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Giasuddin Khan

Project Director
Marine Fishery Survey Management
and Development Project, Chittagong

1. Background

In Bangladesh, naturally growing seaweeds are in the littoral and sub-littoral zones of St. Martin's Island. This island is the southernmost land of Bangladesh. Ten species of seaweeds have so far been recorded from the island. These include three species of green seaweeds, two species of brown seaweeds, and five species of red seaweeds. The list of the species is furnished in section 2.2.

The study of seaweed resources is a very recent activity in Bangladesh and complete information and statistics in this regard is not available at this stage. The taxonomic and ecological study of seaweed and other algae has, however, been reasonably completed.

2. Status of Production and Utilization

2.1 General Situation

  1. Approximately 15 metric tons of seaweeds (all varieties) were produced in 1989. The total production was consumed in the country. Bangladesh is not importing seaweeds directly, but in product form e.g., agar. In 1987 the country imported two tons of agar from Japan and South Korea.

  2. Culture methods are yet to be introduced in the country. Nothing was produced by culture. Fifteen tons were produced by gathering from natural stocks. The approximate area of natural seaweeds bed is 10 square kilometers.

  3. In terms of area about 50 square kilometers could be utilized for culture. At present pre-culture studies are going on. The government is preparing a plan for seaweed culture programme because the natural stock would not last long under the present state of harvesting. The question of introducing new species particularly the introduction of Gracilaria, which species is not recorded in the country, may come later.

  4. The government is yet to take up any plan for development of seaweed processing. Natural stocks could not support for long the input needed by processing plants.

2.2 Review of Economic Species

a. List of economic species:

All of the ten species available in the country have economic value. The species are as follows:

  1. Caulerpa sertularioides *
  2. C. racemosa
  3. Entermorpha sp.
  4. Hydroclathrus clathretus *
  5. Sargassum sp.
  6. Gelidiella tenuissima
  7. Helimenia discoidea
  8. Hypnea valentiae *
  9. H. pannosa *
  10. Gelidium pusillum

* Most commonly available species.

At present all the species are being gathered, but the particular importance of any species from the culture or economic point of view is yet to be identified.

2. Production Statistics

Regular statistics on production is yet to be developed. Some information, however, are available from occasional surveys conducted by interviewing the local people. Table 1 was prepared on the basis of those information which have also been treated with some assumptions.

3. Information on Production Systems being followed in the Country

3.1 Scales of production:

There is no seaweed farming system in the country as of now.

3.2 Methods of production and estimated area:

All seaweeds are at present gathered from the wild.

Table 1. Production (MT) and value (Tk) by species.
RED SEAWEEDS            
1.Gelidiella tenuissima0.501500-0.251000-1.002000----
2.Helimenia discoidea2.005000-1.504000----1.001500-
3.Hypnea sp.3.007000-3.006000-2.004000-1.503000-
4.Gelidium sp.0.501500-0.251000-------
BROWN SEAWEEDS            
1.Hydroclathrus clathratus2.002000-1.001500-0.501000-0.50600-
2.Sargassum sp.2.001000-1.00500-1.00200-1.50200-
GREEN SEAWEEDS            
1.Caulerpa sertularioides2.002000----------
2.Caulerpa racemosu1.501000----------
3.Caulerpa sp.---1.501000-1.00600-0.50300-
4.Entromorpha sp.1.501000-1.00500-0.50200----

All the species and quantity produced within the country are either in fresh or in dried (semi-processed) form. Available information/data do not permit separation of the quantities for fresh and semi processed forms.

4. Import of Seaweed Products

All the imported seaweed products was agar (Table 2). Recently Agar Powder has also been directly imported from the USA and UK. The product is available in the local markets, but statistics are not available as to the quantity imported.

Table 2. Importation by product form.
YearQuantity (MT)Country
19871.9Japan, South Korea
19863.0Japan, South Korea, Singapore
19851.3Japan, South Korea
19844.4Japan, South Korea, Singapore

Source: Bureau of statistics

5. Economics of Production

At present seaweeds are only harvested by gathering from natural stock. In comparison to the production this has very little value from the economic point of utilization.

6. Processing and Utilization

Consumed locally both as fresh and as dried for human food as well as animal feed, and only the people in the localities where seaweeds are gathered utilize them.

7. Marketing of Seaweeds and Seaweed products

No formal marketing system has evolved.

8. Problems and Needs

As there is no culture-based production and no processing is done, the problems at this stage are not identifiable.

9. Research and Development Activities and Capabilities

  1. The only government organization engaged in seaweed study is the Directorate of Fisheries which is conducting this work through the Marine Fisheries Survey, Management and Development Project based at Chittagong and Cox's Bazar. The Directorate of Fisheries has almost completed its first phase of study on the taxonomy and ecology of seaweeds including occasional data collection on harvesting. Now DOF is planning a culture-based study on seaweeds. The University of Chittagong and University of Dhaka have also research activities on seaweeds, which are mostly taxonomic work.

  2. No training is received in this regard by DOF personnel either from abroad or inside the country. Related biologists need to be trained in this field to enable them to handle the future programme, but this is not possible within the country as of now.

  3. The government is now planning to expand seaweed production through culture, initially around the natural beds and subsequently to expand and extend them to neighbouring areas possessing similar ecological conditions.


