P.M.A. Jayasuriya
Research Officer
National Aquatic Resources Agency
Crow Island, Mattakkuliya
Colombo 15, Sri Lanka
1. Introduction
Sri Lanka has a coastline of approximately 1700 km along which many varieties of seaweeds are found. About 320 species belonging to different families have been identified by several workers (Durairatnam, 1961; Barton, 1903; and Boergesen, 1936).
In 1952 the Ceylon Fisheries Research station initiated the first systematic survey of the island's coastal waters for seaweeds with a view to utilizing those of economic importance. These investigations (Durairatnam, 1961) revealed that there were many species of algae on the west coast, but very few on the east coast (Fig. 1). The most common seaweeds found in Sri Lanka are the brown seaweeds belonging to the genus Sargassum. They grow on rocks and other soiled objects but easily break loose from their attachment during heavy monsoons and are washed ashore. Some float about in the ocean in large masses. Extensive beds of seaweeds are found in Jaffna, Palk Strait, Gulf of Mannar, Pearl bank off Silarathurai and along the southwest coast of Sri Lanka extending from Ambalangoda to Galle. The extent of the beds and intensity of growth diminish progressively from north to south along the west coast.
Duraitarnam and Medcof (1955) discovered two species of seaweeds, Gracilaria edulis and G. verrucosa, known as Ceylon moss. Large quantities of these seaweeds were found in Kalpitiya, Trincomalee and Mannar (Fig. 2).
2. Gracilaria spp. and its utilization
Gracilaria spp. have been exported from Sri Lanka since 1800s (Duraitarnam, 1933). Exports to England of dried bleached “Ceylon moss” (Gracilaria spp.) was some 5,700 lbs in 1831 and 15,000 lbs in 1840 where it was sold at 09 d/lbs. In 1930's Ceylon moss was reported from Gulf of Mannar, Puttalan Lagoon (Fig. 2) and from Ponparippu to Kallar (Deraniyagala, 1933). During that period people gathered it by means of hooks attached to lines. Seaweeds were dried in the sun and left overnight in the dew which is said to bleach it more effectively than the sun.
The Government of Sri Lanka was not represented at the Workshop. This status report was kindly prepared by mrs Jayasuriya, whose contribution is hereby gratefully acknowledged.
Figure 1. The distribution of commercially important seaweed beds in the southern coast of Sri Lanka.
Figure 2. Locations where seaweeds are collected for commercial purposes.
During 1941 to 1944 it was estimated that 20,000 lbs of seaweed was exported to India annually. After the war this export trade ceased but a few people in those areas continued to collect, bleach and supply small quantities to the local market. In 1950's export of Gracilaria picked up again because of the strong demand from Japan.
In late 1960's due to a drop in quality standards of Sri Lanka Gracilaria exports, mostly due to the deliberate adulteration of the product, the trade was stopped for some time. In the 1970's about 50 to 100 tons of dried Gracilaria were again exported from Sri Lanka annually. The quantity exported in 1972 was around 50 tons. This increased to 100 tons in 1986.
At present the Gracilaria industry is geared to the export of dried product without any processing. The fishermen living in Kalpitiya and Trincomalee areas are mainly involved in collecting Gracilaria. Seaweed collection starts when orders are received from the local agents who represent export companies based in Colombo. Two collectors can collect a boatload of fresh seaweed weighing around 200 kg, or 30 kg when dried. The collected seaweed is unloaded on the beach and sundried for 4–5 days. Even though some cleaning is done by the collectors during sundrying, further cleaning is carried out at the purchasing centers. Here the weeds are sifted through a wire mesh sieve to remove foreign matter such as sand and seashells. The dried weed is further cleaned by the exporters prior to baling for shipment.
A very small percentage of the dried weed is sold locally. Retail packs, weighing 50 or 100 g are sold at most supermarkets, pharmacies and groceries in Colombo and suburbs. According to most Colombo traders, packeted Gracilaria is a “slow moving” item except during the Islamic festive season, when there is a good demand for the seaweed. Most people use it to make a drink or jelly.
Gracilaria is a popular item of food among fishermen in producer areas. A recent socio-economic survey (Jayasuriya, 1987) revealed that 9 out of 10 people living in the Puttalan Lagoon area use Gracilaria for domestic consumption. The most popular preparation is a porridge of this seaweed. The dried weed is washed several times and cooked in water for 5–20 minutes and the thick soup obtained is sieved using a cloth strainer. Coconut cream and lime are added to taste. The villagers believe this porridge to be highly nutritious and is considered an essential item during the fasting season.
Seaweed “jelly cube” is another common food in this area. Seaweed is washed several times until it becomes light in colour and is cooked in a little water with some lime juice sieved through a cloth strainer. Sugar, vanilla and colouring are added to the syrupy mass obtained which is then allowed to set for about an hour to a jelly like mass. The jelly is then cut into cubes.
3. Sargassum and its utilization
In Sri Lanka interest in brown seaweeds grew in the 1960's. Sargassum is the most economically important species of brown seaweed found in Sri Lanka. In addition to Sargassum several other species such as Laminaria, Macrocystis, Turbinaria, Fucus, and Ascophyllum which are found in Sri Lanka are rich in alginates. However, only sargassum species are found in quantities adequate to sustain commercial exploitation.
The first quantitative survey of Sargassum was carried out in 1966 in the southwest coast by Durairatnam (1966) (Table 1). The survey revealed that some 800 tons of the seaweed could be harvested from the coast. During this survey the following species of Sargassum and allied genera were identified:
Sargassum cervicone (Grev) Grun.
Sargassum cristaefolium
Sargassum cinereum J. Ag.
Sargassum ilicifolium (Turn) J. Ag. forma.
Sargassum swartzii (Grov.)
Sargassum tenerrimum J. Ag.
