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1.
An economic analysis of a hypothetical small‐scale marine recirculating aquaculture system (RAS) is conducted for ongrowing small, wild black sea bass Centropristis striata at the University of North Carolina Wilmington, Center for Marine Science (UNCW‐CMS) aquaculture facility in Wrightsville Beach, North Carolina (NC). The analysis is based on production data from field trials and marketing data from the sale of tank‐grown product. The growout facility consists of four 16.7‐m3 (dia. x ht. = 5.58 × 1 m) fiberglass tanks supported by state‐of‐the‐art RAS components, including particle traps and swirl separators, drum screen filter, trickling biological filter, UV sterilizer, heat pump, protein skimmer, and oxygen cone. Wild‐caught, above minimum legal size black sea bass (24.2 cm TL, 350 g, 0.77 lb) were purchased from a commercial fisherman for $3.14/ kg ($1.4011b), stocked at a density of 21.1 kg/m3, and grown to a final weight of 1 kg (2.24 lb) in 200 d at 23 C resulting in 1.8 production cycles per year. Fish were fed a commercial pelleted diet ($0.94/kg; $0.42/Ib) with a feed conversion ratio of 1.5. Final harvest density was 60 kg/m3 (0.50 lb/gal), and total harvestable weight was 3,982 kg (8,919 Ibs) of fish per cycle, or 6,760 kg (15,022 lb) per year. The economic analysis assumes that the facility owner manages and operates the system on coastal property zoned commercial/industrial, where full strength seawater is available on demand from natural sources. Under the base case scenario, initial investment in construction and equipment is $84,506 (10‐yr life), fish are grown to a harvestable weight of lkg/fish (2.24 lb/fish), product price (farm gate basis) is $10.10/kg ($4.50/lb), and breakeven price is $7.02/kg ($3.13/lb). Depreciation, fingerlings, interest paid, electricity, and feed, account for 19.6%,17.4%, 16.9%, 16.6%, and 12.3%, respectively, of total annual costs. Measures of financial performance for the base case, 10‐yr scenario are: annual return to management, $18,819; net present value (5% discount rate), $145,313; internal rate of return on initial investment, 37%; and discounted payback period on initial investment, 3.2 yr. Sensitivity analysis showed that product price changes have the largest impact on annual returns, while changes in daily growth rate, initial weight, and survival have a strong impact on financial performance. Moderate effects are seen with changes in fingerling costs, feed costs, feed conversion ratio (FCR), final weight, and interest rates.  相似文献   

2.
Growth, production and economic analysis was performed for the polyculture of juveniles spotted babylon, Babylonia areolata, and milkfish, Chanos chanos, to marketable sizes using a large‐scale production of earthen ponds in Thailand. The analysis was based on actual cost and production data from a pilot commercial‐scale farm. A total farm area of 0.8 ha was comprised of 0.3 ha grow‐out earthen ponds, a 0.4 ha seawater reservoir, and a 0.08 ha accommodation and office. Each pond was stocked with spotted babylon juveniles of 0.3 g initial body weight at a density of 200 snails m?2, and they were harvested at a 7‐month period, at an average body weight of 4.6 g for a total yield per production cycle of spotted babylon and milkfish of 9875 and 6875 kg ha?1 respectively. Based on farm data and harvest data used in this study, initial investment requirement was estimated to be $4837. The ownership cost and operating cost per production cycle were $2241 and $18 501 respectively. Total cost per production cycle was $20 742. The cost of producing spotted babylon marketable sizes in this grow‐out farm design was $6.56 kg?1. The enterprise budgets based on the price of spotted babylon at a farm gate in 2003 of $9.00 kg?1 results in gross return, net return, return to capital and management, and return on investment of $31 190, $10 448, $12 689 and 2.62 respectively. Milkfish was not calculated for any returns because they were less than marketable sizes.  相似文献   

