The latest information on pearl farming in Tahiti

Although recent in Zanzibar, pearl farming illustrates how scientific research can support projects that are both ecological and economically viable.

In 2006, Maria Haws (University of Hawaii) and Narriman Jiddawi (Institute of Marine Science – IMS) introduced women’s groups from the Fumba Peninsula to pearl farming techniques.

The Sustainable Coastal Communities and Ecosystems Project, funded by USAID, enabled the Western Indian Ocean Marine Science Association (WIOMSA), IMS, and their partners to work with women’s groups in four villages near Menai Bay to promote half-pearl (mabé) culture.

Before this project, these women cultivated seaweed, worked the land, or collected shellfish for an average monthly income of only USD 40–50, requiring 5 to 7 days of work per week.

Promising Initial Results

In January 2007, an experimental batch of 94 Pteria penguin oysters was grafted to produce half-pearls. Each oyster received two to three hemispherical nuclei before being placed in pouches suspended from a raft at a depth of four meters, near Bweleo.

After one year, the operation yielded 28 high-quality half-pearls. Several were sold at auction during a gala dinner organized in February at the Palace Museum. This event, co-organized by WIOMSA and IMS and hosted by N. Jiddawi and A. Mmochi (IMS), was inaugurated by the Minister of Women’s Affairs and Youth, Asha Abdulla, and raised USD 3,600.

Toward Tourist Commercialization

Some of the remaining pearls were set in silver or gold and will be offered for sale to the 100,000 tourists visiting Zanzibar each year, paving the way for a new and sustainable source of income for local communities.

Akoya pearl oysters (Pinctada fucata), into which a nucleus is implanted to produce spherical pearls, often show a low survival rate and a high rate of nucleus rejection. The hypothesis tested in this study is that using relaxing agents before implantation could reduce the oysters’ metabolism and improve graft success.

Tested Protocols

Researchers tested three relaxing agents: propylene phenoxetol, 30% magnesium sulfate, and 10% MS222. The optimal concentrations and durations were found to be 2.5 mL L⁻¹ for 6 minutes, 15 mL L⁻¹ for 11 minutes, and 2 mL L⁻¹ for 7 minutes, respectively.

At the beginning of anesthesia, oysters exhibited a high oxygen consumption, which gradually decreased and stabilized, unlike untreated oysters, whose metabolism remained more active.

Results on Survival and Rejection

Oysters transferred to the sea immediately after nucleation showed a higher survival rate eight months after the operation compared to those kept in concrete tanks for four weeks before being moved to the sea. The rate of graft rejection was also lower in the first group.

Impact on Pearl Quality

Despite these positive results on survival, pearl formation was better in oysters that had not received a relaxing treatment. The average pearl diameter in this group was 6.62 mm, compared to 6.52 mm (30% magnesium sulfate), 6.48 mm (propylene phenoxetol), and 6.46 mm (10% MS222) in treated oysters.

These results indicate that while the use of relaxing agents improves survival and reduces nucleus rejection, it may slightly affect the final size of the pearls produced.

In this study, the authors analyze the economic viability of a small aquaculture business specializing in the farming of black-lipped pearl oysters. The goal is to propose a model that could serve as a complementary economic activity for communities in the outer islands of the Central Pacific.

A Quantified Scenario

The researchers developed detailed financial projections for a pearl farm cultivating 25,000 grafted oysters using the Tahitian method of tying oysters to longlines. The model includes estimates of initial investment, annual operating costs, cash flow, and the overall business budget.

The results indicate that an initial investment of USD 202,076 is required to start the activity.

Operating Costs and Expense Categories

At full capacity, annual operating costs reach USD 293,726. The main expense categories are:

• Grafting: 46% of the annual budget
• Labor (including the owner’s opportunity cost): 24%
• Depreciation: 9%

Long-Term Profitability

According to the proposed model, profitability is achieved after 20 years. Over this period, with an 8% discount rate, the net present value of operating net returns is estimated at USD 102,945.

A sensitivity analysis was conducted, taking into account market price variability, oyster survival rates, grafting costs, and other production factors. The results make it possible to assess the economic robustness of the project under different scenarios.

As part of feasibility studies on the farming of Pinctada imbricata along the central coast of New South Wales, pearl oysters were introduced at a series of sites ranging from the state of Victoria to New South Wales.

This three-year series of trials aimed to measure the influence of site on growth, survival, and nacre quality. Groups of sibling oysters were placed at sites stretching from Port Phillip Bay, in the far south of Victoria, to the central coast of New South Wales. The results revealed significant differences depending on location.

Latitude and Growth: An Observed Correlation

Observations show that oyster growth generally decreases as latitude increases. This trend may be linked to lower average water temperatures. However, significant growth variations were also recorded at sites where temperature did not appear to be a determining factor.

Shell analysis revealed a close correlation between nacre thickness and oyster growth.

Color and Luster: Variability Across Sites

Nacre quality — in terms of color and luster — was assessed by a panel of independent experts, who rated it according to commercial value. The results show that color and luster vary significantly from one site to another, without showing a correlation with growth.