Liang Ling

Department of Aquatic Products
Ministry of Agriculture

1. General Description

Seaweed production in China is mainly from artificial cultivation along the coast, the annual output has reached 250,000 metric tons dried product (1.25 million tons fresh), with a value of about 300 million yuan. The total farming area is about 200,000 mu. The economic species that are being cultured are Laminaria, Porphyra, Gracilaria, Undaria, Gelidium, Eucheuma, etc. among which Laminaria comprises 88% in weight, Porphyra 6% and all others 6%. About 70% of seaweeds is directly used as food or vegetable, 25% as raw material for industry and 5% in food processing. The major processed products are alginate, iodine, mannitol, carrageenan, agar and other seaweed food.

2. The Status of Production

(1) Laminaria (Table 1)

Although its artificial cultivation started in the 1930's, it was not well-developed until the raft culture method was successfully tried and introduced in 1951. It was especially the successful development of the technology of indoor sporeling culture using natural light which caused the rapid development of Laminaria culture. Since the 1970's the government has promoted Laminaria farming technology and the use of appropriate equipment resulting in Laminaria farming expanding from shoal into shallow water. Polyculture of molluscs and seaweed started in the 1980's. This increased the rate of water utilization and income from the farm.

There are 17 large sporeling culture plants in China, with a total sporeling culture area of about 56,000 square meters. Annual production from these plants is 6.4 billion, which is enough to meet the needs of 200,000 mu of culture area.

Laminaria culture is distributed mainly over three provinces. Shandong contributes 60% by weight, Fujian 21%, and Liaoning 17.6%. The main method of cultivation is raft culture. The government has set up not only a set of facilities for sporeling cultivation, harvest, processing, utilization, marketing and management, but also a theoretical system of science and technology for Laminaria cultivation. Thus the culture technology for Laminaria is basically stable and developing.

In 1988, the cost of material for Laminaria culture was about 1018 yuan/mu, labour cost was 923 yuan/mu and the average output was 1400 kg/mu. This translated to a return of 299 yuan/mu at an average wholesale price of about 3.00 yuan/kg.

Table 1. Status of Production of Laminaria.
Output (tons)216,415178,900203,437253,839
Area (10,000 mu)10.89.9611.6317.60
Output per mu (tons)
Export (tons)35950329373

(2) Porphyra (Table 2)

Porphyra culture in China began in 1959 and succeeded in 1966. It then developed in the south coast of China. Porphyra culture was introduced to Jiangsu province in 1968 and developed in 1970.

The chief methods which are used for artificial cultivation of Porphyra in China is raft culture in the tidal zone. The species cultured in Jiangsu province is P. yezoensis, in southern China it is P. haitanensis.

The total culture area at present is 100,000 mu, with an average output of about 160 kg per mu, the total output is about 15,600 tons. The return from one layout is about 400 to 700 yuan per mu.

Table 2. Status of Production of Porphyra.
Output (tons)15,57612,28513,58612,367
Area (10,000 mu)9.599.359.438.95
Output per mu (kg)162131144276

(3) Other Species of Seaweeds (Table 3)

Other species of seaweeds which are cultivated are Undaria, Gracilaria, Gelidium and Eucheuma.

The artificial cultivation of Undaria succeeded in the 1970's using also the raft culture method. Undaria is usually cultured with Laminaria in the shoal.

The production area is concentrated in Liaoning Province, the cultivated area is 5,000 mu and the annual yield is 10,000 tons.

The artificial cultivation of Gracilaria is carried out only in Guangdong, Fujian, Guangxi and Hainan provinces. One method is pond-scattering culture, the other raft culture. At present, the area is about 30,000 mu producing 3000 tons annually.

Eucheuma is cultivated in Hainan island. The method used is transplanting of seedlings and transplant of tied seedlings. Annual output is about 300 tons.

Table 3. Status of Production of Other Species.
Output (tons)12,71212,82513,2863,580
Area (10,000 mu)2.48---------
Output value (10,000RMB)---1,2831,330360

3. Processing and Utilization

Seaweed is utilized in China in four ways: (1) food for direct human consumption such as Laminaria, Porphyra and Undaria; (2) raw material for industrial utilization, the main products being alginate, iodine, mannitol, carrageenan, agar, etc; (3) processed into food or as an ingredient of other food products; and (4) medicine and health food.

There are about 30 Laminaria industrial processing plants. The products -- iodine, alginate and mannitol as well as food products -- are supplied to the pharmaceutical factories, printing and dyeing, weaving, casting and food industries. The annual output of the Laminaria processing industry is 7,500 tons of alginate and 2,000 tons of mannitol valued at about 80 million yuan. About 50% of the alginate is exported, 30% for the local printing and dyeing industry, another 15% for the food industry, and 5% for other uses.

Iodine and mannitol are sold only in the domestic market. In recent years, a lot of work on improving and adapting technology, introducing advanced technology and developing technical cooperation had been done with the view of upgrading product quality and expanding the market for these seaweed products.

The agar processing plants are small-scale operations. There are about 70 plants distributed in Fujian, Shandong, Guangdong and Gungxi provinces, with the bulk coming from Guangdong and Shandong. The raw materials are Gracilaria, Gelidium and Porphyra. The annual output is about 200 tons which are used in the medical, food and chemical industries (Table 4).