Turbinaria orriata J. Ag.
Cystophyllum muricatum (Turn) J. Ag.
The first two species were found between Ambalangoda and Galle while the others were found between Mannar and Jaffna. The dominant species in the southern coast is Sargassum cervicone.
The main economic use of brown algae is the production of alginic acid. The main use of alginic acid in Sri Lanka is in the textile industry.
The first attempt at alginic acid extraction was carried out in the late 1960's by the District Development Councils. Several collecting centres were set up at Hikkaduwa on the southern coast to collect Sargassum. The collectors, mainly fishermen, were paid US$ 0.05 per pound and district development councils sold it at US$ 0.07 to the National Textile Corporation which processed the raw material. Machinery were installed at one of the textile factories and processing was about to start when the scheme was abandoned by the corporation as a result of the dissolution of the District Development Councils. Samples were sent to many foreign companies to explore the export market for the dried seaweed, with no success.
In 1973, the Industrial Development board of Sri Lanka started a pilot project to produce liquid sodium alginate. The product was meant to be used by the National Textile Corporation as a mordant in dyes for textile finishing. The total investment and cost for this project was estimated and the annual production of alginic acid was placed at around 3000 kg.
This project had to be abandoned due to the limited availability of natural stocks of raw material, Sargassum cervicone, and difficulty in finding the required quantities of the weed in shallow areas. This weed is generally found in deeper areas of the reef.
During the 1960–70 period several pilot scale operations were undertaken to examine the feasibility of extracting alginic acid from local seaweeds. Locally manufactured alginic acid were found to be of international standard. Arumugam et al., (1981) found a distinct seasonal variation of alginic acid content in 12 species of brown algae from the northern part of Sri Lanka (Table 2).
| Location | Distance from shore (m) | Area of Estimation in m2 | Estimated weight kg/m2 | Estimate weight kg | Estimated weight (MT) | |
| Ambalangoda | -- | -- | -- | -- | -- | |
| Hikkaduwa | 1. | ( 0– 50) | 32,500 | 3.87 | 125,760 | 124 |
| 2. | ( 50–100) | 32,500 | 2.82 | 91,650 | 90 | |
| 3. | (100–400) | 195,000 | 0.55 | 107,250 | 105 | |
| Galle | 1. | ( 0–50) | 2,500 | 9.44 | 23,600 | 23 |
| 2. | ( 50–100) | -- | -- | -- | ||
| 3. | ( > -100) | -- | -- | -- | ||
| Dalwatta & Unawatuna | 1. | ( 0– 50) | 7,500 | 7.96 | 59,000 | 59 |
| 2. | ( 50–100) | 7,500 | 0.40 | 3,000 | 3 | |
| 3. | ( > -100) | -- | -- | -- | ||
| Habaraduwa | 1. | ( 0– 50) | 7,500 | 8.48 | 63,600 | 62 |
| 2. | ( 50–100) | -- | -- | -- | ||
| 3. | ( --- ) | -- | -- | -- | ||
| Koggala | 1. | ( 0– 50) | 25,000 | 6.52 | 162,900 | 160 |
| 2. | ( 50-100) | 25,000 | 0.92 | 23,000 | 23 | |
| 3. | ( > -100) | -- | -- | -- | ||
| Arangawala | 1. | ( 0– 50) | 10,000 | 6.20 | 62,000 | 61 |
| 2. | ( 50– 100) | 10,000 | 0.56 | 5,600 | 6 | |
| 3. | ( >-100) | -- | -- | -- | ||
| Hambantota | 1. | ( 0– 50) | 12,500 | 4.77 | 59,625 | 59 |
| 2. | ( 50–100) | -- | -- | -- | ||
| 3. | ( > -100) | -- | -- | -- | ||
| TOTAL | 755 | |||||
Source: Durairatnam (1966).
At present Sargassum-based products are not manufactured in Sri Lanka in spite of the availability of fairly large quantities of the weed.
4. Culture of Seaweeds
Cultivation of seaweeds is still in the experimental stage in Sri Lanka. More attention has been given to Gracilaria species which faces a severe threat of exploitation due to the high demand for export. Indiscriminate harvesting of Gracilaria could lead to the complete extinction of the resources in the country. Sivapalan (1975) conducted some experimental culture of Gracilaria edulis in Puttalam lagoon. He used the vegetative fragmentation method to culture this seaweed.
| Species | October 77 | December 77 | January 78 | March 78 | May 78 | July 78 | August 78 |
| Padina | 9% | 9% | 4% | 9% | 14% | 14% | - |
| Dictyota | 11% | - | 15% | - | - | - | - |
| Stoechospermum | - | - | - | - | - | 15% | 8% |
| Cystoseria | - | 19% | 15% | 25% | 32% | 30% | 17% |
| Cystophyllum | 15% | 10% | 11% | 18% | - | 10% | 10% |
| Turbinaria coinoides | 26% | 20% | 12% | - | - | - | 8% |
| Turbinaria orriata | - | - | 6% | 18% | 20% | 28% | 9% |
| Hydroclathrus | - | - | 13% | - | - | - | - |
| Sargassum polycystum | 20% | 14% | 12% | - | 22% | 26% | - |
| Sargassum whighti | 15% | 12% | - | - | - | - | 11% |
| Sargassum cervicone | - | - | - | - | - | - | 13% |
| Sargassum | - | - | 15% | 22% | 29% | - | - |
(-) = Species not absent. Source: Arumugam et al., (1981).
Sivapalan and Theivendirajal (1985) carried out experimental culture trials of the same species in one of the lagoons in the northern part of Sri Lanka. Vegetative propagation techniques were tried in these experiments and it was found that the plants grew to a length of 12 cm in 8 weeks.
