A study to measure the full economic cost of bottom trawling in the EU, UK, Norway and Iceland shows that the fishing practice imposes up to €10.8 billion in annual costs to society, largely due to massive carbon dioxide (CO2) emissions from disturbed seafloor sediments.
Bottom trawling is a fishing method in which a net–some so large that they could hold ten 747 jets, the study said–is dragged along the seafloor to catch fish and other marine species, razing marine habitats and killing organisms along the way. Up to 75% of the marine life caught in the nets is bycatch–unintentionally caught animals that are considered not worth selling and therefore are just discarded.
The study, by UNESCO project Pristine Seas, finds that while bottom trawling supports jobs, provides protein and brings in revenue, the costs far exceed the benefits. Small scale fisheries generate between 3-4 times more jobs than industrial bottom trawlers, the report said. And bottom trawling fleets have the worst social and economic performance, considering 10 indicators (such as job creation, added value creation, profitability, or even overexploitation of resources, abrasion of the seabed, etc.).
“My biggest issue with trawling is not that it is in and of itself unsustainable, as it’s arguably capable of being managed far more sustainably than at present,” said Bally Philp, national coordinator of the Scottish Creel Fishermen’s Federation. “The issue arises in the all-too-common situation where trawling is taking place in locations where there’s alternative methods of fishing that can be more selective, support more employment and have a lower environmental impact. Because by allowing trawling to take place in those areas, we are essentially forfeiting jobs, revenues and our marine ecosystems unnecessarily, and I really cannot understand why we would allow trawling under those circumstances.”
European governments spend an estimated €1.3 billion annually on bottom trawling subsidies, a figure that the report said is nearly equivalent to the value of the jobs the industry creates. Without subsidies, bottom trawling in some countries would not even be profitable. Meanwhile, bottom trawling produces only about 2% of the animal protein that Europe consumes.
The European governments that offer the highest subsidies for bottom trawling are Italy, Norway, Denmark, Great Britain and Sweden. The total value of the marine life brought onto land via bottom trawling is highest in Norway, followed by Iceland, Great Britain, Italy, Spain, and the Netherlands.
Bottom Trawling’s CO2 Problem
The most measurable cost from trawling, however, is in CO2. Kat Millage, marine researcher for Pristine Seas and lead author on the study said bottom trawling imposes a net cost to European society of between €330 million and €11 billion annually, mostly due to the social costs of the enormous amount of CO2 that is emitted from disturbing the seafloor sediment.
One previous study in Nature found that the annual CO2 emissions released from bottom trawling are on the scale of the annual CO2 from global aviation. A second study in Frontiers in Marine Science added that over half of the CO2 produced underwater by bottom trawling will make it into the earth’s atmosphere within nine years.
The new study finds that permanently reducing bottom trawling efforts across Europe by a third would maximize net benefits under a scenario where a ton of carbon dioxide is valued at its minimum. Redirecting a fraction of current harmful subsidies would be enough to finance a fair transition for the fishing industry.
But the report notes other significant costs to society.
Trawling in MPAs
The report said bottom trawling in northern European Marine Protected Areas (MPAs) has caused vulnerable species such as sharks, rays and skates to be less abundant inside MPAs than in unprotected waters nearby. A coalition of civil society organizations has been calling on the governments of Europe and the UK to ban bottom trawling in the continent’s MPAs which are meant to be safe havens for marine life. Currently, the report said, 60% percent of European MPAs are bottom trawled, and 13% of the bottom trawling effort in Europe happens inside MPAs (20% for the EU).
“Bottom trawling in Europe is devastating marine life in more than half of the areas that are supposed to be protected by law. Bottom trawling in marine protected areas isn’t just an environmental aberration, it’s an economic failure,” said Enric Sala, National Geographic Explorer in Residence, founder of Pristine Seas, and one of the authors of the study. “Banning bottom trawling in MPAs would benefit ocean life, the climate, and even the fishing industry itself. It’s a win-win-win solution.”
To arrive at their findings, researchers analyzed bottom trawling efforts in European waters between 2016 and 2021 using data from Global Fishing Watch, which tracks real-time fishing activity worldwide using satellites. They then calculated the value of this fishing practice to European society as benefits (fishing revenue, protein supply, jobs) minus costs (operating costs, discards, subsidies and carbon emissions). One of the key measures authors used is the social cost of CO2 emissions, which provides an estimate of the economic damages stemming from the impacts of climate change, including sea level rise and declines in labor productivity and human health.
“Ending bottom trawling in Europe’s marine protected areas isn’t just good for the environment — it’s essential for saving billions in public costs,” said Sala. “This move will save taxpayers money, protect marine life, boost the fishing industry and help us tackle global warming.”
European leaders have already acknowledged the high cost of bottom trawling. In April 2024, Greek Prime Minister Mitsotakis announced his commitment to ban bottom trawling in Greek MPAs by 2030; Sweden followed two months later. The European commission’s action plan calls for gradually phasing out bottom fishing in all MPAs by 2030, in view of their key role in restoration of marine biodiversity and the importance of the seabed for healthy marine ecosystems and climate change mitigation.
“Bottom trawling is laying waste to the ocean life that provides jobs, food, and a liveable climate. As this research has confirmed, that is at a great cost to society,” remarked Hugo Tagholm, Executive Director of Oceana UK. “Small-scale, sustainable fishers are seeing their livelihoods ripped away along with the reefs and seagrass meadows that are bulldozed by the weighted nets. And all this to line the pockets of a few. The truth is that thriving marine wildlife supports flourishing coastal communities. That is why Oceana and our NGO allies are coming together for a Week of Ocean Action to urge governments in the UK and across the EU to ban bottom trawling in marine protected areas once and for all.”