Moreover, the quality of color and luster are not necessarily related to each other at a given site.

Changes Over Time

At sites monitored over multiple consecutive years, the relative quality of nacre color and luster changed over time, confirming the importance of long-term monitoring to better understand the effect of the environment on pearl production.

The value of a pearl increases exponentially with its quality. Among the evaluation criteria, shape plays a decisive role: perfectly round pearls are by far the most sought after and command the highest prices.

Thus, the primary objective of any pearl farmer is to increase the percentage of round pearls in their production. To determine whether genetic lineage influences pearl quality, two groups of Pinctada maxima were monitored over four years, from hatchery to harvest.

Two Groups, Two Origins

Group A came from the spawning of gold-lipped oysters selected in the Aru Islands, southeast of Indonesia.

Group B consisted of oysters bred from individuals originating in the Raja Ampat Islands, northeast of Indonesia, all of which had gold- or yellow-lipped nacre.

Both groups were raised under identical conditions at a commercial pearl farm located in Alyui Bay, West Papua.

Results: Lineage Makes a Difference

At harvest, researchers observed significant quality differences, particularly regarding shape.

Oysters from Group A produced a higher percentage of round pearls than those from Group B, demonstrating that lineage plays an important role in the final quality of pearls.

Toward More Efficient Selective Breeding

These results suggest that selective breeding could become a key tool for improving the quality and, consequently, the value of the pearls produced.

Coral Sea Pearls has established a grow-out farm for Pinctada imbricata oysters in Hervey Bay to produce high-quality Akoya pearls. The oysters used are sourced from local populations of this species, which is native to Queensland.

Highly prized for their smaller diameter (6–10 mm) and perfect shape, Akoya pearls stand apart from South Sea white pearls. Their exceptional quality is attributed to the purity of the waters of the Great Sandy Straits, the unique combination of seawater and estuarine water, and the ideal temperatures that promote the production of pearls with remarkable luster.

History and Development of the Industry

Pearl oysters have been present in Australian coastal waters for over a century, from the state of Victoria to Shark Bay in Western Australia. In the early 1990s, before pearl farming was developed, the Australian Museum had already identified several Akoya oyster populations in Hervey Bay.

An initial experimental lease was set up in 1999 at Port Stephens (New South Wales). The results of this trial showed that the site was then the most suitable for producing high-quality Akoya pearls in Eastern Australia. Today, Queensland is proving to offer even greater potential.

Coral Sea Pearls is building on the expertise gained at Port Stephens to develop production in Queensland. The purity of the waters and the tidal dynamics create ideal conditions for growing large pearls with brilliant luster.

The Production Site at Hervey Bay

Aquaculture has long been practiced in Hervey Bay, where experienced growers of native oysters contribute their know-how. Pearl production is expected to complement the local economy and integrate harmoniously with the bay’s tourism industry.

Akoya oysters are raised on four marine leases, where they grow in net panels. The onshore facility, located at the Urangan marina, serves as the operational base for the pearl farming activities.

Environmental and Marine Species Protection

Coral Sea Pearls places special emphasis on protecting Hervey Bay’s iconic wildlife: whales, dolphins, turtles, and dugongs, which are indicators of a healthy local ecosystem.

The leases have been designed to minimize risks to these animals. The lines are tensioned to prevent entanglement, and the company strictly adheres to current ecological best practice guidelines.

A continuous wildlife monitoring program is implemented in collaboration with the Department of Environment and Heritage. Coral Sea Pearls is proud to be the only aquaculture company in Queensland with such official authorizations.

The first farms established in the region relied on collecting adult and juvenile oysters from the reefs. This approach quickly failed due to the lack of adequate natural resources.

The First Hatcheries and Their Challenges

A private hatchery operated in Majuro (Marshall Islands) from 1998 to 2001, temporarily supplying two commercial pearl farms. However, technical problems — both in the hatchery and in the nursery — soon compromised its success.

Following this setback, the governments of the Federated States of Micronesia and the Marshall Islands established three hatcheries of various sizes and objectives, some with a research focus. These hatcheries are located at the College of Micronesia – Land Grant Program (Ponape), the College of the Marshall Islands (Majuro), and Kailua-Kona, where a commercial and experimental facility still operates today. Another hatchery dedicated exclusively to research operates at the University of Hawaii-Hilo.

The problems encountered were not solely due to infrastructure or basic technique but also to the consistency and reliability of production.

The Collaborative Alliance: A Collective Response

To address these challenges, the Collaborative Alliance — a network of aquaculture professionals — launched a project entitled “Filling the Gaps to Ensure the Viability of Small-Scale Tropical Mariculture Enterprises in Hawaii and the U.S.-Affiliated Islands.” Its objective: to analyze hatchery techniques on a regional scale and identify the main obstacles limiting production success.

Project partners are simultaneously conducting research to design new methods to overcome existing problems.

