A geographic assessment of establishment risk for tilapia, a group of potentially invasive aquatic species

As invasive species pose increasing threats to native species and their habitat, quantitative assessments of risk are needed to aid management decision-making regarding transport and culture of non-natives. We produced a spatially-explicit risk assessment model for tilapia establishment in Georgia based on water temperature. Thermal tolerance experiments coupled with Mayfield hierarchical logistic regression showed that daily probability of survival for tilapia is dependent upon temperature drop rate, average sustained temperature, tilapia strain, and weight-length ratio. Model results were directly applied to stochastically-simulated statewide water temperature predictions. Simulation results indicated that while long-term survival probabilities are low in Georgia, much of the state remains at high risk, indicating that survival is likely to occur once every three years. Survival probabilities are significantly lower in the northern areas than the coastal plain. This quantitative, geographically explicit risk assessment can inform regional management decisions by balancing economic benefits and potential for ecological damage.