Frequently Asked Questions on Bottom Trawling
Bottom trawling is considered to be one of the most destructive forms of fishing. It drags heavy, weighted nets across the seafloor, indiscriminately catching large quantities of fish and other species in its path.
Bottom trawling can be compared to bulldozing the ocean in the sense that it scoops up everything in its path, from fish and shrimps, to seagrass, sponges, and corals. Not only does bottom trawling often lead to overfishing, but it is also highly unselective, killing many non-target species (e.g. turtles) and juvenile ones (e.g. hake) too, so reducing marine biodiversity and disrupting ocean food webs. It can take marine habitats and ecosystems decades or centuries to recover from its impacts, if they do at all.
Bottom trawling also has a high carbon footprint, not only caused by the burning of fossil fuel to catch fish, but also as it can release carbon stored in seabed sediments back into the ocean, so undermining the ocean’s role in regulating our climate.
No, bottom trawling is not illegal in the EU. It is one of the most widespread industrial fishing methods, and highly lucrative in the short term. It provides approximately 30% of the total fish landed in the EU annually (in volume). Bottom trawling is allowed in many fishing areas, although it is banned or restricted in some sensitive zones, such as over certain deep-sea habitats and in specific marine protected areas.
Bottom trawling catches a wide range of seafood intentionally, including species that live on or near the sea bottom, such as cod, haddock, hake, sole, plaice, monkfish, Norway lobster and shrimp. However, by dragging huge nets along the seabed, it also unintentionally catches other marine animals and species that it was not targeting – known as bycatch – and resulting in vessels discarding catch back into the sea – around 90% in the case of trawlers in the EU.
Oceana campaigns to prevent bottom trawling from harming sensitive habitats and species. In this way, we advocate to prohibit it in EU marine protected areas – designated to protect specific marine species or habitats, in deep-sea areas where Vulnerable Marine Ecosystems occur, and in shallow coastal waters where we typically find blue carbon habitats like seagrass meadows.
Oceana also calls for a transition in Europe away from fuel-intensive, unselective and destructive fishing methods, like bottom trawling, towards low-impact, low-carbon practices.
Recovery after bottom trawling can range from a few years in muddy or sandy seabeds that are fast to recover, to several decades or centuries, if they recover at all, in the case of habitats with more complex physical structures, like cold-water coral reefs or sponge grounds.
For example, sandy seabeds may show signs of recovery within approximately 1–6 years, while deep-sea coral ecosystems – like the endangered Isidella elongata – can take several decades to a century or more to recover.
Yes, in most cases bottom trawling can be substituted with more sustainable gear. For example, Mediterranean hake can be caught using longlines and gillnets, and red mullet can be fished with trammel nets. More sustainable gear would help recover these species and reduce the damage caused to the ecosystem.
If properly managed, the use of gear, such as traps, purse seiners, long liners and gillnets, can improve species selectivity, reduce unwanted catches, and lessen the impacts on the ecosystem.
New bottom trawling technology such as pelagic doors, also known as ‘flying doors’ consist of large metal structures that keep the mouth of the net open while it is being towed through the water. Even if they can decrease the impact of trawlers on the seafloor by reducing the contact and the amount of resuspended sediments, the heavy net and other parts, accounting for over 90% of the gear, continue to drag over the seabed. So, even though they can be effective in reducing fuel consumption, they are an ineffective solution to avoid impacts on benthic habitats (those living on or near the seafloor).
Yes, for many years, the European Maritime and Fisheries Fund (EMFF) has been offering opportunities to the fishing sector to adapt their gears to more sustainable ones and to limit the impact of their activities on the marine environment. Improving selectivity and eliminating discards and bycatch has been a central pillar of the funding available from the EMFF.
All unprocessed fish sold in the EU – meaning fish sold fresh or frozen in supermarkets, at markets or at fishmongers – have to display on their labels the category of fishing gear that was used to catch them. This is not compulsory for processed seafood, such as canned, cooked or smoked products. But this requirement allows the consumer to make an informed choice, and as such, decide whether to buy the fish caught by a trawler, or not.
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