Introduced common carp ( Cyprinus carpio ) are a recognised threat to New Zealand’s freshwater ecosystems. In 2011, an invasive fish removal programme was undertaken in 16.8 ha Lake Ohinewai, a Waikato riverine lake. Active fish removal using netting and boat electrofishing was supported by installation of a one‐way exclusion barrier on the outflow to Lake Ohinewai. The barrier was designed to allow fish passage downstream out...