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SIFT Project

Seaweed Cultivation

There is growing interest in seaweed cultivation around the coasts of Scotland. Cultivated seaweed can be used for a variety of purposes, including human consumption, animal feed, biofuel, fertiliser, cosmetics and pharmaceuticals.

Since November 2018, applications have been submitted to grow and harvest seaweed in an area covering more than 2 million square metres of the Scottish marine area and the sector is expected to continue growing.

What is seaweed cultivation?

Seaweed cultivation largely takes place on long-lines which are suspended below the water (often in grids) and fixed in place by a system of buoys and anchors. Cultivation will generally take place in coastal areas which provide sufficient nutrients and appropriate depth, salinity and temperature. Typically, seeding of long-lines will take place in the autumn with a view to harvesting the following spring or early summer. Harvesting is usually conducted from a boat, with the seaweed either being removed from the long-lines by hand or using some sort of mechanical cutter, and then transferred to land for processing. Seaweed cultivation can also take place alongside fish farming, particularly as a means to reduce the nutrient impacts of this activity.

Benefits and significant risks

Whilst there are many socio-economic benefits to be gained from the sustainable development of the seaweed industry, there are also significant risks if the industry is allowed to expand without taking sufficient account of the potential effects on marine ecosystems or the consequences for other legitimate uses of the marine environment.

SIFT recognises the many socio-economic benefits to be gained from the sustainable development of the seaweed cultivation industry in Scottish waters. We support the progressive expansion of the sector, provided that the potential cumulative effects on marine ecosystems and the consequences for other legitimate uses of the marine environment are taken into account. To that end, we developed and have recently updated a Regulatory Vision for the seaweed cultivation sector.

SIFT has been looking into the potential impacts of seaweed cultivation in Scotland, how those impacts are managed through the regulatory process, and how communities can participate in the process.

Our new resource a guide for community participation in seaweed farm applications details both the impacts and the opportunities for seaweed cultivation in Scotland.

Seaweed farming faces a range of challenges, ranging from competition for space in sea-lochs, to the availability of processing facilities to marketing. There are widely held concerns that these challenges will prevent the establishment of a sustainable, domestically owned seaweed sector, and that instead – like other forms of aquaculture in Scotland – the industry will become dominated by well-capitalised corporations with little direct relationship to coastal communities.

To address these concerns SIFT has published a report on facilitating the development of the seaweed sector in Scotland. The report assesses the role of cooperatives and alternative models for collaboration in meeting key commercial challenges in the sector. A briefing note SIFT Facilitating Seaweed Cultivation Briefing March 2022 sets out our policy position and summarises the key recommendations we believe are necessary to ensure the sustainable expansion of this burgeoning industry.

Most recently, Guidelines for environmentally responsible seaweed cultivation, June 2023 have been developed to help UK seaweed businesses understand the potential environmental impacts of both seaweed aquaculture and wild seaweed harvesting, and to help them incorporate this knowledge into their projects before commencing development. These guidelines have been co-produced by Marine Conservation Society (MCS) and Sustainable Inshore Fisheries Trust (SIFT). They are intended to outline our joint position on environmental best practice for both the development of the seaweed cultivation industry and the wild harvesting of seaweed. The guidelines highlight the most salient environmental issues and signposts other resources that may be informative. It is not a standard, so it does not offer accreditation or certification. MCS and SIFT understand that an industry-led comprehensive code of practice will be developed at a later date by the Scottish Seaweed Industry Association (SSIA), and we hope that these guidelines will inform that code.