Experimental deepwater culture of the Sydney rock oyster (Crassostrea commercialis): IV. Pilot production of faft oysters

Rafts carrying five permanently submerged oyster trays were moored in nine New South Wales estuaries during 1976–1977 to determine how rapidly culled spat oysters (25–29 g whole weight) or seconds (29–40 g) could be grown into first grade (plate) oysters (40–67 g).In the first series of trials results were obtained from seven localities after 3 months summer growth. The average weight increase was 51%; mortality averaged 17%. A further series of trials were conducted for 3 months in autumn at four localities. Weight increases averaged 40% and mortality 8%.The growth rates calculated from weight increases were two to three times greater than those expected from normal intertidal culture traditional of Australia. The estimated time to convert spat to plate oysters was 4 months for summer and autumn crops.     

Experimental deepwater culture of the Sydney rock oyster (Saccostrea commercialis). VI. Commercial oyster cage systems

A growout cage that retains oysters, excludes predators and reduces maintenance is described; it is cut from 200 mm (8 in) steel reinforcing mesh as kitset units and then hot dip galvanised. Each cage is 2.2 m long, 0.8 m wide and 1.0 m deep (88 × 22 × 40 in) and contains five floors which are 203 mm (8 in) apart. The floors and the walls are covered with 19 mm ($\text{3}\text{4}$ in) galvanised wire mesh, or high density polyethylene plastic mesh. These cages may be slung from rafts, fitted with individual flotation or lowered to the bottom with a marker buoy; they weigh approximately 70 kg (154 lb) empty and about 220 kg (484 lb) when harvested. Each cage crop consists of approximately 2.5 bags totalling about 150 kg (330 lb), and in good growing areas three to four crops have been harvested from each cage per year. In two such crops culled spat (22–29 g whole wet weight) were converted to plate (first grade) oysters (40–67 g); in the other two, seconds (29–40 g) were converted to plate oysters. Growth rates, stocking densities and mortality data are given for 11 crops.     

Production Costs of Juvenile Penaeid Shrimp in an Intensive Greenhouse Raceway Nursery System

This analysis compared the use of an intensive nursery raceway system with direct stocking of post-larval shrimp into growout ponds. The intensive raceway system allows two crops to be produced in Texas where only one crop is feasible with direct stocking. Both investment and operational costs are analyzed for three types of greenhouses and three types of raceways where the types vary in cost and lengths of life. Three growout pond stocking densities and two farm sizes were evaluated for each combination of greenhouse and raceway type. Investment costs ranged from $142,000 for the small farm using the least expensive greenhouse and raceway and utilizing the lowest stocking density, to about $2.3 million for the large farm using the most expensive greenhouse and raceway and the highest stocking density in the growout ponds. The operational cost was $7.60 and $9.71 respectively per 1,000 one gram juveniles produced. Under technology available at the time of this analysis, direct stocking growout ponds with PIS and producing one crop per year is more profitable than stocking one gram juveniles and producing two crops per year on the Texas coast.     

Economic Evaluation of Commercial-Scale, Saltwater Pond Production of Florida Red Tilapia in Puerto Rico

An economic analysis was performed of a proposed commercial-scale 20-ha saltwater pond culture operation for Florida red tilapia in Dorado, northern Puerto Rico. The analysis was based on actual cost and production data from a commercial-scale hatchery, pilot-scale grow-out trials conducted in six 0.2-ha saltwater (avg. = 22.7 ppt) ponds at the Dorado facility and on wholesale market prices ($4.96–5.18/kg) fetched by dressed-out (gilled, gutted and scaled) product. The proposed 20-ha growout facility is comprised of 25 0.8-ha earthen ponds, each supplied with sea water, brackish well water, drainage and aeration, which account for 60.8% of the capital costs. Ponds are stocked with fingerlings (0.85 g avg. wt.) at a density of 3.0 fish/m² (30,000/ha), and are harvested at 160 and 220 d, at an average weight of 545 g for a total yield of 11,445 kg/ha per crop. Imported feed ($0.55/kg), processing and distribution ($0.50/kg) and sex-reversed fry ($0.11/fry) are the highest variable costs, accounting for 30.7%, 15.4% and 13.9%, respectively, of the total annual costs. Salaries and benefits, and depreciation represent the highest fixed costs, accounting for 8.4% and 5.5%, respectively, of the total annual costs. Under these conditions, a wholesale price of $4.55/kg results in a positive cash flow by year eight, and a breakeven price, internal rate of return (IRR), net present value (NPV) and discounted payback period (DPP) of $4.08/kg, 7.6%, ($235,717) and >10 yr, respectively, suggesting that the proposed 20-ha operation is not economically feasible under these conditions. The proposed enterprise is marginally feasible if stocking density is increased to 3.5 fish/m² while at 4.0 fish/m² economic outlook is favorable. Costs can be lowered considerably by targeting production and market variables most sensitive to profitability indices, using locally-prepared feeds, and vertically integrating hatchery and growout operations.     