3.
A spreadsheet model has been developed to determine the viable scale for a commercial Pacific threadfin Polydactylus sexfilis hatchery in Hawaii. The production scheme is modeled after current practices performed at the Oceanic Institute in Waimanalo, Hawaii. For a hatchery enterprise producing 1.2 million fry per year, the cost associated with raising one 40‐d‐old 1.00‐g fry is estimated at 22.01ø. The largest variable costs are in labor and supplies, which comprise 49% and 9% of the total production cost. The combined annualized fixed cost for development and equipment is approximately 12% of total production cost. At a sale price of 25ø per fry, the 20‐yr internal rate of return (IRR) is 30.63%. In comparison to the 22.01ø unit cost for 1.2 million fry production, analyses of smaller enterprises producing 900,000 and 600,000 fry per year reflected significant size diseconomies with unit costs of 27.41ø and 38.82ø, respectively. Demand to support a large scale Pacific threadfin commercial hatchery is uncertain. Since smaller scale commercial hatcheries may not be economically feasible, facilities may seek to outsource live feed production modules or pursue multiproduct and multiphase approaches to production. An analysis of the production period length, for example, indicates that the cost for producing a day‐25 0.05‐g fry is 17.25ø before tax and suggests the financial implications of transferring the responsibility of the nursery stage to grow‐out farmers. Evaluation of the benefits gained from changes in nursery length, however, must also consider changes in facility requirements, mortality, and shipping costs associated with transit, and the growout performance of and market demand for different size fry. Sensitivity analyses also indicate the potential cost savings associated with the elimination of rotifer, microalgae, and enriched artemia production. Managerial decisions, however, must also consider the quality and associated production efficiencies of substitutes.  相似文献   

4.
Split ponds are recently developed pond‐based aquaculture systems that allow intensification of catfish aquaculture. Successful industry‐wide adoption of newly developing technologies like split‐pond systems will depend upon their productivity and cost efficiencies. Costs and production performance of the following three split‐pond design scenarios were monitored in Arkansas and Mississippi: (1) research design developed at the Thad Cochran National Warmwater Aquaculture Center, Stoneville, Mississippi; (2) waterwheel design tested on commercial catfish ponds; and (3) screw‐pump design tested on commercial catfish ponds. An economic engineering approach using standard enterprise budget analysis was used to develop estimates of breakeven prices (BEPs) ($/kg) for producing foodsize hybrid catfish (♂Ictalurus furcatus × ♀Ictalurus punctatus) for each scenario. Estimates of BEPs of hybrid catfish raised in split ponds ranged from $1.72 to $2.05/kg. The cost of catfish production in split ponds was sensitive to yield, fish prices, and feed prices. Annual net cash flows from both commercial split‐pond systems were high and sufficient to make the investment profitable in the long run. Feed price, feed conversion ratio, and yield contributed the most to downside risk of split ponds.  相似文献   

5.
Aquaculture production in recirculating systems has been the focus of research and development efforts for decades. Although considerable resources have been expended on these systems in the private sector, there is a scarcity of data on the economic or engineering performance of commercial scale recirculating production systems. This paper presents the results of a computer simulation of tilapia production in a small recirculating production system. Much of the performance data has been developed at a demonstration facility at North Carolina State University. Given the assumptions of the base case simulation, the cost of producing a kilogram of tilapia in the recirculating system described is estimated to be $2.79 ($1.27/lb). The results of a model sensitivity analysis indicate that while improvements in the performance efficiency of system components did not greatly affect fish production costs, reductions in feed costs and improvements in the feed conversion ratio caused the greatest reduction of production cost of all of the operational variables investigated. The analysis further indicates that the greatest gains to be realized in improving profitability are those associated with increasing the productive capacity or decreasing the investment cost of a recirculating fish production system.  相似文献   

