This area-by-area review of the seaweed resources of the world is based principally on Michanek (1975); it briefly describes the present state and development potential of the resources in each of the major fishing areas as defined by FAO for statistical purposes.
Arctic Sea (Fishing Area 18)
Most of the Arctic Sea does not provide accommodation for seaweed resources in harvestable quantities; weather conditions, scarcity of labour and general inaccessibility are also unfavourable to harvesting.
Northwest Atlantic (21)
Harvesting of red seaweeds, mainly Chondrus spp., is already well established in the Atlantic provinces of Canada. The Nova Scotia/Gulf of St. Lawrence area is believed to be one of the richest in seaweeds in the world. The production of red algae might be capable of a two or threefold increase above present levels, the main underutilized species being Rhodymenia palmata, Furcellaria fastigiata and possibly Ptilota serrata off Newfoundland, Ahnfeltia, Gracilaria, Phyllophora and Porphyra spp. Few of the area's brown seaweed resources have so far been exploited and there appears to be potential for the commercial development of Ascophyllum nodosum, Laminaria and Alaria spp.
Northeast Atlantic (27)
The use of seaweed is long established in this area, notably in Norway, Scotland, Iceland, Ireland, France, Spain, Portugal and Denmark.
The seaweed resources of Iceland are believed to be among the largest underexploited algal resources in the world. Brown rock-weeds are particularly abundant on the island's southern coasts, broad belts of Ascophyllum dominating vast areas of the littoral slopes; considerable resources of agar-bearing species are also present. Very extensive stocks of brown algae, notably Ascophyllum, Laminaria and Fucus spp., are present off the Arctic sea coast of the U.S.S.R., and rich resources of the same species are already fairly extensively exploited by Norway. Harvestable quantities of Furcellaria fastigiata are to be found in many parts of the southern Baltic in addition to those already extensively exploited by Denmark.
Detailed surveys of the seaweed resources of Scotland have indicated a potential harvest, primarily of Laminaria, of the order of one million tons (wet weight) per annum, but in common with the abundant resources of both brown and red seaweeds identified off Ireland, their practical exploitation is limited in many cases by inaccessibility. French production of red and brown algae may be capable of expansion; the harvest of red and, particularly, brown seaweeds off the Iberian peninsula has also probably not reached its fullest potential.
In summary, whilst opportunities for the economic expansion of the area's resources of red seaweeds may be relatively limited, a very considerable underexploited potential appears to exist for greater use of the brown algae, particularly in Iceland.
Western Central Atlantic (31)
The coastal seaweed resources of this area are believed to be only moderate; however, for many parts of the area there is still little information. Recent surveys along the U.S. Gulf coast identified unexpectedly varied and abundant flora, especially in offshore waters; the Caribbean is also known to be rich in algae, although possibly the commercially attractive species do not occur in economically sufficient quantities. Additionally, the standing stock of the so-called Sargasso Sea is said to amount to some millions of tons of (brown) algae which, if harvestable, could yield a potential of perhaps a million tons or more per annum.
East Central Atlantic (34)
The use of seaweeds in this area is presently concentrated in the north where Morocco harvests resources of Gelidium which are probably capable of greater exploitation, particularly (if communications can be improved) those to the south, near Tarfaya. Further south, the tropical regions of the area are rather poor in algal vegetation. The main potential appears to rest with Hypnea resources off Dakar, which are now being harvested for export.
Mediterranean and Black Sea (37)
The seaweed resources of the Mediterranean are rather moderate. A number of species might be considered as commercially attractive, for example, Laminaria off the south coast of Spain, Rissoella verriculosa along the Mediterranean coast of France, Cladophora prolifera, Fucus and Cystoseira spp. off southern Italy, Sargassum, Cystoseira, Hypnea and Vidalia off Yugoslavia.
In the Black Sea the resources of Phyllophora represent possibly the single greatest accumulation of red algae in the world and the U.S.S.R. phycocolloid industry based upon this species is almost certain of further expansion. Plans have also been elaborated for a Bulgarian phycocolloid industry using this resource.
Southwest Atlantic (41)
Off the north of Brazil a large number of algae, especially red species such as Gracilaria and Hypnea are abundant and a large-scale programme for the exploitation of these resources has been launched. Red algae, notably Codium spp. are already extensively harvested in Argentina and to the south, the Macrocystis resources of Patagonia, Tierra del Fuego and the Falkland Islands may well represent one of the world's largest untapped resources of seaweeds.
Southeast Atlantic (47)
Off the coast of southwest Africa the resources of Gracilaria and Gelidium are already of commercial importance; other potential agarophytes are Hypnea spicifera, which is particularly abundant, Iridophycus and a variety of red algae. Ecklonia, Laminaria and other brown algae are also believed to be resources of potential commercial interest.
