Experiments to assess the suitability of nine species of prawns for intensive cultivation

This paper describes experiments in which nine species of prawns were compared for their suitability for intensive culture in closed systems. The species tested were: Macrobrachium rosenbergii, Penaeus aztecus, P. indicus, P. japonicus, P. monodon, P. occidentalis, P. orientalis, P. schmitti and P. setiferus. Tanks with a bottom area of 0.6 m² and water depth 20 cm were stocked with juvenile prawns (0.2–0.5 g mean live-weight) of each species at two stocking densities, equivalent to 25 and 166 prawns/m². Water conditions were maintained at 28±2°C and 28–30‰ (M. rosenbergii was reared in fresh water), and growth and survival were monitored during 16 weeks.Fastest growth was recorded for P. monodon and P. orientalis, which reached mean live-weights of 25.43 g and 22.80 g respectively at the low stocking density and 12.95 g and 14.63 g at the high stocking density. Best survival was recorded for P. monodon, which was considerably better than any of the other species. It was concluded that P. monodon and P. orientalis merit further consideration as candidates for intensive culture.     

Effects of stocking density on the nutrient budget and growth of the western king prawn (Penaeus latisulcatus Kishinouye) in a recirculating aquaculture system

Intensification in the commercial culture of prawns can have a significant impact on the water quality and hence on the survival, growth and the surrounding environment. The present study aims to evaluate the effects of stocking density on the water quality and performance of the western king prawns (Penaeus latisulcatus) and the nutrient budget of the culture environment. Four stocking densities of 4, 8, 16 and 32 prawns m^?2 were tested in 12 recirculating systems. Prawn weight and specific growth rate increased with decreasing stocking density, while the survival rate showed the reverse trend. The mean total ammonia nitrogen, nitrate nitrogen, total phosphorus and soluble reactive phosphorus were significantly higher (P<0.05) at the higher stocking density. The nutrient budget revealed that the prawns could assimilate only 9.34–20.13% nitrogen and 4.97–11.25% phosphorus of the total nutrient inputs. The drained water at harvest was the major sink of phosphorus and nitrogen at stocking densities of 4, 8 and 16, which accounted for 45.59–64.82% and 44.28–65.62% of the total inputs, respectively, while a significant proportion of nitrogen sunk into the sediment at 32 prawns m^?2. The study suggested that the stocking densities of western king prawns can be up to 16 prawns m^?2 in the recirculating water environment.     

Culture of Macrobrachium rosenbergii (De Man 1879) in experimental cages in a freshwater eutrophic lake at different stocking densities

Macrobrachium rosenbergii (de Man 1879) juveniles (0.4 g) were cultured in experimental cages (L × W × H: 2.5 × 1 × 1 m) in Laguna de Bay, the largest lake in the Philippines. The following stocking densities at four replicates each were used: 15, 30, 60 and 90 prawns m⁻² of cage bottom. The mean sizes at harvest after 5 months of culture ranged from 14.3 g for the highest stocking density to 26.3 g for the lowest. The mean size at harvest, daily growth rate and size class distribution were significantly influenced by stocking density, with those at the lowest stocking density showing significantly better growth and overall proportion of larger prawns. Heterogeneous individual growth (HIG) was fairly evident in all treatments. The percentage of blue‐clawed males was not influenced by treatment but the mean weight was significantly higher in the lower stocking densities. Both the percentage and mean weight of berried females were significantly higher in the lowest stocking density. Survival was the highest in the lower stocking densities (55.3%, 54.0%, 52.7% and 36.9% for 15, 30, 60 and 90 prawns m⁻² respectively). Feed conversion ratio (FCR) improved with decreasing stocking density, ranging from 2.1 to 3. As expected, yield per cropping increased with stocking density and ranged from 450 to 1089 g m⁻² yr⁻¹ of actual cage area. Production values obtained in the cage cultured M. rosenbergii were comparable to or even higher than those reported from pond culture, given that the stocking densities used in this study were generally higher than in ponds. The results show that the farming of M. rosenbergii in cages in lakes is a viable alternative to pond culture and has the potential of improve aquaculture production in lakeshore fish farming communities.     