6.
Three intensive growout trials using Penaeus vunnumei were conducted in round ponds in Hawaii in 1987. A 337 m2 experimental pond was stocked at 100 shrimp/m2 for two trials; a 2,000 m2 commercial prototype pond was stocked at 75/m2 for one trial. In the experimental pond trials, shrimp survival averaged 88 ± 10% (SE) and feed conversion averaged 2.2 ± 0.2. Growth averaged 1.5 ± 0.3 g/week, yielding 18.2 ± 1.7 gram shrimp in 80 ± 5.5 days. Combined production in the experimental trials was 32,272 kg/ha in 174 days (from stocking of trial 1 to harvest of trial 2). Comparing these results to 1986 results (Wyban and Sweeney 1988), it was concluded that shrimp growth is not affected and production is doubled by increasing stocking density from 45/m2 to 100/m2. Pooling data from 1986 and 1987, a significant linear regression was obtained when weekly growth of shrimp above four grams individual size was regressed on mean weekly pond temperature: growth = 0.37 * temperature - 8.44, (r2= 0.41; P < 0.01). Multiple regression to examine effects of shrimp size, pond biomass, and shrimp age on the temperature-growth relationship was not significant. In the commercial prototype pond trial, survival was 67% and feed conversion was 2.0. Growth averaged 1.4 g/week, yielding 18.1 gram shrimp in 88 days. Production was 9,120 kg/ha. Individual shrimp size distribution at harvest in the commercial pond was similar to experimental pond results, indicating that shrimp growth in the two systems was comparable. Financial characteristics of a hypothetical 24 pond shrimp farm using these results were determined using an electronic spreadsheet model (hung and Rowland 1987). Feed costs were 40% of total operating costs while postlarvae and labor were 14% and 16% of total operating costs, respectively. Breakeven price (BEP) was far more sensitive to changes in revenuedetermining inputs such as survival and growth than to comparable changes in costdetermining inputs such as feed and postlarvae costs. Together these results suggest that commercial scale round pond production mimics experimental scale production and that round pond technology has commercial potential.  相似文献   

7.
Louisiana State University Agricultural Center cost estimates for single-crop crawfish production costs are analyzed for the period, 1991–2010, to determine changes in the cost components of Louisiana crawfish production. Fuel costs have contributed the most and fixed expenses the least to increased production costs, with total expenses per acre increasing by an average of 3.8% per year if land is not included and by 3.6% per year if land is included. Crawfish prices have varied greatly over the period, ranging from $0.50/lb in 1993 to $1.75/lb in 2000. Production practices used by Louisiana crawfish producers are highly variable, creating challenges for estimating representative production cost estimates.  相似文献   

8.
To improve feeding management and reduce feed cost in semi‐intensive grow‐out culture of milkfish (Chanos chanos, Forsskål 1775) in brackish ponds, the relative shares of natural food (NF) and supplemental feed (SF) ingested by the fish were microscopically quantified from their completely dissected digestive tracts sampled during 24‐h cycles in wet (June–September) and dry (December–April) seasons. Particles from rice husk, indigestible to milkfish, were used as internal markers to quantify supplemental feed. Significantly (P<0.05) more NF than SF (1.4±0.2 vs. 0.4±0.1 g kg?0.8) and SF than NF (1.4±0.8 vs. 0.6±0.3 g kg?0.8) were found during the first month of the wet and the first 3 months of the dry season respectively. Diurnal feeding patterns on SF were significantly higher at morning hours during the dry compared with the wet season. The feeding pattern of milkfish is likely to be affected by the different weather and pond conditions in both seasons. Developing a season‐specific pond fertilization management to enhance NF availability in semi‐intensive milkfish culture can help to improve the economical and ecological performance of milkfish culture.  相似文献   

9.
Freshwater prawn, Macrobrachium rosenbergii, production costs have mainly been estimated from experimental results or from limited numbers of producers. This paper discusses results from a cost of production survey sent to freshwater prawn producers in the south central United States in 2005. Feed and stocking costs were the highest variable costs and were related to the proximity of the input sources. Inorganic fertilizer cost was significantly greater for the south region while electrical costs were greater for the west region of the study area. The average prawn breakeven price covering all costs was $12.74, $14.27, $16.12, $17.18, and $14.55 per kilogram for producers in Kentucky, Mississippi, Tennessee, “Other States,” and for all respondents, respectively. Producers could decrease costs by improving yields, i.e., by increasing survival and/or weight gain, or by decreasing stocking, feed, and electrical costs; or by finding multiple uses of the equipment used to grow-out and harvest freshwater prawns.  相似文献   

