Survival Of Prawns Research Articles

Effects of probiotics (Pseudomonas synxanthaandPseudomonas aeruginosa) on the growth, survival and immune parameters of juvenile western king prawns (Penaeus latisulcatusKishinouye, 1896)

The effects of two selected probiotics (Pseudomonas synxantha and Pseudomonas aeruginosa) on the specific growth rate (SGR), survival and immune parameters of juvenile western king prawns (Penaeus latisulcatus) were examined for 84 days. Pseudomonas synxantha and P. aeruginosa were either applied into the rearing medium or supplemented in the formulated feed at a concentration of 105 colony forming unit (CFU) mL−1 for each probiotic. The results showed that applications of the probiotics resulted in no significant difference (P>0.05) in the SGR and survival of the prawns, but significantly decreased the food conversion ratios (P<0.05) compared with the control where no probiotics were applied. The supplement of the probiotics with the formulated feed enhanced the probiotic numbers in the intestines of the prawns and low bacteria numbers in the haemolymph. The prawns were significantly (P<0.05) healthier, as indicated by the immune response obtained when both probiotics were given in combination compared with when individual probiotics were used. When applied singly, P. aeruginosa resulted in a higher health status of the prawns compared with P. synxantha. Overall, equal combinations (105 CFU mL−1) and volumes of P. synxantha and P. aeruginosa used as a supplement in the formulated feed resulted in an improvement in the health of the juvenile western king prawns.

Effects of addition of tilapia Oreochromis niloticus and substrates for periphyton developments on pond ecology and production in C/N-controlled freshwater prawn Macrobrachium rosenbergii farming systems

The present research investigated the effect of addition of tilapia and substrates for periphyton development on pond ecology, production and economic performances in C/N controlled freshwater prawn farming system. The absence and presence (0 and 0.5 individual m − 2 ) of tilapia were investigated in 40 m 2 ponds stocked with 3 prawn juveniles (individual weight 5 g) m − 2 with or without added substrates for periphyton development. A locally formulated and prepared feed containing 30% crude protein (C/N ratio10) was applied daily, initially at 10% of the prawn stocked biomass and was gradually reduced to 3% of prawn biomass. Tapioca starch was used as carbohydrate source for increasing the C/N ratio from 10 (as in feed) to 20 and was applied to the water column separately from the feed. Addition of periphyton substrates significantly reduced the inorganic N-species (NH 3–N, NO 2–N and NO 3–N) in the water column. It decreased the abundance of plankton in the overlying water and increased the abundance of benthic macroinvertebrates. The abundance of periphytic algae and periphyton biomass (dry matter, ash free dry matter and chlorophyll a) were significantly higher in tilapia free ponds compared to tilapia added ponds. Both substrates and tilapia had significant effects on feed conversion ratio (FCR) of freshwater prawn: substrates decreased FCR by 14% while tilapia addition increased it by 16%. The addition of substrates did not influence prawn and tilapia size at harvest but improved the survival of prawn from 54 to 77%. Substrates contributed 44% and 19% higher net yield of prawn and tilapia, respectively whereas tilapia addition decreased the net yield of prawn by 14%. The economic analysis showed that addition of tilapia and periphyton substrates jointly improved the benefit–cost ratio. Addition of tilapia and periphyton substrates in C/N controlled system benefited the freshwater prawn culture practices through (1) reducing toxic inorganic nitrogenous compounds in water (2) enhancing the utilization of natural foods (3) improving survival, production and economic benefit.

Does mercury interact with the inhibitory effect of dichlorvos on Palaemon serratus (Crustacea: Decapoda) cholinesterase?

Mercury is one of the most hazardous metals that may contaminate estuarine ecosystems and induce toxic effects on wildlife organisms. It has been suggested that impairment of cholinesterase (ChE) activity may be involved in the resulting mercury toxicity. Following Palaemon serratus exposure to mercury chloride (HgCl 2), no effect on ChE activity was observed whatever the concentration used (to 37.5 µM) or the time of exposure (to 7 days). By contrast, following 24 h exposure to dichlorvos, an organophosphate insecticide with a well-characterised anti-ChE action, decrease of ChE activity was observed until 30 to 40% basal activity, which seems to be the minimum activity required for prawn survival. In addition, HgCl 2 does not affect dichlorvos toxicity and treatments with a mixture of both compounds can be interpreted as the sum of the two independent toxicities. Therefore, mercury and insecticide toxicities are independent and ChE activity from P. serratus eyes seems to be a reliable and sensitive biomarker for organophosphate insecticides even when organisms are simultaneously exposed to mercury.