杂交青虾“太湖1号”苗种在池塘养殖中的适宜放养密度

以饲料系数、养殖产量、成虾规格、体长与体质量特定生长率作为判据,水质状况作为参考,以杂交青虾"太湖1号"为实验对象,在放养密度为60、105、150、195、240尾/m35个梯度下进行为期100 d的养殖试验,研究杂交青虾"太湖1号"苗种在池塘养殖中的适宜放养密度。结果显示,150尾/m3组的饲料系数显著低于195尾/m3和240尾/m3组(P<0.05),而养殖产量及成虾规格显著高于其它各组(P<0.05)。在高于150尾/m3的高密度组中,虽然产量也显著高于低密度组(P<0.05),但成虾规格较小。养殖期间各养殖水体的水质均能满足养殖虾的生长需求;高温季节除了高密度组的亚硝态氮盐指标稍有升高以外,水体pH、DO、NH4+-N等指标基本保持一致。将放养密度分别与饲料系数、增重率、体长与体质量特定生长率等指标之间进行二次回归曲线方程拟合,计算出杂交青虾"太湖1号"的适宜放养密度为117～150尾/m3。     

Production Characteristics of All‐male and Mixed‐sex Giant River Prawns,Macrobrachium rosenbergii,Grown in Earthen Ponds in Kentucky and Mississippi USA

Production and population characteristics of monosex male (all‐male) giant river prawns, Macrobrachium rosenbergii, were compared with a normal (mixed‐sex) population in separate studies in Mississippi and Kentucky (USA) under low and high density stocking conditions, respectively. In Study 1 (Mississippi), juvenile prawns were stocked into eight 0.05–0.06 ha ponds at 24,700/ha. The mean stocking weight of all‐male was 0.34 g and mixed‐sex was 0.39 g. Prawns were fed 23% crude protein “range cubes” and harvested after 120 d for the all‐male prawns and 112 d for mixed‐sex prawns. In Study 2 (Kentucky), juvenile prawns from each group were stocked into six 0.04 ha ponds at 60,000 juveniles per hectare. The mean stocking weight for all‐male was 0.38 g and for mixed‐sex juveniles was 0.34 g. Prawns were fed a commercial sinking pellet (33% protein) once daily at a standardized rate and harvested after 105 d. In both locations survival of mixed‐sex prawns and all‐male prawns was not significantly different and the final average weight of all‐male prawns was significantly greater than the average weight of mixed‐sex prawns. For the study in Kentucky, total production was not significantly different between treatments, whereas in Mississippi total production in the all‐male ponds was significantly higher than in the mixed‐sex ponds. For both studies, the production size index of all‐male prawns was significantly greater than that of mixed‐sex prawns. In terms of population structure, in all‐male ponds there was a significant increase in orange claw (OC) males compared with the mixed‐sex ponds both as a percent of sex and a percent of total population. The increase in OC numbers in all‐male populations may be due to a lack of females to stimulate the transition of males to the final, sexually mature, blue claw stage. As target weights increase from 20, 30, and 40 g, the all‐male populations were increasingly superior in terms of production (kg/ha) of those target sizes. The economic benefit of all‐male over mixed‐sex populations will be principally based on an examination of tradeoffs that primarily consider the cost difference of juveniles relative to the price differences for different final harvest weights.     

A study of the optimum stocking density and feed rate for school prawns Metapenaeus macleayi (Haswell) in some Australian brackish water farming ponds

A stocking density experiment was conducted in 18 experimental enclosures within a single 0.11 ha pond. As stocking density increased in the range 6.1–21.2 prawns/m², school prawn growth declined while survival rate was unaffected and total harvest (final biomass) increased. A simple economic analysis indicated that the optimum stocking density for juvenile school prawns was 19.1 prawns/m². In a similar experiment the effects of feeding school prawns with a pelleted diet at a range of supplementary feed rates (0–12.5% of prawn biomass/day) were investigated. The optimum feed rate in terms of growth was approximately 5% of biomass/day. However the optimum feed rate, in terms of the economic return index used, varied depending on the estimated cost of the diet.     

