Marine socio-ecosystems are complex systems characterized by strong interactions between natural resources exploited, human activities and governance. Many human activities rely on the resources that the ecosystem can provide. However, natural resources are common and variable and thus require particular management and adaptation from human activities. In addition, marine environments and activities are difficult to observe, assess or control. Supporting management of marine SES therefore requires the use of participatory integrated approaches such as the ComMod (Companion Modeling) approach. This approach builds simulations and gaming with the stakeholders of the territory to help sharing a common vision of the SES and its future and thus empowering stakeholders towards sustainable trajectories. Within the framework of the HOPOPoP project, a ComMod approach has been developed in the Iroise Sea red lobster fishery which is characterized by a biomass increase providing incentives to target this species in a context of a decrease observed in a number of other fish stocks. In a first step, the co-construction of a conceptual model with the stakeholders of the fishery will be built through interviews and workshops. This model will be used, in a second step, to create an agent-based simulation model which combines classical biological and socio-economic simulations of scenarios and role playing in order to help stakeholders explore consequences of decisions on the management of their activity. Stakeholders will be able to make virtual decisions and see how they impact the different elements of the socio-ecosystem.