Increased Growth and Production of Striped Bass × White Bass Hybrids in Earthen Ponds

Four 0.1 hectare earthen ponds were stocked with 16,500 hybrid striped bass (female Morone saxatilis × male M. chrysops ) per hectare on 22 June 1982. Mean weight at stocking was 5.2 g ± 0.10 SE. Fish were fed to satiation two or three times daily with a dry commercial salmonid diet, and the ponds were aerated mechanically during periods of low dissolved oxygen during warm weather. Survival at harvest on 6 March 1983 averaged 84.7%, and mean weight of the fish was 170.2 g ± 2.66 SE. Average weights of fish from individual ponds ranged from 149.0 to 189.7 g. The ponds were restocked on 1 April 1983 with 10,000 fish per hectare averaging 193.6 g. Ten months later, average survival in 3 ponds was 83.9% (range, 81.3–87.0%) and mean weight was 656.3 g ± 5.51 SE. Average weights of fish from individual ponds ranged from 632.5 to 690.7 g. All fish in one pond died in June as a result of an aerator failure. Standing crop at harvest in the three remaining ponds averaged 5, 504 kg/ha (range, 5,247–5,765 kg/ha). Improvements in culture techniques resulted in approximately a 138% increase in production per hectare over that reported in a prior study. Results demonstrated that hybrid striped bass offer considerable potential for commercial aquaculture in warm temperate latitudes of the United States.     

Growth,mortality and reproductive traits of diploid and triploid Pacific oysters (Crassostrea gigas,THUNBERG, 1793) in Southern Brazil

This work aimed to evaluate the whole weight (g), shell height (mm), mortality (%) and reproductive aspects (condition index and histology) of triploid (3N) Pacific oysters (Crassostrea gigas) cultivated in southern Brazil. To accomplish this, a comparative experiment was performed with a diploid (2N) control group in two cultivation sites on Santa Catarina Island: North Bay (NB) and South Bay (SB). Whole weight, height and cumulative mortality were evaluated monthly for eight months and condition index (CI) for six months. Histological analysis was performed every two weeks for four months to investigate reproductive aspects. At the end of the experiment, whole weight and height were similar for 3N and 2N oysters. However, while more growth in whole weight and height was observed in the initial phase of cultivation in NB, such growth was not detected in SB until intermediate and final grow‐out phase. At harvest, cumulative mortality in 3N oysters was similar that in 2N oysters. The results suggest that diploid and triploid oysters grown in southern Brazil have similar developmental patterns based on whole weight and height, as well as reproductive cycle. In addition, cultivation sites have more influence on growth and mortality than ploidy levels.     

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.     

Density-Dependent Pond Growout of Single Year-Class Cohorts of a Freshwater Crayfish Cherux tenuimanus (Smith) to Two Years of Age

Pond growout of Cherax tenuimanus to two years of age provided data for mean crayfish weight, surviving density and distribution of individual sizes at intervals and final harvest for 12 single year-class cohorts. Final mean size (47–156 g) was most significantly related to surviving density (4.5–0.7/m²). A hyperbolic model with a harvest date variable accounted for 89% of the variation in mean weight. The biological basis of this model is that the reciprocal of density, i.e., pond area per crayfish, represents food supply for a bottom-dwelling crayfish. By incorporating the Richards growth function, the hyperbolic model can be more realistically fitted to include the limit to potential size at very low densities. The growth-density relationship developed after an initial period of 300 days of low growth (to ∼ 10% of final size) and high mortality. Then, mean weight increased rapidly and density stabilized. Final cumulative production (1.401–3,922 kg/ha) and harvest biomass (1,110–2,991 kg/ha) both increased linearly with density. Survival of the total amount of crayfish produced was about 75% at harvest. Although cohort size distributions were positively skewed, the arithmetic mean size employed in the model was very closely and linearly related to the geometric mean of the lognormal distribution, The causal basis and assumptions of the growthdensity model are discussed in relation to resource sharing by individuals and the disproportionate influence of size-related dominance behaviour.     

