Oyster Growth Rates Research Articles

Realized heritability estimation on growth rate of oyster, Saccostrea cucullata Born, 1778

A selective breeding programme for commercially important oyster species i.e. S. cucullata, Crassostrea belcheri, and C. lugubris, was initiated in October 1990 in Thailand. A base population of S. cucullata was produced in an oyster hatchery at Chulalongkorn University. They were reared at an oyster demonstration farm, Klong Prong, Angsila for almost 2 years. At 15 months the base population was separated into three groups (i.e. fast, medium and slow) based on their whole weights. They were used as broodstock to produce F 2. In November 1993, most of the F 2 reached market size. Means (± S.D.) of the whole weight of offspring produced from each group are significantly different with the values of 28.4 ± 7.84 (n = 112), 23.8 ± 8.46 (n = 83), and 20.3 ± 7.94 (n = 91) g, for fast, medium, and slow groups, respectively. This suggests that growth rate in this oyster species is heritable. In addition, survival rate of the fast group was relatively higher than but not significantly different from the other two groups. The realized heritability estimate for growth rate from this experiment was 0.277 ± 0.006, which means that mass selection, to increase S. cucullata production is very promising.

The age determination and growth rate of the European flat oyster, Ostrea edulis, in British waters determined from acetate peels of umbo growth lines

The age determination and growth rate of the European flat oyster, Ostrea edulis, in British waters determined from acetate peels of umbo growth lines

The influence of irradiance on the biochemical composition of three phytoplankton species and their nutritional value for larvae of the Pacific Oyster (Crassostrea gigas)

Three species of phytoplankton grown at high (HL) or low light (LL) were fed as saturating rations to laboratory-reared larval Crassostrea gigas. Larval C. gigas fed diets of HL grown Chaetoceros gracilis and HL grown Isochrysis aff. galbana grew faster than those fed LL grown cells of the same phytoplankton species. Faster growth of C. gigas larvae was consistently associated with increases in the percent composition of short chain saturated fatty acids (FA) 14:0+16:0 in the HL grown cells. There were no consistent and significant differences between HL and LL grown phytoplankton cells in their content of carbon, nitrogen, protein, lipid or carbohydrate. Intraspecific increases in percent composition of essential fatty acids (EFAs), 20:5ω3 and 22:6ω3, in the phytoplankton were not associated with improvements in the growth or survival of the oyster larvae. Oyster larvae fed diets of Phaeodactylum tricornutum with a relatively high proportion of EFAs grew more slowly than those fed C. gracilis. In this experiment the proportion of dietary EFA 20:5ω3 was negatively correlated with oyster growth rates. The faster growing oyster larvae contained relatively more of the FAs 14:0+16:0 which may be useful as measures of larval oyster condition. After a diet of one phytoplankton species for ca. 10 d, oyster larvae acquired distinctive FA profiles resembling that of their phytoplankton prey.

Growth Trial with the American Oyster Crassostrea virginica Using Shrimp Pond Water as Feed

AbstractThis study was conducted to quantify the potential of Crassostrea virginica biculture using marine shrimp pond water. It was envisioned that this biculhre could avoid cost and reliability problems associated with the mass production of algae as oyster feed. Such problems contributed to the failure of previous attempts to commercialize oyster culture.Oysters were reared in each of two flow through 310 L tanks receiving shrimp pond water from selected commercial semi‐intensive shrimp ponds. In each tank, pond water was delivered to the upper trays and flowed downward through each of two seven tray stacks. For both tanks, mean oyster growth rate (2 g/wk) and survival (79%) from seed (0.04 g) to market size (55.0 g) compared favorably with previous reports and for the first time approximated the growth projected in a 1968 engineering study by American Cyanamid (Calbo et al. 1968).Oyster growth within and between tanks indicated a relationship between biomass and exchange rates. During a 65 d controlled monitoring period mean oyster growth rates of 3.7 g/wk were achieved in upper trays of both tanks. Data are provided to estimate optimum pond water flow rate and oyster biomass relationships. The prospects for shrimp and bivalve co‐culture appear promising.