Table 4. Output of Agar.
Output (tons)42.421.769.175.9

The production of carrageenan from Eucheuma began in Hainan province only recently. Annual output is about 10 tons and the product is used in the domestic food industry.

4. Marketing

There are two marketing channels for seaweed in China, one is the local Aquatic Products Marketing and Supply Co. which sells seaweeds wholesale for direct human consumption and food processing; the other channel comprises seaweed producers or farmers who sell seaweeds directly to processing plants. The products are sold to the printing and dyeing, food, chemical and medical industries through some other companies.

5. Scientific Research and Development

The seaweed research organizations in China spread along the coast include the Institute of Oceanology, Yellow Sea Fisheries Research Institute and the various institutions of marine fisheries in Liaoning, Shandong, Fujian, Jiangsu, Hainan, Guangxi Provinces, as well as some fisheries university or colleges in Shanghai, Dalian, Zhanjiang, Xiamen, Zhejiang, Qingdao, etc. which also conducts some research and training. At present, the main scientific projects are to cultivate fine varieties of seaweeds and to prevent diseases. We have successfully introduced some new species such as Giant kelp from Southern America and Gracilaria from the Philippines.

The Chinese government constantly pays attention to the development of seaweeds. In 1985, the country's policy on fishery development was readjusted and aquaculture was accorded top priority. Aquaculture was seen as a strategic measure for decreasing fishing pressure on the nearshore area and a readjustment of industrial structure of fisheries. Thus, the seaweed culture industry in China would have a more rapid development in the future.

6. Problems

  1. Production has been restricted by the market, and supply of some products have saturated the domestic market. For instance, the highest annual production of Laminaria has reached 250,000 tons from 12,000 ha of culture area, but it has been readjusted to 200,000 tons annually due to the limited market.

  2. Technology of artificial sporeling needs to be perfected. The technology of sporeling production for some species except Laminaria and Porphyra still needs to be further researched. For Gracilaria, the indoor industrial sporeling production method needs to be developed further in order to supply enough young thallus for industrial culture.

  3. Quality of processed products of seaweeds needs to be further improved. There are still gaps in the quality of locally produced phycocolloids compared with that produced abroad. The quality of agar especially is behind international standard due to the low level of processing technology.

  4. Lack of fund. To develop the culture and processing industry substantial financial support should be given for production and scientific research. Lack of financial resources has slowed down further development of the industry.

7. Conclusion

The total fisheries production in China surpassed 10 million tons in 1988, of which the production from marine water and fresh water culture comprised about 50%. The seaweed culture has played an important role in China's aquaculture industry and has a bright outlook. We believe that with cooperation and hard work among the participating countries of the project RAS/90/002, the seaweed industry should achieve greater progress in the future.


Kisto Mintardjo

Head, National Seafarming Development Centre,
Directorate General of Fisheries
Department of Agriculture

1. Introduction

Seaweeds have been utilized by Indonesians for food (salad, vegetable and soup thickening) and medical treatments. There are many kinds of seaweeds grown in Indonesia, but only three are of high economic value, namely, Gracilaria, Gelidium, and Eucheuma.

Indonesia is a vast archipelago composed of over 13,000 large and small islands with a wide area of marine waters, a very long coastline, and extensive reef areas. The biological and physical characteristics of most of these areas appear to be favourable for seaweed culture.

The culture of Eucheuma and Gracilaria have been developed in Indonesia, but the production of Gelidium is gathered from the natural stock only. There have been no successful culture trials of Gelidium in Indonesia. The culture of seaweed in Indonesia is easily developed, because the potential areas are available, culture techniques and post harvest technology are easy to practice and low investment is needed. There is a large number of fishermen throughout the country who descend from generations of seaweed collecting fisher folks. These fishermen are an invaluable human resource who have the potential to dramatically increase seaweed production.

2. Production

Indonesia's seaweed production increased from 4,098 tons in 1977 to 72,805 tons in 1986. The volume and value of the seaweed outputs are shown in Table 1.

At present the production of seaweed is mostly from the wild because seaweed cultivation still has to be developed in areas like Bali, West Nusa Tengara, East Nusa Tengara, Seribu Island, Lampung, Central Sulawesi, Southeast Sulawesi, etc. (see Table 4).

In 1986 Indonesia exported more than 7,000 MT of dried seaweed valued at US$ 2.154 million (Table 2).

Table 1. Indonesia seaweed production and value (1983–1986).
(Rp 1,000,000.)

Source: Fisheries Statistics of Indonesia (1981 and 1988).

Table 2. Indonesia seaweed export (1979–1986).
(FOB 1,000 US$)

Source: International Trade Statistics of Fisheries Commodities (1986).

In turn, Indonesia imported in 1987 some 239,742 kgs of agar and alginate valued at US$ 3,829.487 (Table 3).

Table 3. Indonesia's agar and alginate import (1981–1987).
(FOB 1,000 US$)

Source: Bureau of Statistics Centre, 1988.

