Pacific Island pearl oyster resource development

• Ministry of Environment and Natural Resources Development, Kiribati

Recent developments in Polynesia have shown the potential for major export earnings from cultured black pearl and mother-of-pearl shell industries. This has aroused considerable interest because small remote Pacific island nations (e.g. Kiribati, Solomon Islands and Fiji) have limited opportunities for export trade.

The blacklip oyster pearl, Pinctata margaritifera, has a wide geographical distribution and flourishes in atoll lagoons. However, up to the mid-1900s, natural stocks of pearl oysters were seriously depleted and many Pacific island countries such as Kiribati and the Solomon Islands now cannot support an industry.

In French Polynesia, black pearls have become a major export earner in recent years with about 600 kg exported in 1990 worth US$36.5 million. The Cook Islands are also benefiting from black pearls and Kiribati, the Solomon Islands and Fiji are all keen to rehabilitate their wild pearl oysters so they are able to sustain economically viable pearl culture operations.

The objectives of this project are:

to assess the natural pearl oyster stocks of Kiribati and Fiji and the rates of spatfall (newly settled juveniles) of blacklip pearl oysters in the atoll lagoons of Kiribati;

to develop appropriate technology for hatchery and nursery culture of juveniles; and

to improve the yields of gem-quality and average pearl quality pearls through better bead insertion procedures and oyster management practices.

The research in Kiribati will focus on lagoon channels selected from grided charts.

For spatfall studies, scientists will use commercial spat-collectors (bags) deployed on horizontal longlines. Date, location, numbers of spat, and measurements of juvenile growth and survival in the bags will be monitored.

In the first year, the study will be conducted by researchers from James Cook University, and in the Solomon Islands at the International Centre for Aquatic Resource Management Coastal Aquaculture Centre (ICLARMCAC). P. margaritifera broodstock will be collected and induced to spawn.

Scientists will keep the eggs in static seawater with antibiotics until the early viliger stage is reached and then transfer healthy larvae to different designed nurseries in the ocean and onshore where different diets will be tested. If successful Kiribati and the other countries will follow in the second year of the project. Training will be given to fisheries personnel from the Pacific countries involved in the culture techniques.

Researchers at the Queensland Department of Primary Industries (QDPI) will carry out surgery studies to test the use of antiseptics and anaesthetics and to determine the importance of aseptic techniques, wound closure and bead/mantle graft insertion for the implantation of pearl beads in the oysters.