The big questions “Ocean with David Attenborough” raises about bottom trawling – and what the evidence says
Released ahead of World Ocean Day on 8 June, Sir David Attenborough’s new documentary, Ocean, once again brings vital attention to the health of our seas and the complex role that fishing plays in shaping marine ecosystems.
While the documentary’s intentions are clearly rooted in a desire to protect the ocean and it sends a strong message of hope, the portrayal of fishing - particularly bottom trawling and dredging - would benefit from additional context and balance. The documentary offers limited focus on important advances in sustainable fisheries management and fishing practices, and on other major human activities that also impact marine environments.
Nevertheless, Ocean raises vital questions about where and how certain fishing methods are used - questions that are now being actively explored by the public, media and policymakers alike.
At Seafish, we believe seafood is the way forward. We’re committed to supporting a sustainable seafood industry grounded in sound science and evidence. In this blog, we respond to seven key questions raised by Ocean, offering science-based insights into UK fishing practices to help inform the conversation.
- How important are our oceans to feeding a growing population?
- What is bottom trawling and how important is it to the UK seafood sector?
- What is the impact of bottom trawling in UK waters?
- What are Marine Protected Areas and what is their purpose?
- How do we monitor and manage bottom trawl fisheries?
- Can bottom trawling ever be compatible with MPAs?
- What is already being done to minimise the impact of bottom trawling on the seabed?
A downloadable version of this article, as well as a summary, can be found at the bottom of this page.
Oceans cover 70% of the Earth and are vital as a source of food, for climate regulation, carbon absorption, biodiversity and the global economy - supporting 600 million livelihoods and 100 million jobs across the world. Seafood is a key protein source for billions, with bottom trawling playing a major role in supplying this food at scale.
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According to the UN Food and Agriculture Organization (FAO), around one billion people worldwide rely on fish and shellfish as their main source of animal protein. 3.2 billion depend on aquatic foods, including from wild caught seafood and aquaculture, for at least 20% of their daily protein intake. A significant portion of this fish is caught using bottom trawling methods, so it is regarded as essential to ensuring a consistent and large-scale supply of seafood to a growing global population. Seafood plays an important role in contributing to key UN Sustainable Development Goals.
2. What is bottom trawling and how important is it to the UK seafood sector?
Commercial fishing methods in UK waters are diverse. They include bottom trawling, where nets or dredges are towed along the seabed, midwater (pelagic) trawling, pots and traps, and hook and line catch. In the UK, bottom trawling is regulated within a wider fisheries management system to minimise its impact on fish stocks and marine ecosystems. More than a quarter of the UK’s overall catch, including species like cod, haddock, langoustine and scallops, is bottom trawled. It’s therefore economically important to the UK seafood industry and the wider economy, and provides some of consumers’ favourite seafood species. Here in the UK, we import the majority of the seafood we eat and export the majority we catch. We therefore acknowledge the vital importance of responsible stewardship of UK and overseas fisheries, effective management of the high seas, and to tackling illegal, unreported and unregulated fishing (IUU) as part of international supply chains.
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Bottom trawling refers to a commercial fishing method where nets or dredges are towed along or on top of the seabed to catch species that live on or near it— known as demersal species. These include some of the UK’s most popular seafood, such as cod, haddock, langoustine (scampi), plaice, lemon sole and scallops. These species are economically important to the UK seafood industry, highly valued by consumers and contribute to our food security.
According to the Marine Management Organisation (MMO) 27% of all catches from UK seas in 2023 were bottom trawled (valued at £275.1 million), making it a significant contributor to the UK’s wild-caught seafood supply. The remaining 73% came from various methods. Midwater (pelagic) trawling, which targets midwater species such as mackerel and herring, accounted for 31%. This fishing method does not come into contact with the seabed. Other methods include pots and traps and hook and line catch accounted for 42%.
