Globally aquatic algae account for a significant percentage of aquaculture production, with Asian countries dominating production. The world production of marine macroalgae, or seaweed, has more than tripled, up from 10.6 million tonnes in 2000 to 32.4 million tonnes in 2018. Global demand continues to increase and the number of uses for the product also increases.

The tropical seaweed species (Kappaphycus alvarezii and Eucheuma spp.) as raw material for carrageenan extraction has been the major driver in the increase of farmed seaweed production in the past decade. Seaweed has been produced for a variety of uses, such as for direct human consumption or processed into food additives and nutraceuticals, feeds, fertilizers, biofuels, cosmetics and medicines, amongst other. Seaweed has many health and nutritional benefits, however composition and nutritional value varies by species, season and geography, and the bioavailability of many ‘beneficial seaweed compounds’ to humans or animals needs to be further studied.

According to FAO statistics (2021) of the top six most cultivated seaweed, composing over 90% of production, were:

1. Laminaria japonica or Saccharina japonica
2. Eucheuma spp
3. Gracilaria spp.
4. Undaria pinnatifida
5. Porphyra spp. or Pyropia
6. Kappaphycus alvarezii

The main producing countries were China, Indonesia, republic of Korea and the Philippines, which were also those that cultivated the greatest diversity of seaweed species. 

Here is a short journey through SAMS experimental seaweed farm near Oban on the west coast of Scotland, including the seaweed nursery, and laboratories where they are carrying out research into aspects of seaweed cultivation. 

https://www.youtube.com/watch?v=twGeE3PtVXo

Here you have the North Sea Farms talking about their experiences and the challenges for off-shore seaweed cultivation. Their site is located 12km off the shore in the Netherlands.