A new and pioneering study published in Frontiers in Marine Science estimates that around 50 per cent of the sediment carbon released as carbon dioxide by trawling and dredging activity will end up in the atmosphere. Independent scientists say this represents an urgent and important step forward in our understanding of the risks fishing activities pose to the security of ocean carbon stores.
An earlier paper by the same authors in 2021 famously estimated that trawling produced the same emissions of CO2 as the global aviation industry, but critics questioned whether any of this reached the atmosphere and therefore contributed towards climate change. The new paper, based on modelling, says it does.
The latest paper in Frontiers in Marine Science by Attwood et al says that regardless of the amount of CO2 remineralized underwater because of the trawling of the seafloor, over half of these CO2 emissions could flow into the atmosphere within a decade. And the CO2 that remains in the water will increase ocean acidification.
Blue Marine Foundation is supporting parallel studies into one of the great scientific questions of our time. Scientists are looking to quantify the amount of CO2 released by fishing disturbance with much needed empirical data from real-life sampling. To this end, Blue Marine has established the Convex Seascape Survey – a partnership with the University of Exeter and Convex Group Ltd – to carry out this important research.
By collecting reliable, robust data, from different parts of the world, and over several years, scientists involved in the survey intend to further quantify how much carbon the coastal ocean is storing, how much is being lost due to disturbance and how to help preserve and optimise the ocean’s role as the world’s largest carbon sink.
Callum Roberts, Professor of Marine Conservation at Exeter University and Chief Scientist of the Survey, said: “The Convex Seascape Survey was established to pursue robust, reliable data to complement and extend the trailblazing research of Attwood, Sala and their colleagues. The ocean’s carbon sink must urgently be brought into global efforts to mitigate climate change, and that means it must be understood far better. We will deliver high quality evidence on which decision makers can build new initiatives to draw down carbon emissions.”
Gabriella Gilkes, Programme Manager of the Survey at Blue Marine Foundation said: “To date, the Convex Seascape Survey has collected precise data across different gradients of seabed disturbance – from ‘no take zones’ to frequently trawled and dredged seabed, to accurately assess the different storage capacities of sediments, and the communities of animals that live on and in them.”
In April, in Plymouth Sound, UK, the survey will work with the commercial fishing fleet to follow trawling activity, and assess accurately and in real-time the amount of carbon that is being released into the water column and made available to exchange with the atmosphere from bottom-towed fishing gears.
What is now certain is that carbon dioxide lost from the ocean floor due to trawling activity reaches the atmosphere. It is expected to take several global studies to reach consensus on how much.