Repurposed smart tuna-fishing buoys provide real-time ocean intelligence for ecological and blue economy applications

Repurposed echosounder buoys developed for industrial tuna fishing are emerging as powerful ecological monitoring tools, providing real-time biomass data across marine habitats. We present a novel field concept study applying this cross-sector innovation, by using smart-buoys to track the biomass of critical habitats, detect potential fishing impacts, and support biodiversity accountability within the blue economy. Repurposed through the Satlink project ReCon, smart-buoys measure vertical biomass distribution and transmit continuous data streams via satellite (INMARSAT) to shore-based systems. Our deployments lasted 72–170 h in both fixed-point station and drifting configurations, covering one shelf area, two coral reefs, and two seamounts/pinnacles in the Western Indian Ocean (WIO) region (Bazaruto Archipelago, Mozambique), yielding > 1,000 hourly total biomass records. Integration with the Benguerra Island-based BCSS Ocean Observatory provided simultaneous weather and oceanographic baselines for over 20 in-situ variables, while concurrent scuba verification surveys recorded 14–20 megafauna taxa per site. The resulting datasets revealed diel cycles with 20–40% higher nocturnal biomass, coinciding with cooler bottom waters and transient chlorophyll-a pulses, and illustrated how site-level heterogeneity challenges broad ecosystem status labels, such as an overfished reef displaying higher evenness and diversity than a nominally healthy reef. This demonstration highlights a real-time scalable monitoring platform that bridges fisheries technology and ecology, providing a novel class of verification tools for MPAs, fisheries management, biodiversity crediting, and ESG-aligned interventions. Crucially, by providing continuous and verifiable ecological indicators, it addresses a fundamental supply/demand-side barrier for blue finance and biodiversity markets: investor confidence, accountability, and trust in real-time outcomes.