Recently, the Bay of Bengal Programme of the FAO has launched a project on culture of Gracilaria edulis in one of the lagoons in Sri Lanka to start with experimental cultures that will hopefully lead to commercialization. So far successful trials have been carried out by using vegetative fragmentation as well as by spore setting techniques. Plants cultured by using spore setting techniques carried out in these waters attained a length of 30 cm in four months averaging 0.25 cm per day (Jayasuriya, 1989).
It was revealed that the fluctuations of environmental factors such as salinity, water current, tides and available nutrients of the surrounding water would affect drastically the growth of Gracilaria plants. Therefore, it is clear that more attention should be given to find suitable sites before expanding to commercial culture.
References
Arumugam, I., A. Siripala and K. Thivendirarajah, 1981. Preliminary studies on the alginic acid and agar contents of some marine algae. Proc. of the 37th Ann. Sec. of SLAAS.
Barton, E.S., 1903. List of marine algae collected by Prof. Herdman at Ceylon in 1902, with a note on the fructification of Halimeda. Herdman Ref. on Ceylon Pearl Fishery Part 1: 168–169.
Boergensen, F., 1936. Some marine algae from Ceylon. Ceylon. J. Sci. 12,2: 57:96.
Deraniyalaga, P.E.P., 1933. Cures marine products of Ceylon. Ceylon J. Sci. Sec. C. 5:73:74.
Durairatnam, M. and J.C. Medcof, 1955. Ceylon moss - a marine resource. Fish. Res. Stn. Ceylon, 16(2): 19–28.
Durairatnam, M., 1963. Some marine algae from Ceylon 2. Laurencia lamourous. Bull. Fish. Res. Stn. Ceylon, 16 (2): 19–28.
Durairatnam, M., 1961. Contribution to the study of marine algae of Ceylon. Bull. Fish. Res. Stn. Ceylon, No. 10: 5–117.
Harvey, W.H., 1853. Short characters of three new algae from the shores of Ceylon. Hooker's J. Bot. 6, (London).
Jayasuriya, P.M.A., 1987. The socio economic aspects of the people traditionally involved in the harvesting of wild Gracilaria lichenoides (Seaweeds) from Puttalam lagoon. Proc. 42nd Ann. Sec. SLAAS, Sec. F.
Jayasuriya, P.M.A., 1989. Preliminary observations on the culture of Gracilaria edulis using setting techniques (Proc. of the seminar on utilization and production of Gracilaria held in Songhkla 23–27 Oct. 1989).
Sivapalan, A., 1975. Cultivation of Gracilaria lichenoides in Puttalam lagoon. Bull. Fish. Res. Stn. Sri Lanka (26) 122:1–4.
Sivapalan, A. and K. Theivendirarajah, 1985. Studies on agarophyte, Gracilaria edulis. Experimental field cultivation and methods of improving yield and quality of agar.
Sevedelius, N., 1906a. Ecological and systematic studies of the Ceylon species of Caulerpa. Ceylon Mr. Biol. Lab. Rep. No. 4: 81–143.
Anant Saraya
Vithya Srimanobhas
Senior Fishery Biologist
Brackishwater Fisheries Division
Department of Fisheries
Fishery Biologist
Marine Fisheries Division
Department of Fisheries
1. Background Information
Several institutions, including Kasetsart University, Srinakarinwirot University, and the Department of Fisheries, have been working together on Gracilaria culture and processing, especially after the launching of the Agriculture Technology Transfer Project with USAID assistance in 1986. While some countries in the Asia-Pacific Region have a long history of research, cultivation and utilization of seaweeds, Thailand started to step into this field only a few years ago. In 1982, Edwards et al., reported the situation on a potential of the seaweed industry in Thailand. Gracilaria, Hypnea, Porphyra, Acanthophora, Caulerpa and some Sargassum were recorded as seaweeds of commercial importance in Thai waters. In the same year, Tam and Edwards also studied the agar quality of 25 Gracilaria samples collected from six provinces. Lewmanomont (1978) reported a total of 26 species of edible algae in Thailand, of which few are freshwater species and the rest marine.
2. Present Situation
At present research and development activities on the seaweed industry is emphasized in order to more fully understand the dynamics of relationship among marine plants, food security and nutrition. The Government of Thailand has realized that a seaweed project can promote food security and better nutrition.
Although there are many useful species of seaweeds available in Thai waters, only some species of Gracilaria and Polycavernosa are suitable for cultivation. Recently specimens of these agarophytes collected from coastal waters in Thailand were sent to Dr. Abbott for identification. The result (Abbott, 1987) showed that there are 8 species belonging to Gracilaria and Polycavernosa as follows:
Gracilaria tenuistipitata var. liui
G. firma
G. irregularis
G. saricornia
Polycavernosa changii
P. fisheri
P. fastigiata
P. percurrens
The coastal inhabitants in 23 provinces along the east and west coastlines stretching some 2,600 kilometers, have utilized several species of seaweed as direct food or fertilizer. Gracilaria is one of the important seaweeds used for human food and source of agar. Other edible species are utilized as supplementary food in small quantity.
The latest annual statistics show that 203.4 tons “seaweed” were exported in 1980 (Table 1), the bulk of it going to Germany. The fluctuation in the yearly quantities from 1980 to 1987 was due to the needs of markets, availability of seaweeds, and other factors. However, the figures might have included the product of “Spirulina” as well. Thailand also exports agar in the form of instant agar (Table 2) by repacking after adding different kinds of flavors to the imported food grade agar. Agar was exported mostly to America. Some were shipped to Australia, Canada, France, England and Germany. The highest recorded yearly export was about 12 tons in 1985 and 1986.
The growers and traders in Pattani Province have reported that dried Gracilaria is exported to Malaysia at some 5 tons annually. The product is harvested mostly from small culture ponds.