Effects of monospecific algal diets of varying biochemical composition on the growth and survival of Pacific oyster (Crassostrea gigas) larvae

Using monospecific diets of Thalassiosira pseudonana cells grown under different steady-state conditions, it was determined that higher growth rates of larval Crassostrea gigas Thunberg were obtained when fed T. pseudonana cells grown under high light. High light grown T. pseudonana cells consistently contained relatively more of the saturated fatty acids 14:0 and 16:0. Considered over three independent experiments, high light grown T. pseudonana cells were lower in protein and higher in carbohydrate than low light grown cells. Higher growth rates of larval C. gigas were obtained on diets with more of the essential fatty acid (EFA) 22:6ω3, and less of the other EFA, 20:5ω3. The relative requirements of C. gigas larvae for the essential fatty acids 20:5ω3 and 22:6ω3 are discussed. Faster growing larvae contained higher percentages of the fatty acids 14:0 and 16:0, and lower percentages of 22:2j. Oyster growth rates were correlated with their content of the fatty acids: 14:0, 16:0 and 22:2j in two experiments utilizing separately spawned batches of larvae. Fatty acid profiles are proposed as a technique for assessing larval condition. C. gigas larvae contained ten times the percent composition of the FAs 16:4ω3, 18:1ω7, 20:1ω7 and 22:2j compared with their diet. Correlation analysis suggests that the dietary source of 18:1ω7, 20:1ω7 and 22:2j was 16:1ω7. It is concluded that T. pseudonana cells grown under high light are a superior diet for C. gigas larvae in comparison with low light grown cells of the same species.

Optimum stocking density for nursery culture of Sydney rock oysters ( Saccostrea commercialis)

Growth rates of juvenile Sydney rock oysters ( Saccostrea commercialis) declined with increasing stocking density ( P<0.01) in intertidal sectionalised trays in three 3–5-month experiments. Optimum stocking densities based on maximum biomass gain results (kg/m 2) for oysters with average initial whole weights of 0.09, 1.15 and 1.56 g/oyster were obtained at densities of 15 200, 7200 and 3600 oysters/m 2, in that order. The estimated survival rate of oysters during the 12-month study was high (97.5%).

Phytoplankton biornass in relation to the surface hydrography of southern New Zealand and possible effects on the food chain

Abstract The surface distribution of salinity, temperature, nitrate‐nitrogen (N03‐N), and chlorophyll a in the southern New Zealand, Foveaux Strait region in February 1977, 1978, 1979, and 1980 was highly variable. The source of new nitrogen appears to be incursions of high‐salinity water west and east of Stewart Island. Although it seems likely that the source of this high‐nutrient, high‐salinity water is vertical, a horizontal advective source cannot be ruled out The chlorophyll a content of surface waters was not related directly to the NO3‐N concentrations. This lower food chain variability may be linked to variability in economically important species. Oysters grew twice as fast in the summer of 1978/79 as they did in 1979/80. But the mean chlorophyll a values were very similar for February of both years (2.5 and 2.2 μg 1−1, respectively). The elevated NO3‐N levels in 1979 may have resulted in much higher phytoplankton levels later that summer and resulted in the higher oyster growth rate that year. The mechanisms driving this variability have yet to be determined.

Growth of tray-cultured oysters ( Carssostrea virginica Gmelin) in Chesapeake Bay

Growth rates of cultchless oysters raised in floating trays in a shallow tidal creek of Chesapeake Bay were examined. Growth of individuals from a population of Crassostrea virginica selectively inbred for fast growth was compared to growth of spat produced from the native parent stock. The oysters grew only during part of the year (July through October) and growth did not occur during the spring season even though the environmental conditions (temperature, salinity) were similar to those during the active growing season. All animals grew quickly in floating raft culture (10–15 mm/month) during the growing periods and at a relatively constant rate with respect to length. The selected animals exhibited significantly faster growth during both growth seasons examined in the study. The rates measured during the growing season suggest that oysters could be grown to market size in 6 months of continuous active growth.