A Technique Now Operational but Still Being Refined

The basic hatchery technique for Pinctada margaritifera is now well established and supports the development of pearl farming across the Pacific. However, some challenges remain: researchers are working to improve larval rearing and nursery grow-out methods in order to increase profitability and production reliability.

They are also studying the seasonality of black-lipped oyster spawning to make spawning induction more reliable.

Biological and Economic Challenges

Oyster metamorphosis remains a long and unpredictable process, while early mortalities continue to occur sporadically and are poorly understood. The grow-out period requires significant labor and suffers heavy losses, particularly due to predation by Cymatium snails.

Researchers are currently exploring solutions to improve both sea-based and land-based grow-out. At the same time, a bioeconomic study of Micronesian farms and hatcheries is evaluating the cost-effectiveness of each step, from hatchery to nursery. The first results of this research will be published soon.

This project was initiated in response to two major findings: the shortage of exportable products in the archipelago and the proven success of pearl farming in Eastern Polynesia. The initiative was funded by the Australian Centre for International Agricultural Research (ACIAR).

Creation of a Hatchery and Nursery

Initial studies conducted in the Gilbert Islands revealed the very low presence of Pinctada margaritifera, the black-lipped pearl oyster, compounded by poor natural spat recruitment. This finding led researchers to prioritize hatchery production as the only viable way to develop the pearl farming industry.

In 1995, a hatchery was established on the island of Tarawa, complemented by a nursery on nearby Abaiang. These facilities have expanded significantly over the years. Today, the hatchery regularly produces large quantities of spat: during the first half of 2003, two production cycles yielded a total of 6.1 million spat.

Larval survival rates are particularly high, typically reaching between 30 and 50% during rearing. The nursery and grow-out facilities can now accommodate nearly 80,000 oysters — juveniles and adults — which also serve as a demonstration farm for staff training.

First Harvests and Project Expansion

The first experimental grafting was carried out in Abaiang in 2001, with the first pearl harvest in 2003. A second grafting, involving 10,000 oysters, was undertaken in August 2003.

Since then, project activities have been expanded to new sites within the Abaiang lagoon and other islands in the Gilberts.

A Structured Development Plan

The growth of pearl farming in Kiribati will be strengthened by the development of a comprehensive plan and the establishment of a Pearl Oyster Coordinating Committee. This plan will serve as a framework for the industry, involving the local population and integrating both technical and policy aspects of its evolution.

The Committee, bringing together relevant ministries and various institutions, will advise the government on measures to support and structure this emerging sector.

A Quota System for Sustainable Development

The management of this sector relies on a quota system designed to ensure sustainable development and prevent negative impacts on the environment. This system aims to guarantee:

• Sustainable harvesting from the natural environment
• Minimal impact of pearl farming on the marine ecosystem
• Optimal returns for the State through strict management of hatcheries and preservation of the reputation of Australian South Sea pearls to maintain high prices

A Structured Industry Generating Employment

Today, 16 companies hold operating licenses and manage a total of 572 production units supplied by natural stocks and 350 hatcheries. Together, they employ approximately 1,500 people in the remote Kimberley region of northwestern Australia.

The design, implementation, and monitoring of industry management are entrusted to the Pearling Section of the Western Australian Department of Fisheries. This department oversees wild and hatchery harvests, monitors stock status, manages disease prevention and treatment, ensures regulatory compliance, and provides public education. It also allocates and directly administers leases and licenses for pearl farms.

An Industry Facing Global Challenges

The Pearling Section also provides operational support to the Pearling Industry Advisory Committee, created under the 1990 Pearling Act, and works closely with the Pearl Producers Association, the industry’s representative body.

In recent years, the sector has experienced difficult times. The global drop in pearl prices has led to production rationalization. The allocation of marine areas to pearl farms has become a source of tension with other users in the Kimberley region.

Strengthening Environmental Obligations

The promulgation of the Environmental Protection and Biodiversity Conservation Act of 1999 introduced a new requirement: pearl farmers must now assess the environmental impact of their practices to retain their right to export pearls. Anticipating this regulation, many producers have implemented their own environmental management systems to secure the sustainability of their operations.

A Monograph to Take Stock

This monograph highlights the main challenges facing the industry and describes the solutions implemented through the current management systems.

Global production of akoya pearls has been experiencing a steady decline for several years. This downturn is mainly due to the crisis in Japan’s pearl industry, which has been hit by oyster overpopulation and diseases that have decimated much of its stocks.

In response to this situation, interest in research and development for akoya pearl production in other countries — particularly China and Australia — has been growing rapidly.

A New Testing Ground in Queensland

Australian pearl farming is currently based mainly on the exploitation of Pinctada maxima, the silver-lipped pearl oyster. However, increasing attention is being directed toward two other species, Pinctada margaritifera and Pinctada fucata, which are found in abundance in Australian waters.

A recent report details the work carried out in northern Queensland to evaluate the feasibility of producing akoya pearls from Pinctada fucata.

