ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00006.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00007.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00008.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTCalcification of the new exoskeleton is the culmination of a successful molt in crustaceans. This study showed that inMacrobrachium rosenbergiicalcium present in the intermolt exoskeleton is moved internally as the molt approaches. Cyclic variations in the calcium concentrations of hemolymph, hepatopancreas and exoskeleton occur between successive intermolt periods. During premolt, hemolymph calcium concentration increases from an intermolt level of 7.67 to 14.8 mmole Ca+2liter‐1while in the hepatopancreas the change is from 0.77 to 1.22 mmole Ca+2·g dry wt‐1. An increase in calcium concentration of the exoskeleton appears to occur over this period (from intermolt 2.92 to 6.68 mmole Ca+2· g dry wt‐1). Thus, there is a mobilization of calcium to internal storage sites during premolt. Both the hemolymph and the hepatopancreas store calcium during premolt. Hemolymph and hepatopancreas stores are exhausted b the mid‐postmolt phase, falling to a minimum of 4.61 mmole Ca+2liter‐1and 0.31 mmole Ca+2·g dry wt‐1, respectively, while total calcium increases, from 0.56 to 1.39 mmole ·g dry wt‐1. The molting process causes a total calcium deficit that must be repaid from internally compartmentalized stores or from some external calcium source. Although internal sources of calcium are important for postmolt calcification inM. rosenbergii, our study indicates that additional uptake of calcium from freshwater may be necessary for complete calcification o

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00009.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTWater stable, uniformly14C radiolabeled, chemotactically‐active bacteria‐laden, artificial detritus was formulated by a rapid, simple method and used to follow the assimilation of bacterial macrommolecules into the foregut, midgut and tail tissue of aquarium‐acclimated freshwater prawns,Macrobrachium rosenbergii(de Man) in time course experiments under conditions of starvation, heavy supplemental feeding and sudden crowding. Over a 24‐hour time course with starved prawns, the proportion of the label assimilated into lipid in the midgut and tail tissue increased 12.3% and 8.0%, respectively, with decreased proportions of the label in carbohydrate in the midgut and protein in the tail tissue. Starved prawns incorporated similar proportions of the label in carbohydrate and protein of the midgut as did heavily fed prawns but shunted a larger proportion of the label into lipid. Protein was catabolized in order to synthesize lipid and appeared to be used as an energy source. Suddenly crowded prawns greatly elevated the amount of radioactivity proportioned into carbohydrates and lipids of the midgut at the expense of greatly lowered protein activities.The formulation prepared here, which appears chemotactically and visually active as artificial “fish feces,” may have wide applicability in many aquaculture pond ecology and nutrit

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00010.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTDuring 1981, pond culture trials with prawns,Macrobrachium rosenbergii, were conducted with 7 private farmers in order to obtain information on the potential for prawn farming in South Carolina. Some farmers were able to control water quality while other farmers had little or no ability to modify pond environmental conditions. Seed stock, feed, management, and harvesting assistance were provided by research personnel, while daily monitoring of pond conditions and feeding were the responsibility of the farmers.Eight ponds (size range 0.04‐0.41 ha) were stocked with small juvenile prawns (mean weight 0.29 g) at densities of 4.3/m2(43,000/ha) or 6.5/m2(65,000/ha). An additional pond, containing hung webbing to increase habitat area, was used in a high density rearing trial and stocked at a density of 19.5/m2. Growing periods ranged from 125 to 173 days during which time most farmers encountered some serious problems (predators, competitors, low dissolved oxygen levels, etc.). In the lower density trials (4.3 and 6.5/m2) production averaged 573 kg/ha (range 155–900 kg/ha) while survival averaged 44.2% (range 13.4–67.9%). Feed conversions ranged from 1.84 to 7.40 and averaged 3.34. The high density trial resulted in a production rate of 1,902 kg/ha, a survival rate of 51.2%, and a feed conversion of 2.4.Disposition of the prawn crops included: 1) direct sales to customers; 2) marketing through a farmer‐owned restaurant; and 3) retention of a portion or all of the production to substitute for the purchase of marine shrimp. Direct sales to consumers offers a number of advantages and may be the most suitable market for the predicted near‐term level of p

