CO2 release from bottom trawling disturbance and its relevance for seabed management

Bottom trawling is one of the most widespread anthropogenic disturbances to marine sediments and has the potential to transform long-term carbon sinks into sources of CO 2 release. The magnitude of resuspended organic matter remineralised into CO 2 remains poorly quantified and its relevance to marine management largely overlooked. In this study, we estimated CO 2 released to the water column from sediment disturbance by bottom trawling in the Hauraki Gulf Marine Park, using Global Fishing Watch effort data combined with regionally derived resuspension-induced CO 2 production rates and sediment characteristics. Estimates represent annual fluxes based on a steady-state assumption using sediment properties and CO 2 production rates derived from 2024 measurements. We also examined how these releases align with newly implemented conservation areas to evaluate the integration of sediment carbon into management frameworks. Our results indicate that bottom trawling releases an average of 519 tonnes of CO 2 per year into the water column in the Hauraki Gulf, equivalent to trawling activity releasing 0.64 t CO 2 km −2 yr −1 . Our findings highlight an overlooked carbon-cycling pathway associated with bottom trawling, whereby sediment disturbance generates CO 2 release into the water column. We suggest that considering the carbon-sink function of soft sediments in marine spatial planning and fisheries management could help identify areas where disturbance avoidance may provide ecosystem and carbon-storage benefits.