The muskrat (Ondatra zibethicus) is an invasive species in Europe. The extensive waterways of the Netherlands provide ideal habitat for muskrats, and a large population established itself after arrival in 1941. A control program was put into effect immediately because muskrat burrowing can compromise the integrity of dikes and, hence, poses a significant public safety risk. The current (2015) annual catch of approximately 89,000 individuals is equivalent to approximately 0.30 muskrats/km of waterway, well above the national objective in spite of decades of effort. The control program is expensive (€35 M annually) and contested by animal rights groups. These factors created the need for a careful evaluation of the full range of control possibilities, from ‘no control’ to ‘extermination.’ As part of this, we experimentally evaluated the validity of a previously published correlation (based on historical data) between catch and effort. We raised or lowered removal effort (2013–2016) in a stratified random sample of 117 5‐km × 5‐km ‘atlas squares’ from the national grid. We found that catch‐per‐unit effort (CPUE) decreased after effort was increased, and rose after effort was decreased, by amounts slightly greater than expected based on the correlational data, though confidence intervals enclose zero. As anticipated, CPUE varied consistently and strongly between seasons. The biggest (and unanticipated) effects were those of the catch in the preceding 3 years (‘history’), and surrounding area (‘neighborhood’). Our experiment confirms estimates of intensity of control required to lower muskrat populations. These results will help with more effective allocation of control effort, and better‐informed evaluation of the economic costs of various control options. © 2020 The Authors. Wildlife Society Bulletin published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.

中文翻译：

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评估侵袭性麝香控制的大型实验

麝香鼠（Ondatra zibethicus）是欧洲的一种入侵物种。荷兰广阔的水道为麝香提供了理想的栖息地，并在1941年抵达后便建立了庞大的种群。由于麝香鼠的穴居可能损害堤防的完整性，因此立即实施了控制计划，因此构成了重大的公共安全隐患。尽管数十年的努力，目前（2015年）的年度捕捞量约为89,000人，相当于每公里水道约0.30麝香鼠，远高于国家目标。该控制程序昂贵（每年3500万欧元），并受到动物权利组织的质疑。这些因素导致需要仔细评估从“无控制”到“灭绝”的所有控制可能性。为此，我们通过实验评估了捕获和努力之间先前发布的相关性（基于历史数据）的有效性。我们从国家网格的117个5 km×5 km“地图集正方形”的分层随机样本中提高或降低了清除工作量（2013-2016年）。我们发现，尽管置信区间为零，但增加工作量后单位捕获量（CPUE）减少，而减少工作量后则增加，其数量略高于根据相关数据的预期。不出所料，CPUE在各个季节之间持续且强烈地变化。最大（也是未预料到的）影响是前三年（“历史”）和周围地区（“邻里”）的渔获物。我们的实验证实了降低麝香鼠种群所需的控制强度估计值。这些结果将有助于更有效地分配控制工作，并更好地评估各种控制方案的经济成本。©2020作者。Wiley Periodicals，Inc.代表“野生动物协会”出版的“野生动物协会公告”。