例如填充或排放孤立水域或多种方法的组合，以最大限度地减少人口规模。