Effects and Interactions of Stocking Density and Added Substrate on Production and Population Structure of Freshwater Prawns Macrobrachiurn rosenbergii

The effects and interactions of added artificial substrate with different stocking densities of prawns were evaluated. Juvenile prawns (0.2 ± 0.1 g) were stocked into 12 0.04-ha ponds at 60,000ha and 120,000/ha with and without substrate. Added substrate consisted of horizontal plastic mesh and strips of "oyster netting" sutlicient to increase available surface area 80%. There were no statistically significant ( P > 0.05) interactions between stocking density and presence of added substrate, allowing these main effects to be compared separately. Increasing stocking density produced a significant increase ( P < 0.01) in total production but a significant decrease ( P < 0.01) in average prawn size and production ( P < 0.05) of market size prawns (>20 g, -27%; > 30 g, -56%). Added substrate also produced a significant increase ( P < 0.05) in total production (18%). However, average prawn size was not decreased and production of marketable shrimp was increased (>20 g, 25%; >30 g, 19%). Feed conversion ratios were significantly decreased (P < 0.01) by the presence of substrate. Increased stocking density significantly increased ( P < 0.05) the percentage of males which were small males (SM) and decreased ( P < 0.01) the percentage of orange claw males (OC), but had no impact ( P > 0.05) on numbers of reproductive (RF) and virgin (VF) female morphotypes. Increased stocking density also produced a significant decrease ( P < 0.05) in average size of OC, RF, and VF morphotypes while the addition of substrate had no statistically significant impact (P > 0.05) on the number or size of different morphotypes. The mathematical relationship between available surface area and average prawn size should be determined to produce recommended inclusion rates for added substrate based on desired levels of total production, stocking rates, and optimum market sizes.     

MALAYSIAN PRAWN CULTURE IN BRACKISH WATER PONDS IN LOUISIANA

Beginning on May 13, 1980, prawns were cultured at the Rockefeller Wildlife Refuge for 140 days from postlarvae and fed. Production in ponds receiving Ralston Purina Experimental Marine Ration #25 averaged 408 kg/ha, 619 kg/ha and 510 kg/ha for the respective replicated stocking densities of 2.5/m², 4.9/m² and 7.4/m². Average feed conversion factors were 1.0, 1.0 and 1.5. Average prawn weights at harvest decreased with increased stocking density and were 21 g, 17 g and 12 g, respectively. Production per pond ranged from 390 kg/ha to 832 kg/ha. An average of 77% of prawns stocked at 2.5/m² exceeded 115 mm TL whereas the stocking densities of 4.9/m² and 7.4/m² yielded only 32% and 31% over 115 mm. Extra postlarvae remaining after the stocking requirements for the feeding study were met permitting additional tests. Stocking rates selected for these additional studies were 1.2/m², 2.5/m² and 3.7/m². Prawns in these ponds received no supplemental feed and yielded harvests of 124 kg/ha, 224 kg/ha and 292 kg/ha, respectively. These treatments, the first two of which were not replicated, resulted in production similar to that of an earlier study of prawn production on natural forage in brackish ponds at this facility. Average prawn sizes at harvest were 18 g, 15 g and 12 g, and were inversely related to stocking densities.     

The breeding and growth of Penaeus merguiensis de Man in laboratory recirculation systems

Penaeus merguiensis was cultured through three generations in laboratory recirculation systems. Populations of 24–76 prawns produced, on average, 2–15 batches of 44 000 eggs per month throughout a 16-month period. Survival to metamorphosis was over 50% and post-larvae reached a size (0.15 g live weight) suitable for stocking in “grow-out” tanks 50–60 days after being spawned. In the subsequent 16 weeks prawns reached 5–7 g live weight with 24–58% survival.     

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.     

EFFECT OF POPULATION STRUCTURE AND DENSITY AT STOCKING ON PRODUCTION AND COMMERCIAL FEASIBILITY OF PRAWN (Macrobrachium rosenbergii) FARMING IN TEMPERATE CLIMATES1

During 1978–1980, 18 rearing trials were conducted in 0.25 ha ponds to examine the effects of various stocking strategies on production and economic potential. The strategies tested consisted of stocking: post-larvae only; a mixed population of postlarvae plus juveniles; small juveniles only, at densities ranging from 2.15–8.61 prawns/m². Prawns were fed Purina Marine Ration 25 once daily and seine-sampled at 4-week intervals throughout the 144–168 day rearing periods. Clear relationships between population structure of the stocked prawns and density versus crop yields and estimated revenues were demonstrated. The stocking of postlarvae resulted in lower production levels and less valuable prawns as compared to stocking a mixture of postlarvae + juveniles or juveniles only populations. Also, survival was more variable (range 59.3–84.5%) and lower (mean 69.6%) when postlarvae were stocked. Greater crop yields were achieved at higher densities, however, mean size and unit value of the crop decreased as density increased. Feed conversions were low and averaged 1.4 (range 0.8–2.2) for all trials combined. Preliminary economic feasibility analyses of the various stocking strategies were performed for situations where ponds and associated facilities were already available. The analyses suggested that positive net revenues were possible if a mixed population of postlarvae and juveniles or juveniles only were stocked at about 6.5/m² and seed costs were ∑30/1,000 and the crop was marketed as a combination of large whole.     

