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Seaweed and shellfish farms: new vision to a regenerative future for coastal communities

Seaweed and shellfish farms: new vision to a regenerative future for coastal communities
Seaweed and shellfish farms: new vision to a regenerative future for coastal communities | Photo: Ben Wicks

The oceans are under strain. Centuries of overfishing, pollution and habitat destruction have reduced fish stocks and weakened marine ecosystems. Against this backdrop, a quiet revolution is emerging in the form of 3D ocean farming, a practice that cultivates seaweed and shellfish in vertical underwater gardens. This approach, which requires no feed, fertiliser or freshwater, offers a blueprint for regenerative food systems and healthier seas.

 

The concept was pioneered by the US non-profit GreenWave, founded by former fisherman Bren Smith. Its regenerative model rejects the extractive logic of industrial fishing in favour of polyculture systems that use the full depth of the water column. Seaweed ropes sway near the surface, mussels and scallops grow suspended below, while oyster cages rest on the seabed. Together, these species not only provide food but also filter pollutants, absorb carbon and create a habitat for marine life.


By design, such farms operate as a zero-input system. Shellfish filter nitrogen directly from the water, while seaweeds thrive on dissolved carbon dioxide, offering a rare example of food production that improves, rather than depletes, its environment. According to GreenWave, one hectare of ocean farm can yield as much protein as 50 hectares of wheat, without occupying land or competing with freshwater resources.


Wales’s first community-owned ocean farm

In the UK, the first large-scale attempt to adapt this model is unfolding off the Pembrokeshire coast. Câr-Y-Môr, meaning “For the Love of the Sea” in Welsh, is a community-owned enterprise that seeks to marry environmental restoration with local economic renewal.


The farm cultivates three species of native seaweed alongside mussels, oysters and scallops. Early estimates suggest a three-hectare site could produce around 15 tonnes of harvest annually, much of which can be channelled into food, fertiliser and bioplastics. Crucially, the project is not only about production. By involving local residents in farm operations and education, it aims to create jobs in sustainable aquaculture while fostering a deeper connection with the sea.


Wider context of British marine innovation

Câr-Y-Môr is part of a broader wave of interest in restorative aquaculture across the UK. A 2024 study by the Marine Biological Association and the University of Exeter found that seaweed and shellfish farms act as new habitats, boosting both abundance and diversity of coastal fish populations. Similarly, the Sussex Kelp Restoration Project is reintroducing kelp forests once devastated by trawling, with early signs of recovery in biodiversity and coastal protection.


These initiatives are attracting growing attention from policymakers, who see in them a chance to meet climate commitments and strengthen food security. Seaweed and shellfish farms absorb carbon, buffer coastlines, and increase biodiversity, positioning them as natural allies in the pursuit of the Sustainable Development Goal on life below water.

 

Câr-y-Môr

 

The promise of ocean farming is clear, yet its future depends on scaling up carefully. Supportive regulation, investment in local training, and research into new seaweed-based products will determine whether these community projects remain niche or expand into a significant industry.


For Wales, the experiment taking place off Pembrokeshire offers more than food. It suggests a model in which communities can be at the forefront of regenerating the seas they depend upon. If such initiatives grow, underwater gardens may one day become a familiar feature of Britain’s coasts, reminders that the ocean, when given space to recover, can feed both people and planet.


More information: https://www.carymor.wales/

 

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