Seaweed farming

Seaweed farming or kelp farming is the practice of cultivating and harvesting seaweed. In its simplest form farmers gather from natural beds, while at the other extreme farmers fully control the crop's life cycle.

The seven most cultivated taxa are Eucheuma spp., Kappaphycus alvarezii, Gracilaria spp., Saccharina japonica, Undaria pinnatifida, Pyropia spp., and Sargassum fusiforme. Eucheuma and K. alvarezii are attractive for carrageenan (a gelling agent); Gracilaria is farmed for agar; the rest are eaten after limited processing.^[1] Seaweeds are different from mangroves and seagrasses, as they are photosynthetic algal organisms^[2] and are non-flowering.^[1]

The largest seaweed-producing countries as of 2022 are China (58.62%) and Indonesia (28.6%); followed by South Korea (5.09%) and the Philippines (4.19%). Other notable producers include North Korea (1.6%), Japan (1.15%), Malaysia (0.53%), Zanzibar (Tanzania, 0.5%), and Chile (0.3%).^[3][4] Seaweed farming has frequently been developed to improve economic conditions and to reduce fishing pressure.^[5]

The Food and Agriculture Organization (FAO), reported that world production in 2019 was over 35 million tonnes. North America produced some 23,000 tonnes of wet seaweed. Alaska, Maine, France, and Norway each more than doubled their seaweed production since 2018. As of 2019, seaweed represented 30% of marine aquaculture.^[6]

Seaweed farming is a carbon negative crop, with a high potential for climate change mitigation.^[7][8] The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate recommends "further research attention" as a mitigation tactic.^[9] World Wildlife Fund, Oceans 2050, and The Nature Conservancy publicly support expanded seaweed cultivation.^[6]