10.
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.  相似文献   

11.
Five pond management strategies for Nile tilapia Oreochromis niloticus L. production were evaluated in 0.1‐ha earthen ponds in Egypt during a 145‐day production cycle. Pond management strategies developed by the Pond Dynamics/Aquaculture Collaborative Research Support Programme (PD/A CRSP) were compared with a traditional and a modified Egyptian pond management strategy. Young‐of‐year Nile (mixed‐sex or sex‐reversed) tilapia were stocked into ponds at 20 000 fish ha?1. Sex‐reversed tilapia were stocked into chemical fertilization, organic fertilization plus formulated feed and feed only treatment ponds, whereas mixed‐sex tilapia were stocked into organic fertilization plus formulated feed and chemical plus organic fertilization plus formulated feed treatment ponds. Nile tilapia yields ranged from 1274 to 2929 kg ha?1. Nile tilapia yields in organic fertilization plus formulated feed treatments were significantly greater than the yield from chemical fertilization ponds. PD/A CRSP pond management strategies did not produce significantly greater Nile tilapia yields than the traditional Egyptian system, but a larger percentage of harvested tilapia in the organic fertilization plus feed treatments were classified in the first and second class size categories compared with the traditional Egyptian system. Organic fertilization plus formulated feed pond management strategies had the highest net returns, average rate of return on capital and the highest margin between average price and break‐even prices to cover total variable costs or total costs.  相似文献   

12.
ABSTRACT

Crayfish harvest as an ecosystem service of moist-soil wetlands in the Mississippi Alluvial Valley (MAV) was evaluated using estimates of crayfish yield and operational costs to create enterprise budgets. The average daily yield of crayfish was 2.13 lb/acre (95% CI = 1.19–3.00) and yield did not differ between wetlands dominated with Red Swamp Crayfish or White River Crayfish. Four hypothetical scenarios of harvest operations revealed annual costs associated with harvesting crayfish to be $163.89–370.75/acre. Although these costs were lower than estimated costs currently associated with harvesting crayfish from fields with planted forage in Louisiana ($749.96/acre), a three-fold reduction in crayfish yield (lb/trap/day) from moist-soil wetlands resulted in an increase in the break-even selling price from $1.25/lb in Louisiana to $1.70–$3.86/lb in the MAV. Although this enterprise will likely not compete with the Louisiana rice-crayfish industry, harvesting crayfish from moist-soil wetlands may contribute to ecosystem services provided by wetlands and aid in the reduction of the quantity of crayfish products imported into the U.S. market.  相似文献   

13.
Aquaculture in the Philippines is long-established but has witnessed rapid technical change in the last 20 years with the introduction of hatchery technology and commercial feed mills changing the production possibilities for a fishpond operator. To understand the sector, a typology of brackish-water pond farming systems is constructed using multivariate methods (principal components analysis, cluster analysis). Eight input variables across all major factors of production are used in the analysis, gathered from a net sample of 136 farms in two regions in 2003. Three latent variables are described, accounting for 58% of variance in the original data: specialization; land vs. labor intensity; and feeding intensity. Five clusters (farm types) are subsequently described: extensive polyculture (40% of sample); semi-intensive prawn-oriented polyculture (11%); low-input labor-intensive farms (27%); very large, extensive milkfish-oriented farms (8%); and semi-intensive milkfish monoculture farms (14%). Implications for technical efficiency estimation and comparative study of economic indicators are discussed.  相似文献   

14.
Abstract

The risk efficient live feed system for juvenile haddock production is derived through recursive ex‐ante stochastic cost estimation. Four alternative feeding technologies are simulated to capture the economic costs associated with live feed and juvenile production and scale economies are investigated by simulating three production levels. Using Monte Carlo simulation techniques, multivariate stochastic cost functions are derived in a time‐dependent recursive production model. With the current technologies and price levels, land‐based juvenile haddock production is viable. The marginal impact, in terms of cost‐savings, to additional research on optimal feeding periods will be minimal. On the other hand, the high opportunity cost of capital used in aquaculture production, due to numerous perceived risk premia, may pose a more immediate constraint for capital formation and industry development.  相似文献   

