Eradication economics for invasive alien aquatic plants.

Although there is a sizeable budget for biosecurity management in New Zealand, there will never be sufficient resources to intervene in all incursions of harmful species, including invasive freshwater plants. Given the inherent complexity in making decisions on interventions, responses are often decided in relation to specific incursions as they happen within their particular context. This paper uses New Zealand case studies to test if there are general economic principles related to intervention in invasive freshwater plants which can be used to improve decision-making. The general principles were; the sooner eradication is started and/or the smaller the incursion size, the lower the cost will be; eradication is more expensive than alternative responses in the short term but is cheaper than long term impacts of no intervention and/or ongoing control programs; and preventing new incursions is cheaper in the long run than eradication. The three principles were considered to be logical in an economic sense and can contribute to supporting intervention decision-making at a macro-level (i.e. across the majority of incursions) and provide more holistic outcomes for society in relation to management programs. [ABSTRACT FROM AUTHOR]