Synthesising Support for the Entrainment Hypothesis Through Spatially Explicit Life Cycles, Vagrancy and Collapse of Atlantic Tarpon (Megalops atlanticus)

Abstract

Understanding spatial dynamics and migratory behaviours of fish populations is essential for effective fisheries management. We focus on the migratory Atlantic tarpon (Megalops atlanticus) to explore how movement strategies and spatial life cycle patterns shape stock dynamics, contingent structure and mechanisms for collapse and recovery. The entrainment hypothesis posits that migratory routes are socially transmitted from experienced repeat spawners to younger conspecifics, resulting in distinct contingents within a population. Using a combination of literature review, life history data, mark‐and‐recapture records and electronic tagging, we evaluated five biological hypotheses related to entrainment mechanisms, habitat conservatism and phenotypic plasticity within Atlantic tarpon populations. Our findings provide evidence for migratory connectivity and the role of entrainment in shaping Atlantic tarpon contingent structure across the Western Atlantic. Movement and mark‐and‐recapture data revealed spatially discrete contingents with some intermixing, highlighting behavioural conservatism and phenotypic plasticity. Examples of vagrancy showed Atlantic tarpon caught far from their capture contingent, suggesting vagrant movements may contribute to colonising new habitats under suitable conditions. Straying by a subset of individuals may also increase the recovery and resilience of Atlantic tarpon stocks following collective memory loss in migratory routes. Research on contingent structure, larval recruitment patterns and abundance trends is needed to inform management measures to ensure the maintenance of migratory knowledge. This approach provides a framework for understanding Atlantic tarpon and other migratory marine fish stock dynamics, while underscoring the importance of coordinated management and conservation efforts across contingent boundaries.