The migration game in habitat network: the case of tuna

Abstract

Long distance migration is a widespread process evolved independently in several animal groups in terrestrial and marine ecosystems. Many factors contribute to the migration process and of primary importance are intra-specific competition and seasonality in the resource distribution. Adaptive migration in direction of increasing fitness should leads to the ideal free distribution (IFD) which is the evolutionary stable strategy of the habitat selection game. We introduce a migration game which focuses on migrating dynamics that lead to the IFD for age-structured populations in time varying environments where dispersal is costly. The model assumes a network of habitats and predicts migration dynamics between these habitats and the corresponding population distribution. When applied to Atlantic bluefin tunas it predicts their migration routes and their seasonal distribution. The largest biomass is located in the spawning areas which have also the largest diversity in the age-structure. Distant feeding areas are occupied on a seasonal base and often by larger individuals, in agreement with empirical observation. Moreover we show that only a selected number of migratory routes emerge as those effectively used by tunas.