The ocean is under increasing pressure. Everyday human activities, from shipping to oil and gas exploration to urban pollution, are affecting the marine environment. Extensive research shows how this combination of stressors represents one of the greatest threats to marine wildlife, .
To protect the ocean, one of the primary tools we have is . But are they truly protecting species in the most critical locations?
In an attempt to answer this question in Brazil, we conducted a comprehensive study focusing on two key species: the , a nonmigratory species, and the , found in coastal and oceanic waters around the world. We chose these species because they do not migrate and stay in the same areas all year long, where they are exposed to harmful human activities.
The news is unfortunately not good: Our findings, , show that the areas critical for these species’ survival are also the most threatened.
Where whales and dolphins eat and play
Through spatial analysis, specifically , we uncovered these animals’ preferences. We cross-referenced thousands of occurrence records for Bryde’s whales and bottlenose dolphins with environmental data that can influence their presence. This included factors such as water temperature, depth and even food availability.
From this data, we created a map showing the most suitable habitats for these species. The results strongly indicated that southeastern Brazil is their “preferred area.” On the , these areas are located in shallower waters rich in nutrients, often associated with colder waters and steep seabed slopes that bring food to the surface.
The problem with overlap
The preferred areas we identified, however, are not exclusive to whales and dolphins. Southeastern Brazil is also an economically vital marine region for the country, driven by , where a new oil reserve was recently discovered.
In the second stage of our research, we overlaid our map of the most suitable habitats for these species with a map of human activity. This included the presence of ports, areas of oil and gas exploration, and various shipping routes.
The result is a near-perfect overlap. The areas where Bryde’s whales and bottlenose dolphins are most frequently found coincide exactly with where human activity is most intense.
Why protected areas aren’t helping them
Brazil has expanded its conservation coverage in recent years by , which we think is excellent news. However, the crux of the matter lies in the quality of that protection.
In 2024, we also participated in a global collaborative effort to evaluate marine protected area effectiveness, . The findings revealed that the vast majority of Brazil’s designated protected areas actually permit activities that are incompatible with biodiversity conservation.
This quality gap was also evident in our study. Most marine protected areas in southeastern Brazil, even the most effective ones, are coastal. They do not encompass the suitable habitats for Bryde’s whales and bottlenose dolphins, which are more heavily affected by oil and gas exploration.
And what about the oceanic protected areas Brazil created?
For the most part, they are located in areas that are either not the most suitable for these two species or lack significant conflicts with human activity. about whether governments are protecting the right places or leaving the most critical biodiversity hot spots and conflict zones unprotected.
The real impacts of the conflict
The risk of ship strikes is constant. Whales and dolphins must come to the surface to breathe, and in areas of heavy traffic such as southeastern Brazil, the risk of being hit by vessels is high. Meanwhile, constant noise – from both ship engines and oil and gas exploration – interferes with the navigation, communication and foraging of these animals.
Additionally, there is the risk of entanglement in fishing nets, particularly in areas with intense fishing activity, , the incidental capture of nontarget species. Finally, pollution from ports along with potential spills can degrade the health of these animals and weaken their immune systems.
A road map for the future
Our findings serve as a critical warning: Simply creating marine protected areas is not enough. They must be placed in the right locations, protecting species where they are most vulnerable. We have shown that there is an urgent need to rethink conservation strategies in Brazil.
In addition to strengthening the network of marine protected areas, our findings suggest the need for specific management actions to reduce conflicts. While , establishing and using can prevent dolphins from becoming entangled in nets.
Most importantly, however, we believe these actions must be applied in the areas of highest exposure for conservation to be truly effective. Protecting biodiversity while maintaining economic activity is a complex challenge, but we now have a map to begin this conversation.
This project was funded by the (Faperj), (Capes) and the (CNPq). We also acknowledge the support of the (ECoMAR-UFRJ), , , , , and . The publication of this article was also supported by .
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