The Various Dilemmas of Assisted Migration for Slow-Moving Species

Ecologists recognize that many species will not migrate rapidly enough to keep up with shifting ecosystem conditions due to climate change. Assisted migration was proposed several decades ago as a strategy to help maintain populations of slow-moving species. However, many scientists see assisted migration as problematic, largely because its potential to preserve species stands in direct tension with its potential to produce invasion by the focal species, thereby threatening the recipient ecosystem. Scholarly debate on this topic has intensified during the last three years and threatens to produce a stalemate in policy and action on the issue. We take stock of the academic literature on this topic and identify possible avenues toward consensus in what might otherwise become an intractable ethical and policy problem. We tease apart the arguments in the debate, distinguishing among the direct risks and benefits to species, ecosystems and society on the one hand, and other arguments regarding scientific justification, evidence-base and feasibility on the other.  We present a conceptual framework to help scientists and policy makers find common ground and work towards case- and context-specific solutions.