Croissance et mortalite des huitres dans la lagune de Oualidia (Maroc)

Growth and mortality of the Pacific oyster, Crassostrea gigas Thunberg, introduced into Oualidia lagoon (Morocco), were studied during the period 1981–1983. Environmental parameters of the lagoon were found favourable for a rapid growth of spats and adult oysters when reared at subtidal level. Cultch-free spats grew from 6 g (live weight) to 43 g in 1 year. Free adult oysters having an average weight of 12 g, 31 g, 46 g, 72 g, and 89 g attained 80 g, 114 g, 125 g, 162 g and 184 g, respectively, within 1 year. Oyster spats kept attached to cultch materials and reared at intertidal level showed only a 15 g weight gain in 10 months. Seasonal growth rates of oysters and spats exhibited the same seasonal trend as those observed for oysters reared in other culturing grounds from temperate regions. Survival of oysters in Oualidia seemed to be affected by the elevated water temperature in summer and autumn and by its wider diurnal variation during these periods. The spats showed mortality rates of 70–77%, the rates decreasing with growth. Mortality rates of adult oysters varied from 13 to 54% depending upon the size of the animal.

Growth of juvenile Ostrea edulis L. fed Chaetoceros gracilis Schütt of varied chemical composition

The chemical composition of Chaetoceros gracilis Schütt was altered by varying the nutrient conditions of the culture. The protein content of cells cultured in the complete f/2 nutrient medium (control) and the silicate-limited medium was similar, but cells from the nitrogen-limited medium contained ≈ 60% less protein. There was little change in amino-acid composition of cells from the three culture regimes. The lipid content of silicate-limited cells was more than twice that of either the control or the nitrogen-limited cells. The predominant fatty acids in the cells from all three nutrient treatments were 14:0, 16:0, 16:1ω 7, and 20:5ω3. The content of the essential fatty acid, 22:6ω3, in the control, silicate-limited, and nitrogen-limited cells was 0.23, 0.08, and 0.10 μg · (10 6 cells) −1, respectively. The carbohydrate levels of the silicate-limited and nitrogen-limited cells were, respectively, 1.6- and 3.2-fold higher than the control. The growth responses of Ostrea edulis (L.) juveniles fed the three cultures of Chaetoceros gracilis were a function of feeding ration. At high feeding ratios the highest oyster growth rates were obtained with the control C. gracilis diet. The relatively high level of the 22:6ω3 fatty acid in this diet is suggested as a possible explanation. At the lowest feeding rations, C. gracilis grown under silicate-limited conditions yielded the highest oyster growth rate of all three diets. When the growth responses of juvenile oysters fed various mixtures of the three C. gracilis cultures were examined, the highest oyster growth rates were obtained when 25% of the control algal cells was replaced with an equal number of nitrogen-limited cells. The results indicate that higher oyster growth rates are possible with additional carbohydrate, provided that adequate protein and essential fatty acids are supplied.

Evaluation of phytoplankton as diets for juvenile Ostrea edulis L.

Of 16 phytoplankton species tested as juvenile oyster diets, those superior to the reference diet Isochrysis galbana clone T-iso emerged with the following descending ranking: Chaetoceros gracilis Schütt, C. calcitrans Takano, Skeletonema costatum (Grev.) Cleve, Chaetoceros simplex Ostenfeld, Rhodomonas sp., and Thalassiosira pseudonana Hasle & Heimdal. The daily oyster growth rate with Chaetoceros gracilis was 1.5 to 1.8 times that with Isochrysis galbana clone T-iso. Biochemical analysis on some of the good and poor algal diets provided insight into the nutritional requirements of Ostrea edulis (L.) juveniles. Level of the essential fatty acids 20: 5ω3 and 22: 6ω3 and carbohydrate level are important factors in a good algal diet for O. edulis juveniles. Variation in the amino-acid composition among the seven algal diets analysed was small and did not explain the observed differences in oyster growth response with the diets. There was no clear trend between the protein level of the diet and the growth response of the oysters.