3. Methods of cultivation

There are three species of seaweeds commonly cultured in Indonesia, namely, Eucheuma spinosum, E. cottonii, and Gracilaria sp. A total of 22,600 ha have been identified as potential areas suitable for seaweed culture and 17,700 ha suitable for Eucheuma culture (Tiensongrusmee et al., 1987). The potential areas for culture are shown in Figure 1 and the existing areas for seaweed culture in Indonesia are shown in Table 4.

Table 4. The existing areas of seaweed culture in 1988.
 ProvinceSpeciesProduction area (ha)
1.DKI JakartaEucheuma cottonii0.29
2.West JavaE. cottonii2.77
3.East JavaEucheuma spp.
Gracilaria spp.
4.RiauE. cottonii
E. spinosum
5.LampungE. cottonii100.00
6.BaliE. cottonii200.00
7.West NusatenggaraEucheuma spp.82.60
8.North SulawesiE. cottonii
E. spinosum
9.Central SulawesiE. cottonii1.25
10.South-East SulawesiE. spinosum394.45

Source: Provincial Fisheries Service, 1988.

3.1 Eucheuma culture

Two methods of Eucheuma culture have been developed in Indonesia, the stake and line off-bottom method and the bamboo raft method.

3.1.1. Stake and line off-bottom method

Stake and line off-bottom method culture is mainly practiced in lagoon with flat seabed, where the depth of the water is between 0.5–2.0 m during low tide. This method is operated at 20–30 cm above the seabed.

This culture method is less laborious and economical, easy for maintenance work such as cleaning of the miscellaneous plants, eradication of predators, replanting of missing plants and harvesting. In Serangan Island, Bali and also in West Nusa Tenggara, one culture unit consists of about 500 lines. Each line accommodates 25 plants at a distance of 20–25 cm apart. The culture system is supported by stakes which are pegged at one meter apart. The stake is 2.5 cm in diameter and 75–100 cm in long.

Figure 1

Figure 1. Potential areas for Eucheuma culture in Indonesia.

3.1.2. Raft method

Usually a floating raft used for seaweed culture is made of bamboo, and uses polyethylene as a culture supporting system. The size of raft ranges from 2.5×5.0 m to 5.0×10.0 m depending on management. This method is suitable for the sites that have sloping seabed which is not feasible for the stake and line off-bottom method. The method also offers a constant-level planting. The level is chosen for optimum light intensity to obtain the highest yield.

The bamboo raft is 2.5×5.0 m, and polyethylene lines 2.5 m in length are tied parallel to one side of the raft. One raft accommodates 25 lines which are arranged at 20 cm distance. Each line has 20 plants and one raft 500 plants.

3.2 Gracilaria culture

Gracilaria are cultured in ponds. Depth of ponds vary from 60 to 80 cm. The pond bottom is generally sandy loam (pond bottom with very soft mud should be avoided). The planting material should be cut into pieces and broadcast uniformly on the pond bottom.

4. Processing and utilization

Seaweed is utilized in Indonesia mostly as food and raw material for industrial use. Many species of seaweeds are eaten as vegetable salad and prepared in various ways (Table 5).

There are many small agar extraction plants in Indonesia, but none for the carrageenan-bearing seaweed (Eucheuma) which is the main species of seaweed produced in Indonesia. Most of the carrageenophytes are exported in dried form.

5. Marketing

One of the major constraints to seaweed production in Indonesia especially for Eucheuma is marketing. The demand for Eucheuma is dependent on carrageenan manufacturers in other countries such as the United States, France, Denmark, Japan and the Republic of Korea.

Like other agricultural commodities, the price of seaweed fluctuates depending on the source, quality and purity of the dried product, availability of raw materials and the development of its applications to industry.

Table 5. Modes of seaweed utilization in Indonesia.
Mode of Utilization Species Main areas of 
1.Consumed raw, cooked-Caulerpa pellata-Bangka
  -Chaetomorpha japonica-Ambon
  -Sargassum granuliferum-South Sulawesi
  -Turbinaria ornata-Ambon
  -Acanthophora spicifera-Kangean island
  -Corallopsis salicornia-Bali
  -Gracilaria lichenoides-Ambon
  -Hypnea cenomyce-Several areas
  -Hypnea cervicornes-Maluku
2.Consumed as jellies-Eucheuma edule-Java
  -E. spinosum-Thousand island
  -E. serra-Java, Bali
  -Hypnea divoricata-Timor
3.Used as medicine-Acetabularia major-Java
  -Hypnea musciformis-Several areas
4.For agar production-Gelidium rigidum-Java
  -G. latifolium-Java
  -Gracilaria conferfoides-Java
  -G. lichenoides-Java

Source: Zaneveld, J.S. (1955).

Indonesia's seaweed production increased from 4,098 tons in 1977 to 72,865 tons in 1986 (Table 1). Of this total only 7,111 tons were exported in 1986 (Table 2). The rest was used for human consumption and agar manufacture in the local market.

5.1 Domestic market

The market is characterized by a large number of small-scale producers who sell to small-scale collectors/middleman. The middlemen sells the product as one of the items he trades (miscellaneous marine products) and thus could not be described as a specialist.