Culture feasibility of eastern oysters (Crassostrea virginica) in zero-water exchange recirculating aquaculture systems using synthetically derived seawater and live feeds

The overall objective of this research project was to determine if land-based culture of eastern oysters (Crassostrea virginica) is a feasible option using recirculating aquaculture systems with synthetically derived seawater. A twelve week growout study was conducted in a closed-loop recirculating system with zero discharge using synthetically derived seawater. Two species of marine microalgae (Chaetoceros spp. and Isochrysis spp.) were cultured as oyster feed. Oysters were batch fed daily and amounts of algae cells offered to oysters were monitored. Overall, oyster survival remained greater than 99% and growth was steady and averaged 1.3, 1.1, and 0.33 mm per week for length, width, and thickness, respectively. Mean weight increased an average of 0.39 g per week. The means to maintaining suitable water quality was nitrification and supplementation of calcium to maintain ambient levels representative of their natural environments. Data collected is also useful for those who wish to study oysters in controlled environments or for genetic and/or breeding programs.     

Experimental deepwater culture of the Sydney rock oyster (Crassostrea commercialis = Saccostrea cucullata): II. Pontoon tray cultivation

Pontoons made from plastic pipe were tested as an alternative to racks for deepwater culture of the Sydney rock oyster. The growth and mortality of oysters permanently suspended in water on trays beneath floating pontoons were compared with oysters on trays in an intertidal zone. For both culled spat (30–31 g whole oyster weight) and seconds oysters (37–39 g) beneath pontoons the growth rate, measured by weight increases, was three times that of oysters on intertidal racks over a 5-month period. Mortality (from unknown causes) was higher beneath the pontoons. The mean mortality of spat oysters was 40% compared with 24% on the intertidal trays, and for seconds oysters was 51% compared with 34%.     

Production Economic Analysis of Black Sea Bass Juveniles to Support Finfish Mariculture Growout Industry Development in the Southeastern United States

A pilot-scale finfish mariculture hatchery was established at the University of North Carolina Wilmington. In 2011, research-based hatchery protocols were scaled up to produce 37,000 advanced (1–5 g) black sea bass fingerlings. Based on engineering, biological, and cost data from operating the pilot hatchery, an economic analysis of a hypothetical commercial scale black sea bass hatchery operation was conducted. The financial performance of two alternative facilities that produce 97,200 5-g and 388,800 1-g fingerlings per year over a 30-year project life showed cumulative net present value (NPV) of $445,000, and $3,168,000, modified internal rates of return (MIRR) of 6.52% and 10.52%, and per unit breakeven prices of $1.67 and $0.47, respectively. Sensitivity analyses showed that final stocking density was critical to financial performance. Fingerlings were supplied to startup growers in NC and in VA, and market-size fish from these growout facilities were distributed (live or whole on ice) to premium-value markets on the eastern seaboard. This pilot hatchery is enabling new farmers to access fingerlings, establish growout technology and understand market value and demand.     

Evaluation of Reduced Fish Meal Diets for Second Year Growout of the Largemouth Bass,Micropterus salmoides

