Assessing the efficacy and ecology of biocontrol and biomanipulation for managing invasive pest fish

1. Management of non-native species aims to prevent biological invasions using actions including control and containment of the potential invader. Biocontrol and biomanipulation strategies are used frequently to reduce population sizes of non-native species and reduce their ecological impacts and dispersal rates. 2. Assessments of the efficacy of biocontrol and biomanipulation actions for managing non-native pest fish, and the ecological mechanisms involved, were studied here using lentic populations of the invasive fish Pseudorasbora parva. Biocontrol was through release of the indigenous piscivorous fish Perca fluviatilis and biomanipulation through intensive fish removals. 3. A combined biocontrol and removal programme was completed in an invaded pond over two reproductive seasons. Almost 10 000 P. parva were removed, with cumulative removal numbers significantly related to their decreased abundance (>60 to <0·1 m−2). Ten adult P. fluviatilis were also released initially and re...