Field Document No. 1
SURVEY OF COMMERCIAL SEAWEEDS IN SOUTH-EAST VITI LEVU (FIJI ISLANDS):
A Preliminary Study on Farming Potential of Seaweed Species Present in Fiji
Seaweed Extension Specialist
Lumiwawa (Gracilaria maramae) from Tailevu on sale in Suva Market, 28 January 1995
Several seaweed species found in Fiji have economic potential as sources of industrial phycocolloids, judging from reports for closely-related species in overseas countries. Some of these species are already used as food in Fiji and are a commodity traded in municipal markets. This survey was planned to determine, in preliminary fashion, the distribution, abundance and seasonality of economic seaweeds in South-East Viti Levu, and find out whether there would be any demand for them as sources of phycocolloids.
The most common economic seaweeds found in Suva Harbour and Tailevu during this survey were Gracilaria maramae, Gracilaria edulis, Hypnea pannosa and Caulerpa racemosa. Other common seaweeds found in the localities visited included Acanthophora spicifera, Laurencia spp., Gelidiella sp., Enteromorpha spp., and Sargassum sp. Occasionally plants of Solieria (an edible seaweed) and Kappaphycus alvarezii (an exotic species introduced from Phillipines that was farmed in Tailevu up until 1993) were also found, but were not common. Gelidium pusillum has been previously reported as present in Suva Harbour in small quantities. Hypnea nidulans is common on some back-reef areas. Near Serua Island four types of Gracilaria were found; G. maramae, G. edulis, G. arcuata var. snackeyi, and a possibly new, undescribed species.
Gracilaria maramae, Gracilaria edulis, 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 seaweeds in many tropical islands. This survey was carried out during the off-season for seaweeds in Fiji, but even in the on-season (May-June to October-November) it is not expected 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 quite abundant in some areas and appears to be an under-utilised resource. Investigations into its export potential as a fresh sea vegetable are 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 and other species are similar to those for Kappaphycus and are fairly straight-forward. However an export 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.
At the time 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 quite good. Recently, farming of this species has been re-started in Fiji and is now in the expansion phase of commercial development. This provides a good opportunity to try out farming of other seaweed species on established Kappaphycus farms, as a farm now does not have to be started from scratch for trial purposes. Some small-scale aquaculture of Gracilaria or Hypnea species may be possible to supply local food or wastewater treatment requirements.
In addition to phycocolloid-bearing seaweeds, it is also worth examining any Fiji species that might be acceptable substitutes for seaweeds eaten in Japan. 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. 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 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 (Gracilaria, Hypnea), and those which have ready markets but cannot be easily cultivated/transported (Meristotheca, Caulerpa). At the time of writing, only the introduced seaweed Kappaphycus satisfies criteria for both technical feasibility and export market demand.
SOUTH PACIFIC AQUACULTURE DEVELOPMENT PROJECT (PHASE II)
FOOD AND AGRICULTURE ORGANISATION OF THE UNITED NATIONS
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2. LITERATURE REVIEW
2.1 Previous work on seaweeds in Fiji
2.2 Overseas studies on Gracilaria spp.
2.3 Overseas studies on Hypnea spp.
2.4 Overseas studies on Acanthophora spp.
3. SURVEY OF SEAWEED DISTRIBUTION AND ABUNDANCE
3.1 Site surveys
3.2 Market survey
3.3 Comment on abundance
4. SPECIES IDENTIFICATION
4.1 Collection and preservation methods
4.2 Significant species found
4.3 Significant species not found
5. SEAWEED SAMPLES FOR PHYCOCOLLOID ANALYSIS
5.1 Sample preparation method
5.2 Important considerations in phycocolloid testing
5.3 Phycocolloid results for three Fiji Gracilaria species
Appendix 1: Market survey questionnaire
Fig. 1 Map of Suva Harbour, showing survey sites
Fig. 2 Map of Kubuna Waters, showing survey sites
Fig. 3 Map of Serua District, showing survey site
Fig. 4 Wet weight of seaweeds for sale on Saturdays at Suva market since January 1992
Fig. 5 Prices of seaweeds for sale on Saturdays at Suva market since January 1992
Plate 1 Seaweeds found at Nasese;
(a) Gracilaria maramae
(b) Gracilaria edulis
Plate 2 Seaweeds found at Nasese;
(a) Hypnea pannosa
(a) Acanthophora spicifera
Plate 3 Seaweeds found at Nasese;
(a) Laurencia sp.
(b) Gelidiella sp.
Plate 4 Seaweeds found at Nasese;
(a) Enteromorpha sp. (two species)
(b) Comparison of Gracilaria edulis and G. Maramae