The restoration of seagrass meadows for the recuperation of macro and micro habitats in the area of Portinho da Arrábida is the objective of BIOMARES project, during 2007 and 2011, co-financed by Life-Nature European Commission Programme. But what is the added value of this initiative? This article tries to analyze the benefits and costs that may come from the Project. Marine resources in Portugal and in European Union have a reinforced attention, with the development of several strategic and territorial planning instruments that try to manage the coastal areas and the access and exploitation of resources. The concept of Sea Hyper-cluster achieves relevance nowadays. From the marine resources we focus seagrass meadows and their habitats in Portinho da Arrábida, once its influence in different economic issues, like fisheries or tourism is very important. In the end a undemanding approach to games theory and social optimum analysis will be done for the case of destruction of seagrass meadows in this area.