This highlights that bottom trawling is an important part of the UK’s diverse seafood sector. As an island nation, the UK has a long-standing tradition of trawl fisheries which have supported coastal communities for generations. This heritage is reflected in the enduring popularity of dishes like fish and chips, typically consisting of trawl-caught cod or haddock.
In the UK, bottom trawling is managed as part of a broader fisheries management framework to ensure that impacts on fish stocks and marine ecosystems are avoided, mitigated or remedied where necessary. This can include the use of temporary, seasonal or permanent closures of sea areas to fishing if there are concerns about marine conservation.
As an island nation, the UK has a long-standing tradition of trawl fisheries which have supported coastal communities for generations. This heritage is reflected in the enduring popularity of dishes like fish and chips, typically consisting of trawl-caught cod or haddock. Fishing around the UK largely takes place on key grounds which have been fished for generations. Fishing activity is monitored, and maps showing where fishing is taking place can be found through resources like Global Fishing Watch. These show that fishing is concentrated on specific areas and that not all parts of our seas are fished.
3. What is the impact of bottom trawling in UK waters?
While bottom trawling involves contact with the seabed, it’s strictly regulated in the UK. It’s also one of the lowest environmental impact forms of animal-based food production because it has a very low carbon footprint, does not require inputs of feed or fertiliser and has increasingly robust science to support its management.
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All forms of food production have an associated environmental impact. The key is to understand, manage and minimise the associated impacts as much as we can. Wild capture fishing, including bottom trawling, remains one of the lowest environmental impact forms of food protein production.
The impact of bottom trawling is influenced by:
- The type of fishing gear that’s used.
- The intensity of fishing, for example, how often an area of seabed is trawled per year.
- The biodiversity, sensitivity and recovery rate of the habitats being trawled - these elements are highly variable, so it is not possible to classify all bottom towed gears, in all fisheries, on all seabed types as inherently ‘high-impact’.
The International Council for the Exploration of the Sea (ICES) publishes independent assessments of the impact of bottom trawling on seabed (benthic) habitats. The most recent assessments published in December 2024 show that for seas around the UK, fishing with bottom towed gears is largely restricted to key fishing areas, with the vast majority of our seas showing a low, and in some cases decreasing, impact from bottom trawling.
ICES’ assessments state:
- For the North Sea area:“Fisheries impacts on benthic habitats have been declining on average since 2019.”
- For the West of Scotland and Celtic Seas: “Mobile bottom-contacting gears are concentrated on the Nephrops grounds, along the continental shelf edge, and throughout the Celtic Sea. There is little activity by mobile bottom-contacting gears in much of the area west of Scotland.”
4. What are Marine Protected Areas and what is their purpose?
Marine Protected Areas (MPAs) are areas of sea around the world which are designated to protect a specific marine habitat, feature or species. MPAs cover much of the UK’s territorial waters. Each UK nation is responsible for designating MPAs in its surrounding waters. There are 377 MPAs in UK waters covering over 338,000km2 of sea area. This equates to almost 40% of the waters under UK control (known as our ‘Exclusive Economic Zone’) and is greater than the entire land mass of the UK (243,000km2).
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Our MPA network reflects the biodiversity of UK seas. Some MPAs protect seabed features like horse mussels and flame shells while others are designated to protect animal species such as basking sharks, whales, dolphins and seabirds. Some sites have been created to protect geological features such as subsea canyons and seamounts. MPAs, and their management, are routinely reviewed by regulators to make sure that they remain fit for purpose and continue to deliver marine conservation benefits.
- Marine Protected Area (MPA) is the umbrella term for areas designated to protect specific marine ecosystems, habitats, species and subsea features.
- Marine Conservation Zones (MCZs) are a specific type of MPA, created under the Marine and Coastal Access Act 2009. They aim to protect nationally important, rare, or threatened marine habitats and species. There are 91 MCZs in waters around England.
Other types of MPA in the UK include:
- Special Areas of Conservation (SACs) designated under the EU Habitats Directive.