Preliminary studies to culture mangrove oysters, Crassostrea tulipa, in Sierra Leone

Large quantities of wild mangrove oysters Crassostrea tulipa exist in the intertidal zone of the rivers and estuaries of Sierra Leone. Typically, the wild mangrove oysters are small due to crowding and stress induced by the high ambient temperatures and lack of food at low tide when the oysters are out of water. The wild oysters measure on the average 2.5 cm and weigh 1.5 g for a 2-year growing period. Preliminary studies have been made since 1974 to identify viable culture techniques that will increase the yield (growth rate and size) of mangrove oysters. Suspended culture (rack and raft) was found to be most promising with rafts producing an average 7-cm and 7-g oyster in 7 months. Biological work summarized includes plankton, fouling and bacteriological studies. Some cost-benefit studies are also included.

Experimental deepwater culture of the Sydney rock oyster ( Crassostrea commercialis=Saccostrea cucullata) : I. Growth of vertical clumps of oysters (‘ren’)

Japanese style ren, consisting of scallop shells encrusted with small Sydney rock oysters and strung on vertical wires, were grown at 23 estuarine stations along the New South Wales coast for up to 21 months. Weight increments of ren were used to evaluate growth rates of oysters in non-cumulative (3–4 months immersion) and cumulative (6–21 months immersion) series. Oyster weight increased at a rate of approximately 10% per month, which was considered suitable for commercial production, but estimated labour costs to make up the ren were high. Mortality rate was 6.3% per 3–4 months immersion. Gaping oysters, through natural mortality, winter mortality, the haplosporidian parasite Marteilia sydneyi, and other causes, accounted for 4.5%. Broken oysters, resulting from fish and crab predation, accounted for 1.8%. Mortality caused by the polychaete mudworm Polydora websteri was negligible; only 1.7% of the 4.5% gapers showed the characteristic blisters.

A generalized growth and mortality model for assessing the economics of bivalve culture

A method is described for extrapolating the results from bivalve growth trials to cover either longer time periods or different size ranges. Examples of general size-related trends in growth and mortality rates of oysters, Ostrea edulis L. and Crassostrea gigas Thunberg are given, and their application to an economic model is described. This can be used to make projections of the likely sizes, numbers surviving and hence value of a stock, from the time of relaying until marketable size is reached. The results can be subjected to discounted cash flow analysis as a technique of project appraisal and in optimizing ongrowing schedules. The initial part of the method can be used separately in monitoring batch-to-batch or year-to-year differences in growth performance.

Seasonal changes in the effects of temperature and water flow rate on the growth of juvenile Pacific oysters, Crassostrea gigas (Thunberg)

This study, initiated because of local interest in the feasibility of using heated power plant effluents in the culture of the Pacific oyster Crassostrea gigas, sought to investigate seasonal changes in the effects of temperature and water flow rate on the growth of oysters. As a part of the study, particulate organic carbon and nitrogen suspended in the sea water entering the oyster trays were also monitored. Experiments using small (3–25-mm) cultchless spat exposed to variable controlled temperatures and flow rates were repeated seasonally. The results show profound seasonal changes in the growth rate of immature Pacific oysters. These growth fluctuations are independent of temperature and appear to be related to changes in the quantity of particulate organic material suspended in the water. Growth was minimal between November and March, regardless of the temperature, and reached a maximum in July and August. There was not a consistent growth advantage to temperatures in excess of 15°C. In fact, during periods of low food availability or at low flow rates, growth was inversely related to temperature between 10°C and 23°C. Hypothetical curves relating temperature, food availability, and oyster growth are proposed. The form of these curves, which is based on observed relationships and on similar studies involving other aquatic organisms, suggest that under ideal conditions and with high food availability maximum growth might be achieved at temperatures approaching 20°C.