Impact of Substrate Physical Characteristics on Grow Out of Freshwater Prawn, Macrobrachium rosenbergii, in Ponds and Pond Microcosm Tanks

Abstract Two independent trials were conducted to evaluate the effects of different physical characteristics of substrate materials on growth and survival of freshwater prawn. In Trial 1, juvenile prawns (0.4 ± 0.2 g) were stocked at 123 prawns/m2 of tank bottom into twenty‐one 18,000‐L fiberglass tanks managed as pond microcosms. Six substrate materials were chosen to allow comparisons of surface area, mesh size, color, and texture. A control treatment received no added substrate. There were three replicate tanks per treatment. Substrates were positioned vertically at a rate sufficient to increase the bottom surface area by 100%. Prawns were fed a 32% protein sinking diet according to a feed chart. After 110 d, there was no significant difference (P &gt; 0.05) in survival among treatments, averaging 72.6% overall. Prawns in the control treatment (no substrate) had significantly lower (P ≤ 0.05) average weights (9.5 g), lower production (1342 kg/ha), and higher feed conversion ratio (FCR; 2.5) than those in substrate treatments, which were not significantly different (P &gt; 0.05) and averaged 13.4 g, 2404 kg/ha, and 1.3, respectively. For Trial 2, the least expensive substrate material from Trial 1 (lightweight polyethylene bird netting) was compared with the substrate most commonly used in commercial production (heavyweight orange polyethylene safety fencing) under practical pond conditions. Juvenile prawns (0.8 ± 0.3 g) were stocked at 61,600/ha into six 0.04‐ha earthen ponds. Each was randomly assigned one of the two substrate materials, and there were three replications per treatment. After 101 d, there were no significant differences (P &gt; 0.05) between treatments in terms of survival (91%), average weight (34 g), total production (2150 kg/ha), or FCR (3.1). In these studies, physical characteristics of the substrate materials had little impact. The lightweight netting represents a 68% cost savings compared to the currently recommended substrate material.

Potential of mixed culture of freshwater prawn (Macrobrachium rosenbergii) and self-recruiting small species mola (Amblypharyngodon mola) in rotational rice–fish/prawn culture systems in Bangladesh

The effects of different stocking densities of freshwater prawn (Macrobrachium rosenbergii) on its growth and production in relation to the presence of small self-recruiting species mola (Amblypharyngodon mola) were investigated in modified rice fields after rice harvest at Mymensingh, Bangladesh. Keeping the stocking density of mola fixed at 20 000 ha−1 in each treatment, four densities of freshwater prawn (treatments) were maintained: 10 000, 15 000, 20 000 and 25 000 ha−1 respectively. The rice plots were limed (CaCO3) and fertilized with urea, triple super phosphate and cowdung regularly. The prawns were fed daily with commercial pellets. Water quality parameters such as temperature, dissolved oxygen, transparency, pH, total alkalinity, inorganic nitrogen (nitrate, nitrite and total ammonia), chlorophyll a and orthophosphate were determined fortnightly. Numerical analysis of plankton communities was performed monthly. All water quality parameters were found to be within the suitable range for freshwater prawn culture, except high temperature, in the peak summer months. There was a homogenous abundance of plankton communities in all treatments throughout the experimental period. Mola started to breed in the second month of the original stocking with partial harvesting after the second month and continued until the final harvest. The total production of mola ranged between 124 and 152 kg ha−1 during the 4-month culture period. The average prawn survival ranged from 49% to 57% without any significant difference among treatments. Freshwater prawn production ranged from 294 to 596 kg ha−1 with significantly higher production in the treatment where 20 000 ha−1 freshwater prawn were stocked. This treatment also resulted in a higher net profit margin (74%), indicating that stocking at a combination of 20 000 ha−1 freshwater prawn and 20 000 ha−1 mola could be the optimum proposition for prawn–mola culture in modified rain-fed rice fields after rice cultivation.

Effects of stocking density on production and economics of Nile tilapia (Oreochromis niloticus) and freshwater prawn (Macrobrachium rosenbergii) polyculture in periphyton-based systems

The present research investigated the effect of stocking density on pond (75 m2, depth 1.2 m) production of Nile tilapia (Oreochromis niloticus) and freshwater prawn (Macrobrachium rosenbergii) stocked at a fixed 3:1 tilapia:prawn ratio. Three stocking densities were tried in triplicate: 20 000 ha?1 (treatment TP-20), 30 000 ha?1 (TP-30) and 40 000 ha?1 (TP-40). The ponds were provided with bamboo as substrate for periphyton development. Bamboo poles (mean diameter 5.5 cm and 5.0 poles m?2) were posted vertically into pond bottoms, resulting in 60% additional substrate area in each pond. On average, 43 genera of algae and 17 genera of zooplankton were identified from pond water, whereas 42 genera of algae and six genera of microfauna were attached to bamboo substrates. No differences were observed between treatments in the ash-free dry matter (AFDM), chlorophyll a and phaeophytin a content of periphyton (P>0.05). Survival of tilapia and prawn and individual weight gain of tilapia were lower (P