- Special Protection Areas (SPAs) designated under the EU Birds Directive.
- Highly Protected Marine Areas (HPMAs) a newer designation offering stricter protection.
5. How do we monitor and manage bottom trawl fisheries?
Monitoring of bottom trawling in UK waters is very robust. UK vessels are not allowed to trawl in areas where the seabed has been identified as vulnerable or ecologically sensitive. These restrictions are backed by stringent regulations and active enforcement. There are high levels of compliance across the fleet. In 2025, the first ever prosecution for breaches of bottom trawling rules was secured. This involved a non-UK vessel bottom trawling in a UK MPA.
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Technology innovation is increasingly being developed and used to monitor wild capture fishing, and support the delivery of more sustainable practices, including:
- Catch methods: reducing seabed impact and bycatch with selective gear.
- Data and stock management: using tech like AI for automated catch reporting.
- Monitoring: designing systems to improve compliance with fishing rules.
- Gear recovery: improving ways to track, retrieve and recycle lost gear.
Enforcement measures are in place to monitor fishing activity and ensure regulations aren’t breached. In the UK, fishing vessels over 12m in length must be fitted with a Vessel Monitoring System (VMS) which tracks where it goes, primarily to ensure compliance with fishing regulations. Similar tracking technology is being rolled out for inshore vessels under 12m which typically include day-trip fishing operations. Some vessels are also fitted with CCTV cameras, known as Remote Electronic Monitoring (REM), to monitor catches and bycatch.
With these technologies and monitoring systems, rule breaking by vessels fishing in MPAs is thankfully very rare. This demonstrates the high level of compliance by UK vessels. In May 2025, the first ever prosecution of a vessel for fishing in an MPA in UK waters was secured. It involved a French trawler found to have illegally used bottom towed gears in the Offshore Brighton Marine Conservation Zone. The skipper was fined £40,000. Prosecutions like this show how seriously regulators take offences and how effective enforcement helps support marine conservation.
6.Can bottom trawling ever be compatible with MPAs?
Some MPAs rightly have restrictions on bottom trawling activities. These rules are well understood and respected by the UK fleet. Bottom trawling is compatible with some MPAs, where it doesn’t significantly harm the species, habitats or features being protected. MPA management should be tailored to each site’s conservation goals, avoiding unnecessary bans on activities that aren’t harmful. A blanket ban on bottom trawling would not always support conservation and could harm coastal communities that rely on fishing.
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Protecting marine biodiversity is important to people and the planet, not least to the fishermen who depend on healthy and productive seas for their livelihoods, support their rural and coastal communities around the UK and help meet consumer demand for seafood.
Many MPAs which do aim to protect features vulnerable to bottom trawling – such as reef-forming marl, horse mussels or flame shells – already have restrictions in place which control the fishing activity that can or cannot take place.
For example, the Scottish MPA network already has restrictions on fishing activities in MPAs where these vulnerable species or features are known to exist. These rules were introduced in 2016 and include a mix of outright bans on bottom trawling, restrictions on certain types of fishing gear and seasonal closures.
More recently, the UK has been exploring the use of Highly Protected Marine Areas (HPMAs). These ban not just fishing but the removal of anything from an area of sea to protect all species and habitats in the site. The first three HPMA sites were designated in English waters in 2023.
However, many of the species, habitats and features protected by MPAs aren’t directly affected by bottom trawling. Since not all protected features in MPAs are harmed by it, this type of fishing can be fully compatible with some MPA conservation goals.
By tailoring management of each MPA to the species and features we want to protect, we can make sure that they protect biodiversity but don’t unnecessarily ban or exclude activities that are not considered harmful. For example, while it might be appropriate to have ‘no-anchoring zones’ for leisure boats in some areas to protect seagrass beds, that does not mean anchoring should be banned in every MPA. Similarly, banning bottom trawling would not necessary be helpful in sites designated to protect whales or dolphins, as these species are unlikely to be directly impacted by bottom trawling.
