A study has challenged the often-stated contention of the fishing industry that it has one of the lowest carbon footprints of any form of food production.
The first study to look into the climate change impact of bottom trawling, a damaging fishing method used worldwide that drags heavy nets across the ocean floor, has found that its global emissions are equivalent to those from the entire global aviation sector.
Previous studies have looked at the emissions from the fuel burnt, not the carbon stirred into the water column or the damage trawling causes to plants and animals on the seabed that can soak up carbon.
The study by 26 scientists published in Nature finds that the amount of carbon dioxide released into the ocean from the practice of trawling is larger than most countries’ annual carbon emissions – and the UK is one of the top ten countries in whose waters the damage is being caused, with others being China, Russia and Italy.
Dr Trisha Atwood of Utah State University, a co-author of the paper, said: “The ocean floor is the world’s largest carbon storehouse. If we’re to succeed in stopping global warming, we must leave the carbon-rich seabed undisturbed. Yet every day, we are trawling the seafloor, depleting its biodiversity and mobilizing millennia-old carbon and thus exacerbating climate change.
“Our findings about the climate impacts of bottom trawling will make the activities on the ocean’s seabed hard to ignore in climate plans going forward.”
The study finds that countries with the highest potential to contribute to climate change mitigation via protection of carbon stocks are those with large national waters and large industrial bottom trawl fisheries. It calculates that eliminating 90 per cent of the present risk of carbon disturbance due to bottom trawling would require protecting only about 4 per cent of the ocean, mostly within national waters.
Dr Enric Sala, explorer in residence at the National Geographic Society and lead author of the study, Protecting the global ocean for biodiversity, food and climate said: “Ocean life has been declining worldwide because of overfishing, habitat destruction and climate change. Yet only 7 per cent of the ocean is currently under some kind of protection.”
“In this study, we’ve pioneered a new way to identify the places that—if strongly protected—will boost food production and safeguard marine life, all while reducing carbon emissions,” Dr Sala said.
“It’s clear that humanity and the economy will benefit from a healthier ocean. And we can realize those benefits quickly if countries work together to protect at least 30 per cent of the ocean by 2030.”