By Fabricio C. Albuquerque, Guilherme O. Longo, Luiza S. Waechter, Mariana Bender, Filipe M. França

Fishing boats in the Porto beach, Baía Formosa in Northeastern Brazil, one of the municipalities surveyed in this study, where fishing families maintain strong socioecological ties to the ocean that shape livelihoods, diets, and cultural identity. Photo credit: Marcelly Madeiro.

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Coastal fisheries are a cornerstone of livelihoods, culture, and food security for millions of people worldwide. In Northeast Brazil, traditional fishing communities rely heavily on marine resources not only for income, but also as a primary source of animal-based food. At the same time, overfishing, habitat degradation, and climate change increasingly threaten tropical coastal ecosystems, raising concerns about how biodiversity loss may affect traditional populations’ nutrition and well-being.

We investigated how different animal-based foods contribute to the diets of traditional fishing communities on the Northeast coast of Brazil, with a particular focus on marine fish. Combining household food consumption data with detailed information on the composition of essential nutrients in animal-based foods (calcium, iron, selenium, zinc, and omega-3 fatty acids), we assessed dietary patterns of fishing families and evaluated how the potential loss of fish species, which multiple human impacts could cause, would affect nutrient supply. We found that marine fish are the main source of animal-based protein to these communities, accounting for around one-third of total animal protein consumed each month. Importantly, different fish species contribute to distinct combinations of micronutrients, meaning that fish diversity plays a central role in shaping nutritional outcomes. Our results show that marine fish can account for up to 70% of the essential nutrients available to fishing families, particularly for calcium, selenium, and omega-3 fatty acids, which are critical for child growth, immune function, and cardiovascular health.

Using simulated scenarios of species loss, we found that losing even a quarter of local fish species could lead to reductions of more than 70% in essential nutrients supply. This highlights how vulnerable coastal communities may be to biodiversity loss, even if total fish consumption remains high. Our findings suggest that fisheries management and conservation policies could better support human well-being by explicitly considering species’ nutritional quality. Incorporating nutritional value into fisheries governance — alongside traditional measures such as catch and biomass — can help protect species and ecosystems that are especially important for food and nutrition security, strengthening the links between people and nature in coastal social–ecological systems.