Importation
Generally, Thailand imports both raw and processed seaweed products. Different forms of the products such as dried and processed Porphyra, Kombu, Wakame, etc. are imported as food. Table 3, shows the quantity of seaweed products imported; it included 78 tons in 1989, mostly from Japan, China and Korea. Sodium alginate and alginic acid have been imported for different industrial uses (Table 4 and 5). Among the imported product forms, “agar” ranks the highest, which is about 300 tons of mostly food grade agar from Chile, Japan, Taiwan and Korea.
Culture Status
Micro-algae have been cultured for quite sometime as food for freshwater and marine animals. However, macroalgae culture particularly Gracilaria started only a few year ago. Pond culture of Gracilaria is being carried on in Pattani province, with unofficial records on production and area. Other methods of cultivation such as long-lines, nets, and sporeling rope are being tested.
| Year | SW (tons) | US$ (10,000) |
| 1979 | 79.2 | 43.2 |
| 1980 | 203.4 | 50.9 |
| 1981 | 154.7 | 65.6 |
| 1982 | 68.0 | 83.9 |
| 1983 | 60.1 | 80.5 |
| 1984 | 68.8 | 102.5 |
| 1985 | 101.0 | 155.5 |
| 1986 | 102.4 | 141.5 |
| 1987 | 94.0 | 116.9 |
| 1988 | 103.4 | 116.9 |
| 1989 | 115.4 | 118.2 |
| Year | Agar (mt) | US$ (10,000) |
| 1984 | 1.2 | 0.3 |
| 1985 | 11.8 | 8.2 |
| 1986 | 11.7 | 8.5 |
| 1987 | 10.8 | 10.7 |
| 1988 | 5.1 | 3.9 |
| 1989 | 3.0 | 3.3 |
| Year | SW (mt) | US$ (10,000) |
| 1979 | 15.6 | 9.0 |
| 1980 | 11.2 | 9.1 |
| 1981 | 18.3 | 10.7 |
| 1982 | 9.2 | 8.1 |
| 1983 | 20.2 | 12.6 |
| 1984 | 34.7 | 24.3 |
| 1985 | 17.2 | 16.9 |
| 1986 | 50.0 | 48.8 |
| 1987 | 35.7 | 37.1 |
| 1988 | 47.2 | 70.9 |
| 1989 | 78.1 | 105.6 |
| Year | Algin (mt) | US$ (10,000) |
| 1979 | 154.0 | 45.8 |
| 1980 | 178.3 | 53.6 |
| 1981 | 99.2 | 30.8 |
| 1982 | 77.9 | 22.9 |
| 1983 | 233.1 | 56.7 |
| 1984 | 123.5 | 34.8 |
| 1985 | 135.4 | 52.7 |
| 1986 | 195.6 | 62.0 |
| 1987 | 220.6 | 64.8 |
| 1988 | 329.1 | 148.7 |
| 1989 | 316.4 | 212.9 |
| Year | Agar (mt) | US$ (10,000) |
| 1979 | 255.3 | 269.9 |
| 1980 | 208.6 | 273.7 |
| 1981 | 184.1 | 246.6 |
| 1982 | 230.1 | 286.5 |
| 1983 | 307.0 | 405.1 |
| 1984 | 259.9 | 351.9 |
| 1985 | 234.1 | 381.3 |
| 1986 | 251.9 | 433.0 |
| 1987 | 276.8 | 451.7 |
| 1988 | 262.4 | 444.4 |
| 1989 | 274.8 | 517.6 |
In terms of culture area, the sites include lagoons and coastal areas, which are also suitable for shrimp culture. In this connection, these two culture species are being compared in terms of investment and returns. Thus it has not been easy to convince people to use the coastal zone for Gracilaria culture. However, shrimp culture in certain areas has met some problems related to environmental issues, i.e. drained waters causing pollution. Abandoned shrimp ponds can probably be utilized for Gracilaria culture.
Thailand has many islands where the reef flats and rocky shores are suitable for Eucheuma cultivation. The Government plans to introduce this and other possible species for culture. The government also supports the seaweed processing industry; an agar processing pilot plant has been in operation and under the responsibility of the Biopolymer Research Unit of Srinakarinwirot University.
3. Economic Species
Lewmanomont (1978) and Edwards et al., (1982) have listed several economic species found in Thai waters, as follows:
| Gracilaria spp. | P. gymnospora |
| Hypnea spp. | P. distromatica |
| Porphyra vietnamensis | Dictyota dichotoma |
| P. crispata | Hydroclathrus clathretus |
| Acanthophora spicifera | Turbinaria spp. |
| Sargassum spp. | Chaetomorpha antennina |
| Caulerpa spp. | Codium sp. |
| Laurencia obtusa | Enteromorpha spp. |
| L. papillosa | Monostroma sp. |
| Gelidium spp. | Bostrychia radicaus |
| Padina australis | Catenella nipae |
| Halymenia durvellaei | Bangia fusco-purpurea |
The above species are usually gathered from natural stocks and used fresh as salad. At present, research and development activities are concentrated on Gracilaria culture and processing. Eucheuma is a possible species to be introduced for culture.
4. Production Statistics
As Thailand has only recently gone into seaweed culture, there are no official records of the production statistics, both from culture and gathering.
5. Production Systems
Regarding production systems, only one small village in Pattani province is culturing Gracilaria on a very small scale. Seeding is by broadcasting thalli into approximately 400 m2 earth ponds located in or near the mangrove forest and allowed to grow naturally. There is a small sluice gate to keep the pond water at about 60–80 cm deep during low tide. Local farmers have reported that the production is about 7 tons (dried) per hectare per year.
Information on Spirulina, the freshwater micro-algae which is produced for fish or shrimp food, is limited. Most of the production is by private companies.
6. Economics of Production
The culture of Gracilaria in Thailand is at present based on family labour. The labour costs depend on the members of the family and there has been no documentation or economic evaluation of this practice. Seedlings for vegetative propagation are collected from the wild stock.
