Meta-Population Dynamics in the American Eel and the Importance of Larval Distribution

Modelling the population dynamics of American Eel (Anguilla rostrata) is challenging because its life history exhibits marked geographic variation, despite a panmictic breeding system. To assist in conservation efforts, we developed the first species-wide meta-population model that incorporates all life stages. Partitioning the geographic distribution into distinct life history zones with geographically-specific inputs, we used this model to compare population dynamics, sensitivity to perturbations, and responses to anthropogenic harm across larval distribution hypotheses (e.g., maternal effects vs. random distribution). Long-term population sensitivity to changes in vital rates was relatively robust across hypotheses, but expected stage and geographical distributions varied dramatically. Projected transient dynamics (short term fluctuations as abundance approaches long term stability) were influenced by larval distribution. Random larval distribution led to rapid convergence to stability, while strong maternal effects led to decades of (often counterintuitive) delay including apparent growth of a declining population, or an unexpected influence of one zone upon the stock of another. These results highlight the importance of understanding larval distribution mechanisms, consideration of the entire meta-population, and incorporating transient dynamics into management plans.