The seaweeds of commerce are macroscopic algae. They, along with the other forms of algae, provide the base of the food chain for the reef and open sea organisms. Traditionally, seaweeds are categorized as “blue-greens”, “reds”, “greens” or “browns” based on their predominant or unique pigments. These groups can be referred to more formally as the phyla Cyanophyta, Rhodophyta, Chlorophyta and Phaeophyta, respectively.
Industrial interest in seaweeds is largely for the colloids, gels and gums that can be extracted from them. Seaweeds for industrial extraction are, but for their farming in the Philippines, from the harvesting of wild crops. In Japan, Korea and China there is, in addition, a very significant industry which farms seaweed for human food. In Japan such seaweeds have an annual value of over half a billion dollars (Fisheries Statistics of Japan, 1974) and are Japan's monetarily largest aquatic crop. Although interest in seaweeds as a direct source of human food is not as great in other countries, seaweed (mostly from farming) is the world's sixth largest aquatic crop (Pillay, 1976). Some 400 000 dry tons are being used per year (K. Nielsen, in press).
Currently, seaweed is exported from Southeast Asia largely for two categories of colloids, agars and carrageenans from red algae. There are several other as yet undeveloped possibilities for commercial use. Alginic acid from the brown seaweed Sargassum is one of them. These extractibles are apparently the ground material filling the space between the cellulosic fibrils in the cell walls. Often they are 30 to 50 percent of the salt-free dry weight of the seaweed; the salt, being largely potassium chloride, is itself saleable.
Carrageenans are highly sulphated poly-d-galactans. The three kinds in commercial use are lambda-, iota-, and kappa-carrageenan. The former two contain 30 to 40 percent sulfate. The latter two are the kinds obtained from Southeast Asia. Each is derived from a separate species complex within the genus Eucheuma. The two gels are very different from each other as well as from the iota- and kappa-carrageenans obtained from other genera. For example, the kappa-carrageenan obtained from the species exported under the name “cottonii” is an almost chemically ideal kappa-carrageenan, yet it cannot be used in all products where kappa-carrageenan from Chondrus, the North Atlantic “Irish moss”, is used. All kappa-carrageenans form brittle rigid gels that are warm water soluble. Iota-carrageenans come from species exported as “spinosum”. They are all cold water soluble and, unless modified chemically, do not form elastic rigid gels: their gels are rather like a syrup that only gets thick without becoming rigid. Most carrageenans wholesale from US$2.50 to US$4.50 per pound (US$5.90– $9.90/kg).
Agars are low-sulfate large modules formed mostly from poly-l-galactans and are of many kinds. The kinds are distinguished by their melting and gelling temperatures, by their degree of methylation into ionic and non-ionic forms, by the kinds of linkages between the galactose units and by the proportions of agro-pectin and agarose they contain. Bacteriological agars are generally non-ionic and have melting temperatures of over 85°C and gelling temperatures of 35 to 39°C. They are worth US$20 to US$30 per pound (US$44–$66/kg), retail, and about US$5 per gram. It can be 30 percent of the agar. The largest uses of agar are in such industries as meat canning.
For humans who eat them the algae have their values. These values are more likely to be in the provision of essential minor elements in the diet, and perhaps vitamins, rather than being sources of carbohydrates, fats or proteins. They do add variety and delicate flavours which Oriental peoples relish. Some Pacific island peoples, e.g. the Hawaiians, utilize some very strongly and uniquely flavoured seaweed as food. For example, Dictyopteris, which has cyclopropanes of which some attract brown algal male gametes, and Asparagopsis, which may be up to nearly 2 percent iodine by dry weight. The shoreside village fish and/or vegetable markets throughout the Region have a variety of seaweeds displayed for sale. Among the seaweeds, the Region's markets most often have Caulerpa and Gracilaria and, less frequently, Eucheuma, Pterocladia, Gelidiella or the seasonal Hydroclathrus. Caulerpa, Eucheuma and Hydroclathrus are used as green salad vegetables. The others, including Eucheuma, are used for their gels. The coarser Gracilaria species and Eucheuma, among others, are sometimes eaten pickled.
The coastal peoples of the South China Sea area (Cambodia, Hong Kong, Malaysia, Philippines, Singapore, Thailand, Vietnam) are generally believed to be increasing in numbers at rates exceeding the 2.5 percent per year generally stated as an average for the same countries. They are not characteristically land owners and do not have capital. One can expect their average per capita contribution to any nation's GNP to be at the low end for the respective country and this is often threatened with being lowered further relatively as the more efficient capital intensive development of land and fisheries in the area replaces reliance on the products of individual efforts. These people are largely at the mere subsistence level now, very independent, indigent, and without or with but a low level of education.