Valuable Data on Oyster Growth and Survival

Researchers collected baseline data on oyster growth and survival during the different stages of culture, from the larval stage to the nursery phase. They studied the best culture conditions: water quality, optimal larval density, feeding, type of nursery equipment, and stocking concentrations.

Promising Results for Pinctada fucata

This trial marks the first successful hatchery production of Pinctada fucata in Queensland. The methods used to rear this species were adapted from those already proven for Pinctada margaritifera.

During the first year of the project, more than 48,000 spat aged 3.5 months, with a mean dorsoventral height (DVH) of 12.5 ± 0.4 mm (± standard deviation, n = 50), were produced. Observations indicate that it is preferable to raise the oysters at a depth of 2 meters after their first transfer to the sea.

Once sorted, the oysters should be stocked at 20–30% of the available culture space, either in pyramid nets or in the same nets lined with finer mesh, until they reach a DVH of 50 mm. Beyond this size, they are transferred into “kangaroo pockets” or larger-mesh culture structures, with nets cleaned or replaced every eight weeks. Oysters grown individually, without forming clusters, also achieve larger sizes.

A Bright Future for Australian Pearl Farming

The results obtained are highly encouraging: in just 24 months, some specimens reached a DVH greater than 100 mm with a wet weight of 100 grams. Selective breeding trials are underway based on oyster size, and early observations suggest a promising future for akoya pearl production in Australia.

The black-winged pearl oyster (Pteria penguin) is found along the coasts of Hainan Island, the Leizhou Peninsula, and other maritime areas of the South China Sea. This large bivalve is known for its rapid growth, making it a particularly attractive species for pearl aquaculture.

Farming trials were launched about five years ago. Initially, wild oysters were collected to produce hemispherical pearls (mabé), and mature specimens from the wild were selected to serve as broodstock for spat production.

Mastered Farming Techniques

After several series of trials, researchers developed a complete farming process that includes:

• Selection and rearing of oysters
• Spawning induction
• Larval rearing
• Spat collection
• Grow-out to adulthood

This monograph provides a detailed description of each stage, from zygote to adult.

Towards the Production of Round Pearls

With sufficient reproduction achieved — first from wild oysters and later from farmed stocks — researchers have obtained enough oysters to conduct production trials.

Two companies — one based on Hainan Island, the other on the Leizhou Peninsula — collaborated in the research efforts and successfully developed an efficient technique for mabé production.

More recently, the teams have succeeded in producing the first round pearls from the black-winged oyster, marking a significant step forward for the industry. This monograph provides an overview of the techniques for producing both hemispherical and round pearls from this promising species.

The Hawaiian black-lipped pearl oyster (Pinctada margaritifera galtsoffi) is a unique subspecies, distinct from the famous Tahitian pearl oyster. Once abundant, it was traditionally used by Native Hawaiians to make fishhooks, lures, ornaments, and various tools.

Since the arrival of settlers, this oyster has been subjected to heavy commercial fishing pressure, leading to a dramatic decline in its populations. The last significant stocks, located in the reefs of Pearl and Hermes, disappeared in the 1920s after more than 100 tons of shells were harvested.

Recent observations are alarming: eighteen hours of diving yielded only 30 adult oysters, all more than 20 cm in diameter — a sign of virtually nonexistent recruitment.

Persistent Threats Despite Protection

Despite their protected status, the remaining stocks continue to dwindle, particularly in Kaneohe Bay. Population recovery is hindered by:

• Increased reef predation
• Poaching by divers
• Pollution of reef and lagoon areas
• Short viability of larvae in open culture systems

The oysters remain vulnerable to fish, octopuses, and predators such as Cymatium. Even protective cages have not been sufficient to safeguard them effectively.

A Natural and Innovative “Breeding Center”

The best strategy to replenish stocks would be to create breeding reserves bringing together large adult oysters to synchronize spawning and achieve high fertilization rates. The resulting larvae could then be carried by currents and naturally settle throughout the archipelago.

Interestingly, a commercial pearl farm can serve this role as a breeding center. With this goal in mind, Black Pearls Inc. (BPI) is developing the first Hawaiian pearl farm combining commercial production with a conservation tool.

A Historic Success

After participating in the revision of legislation on marine concessions, BPI obtained a 30-hectare concession near Honolulu International Airport. In 2003, the company harvested the first authentic Hawaiian Pearls™.

Today, a distinctive local range of pearls and mother-of-pearl jewelry is offered, giving Native artisans the opportunity to once again work with their ancestral material and adding a unique romantic charm to the islands.

Traditional sources of income in Central Pacific island nations, such as copra, are becoming dangerously scarce. At the same time, high-value natural resources — such as groupers (for the live fish markets) and sharks (for their fins, highly sought after in Hong Kong and across Asia) — are being overexploited by foreign fleets. These fleets employ outside labor, leaving few benefits for local populations.

Aquaculture: A Growing Alternative

In response to this resource depletion, aquaculture development is intensifying at various levels: from secondary school programs on outer islands to ambitious commercial projects aimed at strengthening the economic viability of isolated Central Pacific communities.

