Résumé
In the case of sea turtles, migrating thousands of kilometers, spatial configuration plays a very critical role with important consequences at population level. Individual based modeling offers a great opportunity to take space explicitly into account in a very intuitive manner. To study the role of regional configuration in population reproductive potential, we developed a computer simulation on green turtles Chelonia mydas in the Western Indian Ocean (WIO). Our simulation world explicitly represents the WIO region. Turtles are modeled as individuals that can feed, migrate or breed. Nesting sites and feeding grounds have been accurately implemented according to current knowledge in the region. Each turtle is associated with an energetic status. Energy intake takes place exclusively on feeding grounds. Energy expenditure is dependent on turtle action. At this stage, only adult individuals are considered. Simulations are run over time for a range of energetic parameters. The simulation results helped us to assess how the WIO spatial structure drives the reproductive potential of green turtle populations from various rookeries. It also allowed pointing out the possible migrating roads between well identified breeding and feeding sites. Moreover part of the conclusions has been validated by early results from a regional satellite tagging campaign. Another interesting output of the model is to empirically assess the consequences of space and energetic parameters over the individual remigration interval under different behavioral hypothesis. It is also interesting to notice that the modeling process itself helps in apprehending the biological subject because individual-based modeling requires very precise description of the underlying system. Finally, a considerable asset of our model framework is that it would require few efforts, if any, to be applied elsewhere outside the WIO.