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00011.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThree marketing approaches were investigated for small‐scale aquaculture of prawns: 1) seafood retail markets, 2) seafood restaurants, and 3) direct sales to consumers. A market test with locally produced pond‐reared prawns was conducted in four seafood retail stores and seven seafood restaurants in South Carolina. Prawns, sold as ungraded tails at prices ranging from $8.79‐11.01/kg, were highly saleable in the retail markets. All retailers indicated that they would add this aquafood to existing product lines and stated a preference for fresh prawns in the medium size category (78–110 tails/kg).Restaurants prepared the prawns as sauteed, steamed, broiled, stuffed, and microwave‐oven cooked. The prices charged for the prawn dinners ranged from $5.95 to $12.00 per serving. Five of the seven seafood restaurants who participated in the marketing trials indicated that they would purchase prawns for their restaurant operation if a suitable supply were available. Depending on the entree, prawns might be marketed as tails or as whole animals in the seafood restaurant trade.Some prawn producers who participated in cooperative rearing trials during 1981 sold their crop directly to consumers as ungraded prawn tails at prices of $10.90 and $13.20/kg. This marketing approach greatly reduces the producer's costs for processing, packaging, storage, and transportation. In addition, direct consumer sales have fewer restrictions in regard to: size of the product; volume of orders; and packaging, as compared to purchases by seafood restaurants and retail markets. For the predicted near term production of prawns in South Carolina, this marketing approach appears most a

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00012.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTNeither feeding rate nor feeding frequency appear to affect protein digestibility in the freshwater shrimp,Macrobrachium rosenbergii. A feeding frequency of twice daily resulted in a significant increase in food consumption compared to feeding once or 3 times daily. Apparent protein digestibility from a diet containing menhaden meal as the primary protein source ranged from 83.3% to 87.7% based on the chromic oxide method. Those values were within the ranges published on other crustacean species for fish meal and other proteins.

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00013.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTThe feasibility of polyculturingMacrobrachium rosenbergiiandTilapia aureawas examined in 500 m2earthen ponds in central Texas. Monoculture of each species was also undertaken to provide comparative data. Water quality was monitored to determine its influences on survival, growth and production of the culture species.Production of freshwater shrimp in ponds in central Texas was similar to that obtained in other temperate regions of the United States where similar stocking densities, feeding and initial sizes have been employed. At a density of 9 shrimp per m2, average production was 1120 kg/ha. Polyculture increased total production above that obtained from shrimp alone. At stocking rates of 9 shrimp and one fish per m2, total production reached 2240 kg/ha. Combining fish with shrimp resulted in a recognizable but non‐significant reduction in shrimp growth and survival. Competition for food appeared to be the primary interaction between the two species. Increased stocking density increased production and reduced average size.Partial budget analysis indicated that shrimp‐tilapia polyculture had a higher net return than shrimp monocult

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00014.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

ABSTRACTFeeding trials were conducted withMacrobrachium rosenbergiito evaluate corn silage as a nutrient source for prawns in the pond environment. Cages were placed in a commercial pond and stocked with juvenile prawns at a density of 10 animals/m2. Cage bottoms were buried in the pond mud, allowing animals access to the detrital layer. Diets of commercial prawn pellet, corn silage, and a 50:50 pellet and silage mix were fed at rates of 2.5% and 5% (dry weight basis) biomass per day. Control cages received no applied feed. Diets were isocaloric and growth was measured as weight gain. During the 10‐week trials, animals receiving the commercial pellet and the 50:50 diet grew similarly at the 5% feeding rate but not when fed at 2.5%. Positive contribution of silage in the 50:50 diet fed at 5% is suggested By the facts that when fed at 2.5%, pellet alone was insufficient to promote growth equal to that on pellet fed at 5%, and silage alone produced more growth than non‐fed controls. Survival in cages averaged 95% for the fed treatments (90–100%), 89% for the non‐fed controls (88–90%). Data suggest that high fiber feeds such as corn silage can play a role in supporting the pond production of prawns and that the cage technique can be a useful tool in assessing prawn feeds in a pond en

ISSN:0735-0147    

DOI:10.1111/j.1749-7345.1982.tb00015.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY