Carp as an Invasive Species

School of Science, Faculty of Science and Engineering, Th e University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand.

a Email: b.hicks@waikato.ac.nz b Email: n.ling@waikato.ac.nz *Corresponding author

Brendan J. Hicksa,* and Nicholas Lingb

Introduction

The common carp is listed among the eight most invasive fi sh species on the list of “One hundred of the world’s worst invasive alien species” (https:// www.issg.org/database/species/; Cambray 2003). The major impacts of common carp are typically regarded as reduced water quality and destruction of aquatic vegetation by uprooting it, but this explains only a small fraction of the problems posed by common carp as an invasive species. In many countries, carp are considered a noxious pest due to their disruptive benthic feeding behaviour, which can resuspend sediments, undermine river banks and dislodge macrophytes (Roberts et al. 1995, Williams et al. 2002, Bajer et al. 2009, Hicks et al. 2012). Resuspension of benthic sediments also increases turbidity, which reduces the amount of light available to macrophytes for photosynthesis, which leads to macrophyte collapse (Gehrke and Harris 1994, Rowe 2007). The potential impacts that carp may have on water bodies is exacerbated because they are long-lived, highly fecund and can exist at extremely high densities (e.g., 3,000 kg/ha) (Harris and Gehrke 1997). Accordingly, concerns have also been raised regarding the potential impact high densities of carp may have on native fi sh populations through mechanisms such as interspecifi c competition and habitat destruction (Gilligan and Rayner 2007). Paradoxically, common carp are themselves at risk in their native range from other invaders, e.g., Carassius gibelio in the Czech Republic (Lusk et al. 2010).