Study Finds Bottom Trawling Could Cost Europe up to €16bn a Year

Bottom trawling in European waters could be costing society up to €16bn a year, according to new research that attempts to quantify the wider economic and environmental impacts of one of the most controversial industrial fishing practices.

The study, highlighted by BusinessGreen and backed by National Geographic Pristine Seas, estimates that bottom trawling across EU, UK, Norwegian and Icelandic waters releases around 112 million metric tonnes of CO2 each year through fuel use and the disturbance of carbon-rich seabed sediments. It concludes that the annual costs to society could be up to 90 times greater than the €180m in profits generated by the sector.

Bottom trawling involves dragging heavy nets and gear across the seabed to catch species such as cod, sole, plaice, prawns and other bottom-dwelling marine life. The practice is economically important for parts of the European fishing fleet, but it has long been criticized for damaging seabed habitats, catching non-target species and disturbing marine ecosystems.

The new study broadens that debate by putting a monetary value on climate-related and social impacts that are often excluded from fisheries accounts.

Study Puts a Price on Hidden Environmental Costs

Researchers analysed more than 4,900 European-flagged bottom trawlers operating across the waters of the EU, UK, Norway and Iceland. Together, these vessels carry out more than 5.5 million fishing hours each year, according to summaries of the study.

The analysis compares benefits such as revenue, protein supply and employment with costs linked to fuel, labour, subsidies, discarded catch and CO2 emissions. The largest cost identified is the social cost of carbon emissions. This includes emissions from burning diesel and gasoline, as well as CO2 released when trawling gear disturbs seabed sediments that have stored carbon over long periods.

The study estimates a net annual social loss of between €2.25bn and €16.15bn, depending on the value assigned to each tonne of CO2 emitted.

The carbon accounting behind seabed disturbance remains an area of scientific debate. Some researchers and industry groups argue that uncertainty remains over how much disturbed carbon ultimately reaches the atmosphere, meaning the climate impact may be lower than some estimates suggest.

Even so, the study adds to a growing body of research suggesting that seabed carbon should be considered in climate and marine policy. A 2024 study estimated that bottom trawling globally could release hundreds of millions of tonnes of CO2 into the atmosphere each year.

Subsidies and Public Finance Under Pressure

The research also highlights the public finance dimension. European governments spend an estimated €1.17bn a year supporting bottom trawling, mainly through fuel-related subsidies and other forms of support.

The study argues that without these subsidies, bottom trawling would be unprofitable in some countries, including Belgium, Spain, Great Britain, Portugal and Romania.

For policymakers, this raises a practical question: whether public funds designed to support food security and coastal employment are also prolonging a high-impact fishing model. The study’s authors suggest redirecting part of this support towards less damaging fishing methods, fleet transition, monitoring technology and alternative livelihoods for affected fishers.

This would not be straightforward. Many coastal communities remain dependent on fishing income, and abrupt restrictions could create economic disruption for vessel owners, crew members, ports and processors. Any transition would need to combine environmental safeguards with targeted support for workers and regions most exposed to policy changes.

Marine Protected Areas Remain a Key Battleground

The findings are particularly relevant for marine protected areas. The study estimates that around 23 per cent of bottom trawling effort in the area analysed takes place inside marine protected areas.

In several countries, including Belgium, Bulgaria, France, Germany, the Netherlands, Romania and Spain, more than a quarter of annual trawling effort in exclusive economic zones is estimated to occur in such protected zones.

This overlaps with EU policy commitments. The European Commission’s Marine Action Plan calls for mobile bottom fishing to be phased out in marine protected areas by 2030, alongside measures to increase selectivity, protect sensitive species and support the fisheries sector through the transition.

Implementation remains politically difficult. Fishing groups have warned that restrictions could displace workers and reduce catches in coastal communities already facing volatile fuel costs, ageing fleets and changing market conditions.

Conservation groups argue that better-protected marine areas can improve long-term fish stocks, biodiversity and ecosystem resilience, including through spillover benefits to nearby fisheries. They also argue that protected areas lose credibility if damaging activities are allowed to continue within their boundaries.

Discarded Catch Adds to Ecological Concerns

Discarded catch is another major concern. The study estimates that up to 75% of marine life caught in bottom trawl nets may be discarded, although discard rates vary by fishery and have been reduced in some areas under EU rules.

The discarded catch has been valued at around €220m a year. Species affected can include juvenile fish, low-value fish, sharks, rays, skates and seabed organisms such as sponges, sea stars, corals and sea pens.

The ecological implications go beyond the immediate loss of marine life. Repeated seabed disturbance can alter habitats that support fish spawning, nursery grounds and wider food webs. Damage to slow-growing species and complex seabed structures can take years or decades to recover, depending on the habitat and intensity of fishing pressure.

For fisheries managers, this creates a tension between short-term catch value and long-term ecosystem productivity. If seabed habitats are degraded, the capacity of marine ecosystems to support healthy fish populations may also decline.

Implications for Seafood Supply Chains

The study also notes that bottom trawling provides only a small share of Europe’s food supply. It estimates that the practice supplies around 2% of animal protein consumed across Europe, while directly employing fewer than 20,000 people. By comparison, small-scale fisheries are estimated to generate about three times more jobs.

For companies and investors exposed to seafood supply chains, the findings point to rising regulatory and reputational risk. Retailers, food service companies and seafood processors may face growing pressure to verify catch methods, improve traceability and shift procurement towards lower-impact fisheries.

Banks and insurers with exposure to industrial fishing fleets may also need to assess fuel dependency, subsidy risk and future restrictions in protected waters. These risks are particularly relevant where vessels rely on public support, operate in areas facing tighter conservation rules, or use practices increasingly questioned by consumers and regulators.

Procurement policies may also need to account for the climate impact of seafood production methods. While seafood is often promoted as a lower-carbon protein compared with some land-based animal products, the climate profile varies significantly by species, gear type, fuel use and ecosystem impact.

A Climate and Biodiversity Policy Issue

For governments, the central issue is how to balance short-term economic disruption with long-term marine recovery and climate objectives. A managed transition would likely require targeted support for fishers, port communities and processors, as well as investment in more selective gear, vessel efficiency, spatial planning and monitoring systems.

The debate also connects to broader net-zero policy. Marine ecosystems store large amounts of carbon, and protecting them is increasingly seen as part of climate resilience and biodiversity strategy. Seagrass meadows, salt marshes, mangroves and seabed sediments all play roles in carbon storage, although the science around disturbance, release pathways and atmospheric impact varies by habitat.

The new research does not settle every question over seabed carbon, but it strengthens the case for treating bottom trawling as a climate, biodiversity and public finance issue rather than only a fisheries management issue.

As Europe works towards net-zero and 2030 biodiversity targets, the way it manages seabed disturbance and marine protected areas is likely to become an increasingly important part of the policy debate. The practical challenge will be to design policies that reduce environmental harm while giving affected fishing communities a credible route to adapt.

Source: www.businessgreen.com