Indonesia has a good domestic market for seaweed. It is estimated that in the Lombok island, West Nusatenggara alone the local market for the traditional use of Eucheuma spinosum (“pencok”) is about 1,500 kgs (wet weight) per day or about 400 tons (wet weight) per year. It is expected that this figure will rise if production of seaweed increased. “Pencok” is a product for human consumption, a boiled preparation wrapped in banana leaf. It is estimated that 80% of all seaweed production in Lombok island is for human consumption, which can give a higher cost of return to the farmer. In addition, Indonesia imported 239,742 kgs agar and alginate in 1987 valued at US$ 3.83 m (Table 3). This suggests that the prospect of the domestic market for seaweed is bright.

5.2 International market

In 1986 Indonesia exported about 7,111 tons of dried seaweed to the world market valued at about US$ 2,154,000. In 1986 export of seaweed from Indonesia was a direct trade to the manufacturers of importing countries. Most of the product passes through brokers in Singapore or Hong Kong and re-exported to other target markets (Table 6), while the exporters are based in Surabaya, Bali and Ujung Pandang.

Table 6. Export volume and value of seaweed by country destinations in 1986.
 CountryVolume (Tons)Value (FOB US$)
2.Hong Kong4,207.2031,151,488
3.South Korea91.06234,444
6.United States30.00010,000

Source: International Trade Statistics of Fisheries Commodities (1986).

6. Problems and needs

6.1 Marketing

Since seaweed farming is still being developed in Indonesia, marketing of the product is also a major problem to the farmers; there are no commercial or industrial scale carrageenan manufacturing facilities in Indonesia, so that the price of Eucheuma is not stable.

The price of dried product is many times lower than the semi-refined or refined product. In addition, its demand and price is also dependent on the importing country. It is advantageous to establish a manufacturing plant to accommodate the growth of the industry even with a semi-refined manufacture. Although the price of semi-refined product is 50% lower than that of refined ones, the process is faster, easier, cheaper and needs lower level and less expensive technology.

6.2 Environmental factors

Environmental factors such as salinity, light, temperature, water movement and transparency affect the growth rate of the Eucheuma and other seaweed species. During the rainy season (October-April) the growth of the seaweeds slows down and sometimes all the plants can be damaged. The specific cause of this syndrome, known as “ice-ice”, is not known. But it has been associated with environmental deterioration.

7. Research and development activities

Seaweed research is needed to provide the basis for culture development. Research would provide answers as to whether species and/or culture technologies used elsewhere can be applied in the local environment. Cultivation techniques and ways to monitor the impact of development on the environment must be given priority.

There are three research institutions that cover seaweeds in Indonesia. Their activities include seaweed development such as culture techniques, environmental and biological research, post harvest technology, etc. These are the:

  1. Marine Fisheries Research Institute, under the Agency for Agricultural Research and Development

  2. Agency for Research and Development of Oceanology, under the Institute of Science

  3. Agency for Assessment and Application of Technology, under the State Minister of Research and Technology

Seaweed culture requires low capital investment but gives a fast turn over. Its development can help improve the economic conditions of residents in Indonesian fishing communities who are poor and have limited resources. The seaweed culture is economically viable both in small-scale and large scale operation. The culture techniques are also well established and easily adopted by fishermen.

The current seaweed development activities are mainly on the following concerns:

  1. Small holder seaweed farming

  2. Commercial operation


Masao Ohno

Usa Marine Biological Institute
Kochi University
Usa-cho, Tosa, Kochi, 781-11

The development of cultivation methods of main edible seaweeds have almost succeeded in Japan. The cultivation techniques of seaweeds used for salad, such as Tosakanori (Meristotheca) and Umibudo (Caulerpa) are being tested. The seaweed scientists in Japan are now using biotechnological methods to select seaweed strains of good quality (high growth rate, good taste, etc.). This paper describes in brief the culture methods of the main seaweed species in Japan.

1. Cultivation Techniques of Nori (Porphyra)

The process flow diagram of nori cultivation is shown in Figure 1. The entire life cycle of nori is controlled artificially. The special features of nori cultivation include the following: 1) Horizontal suspending nets are used as standard method of cultivation; 2) The application of refrigeration technique for bud net allows the culture of 2–3 crops per season; 3) Cultivation of nori by the floating method used in culture grounds of more than 5 meters deep. 4) Mechanization is employed mostly for harvesting and processing. 5) Activities are being carried out to select and propagate species and varieties with rapid growth and excellent quality (Miura, 1975, Saito, 1979).

At present, there is an oversupply of nori. High quality nori has a high market price especially following the improvements in dietary habits of people, but low quality nori has a low price and its oversupply has led to a low overall market price. In order to stabilize nori cultivation economics, it is necessary to produce high quality product, reduce the production cost, and increase the harvest per culture unit. To increase harvest per culture unit and produce high quality product, cultivators will have to make efforts at a reasonable utilization of culture grounds (e.g. reducing the number of culturing facilities, and rearrangement of the division of culture ground depending on productivity), cooperation for each type of cultivation, and breeding of species with superior quality and more resistance to disease. As it is difficult in Japan to increase the demand for nori, producers will have to make efforts at a more efficient production even as dealers are making efforts to stimulate more consumption of nori (Saito, 1984).

Figure 1

Figure 1. Flow diagram of Porphyra cultivation.

2. Representative Methods of Kombu (Laminaria) cultivation

The cultivation method of Laminaria is introduced here by Kawashima's report. The three representative methods of Kombu cultivation which are actively used in Hokkaido are shown in Figure 2.

