Bioeconomic approach to risk assessment for invasive animals in trade in the United States

Background/Question/Methods Every year international trade in exotic animals brings many thousands of non-native species to the United States. These species support a large industry that makes desirable species available for pets, food, biological experiments, bait, and other uses. Although most imported species generate net economic benefits, a subset become invasive; they escape captivity, become established, spread, and cause serious economic and environmental harm. A challenge for ecologists is to develop predictive tools so that likely invaders can be identified and managed accordingly. Since the latent status (invasive/non-invasive) of a newly proposed species for import cannot be known beforehand with certainty, the challenge is to determine when it is rational to apply the predictions as policy. There is a tradeoff between the benefits from preventing invasions and the costs from preventing the import of species incorrectly identified as invasive. Bioeconomic models have been applied to the trade in horticultural plants, but the trade in animals, and basic animal biology, are very different and require different approaches to both ecological predictions and economic models. Here, we present recent work developing risk assessment tools and assess the conditions under which implementing such a screening system is expected to improve overall welfare.

Results/Conclusions We created risk assessment tools for mollusks and fishes introduced to the United States through trade. The mollusk tool extends our previous work and includes consideration of hitch-hiking parasites and pathogens. It assigns >80% of species to their correct class (i.e., invasive or not). For fishes, we concentrated on the relationship between previous invasion history and likelihood of future impacts. This tool has similar accuracy (i.e., >80%), which we use as a benchmark for risk assessment tools that could be created for other animal taxa. We gathered information about the number of species in trade and how many have become invasive. Depending on taxonomic group, between 1 and 14% of species in trade in the 1970s are now established. Economic costs of these species include, for example, the more than $300,000 being spent this year to develop control methods for Burmese python in the Florida Everglades. We incorporated these results into an economic decision model to determine when it is worth applying ecological predictions of invasiveness. Preliminary results show that risk assessment accuracies of ≥80% are required. Consideration of non-market costs, which are difficult to quantify and were not included in this model, would reduce the required risk assessment accuracy.