Managing outbreaks of invasive species: Eradication versus suppression

Abstract

A framework is developed to evaluate eradication as one of three alternative management responses to an outbreak of an invasive species: eradication, suppression or no action. This framework can be used to establish under what conditions an eradication option could provide an expected net economic benefit, and whether this net benefit exceeds that of the other two options. The eradication option is more likely to be preferred in situations where there is an immediate export benefit that is derived from eradication of the outbreak, and also the uncertainty associated with the likely success of eradication is low.

Keywords:

• Invasive species
• eradication
• export benefit

Notes

¹ United Kingdom Department of Environment, Food and Rural Affairs, the ministry responsible for animal and plant health, quarantine, and management of invasive species in England and Wales.

² Ex ante is Latin term meaning ‘beforehand’. In this context, it is used to describe expected net benefit estimates of eradication made in the planning phase of invasion responses (i.e. prior to a campaign taking place).

³ Risk mitigation refers to actions taken to reduce the probability of entry and/or the total damage potentially inflicted by an invasive species. It is assumed in this analysis that entry and establishment routes would be closed as part of an eradication programme, thus protecting the benefits achieved from eradication for some time into the future.

⁴ Surveillance must demonstrate over a period of time following the final elimination of the outbreak population that the eradication has been successful—this may take a further 3–12 months and can be a significant element in the cost of eradication. Mumford (2004) found fruit fly free certification could cost as much as one-third of the total costs of eradication.

⁵ The OIE Agreement requires a ‘stamping out’ policy to be adopted by Member nations in which outbreaks are detected whereby infected and possibly infected animals are slaughtered and animal movement restricted to contain and eliminate the outbreak (OIE 2003).

⁶ Cook and Fraser (2002) use a spatial evaluation technique to examine the welfare implications of costly quarantine treatments on regionalized and centralized industries.

⁷ For instance, market restrictions imposed due to the disease Karnal Bunt can be severe, as indicated in Thorne et al. (2004), Brennan et al. (1992), Stansbury and Pretorius (2001).