Sustainability and traceability in marine cultured pearl production

For centuries, wild pearl oysters and mussels were fished in the quest for natural pearls and shell material. This eventually led to the drastic overexploitation of oyster stocks in many areas of the globe. Scientific in- novation and entrepreneurship eventually unearthed a solution: Researchers discovered a way for humans to farm pearl oysters and induce the formation of a cultured pearl. Pearl cultivation can be one of the most profitable forms of aquaculture and may be carried out in isolated islands where there are otherwise very limited economic opportunities. Pearl farming is also one of the most ecologically sound forms of aquaculture, and if managed accordingly has very little impact on the natural environment. The potential for sustainable development in island economies through pearl farming is large.
There is a positive link between environmental management and the long-term quality of pearls produced, and therefore an incentive for pearl farmers to operate in sustainable ways if they are to profit over time. The interdisciplinary approach of this dissertation has sought to produce research findings and linkages that can support the emergence of sustainable pearl production. Our main objective was to examine select sustain- ability questions in the context of pearl farming and investigate methods potentially useful in tracing pearls from farm to consumer. One hypothesis is that if sustainability metrics for pearl farms can be established and that these pearls can ultimately be traced through the supply chain, pearl consumers could further support the ecological and social benefits of pearl production in island economies. Emerging demand for responsibly produced raw materials in the jewellery industry suggests that there is indeed considerable potential for this.
The successes of the pearl industries of Australia and French Polynesia have led other Pacific nations to try and set up their own pearl industries, with mixed results. One of the newest examples of this is the Federated States of Micronesia (FSM) (Chapter 3). The challenges and opportunities of setting up a pearl industry in a country such as FSM are reviewed in this thesis: this includes a focus on production techniques, the potential for economic development, improvement of pearl quality and marketing of pearls. Pearl farming may present a great potential for Pacific communities, but being an activity that requires considerable expertise and long- term investment, must be suitably managed to achieve success. In FSM, community pearl farming takes place in a marine protected area (MPA) illustrating the potential of combining marine conservation and pearl farming. A gemmological study of Micronesian pearls showed that it was not possible to distinguish them from pearl of Pinctada margartifera from other producing countries (e.g. French Polynesia), unless they are physically separated through the supply chain, or traced otherwise.
One of the most important questions relating to pearl farming is its impact on biodiversity. This was tested by studying the influence of pearl farming on reef fish in a pearl producing atoll of French Polynesia. Reef fish are a good relative indicator of biodiversity. Because pearl farming often operates in sensitive environments, it is important to monitor its impact. This study (Chapter 4) showed that pearl farming - in the local context of Ahe- actually has a slight positive influence on fish abundance due to the shelter and food that pearl farming operations can offer reef fish. Importantly, pearl farming did not show to have any impact on reef fish diversity. Multi-factorial mixed model ANOVAs were used to determine the effects of pearl farm activity, position of sites relative to the pass and the distance of studied sites from the shore and pass on fish abundance and fish
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diversity. Samples sizes were not sufficient for statistical tests of abundances of individual species, although certain surgeonfishes (e.g. Acanthurus triostegus, Acanthurus xanthopterus) and butterflyfishes appeared to?be more numerous at pearl oyster farming sites. Our results in Ahe show that there were significant effects?on fish abundances because of pearl farming, and position relative to and distance from Tiareroa Pass. The position and distance from pass effect can be explained by physical and biological factors that differ markedly both as a whole north and south of the Tiareroa Pass and because of flushing effects with distance from the pass.
The pearl industry has not been spared ecological problems, but it is clear that if it is managed correctly it can greatly contribute to both ecological and social sustainability. Responsible pearl farming must ensure that oysters are stocked in extensive conditions and that biofouling cleaning methods are of low impact on the benthic environment. Research both in French Polynesia and Micronesia does suggest that there is an important potential for pearl farming to operate in synergy with marine protected area (MPA) strategies in a number of countries. There are few other economic activities that can contribute to environmental conservation at the same time.
Innovation is another important aspect in the pearl industry, and rapid developments in technology have in- cited some pearl farmers to innovate so as to operate more efficiently or harvest pearls of greater quality. One such innovation is the emergence of new pearl nucleus materials, such as the organic-based nuclei that we studied (Chapter 5). Our study highlights how these new nuclei are used in pearl production and investigates the resulting pearl products using gemmological methods. Both generations of these ÔnewÕ types of pearls can easily be identified using common gemmological methods.
This research has also focused on finding ways of tracing pearls. This has included developing a novel method in testing pearls: DNA fingerprinting of pearls (Chapter 6). This is the first report of oyster DNA discovered in pearls, and opens up a host of new opportunities in pearl testing. Extracted DNA from pearls was used?to identify the source oyster species for the three major pearl-producing oyster species Pinctada margaritifera, P. maxima and P. radiata. Both mitochondrial and nuclear gene fragments could be PCR-amplified and sequenced. This DNA fingerprinting method could be used to document the source of historic pearls and will provide more transparency for traders and consumers within the pearl industry. The final paper of this dissertation (Chapter 7) provides an overview of available and potential methods in tracing pearls from farm to consumer, all the way through the supply chain. Chemical marking, LA-ICP-MS, nucleus branding and other methods are reviewed. It is critical that such solutions can be feasibly integrated in pearl production and are cost efficient. Marking a pearlÕs nucleus or its surface seem the most promising options.
This study demonstrates that the sustainability potential of pearl farming is important in social and ecological terms. Metrics (e.g. impact on reef fish) can be devised so that sustainability standards for pearl farming can be developed. Other research has showed that there is a case for marine cultured pearls to be marketed as sustainable gems (Nash et al., forthcoming). In order to realise this potential, pearls also need to be adequately traced through the supply chain.