Western Indian Ocean (51)
The seaweed resources of this area are presently only very lightly exploited. Off Tanzania, where Eucheuma is already of commercial importance, attractive resources of Hypnea, Sargassum, Turbinaria and Ulva are known to be present but are not yet utilized. Resources of Hypnea and Sargassum have been identified off the Sultanate of Oman in sufficient quantities to form the possible base for commercial development; abundant strands of Hypnea are also found off parts of the Pakistan coastline. Considerable attention is being given to the possibility of expanding the presently small-scale seaweed industry in India, off certain parts of which resources of Sargassum, Gracilaria, Gelidium and Hypnea have been discovered. Opportunities are believed to exist for the greater exploitation of Sri Lanka's resources of Gracilaria and for the use of Sargassum and Turbinaria.
In the very south of the Western Indian Ocean, enormous resources of Macrocystis and Durvillea kelp species have been identified, together with Iridea in commercially attractive abundance, in the fjords and islands of Kerguelen; in the Baie du Morbihan alone, estimates of the total biomass of the Macrocystis undergrowth indicate a resource of seaweed which must be regarded as among the largest in the world. However, because of transport and other practical difficulties, the commercial exploitation of these resources seems unlikely in the foreseeable future.
Eastern Indian Ocean (57)
Seaweeds are fairly widely consumed for human food in this area but commercial harvesting has been undertaken only in Tasmania, Australia. Considerable quantities of Macrocystis are believed to be present off southern Australia but might be difficult to harvest mechanically.
Northwest Pacific (61)
About two thirds of the entire world production of seaweeds is presently harvested in this area, principally for human consumption, in Japan, China, the Korean peninsula and the Pacific coastal regions of the U.S.S.R. The rise in demand has been such that the naturally growing resources in this area are probably not capable of supporting any significant intensification of exploitation, with the possible exception of Laminaria resources northeast of Vladivostok, the Strait of Tartary, and localities on Kamchatka and the Sea of Okhotsk. Expanded production in this area will almost certainly arise from the further development of the already well established cultural practices.
Northeast Pacific (67)
The whole of the coastal areas of the Northeast Pacific is dominated by very considerable resources of kelp species, in particular Macrocystis and Nereocystis which so far have been virtually untouched. The estimates derived from resources surveys and inventories over the last sixty years for various parts of this area, from Alaska to British Columbia and Oregon, are to some extent conflicting but all point to the existence of brown seaweed resources of considerable potential, if often rather inaccessible. An indication of their amplitude can be gathered from a number of surveys which covered only readily accessible areas near Vancouver Island which suggested that at least one million tons annually of Macrocystis, Nereocystis, Laminaria, Alaria and other algin-bearing weeds were commercially available off British Columbia. Resources of Iridea and Gigartina, whilst quantitatively much smaller, are also believed to be of some importance.
West Central Pacific (71)
Human consumption of seaweeds is widespread throughout this area although production, quantitatively, is probably relatively small. With a few exceptions, the resources have not been extensively studied and there is little evidence upon which to base estimates of potential harvestable production.
In Indonesia, it may be possible to develop export markets in Hypnea similar to those already established with Eucheuma. Throughout the entire area, the future development of cultural practices could well be the main impetus behind the future growth in output of seaweeds.
East Central Pacific (77)
The giant kelp of California is perhaps the most comprehensively investigated seaweed resource in the world. Some estimates of potential production are as high as 35 million tons per annum (assuming two harvests annually); more conservative workers suggest harvestable quantities of between 1 and 3 million tons per annum. It at least seems reasonable to assume that the potential is very considerably higher than the harvests presently drawn (about 150 000 tons per annum).
Gelidium is also present in abundance off the Californian coast, but labour costs in the U.S.A. have discouraged any extensive harvesting of this species. The distribution of this resource continues south to the Mexican coast and its exploitation by Mexico has been steadily increasing. Mexico is also harvesting quantities of Macrocystis and, in both cases, together with known resources of as yet unused Eucheuma and Eisenia, there is almost certainly considerable scope for further expansion of output.
Southwest Pacific (81)
The seaweed resources of this area, which in effect consist of New Zealand and the southeastern coasts of Australia, appear to be rather small. The lengthy New South Wales coastline is believed to possess Gracilaria resources sufficient to support an output of 100 tons of agar annually. In New Zealand Pterocladia is already the basis of small industry extracting high quality agar and attention has more recently been given to the feasibilities of economically using resources of the bull-kelp, Durvillea.
Southeast Pacific (87)
The coastlines of Chile and Peru are fairly rich in algae. The exploitation of Gracilaria and other red seaweeds by Chile is now well established. In the southern third of Chile resources of kelp species, principally Macrocystis, are likely to be considerable, if patchy; the Straits of Magellan, for example, are assumed to hold very large seaweed resources. Poor communications, distances from markets and adverse weather conditions are severe problems but the possibilities of commercial utilization of these resources are being actively investigated as their exploitation would make a valuable contribution to the overall economic development of the region.
Peru also possesses undoubtedly abundant resources of various seaweeds, in particular Macrocystis, Gigartina and Ahnfeltia spp., but their commercial exploitation is still at a very early stage.
Antarctic Areas (48, 58, 88)
A number of investigations have established the presence of sometimes luxurious resources of algae in parts of this region. The harvesting of these resources can hardly, however, be regarded as a practical or economic proposition because of the problems of remoteness and adverse climatic conditions.