Although there are several potential Gracilaria culture methods being tested, only pond culture has produced satisfactory yields. Present coastal land use emphasizes the cultivation of shrimp so that it may not be feasible to build new ponds on a large-scale solely for the culture of Gracilaria. However, the abandoned shrimp ponds could be used for Gracilaria culture.
As to the production from the gathering and from pond culture in southern Thailand, the precise quantity leaving Thailand for Malaysia is unknown but estimated to range from 30–50 tons annually valued at 1.8–3.0 million Baht (Hollenbeck, 1987).
7. Processing and Utilization
Agar is the only important seaweed product being developed at present. There are eight agarophyte species recognized in Thailand. Agar yield, gel strength, gelling and melting temperature, ash, sulfate and 3–6-anhydrogalactose content from these agarophyte have been determined by Biopolymer Research Unit (BRU) of Srinakarinwirot University. Different grades of extracted agar, low-grade, food-grade and bacteriological-grade agars have been tested for various industrial purposes. The results are satisfactory. Carrageenan from Hypnea is another seaweed product being studied. BRU is also processing alginate from several species of brown algae. However, the status of processing, as already mentioned, is only at the experimental or pilot stages.
There is no seaweed processing plant in Thailand yet, so that agar and algin are imported for different industrial purposes. Ministerial Act No. 1399 (1988) has set the standards of agar, as follows:
Arsenic, ppm. less than 3
8. Marketing of Seaweed Industry
Fishermen of Pattani province collect growing Gracilaria from ponds while the seabass farmers of Satul and Songkhla provinces harvest the natural growth of Gracilaria on the cages of fish and other substrates. This seaweed product provides supplementary income. The middlemen collect the dried materials from fishermen and sell them to exporters. Only a small quantity is sold fresh at the local market for local consumption.
Malaysia is the only country that fishermen in the southern provinces have reported as the importing country of dried Gracilaria. Other seaweed products such as repacked flavor agars and Spirulina tablets are exported to Japan, America, Australia, Canada, England, France and Germany (Tables 1 and 2).
9. Problems and Needs
In order to develop the seaweed industry, the following problems and needs should be clarified and followed up.
Good data on yields from both culture and natural stocks must be obtained.
Profitability of the prevailing small-scale culture systems using family labour should be determined.
Post-harvest technology must be developed in order to improve the price of dried materials and agar quality.
Import and export statistics must be recorded clearly in terms of kind of products, sources and other relevant items.
Conservation of the natural growing beds of certain economic seaweeds should be emphasized and developed.
Income from Gracilaria culture is small compared to shrimp culture, so that fishermen or fishfarmers are not so interested in cultivating the seaweed.
Government also needs to conduct Eucheuma research and development at the laboratory level.
10. Research and Development
Research and technological development activities are being undertaken by the following institutions:
Kasetsart University Faculty of Fisheries, on the biology of Gracilaria and Polycavernosa. Culture experiments have been set up at various locations both in ponds and out planting in nearshore areas.
Srinakarinwirot University Faculty of Science, with pilot studies on processing. Different grades of agars have been extracted from Gracilaria by several methods. Trials on the extraction of agarose, carrageenan and pigment found in red algae are satisfactory.
King Mongkut Institute of Technology at Thonburi, at providing the technical support to the design of a seaweed processing plant.
The Department of Fisheries, on research and development on both culture and processing of any economic seaweeds. At present there are few trained personnel on seaweed culture and processing. The government needs the technology on both culture and processing of certain economic seaweeds. It is keen on information exchange at the sub-regional level to hasten the development of locally suitable technology.
References
Edwards, P., S. Boromthanarat and D.M. Tam. Seaweeds of Economic Importance in Thailand Part 1, Field Survey, 1982 Thai Government Statistics and Future Prospects. Botanica Marina Vol. XXV, pp. 237–246.
Hollenbeck, L. Economics and marketing summary of Gracilaria in Thailand. Proceeding of the final project Conference 1987 Vol. II, 13–14 August 1987, Agricultural Technology Transfer Project, Bangkok.
Lewmanomont, K. Some edible algae of Thailand. Technical 1978 paper, Faculty of Fisheries, Kasetsart University.
Tam, D.M. and P. Edwards. Seaweed importance in Thailand Part 2, Analysis of Agar from Gracilaria. Botanica Marina, 1982 Vol. XXV, pp. 459–465.
Algal harvests in Thailand
Algae imported into Thailand
Agar-agar imported into Thailand
Algin imported into Thailand
Algae exported from Thailand
Agar-agar exported from Thailand
Do Van Khuong
Department of Seaweeds
Institute of Marine Products Research
Haiphong, Vietnam
1. Seaweed Resources of Vietnam
There are more than 639 species of seaweed in Vietnam, distributed in different ecological zones as follows:
In the high littoral zone with a rock and stone substrate: Dermonema,
Gelidium, Catenella, and Gloiopeltis.
In the medium littoral zone: Enteromorpha, Chaetomorpha, Colpomenia,
Gymnogongrus and Pterocladia. In the lower littoral zone are:
Sargassum, Hypnea, Padina and Dictyota.
In littorals with soft substrate consisted of mud, mud-sand and sand-mud. Common species in this areas are Caulerpa, Cladophora, Ectocarpus and Dilophus. There is no seaweed in areas where the soil consists of pure sand or mud.
In brackishwater ponds. Common species in these ponds are Gracilaria, Cladophora, Chaetomorpha and Polysiphonia.
In salt fields. Where water is stocked, the common species are Acanthophora, Gracilaria and Cladophora.