THE GROWTH RATE OF OYSTERS HELD IN THE INTAKE AND DISCHARGE CANALS OF AN ELECTRIC GENERATING STATION AND IN NATURAL WATERS

ABSTRACTOysters (Crassostrea virginica) were held during the spring of 1976 in the intake and discharge canals at the P. H. Robinson Generating Station, Bacliff, Texas and in Galveston Bay at San Leon, Texas. Oysters in the discharge canal increased in weight significantly faster than in the intake canal or Galveston Bay. There was no significant difference between the weight increases in the intake canal and in Galveston Bay. No clear pattern of increase in length could be detected at the three stations. Although oysters in the discharge canal exhibited some degree of greening, the condition of the oysters from all three stations was good. The level of infection of Labyrinthomyxa was relatively low in oysters from all three stations; however, the incidence of infection was significantly greater in the discharge canal. Fouling organisms increased in weight in the discharge canal at a rate about twice that in the intake canal and Galveston Bay. Fouling could be controlled by exposing the oysters to air once each week for a period of 4–8 hr. Mortality, which was low at all stations, occurred early in the experiment and was probably due to initial culling stress. However, oysters held in the discharge canal beyond the study period died when water temperatures reached 37.5–39°C. The results of this experiment indicate that the growth rate of oysters can be significantly increased in a power plant discharge canal, provided that some means, such as cooling towers, are applied to keep high summer temperatures below lethal values.

SELECTING OYSTERS FOR FASTER GROWTH1

Growth rate (length, width, thickness, weight) of individual oysters was determined for three year classes over two growing seasons. In general the largest oysters in each year class continued to be the fastest growing, and length, width and weight were found to be highly correlated with each other. These results are discussed in terms of the following questions concerning a breeding program for faster growing oysters. (1) What trait(s) should be selected? (2) When should selection be made? (3) What effect does selection for one trait have on other traits? Simultaneously, estimates of genetic variability (heritability) have been made. The answers to the above questions plus estimates of genetic variability are necessary in order to make decisions on the best breeding methods for oysters. 1 This work was supported by a grant from the National Research Council of Canada. 2 The authors are indebted to the Canada Fisheries and Marine Services Biological Station at Ellerslie, P.E.I. for providing all material and lab space used in conducting this work.

Engineering Aspects Of Bivalve Molluscan Mariculture Progress At Delaware 1975

ABSTRACTThe University of Delaware Project is working toward development of commercial, closed‐cycle, controlled environment shellfish mariculture. As the result of several years' effort, the technical feasibility of raising bivalve molluscs from egg to market size in a recirculating system on a diet of cultured algae has been demonstrated.System optimization and cost reduction efforts are leading to an economically feasible system. Progress toward this goal has been made in several areas, including improved oyster growth rate, reduction in make‐up nutrient cost, and incorporation of a foam fractionation device for water quality maintenance and waste removal.

Growth patterns of the pearl oyster Pinctada margaritifera L. in Gazi Bay, Kenya

Culture of pearl oysters is rapidly increasing worldwide, including the western Indian Ocean. The oyster Pinctada margaritifera L., which produces the most highly valued black pearls, occurs in East Africa, a nd as been exploited there for the shell for many decades. The growth patterns of P. margaritifera from a natural population in the sheltered back-reef, and fro oysters translocated to a tidal current-swept site, both sites within Gazi Bay, Kenya, are described. The growth rate in the natural population ranged from 31.3mm year−1 (60–65mm size-class) to 7.6mm year−1 (105–110mm size-class). The von Bertalanffy growth coefficient (K), calculated with a fixed L∞ of 127.2mm, was 0.30 for the natural population and 0.38 for the translocated oysters. The mean growth rate during the north-east monsoon season was approximately double that for during the south-east monsoon season. The dailyrate of nacre deposition ranged from 1.3μm to 5.9μm (mean 3.45μm); it declined with the size of oysters and was marginally higher at the high-energy current site. At that rate, it would take approximately two years to produce a marketable cultured half pearl with a 2.5mm layer of nacre. The results of the study are relevant to the understanding of the influence of the environment on growth, and are applicable to the optimisation of growth rate of pearl oysters in the inshore region along the east coast of Africa.