Summary of information on the use made of the ecosystem of the Patagonian Sea by seabirds and marine mammals. These top predators require considerable space and resources and are vulnerable to many human activities. This makes them good indicators of the status of conservation of the ecosystem. The detailed analysis contained in this Atlas provides useful basic scientific information essential for implementing the vision of integrated ecosystem management. In particular it suggests that there is a need to create a network of marine areas, under special considerations of biodiversity management, which will incorporate those open sea environments which are linked to key coastal areas.