The harvests from the sea and land are being pressed to provide for the present small-island and coastal populations. Additional resources, as new materials or industries must be developed both for improvement of the standard of living of these people and to provide for their future increases in population. Otherwise in the future larger populations will have even less than now, and fall still further behind the overall populations in the South China Sea area. Providing this segment of a population alleviation from the resulting distress means introducing new sources of income. Such introductions are difficult, must not be pressed on the people, take time, and are generally of little interest to the citizenry with capital. However, seaweed farming, among the different possibilities, with its ultimate markets limited now as much as anything by reliable availability of the seaweed that would be produced, appears an ideal opportunity for peaceful socio-political and steady economic improvement of the lot of these coastal people of the area.
Historically the Region has been the main commercial source of carrageenan and agar algal gel materials; though Irish moss was used at the same time along the European coasts on a home-use basis. In the 1930's many new uses for these gels were developed, largely in the food industries. Since that time knowledge of the chemistry of algal gels has advanced greatly and, as this has taken place, the compliment of uses has broadened. Modern condensed milk, vulcanized rubber, smokeless powder, pellet-binders and ice cream rely on algal gels though much of the world's usage otherwise is in luxury products.
The increase in world seaweed trade volume averages about 20 percent per year. An actual value for the Region is hard to ascertain due to fluctuations in buyer policy, lack of stability in production and export, also significant increases in South American production may be making up for a general decline in production from some of the former major wild crop supplies. A confident estimate from FAO data (Naylor, 1976) is impossible. Production from the Region is probably increasing, however, but surely not more than 10 percent per year.
Aerial, on-site and chart studies as well as historical sources all indicate that the regional potential for seaweed farming is very large and far from having been realized. There are a few main reasons for the slow development of seaweed farming in the Region: the paucity of knowledge concerning the biology and the natural products of tropical seaweeds; the inefficient export system; and lack of production research and development.
The growth of seaweeds is so sensitive to environmental variations that a very fertile site may be but a few square metres in area. Even though a number of such areas may be closely associated, their farming by others than families hiring no help has succeeded only rarely. Success in farming seems to be closely related to the care with which a farmer tends his farm throughout the year. As there is no stable buyer policy farmers become discouraged in years when they have good crops and have difficulty selling it. Then the next year they do not take proper care of their farm.
Export is through traditionally established traders heavily influenced by the buying policies of the oversea users. Seaweed farming is made attractive to farmers by raising prices and lowering quality standards, but by the time a farmer gets into production the incentives are reduced again. This is an almost annual cycle of events, whether one is referring to the harvesting of wild crops or the farming of seaweed on a somewhat formal basis.
Currently Eucheuma of the “cottonii” type and Gracilaria are exported at about US$350 per ton. Eucheuma of the “spinosum” type is exported at, say, US$700 per ton. However, these are not real figures, as the amount of water included and the nature of the dry matter itself must be understood or a false impression of the value of the export material will be obtained. The amount of water permitted in the export crop should be stated, otherwise the buyer or seller, may not be receiving what he thinks he is receiving. A fresh kilogram of a seaweed, such as Eucheuma or Gracilaria, can be dried to between 1 and 200 grams and as such be exportable. Yet it may still be 30 percent water. If dried further it will be stiff, and at 10 percent or less water often cannot be compressed in bails or bags sufficiently to reach the most economical volume per ton density which relationship affects the shipping cost. Going the other way, even though an order may specify 30 percent or less water, it is often received containing 45, i.e. such a ton of seaweed has only 550 kg of dry matter in it.
The nature of the dry matter included in seaweed shipments may vary conspiciously. The desired seaweed may be 100 percent of the seaweed in a lot sold or less. It is lower especially in wild crop seaweed, where it may be less than 50 percent. Ten percent rocks, sand, leaf trash and “barnyard” litter is common. The higher purity of farmed “weed” makes it about twice as valuable per ton even though the gel strength may be 10 percent less than for wild crop material harvested at the same time. It is to be noted, too, that the desired gel quality may vary as much as 50 percent seasonally. Often buyers ask that the seaweed be bleached. This means soaking the seaweed in fresh or salt water briefly and redrying it. This will result in the seller losing 30 to 50 percent of his saleable material, a loss for which he should be compensated. Finally, 16 percent of the bone dry weight in otherwise untreated Eucheuma can be superficial salt which can be lost by the most brief rinsing of the dry seaweed in either salt or fresh water. As much as two-thirds of this salt can also be knocked off by hand labour or by running the seaweed through a hammer mill.