Therefore, banning bottom trawling in all MPAs would not necessarily help meet conservation goals, although it would have a negative impact on the fishermen and coastal communities which might depend on commercial fishing in these areas.
More information on the UK MPA network, including guides to how they are managed and where fishing is restricted, is available in the Seafish guide to Marine Protected Areas.
7. What is already being done to minimise the impact of bottom trawling on the seabed?
The UK fishing industry is continually seeking to become more sustainable, innovating in partnership with scientists, gear designers and policymakers. Even in seabed areas where bottom trawling is permitted, innovative work is underway to develop new technologies and techniques, especially in fishing gear, that help minimise its impact and improve vessels’ efficiency.
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Fishing gear innovation to reduce habitat impacts is increasingly important to the UK’s fishing industry and the wider seafood supply chain. The fishing industry is used to a changing operating environment and continues to adapt and evolve. Nowhere is this more evident than in developments in fishing gear.
Traditionally, fishing gear was designed with the sole aim of maximising catch rates. Today, innovation in selective gear technology is central to more sustainable fishing practices. One of the main focuses of gear technology and innovation - by the fishing industry, research community, governments, regulators and gear designers - is to reduce seabed impact. Over many years, and supported by Seafish, the UK fishing industry has collaborated in research and development to advance innovation in fishing gear technology.
Recent examples of UK gear innovation include:
- The Sumwing beam trials to help reduce seabed impact, reduce discards and reduce fuel consumption
- The Smartrawl project which uses AI to address the issues of bycatch and discards
- A scallop gear innovation project to reduce seabed impacts while maintaining catch efficiency
- Nets of Tomorrow - A Collaborative Effort to Sustain Fisheries and Marine Life
Reducing seabed impact not only helps improve sustainability but also benefits fishermen themselves. Less contact between the gear and the seabed means lower drag, lower fuel use, less wear and tear on and the potential loss of fishing gear at sea. This means it is in everyone’s interest to reduce seabed impact.
Over many years, the UK fishing industry has been engaged in research, development and training at the Hirtshals flume tank in Denmark. Work has involved net manufacturers, gear trial specialists, fishing companies and the wider seafood supply chain. The state-of-the-art facility has enabled testing of the operational characteristics of different bottom trawl and trawl door innovations and configurations, designed to reduce benthic impacts.
Training on fishing methods used in UK waters, including innovations to reduce the impacts of bottom trawling, is delivered annually to the four UK nations’ policymakers and regulators, as well as to the wider seafood sector.
Work is underway in the UK to identify potential steps to improve the regulatory framework, to better enable modified and new selective gears to be trialled and, where successful, commercialised. The four UK nations are also currently reviewing draft new Fisheries Management Plans (FMPs) and catching policies. These are being developed collaboratively with industry stakeholders and other partners, drawing on best available science, the practical knowledge of fishermen and established policy objectives under the 2020 Fisheries Act. The goal is to implement the most sustainable measures for managing fisheries — tailored by stock, fishery and location.
Collectively, these initiatives are helping to ensure the UK remains at the forefront of progress on sustainable seafood production as part of the blue economy. But this work is ongoing: further collaboration will help drive other innovation and improvements in bottom trawling practices, where the fishing industry and wider seafood sector are central to the solutions.
Further information
- More resources and case studies can be found in the Seafish Fishing Gear Database
- In the UK, MPAs are designated by each administration and more information on site selection, features being protected, and restrictions on fishing can be found through Defra, Nature Scot, DAERA, and Nature Resources Wales.
- Overview: Selective gear technology for fishing
- In Brief to The State of World Fisheries and Aquaculture 2024
- JNCC – Advisor to Government on Nature Conservation
- ICES ecoregions and advisory areas
A summarised version of this article is available to download via the link below. The full blog is also available to download.