The importance of seaweed farming

Seaweed Abundance and Distribution

Seaweeds are macro-benthic (large and attached) forms of marine algae which are among the main primary producers in the shallow areas of seas and oceans. Seaweeds are named after the dominant photosynthetic pigment they possess; thus more than 10,000 different species of seaweed fall into three groups: red (Rhodophyta), green (Chlorophyta), and brown seaweed (Ochrophyta). Although more than 10,000 species of seaweed have been described to date, the main commercially farmed species can be summarized into five major groups (Table 1).

Table 1. Major seaweed production group in 2019

#	Species group	Climate	Industrial application	Production
				Wet tone	%	Cycle
1	Saccharina/Lamiaria	Cold water	Alginate, mannitol, iodine	12,411,987	34.7	8 months
2	Undaria pinatifida	Cold water	Food (Wakame)	2,566,316	7.2	Yearly
3	Porphyra/Pyropia	Cold water	Food (Nori)	2,560,000	7.2	5 months
4	Gracilaria	Warm water	Agar	3,695,231	10.3	30-45 days
5	Eucheumatoids	Warm water	Carrageenan	11,685,174	32.7	45-50 days
6	Others			2,843,796	8.0
	Total			35,762,504	100

Source: (Cai, 2021) and (Poblete-Castro, et al., 2020)

The production of seaweed harvested from the wild collection and from cultivation was equal at about 1.1 million tons in 1969. After half a century, while wild catches remained at 1.1 million tons, aquaculture production cultivated seaweed increased up to 36.31 million tons, accounting for 97% of world seaweed production in 2021. World seaweed farming production increased more than 1,000 times from 34.7 thousand tons to 35.17 million tons from 1950 to 2021. This increase is driven by increasing pressure on food and feed supplies, the need for biological alternatives, and a growing understanding of the unique properties of seaweed, these new innovations have fueled momentum and excitement about the potential of seaweed globally.

Data source: (FAO, 2023)

Figure 1. Status and trends of global seaweed production, 1950-2021

Global Trade and Market of Seaweed

Recently, the global seaweed industry is worth more than USD 12 billion per annum, approximately 32 million tonnes per annum in volume  (Poblete-Castro, et al., 2020). Figure 3 shows that China is the largest seaweed processing country in the world.. The country imported 15% raw seaweed and exported 30% of the world's commercial value of seaweed-based hydrocolloid. Republic of Korea and Indonesia are two largest export of seaweeds countries.  Seaweed export from Republic of Korea is mainly cold water seaweed for human food such as kelp, wakame, nori, where as Indonesia seaweed export is mainly for warm water seaweed – Kappaphycus/ Eucheuma for carrageenan processing. The market for the seaweed is expected to grow steadily up. This increase in market would be felt due to increase in consumption mostly in Europe and United States of America in seaweed-based hydrocolloids. Meanwhile, Asian countries (China, Japan, and Korea) are leading this market segment due to a high number of traditional consumption of seaweed as human foods (Figure 3) (García-Poza, et al., 2022), (Cai, 2021)

Source: (Cai, 2021)

Figure 2. Top 10 export and import of seaweeds and seaweed-based hydrocolloids, 2019

Seaweed products and utilization

Most seaweeds are used as food (sea-vegetables) (70%) and other applications account for 30% including hydrocolloids (carrageenan, alginate, agar), feed, fertilizers, and chemicals (Figure 4) (Poblete-Castro, et al., 2020). Seaweed-derived extracts (carrageenan, agar and alginates) account for almost 40 percent of the world's hydrocolloid market; rest come from certain animals, microbes and land plants (FAO, 2018). The most important commercial crops are Saccharina, Kappaphycus/Eucheuma, Gracilaria and Porphyra (Table 1).  Porphyra (Nori) and Saccharina (kombu) are sold for food purposes at US$16,000 and US$8,000 per dry tonne, respectively (Poblete-Castro, et al., 2020). Whereas the warm water seaweed - Kappaphycus/Eucheuma are sold for carrageenan purposes at only about US$1,000 per dry tonne . However, some of the warm water seaweeds  such as Kappaphycus striatum and Eucheuma denticulatum can also be used as sea-vegetables such as salat, jelly, sweet. Further research and promote the use of warm water seaweeds for human foods need to be invested in.

Source: (Cai, 2021), (Barrington, et al., 2009)

Figure 3. Seaweed products and utilization

Seaweed farming is a family-based business and is considered one of the main sources of livelihood for coastal communities. Moreover, the sector helps to alleviate climate change impacts by absorbing carbon emissions, regenerating marine ecosystems, while promoting a circular economy by supplying more ‘blue food’ from the vast oceans.

References

Barrington, K., Chopin, T. & Robinson, S., 2009. Integrated multi-trophic aquaculture (IMTA) in marine temperate waters. In: D. Soto, ed. Integrated mariculture: a global review. FAO Fisheries and Aquaculture Technical Paper. No. 529. Rome: Food and Agriculture Organization, p. 7–46.

Cai, J., 2021. Global status of seaweed production, trade and utilization. Seaweed Innovation Forum Belize, FAO.

FAO, 2018. The global status of seaweed production, trade and utilization. Rome : Food and Agriculture Organization, Globefish Research Programme.

FAO, 2023. FAO Global Fishery and Aquaculture Production Statistics (FishStatJ). [Online]. Available at: www.fao.org/fishery/statistics/software/fishstatj/en [Accessed 25 05 2023].

García-Poza, S. et al., 2022. Global Trade of Seaweed Foods. In: A. Ranga Rao & G. A. Ravishankar, eds. Sustainable Global Resources of Seaweeds Volume 2: Food, Pharmaceutical and Health Application. Cham, Switzerland: Springer Nature, pp. 325-337.

Poblete-Castro, I., Hoffmann, S.-L., Becker, J. & Wittmann, C., 2020. Cascaded valorization of seaweed using microbial cell factories. Current Opinion in Biotechnology, Volume 65, pp. 102-113.