15.
Abstract. This paper summarizes the economic aspects of production models and discusses the economic feasibilities and some marketing requirements of a proposed fisheries-aquaculture development at an ox-bow lake, isolated from the Perak River, at Teluk Intan, Perak, Malaysia. Measures of feasibility from a budgetary simulation model are expressed in terms of net present values of return (NPV), internal rate of return (IRR) and return on sale; their changes recalculated in relation to practical ranges of variations in sale prices and yields, and under conditions of normal and 20% increment in operational costs, are also expressed. Using appropriate real production data, the cage culture complex has an NPV of M$4.068 million with an IRR of 68% and return on sales of 31% at a sale price of M$10/kg and yield of 12kg/m3 (US$1.00 = M$2.30); capture fisheries integrated with livestock have an NPV of M$252410, IRR of 42% and return on sales of 18% at a sale price of M$2.50/kg and yield of 33 tonnes; the hatchery facility has an NPV of M$0.963 million, IRR of 38% and return on sales of 20% at a sale price of M$0.39/fry and yield of 2 million; and prawn pond culture has an NPV of M$314000, IRR of 43% and return on sales of 36% at a sale price of M$11/kg and yield of 2.5 tons/ha. Overall, the modular project has an NPV of M$5.596 million with an IRR and return on sales of 53% and 28% respectively. Should the operational costs increase by 20% above normal, project unviabilities are obvious at specific levels: cage culture is unviable at sale prices ≤M$8.00/kg and yields ≤10 kg/m3; capture fisheries at sale prices ≤M$1.5/kg; hatchery facility at sale prices of fry ≤M$0.30/fry; prawn culture at sale prices ≤M$8.00/kg and yields ≤2 tons/ha; and the overall project is unviable when the sale level of fisheries products drops to 80% of the normal and operational costs increase to 120%. With greater efforts at raising sales and securing better prices, and raising yields while reducing operational costs, the projects have a markedly improved economic profit.  相似文献   

16.
Nutritional profiles of 25 feed ingredients available in India were selected and compiled. Their costs were ascertained from Cochin (SW), Tuticorin (SE), and Bhubaneswar (NW), where fish/shrimp farming is traditionally practiced. Least-cost feed formulations (using the linprog toolbox in Matlab software) were attempted for catfish, milkfish, tilapia, and grouper fry specifying levels of four critical limits: Ca/P ratio, digestible energy (DE), 10 amino acid levels (where data was available), and 10 ingredients, totaling 26 constraining limits to the model. Feeds formulated for catfish fry cost US$0.066 kg?1 at Bhubaneswar, US$0.117 kg?1 at Tuticorin, and US$0.153 kg?1 at Cochin, with poultry by-product meal and hydrolyzed feather meal as the major ingredients; limiting amino acids in these feeds were methionine and phenylalanine. Feeds formulated for milkfish fry cost US$0.110 kg?1 at Cochin, US$0.108 kg?1 at Tuticorin, and US$0.072 kg?1 at Bhubaneswar; the limiting amino acids in this case were histidine and threonine. The cost of feeds for tilapia fry was US$0.207 kg?1 at Cochin, US$0.369 kg?1 at Tuticorin, and US$ 0.114 kg?1 at Bhubaneswar; the limiting amino acid was methionine. Feed formulae for fry of Asian sea bass had an LP solution containing only five ingredients for all three places. The feed formula was the same for Cochin and Bhubaneswar market prices, and the total cost of ingredients was US$0.274 kg?1 and US$0.142 kg?1, respectively. At Tuticorin market prices, the feed formula cost was US$0.397 kg?1. The feed formulae for grouper fry at Bhubaneswar and Tuticorin market prices had the same three ingredients costing US$0.114 kg?1 and US$0.321 kg?1, respectively, whereas feed formula for Cochin market price consisted of four ingredients costing US$0.280 kg?1.  相似文献   