(1) Two-year Cultivation

All the cultivated Kombu in Hokkaido are biennial plants. The two-year cultivation is a very orthodox method to reproduce faithfully the life cycle of the natural biennial Kombu. It was the first cultivation method attempted in Hokkaido and is even now widely used as a basic cultivation method in the eastern and northern districts as well as in a part of southwestern district of Hokkaido.

In this method, seedling production starts in October. After that, plants are left to grow through two winter seasons and harvested in July and August after three calendar years. Consequently, this method produces a two-year Kombu crop which is almost of the same quality as the naturally growing plant. However, the biggest problem with this method is that it takes more than 20 months from seeding to harvest and it results in a comparatively high price of the product.

(2) Cultivation by transplanting

Kombu is able to attach not only to rocks but also to ropes, wooden posts, piles and other substrata in the sea. This ability is most promoted from winter to spring when the activity of the meristem increases and new holdfasts are formed. During this time the fishermen can successfully thin out the excess fronds completely with holdfast from the cultivation ropes and transplant the thinnings by fastening them to a new rope with thin, soft tape.

In about ten to fifteen days new haptera grow and fix the frond firmly to the new cultivation rope. Natural Kombu washed up on land by storms is sometimes used. The advantage of this method is that it conserves manpower and materials. It is often combined with the other cultivation methods in order to increase production, as shown in Figure 2.

(3) Forced cultivation

Because the two-year cultivation method takes over twenty months to complete, there can be only one harvest every two years in one fishing ground. To solve this problem, Hasegawa (1971) and his co-workers developed from 1966 to 1970 a method that would cut the production time to half, and yet produce plants of the same quality as the two-year Kombu at Mimamikayabe, the most famous Ma-Kombu producing district in Oshima Province, Hokkaido. The epochmaking new cultivation technique that resulted from this method has since spread widely to south-western Hokkaido. At present, the production from this method accounts for 92% of the total cultivated Kombu produced in this district.

Figure 2

Figure 2. Diagrammatic flow chart of three representative Kombu cultivation methods in Hokkaido.

There are four basic technological features of the forced cultivation method.

  1. Seedling production is done as early as possible., Usually, in southwestern Hokkaido, seeding is carried out from the end of August to the middle of September. This seeding period is about 30–45 days earlier than that of the two-year cultivation. The subsequent culture of zoospore germling in tanks is continued for about 45 days.

  2. Regular cultivation in the sea begins immediately after the water temperature of the fishing ground has reached 18°C or less. This is around the middle of October in southwestern Hokkaido.

  3. The Kombu must be grown as quickly as possible when the water temperature is lowest. This is during winter until the end of February when the water temperature is 3–5°C. Because the Kombu grows quickly and densely on the cultivation ropes, the fishermen must drastically thin them out during midwinter, from the end of December to the beginning of March. Finally 4–5 plants should remain where each piece of seedling string was originally inserted in the cultivation rope. This corresponds to 12–15 plants per meter of cultivation rope. At the same time, since the sea is very rough during winter, it is important to secure weak haptera to the ropes with thin, soft synthetic tape to prevent the plants from being washed away. At present, the forced cultivation method does not adapt well to the fishing grounds in northern and eastern Hokkaido because such exacting work as thinning and fastening the plants is very difficult to do under the much harsher winter conditions in those areas.

  4. Insure that the Kombu receives proper exposure to light. Beginning from March the weight and length of the blade increase with photosynthetic activity. To increase light exposure, the vertically hanging cultivation rope is raised gradually to within two metres of the water surface. At this point the rope is secured horizontally with its lower end attached to the neighbouring main line. This should be completed by the end of May and, as a result, all the plants should be exposed to uniform light conditions. In the last stage of regular cultivation, the horizontally secured ropes are raised further to within half a meter of the water surface.

Up to the present, the theoretical basis of forced cultivation has yet to be solved satisfactorily from the physiological point of view, although a great deal of interest has been taken on the ecological phenomena by practical cultivation experiments. The force-cultivated biennial plant grows very rapidly for four months around March when the water temperature is at its lowest. On those plants which grow especially rapidly, distinct zoosporangia begin to form near the upper end of the blade. As the blade continues to grow, its apical portion withers and is washed away. In late summer when the plant has attained a sufficient size and weight, the blade produces zoosporangia for the second time on the basal portion.

This process of producing zoosporangia at two different periods is in common with typical biennial Kombu which produces zoosporangia once on the first year blade and then again on the second year one. It can be seen that the force-cultivated Kombu compressed the life span of the natural biennial Kombu into one year and is different from natural Kombu which produces zoosporangia only once in a lifetime.

3. Method of Undaria cultivation

The method of Undaria cultivation was described by Akiyama and Kuroki (1982) as follows: The history of the cultivation of Undaria in Japan is not old. Experimental study of its cultivation by artificial seedling began around 1950. And from about 1960, fishermen tried culturing it. For cultivation in the sea, three methods have been devised as seen in Figure 3. One (A) is vertical hanging of culture ropes from a single floating line. The distance between hanging culture ropes is about 0.5–1 m, the second (B) is horizontal hanging of culture rope from bamboo rafts provided with three lines, and the third (C) is horizontal hanging from a single floating line. The distance between hanging ropes is about 2.7 cm and 18–20 cm between tufts of plants.

