2025
Netherlands
TenneT is installing ‘fish hotels’ on offshore high-voltage stations (OHVS) to support biodiversity in the North Sea. The structures provide protection from marine predators and foraging areas for juvenile fish of species like cod, pouting, mackerel and pollack. Insights on the success of the fish hotels may be used to assess the feasibility and usefulness of installing fish hotels on other maritime structures. Initial observations show an increase in biodiversity around the OHVS using the fish hotels.
Highlights
01
The fish hotels are integrated into the design of the offshore high-voltage stations’ supporting jackets, reducing health and safety risks from installation.
02
The hotels are now a standard part of TenneT’s offshore high-voltage stations.
03
First ecological monitoring attempts have shown a general increase in biodiversity around the offshore stations using the fish hotels.
Main Information
The TSO TenneT (Netherlands) has launched a project aimed at supporting marine biodiversity by attaching ‘fish hotels’ to their offshore high-voltage stations in the North Sea. The fish hotels provide protection from marine predators and foraging opportunities for juvenile fish species like cod, pouting and pollack. The North Sea is considered to be in poor ecological condition due to pressure from overfishing, industrial activities, oil and gas extraction and shipping. Marine actors are therefore taking action to address their impacts and respond to the recently adopted EU Nature Restoration Law.
The hotels are attached to the jackets that support the stations before installation, reducing health and safety risks from installing them in the rough North Sea. The hotels are now a standard part of TenneT’s offshore high-voltage stations and now number nine, following the installation of two at the pilot site.
The project includes technical, ecological and monitoring knowledge. Monitoring activities began in summer 2025 and are ongoing. Specific results are unavailable so far but initial findings show an increase in biodiversity around the offshore high-voltage stations using the fish hotels. TenneT intends to share the findings publicly. The results may be scalable, providing insight into how fish hotels can integrate with other maritime structures.
