Denmark’s marine gardens thrive as sustainable food sources and biodiversity enhancers

Henrik Sidelmann Christensen inspects various sock-like nets immersed in water, searching for the one with the ideal weight. Finally, he retrieves a two-meter-long sock filled with large blue mussels. The communal dinner at Bælthaven in Middelfart is ready.

Mussels are cultivated in long socks submerged in the water, with each sock weighing about 20 kilograms, providing enough mussels for 30 to 40 people. Bælthaven is part of a growing movement of marine gardens across Denmark, with nearly 50 currently in operation—a significant increase from just one 15 years ago. This concept has also spread to countries like Norway and Sweden, inspired by Danish practices.

According to Joachim Hjerl, founder of the interest organization Havhøst, these marine gardens contribute positively to the marine environment. Mussels and seaweed cultivated in these gardens filter seawater and absorb harmful nutrients, effectively transforming pollution into food. Marine biologist Cecilie Petersen notes that the presence of these gardens can visibly improve water clarity and increase biodiversity.

The first marine garden, Havhaven Ebletoft Vig, was established in Ebeltoft in 2011. Typically community-based, these gardens range from 20 to hundreds of members and have expanded beyond Denmark’s borders. They primarily grow seaweed, blue mussels, and oysters.

Mussels have a minimal climate impact, emitting the same amount of CO2 as white cabbage per kilogram. Hjerl emphasizes that these marine gardens exemplify sustainable food production that nurtures ecosystems rather than depleting them. At Bælthaven, with about 200 members, last year’s yield provided several tons of mussels for community meals. As chairman Erik Yde points out, supporting sustainable food practices is crucial for the planet’s future.