17.
Compelled by pending regulatory rule changes, settling basins have been proposed as a treatment alternative for catfish pond effluents, but the associated costs to catfish farmers have not been estimated. Economic engineering techniques were used to design 160 scenarios as a basis for estimating total investment and total annual costs. For static-water, levee-style catfish pond facilities, sizing of settling basins is controlled by factors such as type of effluent to be treated, pond layout, size of the largest foodfish pond, number of drainage directions, scope of regulations governing effluents, and the availability of land. Regulations that require settling basins on catfish farms would increase total investment cost on catfish farms by $126–2990 ha−1 and total annual per-ha costs by $19–367 ha−1. More numerous drainage directions on farms resulted in the greatest increase in costs. While both investment and operating costs increased with larger sizes of foodfish ponds, costs per ha were relatively greater on smaller than on larger farms. For farms on which existing fish ponds would have to be converted to settling basins, over half of the cost was due to the production foregone and annual fixed costs of the pond. Requiring catfish farmers to construct settling basins would impose a disproportionately greater financial burden on smaller farms. The magnitude of the increased costs associated with settling basins was too high relative to market prices of catfish for this technology to be economically feasible.  相似文献   

18.
Detailed cost-return of freshwater prawn farming in Hawaii is estimated for farms ranging in size from a minimum of 1 acre to a maximum of 100 acres. Major factors affecting cost and revenue are discussed. Freshwater prawn farming in Hawaii is profitable at the existing average annual production of 3 000 pounds/acre and at the existing average farm price of $3.00/pound for farms that are 10 acres or larger. Smaller farms are profitable only when operated as a family venture.  相似文献   

19.
An in‐pond confinement system to separate channel catfish, Ictalurus punctatus, by size within a single pond provides an opportunity for improved growth of understocked fish in ponds with larger market‐sized fish. A barrier of polyvinyl chloride–coated galvanized wire mesh was constructed in five 0.10‐ha earthen ponds to partition the pond into one‐third and two‐third sections, while five other 0.10‐ha ponds were left as traditional open ponds for a control. To evaluate catfish performance in this confinement system, fingerlings (25 g) were stocked at 14,820/ha into the smaller one‐third section of the barrier and carryover fish (408 g) at 2580 kg/ha into the larger two‐third section of the barrier. The control ponds were stocked with the same sizes and numbers of fish in a traditional earthen pond without a barrier. Yield, survival, feed conversion ratio (FCR), growth, and economics were compared between treatments. Fingerling yields were greater in the barrier system that allowed fingerlings to be separated physically from larger carryover fish. There were no differences in yield of carryover fish, survival, FCR, or growth between the control and the barrier ponds. Partial budget analysis revealed a positive net change of $367/ha or $38,125 for a 104‐ha catfish farm (at a market price of $1.54/kg of additional stockers produced). The value of the greater weight of understocked fish produced in the barrier system was greater than the annualized cost of installing the barrier, for farmers raising fish in multiple batch. Thus, on an experimental basis, the confinement system was economically profitable; however, trials on commercial farms are needed to evaluate performance on a larger scale.  相似文献   

20.
A supplementary feed containing 30% coffee pulp was evaluated for use in the culture of Tilapia aurea in El Salvador, Central America. A comparison of the coffee pulp feed with a feed containing all of the same ingredients except coffee pulp was made with T. aurea raised in 1.0-m3 cages suspended in a fertilized earthen pond. Survival was high in all treatments and there was no significant difference in average weight gain between groups of fish receiving the two experimental feeds. Production trials were conducted in 100-m2 fish pens and in 0.05-ha earthen ponds. Pen-raised fish receiving coffee pulp feed grew faster throughout the experiment, and total production was approximately twice that in control treatments. Highest production in pens was 1.25 kg/m2 per year. Results of production pond trials using T. aurea at 9 000/ha and stocked with the piscivorous Cichlasoma managuense yielded an estimated 3 392 kg/ha per year in fed treatments and 2 049 kg/ha per year in controls. Low feed conversion (1.92) and low feed cost resulted in an increase in net annual earnings of $251.00/ha.  相似文献   

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