Pearl Farming: An Asset for Rural Communities

The farming of black pearls from the oyster Pinctada margaritifera appears to be one of the most promising forms of small-scale commercial aquaculture. It is already practiced in the Marshall Islands and the Federated States of Micronesia, generally as a supplementary activity to traditional sources of income.

Economic Analysis of a Small Pearl Farm

The study carried out financial projections for a farm raising 25,000 grafted oysters using the Tahitian method of suspending oysters on lines. The researchers prepared a detailed breakdown of initial investments, annual operating costs, as well as a budget and cash-flow plan.

Preliminary results indicate:

• Initial investment: USD 203,030
• Annual operating costs: USD 221,212
• Average net return over 20 years: USD 128,223 per year (based on conservative market price estimates).

Outlook and Future Publications

The authors will conduct a sensitivity analysis to assess the impact of fluctuations in prices, survival rates, grafting costs, and other production factors on profitability. The detailed results will be published in a scientific journal.

Pearl farming is now one of the main sources of aquaculture revenue in the Republic of the Marshall Islands, second only to giant clam mariculture. The black-lipped pearl oyster (Pinctada margaritifera) is found in selected atolls where it is commercially exploited.

There are currently four active pearl farms in the country, successful enough to consider expanding their production. Interest in the sector is growing, with several new entrepreneurs expressing their willingness to invest in this promising industry.

A Major Challenge: Lack of Natural Stock

The main threat to the sustainable development of pearl farming in the region remains the insufficiency of natural pearl oyster stocks. Previous studies indicate that the current stock cannot sustainably support a commercial industry and that there is a high risk of total depletion.

Experiments using natural spat collected from different atolls have produced inconclusive results.

A Turning Point with Hatchery Production

This problem has largely been addressed through the implementation of commercial-scale hatchery techniques, which now make it possible to produce spat for the entire industry.

Recognizing the potential of pearl farming as a primary or supplementary source of income for the local population, public authorities are encouraging the creation of small pearl-farming businesses to diversify the economy and reduce dependence on copra.

They are also putting in place sustainable management systems to preserve marine resources.

Outlook

This monograph provides a detailed overview of pearl farming in the Marshall Islands and outlines development prospects for the coming years, underlining the strategic role of this activity in the island economy.

Since time immemorial, India has been renowned for the beauty of its natural pearls. The country has an abundant supply of pearl oysters, particularly the akoya oyster (Pinctada fucata), found in the Gulf of Mannar, the Palk Bay, and the Gulf of Kutch.

This species is often confused with Pinctada radiata — a common but incorrect identification. The black-lipped pearl oyster (Pinctada margaritifera) is found mainly in the Andaman and Nicobar Islands.

The Beginnings of Modern Pearl Farming

Experimental pearl farming was first attempted in India in the early 1970s under the leadership of the Central Marine Fisheries Research Institute (CMFRI) at its Tuticorin center on the country’s southeastern coast.

In 1972, CMFRI produced its first cultured pearls, marking the official start of this industry in India. The institute subsequently refined hatchery techniques for rearing P. fucata (1982) and later P. margaritifera (1987).

A Growing Sector

Once sea-farming and pearl production techniques were standardized, private entrepreneurs and village associations along India’s coasts began engaging in pearl farming, paving the way for genuine local economic development.

Recent Innovations

This monograph briefly traces the evolution of India’s pearl farming industry and highlights recent innovations, such as the development of land-based pearl culture, which could further diversify production.

The pearl industry in Micronesia could become a major source of export revenue once fully developed. In French Polynesia, the export of cultured black pearls generated more than USD 100 million in 1999, inspiring other oceanic nations such as the Cook Islands to follow suit.

Micronesian countries, however, still lag behind their South Pacific neighbors, mainly because their natural environments do not provide enough oysters to supply farms on a regular basis.

A Project to Address the Shortage of Spat

In 2001, the College of Micronesia (COM) launched a project to develop a technique for producing pearl oyster spat and compensate for this shortage. The project, entitled “Development of Pearl Aquaculture and Expertise in Micronesia,” was funded by the USDA and the Office of Insular Affairs of the U.S. Department of the Interior.

The project has two main objectives:

• Develop the pearl industry in Micronesia.
• Train local human resources capable of sustaining this activity.

Phase 1: Hatchery Setup and Training

The first phase (Q1 2001 – Q4 2002) made it possible to:

• Recruit an Australian expert in hatchery pearl oyster farming techniques.
• Install a hatchery in a former warehouse at Nett Point, Pohnpei.
• Successfully carry out the first hatchery and ocean grow-out trials, producing tens of thousands of spat that are now in the grow-out phase at two demonstration farms.

Three Micronesian technicians were trained and are now able to pass on their know-how to more than 40 trainees from local communities, schools, and universities.

Phase 2: Towards Pearl Production

The second phase, launched in 2003, consists of technical evaluations and demonstrations aimed at preparing for pearl production and industry management.