The length of the raft is 36–54 m while the line is 100–200 m. The last method (C) can best withstand strong waves and is most appropriate for cultivation in the open sea.

The first step is seeding in a vessel on land. This involves attaching zoospores to the seed strings using the sporophylls gathered from the sea. The second step is rearing the seedling attached to the strings in a vessel such as a concrete tank on land, or rearing them directly in the sea. The third step is planting out seedlings, on the seed strings, to the sea to stimulate them to grow strongly. The fourth step is attaching the seedlings to the strings. The fifth is hanging the culture rope from the culture line or raft in the sea. Then the seedling is left to grow until the Undaria plant is harvested.


Akiyama, K. and M. Kurogi. 1982. Cultivation of Undaria pinnatifida (Harvey) Suringar, the decrease in crops from natural plants following crop increase from cultivation. Bull. Tohoku Reg. Res. Lab. 44, 91–100.

Hasegawa, Y. 1971. Forced cultivation of Laminaria. Bull. Hokkaido Reg. Fish. Res. Lab. 37, 49–52.

Kawashima, S. 1984. Kombu cultivation in Japan for human foodstuff. Jap. J. Phycol. 32, 379–394.

Saito, Y. 1984. Seaweed aquaculture in Japan - its present status and future prospects. TML Conference Proceeding 1, 111–128.

Figure 3

Actual cultivation is carried out in sequential steps as follows.

  1. Seeding in land — summer
  2. Rearing seedlings in land (or sea) — summer to autumn
  3. Outplanting seedlings (seed strings) to sea — autumn
  4. Planting seedlings (seed strings) to culture rope — autumn
  5. Hanging culture rope in sea — autumn
  6. Harvesting — spring

Figure 3. Facilities for Undaria pinnatifida cultivation.



Usa Marine Biological Institute
Koichi University
Usa-cho, Tosa, Kochi 781–11

1. Introduction

The total seaweed production in Japan from natural bed and from cultivation was recently estimated to be about 650 thousand tons annually. The production of cultivated seaweeds was about 615 thousand tons. Culture of the edible seaweed, Porphyra, in Japan was established long ago. The culture technology for the other edible seaweeds, Undaria and Laminaria, was developed some 20 years ago. The production of materials for seaweed salad is increasing recently. The brown algae, Nemacystus decipiens, Cladosiphon akamuranus and the red algae, Meristotheca papulosa are expensive. The total income from the production of seaweeds in Japan is about 180,000 million yen (US$ 1,200 million) annually. Seaweeds for the extraction of agar, carrageenan and alginic acid were imported; about 56 thousand tons worth 16,959 million yen (US$ 113 million) from 23 countries in 1984.

This paper describes in brief the present trend of production of seaweeds in Japan and their prospects.

2. Cultivated Seaweeds

At present, the species of seaweeds cultivated in Japan include green algae, Hitoegusa (Monostroma), Aonori (Enteromorpha), brown algae Mozuku (Nemacystus), Okinawamozuku (Cladosiphon), Wakame (Undaria), Kombu (Laminaria) and red algae Nori (Porphyra). These are edible seaweeds. Brown algae Hiziki (Hizikia) is the traditional edible seaweed, but was not cultivated in Japan. Cultivated materials of this species are obtained from Korea. Recently, many other species, such as Iwazuta (Caulerpa), Habanori (Endarachne), Tosakanori (Meristotheca), Mukadenori (Grateloupia), Ogonori (Gracilaria), etc. have been used due to the great variety of foodstuffs now in demand. These species are being tested for cultivation.

Monostroma, Enteromorpha and Ulva

Monostroma is cultivated in brackish waters in the middle and southern coasts of Japan. The fronds are chopped fine and prepared in paper-thin sheets eaten in Japan in a variety of ways. The main culture grounds are located in warm waters. The production of Monostroma is about 1,000–1,500 tons dry weight annually (Table 1).

Enteromorpha grows abundantly in large river mouths or along marshy coasts. Fronds growing at natural bed are harvested and air dried to be grilled or powdered for use in a number of dishes. The production is about 1,000–1,300 tons dry weight annually (Table 1), but the demand cannot be met by the natural production. Recently, the cultivation of Enteromorpha was started at several river mouths.

Table 1. Annual production of green seaweeds in Japan.
 Piecesx 1000
Cultivated Monostroma spp. Dry matter
 Total production
(D.W. ton)

Ulva grows on the many coasts where nutrient is plentiful. Recently, new species of Ulva from foreign countries might have spread to many places of Japan. These can be eaten as the submaterials of Enteromorpha. Harvested fronds was estimated at about 1,000 tons dry weight annually.


Caulerpa lentillifera growing in the tropical coast of Okinawa have been harvested since a long time ago. The fronds have recently been cultivated in the coral reefs of Isigaki Island and a lot of production is expected to satisfy demand for seaweed salad. The products have already been used in Japanese restaurants in Osaka and Tokyo and in other places.


