Apart from giant clam culture, since the mid-1950s, more than five other species, including, Mozambique tilapia (Oreochromis mossambicus), edible oyster and mussels (European flat oyster - Ostrea edulis, Sydney cupped oyster - Saccostrea commercialis, New Zealand rock oyster - S. glomerata, Pacific cupped oyster - Crassostrea gigas and Lugubrious cupped oyster - C. belcheri), mullets (Liza macrolepis and Valamugil seheli) and seaweed (Eucheuma spinosum & Kappaphysus) have been trialled as potential aquaculture products since the mid-1950s, but have failed to become feasible ventures to operate at commercial levels. Only the winged pearl oyster (Pteria penguin) has managed to develop successfully to a somewhat small commercial scale with sales mainly in street markets to visiting tourists.
Currently, there are around six applicants seeking licences to farm sea cucumbers, however to date these licences have not been issued. Issues have arisen with supply of juveniles as the proposed sea cucumber farms will be heavily reliant on imported hatchlings, from an international commercial hatchery, and includes wild selected sea cucumbers species to improve the fertilization rate.
Overall, despite great advances in the last decade, aquaculture in Tonga, is still largely in experimental stages for most of potential aquaculture commodities. Further development of this industry is currently an ongoing process receiving technical support from the Secretariat of Pacific Communities (SPC), the Australian Centre for International Agricultural Research (ACIAR), the Japanese International for Co-operation Agency (JICA) and the Food and Agriculture Organization (FAO).
The first aquaculture experiments conducted in Tonga were fish pond culture systems, which were initiated in the mid-1950s, but later trialled for fish culture as part of an integrated farming system project with a piggery. In the early 1970s broodstock of the Penguin wing oyster (Pteria penguin) were imported from Japan for initial culture trials by a private company. However, in 1989 FAO’s South Pacific Aquaculture Development Project (SPAFP), as part of the FAO, persisted with the trial culturing of pearl oysters, supported by the Tongan Fisheries Division. This provided great assistance in carrying out stock assessment, spat collection surveys, and grafting techniques; these methods are still currently exercised by the pearl farmer located at the Vava’u Island group. Edible oyster and mussels were also introduced for the potential of further aquaculture projects in 1973–1974, but culture trials ended with inconclusive results.
In 1978, the Fisheries Mariculture Centre (FMC) was established with the assistance of theJapanese Government assistance, but only for the culture of mollies (Poecilia vittata) in order to meet the demand for tuna bait in commercial fishing; this project was terminated in the same year. The seawater pump system installed as a result of this project was demolished by a tropical cyclone in 1982 and consequently renovated in 1989 through the assistance of an ACIAR project to meet the standards of a giant clam culture system. Further upgrades by JICA in the late 1990s improved this facility to a seawater flow through system, which now is the Fisheries Mariculture Centre located in Sopu. As a result, commercial top (Trochus niloticus) and green turban (Turbo marmoratus) were included as culture species together with the giant clams species, but both were aimed for resources enhancement rather than commercial production. Hard corals and live rock farming are the most recent introduction to the cultured species at the Mariculture Centre. The project commenced in 2009, but thus far, there has been limited success as the markets for coral is highly competitive, and in addition, the recent global economic crisis has seen drops in demand for aquarium organisms.
The culture techniques for giant clam species (Tridacna derasa, T.maxima, T.squamosa, T.gigas, T.crocea) were successfully established by the Fisheries Mariculture Centre in 1989 with the technical assistance of ACIAR and supported by the Japanese Government under JICA, after the ACIAR programme terminated in the early 1990s. JICA also assisted with aquaculture activities until early 2000s when trochus commercial top (Trochus niloticus) and green turban (Turbo marmoratus) were included as an additional cultured species, after being introduced from Japan and Vanuatu for stock enhancement purposes. In fact, giant clam is the only major aquaculture product produced in Tonga since the late 1990s after being established internationally in the ornamental market by the aquarium traders, issued with licences by the Tongan Fisheries Division.
Penguin wing oyster
Penguin wing oyster (Pteria penguin) were introduced from Japan in the early 1990s for pearl oyster trials but the first results were inconclusive. In 1989, SPADP of FAO, continued the farming trial with the end results indicating low spat production from hatchery runs. However, by early 2008, hatchery runs, under ACIARs mini project programme of the Regional Pacific which includes Tonga, yielded around 300 000 spats successfully being produced. The oysters were transferred to the FMC oyster longline at Sopu for further grow-out and later distributed to the pearl farmers located in Vava’u. Approximately 4 000 spat have been produced, grown out and distributed to the pearl farmers from the mariculture hatchery, with the assistance of ACIAR/SPC (2008–2010). The current target pearl production is the half pearl or ‘MABE’ pearl, which is currently focused on supplying the domestic market for tourism purposes.
