Pearl oysters in French Polynesia (original) (raw)
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The French Polynesian experience (Pearl oyster management, a manual)
In M G Bondad Reantaso S E Mcgladdery F C Berthe Pearl Oyster Health Managment a Manual Fao Fisheries Technical Paper N 503 Rome Fao 120 P, 2007
is currently the world's largest producer of cultured black pearls with exports worth U5$150 millions annually. The activity has become of prime socioeconomic importance the archipelagos with strong support and control of the govern ment. ln the mid-1980s, mass mortality ot the black-lipped pearl oyster, Pinctada margarltlfera, has occurred in several atolls and challenged the development of pearl farming activity. Consequent studies and surveys have described several pathological conditions. None of those is considered to pose significant threat to the industry. However, they are monitored by a surveillance program in order to prevent and control emerging diseases. The government of French Polynesia has developed efforts to maintain high quality of the pearls and sustain demand of the markets. This paper reviews a successful model of development based on proactive policy and cooperation among stakeholders.
Aquaculture, 2000
A model of bioenergetics of the black pearl oyster (Pinctada margaritifera) was built to simulate growth, reproduction and spawning in suspended culture at field sites in Takapoto lagoon (French Polynesia). This model was based on allometric scaling of physiological functions and scope for growth (SFG) calculations. The input functions were clearance rate (CR, l day −1 ), retention efficiency (RE, %) for each kind of particle encountered in suspended matter, pseudofaeces and faeces productions (PF and F, mg C day −1 ), excretion and respiration rate (U and R, mg C day −1 ). The assimilated carbon (i.e., SFG, mg C day −1 ) was partitioned to the three internal state variables (somatic tissue, shell and gonad) according to the asymptotic increase of the reproductive effort (ER, %) with the age. Given organic and mineral particulate matter in suspension in lagoon water (POM and PIM, mg L −1 ) and assuming that the taxonomic composition of POM was fairly constant throughout the year, the model predicted annual evolution of total tissue weight (W Tissue , g dry weight), shell weight (W Shell , g DW) and gonad weight (W Gonad , g DW) of pearl oysters at various ages. Data on tissue and shell growth, but also on gonad development of cultivated pearl oysters, acquired in 1997-1998 in Takapoto lagoon, were used to validate the model outputs. Results of the simulations indicated that the P. margaritifera growth model provided realistic growth trajectories for shell, somatic tissue and gonad, for pearl oysters aged from 1 to 4 years.
Aquaculture, 2000
Growth of the black-lip pearl oyster, Pinctada margaritifera var. cumingi, was studied for an annual cycle, from March 1997 to April 1998, in the lagoon of Takapoto atoll (Tuamotu archipelago, French Polynesia). Growth in shell and in tissue were measured every 15 days on three successive age groups of cultivated pearl oysters. At the same time, hydrobiological parameters (temperature, salinity, oxygen concentration, suspended particulate matter), known to have influence on bivalve growth, were followed each week during culture. No seasonal trend was observed in hydrobiological parameters, except for temperature which varied between 26°C and 31°C. The potential food for pearl oysters (particulate organic matter, POM, mg l −1 ) was slightly concentrated, but always available, so that, in this lagoon environment, no period seemed to be unfavourable to pearl oyster growth. Effectively, growth in shell was regular and shell did not exhibit any annual ring. Nevertheless, as it is often the case for bivalves, shell growth showed a progressive decrease with the age of pearl oyster and followed a classical Von Bertalanffy model: H=160.5 (1−e −0.038 (t−3.73) ) with H the shell height (in mm) and t the age (in months). On the other side, growth in tissue did not follow the same pattern than for shell: P. margaritifera exhibited reduced growth rate in tissue during the warm season (November-April) so that a seasonal growth model was more appropriate: W tissue =6.9/(1+e (5.58-0.208 t−0.435 sin (2π/12 (t−1.427) ) with W tissue , the dry tissue weight (in g) and t the age (in months). Several results concerning growth rates should be of interest for pearl farming. Firstly, the progressive decrease measured in shell growth rate implies, for pearl seeding operations, that the sooner the nucleus is implanted, the greater is the rate of nacreous deposition on this nucleus, and shorter is the time to obtain a marketable pearl for farmers. Secondly, exhaustive comparison, between growth rates obtained in our study and those obtained in other lagoons, tended to demonstrate that there is a small but significant variability in growth between lagoons of the Tuamotu archipelago. Further investigations need to be engaged in order to determine the most suitable sites for pearl farming in French Polynesia. Finally, comparison between growth of P. margaritifera var. cumingi and growth of other pearl oysters showed that P. maxima but also P. margaritifera var. erythraensis would also exhibit fast growth in Polynesian waters and then, would constitute potential candidates for further Polynesian diversification projects.