Development of efficient cost‐effective diets is a critical component in the refinement of production technologies for the largemouth bass, Micropterus salmoides (LMB). One of the first steps in reducing feed costs can be to decrease the amount of fish meal in the diet. The objective of this study was to evaluate reduced levels of fish meal, and a least‐cost formulation diet, for second year growout of LMB under practical pond conditions. Twelve 0.04‐ha ponds were stocked with juvenile LMB (210.1 ± 3.3 g) at a stocking density of 8650 fish/ha (350 fish/pond). Each pond was randomly assigned one of the four dietary treatments with three replicate ponds per treatment. The three experimental diets contained varying levels of fish meal. Diets FM‐45, FM‐24, and FM‐8 contained 45, 23.5, and 8% fish meal, respectively. In diets FM‐24 and FM‐8, fish meal was replaced by varying levels of poultry by‐product meal, soybean meal, and blood meal. The fourth diet was a commercial salmonid diet widely used as a LMB growout feed (Nelson and Sons, Inc., Silvercup ^TM , Steelhead, Murray, UT, USA). This diet served as a commercial control (CC) and contained 46% crude protein. The experimental diets were formulated to be isonitrogenous and isocaloric with the CC diet and were fed once daily to apparent satiation for 180 d. At harvest, there were no significant differences between treatments ( P > 0.05 ) in terms of survival, which averaged 95% overall. Mean weights of fish fed the three experimental diets FM‐45, FM‐24 and FM‐8 were not significantly different ( P > 0.05 ) and averaged 518, 546, and 529 g, respectively, but were all significantly greater ( P≤ 0.05 ) than those fed the CC (488 g). Feed conversion ratio (FCR) of fish fed the FM‐45 and FM‐8 diets (1.43 and 1.46, respectively) was significantly greater ( P≤ 0.05 ) than those fed the FM‐24 diet (1.34). The FCR of fish fed the CC diet (1.39) was not significantly different ( P > 0.05 ) from fish fed other diets. Feed cost per unit of weight gain ($US/kg) was significantly lower ( P≤ 0.05 ) in fish fed the FM‐24 and FM‐8 diets ($0.73 and $0.72/kg, respectively) than in fish fed other diets. Feed cost per unit gain of fish fed the FM‐45 diet ($0.83/kg) was significantly lower ( P≤ 0.05 ) than those fed the CC diet ($1.04/kg). There were no significant differences ( P > 0.05 ) in dress‐out percentages or proximate composition among fish fed the four diets. This study indicates that fish meal levels in feeds used for the second year growout of LMB can be reduced to ≥ 8% of the formulation without reducing survival or growth and without negatively impacting body composition.     

Paddlewheel Effects on Shrimp Growth, Production and Crop Value in Commercial Earthen Ponds

The effects of continuous paddlewheel operation on shrimp growth, yield and crop value were studied in Hawaii. Six 0.4 ha earthen ponds were stocked with Penaeus vannamei at 25 postlarvae/m². Three ponds served as controls with no mechanical aeration or mixing. Each of the other three ponds had two 1 hp paddlewheel aerators (3.7 kw/ha) running continuously throughout the five month trial (29 April-8 October 1986). All other management factors were applied uniformly.
Daily water temperature and use were significantly different between treatments. Paddlewheel ponds had lower water temperatures (28.3 vs. 28.5 C) and lower water use (0.8% exchange per day vs. 2.2% exchange per day) than control ponds.
Faster shrimp growth in paddlewheel ponds was evident in week 8. At week 14, mean shrimp body weights and growth rates were significantly greater. Shrimp at harvest were 21.2 ± 2.6 g in paddlewheel ponds versus 15.3 ± 2.6 g in control ponds. Mean shrimp production was 2,852 ± 222 kg/ha in paddlewheel ponds compared to only 2,061 ± 558 kg/ha in controls. Mean crop value was $13,719 per pond per crop for paddlewheel ponds versus $9,111 for control ponds. Hence, paddlewheels afforded an increase of 42% in net crop value after subtracting purchase and operating costs.     

Production of the Freshwater Prawn Macrobrachium rosenbergii Stocked as Juveniles at Different Densities in Temperate Zone Ponds1

Juvenile freshwater prawns Mucrobruchium rosenkrgii (mean wet weight = 0.75, 1986 or 0.17g, 1985) were stocked into 0.06–0.07 ha earthen ponds at densities ranging from 39,536 to 118,608/ha during two separate growing seasons. After growout periods ranging from 135 to 142 days, survival was from 54.3% to 89.9% (x = 77.0%). Mean prawn weight at harvest ranged from 15.0 to 44.3g and decreased with increasing stocking density. The larger stocking weight of prawns was associated with harvest weights that were 16.8 to 39.6% greater than those achieved with the smaller stocking weight at comparable stocking densities. Stocking of juveniles of the proper size and the effective management of the social structure of M. rosenkrgii appear to be critical to the success of intensive pond culture in temperate climates where the length of the growing season is restricted.     

