The global decline of marine biodiversity due to human-related pressures, especially pollution, climate change, and overfishing, is our time’s critical emergency. To identify interventions that can reduce human impacts and successfully slow or reverse this decline, we need to map and monitor the spatial distribution of biodiversity at sea. Hence effective management requires large-scale monitoring, easily accessible and integrated data, and decision-support tools. Currently, our approaches to monitoring and assessing marine biodiversity remain inefficient, complex, and expensive. SEAWATCH aims to explore a promising but potentially transformative direction: using fishing vessels as sentinels of marine biodiversity and the impacts it is facing. The idea is to combine the collection of environmental DNA (eDNA), carried out through new-generation passive probes, with satellite data and models based on artificial intelligence (AI).