title: A historical perspective on the effects of trapping and controlling the muskrat (Ondatra zibethicus) in the Netherlands.
abstract: BACKGROUND
  The muskrat is considered to be a pest species in the Netherlands, and a year-round control programme is in effect. We aimed to evaluate the effectiveness of this programme using historical data on catch and effort collected at a provincial scale.
  
  
  RESULTS
  The development of the catch differed between provinces, depending on the year of colonisation by muskrat and the investment of effort (measured as field hours). The catch did not peak in the same year for the various provinces, and provinces that were colonised earlier in time took longer to attain the peak catch. Trapping resulted in declining populations, but only after a certain threshold of annual effort in trapping had been surpassed. On average, populations were observed to decline when the annual effort exceeded 1.4 field hours per km of waterway for several successive years. Having reached a phase of greater control, control organisations tended to reduce effort.
  
  
  CONCLUSIONS
  We conclude that control measures can make muskrat populations decline, provided that the effort is commensurate with the population size. Our study emphasises that experimentation is needed to confirm the causality of the findings, to establish the relation with damage or safety risk and to derive an optimal control strategy. © 2016 Society of Chemical Industry.
authors.affiliation: Computational Geo-Ecology Group, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: E Emiel
authors.initials: EE
authors.lastname: van Loon
authors.affiliation: Altenburg & Wymenga Ecological Consultants, Veenwouden, The Netherlands.|Community and Conservation Ecology - Centre for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands.
authors.forename: Daan
authors.initials: D
authors.lastname: Bos
authors.affiliation: Resource Ecology Group, Wageningen University, Wageningen, The Netherlands.
authors.forename: Caspara J
authors.initials: CJ
authors.lastname: van Hellenberg Hubar
authors.affiliation: Resource Ecology Group, Wageningen University, Wageningen, The Netherlands.|Centre for Wildlife Ecology, Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.
authors.forename: Ron C
authors.initials: RC
authors.lastname: Ydenberg
mesh_terms: D000818:Animals; D003411:Arvicolinae; D049673:History, 20th Century; D049674:History, 21st Century; D058865:Introduced Species / Q000266:history / Q000706:statistics & numerical data; D009426:Netherlands; D010571:Pest Control / Q000266:history* / Q000379:methods / Q000706:statistics & numerical data; D011156:Population Density; D045483:Rivers
keywords: historical data; muskrat; pest species; population dynamics; trapping intensity