Repurposed smart tuna-fishing buoys provide real-time intelligence for marine conservation and ocean observation

End-of-use echosounder buoys developed for industrial tuna fishing offer a largely untapped opportunity to expand ocean monitoring using existing fisheries technology. Here we present a technology-transfer and pilot feasibility study testing whether repurposed smart-buoys can operate as short-term autonomous platforms for marine conservation monitoring and ocean observation. Through Satlink project ReCon, refurbished buoys were deployed in fixed-point and drifting configurations across one shelf technical test area, two coral reefs, and two seamount/pinnacle systems in the Western Indian Ocean (WIO) region (Bazaruto Archipelago, Mozambique). Fixed-point acoustic record spans ranged from 51.5 to 96.2 h per site. Across fixed-point and drifting configurations, the exported dataset contained 393 time-stamped acoustic records and 1,281 depth-layer relative acoustic biomass/backscatter observations, with buoy position and acoustic data transmitted by satellite (via INMARSAT) to shore-based systems. Integration with the long-term BCSS Ocean Observatory time-series provided concurrent weather and oceanographic context across > 20 in-situ variables, while scuba-based megafauna surveys recorded 14–20 megafauna taxa per site as biological context for the acoustic records. The pilot time-series captured consistent diel structure, with 20–40% higher nocturnal relative acoustic biomass/backscatter values, alongside exploratory temporal co-occurrences with cooler bottom-water pulses, transient chlorophyll-a increases, and site-level differences in megafauna assemblage structure. While these short time-series cannot be used to infer ecological baselines, reef health, fishing impacts, environmental drivers, or absolute biological biomass, they demonstrate the capacity of repurposed smart-buoys to generate high-frequency acoustic and contextual ecological information in data-poor and remote marine regions. Our study establishes a practical pathway for integrating recovered fishing infrastructure into marine observatories, while highlighting the need for longer deployments, broader replication, quantitative habitat characterization, and independent biological calibration before robust ecological inference can be made.