Artificial stone reefs play an important role in restoring biodiversity in Danish waters. However, their impact depends on more than simply placing stones on the seabed. Location, current conditions, depth, and oxygen levels are crucial parameters if the reefs are to create the greatest possible value for the marine environment.
At Høj Nordic Marine Contractor, we combine technical expertise with a deep understanding of marine ecosystems. We have established stone reefs in several projects focused on restoring variation to the seabed and strengthening the sea’s natural balance.
In Naturpark Lillebælt, we have contributed to the “Bælt i Balance” project, where new stone reefs improve habitats for species such as cod, sea trout, and harbour porpoises.
Near Aarhus, we deployed 1,500 tonnes of stone to establish new reefs, and in the German part of the Baltic Sea, we used the vessel Aase Høj to restore stone reefs with high precision -even under challenging conditions and close to critical infrastructure.
As the seabed gains new structure, marine life gradually returns. Seaweed and algae take hold and contribute to oxygen production, while mussels, sea squirts, and sponges establish themselves on the stones. Small marine organisms find shelter in cracks and crevices, and over time a rich food source develops.
This attracts small fish seeking both food and protection – followed by larger predatory fish. The stone reefs function as natural “nurseries” for fish, where juvenile fish enjoy improved survival conditions that benefit overall fish populations.
Across all projects, one conclusion stands clear: when we restore variation to the seabed, life returns.
Stone by stone.
