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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 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.