Response of estuarine consumer communities following the stocking of a juvenile penaeid (Penaeus plebejus) over two consecutive years

Research programmes that monitor and evaluate the impact of stocking activities are essential to quantify effects of stocking and provide information for adaptive management of future releases. The consumer communities in two estuaries stocked with 5.8 million post‐larvae eastern king prawn Penaeus plebejus (Hess) were monitored, both before and after stocking, and relative to two similar reference estuaries. Following stocking, there was evidence of increases in the abundances of prawns within stocked estuaries. Communities in all four estuaries showed significant levels of variation over time as well as among the systems themselves. Changes in overall diversity were similarly observed. The presence or absence of vegetation and other seasonal effects were found to explain most of the observed variation in the community assemblage, while prawn stocking appeared to have a little detectable influence. While this study points to minimal impacts of prawn stocking on the consumer community at the densities used, research into potential shifts in resource use by competitors and the growth and survival of prawns is required to fully understand post‐release changes in stocked systems.     

靖海湾和五垒岛湾放流增殖中国对虾的回游与分布

用烧结法标志中国对虾，在靖海湾和五垒岛湾进行增殖放流，研究其回游与分布规律。重捕资料表明，６月中旬幼对虾对湾内河口浅水区生活随体长增长，逐步向深水扩散；８月上，中旬主群陆续游向湾外，按地形走向向西南回游，部分向东或东南；１０月份回游对湾外水域的对虾有向东，东北或东南回游的现象。     

Polyculture of Macrobrachium rosenbergii and Notemigonus crysoleucas

A polyculture study was conducted in southwest Louisiana comparing production of Malaysian prawns, Macrobrachium rosenbergii , in monoculture and polyculture with Golden shiners, Notemigonus crysoleucas .
This test revealed stocking of shiners at 24.7/m² with prawns at 4.4/m² resulted in increased total pond production over monoculture of prawns at 4.4/m² with equal prawn yields in both systems and little increase in labor. Feeding rates were based on prawn biomass. Food conversion ratios ranged from 0.5 to 1.0 in polyculture and 0.9 to 1.1 in monoculture when total production was considered. Prawn production averaged 640 kg/ha in polyculture and 629 kg/ha in monoculture. Mean size of prawns was 19 g in polyculture and 20 g in monoculture. The polyculture of shiners with prawns added an average of 307 kg/ha of the bait fish to pond production.
Shiners did not compete seriously with prawns when stocked at these rates. This practice could result in added revenues to producers culturing these species together.     

Breeding depressions in culture ponds for Malaysian prawns

Breeding depressions constructed by male Malaysian prawns, Macrobrachium rosenbergii, were observed in earthen culture ponds in South Carolina. Depressions ranged from circular to elliptical in shape and the maximum size recorded was 94 × 53 cm and 15 cm deep. Number and size of depressions appeared to be closely related to the size and density of the adult male prawns in the ponds. Night-time observations indicated that sexually ripe females oriented in and around the depressions. Although construction of breeding depressions appears to be common under pond culture conditions, such depressions are not necessary for successful reproduction.     

