The focus of this project is the winged pearl oyster, Pteria penguin, and project research will facilitate propagation of this species in support of the cultured pearl industry in Tonga. Much of this research relies on successful hatchery culture of Pteria penguin which has a restricted reproductive season in autumn. On this basis, initial project activities focused on preparation of the hatchery facility in Tonga for hatchery culture in May 2008. Spawning induction was readily achieved on multiple occasions and large numbers of eggs and larvae were obtained for hatchery culture. The success of hatchery culture efforts will not be known until mid 2008 when resulting juveniles will be used to establish nursery culture experiments.

A hatchery spawning in Australia in February 2008 failed to produce significant numbers of juvenile oysters but a nursery culture experiment was established in April 2008 using wild collected juveniles. The results of this experiment will be known in mid 2008. Research into factors influencing reproductive conditioning of Pteria penguin was begun in Australia in 2007. The results will hopefully allow oysters to be conditioned for hatchery culture outside their normal reproductive season which will allow hatchery culture to be extended throughout the year.

The focus of this project is the winged pearl oyster, Pteria penguin and project research will facilitate propagation of this species in support of the cultured pearl industry in Tonga. The first hatchery run in Tonga in May 2008 produced a large quantity of spat (~60,000). The spawning induction and larval culture methods used were based on those developed for other species of pearl oyster in a prior ACIAR project (FIS/97/31). However, relatively cold water temperature and problems with live micro-algae culture at the Fisheries facility in Tonga forced the following modifications to culture methods:
Used of a heat-exchange system to maintain good water temperature in larval culture tanks; and
Used of commercially available micro-algae concentrates as food for the larvae.
A major output was the successful use of commercially available micro-algae concentrates to feed pearl oyster larvae. Larvae were reared to settlement on these products demonstrating that live micro-algae culture is not necessary for larval culture of pearl oysters. This has major potential benefits for hatchery culture of pearl oysters (and other invertebrates) in the region, including reduced reliance on dedicated hatchery infrastructure, reduced hatchery costs and elimination of the need for specialised algae-culture skills.

Spat resulting from the May 2008 hatchery run were used in two 4-month experiments to determine survival and growth of Pteria penguin in different culture units at two locations in Tonga (Sopu and Vava'u). The first experiment (completed in February 2009) determined growth rates and survival of oysters held in different nursery culture unit at the two sites. The type of culture unit had a significant impact on growth rate and survival of oysters with oysters held in plastic mesh trays showing the greatest growth rates. The results showed that hatchery cultured Pteria penguin would reach pearl seeding size within 1 year of age. The second experiment used the same culture units to hold larger oysters at three sites and at two depths. It began in February 2009 and will finish in June 2009.

Approximately 30,000 of the hatchery cultured juvenile oysters produced by the Project were provided to two oyster farms in February 2009 to alleviate their oyster stock shortage. Tonga Fisheries staff will be involved with the regular maintenance of these oysters to generate additional growth rate data to compliment that from Project growth trial (i.e. additional sites). Pearl farmers and locals involved in making pearl handicrafts meet with Project staff (both JCU and Tonga Fisheries) on a regular basis for Project updates.

The focus of this project is the winged pearl oyster, Pteria penguin, and project research facilitates propagation of this species in support of the cultured pearl industry in Tonga. Annual hatchery production in Tonga in 2008, 2009 and 2010 has been successful in producing a large quantity of spat. The spawning induction and larval culture methods used were based on those developed for other species of pearl oyster in a prior ACIAR project (FIS/1997/31).

A major output of the hatchery activity was successful use of commercially available micro-algae concentrates to feed pearl oyster larvae. Larvae were reared to settlement on these products demonstrating that live micro-algae culture is not necessary for larval culture of pearl oysters. This has major potential benefits for hatchery culture of pearl oysters (and other invertebrates) in the region, including reduced reliance on dedicated hatchery infrastructure, reduced hatchery costs and elimination of the need for specialised algae-culture skills. Large-scale hatchery production of Pteria penguin has been supported by laboratory-scale experiments to determine the optimal culture requirements of Pteria penguin larvae. The results will be used to fine-tune hatchery techniques and develop a standard hatchery protocol for this species.

Spat resulting from the 2008 and 2009 hatchery activities were used in experiments to determine survival and growth of Pteria penguin in different culture units, and the influence of depth and site. The type of culture unit had a significant effects on growth rate and survival of oysters and different culture units were found to be optimal for different sizes of oysters. The results will allow a standard culture protocol to be developed for pearl farmers in Tonga. Results of the growth trials indicate that hatchery produced Pteria penguin require more than 2 years to reach a size suitable for half-pearl production (ca. 170 mm).

Approximately 50,000 of the hatchery cultured juvenile oysters produced by the Project have so far been provided to the oyster industry to alleviate oyster stock shortage. Tonga Fisheries staff are involved with the regular maintenance of these oysters to generate additional growth rate data to compliment that from Project growth trials (i.e. additional sites) and to facilitate training and capacity building. Pearl farmers and locals involved in making pearl handicrafts meet with Project staff (both JCU and Tonga Fisheries) on a regular basis.

Regular supply of large numbers of oyster juveniles to pearl farmers in Tonga has stimulated renewed confidence in the industry. This has resulted in:

disaffected pearl farmers returning to the industry;
new farmers entering the industry;
enquiries about establishing pearl farming in new areas (e.g. Tongatapu); and
an expanding and more proactive Pearl Growers Association.

The Project was recently extended until June 2011 when a larger follow-up project is scheduled to begin.