Commercial assessment of growth and mortality of fifth-generation Sydney rock oysters Saccostrea glomerata (Gould, 1850) selectively bred for faster growth

The Sydney rock oyster Saccostrea glomerata (Gould, 1850) industry acquired hatchery-produced spat selected for faster growth for the first time in January 2004. Selectively bred and non-selected (Control) spat produced concurrently were used to compare performance when grown under commercial conditions. Spat were distributed to farmers in seven estuaries in New South Wales. Individual farmers cultivated these oysters using their own techniques and growth and mortality were recorded quarterly. At each site, the two oyster types were cultivated using the same culture method, location and density. Growth was compared when oysters were 27 months of age. At this time, selectively bred oysters were significantly larger and heavier than Control oysters. The same result was obtained when oysters were compared at the point in time when selectively bred oysters had reached 50 g at each site. No significant difference was found for cumulative mortality between the selectively bred oysters and Control oysters across all sites. However, the seven sites had significantly different levels of cumulative mortality. Overall, the performance of selectively bred oysters was superior to the Control oysters and selectively bred oysters reached the 50 g bench mark within 29.3 months when averaged across all sites.     

Effect of Stocking Weight and Stocking Density on Production of Hybrid Striped Bass (Sunshine) in Earthen Ponds in the Second Phase of a 2-Phase System

Sunshine bass from Phase I or pond production were graded into two weight classes, 3 and 5 g, and stocked into experimental earthen ponds at a density of either 8,649/ha or 11,120/ ha in a 2 × 2 factorial design. After stocking, the fish were fed a commercially manufactured feed (43.0-45.5% crude protein) twice daily to satiation for 17 mo. At harvest, mean survival ranged from 67.4 to 84.8% but was highest for the fish stocked at 5g. Average production Tor ponds stocked at 8,649/ha and 11,120/ha, regardless of stocking weight, was 4,506 kg/ha and 5350 kg/ha, respectively. Production and percentages of assigned weight classes were not significantly different among treatments as a result of wide variation among replicates. Using size-dependent market prices assigned to the different harvest size groups, an economic analysis revealed gross receipts, variable costs, and total costs for the 11,120/ha 5-g treatment. Net returns were not significantly different among the four treatments due to large variation among replicates per treatment. These results confirm that the traditional phase II of pond production can be eliminated in favor of a direct stocking of phase I fish into a single production phase and economically competes very well with traditional three-phase growout management. The potential reduction in turnover time of production units achieved through the direct stock practice is an efficiency trait that should translate into significantly higher returns and a greater profit over the long term. Further reduction of stocking density combined with a stocking weight greater than 5 g should translate into greater proportion of larger, higher valued fish at harvest and a growout period of 18-20 mo, rather than the 24-30 mo traditionally needed for the combined phase II and phase III of production.     

Varying the timing of oyster transplant: implications for management from simulation studies

The transplanting of oysters from one ground to another is a common practice in the oyster industry. In Delaware Bay, for instance, oysters are typically transplanted from upper-bay low-salinity seed beds onto lower-bay leased grounds for growth and conditioning before market. The higher salinity on the leased grounds, however, also favours higher losses to predation and disease. A coupled oyster–Perkinsus marinus–predator model was used to investigate how varying the timing of transplant affects the ultimate yield of Eastern oysters, Crassostrea virginica, in Delaware Bay. Simulations were run in which oysters were moved from seed beds to leased grounds in November, January, March, April and May. The number of market-size (≥ 76 mm) adults available for harvest in the following July to November was compared for populations undergoing mortality from predation (crabs, oyster drills) and/or disease (Perkinsus marinus). In all simulations, the abundance of market-size oysters declined between July and November. However, transplanting oysters in November resulted in the largest yield of market-size oysters for all harvest times; transplanting in May resulted in the smallest yield. The autumn transplant allows oysters to benefit from the larger spring phytoplankton bloom over the leased grounds in the lower estuary. The effect of varying the season of transplant was most noticeable if oysters were harvested early (July or August). In all simulations, transplanting resulted in a higher abundance of market-size oysters than direct harvest from the seed beds. Direct harvest would rarely be advantageous if the cost of transplant were insignificant and the relative rates of mortality were as stipulated. However, a May transplant is only moderately better than a direct harvest and the economic benefits of either option are likely to be determined by the cost of transplanting and the mortality associated with the process. In the same vein, the decision as to when to harvest relies on balancing the increased price obtained for oysters in the autumn with the increased loss owing to predation and disease. Awaiting an autumn harvest is clearly much riskier if the principal source of mortality is disease rather than predation, because disease mortality is concentrated on the market-size oysters and is greatest in the autumn.     

