Understanding the combined effects of ecological and economic factors on coral reef ecosystems

Coral reefs, though occupying only 2% of the ocean surface, are critical ecosystems hosting over 30% of global marine biodiversity. They provide vital ecosystem services, particularly for coastal populations relying on fisheries as a source of income and food security. However, these reefs are increasingly threatened by climate change, pollution, and overfishing, with pressures amplified by rapid population growth in coastal areas. This growth increases the demand for fish products, heightening exploitation pressures, particularly on reef ecosystems near urban centers, where local fisheries primarily serve nearby markets. Addressing these challenges needs integrated reef fishery management to ensure sustainable fishing practices and the resilience of exploited resources. For such management to be effective, it is essential to consider ecological, economic, and social factors that influence fishing dynamics, tailoring interventions to specific local conditions. Yet, there is limited research that combines these dimensions to assess spatial impacts on fisheries, especially in data-limited, small-scale reef fisheries. This study aims to analyze the influence of spatial characteristics on resource abundance, variability in fishing activity, and economic catch values. We applied a generalized mixed model to assess factors such as fishing area, local population density, and market access. Our focus is on the small-scale reef fishery in Ranobe Bay, southwest Madagascar, a Marine Protected Area (MPA) since 2015, but suffers of lack management. From 2020 to 2024, participatory monitoring was conducted across 12 villages surrounding the bay, data collection on catches, fishing effort, and the economic valuation of catches. GPS trackers were also fitted to fishing pirogues to map fishing zones accurately.The study revealed a clear north-south gradient in both catch volumes and fishing effort, with catch per unit effort (CPUE) significantly higher in the northern part of the bay, a finding linked to specific spatial characteristics. Despite this, an annual production decline between 10% and 20% was observed, accompanied by a rise in fishing incomes. This inverse trend suggests that fishers are compensating for declining resources by increasing their efforts, which risks accelerating stock depletion.Our findings highlight the critical role of integrating modern technologies, such as GPS tracking, with local community participation to generate spatially explicit data essential for localized resource management. This study illustrates how spatial data can enhance reef conservation efforts while addressing the economic needs of local communities. These insights support the development of integrated and adaptive marine spatial planning, helping to bolster coral reef resilience against the multiple pressures they currently face.