Gravel beds in the North Sea need greater protection from bottom trawling by fishing vessels, researchers warn in a new study by the Institute of Natural Sciences.
Around 16% of the ocean floor is made up of such hard natural substrates, partly composed of matter ranging from gravel to pebbles, stones, and larger boulders.
These gravel beds are scattered across the predominantly sandy environment and host a unique fauna. A range of life forms such as soft corals, aquatic polyps, and branched bryozoans slowly grow there, forming complex three-dimensional structures. These areas also serve as oases for refuge, settling, and foraging.
The study examined the impact of commercial deep-sea fishing on these rocky North Sea reefs in two areas: the northwest and the Hinderbanken.
The northwest saw a spectacular increase in fishing activity between 2021 and 2022, with a 32% rise in the number of active vessels. About 86% of the area was disturbed.
In the Hinderbanken, the disturbed area was estimated at 89%. Although fishing activities decreased by 60% between 2021 and 2022, this area has faced chronic, intense fishing pressure for centuries, the Institute of Natural Sciences notes.
“The findings clearly illustrate that trawling can have harmful effects on the ecological functionality of these vulnerable habitats,” the study notes.
The researchers argue that the current protection given to these areas by various environmental management regimes is insufficient.
For instance, the Hinderbanken is a protected marine area, but “it is becoming clear that this legal status alone is not enough to achieve the desired level of protection,” the institute writes.
The findings of this study strongly advocate for appropriate regulation of disruptive fishing in the gravel beds, the researchers argue. They recommend implementing concrete management measures.
The study was conducted at the request of former North Sea Minister Vincent Van Quickenborne and the Marine Environment Service of the Federal Department of Health, Food Chain Safety and Environment.
Its findings will serve as advice during public tendering for the construction of offshore wind turbines.