For less than 100 years ago, Sejerø Bay in northeastern Zealand was full of life. Eelgrass grew wild, while blue mussel beds and enormous stone reefs shaped the bay. Together, they supported large fish populations, and both seals and bluefin tuna were regular visitors. But decades of intensive stone fishing and bottom trawling, combined with nitrogen runoff from land, have destroyed habitats and dramatically reduced the number of fish in Sejerø Bay.

That nature is now set to be restored in what will become one of Denmark’s largest marine restoration projects. Over the next five years, eelgrass will be planted, half a million cod will be released, and up to six hectares of blue mussel beds and 6,000 cubic meters of stone reefs will be established in Sejerø Bay. All of this will support the restoration of the bay.

“It’s not many decades since Sejerø Bay was teeming with life. We want to bring that life back by restoring a number of important habitats, ecosystems, and fish populations that are in poor condition today. This will benefit both nature and the local community,” says Mikkel Aarø-Hansen, Secretary General of WWF Denmark.

Behind the project, Sejerø Seascape, is WWF Denmark along with a range of partners from universities, municipalities, and organizations. It is supported with a total of 33 million DKK from the Endangered Landscapes & Seascapes Programme (ELSP). The grant has been awarded to Sejerø Bay, which has been selected by ELSP as one of seven particularly significant restoration projects in Europe.

Local anchoring in the bay

Today, stone fishing and bottom trawling are banned in Sejerø Bay, and work is underway to reduce nitrogen runoff through Denmark’s green tripartite agreement. Parts of the bay have also been designated as Natura 2000 areas. Despite its degraded state, this means the bay still has the potential to recover, explains Line Gylling, Head of Nature in WWF Denmark.

“Several of our coastal waters are in very poor condition, and it will take time before life can return. But Sejerø Bay is still breathing, and that’s why we are now implementing ambitious restoration measures so the bay can become healthy again. There is still a need to improve and expand protection both in the bay and in surrounding waters, as well as reduce nutrient runoff from land.”
The project has strong support from the mayors of Odsherred and Kalundborg, the municipalities bordering Sejerø Bay.

“Sejerø Bay is a central part of Odsherred’s identity — both for nature and for the many citizens and visitors who enjoy our coastline each year. It is fantastic that we are now launching one of Denmark’s largest marine restoration projects. This strong collaboration will strengthen biodiversity, benefit the climate, and create a healthier bay for future generations,” says Karina Vincentz, Mayor of Odsherred Municipality.

“This is a fantastic project, and WWF Denmark has taken impressive leadership. The sea around us is a crucial part of our shared nature and identity. With Sejerø Seascape, we now have a historic opportunity to restore eelgrass meadows, stone reefs, and fish populations so life in the bay can flourish again — to the benefit of nature, our local communities, and the many visitors,” says Martin Damm (V), Mayor of Kalundborg Municipality.

By restoring the marine environment, we also create better conditions for outdoor recreation and tourism, allowing more people to experience the unique coastal nature we are fortunate to have in Kalundborg Municipality and around Sejerø Bay in general.

A science-based approach

Sejerø Seascape will be the first major restoration project in Denmark focusing on an open marine area. Researchers from DTU Aqua, the University of Southern Denmark, and Aarhus University will contribute with comprehensive studies and baseline assessments of the bay, forming the foundation for the ambitious restoration efforts that will unfold over the coming years.

“There is strong attention on marine restoration in Denmark. Sejerø Seascape must show how to conduct scientifically grounded marine restoration at scale, ensuring that nature reaps the greatest possible benefits in both the short and long term,” says Line Gylling.

At the same time, Sejerø Seascape will serve as inspiration for how collaboration between organizations, foundations, research institutions, local authorities, and communities can create real change for marine nature, explains Secretary General Mikkel Aarø-Hansen.

“We need large political initiatives and funding to restore nature on land and at sea, but we also need other types of collaboration if we are to bring nature back on track by 2030, which we are internationally committed to.”

About Sejerø Seascape

Sejerø Seascape – Nature Back to the Bay is one of Denmark’s largest marine restoration projects. It is led by WWF Denmark in collaboration with DTU Aqua, the University of Southern Denmark, Aarhus University, Odsherred Municipality, Kalundborg Municipality, and several local partners. The project is supported with 33 million DKK over five years from the Endangered Landscapes & Seascapes Programme, administered by the Cambridge Conservation Initiative in partnership with Arcadia.

The project will restore the bay’s marine environment by planting eelgrass meadows, rebuilding up to 6,000 m³ of stone reefs, establishing 4–6 hectares of blue mussel beds, and breeding and releasing 500,000 juvenile cod. All of this will improve the local marine environment and act as a catalyst for the restoration of the bay’s roughly 80,000 hectares.