Hard corals & live rocks
The launch of hard corals and live rocks farming in 2009 was part of the technical assistance provided by SPC/ACIAR to the Pacific Region, which aims to produce cultured live rocks and corals for supply to the aquarium ornamental trade. In August 2008, the Tongan Government put a national ban on the harvest and export of both live rocks and corals. This resulted in one company closing down, and as a consequence, other companies having to switch to target and catch other species (fish/invertebrates) in order to stay in business. As result, SPC provided technical assistance with ACIAR funding to trial aquaculture live rocks and corals at the mariculture facility in Sopu. Market trials are still in progress, but no export has been made since launching this project.
Tilapia farming initiated in the mid-1950s and followed up with other various culture trials such as introducing the species into freshwater and brackish lakes throughout the Tonga Island chain, but no major large-scale production ever eventuated, as local people lost interest in the species. Currently, locals treat tilapia as a pest, as a result of similar cases, whereby, tilapia were introduced into a brackish lake in which milkfish Chanos chanos were prominent, but soon disappeared after a few years, where tilapia is thought to be the most likely culprit by competing with the milkfish and eating their larvae. However, the introduction of tilapia to Tonga had a secondary aim in trying to reduce the mosquito population, but this attempt was also not successful. As a result, no more tilapia farming exists except for fishing at various freshwater bodies for home consumption only.
Mullet is a high priority aquaculture product, as it is the most commonly target fish species by gillnet fisherman. As a result, mullet fry of flathead grey mullet Mugil cephalus were imported from Hawaii in 1990 and introduced to Lake Ano, which is located in the Vava’u group. The sea mullet grew to adult stages but no natural spawning occured. In 1992-1993, mullet fry were collected from the coastal area of Tongatapu and stocked into pens culture for grow-out, but this project was terminated in 1995 due to the production costs of the mullet being too high when compared with sale prices at the local fish market (Fa’anunu et al., 1994).
In 1982, an experimental trial with seaweed farming for Eucheuma spinosum and Kappaphycus initiated after importation of seed stock from Fiji, by a private company, and were planted at a farm site in the Vava’u group. The Fisheries Division also set-up an experimental farm at Fanga’uta lagoon located in Tongatapu with the seeds transferred from Vava’u in 1986. By 1987, 14 farmers were operating, with each farmer possessing around 50 lines. After harvesting in 1987, no more farming activities continued due to market issues (Annual report, Fisheries Division, 1989).
The Fisheries Mariculture Centre at Sopu, Fisheries Division, was first established in 1978 and upgrade during late 1990s with the technical assistance of the Japanese Government (JICA). Currently, giant clams, trochus, greensnail, soft and hard corals, live rocks, and sea cucumbers are the aquaculture species in place at the facility, but the focus is on experimental activities with the exception of giant clam juveniles, which are sold to local traders for export.
The graph below shows total aquaculture production in Tonga according to FAO statistics:
Aquarium market – International
The Sopu Fisheries Mariculture Centre is the main producer of giant clams production for exportation by the Aquarium operators, in fact, the demands from the international market cannot be met by the current production of giant clams.
‘MABE’ – Local market
For half pearls ‘MABE’, the primary markets for this product consists of the simple jewelry and souvenirs for tourists travelling to and through the Vava’u Island group, which is the major tourist destination in Tonga. No data has been recorded for the number of items sold at the local markets annually, but it is estimated that 500–800 pieces half pearls were sold during 2009 and less than 500 pieces sold in 2010.
There is little doubt that the contribution of ‘MABE’ production to the local economy of the people in Vava’u clearly provides small-scale employment for local people, as most of the pearl farmers are owned and operated by families (small-scale aquaculture), rather than large scale farms. The staff currently employed at the aquaculture section of the Fisheries Division provide the only form of employment opportunity in Tonga, unless the promotion and development of aquaculture activities to a commercialized level occurs.
A few areas that have been highlighted for development for the half pearls ‘MABE’ industry include a need to establish the local farms internationally in a way to improve or increase the income for the pearl farmers. Subsequently, there is still room for improvement to be made by capacity building for farmers with further training in areas such as grafting techniques, seeding and farm management.
Annual report 2008. Ministry of Agriculture & Foods, Forests and Fisheries – Fisheries Division Unpiblished data), Tonga.
Aquaculture Research and Development Section Database, 2011. Ministry of Agriculture Foods, Forests & Fisheries Division. Tonga.
Fa’anunu, ‘U., Fale, P., Paongo, ‘O., Taholo, L., Kawaguchi, M., 1994. Mullet fry collection along cosatl areas of Tongatapu. Fisheries Research Bulletin of Tonga V 1: 1-6.
Ngaluafe, P.,2009. Tonga Aquaculture Profile. Aquauclture Research and Development Section, MAFFF, Tonga (unpublished Data).