By Jeannette Bylov, AAU Communication and Public Affairs. Photo: Niels Madsen. Translated by Sinem Tunc, AAU Communication and Public Affairs.

Jammerbugt is undoubtedly one of the most sought-after fishing spots, especially for Dutch bottom trawlers. For several years, researchers, coastal fishermen, politicians, and conservationists have raised concerns about the negative effects on nature and coastal fishing in Jammerbugt.

During late summer and autumn, Professor of Marine Biology Niels Madsen led an interdisciplinary team of researchers from the Department of Chemistry and Bioscience, as well as the Department of Architecture and Media Technology, who followed in the wake of Dutch bottom trawlers fishing in the Jammerbugt area, stretching from Hanstholm to Hirtshals.

Seeking evidence of the extent of the damage

Using underwater drones, satellite tracking, and acoustic equipment, the research team has succeeded in demonstrating the adverse effects on the marine environment when heavy bottom trawls drag their nets across the seabed. The studies are supplemented with knowledge of benthic organisms through the collection of sediment samples and eDNA traces.

While it's not news for the research team that bottom trawling affects the seabed, the researchers have still been surprised by how distinct the traces left by the trawlers are.

- Our images show tracks resembling a plough dragged through a field. I hadn't expected it to be so evident," he says about mapping the seabed.

Causing harm to benthic organisms

According to the research leader, the problem lies in the fact that the heavy fishing gear disturbs the upper layers of the seabed and destroys the living conditions for many benthic organisms, altering the natural complex structure and chemical processes of the seabed.

The images taken with acoustic equipment and underwater drones also clearly show that bottom trawls fish in areas where there are stones and smaller stone reefs that are affected. 

- Most benthic organisms will be significantly affected. They cannot withstand the pressure from the chain mats dragged across the seabed, destroying their habitats," says Niels Madsen.

Niels Madsen also explains that some organisms may quickly recover as they have a short life cycle, perhaps only a couple of years. However, there is a risk that biodiversity will diminish, and organisms with longer life cycles, including rarer species, will be at risk of disappearing from the area over time.

New knowledge should ideally lead to action

Opdraget til forskerne har været at undersøge og skaffe dokumentation for fiskeriets påvirkning af havbunden.

- Once the evidence is accessible, I trust that the EU will ponder on whether it's still justifiable to permit fishing practices that have a substantial impact on the seabed and biodiversity, says Niels Madsen.