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Sustainability is at the heart of all we do at Uist Asco. A three-pronged approach balances the ecological, societal and economic sustainability required to ensure Uist Asco will have a presence in the Outer Hebrides’ landscape for many generations to come. 

Our target species, Ascophyllum nodosum (egg wrack or knotted wrack), is the predominant intertidal 

Scottish Knotted Wrack

seaweed found on sheltered rocky shorelines in the North Atlantic. It thrives in the cooler waters around Uist, especially the protected sea lochs found along the entire eastern length of our island archipelago. As an intertidal species, it is covered, then uncovered, by seawater twice a day with the rise and fall of the tides. This ability to cope with such extreme changes in environment is partly what makes it such a valuable seaweed and results in it being so nutrient dense.  

Ecological Sustainability

North Uist CoastlineAscophyllum nodosum is an essential ecological resource, providing a habitat and feeding grounds for several creatures including invertebrates, shorebirds and marine mammals. For this reason, the resource must remain in a healthy state. 

The Resource Science Team here at Uist Asco is responsible for monitoring and assessing the health of Ascophyllum beds and providing biomass estimates that guide our sustainable management strategies. This requires constant field assessment, and our team can often be seen on the shoreline during low tides. This ongoing research is based on a strong scientific foundation and utilises cutting-edge techniques and technologies. 

Our harvest management plan adopts a tightly controlled conservative approach in areas deemed suitable for commercial harvest. These areas are first divided into sectors which can then be micro-managed on an individual basis. Using this methodology, the annual biomass harvests represent less than the total annual regrowth and minimises the short-term human impact in a single area by spreading Harvesters throughout the sectors. 

As part of our dedication to quality in every department, we have introduced a new harvesting method in Uist to complement the traditional methods still employed by many of our Harvesters. The boat and rake method of harvesting has been adopted from a tried-and-tested sustainable model. It is a hand-harvesting technique that consistently delivers clean, fresh seaweed. Using a specially designed cutting rake, only the upper portion of Ascophyllum is harvested, which leaves a large percentage of the biomass intact and allows fast regeneration of the resource.

Societal Sustainability

Scotland has a long history of harvesting seaweed, and the Uists have always been a stronghold for this traditional custom. Historically, crofters used knotted wrack as a fertiliser on their crops, and more recently certain species were used in the production of glass or for the extraction of alginates. 

Uist Asco Seaweed Harvest

Today, Uist Asco continues this tradition, with sustainably harvested seaweed now a responsibly sourced natural ingredient used in the production of animal feeds and soil conditioners.

Uist Asco has provided specialised harvesting boats and training to the local community. Our new harvesting method reduces the physicality of the harvest, improves Harvester efficiency and income and opens up the practice to a broader range of Harvesters. 

Economic Sustainability

Uist Asco is dedicated to the well-being of Uist, whether it is the health of the local seaweed resource or the local economy – we feel the two go hand-in-hand. Our company will continue to preserve the Scottish seaweed resource through proven scientific methods as we continue to grow the Uist economy.   To do this, we support local harvesters, the development of harvesting infrastructure and work with local businesses and the community for the benefit of all.  


The author, Malcolm Gibson, is Uist Asco’s Resource Biologist. 


Scottish Seaweed, Harvested Sustainably, for a Better Future.