Pearl Oyster Farming Research Articles

THE EFFECT OF SEASONS AND DEPTHS ON GROWTH AND SURVIVAL RATE OF PEARL OYSTER (Pinctada maxima) IN KODEK BAY, NORTH LOMBOK

<p>The pearl oyster (Pinctada maxima) farming in the West Nusa Tenggara waters in particular and in other areas, complained to the mass mortality of pearl oysters saplings on shell width between 3-4 cm. The mass mortality, allegedly as a result of changing in environmental conditions and triggered by the shift in seasons. This research aimed to determine the effect of seasonal variations in water conditions at different depth levels on growth and survival of seedlings of pearl oysters conducted on March 23, 2008 to February 22, 2009. This research was very useful for pearl oyster farming in an effort to suppress the mass mortality rates based on the appropriate level of depth and seasons. Analysis of variance showed that the seasonal factors, the level of depth, and the interaction between both factors responded very significantly on pearl oyster seedling survival. The "significant difference test" showed that the interaction between season and level of 2 m depth provided the best result with 100% survival. The similar survival rate was also found at a depth of 8 m during the transition season I and the east season. For single factor (depth), the best result for growth and survival rate was found in 2 m deep during the transition season I.</p><p>Keywords: Oyster sapling, Pinctada maxima, growth, mortality, season, depth, Kodek Bay</p>

THE EFFECT OF SEASONS AND DEPTHS ON GROWTH AND SURVIVAL RATE OF PEARL OYSTER (Pinctada maxima) IN KODEK BAY, NORTH LOMBOK

The pearl oyster (Pinctada maxima) farming in the West Nusa Tenggara waters in particular and in other areas, complained to the mass mortality of pearl oysters saplings on shell width between 3-4 cm. The mass mortality, allegedly as a result of changing in environmental conditions and triggered by the shift in seasons. This research aimed to determine the effect of seasonal variations in water conditions at different depth levels on growth and survival of seedlings of pearl oysters conducted on March 23, 2008 to February 22, 2009. This research was very useful for pearl oyster farming in an effort to suppress the mass mortality rates based on the appropriate level of depth and seasons. Analysis of variance showed that the seasonal factors, the level of depth, and the interaction between both factors responded very significantly on pearl oyster seedling survival. The "significant difference test" showed that the interaction between season and level of 2 m depth provided the best result with 100% survival. The similar survival rate was also found at a depth of 8 m during the transition season I and the east season. For single factor (depth), the best result for growth and survival rate was found in 2 m deep during the transition season I.Keywords: Oyster sapling, Pinctada maxima, growth, mortality, season, depth, Kodek Bay

An investigation of benthic sediments and macrofauna within pearl farms of Western Australia

The pearl oyster ( Pinctada maxima) aquaculture industry in the Kimberley region of Western Australia has been established for decades. However, investigation of benthic sediments and macrobenthic communities within pearl farms for this region has not taken place until now. Pearl oysters may have the potential to foul the benthic layer under the farms through the deposition of feces and pseudo-feces from the cultured oysters and fouling organisms, and the fallout of debris from the longlines that suspend the pearl oysters. This organic waste and debris can accumulate in the sediments below the oyster longlines and potentially lead to organic enrichment and even eutrophication. Other aquacultures (such as some finfish and other shellfish) have caused eutrophication of marine sediments and a concurrent change in benthic macrofauna. For two years we sampled the sediments below three P. maxima pearl oyster farms in remote regions of the Kimberley coast. Sediment core samples were taken to measure physico-chemical variables (redox potential, nutrients loads and total organic matter) while grab samples collected the benthic macrofauna (> 1 mm in size). Each farm was compared to four control locations (total = 12 control locations) within the same region. At all three pearl farms there was no indication of eutrophication (nutrient enrichment). We concluded that the variability in benthic physico-chemistry beneath pearl farms was within the bounds of natural variability at reference locations. There were also no consistent differences in the benthic macrofauna assemblages below the pearl oyster farms when compared to control locations. There was considerable natural variability of the benthic macrofauna among all locations, but especially among the reference locations. The reference locations were as different from one another as they were from the farm locations, indicating that the diversity of benthic macrofauna taxa, and their relative abundances within sediments underlying the farms fell within the range of natural variability found at these spatial scales. The importance of robust assessment of potential environmental impact of aquaculture facilities is stressed.