Main commercial species of seaweed in Vietnam are the following:
Gracilaria (RONG CAU): There are about 16 species of Gracilaria distributed along the coastal region, including estuaries, brackishwater pond, canals of salt fields, mollusc beds, around mangroves or even on mud surfaces. In natural condition, Gracilaria verrucosa gives high productivity (maximum natural biomass from 1 to 1.5 kg/m2). Production of natural stocks of Gracilaria in Vietnam is some 9300 mt (wet weight), out of which Gracilaria verrucosa contributes 7600 mt.
Sargassum (RONG MO): 44 species. Of these, S. siliquosum, S. maclurei, S. herklotsii and S. carpophyllum h are the main species. Estimated biomass of Sargassum in Vietnam is 30,000 mt (wet weight).
2. Status of Seaweed Production and Processing
Seaweed culture and processing in Vietnam is becoming an important industry. Since 1987, annual yield of Gracilaria has been about 700–800 MT (dried weight), of which 100–150 MT is used for agar-agar processing or for foodstuffs. The rest is exported to Asian countries. Sargassum is harvested from natural stocks for processing alginate.
In 1987, Vietnam only produced 10 MT food agar. In the last two years several agar factories were built to meet the market demand. The total annual production of agar has increased to over 20 MT/year.
Natural biomass of Sargassum is not fully utilized, only about 100 MT/year (dried weight) are harvested and used as manure, and seaweed meal for different purposes.
The alginate industry has not been developed. Annual productivity of alginate is about 15–20 MT (paste form). It is still far from meeting the needs of the textile industry. At present Vietnam imports alginate from India. Studies on Gracilaria culture and processing techniques have been carried out since 1963, but its commercial culture initiated in 1980. In general, levels of technology and productivity are low. Dried product of Gracilaria from culture was 250–300 MT in 1989 (1/3 of total annual production). Growing area for Gracilaria is around 350 ha. The potential area for Gracilaria farming is more than 10,000 ha in the north and central Vietnam.
Gracilaria growing method being practiced is bottom culture using vegetative reproduction type. The method has 3 forms:
| Type 1: | In the big pond/swamp with gates and additional seeds, small quantity of manure and control of undesirable species. Productivity is about 1 MT/ha/year (dried product). |
| Type 2: | No additional seeding and no manure is applied. This is a form of natural harvest of Gracilaria with naturally recruited fish/shrimp. Productivity is 0.5 MT/ha/year (dried product). |
| Type 3: | In small ponds with technical advantages, reasonable amount of manure applied, increased water exchange in tidal periods. Productivity of this type is above 2–3 MT/ha/year (dried product). The growing area applying this type is still limited. |
Technique of raft culture using spore is still at the testing stage.
Since 1963 there have been many studies on G. verrucosa and agar processing. Research was done in the following stages:
From 1963 to 1973: “General studies on natural resources of Gracilaria verrucosa and its experimental culture”. This was a cooperation programme between Vietnam and the Democratic Republic of Germany, dealing with 5 scientific research units.
From 1973–1977: Studies on G. verrucosa growing to provide raw material for agar processing. This was conducted by the Institute of Marine Products Research and G.D.R.
After that, researches have been carried out focused on the establishment of models for production activities.
In 1988 a joint laboratory was established in Haiphong City and operated by the Institute of Marine Products Research (SRV) and Institute of Fishery and Pacific Ocean Research (Vladivostok, USSR). Initial good results of this laboratory have been achieved.
The Ministry of Fisheries has set the following targets: By 1990 there should be some 1,900 ha of culture area; dried product of Gracilaria 2000 MT; and agar product 100 MT. By 1995: 3000 ha, 4000–5000 MT, and 6000 MT, respectively.
3. Commercial Seaweed Species
Available data show there are several commercial seaweed species in Vietnam which belong to important genera as follows:
| - | Gracilaria | 16 | species |
| - | Gelidium | 7 | " |
| - | Gigartina | 4 | " |
| - | Pterocladia | 2 | " |
| - | Sargassum | 44 | " |
| - | Porphyra | 1 | " |
| - | Ulva | 1 | " |
| - | Caloglossa | 1 | " |
| - | Codium | 1 | " |
| - | Hydroclathrus | 1 | " |
Important species for seaweed culture include:
S. carpophyllum
Other species having good potential for culture and gathering are:
Acanthophora spicifera
4. Production Statistics
| Name of Species | Cultured | Gathered | ||||
| Qty (MT) | Value (MD) | Area (Ha) | Qty (MT) | Value (MD) | Estd. Area (Ha) | |
| Red Seaweed | ||||||
| Gracilaria | 300 | 1050 | 350 | |||
| verrucosa | ||||||
| G. blodgetti | 600 | 1800 | 3000 | |||
| Other G. species | ||||||
| Brown Seaweed | ||||||
| Sargassum siliquosum | ||||||
| S. maclurei | 100 | 3.5 | ||||
| Other S. species | ||||||
| Green algae | ||||||
| Ulva conglobata | Used as vegetable, no data | |||||
| Micro Algae | ||||||
| Spirulina | Some cultivation, but no data available. | |||||
| Diatoms | Used as live food for larvae of shrimps. | |||||
| Culture density is over 1,000,000 cells/ml. | ||||||
| Name of species | Consumed Locally | Exported | ||||||||
| F | SP | P | SP | P | ||||||
| Qty (MT) | Value (MD) | Qty (MT) | Value (MD) | Qty (MT) | Value (MD) | Qty (MT) | Value (MD) | Qty (MT) | Value (MD) | |
| Gracilaria | ||||||||||
| Fresh vegetable | No data | |||||||||
| Dried | 150 | 425 | 750 | 600,000 | ||||||
| Meal | 20 | 1000 | ||||||||
| Agar | ||||||||||
| Sargassum | ||||||||||
| Fresh | No data | |||||||||
| Dried | 100 | 3.5 | 15 | 22.5 | ||||||
| Sodium alginate | ||||||||||
| Spirulina | ||||||||||
| Dried | No data available | |||||||||
| Transformed to pellet | ||||||||||
F = Fresh, SP = Semi-processed, P = Processed
| Product form | Qty (MT) | Value (US$) | Country of Origin |
| Agar | Exact figures not available | India | |
| Alginate | |||
| Carrageenan | |||
5. Methods of Seaweed Growing in Vietnam
The small family-scale of farming is most popular. Operating area of this scale is about a hundred square meters to 1–2 ha. From 15° latitude to North, this scale is operating everywhere. Recently, some cooperatives have begun to operate areas of 10–50 ha. Some state enterprises operate more than 50 ha or as much as 100 ha in Hue (Central Vietnam), where the UNDP/FAO assisted Seaweed Project VIE/86/010 is located.
