SUMMARY The surprise discovery of cold-water soft corals sparked an ambitious seafloor habitat-mapping project that drove Denmark to propose a ban on seafloor habitat destructive fishery with beam, a form of bottom trawling.
THE DISCOVERY On a research mission in Denmark’s northwestern coast, explorer and environmental scientist Klaus Thymann dove into the rough cold sea of the Jammer Bay to investigate bottom trawling impacts on the seafloor. There, Thymann was shocked to discover an abundance of cold-water soft coral and other marine life thriving in an area officially classified mainly as sand.
This unique discovery kicked off an ambitious multidisciplinary mapping project in collaboration between the Technical University of Denmark (DTU) Aqua Klaus Thymann and included a citizen science project of seafloor mapping. The project wrapped in May 2025 and created a chain reaction that led the Danish government to act on harmful bottom-trawling.
“Without maps we cannot navigate — it was true for seafarers and remains true for charting a future for the oceans. We need maps, data and knowledge more than ever.” – Klaus Thymann, Explorer & Scientist
COMMUNITY SCIENCE Denmark has more coastline than France, but little is known about the ocean floor just off its shores.
The cost and logistics required for seafloor research is often prohibitive for environmental study- which is why we have better maps of the surface of the moon than the ocean floor.
Klaus Thymann aimed to change that by inventing and building a simple, lightweight drop‐camera that local fishermen could easily deploy. The units were dropped in more than 120 spots resulting in a detailed understanding of the sea-floor habitat in the surveyed area. The local fishers had a personal stake in the effort. Their sustainable fishing methods were being undercut by the destructive the beam-trawlers, leaving the fish and their livelihood depleted.
“When I see the pictures from the bottom, it’s not how I thought it would be. It’s a different world to see it in real life. We have to protect the environment.” – Jesper Olsen, Thorup Strand Fisher
A RICH HABITAT DTU Aqua layered five years of fishing vessel-tracking (AIS and VMS) over the drop camera maps and found that many of the coral areas were getting hit repeatedly by beam trawlers. Some soft coral sites saw more than ten passes a year. Drop-camera footage even showed fragile soft corals just meters away from busy trawl lanes—details we’d never had before. These eye-opening results revealed this species to be far more abundant in the Jammer Bay than hitherto documented. The Soft Corals live attached to hard faces of cobbles and boulders and are highly sensitive to heavy fishing gears, such as beam bottom trawls, that can operate on rough substrate. Drop camera maps are useful and inform nature protection alongside traditional sonar-based habitat mapping and can show exactly where bottom-trawling overlaps the most sensitive habitats and making the case for an urgent ban on bottom trawling fishing.
PROTECTING THE SEAFLOOR Concerns of trawling impacts on seafloor habitats in the Jammer Bay led to a multi-disciplinary project, JAMBAY, funded by The European Maritime and Fisheries Fund (EMFF) and The Danish Fisheries Agency in 2023. The primary goals of this DTU Aqua led project were to map the marine habitats and to investigate the fisheries’ impacts on the seafloor of the Jammer Bay and Skagerrak. The habitat mapping was conducted by the project partner, the Geological Survey of Denmark and Greenland (GEUS), and using state-of-the-art methods developed for nature conservation-based marine habitat mapping. GEUS created a detailed, 5-meter resolution map exceeding 300 km2, by far the largest coherent seafloor habitat map ever made in Denmark for ecosystem-based management purposes. The fisheries impact studies applied new high-resolution models, water tank experiments, and experimental sea trials in the Jammer Bay.
With conclusive results in hand from the EMFF-JAMBAY project, the Danish government has approached the European Union to propose a ban of all fishery with beam trawls in Jammer Bay and the wider Skagerrak.
Such a ban of bottom trawling with beam will be a massive win for seafloor habitat protection and for the local fishing community that use traditional low impact fishing methods – and of course for the flora and fauna, including fish and soft corals that inhabit this part of the Danish waters.
The project was supported by the Velux Foundation and the Lighthouse Foundation.