In the UK, harvesting of wild seaweeds for food, feed and fertilizers has been carried out for centuries, however seaweed farming does not have a long history. Nevertheless, in recent years, there has been increasing interest in seaweed aquaculture, mainly driven by research into algal biofuel technologies.
Seaweeds could become an important source for third generation biofuels production as its aquaculture does not compete for land and freshwater with either food or non-food crops.
Furthermore, seaweeds have high productivity, fast growth rates and high polysaccharide content; all important qualities for biomass for biofuels.
Macroalgae could also represent a significant sink for anthropogenic CO2 (“Blue Carbon”), and cultivation and the harvesting of seaweeds could play an important role in carbon sequestration and reduction of greenhouse gas emissions.
Due to our extensive coastline, seaweed production in the UK could be increased beyond the current level through farming. However, various limitations to the development of the seaweed sector are perceived by industry and there is a need to establish how macroalgae cultivation can be carried out at a large scale in an environmentally and economically sustainable manner.
The aim of this report is to give Defra an overview of the national and international seaweed sector and its products, as well as an overview of constraints to further development of the sector, particularly in the UK.
The report also aims to identify potential gaps in the regulatory and licensing system for seaweed aquaculture, and to identify the services that Cefas could provide to ensure the development of this area occurs respecting the relevant regulations and the health of the marine environment.
Estimates from the FAO indicate that China alone accounts for 50.8% of the world production of aquatic plants (in 2014). In the period 2009-2013, Indonesia, Peru, and France saw the biggest growth in production of seaweeds from wild harvest, while Solomon Island and Indonesia made the biggest advance in seaweed production from aquaculture. The FAO database has no records of production for the UK although seaweed production from wild harvest in the UK, in 2013, has been estimated at around 2,000-3,000 dry tonnes (AB-SIG 2013).
In addition, unknown quantities of subtidal kelp and storm-cast seaweeds are also collected in the UK. To our knowledge, there are no comprehensive estimates of seaweed production in the UK.
Furthermore, there are no recent estimates of the wild seaweed standing stock of the UK, nor of the potential algal stock that could be sustainably harvested (with exception of Ascophyllum nodosum stocks in the Outer Hebrides which were investigated in 2010). Seaweed aquaculture is currently limited in the UK and existing pilot seaweed farms remain in research and development status.
Multiple products can be obtained from seaweeds, ranging from food to chemicals and bioenergy. For the UK, a total of 27 seaweed-related businesses were identified, based on web searches; 16 of them use seaweeds harvested in the UK. The majority of UK seaweedrelated businesses produce seaweeds for food (or “sea vegetables”) or condiments, and for cosmetics. Other products, based on seaweeds and produced in the UK, include animal feed and supplements, chemicals (e.g. hydrocolloids), fertilizers and nutraceuticals (e.g. nutrients and dietary supplements). Production of seaweeds for other uses such as bioremediation, or biofuel production (via anaerobic digestion), is at the development stage.
There are various issues and barriers limiting or affecting the development of seaweed production and markets. In Europe and the UK, there is a perceived bottleneck in the seaweed supply chain in terms of production capacity (result of high costs for seaweed biomass production and/or shortage of seaweed biomass due to seasonality).
Seaweeds aquaculture could contribute to meet the demand for algal biomass; however, factors such as lack of information on operational costs, potential biomass yields and ecological effects of seaweeds farms, as well as unclear regulatory context (particularly for marine licensing), are perceived to limit the development of the seaweed aquaculture industry.
It appears, however, that there is no specific regulation for seaweed farming in the UK and the established licensing procedure for finfish and shellfish would not always be applicable to seaweed farms. The lack of information on potential environmental impacts of seaweed farms and their management (e.g. control of nuisance species) results in uncertainties for the regulator on how to interpret requirements under national and international regulations (for example, under which circumstances an Environmental Impact Assessment would be required).
Cefas expertise can contribute to clarify the potential for sustainable harvest, and the potential environmental effects of large-scale seaweed farms. In addition, we can help develop the marine licensing procedure for offshore cultivation and, more generally, Cefas can contribute towards creating roadmaps to identify and prioritise activities and policies to accelerate blue growth.
To enable further development of the seaweed industry in the UK, further work and investments should be directed at:
- determination of the seaweed standing stock in the UK and of the amount of seaweed that could be sustainably harvested;
- development/update of regulations/licensing procedure, to account for seaweed aquaculture;
- development/maintenance of pilot farms for investigating seaweed species/strains and growth rates; yield; costs (setting up and running a farm); potential environmental effects; farm locations; storage of surplus algal biomass;
- Life Cycle Analysis of products (e.g. is economically viable to produce seaweed as biomass for biofuels production?), and development of supply chains for seaweedrelated products;
- knowledge transfer between research and industry, with development of algalbusiness clusters.
It would also be important to obtain and record comprehensive figures of annual seaweed
production for the UK (which could then be submitted regularly to the FAO).