The effect of mesh covers on the survival and growth of Crassostrea gigas Thunberg grown on the sea bed

Growth and mortality were measured in samples of Crassostrea gigas planted in trays on the beach at 4.5, 7.5 and 20% exposure. The oysters were graded by live weight into < 1, 1 2, 3–4, 5 6 and 8–10-g groups at planting. Three levels of protection were provided: none, 36-mm and 12.5-mm mesh. Five separate trials of 41–108 days covered about a year.Mortality decreased with increasing size of oyster at planting and with increasing degree of cover. On average, oysters of < 1 g and without cover showed 50% survival over 30 days, while oysters of 3–4 g protected with a 12.5-mm mesh showed 97% survival. Neither seasonal variation in survival nor variation related to exposure was detected. Unprotected oysters grew to a smaller size than protected oysters and those at 20% exposure grew less than those at 7.5 or 4.5% exposure. It is probable that the two sizes of mesh provided protection against interference and predation by the shore crab Carcinus maenas.The combined results of the trials indicated that the standing stock at the end of about 6 months, which included the summer, obtained from laying 100, 0.6 g oysters at 4.5% exposure would be 564 g and 99 g with 12.5-mm mesh and no protection, respectively.     

Premiers resultats de l'elevage en cages de Tilapia nilotica (L.) dans le Lac Kossou,Cote d'IvoirePreliminary results of cage rearing Tilapia nilotica (L.) in Lake Kossou,Ivory Coast

The experimental rearing of T. nilotica in 1-m³ cages floating in Lake Kossou, Ivory Coast, was performed between March 1974 and April 1975. The fish were fed water-stable pellets (24.7% protein), the daily ration generally varying between 6 and 3.4% of the ichthyomass present. Fingerlings (9–55 g each) were stocked at densities of 200–400 fish/m³. They reached commercial size (more than 200 g) within 4–6 months, depending on the biomass present in the cage (stocking density and average individual weight of fish), as well as on limological conditions. The average annual mortality was 5.9%. Annual production varied from 36 to 64 kg/m³. The feed conversion rate averaged 2.8. A reduction of the daily ration for fish larger than 40 g reduced this value.Fingerlings should average at least 20–30 g in weight at initial stocking of the cage. Two crops a year can then be easily realized. If only male fish are reared, three harvests per year appear to be possible, increasing the annual cage production of fish close to 200 kg/m³ with proper management.The possible development of T. nilotica cage culture is actually hampered due to the lack of adequate fish feed available commercially, and to the lack of sufficient quantities of calibrated fingerlings throughout the year.     

Carbon, nitrogen and phosphorus budget in shrimp (Penaeus monodon) culture ponds in eastern India

Nutrient budget for shrimp (Penaeus monodon) culture was performed in ten culture ponds (0.4–1.0 ha) in Orissa, India, at stocking density of 10.0–22.10/m². The average initial body weight of shrimps was 0.02 g. The culture period was for 4 months. Feed was the main input of nitrogen (N), phosphorus (P) and organic carbon (OC). The FCR varied from 1.35 to 1.75. At harvest time, the average weight of shrimps varied from 28 to 32 g. Total N, P and OC applied to these ponds through all the inputs ranged from 106.64 to 292.63, 23.17 to 57.55 kg and 763.10 to 1,831.20 kg per crop, respectively. Feed alone accounted for 94.43–95.03 % total N, 91.92–95.36 % total P and 80.33–92.48 % total OC, respectively. The harvest of shrimp accounted for recovery of 25.45–36.88 (av. 30.12) %, 10.07–12.94 (av. 11.16) % and 15.80–20.81 (av. 18.01) % of added N, P and OC, respectively. N, P and OC accumulated in sediment were 49.11, 64.07 and 64.82 %, respectively, of total nutrient retention in the culture system. Unaccounted N, P and OC were 13.29, 21.83 and 18.14 %, respectively, of the total nutrient retention in the system. N, P and OC outputs in the discharged water during harvest were 7.48, 2.94 and 2.03 %, respectively.