The main components include:

• Expanding training in hatchery and grow-out techniques, passing knowledge on to a second generation of technicians.
• Conducting pearl production trials and evaluating grafting techniques.
• Establishing management models for the pearl industry in collaboration with regional institutions and public authorities.

Black-lipped pearl oyster (Pinctada margaritifera) spat were produced in the hatchery of the College of Micronesia (COM) at Nett Point, Pohnpei. Forty-four days after fertilization, the spat, which had settled on “tank spat collectors,” were transferred to specially constructed grow-out farms by COM.

The spat were placed in protective mesh nets with a 0.75 × 1.5 mm mesh size, suspended at a depth of 2–3 meters. After two months of grow-out, they were distributed into 48-pocket panels (4 mm square mesh), then graded and transferred into panels with larger mesh or lantern nets as they grew (at 4, 6, and 9 months).

Growth Results

Mean growth measurements (± standard deviation), based on anteroposterior length (APL) and dorsoventral height (DVH), were as follows:

• 6th month: 38.0 mm ± 7.1 (APL) and 39.8 mm ± 6.4 (DVH) (n = 206)
• 9th month: 57.4 mm ± 6.2 (APL) and 55.5 mm ± 7.1 (DVH) (n = 87)
• 12th month: 81.9 mm ± 8.1 (APL) and 83.9 mm ± 7.6 (DVH) (n = 118)

These values are comparable to those obtained in northeastern Australia by Southgate and Beer (1997) and higher than those reported by Southgate and Beer (2000) for juveniles aged 7 to 12 months (max. DVH 65.8 mm), confirming faster growth in Pohnpei. The maximum recorded DVH reached 97.6 mm.

High Survival and Consistent Results

Survival rates between 4 and 12 months, and between 6 and 12 months, were 83.2% and 91.3%, respectively. Over the course of 2002, successive trials showed remarkable consistency, with survival rates ranging from 88.9% to 98.5% depending on the monitoring phase.

The mean DVH/APL ratios of the first two hatchery-produced batches in 2002 were 1.035 (± 0.050; n = 118) and 1.042 (± 0.085; n = 139), with no significant difference (P > 0.05), confirming the uniformity of the individuals produced.

Outlook for Pearl Production

These results confirm that the grow-out method implemented in Pohnpei is effective and that the local environment is particularly favorable for the development of hatchery-produced pearl oysters.

Nucleus implantation is scheduled to begin in September 2003 to test the quality of black pearls produced from both hatchery and wild-collected oysters.

Last month, Commissioner Kevin Cleland submitted the findings of his inquiry to Deputy Premier and Minister for Planning Andrew Refshauge for parliamentary review. Opponents fear that the project will harm the environment and natural beauty of Port Stephens, restrict public use of the waterway, negatively impact the growing tourism industry, and threaten marine wildlife, including dolphins and whales.

A Project with Significant Economic Impact

Australian Radiata Pty Ltd plans to establish the farm on a small plot of land and on five deep-water marine leases. Mr. Cleland highlighted the project’s potential benefits and, while acknowledging the concerns raised, concluded that there are no ecological reasons preventing pearl oyster farming in Port Stephens.

The endemic species Pinctada imbricata will be raised from approved stocks to produce high-quality pearls of medium to small size. More than two million oysters will be seeded each year, creating 80 full-time jobs. The total value of the pearls harvested is estimated at AUD 12 million.

Lingering Concerns

Raquel Carter, a representative of the New South Wales Nature Conservation Council, reiterated that the economic and social risks associated with the project outweigh the expected benefits for the local population.

Nevertheless, Mr. Cleland recommends a precautionary approach: he acknowledges that marine animals could become entangled in aquaculture installations and calls for safety measures to be implemented. The commission also recommends rejecting one of the proposed farming sites.

Finally, the report advises closely monitoring the situation after the project’s launch and reducing or modifying certain operations should unforeseen negative impacts arise.

This project is supported by a volunteer from the Japan International Cooperation Agency (JICA), who proposed developing the farming of black-lipped oysters on the archipelago.

Osamu Taniguchi, the JICA volunteer, announced that by December, the reproductive organs of the black-lipped oysters collected six months earlier would reach maturity. According to him, the juveniles from these oysters are already in their early growth stages.

From the 70 to 80 oysters collected, thousands of juveniles can be produced. The breeding season, he noted, began in August and will end in December — a crucial period to obtain mature cells necessary for black pearl production.

Arriving in Palau last April for a two-year mission, Mr. Taniguchi brings extensive experience: he lived in the Philippines for 20 years, including 12 years dedicated to farming black-lipped pearl oysters.

Since his arrival, he has explored several areas to locate black-lipped oyster populations, which are still poorly documented in the country. He estimates it will take about two years for the juveniles to reach adulthood and another two years to obtain the first black pearls.

To achieve significant production, Palau will need to secure thousands of oysters, the Japanese specialist emphasized.