From the above, it is clear that there is more to judging the value of a seaweed shipment than just weight. Recently an American company received a shipment that yielded only 21 percent of the gel anticipated. The purchase was at a rather long (relatively) standing price, and consequently the shipment cost the buyer five times more per ton of gel than usual. Often when a buyer urgently needs seaweed he will drop, or ignore, his former specifications for quality requirements rather than be a price leader and raise the per ton price. In cases where the buyer quality standards may be raised but usually the price is lowered at the same time quality demands are raised, or buying is abruptly stopped.
Lack of trained personnel to carry on the development activities necessary to realize the Region's seaweed potential is a serious barrier. If a company wants to use a seaweed not now in use, there is almost no one to whom the company can turn to develop its production, or for that matter, a way they can be sure they will get the seaweed desired. There are possibly two phycologists resident in the Region capable of identifying a hitherto unknown seaweed and many of the Region's seaweeds are as yet scientifically unknown or badly confused taxonomically. Some order is being brought to the chaos surrounding knowledge of the regional species of Eucheuma. Gracilaria, the second most important seaweed which has a potential at least equal to that of Eucheuma is still in a very badly confused stage. Sargassum, and its relatives with significant commercial potential, is felt by most scholars to be the most taxonomically disordered group. However, once past the taxonomic stage, there is no one in the Region working actively toward commercial production of those seaweeds not already being produced commercially. Indeed, there are people repeating work that has been done elsewhere, but they are not moving the product toward its marketing. Thus, whether government- or industry-supported, technical people are lacking for realization of the apparently very large seaweed potential of the Region.
To develop the seaweed potential of the Region, use must be made of the coastal intertidal swamps, the mud flats of rapidly extending coasts, the embayments as well as the ponds and reef flats which are not now productive. The low wooded isles, often considered as atolls in the Region, are often but combinations of some of these site types. In some cases, e.g. in the South China Sea, there are reef flats with no land above high tide level, yet these may well be suitable for production of commercial seaweeds.
The opportunities are not those of the conventional fisheries development programmes or the capital intensive fisheries or aquaculture projects. Seaweeds are botanical organisms. Most are essentially of no value to the people but as a source of cash. Thus, much of what will be called opportunities are neither in the conventional realm of fisheries or aquaculture. However, many of them have been traditional sources of income to the Region's coastal peoples who may not be covered by current programmes of socio-economic development.
Since 1957 many opportunities have been seized by the author to study the marine shores of the South China Sea area. During this twenty-year period, reef areas in particular have been sought out and observed from the air or inspected by swimming or walking over them. While most of these studies were not done under FAO sponsorship, e.g. the initiation and development of the farming of “cottonii” type of Eucheuma in the Philippines during 1964–77, the principal reef areas, with the exception of Indonesia's, have largely been covered. In recent years, the Sea Grant Office of the United States has been supporting work by the author and associates which has permitted production of manuscripts, some of which are excerpted or abstracted to make part of the present report. The Programme, in cooperation with the office of the Director-General of Fisheries of Malaysia, supported aerial and on-site studies during 1975 and 1976 covering the non-mangrove marine shores of West Malaysia. Private industry and the Sabah Fisheries Department made it possible, during 1971–74, to study the reef areas of East Malaysia, Brunei and some of those in the South China Sea. Philippines and United States governmental agencies and especially Marine Colloids, Inc., of Rockland, Maine, made it possible to visit or make aerial studies, during 1975–76, of the major Philippine reef and shore areas. Many of the Hong Kong (census strictus) and Singapore areas have been visited. Vietnamese, Indonesian and other shores have been visited in the South China Sea area, but little other than Nha Trang area, southern Bali and southwestern Sulawesi has been studied in detail.
The literature on the seaweeds and other algae of the area, while scattered widely among the world's publications and often of very poor academic quality, can be divided into the academic and the applied. The academic literature for the Region is well cited in the bibliography of Velasquez, et al (1975) even though this bibliography is for a checklist of the Philippine marine algae and there are a number of more recent items. There is no library in the Western Pacific that has more than a scattering of these publications.
There is a paucity of literature on the applied aspects of seaweed and their production. Yet even in this small amount of literature there is a great deal of confusion and compounding of errors. Many of the titles referred to in various papers, especially in reference to the farming of Eucheuma, are really taken from manuscript drafts or duplicated training materials that were never intended to be published themselves, or they rephrase the very few basic publications. Even the most reliable are often constructed on data bases that are too small. Perhaps, the best single source is Naylor's (1975) “Production, trade and utilization of seaweeds and seaweed products” which though brief can be used with fair confidence as a data and bibliography source book. However, the following parts of this report and its appendices contain much otherwise unpublished information and more specific references to the pertinent literature.