Eradicating Common Populations of Invasive Species Involves Balancing Efficiency and Fairness

The effective eradication and control of harmful species are crucial for agriculture and for the conservation of ecosystems and biodiversity. Since harmful invasive species often spread over large areas, their eradication may necessitate cooperation among multiple agents, such as farmers, landowners, and countries. A key challenge is determining how the contributions could be allocated among the agents, such that no agent would benefit from unilaterally changing its contribution (Nash equilibrium). We introduce a dynamic game-theoretic model that incorporates invasive species population dynamics. Our findings reveal that, counterintuitively, in Nash equilibria, agents incurring lower annual costs from the species contribute more. Moreover, multiple Nash equilibria exist, and those with fewer contributing agents are more efficient, leading to faster eradication. This indicates that efficiency in managing biological populations often conflicts with fairness. Therefore, some agents may have to compromise on fairness for cost-effective project implementation, and policymakers and planners must balance fairness and efficiency when assigning eradication responsibilities among landowners or countries.