Evaluating management options for aquatic invasive species: concepts and methods

In analyses that attempt to estimate the costs of species invasions, it has been typical to report the costs of management and/or to multiply per-unit costs by the number affected to arrive at a total. These estimates are of limited value for most policy questions. We start our discussion by recognizing that biological pollutants such as aquatic invasive species are like conventional pollutants in important ways and appeal to the well-developed literature on conventional pollution to guide our thinking into how best to conceptualize the problem. We use a standard pollution control framework to identify the margins over which costs and benefits should be estimated to guide wise decision-making. We then use examples from the literature to illustrate how transactions in related markets can be used to estimate the benefits of management. The roles of adaptation, mitigation, and species population growth have particular relevance and are highlighted. In the final section of the paper, we think through the conditions under which investing in genetic biocontrol methods would be economically justified.