Development of in situ hybridisation using 16S rRNA gene to monitor black-lip pearl oyster,Pinctada margaritifera, larvae in plankton samples

In French Polynesia, the black-lip pearl oyster Pinctada margaritifera has been farmed to produce pearls since the 1980s, forming the basis of a major industry. The sustainability of this activity relies on spat collection in the lagoons. However, pearl oyster spat can be difficult to identify for the evaluation of stock variations. It is especially hard to distinguish Pinctada spp. larvae at a very early stage of development. In the present study, a whole-mount in situ hybridisation (ISH) technique was developed to allow the discrimination of larvae of closely-related pearl oyster species found in the French Polynesian atolls. Using specific ribosomal 16S-DNA sequence data, we were able to successfully differentiate between Pinctada margaritifera and Pinctada maculata larvae from 5 to 13 days old. This is the first description of a non-destructive method allowing bivalve larvae discrimination between species within this genus. The method allowed us to successfully identify P. margaritifera larvae in natural plankton samples. This result is a key step needed to develop monitoring of P. margaritifera larval distribution in French Polynesian lagoons, a procedure which will increase spat collection efficiency and ensure sustainable development of pearl oyster farming.

Spatial and Temporal Distribution of Zooplankton Communities of Coastal Marine Waters Receiving Different Human Activities (Fish and Pearl Oyster Farmings)

Seasonal changes of zooplankton communities were monitored at two coastal marine areas, Uchiumi and Fukuura Bays located at the Uwa Sea, east side of Bungo Channel. The two sites are close to each other (c.a. 20 km) with similar habitat environments, but receive different environmental stresses from aquaculture activities, pearl oyster farming for Uchiumi Bay and fish farming for Fukuura Bay. Since both bays have no inflowing river and small populations in the catchment, the impacts of different aquaculture activities on meso- and microzooplankton communities were compared. As results, Fukuura Bay showed higher ammonium and phosphate concentrations, suggesting that fish farming could accelerate eutrophication more seriously. The dominant species of mesozooplankton were similar at the two sampling sites with dominance of small coastal calanoid copepod, Paracalanus spp., but the abundances of larger calanoid species, Calanidae, Eucalanidae, Temoridae and Acartiidae, were markedly higher in Uchiumi Bay. Small cyclopoid copepods, Oithona spp. were abundant at both sites, but the densities varied seasonally, and often more abundant at Fukuura Bay. The abundances of microzooplankton including rotifers and small Oithona copepodids were higher at Fukuura Bay. Results suggest that fish farms accompanying discharge of nutrients from additional food supply for fish may seriously modify zooplankton community structure by decreasing the abundance of mesozooplankton through accelerating the eutrophication of coastal waters.

Attached microalgae contribute to planktonic food webs in bays with fish and pearl oyster farms

2 Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan ABSTRACT: Planktonic food webs are primarily dependent on organic matter derived from phyto- plankton. In coastal areas, aquaculture has accelerated in recent decades, and attached algae and invertebrates proliferate on the farming cages. We hypothesized that the organic material on the farm structures is important to planktonic food webs and that the effects of aquaculture differ between fish (fertilized) and pearl oyster farms (not fertilized). To test these hypotheses, we examined the plank- tonic food webs at fish and pearl oyster farms using stable isotopes in the Uwa Sea, Japan. We col- lected zooplankton, particulate organic matter (POM, predominantly phytoplankton), attached algae, and macroinvertebrates in July 2005 and February 2006. Based on the isotope mixing model results, the attached microalgae contributed up to approximately 70% of the copepod food sources, and the contribution of attached microalgae to cyclopoid copepods was similar to their contribution to attached macroinvertebrates. Amphipods mainly fed on planktonic detritus from microalgae that had detached from the farm structures. The contribution of attached microalgae to copepod biomass was lower on the pearl oyster farm than on the fish farm. Our results show that attached microalgae from sea farms are important food sources for planktonic food webs in areas with fish farms and that the 2 food webs, attached and pelagic, are coupled through zooplankton grazing.

ECONOMIC FEASIBILITY OF SMALL-SCALE BLACK-LIPPED PEARL OYSTER (PINCTADA MARGARETIFERA) PEARL FARMING IN THE CENTRAL PACIFIC

ABSTRACT This work provides an analysis of the economic feasibility of one of many small-scale aquaculture operations being considered, black pearl oyster farms, as one type of supplemental economic activity for outer island communities in the Central Pacific. Specifically, projections of financial performance of a small-scale 25,000 seeded pearl oyster farm using the Tahitian long-line method are being conducted. Estimates of initial capital investment and annual operating costs are being formulated, an annual cash flow and enterprise budget are being developed. Results show that initial capital investment is $202,076. Annual operating expenses are $293,726 during full operation. The largest costs contributing to annual operating expenses are seeding (46%), labor including farm owner's opportunity cost (24%), and depreciation (9%). The base model presented in this work suggests profitability over a 20-year horizon. Net returns over a 20-year farm horizon based on an 8% discount rate indicate a positive NPV of $ 102945. Sensitivity analysis on profit due to the variability of market price, survival, and cost of seed and other inputs are conducted and results presented.

