The gray dolphin, known scientifically as Sotalia guianensis, has been an emblem of maritime life in Rio de Janeiro for 130 years, prominently featured on the city's coat of arms. However, the current conditions in Sepetiba Bay, located 70 kilometers from downtown, reveal a stark contrast to its past as a serene sanctuary. Over the years, the waterway has been increasingly compromised due to human development, with the bay transforming from a nurturing environment for dolphins into a hazardous area filled with ships, fishing nets, and pollution.

Research from the Marine Ecology and Conservation Laboratory (ECoMAR-UFRJ) indicates that the dolphins are not merely coexisting with human encroachment but are being systematically confined and endangered. Over two decades of monitoring have documented significant declines in the gray dolphin population as they struggle against the impacts of urbanization. These factors have led to the loss of critical habitats that once supported their breeding and feeding.

The findings highlight the urgent need for conservation efforts to protect the gray dolphin population in Sepetiba Bay. Without intervention, the pressures from pollution and maritime traffic could lead to the species' decline, threatening not just the dolphins but also the ecological health of the bay itself. The situation underscores a vital intersection between urban development and wildlife conservation, raising critical questions about how best to balance human progress with the preservation of vulnerable species.