Aquaculture Reports
In French Polynesia, the P. margaritifera pearl aquaculture industry is spread over a vast area, as large as Europe. All the oysters for this the highly economically important activity are supplied from just a few collection lagoons, but they are grown in numerous sites across three archipelagos (Gambier, Society and Tuamotu). Many oyster transfers thus indirectly bring about grafting combinations mixing different geographic origins and production sites. This study aims to examine the impact of such graft combinations on cultured pearl quality traits. For this, six homogeneous and standardised experimental graft combinations (N = 6197) were conducted at commercial scale in the two growing locations the most frequently used in French Polynesia: Arutua atoll (Tuamotu) and Mangareva island (Gambier), using oysters supplied from by the top three collection sites: Ahe, Takapoto and Mangareva lagoons. At harvest, four main pearl quality traits: nacre weight deposition speed, pearl colour components (darkness level and green overtone), grade and shape categories were recorded by a professional sorter from the Tahiti auction and compared. Results revealed effects of the combinations of oyster origin and grow-out location, with: 1) significant origin × site interaction for nacre weight deposition speed; 2) colour variation at intra-and inter-site scales, with Ahe origin producing the most dark pearls and Gambier highest rate of the attractive green coloured pearls; and 3) higher grade categories for the Gambier origin and rearing location. These oyster-site combination effects highlight the benefit for the Polynesian pearl industry of switching from a mono-site/ company production system to a new multi-site production strategy to maximize overall cultured pearl quality expression.
Economics of Pearl Oyster Culture
This is an early draft completed towards the end of 2006 of a proposed contribution to P. Southgate and J. Lucas (Editors) The Pearl Oyster: Biology and Culture to be published by Elsevier BV. It is subject to revision and additions. †
Journal of Shellfish Research, 2016
In French Polynesia, the aquaculture of Pinctada margaritifera (Linnaeus, 1758) covers a large maritime exploitation area, spread over nearly 20 degrees latitude and longitude, with numerous pearl farms located in three archipelagos (Gambier, Society, and Tuamotu). As these archipelagos have specific seasonal temperature patterns each year, pearl oysters are subject to disparate and contrasting environmental regimes. This study aimed to examine the specificity of commercial pearl quality traits (n ¼ 2,236 samples) at the archipelago scale, in such a way as to provide preliminary data to design the most appropriate strategy for the distribution of hatchery-produced phenotypes. A large and standardized grafting experiment using the same donor phenotype was designed and carried out over six grow-out locations, covering the three archipelagos. Results revealed significant differences in commercial pearl quality traits among archipelagos, giving these groups of growing sites distinctive ''signatures'': (1) more color, less circles, and higher overall pearl grade in Gambier; (2) larger size with paler pearls in Tuamotu; and (3) darker pearls with intermediate size in Society. Characteristic differences in the environment and seasonal temperature ranges among the three archipelagos, corresponding to their distinct environmental conditions, can explain the specific variations between pearl quality traits among the sites. The strong disparities at archipelago scale should be taken into account in selective breeding programs for P. margaritifera so as to choose the most appropriate pearl oyster donor phenotype for use in each environment and thus enhance site-specific qualities for pearl production.
Ecological Consequences of Oysters Culture
Journal of Fisheries & Livestock Production, 2016
The oyster cultivation is a profitable and operationally diverse industry that has prevailed in many countries of the world. Different culture techniques have been employed from farm to farm, with growers using either, the rack and rail method, longlines, or a combination of two or more methods to grow oysters. They are grown in either intertidal or subtidal marine zones, with post-harvest activities taking place predominantly at land-based facilities. There are a number of environmental issues that are relevant to the cultivation of oysters in the coastal waters. These are typically associated with the operation of the farm or the land-based service facility. If the farm is designed or managed inappropriately, there is potential for ecological harm. Therefore, this paper reviewed some of the ecological damage associated with oyster cultivation and proffers solutions to the problems.
