Several seaweed species found in Fiji have economic potential based upon reports for the same genera in overseas countries. Some of these species are already used as food in Fiji and are a commodity traded in municipal markets. The most common economic seaweeds found in Suva Harbour and Tailevu during this survey were Gracilaria maramae, Gracilaria sp., Hypnea pannosa and Acanthophora spicifera. Other common seaweeds found in the localities visited included Laurencia spp., Gelidiella sp., Enteromorpha spp., Caulerpa racemosa and Sargassum sp.
Gracilaria maramae, Gracilaria sp., Hypnea pannosa and Acanthophora spicifera were generally found in the high subtidal or lower intertidal zones of relatively sheltered rockflats or mudflats and sandbanks. The latter two species tended to be restricted to areas where persistent low water salinity was likely to be rare. No seaweeds were found in very muddy habitats such as around mangroves near rivermouths, or where water circulation was very poor. Caulerpa racemosa was a dominant feature of clean sandy bottom in the subtidal zone away from freshwater influence, such as at Kaba Peninsula.
While widely distributed, these species (apart from Caulerpa) were not found growing in dense stands, and this is typical of many tropical islands. The survey was carried out in the off-season for seaweeds in Fiji, and in many places it was difficult to gather enough material for a phycocolloid sample. Even in the on-season (May-June to October-November), it is not likely that natural beds could provide a sustainable industrial-scale supply of seaweed at reasonable cost. Any new commercial utilisation of these species will depend upon the success (both technical and socio-economic) of aquaculture methods. Caulerpa, on the other hand, is fairly abundant in some areas and appears to be an under-utilised resource. Investigations into its export potential as a fresh sea vegetable may be warranted.
During the collection of seaweeds for this survey, gametophyte lifecycle stages for a not-previously identified species of Gracilaria were found for the first time. This discovery has enabled the species to be identified as Gracilaria edulis (Gmelin) Silva (Yamamoto, pers. comm.).
Samples of dried Gracilaria seaweed were submitted for analysis of phycocolloid quality, to determine if there is a chance of Fiji seaweeds finding a niche in world phycocolloid markets. In addition to seeking an opinion from Kadoya and Co. Ltd (a commercial seaweed importer in Japan), an independent view of phycocolloid quality was obtained from Industrial Research Ltd (IRL), a chemical laboratory in New Zealand.
The phycocolloids present in Gracilaria maramae South, G. edulis (Gmelin) Silva, and G. arcuata Zanardini v. snackeyi Weber van Bosse, were tested by IRL and the results have been published in Falshaw et al. (1999). Their conclusion was that each of these seaweeds holds some promise as a candidate for commercial agar production, and hence for aquaculture. The alkali-modified agars had reasonable gel strengths (>300 g cm-2 for 1% gels), good clarity and low colour and were obtained in acceptable yields. The G. arcuata v. snackeyi agar had a higher melting point (ca. 100° C) than conventional agars, which is a useful property for the food industry and is only the second time that a high melting point agar has ever been found in the Gracilaria genus.
The same samples analysed by IRL were also submitted to Kadoya & Co Ltd, who responded that the phycocolloid content was good but the gel strength was lower than their other existing sources (such as South America). They would consider buying Fiji Gracilaria only to blend into other supplies, and only if South American sources became scarce. Kadoya & Co. did not notice that one species had a high melting point agar, neither did they make any comment about it when we pointed it out to them after obtaining the results of our independent tests by Falshaw et al. We can perhaps assume from this that their seaweed market does not require this feature.
No carrageenophytes were tested as part of this study, because the species found (Hypnea pannosa, Acanthophora spicifera, Laurencia spp., Gelidiella sp.,) were all of low commercial interest internationally as carrageenan sources, except for one (Kappaphycus alvarezii, formerly known as Eucheuma cottoni) which is of high interest but has already been thoroughly studied in terms of carrageenan content and quality.
The techniques to cultivate Gracilaria species are similar to those for Kappaphycus and are fairly straight-forward. However a market already exists for Kappaphycus, but does not yet exist for these other species. Cultivation of Gracilaria in Fiji for export cannot be justified until a buyer has been found and a price has been established.
Utilization of Fiji seaweeds for phycocolloid uses must therefore be regarded as still being at the preliminary “bioprospecting” stage. Such bio-prospecting is worth doing, so that countries can identify their biodiversity resources (this is a requirement for countries that are party to the Convention on Biological Diversity). However it could be quite some time before there is any payoff in terms of the commercial utilization of these seaweeds as sources of phycocolloid.
Small-scale aquaculture of Gracilaria (lumi wawa) or Hypnea (lumi cevata) may be feasible for one of the following purposes; supply domestic or export food market for “lumi”, provide a food source for any aquacultured molluscs like greensnail or abalone, or provide a wastewater treatment for nutrient-rich effluent from prawn farms or sugar mills.
From 1986 to 1993 Fiji was an exporter of farmed Kappaphycus as a source of carrageenan. At the time that this study was carried out, there was no longer any Kappaphycus cultivation going on in Fiji, yet the outlook for Kappaphycus farming appeared to be still quite good. Recently, farming of this species has been re-started in Fiji and is now in an expansion phase of commercial development. This provides a good opportunity to try out farming of other seaweed species at low cost using established Kappaphycus farm facilities.
The focus of this study has been on phycocolloid-bearing seaweeds. It is also worth examining any Fiji species that might be acceptable substitutes for seaweeds eaten in Japan or other places. The top candidate for such an investigation would be Meristotheca procumbens from Rotuma because of strong market demand in Japan, but Caulerpa racemosa, some Gracilaria species, and Enteromorpha intestinalis could also be considered as fresh “sea-vegetables” for human consumption. Another key question is whether or not Cladosiphon sp. (“mozuku” in Japanese), now the basis of an export industry in Tonga, is also present in Fiji.
The most marketable of the edible seaweeds in Fiji would be Meristotheca and Caulerpa since there is good demand and top prices paid for these seaweeds in Japan. Unfortunately a joint FAO/USP trial of Meristotheca aquaculture on Rotuma showed that it is difficult to cultivate (Tanaka, in prep.), while Caulerpa is highly perishable and difficult to transport to market (Chamberlain, 1998). Cultivation of these species for export cannot be justified until these technical problems have been overcome.
The species of seaweed so far evaluated for commercialisation in Fiji fall into two categories; those which can be cultivated but presently have no export markets, and those which have ready markets but cannot be easily cultivated/transported. At the moment, only Kappaphycus satisfies criteria for both technical feasibility and market demand.
There are other seaweed species in Fiji (for example, over a dozen species of Gracilaria alone) which may have commercial potential, but this cannot be known at present because these other species have not yet been studied.