The effects of aquaculture on bottlenose dolphin ( Tursiops sp.) ranging in Shark Bay, Western Australia

The increasing presence of aquaculture in coastal waters calls for a better understanding of its environmental effects. Currently little information is available on the impact of shellfish farms on cetaceans. Here we compare long-term ranging patterns of adult female bottlenose dolphins ( Tursiops sp. in Shark Bay, Western Australia) before and during full-scale pearl oyster farming operations, to determine if they were displaced. When the exact location of the oyster farm was determined, the dolphins decreased their use of that area after the farm was in place. Tracks of adult female dolphin movement near the oyster farm were compared to tracks of dolphin movement near an ecologically similar area where no oyster farm existed. Tracks near the oyster farm were less likely to enter the oyster farm itself than tracks near an ecologically similar location. This suggests that shellfish aquaculture could have a large impact on small cetaceans. The analytical techniques discussed apply broadly to aquatic and terrestrial animals.

Particulate organic matter in sixteen Tuamotu atoll lagoons (French Polynesia)

The s t and~ng stock and chemical composition of suspended particles were monitored In 16 Tuamotu atoll lagoons and surrounding oceanic water between 1983 and 1996 Temporal and spatial variability was estimated from 18 surveys performed in Takapoto. Atoll lagoon partlculate organic matter (POM) concentrations were compared using data taken during the same months (March and November) and at the same time (morning). It appears that the lagoonal particulate organic carbon concentration depends on the latltude of each lagoon. We interpret this result as an influence of the waters deriving from the Peruvian and equatorial upwellings. Phytoplankton biomass (chlorophyll) concentration was inversely related to the water exchange between lagoon and ocean. Therefore, the best atolls for pearl oyster farming seem to be those located north of the Tuamotu Archipelago and with snlall exchange with the occan. POM concentration cvas 2 to 5 tunes higher in the atoll lagoons than in the surrounding oceanlc water, wlth a hlgher C:N ratio and a lower N:P ratio. The small size of organic particles (70 '% < 3 pm) and the low contl-ibution of phytoplankton to particulate organlc carbon (POC) (S to 19%) in the lagoons must be taken into account when calculating the potential of pearl oysters, which cannot exceed the nutritional potential of Tuamotu atoll lagoons.

Trichromatic characterization of the “black pearls” from aquaculture centers of French Polynesia

In the pearl production centers of French Polynesia, which are specialized in “black pearl” production, a statistical shift in pearl color has been noted, possibly resulting from exchanges between populations of the pearl oyster Pinctada margaritifera. Spectral analyses were carried out on pearls covering the whole spectrum of currently observed colors. This paper presents a simplified method making possible a control of the pearl oyster farming and a regulation of pearl production.

アコヤガイに寄生する二世吸虫に関する研究-IV

In order to elucidate the developmental stages of the cercaria belonging to genus Bucephalus commonly found in Japanese pearl oysters, many kinds of fish living in pearl oyster farms, where the pearl oysters were heavily infected with the cercaria, were collected and examined for the presence of trematoda. 1) A species of trematoda was found in the digestive organs of the fishes, Caranx sexfasciatus and C. ignobilis, and its specific name was identified as Bucephalus various MANTER, 19401). 2) This species bears characteristic similar to those of the metacercaria which could be brought up in the body of some other small fishes or its second intermediate hosts by artificial infection of the cercaria as reported in a previous paper4). 3) The trematoda was frequently found in the carangid fish caught in pearl oyster farms heavily infected with the cercaria belonging to genus Bucephalus, while the fish obtained from cercaria-uninfected farms were always free from the trematoda. 4) The season when carangid fish heavily infected with this trematoda is closely related to the maturing season of the cercariae, especially to the time when they leave the host bivalves. Judging from the above-mentioned facts, it can be said that the trematoda, Bucephalus various, found in the carangid fish may be identical with the adult form of the cercaria living in pearl oyster, which has been reported before as Bucephalus margaritae OZAKI et ISHIBASHI, 19342).