History, Status, and Future of Oyster Culture in France
Journal of Shellfish Research, 2009
The history of French oyster culture consists of a succession of developmental phases using different species, followed by collapses caused by diseases. The indigenous species Ostrea edulis was replaced first with Crassostrea angulata, then C. gigas. France is now the top producer and consumer of oysters in Europe, producing around 120,000 t of the cupped oyster C. gigas annually, and an additional 1500 t of the flat oyster O. edulis. Cupped oysters are produced all along the French coast from natural and hatchery spat. Various structures are used to collect spat from the wild. After a growing-on period, oysters are cultivated by three main methods: (1) on-bottom culture in the intertidal zone or in deep water, (2) off-bottom culture in plastic mesh bags in the intertidal zone, or (3) suspended culture on ropes in the open sea. The main recent development is the increasing use of hatchery oyster spat, especially triploids. Almost all oyster production is sold fresh and eaten raw straight from the shell. There is marked seasonality in sales, with the majority being made during Christmas and New Year. Abundant production and the lack of market organization induce strong competition among the production areas, causing prices to fall. Oyster farmers have developed strategies of sales promotion and regional quality labeling to overcome this difficulty. There are numerous production hazards, including environmental crises (microbiological pollution), unexplained mortality, and overstocking, and recent problems with toxic algae have disrupted oyster sales. However, oyster culture has many assets, including a coastal environment offering favorable sites for mollusc growth and reproduction. Oysters have been consumed in France since ancient times, and their culture is now well established with a concession system that favors small family firms. There is a young, well-educated farmer population, with technical expertise and savoir faire. Careful seawater quality monitoring ensures good consumer protection, and research is making innovative contributions (selection and polyploids). These points and opportunities for market expansion should bolster this industry's future, although the problem of toxic algae, probably linked to global warming and anthropogenic factors, and the threat of new diseases, pose vital questions for future research.
Aquaculture, 2000
In Solomon Islands, ''spat'' juveniles of the blacklip pearl oyster, Pinctada margaritifera, suffer high levels of mortality while on collectors, presumably due to predation by ranellid gastropods, xanthid and portunid crabs, and flatworms that also settle to the collectors from the plankton. This study tested a new strategy for reducing the mortality of spat on collectors. The existing practice of leaving spat on collectors for 6 months was compared with removal of spat after 3, 4 or 5 months, followed by the rearing of the spat in panel nets to facilitate removal of predators. In one of two field experiments, there were significantly fewer spat on collectors after six months than after 3-4 months. A similar, but non-significant, trend occurred for the other field experiment. A tagging experiment showed that survival of spat left on collectors between months 4 and 6 was 58%. By contrast, spat removed from collectors after 3 and 4 months at a mean size Ž. of) 15 mm dorso-ventral measurement DVM , and reared in panel nets, had mean rates of survival of 82 and 93%, respectively. Provided spat are a mean size of) 15 mm DVM when removed from collectors, and there is adequate husbandry of spat in intermediate culture systems, greater numbers of blacklip pearl oysters can be produced in the western Pacific by using a 3-4-month cycle for collecting spat.
Journal of Research in Biology, 2014
The present study on the biometry and fouling load of black-lip pearl oyster, Pinctada margaritifera (Linnaeus, 1758), was conducted to understand the eco-biology of these intertidal oysters so that their eligibility in the pearl culture industry could be determined. Biometric parameters viz., Anteroposterior measurement (APM), hinge length (HL), thickness (THK) and total weight (TWT) of each oyster were checked for their correlation with dorsoventral measurement (DVM) and fouling load (ΔF) separately by regression analysis. Shell length of collected specimens ranged between 16 ± 3.7- 88.2 ± 6.5 mm. Most of the P. margaritifera from intertidal regions of Andaman were confined to 61-80 mm size group. The average size of all the shell dimensions and TWT increased with increase in the shell length. The rate of increase of all the biometric parameters except TWT, declined in size range >41-60 mm. Maximum and minimum fouling load was observed during September 2011 (27.8 ± 5.1 g) and July 2012 (3.2 ± 3.7 g), respectively. Lower size groups showed maximum correlation indicating isometric growth but in higher size range, allometry was observed as the rate of increase of biometric parameters varied with increasing size range. On the basis of this study it could be concluded that if transferred to suspended culture at an early stage, these intertidal oysters, adapted to survive in harsh environmental conditions, would acclimatize more easily to the new environment and would cross the 61-80 mm size range becoming larger and thicker, a parameter favourable for pearl production.