Three species of Undaria -- U. pinnatifida, U. undarioides and U. peterseniana -- are eaten in Japan. The fronds are gathered from seabed by boat-borne fishermen using scythes attached to long poles. Today, although wild fronds are still gathered, the alga is extensively cultivated in Japan (Table 2). They are used in many kinds of dishes as seaweed vegetable. The total production of natural and cultivated Undaria is about 120 thousand tons annually. About 30 thousand tons more are imported from Korea annually.


The production of Laminaria from natural bed ranges from 120 to 180 thousand tons annually (Table 2), but the demand for Laminaria has been lower. Modern Laminaria cultivation using high quality species was started in 1970 along several coasts of Hokkaido by fishermen (Hasegawa, 1972). The annual production of cultivated Laminaria in Japan jumped from 284 tons wet weight in 1970 to 44,220 tons in 1988. Production from culture was about 30% of this total. The supply of Laminaria is now sufficient in Japan and no great demand for edible material is expected in near future. However, due to the strong demand for good quality product and materials for industrial use, forced Laminaria cultivation method in large scale may be considered for further development.

Brown algae, Cladosiphon (Okinawamozuku) and Nemacystus (Mozuku)

Due to the increase in consumption of different varieties of foodstuffs, there was a rising demand for Cladosiphon and Nemacystus recently. The success in Cladosiphon cultivation was achieved in the warm waters of the southern part of Japan from about 1975.

As there are no accurate statistical data concerning Okinawamozuku cultivation, the exact production and production value are not known, however, the production from cultivation in the lagoon in the South West Islands is about 4,000 5,000 tons, higher than that from natural bed (Table 3). At present, there is an oversupply of Okinawamozuku due to a defect in the marketing system for the product which results in depression in prices (Saito, 1984).


At present about 30,000 families are engaged in Porphyra cultivation on grounds of about 62,000 ha. They produce about 10 thousand million sheets (one sheet of Porphyra is about 20×20 cm in size and about 3.75 g dry weight), valued at 160 thousand million yen (Table 4.)

There is an oversupply of Porphyra products. High quality Porphyra has a high market price. As it is difficult in Japan to increase the demand for Porphyra, producers will have to make efforts to produce high quality material depending on the consumption trend. Moreover, producers and dealers are making efforts to stimulate consumption of Porphyra in the U.S.A. and other countries.

Table 2. Annual production of brown seaweeds in Japan. (Wet Weight).

Table 3. Annual production of Cladosiphon okamuranus.
 Okinawa prefectureKagoshima prefecture

Table 4. Annual production of red seaweeds.
wet weight
Gloiopeltis spp. 
Other red seaweed

* Almost production of them is Cladosiphon okamuranus produced in Okinawa.


The production of Gelidium for agar was highest, at 21,321 tons, in 1967. Recently it has gone down to 8,000–10,000 tons annually (Table 4). Gelidium is are used for the production of the traditional agar in Japan. Most of the industrial agar has been produced from imported Gracilaria materials. The demand for high quality Gelidium is increasing because of the rising demand for agar products of high quality in Japan.

Other useful seaweeds

Red algae like Ogonori (Gracilaria verrucosa), Tosakanori (Meristotheca papulosa), Hunori (Gloiopeltis furcata), Tsunomata (Chondrus ocellatus), Kirinsai (Eucheuma catrilagineum), Komenori (Carpopeltis flabellata) are used in Japan either fresh or salted. These seaweeds are more often marketed as somewhat more expensive food items. There is no data on their production, but the total production is estimated at 500 tons wet weight annually (Table 4).

3. Imported seaweeds

In Japan, seaweed production is 1,200–1,500 thousand tons annually (Table 5 and 6). In addition, a large quantity has been imported, for food or as industrial materials, from various countries as shown in Table 7 and 8. The total amount was 56,140 tons and valued at 16,968 million yen (about US$ 113 million) in 1984. Edible seaweeds such as Undaria and Hizikia are imported from China and Korea. The seaweeds for the materials of agar and alginic acid are also imported from Asia and South America (Table 9).

Table 5. Seaweeds imported in 1990.
ItemUndariaOther edible seaweedsSeaweeds for alginGelidiumGracilariaOther seaweeds
1 US$ = 150 yen

Table 6. Agar product in Japan.
 Exported agarImported agarProduction

Table 7. Imported seaweeds from each country (Kg).
Edible seaweed907,844--1,192,20529,670----53,520----
Gracilaria (Eucheuma)48,61747,010--77,14815,2103,0001,470,31069,22745,540

Table 8. Imported seaweeds from each country (Kg).

Table 9. The production of Gracilaria in the world and imported goods of agar materials from other countries.
CountryCollect quantity per year
Japan import quantity 
1989 Jan-Sept
1988 Jan-Dec
Japan1,200 – 2,200   
North Korea200 – 3002186 
South Korea60 – 80-- 
Taiwan60 –1003417 
China1,200 – 1,50047369 
Vietnam150 – 2003091 
India100 – 1503116 
Sri Lanka100 – 150219 
Philippines300 – 400688906Import quantity contain
Indonesia300 – 400726368Eucheuma
Portugal150 – 2006040 
Italy800 – 1,000234162 
Turkey200 – 400175319Including Cyprus
South Africa1,200 – 1,200839661 
Chile10,000 – 13,0001,3401,800 
Argentina2,000 – 2,50030280 
Brazil800 – 1,000167389 
Total18,620 – 24,7804,8395,213 

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