This initiative is the result of a fruitful meeting he had with the authorities of Ishigaki Prefecture last month.

According to Mr. Remengesau, pearl farming is a thriving industry in Ishigaki and would be perfectly suited to Palau’s climate. Although a similar project had been discussed in the past, negotiations had not succeeded. This year, the group behind Ishigaki’s success will travel to Palau to meet with local authorities and explore the possibility of creating a joint venture.

A feasibility study conducted by this group has identified four sites suitable for pearl farming. Mr. Remengesau noted that it takes an average of eight years to produce black pearls, emphasizing the importance of long-term investment.

Robert Reimers Enterprises estimated the value of its 2001 harvest at around USD 50,000 — comparable to Tahiti (USD 200 million) and the Cook Islands (USD 40 million).

However, the company emphasized that the lack of government support and resources dedicated to pearl farming is slowing the development of an activity that could become the country’s leading economic sector. According to Robert Reimers Enterprises, global demand for pearls is such that several pearl farms could operate simultaneously in the Marshall Islands, generating benefits for all local stakeholders.

From August 2001 to February 2002, a small hatchery and an algal culture room were put into operation at PATS. Spawning, which was induced in February, was successful, and the hatchery now has approximately 60,000 spat measuring 4 to 5 mm.

The juveniles will soon be transferred to submerged grow-out in Pohnpei’s lagoon — a key step to continue their development.

As has been customary since 1994, a session dedicated to pearl farming was co-chaired by Richard Fassler (State of Hawaii, USA) and Yu Xiangyong (Zhanjiang Ocean University, China). Presentations and posters were so numerous that some discussions had to continue in related sessions. Two themes dominated: declining sales — particularly of black pearls — and strategies for quality improvement. Students left their mark on the event: Anne-Michelle Lee and Josiah Pit (James Cook University) received the WAS Student Award for excellence in research.

China

Several presentations shed light on Chinese pearl farming. Yu Xiang-Yong recalled the boom initiated in Zhanjiang by Professor Dalen Xiong, with the first round cultured pearls in 1958, followed by a rise to 25–30 tons per year. Despite this growth, the industry faces overexploitation of stocks, loss of genetic diversity, pollution, farm overcrowding, high mortalities, high nucleus rejection rates, and poor yields — often resulting in mediocre quality.

According to Yu, solutions include stronger public involvement (research, pollution control, regulation, training). Studies are underway on genetic diversity and hybridization of Pinctada martensii (RAPD, isozymes, morphology). Triploidy shows growth advantages, and experiments with tetraploids are being conducted to produce triploids. Diversification toward P. maxima, P. margaritifera, and Pteria penguin is encouraged.

Yu also discussed advances in freshwater pearl farming with Cristaria plicata: implantation of a nucleus (7–9 mm) combined with a piece of mantle tissue, followed by 1–2 years of grow-out, resulting in production exceeding 4 tons in 2001. Hua Dan detailed the rise of Hyriopsis cumingii and the “mantle-only” technique. China now dominates this market with 800–1,000 tons per year, of which 400–500 tons are exported (Asia, Europe, Africa, USA).

Professor Aimin Wang (Hainan Ocean University) presented three approaches for producing tetraploid P. martensii: (1) inhibition of the first polar body in fertilized triploid eggs; (2) inhibition of the first and second polar bodies in diploid eggs; (3) inhibition of the first division in diploid zygotes. Although larval survival rates remain low, only method (2) has produced tetraploid juveniles, and at a very low rate (0.0625%). Wang also presented microsatellite-based selection methods to accelerate growth and his efforts to reintroduce P. maxima in Hainan.

Black Pearls

Richard Fassler emphasized the proliferation of farms in the Pacific and the opportunities they bring, while reminding participants of French Polynesia’s dominant position. Production of Tahitian pearls has exceeded promotional targets, leading to a sharp drop in prices and, according to unconfirmed reports, layoffs in the local industry. To prevent a domino effect, he recommends differentiating Tahitian pearls (colors, unique shapes) and prioritizing quality over quantity. The overexploitation of certain lagoons calls for caution, as the sector moves toward structural adjustments.

Bernard Poirine traced the Polynesian crisis: from 1.5 kg in 1972 to 11,764 kg in 2000 (+29%/year), followed by a price collapse and production decline (indicated by falling nucleus imports). He sees this as a classic case of overexploitation of a common resource leading to crisis. His models show that the economic optimum occurs at farming densities well below the maximum sustainable density. He compared management frameworks (quotas in Australia, co-management in Japan). In Polynesia, a working group is currently discussing export controls, concession policies, quality standards, and oyster densities.

Other Regions and Research

India (Ajai Sonkar) sees potential for P. margaritifera in the Andaman and Nicobar Islands, likely requiring hatchery support due to weak natural stocks.

At James Cook University (Australia), Josiah Pit tested tropical microalgae for P. margaritifera and noted the potential of Pavlova salina for larval feeding. Hector Acosta-Salmon presented a non-destructive gonad biopsy method using propylene phenoxetol (10 mm notched needle), useful for reproduction studies.

