The estuary of the Amazon River comprises the area with influence of the tides, where the Marajó archipelago is located with its many islands inhabited by traditional communities that live from agroextrativism. This region has one of the lowest Human Development Index (0.489) in Brazil and 87.28% of the population is vulnerable to poverty. In this context, the açaí (Euterpe oleracea Mart.) emerges as a product from the local biodiversity with immense importance in food security, having become the driving force for the Marajó socioeconomic development. Participatory research conducted in 2018, in the municipality of Afuá (Pará), with 135 families of Ilha do Meio Agroextractivist Settlement Project, showed that the açaí constitutes on average 94.5% of the families' income, with an annual revenue of about six thousand US dollars per family. However, 83% of the interviewed families do not have the habit of saving and at the end of the harvest season they are deprived of resources. On the other hand, the açaí economy has generated an improvement in the families' quality of life and consumption patterns. It has also changed their eating habits and the way they use the forest. As a main conclusion, the study points out the need to discuss new market strategies for the diversification of production in order to use other fruits, seeds and oils. Improvement of the financial planning knowhow of the community, by encouraging the habit of saving and creation of community funds is essential to improve the current vulnerability of these populations.