There are two farms culturing Spirulina maxima. One is a nitrogen fertilizer factory in the North operating an area of 1000 m2. The other is in mineral stream of the south. Diatom culture (Chaetoceros spp., Skeletonema costatum) is done mostly in shrimp hatcheries. Scale of diatom culture depends on scale of shrimp hatchery. At present, shrimp hatcheries can keep diatom all year round to guarantee supply of stock for hatcheries at any time. There are 3 types of growing techniques:
Extensive Culture
This type is applied in a big pond of 5–20 ha. There is no or little seeding, thus, seed from wild is main source. There is no fertilization or water change. Management depends on collection of fish/shrimp seed and their natural culture in ponds. Seaweed is harvested 2–3 times/year. Productivity is not over 0.5 MT of dried product/year/ha.
Semi-Intensive Culture
This is applied in ponds of 1–5 ha. Pond bottom is treated before operating. Seed is supplied with 200–300 g/m2. Fertilizer is applied in small quantity. Water change and foreign seaweed control are done. Productivity of this type is 1 MT/ha/year (dried product). Farmers add seeds of shrimp and fish to increase economic returns.
Intensive Culture
This type is applied in small ponds of 0.5–1 ha. Seaweed ponds are built in brackish swamp area with a total area of 10–15 ha. These ponds are equipped with systems to let in sea and fresh water. With both water sources, control of salinity and foreign seaweed in pond is convenient. That is why intensive culture is connected closely with design building, cleaning and repair of ponds. Procedure of growing technique is strict. Productivity of this growing type is 2–3 mt/ha/year (dried product), which could be further increased.
The commonly used Gracilaria growing technique includes the following steps:
Site selection: Site should be near sources of both sea and fresh water. Salinity of seawater is above 8–30 ppt. Pond bottom is mud, sand-mud or mud-sand; soil pH is 7.0–8.6.
Pond construction: Pond bottom level is at 0 level of sea chart. Pond area is 0.3 to 1.0 ha. Supply and drain gates are separated and depth of water pond is 0.7–1 m. Pond bottom should be treated.
Culture method: Use of organic manure. Before planting seeds are treated in solution of inorganic manure. Seed density is 500g/m2.
Pond management: In winter, water depth is maintained at 30–40 cm; in summer this level is raised 50–60 cm. Water change is done utilizing tidal cycle. After every water change, organic or in-organic manure is applied. Foreign seaweeds are removed regularly.
Harvesting: The first partial harvesting is done after 25–30 days of culture. The rest is retained with density of 500–700 g/m3. Management is continued until next harvest.
Red seaweeds collected from the wild are Gracilaria verrucosa, G. blodgettii, G. textorii, G. chorda and Catenella nipae. These species grow naturally in brackishwater ponds, salt fields and littoral regions.
Brown seaweed such as Sargassum siliquosum, S. maclurei, S. herklotsii and green seaweed, Ulva conglobata are growing in littoral regions.
Spirulina is cultured in cylindrical tanks. Natural mineral water having high content of bicarbonate and pH of 9–12 is used for culture. Nutrients are added into culture water. Sun energy is used for photosynthesis and wind is used to stir water in tanks.
Spirulina is also cultured in tank with zigzag water current. Waste water with high nitrogen content is used for culture. Some chemicals are added to make a suitable medium. Sun energy is used. Air compressor is used for aeration and generation of water currents.
6. Economic Effect
Recently, technicians of the Institute of Marine Product Research in Haiphong City, together with several companies and cooperatives, organized a workshop on the culture of seaweeds. It was reported that the benefits gained from different types of culture are as follows:
| Intensive | : about US$ 340 ha/year. |
| Semi-intensive | : about US$ 300 ha/year |
These two types of culture, used in family scale farming, gave the highest economic returns. Operation is simple, convenient and easy to manage.
7. Processing and Utilization
Agar processing was studied from 1963, but technology and productivity are still low. From 1974 to 1979 Vietnam and Democratic Republic of Germany cooperated to build a pilot plant with a capacity of 50 tons agar/year. From 1981 the pilot plant has been operated with an output of 20 MT/year. At present, we can design a factory and make facilities for production of agar up to 10 MT/year by both refrigeration and pressure methods.
Alginate extraction has been studied since 1984 using sargassum as raw material. In 1986 alginate production was 20 mt, mainly used for the textile industry. In the past two years, production of Sodium alginate has been decreasing.
Dried tablets of Spirulina are being produced and used as nutritious supplement for women after childbirth and under-nourished children.
List of seaweed processing factories:
• Agar processing units
HALONG Fish Processing Factory (Haiphong Fisheries Complex). Annual production: 10 Mt.
Research Institute of Marine Products in Haiphong. Annual production: 5 MT.
Centre of Seaweed Culture and Processing THUA THIEN HUE. Annual production: 5 MT.
Fish export processing factory HAIPHONG. Annual production: 5 MT.
Besides, there are several small agar processing units with annual production of 2–3 MT. They are situated in different parts of the country.
• Sodium alginate
HALONG Fish Processing Factory, HAIPHONG, annual production: 10 MT.