Farming Pinctada maxima in Irian Jaya

Research by Atlas Pacific Pty Ltd (J. Taylor, J. Knauer, A.-M. Lee) aims to improve South Sea pearl quality. In Australia, golden pearls have recently sold at higher prices than silver ones. In Indonesia, their proportion is higher; selecting golden donor oysters increases the share of gold pearls by +8.6%, but still leaves a high proportion of cream-colored pearls (78.8%). Conversely, silver-nacre donors yield > 98% silver-white pearls, with good proportions of rounds, pears, and buttons.

The scarcity of silver donors in Indonesia (0.3–8.9% depending on site) has led to reinforcement strategies: larval production from silver parents, followed by selection of silver oysters at 20–24 months. Growth differences have been noted: golden-nacre oysters grow faster than silver ones.

Regarding farming techniques, comparisons between bottom culture and suspended culture (1 mm mesh bags or rice bags) show more operable oysters in bottom culture but higher survival and nucleus retention rates in suspension. For nucleus selection (cost: AUD 88–165/kg), morphological analysis of P. maxima (wet weight, shell weight, width, length) indicates that wet weight is the best predictor of nucleus size and greatly improves accuracy beyond the empirical 60%.

Atlas Pacific continues to evaluate sites and depths. A.-M. Lee correlates environmental parameters and growth: depth seems to play a secondary role, while spatial and seasonal effects are more significant.

Akoya Culture in Australia

Recent successes have sparked renewed interest. Meetings have focused on P. imbricata in Queensland and New South Wales. Josiah Pit (Orpheus Island) and Wayne O’Connor (Port Stephens) report similar larval growth rates (≈ 20 days post-settlement), but faster hatchery/grow-out growth in Queensland’s warmer waters. In both states, oysters can reach ≥ 50 mm in 12 months.

The occurrence of “runts” (slow growers) was tested: when separated and monitored, they caught up, suggesting environmental rather than genetic causes for early slow growth. Regarding reproduction, peak activity runs from late spring to early autumn, with two peaks (November, March–April). Since settlement occurs only in summer (December–February), the autumn peak likely contributes little to recruitment.

One predator is a concern: the flatworm Imogine mcgrathi, found in cages and spat bags (≈ 1 oyster/month). Control protocols are effective: saltwater baths (low/high concentration) or freshwater immersion for 30 minutes for caged oysters. Salinity must be ≤ 2.5 ppm.

Mexico: A Rapidly Growing Sector

In Mexico, the industry relies on Pteria sterna and Pinctada mazatlanica (both can be hatchery-produced). Carlos Rangel-Davalos describes a method: rearing in plastic cages (3.6 × 3.6 m), grafting at 70 mm, then transferring to kangaroo nets folded over a metal frame placed on the seabed. Three technicians/90 days per batch of 10,000 oysters; three years from spat to harvest.

Restocking programs for natural banks with hatchery juveniles (previously overfished) show success, notably at La Gaviota (Bay of La Paz) thanks to fenced parks protecting oysters until 98 mm: survival rates of 8.3–21.2% after 11 months.

After several years of working with four different grafters — all reluctant to share their knowledge — BPOM (Black Pearl of the Marshalls) was delighted to welcome Berni Aquilina, a New Zealand pearl grafter. She spent three weeks at the Bikirin farm, where she grafted thousands of pearl oysters, trained ten local employees — including four from the Arno operation — and further refined the skills of three experienced technicians.

According to Virgil Alfred, farm manager, this training has transformed the team’s understanding and abilities, giving them a much deeper grasp of grafting techniques and the needs of the oysters.

Aquilina explains that she herself faced tremendous challenges when learning grafting, encountering the silence of seasoned technicians. Aware of the value of this knowledge, she is committed to passing on her skills to help island communities better manage their farms and contribute to their economic development. “With some grafters, no one was even allowed to watch them work. One worked behind a curtain, another would turn his table to hide what he was doing,” recalls Bobby Muller. With Aquilina, the tables remained visible, allowing employees to observe and learn the technique.

She stresses, however, that grafting cannot be learned in just a few days. BPOM already plans to invite her back next year for further grafting and training sessions. In addition to her work in the Marshall Islands, Aquilina also collaborates with two pearl farms in the Cook Islands, providing the same services.

When asked about the risk of losing her competitive edge by sharing her expertise, Aquilina is reassuring: “The need for grafters in the region is enormous, and it will take years of practice before the newly trained technicians reach the required level. There will be no shortage of work.”

A total of 900 pearls from this first production have been graded and will be offered for sale “in bulk.” The remaining pearls will be shipped to Malaysia, where they will be turned into pendants, earrings, and bracelets to be marketed during the upcoming Micronesian Games in July.

The farm is also preparing to welcome, in June 2002, a grafter who will harvest 4,400 already-grafted oysters and graft an additional 10,000, marking a new step in the development of local production.