Effects of Stocking Size and Density of Tilapia on Macrobrachium rosenbergii in Polyculture

Studies were conducted to determine the effect of stocking size and density of prawns in polyculture.
In one experiment, postlarval prawns (av. wt. 0.02 g) were stocked in six 0.02 ha earthen ponds at 35,00O/ha. Two ponds were stocked with tilapia fry (av. wt. 0.14 g) and two were stocked with tilapia fingerlings (av. wt. 30.1 g), each at 10,000/ha. Two control ponds had no tilapia. Tilipia stocking size had no effect on prawn growth. Mean weight of prawns after 70 days of culture ranged from a low of 4.5 g when cultured with tilapia fingerlings to a high of 6.6 when cultured in monoculture. Prawn survival was adversely affected by tilapia fry. Average prawn survival in tilapia fry ponds was 65% compared to 75% and 91%, respectively, in tilapia fingerling and monoculture ponds.
In a second experiment, postlarval prawns were stocked in nine 0.02 ha earthen ponds at 40,000/ ha. Six ponds were stocked with 30 g tilapia fingerlings, three at 5,000/ha and three at 15,000/ha. Three control ponds received prawns only. After 100 days of culture, prawn weight ranged from an average of 15.9 g in monoculture ponds to 11.5 g in polyculture ponds. Survival was highest (93.8%) in low density polyculture ponds. Survival was lowest (85.6%) in prawn monoculture ponds. Tilapia reproduction had a negative impact on shrimp production.     

Effect of Shelters,Densities, and Weight Groups on Survival,Growth and Limb Loss in the Freshwater Prawn,Macrobrachium nobilii (Henderson and Matthai, 1910)

Abstract

Three weight groups of juvenile prawn, M. nobilii, were raised at three stocking densities (22,38, and 77 prawns/m²) under three substrate conditions (sand, pebbles, and pebbles with shelter in the form of PVC pipe). Stocking density had a significant (P < 0.001) influence on the survival and growth of the prawn. A higher incidence of limb autotomy was recorded at the higher stocking density. Provision of pebbles and PVC pipe increased the survival, and mean growth rates, and reduced the percentage of limb loss.     

Production of Nile Tilapia Oreochromis niloticus and Freshwater Prawn Macrobrachium rosenbergii Stocked at Different Densities in Polyculture Systems in Brazil

Abstract.— The effect of stocking prawns Macrobrachium rosenbergii at increasing densities in ponds with Nile tilapia Oreochromis niloticus reared at low density was evaluated. Twelve 0.01-ha earthen ponds were stocked with 1 tilapia/m² and 0, 2, 4, or 6 postlarvae prawn/m². Three replicates were randomly assigned to each prawn density. Postlarval prawns were stocked a week prior to tilapia juveniles and both were harvested 175 d after the beginning of the experiment. Tilapia final average weight, survival, production, and food conversion rates did not differ significantly among treatments ( P > 0.05); the averages were 531 g, 67%. 3,673 kg/ha, and 1.91, respectively. Prawn survival rates did not differ for the three stocking densities (mean 90%). However, final weight and production were significantly different ( P < 0.05) as follows: 34.0, 23.0, and 14.7 g and 639, 909, and 818 kg/ha, respectively for 2. 4, and 6 prawns/m² densities. Stocking densities up to 6 prawn/m² did not affect tilapia production and required neither additional feeding nor significant changes in management. The polyculture system allowed an increase in total production with the same amount of supplied feed, thus improving the system sustainability.     

Effects of Harvesting Methods on Population Structure,Growth and Yield of Freshwater Prawn,Macrobrachium rosenbergii,Cultured at Two Densities

Effects of harvesting methods (cull and batch) on population structure, growth, and yield of freshwater prawn, Macrobrachiurn rosenbergii, cultured at two densities (5/m2 and 10/m2) were evaluated. Females (67.4%) were more abundant than males (32.6%), but there was no effect of harvesting methods and stocking rates on sex ratio (P > 0.05). Mean survival rates ranged from 78.3 to 92.6%, being highest at a stocking density of 10/m2 and cull-harvested (P < 0.05), but were not different (P > 0.05) among three other treatments. After 196 days of culture, mean weights ranged from 25.3 to 29.9 g and were not significantly different from each other (P > 0.05). Mean weight of males was not hi her than that of f females (P > 0.05), except in one treatment (5/m² , batch harvest) where males were heavier (P < 0.05). Maximum specific growth rate (SGR) was recorded for prawns cultured at a density of 5/m² and cull-harvested (0.66%/day), followed by prawns at 10/m² and cull-harvested (0.58%/day). Minimum SGR was found for prawns cultured at 10/m² density and balch-harvested (0.43%/day). Maximum yield (2366 kg/ha and 2099 kg/ha) was recorded at the higher density (P < 0.05). Harvesting method had no effect on yield at any density (P > 0.05).