One unit in DANANG, two units in HOCHIMINH City, one in District Land, the other in THUDUC Polytechnical Institute (5 MT/year each).
Station of Utilization
In Vietnam, seaweed is used in different ways depending on quality and effect of each species. In the past Gracilaria is used to make gel (THACH), in beverage, and as feed in pig raising. Only a small portion was dried for producing agar. Gracilaria is now primarily processed for export and agar processing. A limited quantity of agar is used in food and medical industries. Sargassum is plenty and coastal people use it as manure. Some are dried and used as medicine to treat cough, basedo, diabetes, etc. Recently, some units have being using dried Sargassum to make Sodium alginate. For a long time the pharmaceutical industry has paid attention to seaweeds and has succeeded in extracting various types of medicinal substances from seaweeds such as Caloglossa leprieurii, Ulva conglobata, Sargassum, and Gracilaria.
Vietnam exports dried seaweed only (80% of production), agar is exported in small quantity.
Quality Standardization
The Ministry of Fisheries issued rules and Regulations for agar-agar production 58-QTN 38–77 and State Department of Standards and measurement issued quality standard of agar-agar TCVN 3591-88 with the following main points:
| Gel strength | : | 150–220 g/cm2 |
| Ash content | : | < 3% |
| Protein content | : | < 1% |
| Insoluble foreign matters | : | < 2% |
Agar-agar from smaller plants still have some disadvantages such as lower gel strength, high ash content and solubility problem. Studies done by the Research Institute of Marine Products HAIPHONG have improved the technology for agar-agar production. The new product has the following characteristics:
| Gel strength | : | 400–600 g/cm2 |
| Ash content | : | 1–1.5% |
| Dissolving time | : | < 30 minutes |
8. Market
Market of Gracilaria and agar is not well organized but follows a self-regulating mechanism. Buying of raw materials is not well-organized. The manufacturing process of agar factories is still not controlled strictly so that agar-agar is produced using different techniques resulting in varying qualities.
9. Problems and Requirements
For development of Gracilaria culture, it is necessary to adopt the following measures:
Observe strictly resource conservation measures to prevent Gracilaria from being over-exploited.
Select species of Gracilaria in order to obtain those with high productivity and good quality agar.
Through international cooperation, introduce commercial species of seaweed from countries having ecological conditions similar to Vietnam's.
Investigate natural conditions to determine the potential for seaweed culture development.
Improve techniques of growing seaweed with high productivity.
Test new growing techniques such as raft growing and polyculture techniques like seaweed with fish/shrimp culture.
Widen cooperation with international and regional programmes on the growing and processing of seaweed.
Introduce improved technologies of growing and processing to make good agar products that would meet domestic and foreign demands.
Build a centre for Gracilaria Seed Production in different ecological localities so that these can supply seed easily to farmers and teach them techniques to increase productivity.
Improve the techniques of Sargassum growing and alginate production.
On the basis of the law on investment, projects will be established to attract capital investment from foreign countries to set up seaweed farms and processing factories.
10. Research and Development Activities
The Research Institute of Marine Products HAIPHONG is responsible for cooperation with national and international organizations in seaweed research.
The Institute has achieved many important results that include technology of growing and processing seaweeds with high productivity, training of technicians and transfer of techniques to farmers. The Institute has collaborated closely with the Institute of Biology, Institute of Oceanography NHATRANG, State Center for Scientific Research, University of HANOI, and Pedagogical Institute of HANOI. The Institute cooperates with various other institutes in this field.
Seaweed scientists are trying to achieve the targets of developing 4000 ha for seaweed growing and producing 7,500 MT dried seaweed and 800 MT agar-agar/year by the year 2000.
Acknowledgement
The author of this report would like to thank Prof. Dr. Bui Dinh Chung, Director of the Research Institute of Marine Products in Haiphong, for his kindness in reading the manuscript and suggesting improvements.
RESEARCH PROPOSALS
ON SEAWEED CULTURE AND UTILIZATION IN VIETNAM (IN PRIORITY ORDER)
I. Research Proposals on Seaweeds Culture and Utilization in Vietnam for Consideration at the Workshop
Research on Seaweed Culture
Selection of high-productivity and good-quality strains within Gracilaria spp. for cultivation of Gracilaria verrucosa by bottom method.
Technology for sporophyte propagation and culture techniques for Gracilaria verrucosa cultivation by insertion line method using spores, aimed at the utilization of deep water areas like closed bays, lagoons, brackishwater canals, etc.
Measures for prevention and elimination of undesirable seaweed species in G. verrucosa culture lagoons and ponds.
Ecological conditions limiting productivity of G. verrucosa culture in different ecological areas of the country.
Technological improvement in intensive culture of G. verrucosa aimed at getting a yield of 4–5 tons of dried seaweed per hectare per year, in the forthcoming years.
Introduction of some seaweed species of high commercial value, experimental culture and studies on their adaptability.
Research on Processing and Utilization
Technological improvement in agar extraction process aimed at getting higher quality agar; studies on, or application of, technological progress in agar purification to produce high grade agar products.
Technological improvement in sodium alginate extraction from Sargassum for production of sodium alginate powder.
Preliminary studies on extraction of chromosomes and highly bioactive substances from seaweeds.
II. Needs of the Country
Adequate and timely information on seaweed markets.
Training of Vietnamese technicians in other countries and the possible reception by Vietnam of trainees from other countries of the region for practical work in Vietnam.
Assistance in regards to equipment, fund and expertise to enable the organization of regional and/or international workshop in Vietnam on seaweed production, processing and utilization in the forthcoming years.
Assistance in providing necessary equipment and facilities to produce some food products from seaweeds, e.g. from Gracilaria, Porphyra, Ulva, etc. and promoting their wider consumption among the people.