Effects of Staining and Streamer Tags on Survival and Growth of Juvenile School Prawns, Metapenaeus macleayi, Under Laboratory Conditions

Juvenile school prawns from two size classes (carapace length 11-20mm and 21- 30mm) were marked with a stain (fast green FCF solution) or tagged with steamer tags under laboratory conditions to test the hypothesis that tagging or marking affects the survival and/or growth of prawns. The stain accumulated in all parts of the prawn, but after 14 days it was visible only in the gills. All surviving tagged prawns at the end of each experiment had their streamer tags intact with tag information still visible. Tagging and staining significantly reduced survival, but there was no significant difference in mortality (40-50%) between these two techniques. Mortality was at its highest for all treatments in the first week of the experiments, reflecting the stress associated with handling the prawn and applying the tag or stain. Mortality was not size- or sex-dependent and marking or tagging did not appear to affect growth. While the low survival rates are of concern, this laboratory study suggests that streamer tags are the most suitable method for use in mark-recapture population studies for juvenile school prawns.

Efficacy of fermented prawn shell waste as a feed ingredient for Indian white prawn, Fenneropenaeus indicus

Prawn shell waste collected from shrimp-processing plants in Cochin, India, was subjected to fermentation using 20 chitinoclastic and proteolytic/non-proteolytic bacterial strains. The products generated were analysed for protein, lipid, total sugars, N-acetyl glucosamine, free amino acids and ash. Shrimp diets were prepared using these 20 fermented products and a control diet using raw prawn shell waste. Feeding experiment was conducted with postlarvae (PL21) of Indian white prawn, Fenneropenaeus indicus for a period of 21 days. Biogrowth parameters such as mean weight gain, feed conversion ratio, specific growth rate and protein efficiency ratio were estimated and the animals were challenged with white spot virus orally via diet. Enhanced growth could be observed in prawns fed F134 and F124, incorporated with the fermentation products generated using Bacillus spp., C134 and C124 respectively. The percentage survival of prawns after 7 days of challenge was found to be highest for groups fed diet F111 incorporated with fermentation product generated using Bacillus sp. These products of bacterial fermentation hold promise as growth enhancers and immunostimulants in aquaculture.

Effect of thyroxine immersion on larval survival, growth and postlarvae production of freshwater prawn, Macrobrachium rosenbergii (de Man)

Aquaculture ResearchVolume 37, Issue 13 p. 1378-1380 Effect of thyroxine immersion on larval survival, growth and postlarvae production of freshwater prawn, Macrobrachium rosenbergii (de Man) Paymon Roustaian, Paymon Roustaian Department of Fisheries and Aquaculture, Faculty of Agrotechnology and Food Science, Kolej Universiti Sains dan Teknologi Malaysia (KUSTEM), Kuala Terengganu, Malaysia Department of Fisheries, Faculty of Marine Resources, Khoramshahr University of Marine Science and Technology (KUMST), Khoramshahr, Khozestan, IranSearch for more papers by this authorLim Ai Gaik, Lim Ai Gaik Department of Fisheries and Aquaculture, Faculty of Agrotechnology and Food Science, Kolej Universiti Sains dan Teknologi Malaysia (KUSTEM), Kuala Terengganu, MalaysiaSearch for more papers by this author Paymon Roustaian, Paymon Roustaian Department of Fisheries and Aquaculture, Faculty of Agrotechnology and Food Science, Kolej Universiti Sains dan Teknologi Malaysia (KUSTEM), Kuala Terengganu, Malaysia Department of Fisheries, Faculty of Marine Resources, Khoramshahr University of Marine Science and Technology (KUMST), Khoramshahr, Khozestan, IranSearch for more papers by this authorLim Ai Gaik, Lim Ai Gaik Department of Fisheries and Aquaculture, Faculty of Agrotechnology and Food Science, Kolej Universiti Sains dan Teknologi Malaysia (KUSTEM), Kuala Terengganu, MalaysiaSearch for more papers by this author First published: 25 August 2006 https://doi.org/10.1111/j.1365-2109.2006.01576.xCitations: 5 Correspondence: P Roustaian, Department of Biology, University of New Brunswick, PO Box 5050, Saint John, New Brunswick, Canada E2L 4L5. E-mail: proustai@unbsj.ca Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume37, Issue13September 2006Pages 1378-1380 RelatedInformation

Effect of sudden salinity change on Penaeus latisulcatus Kishinouye osmoregulation, ionoregulation and condition in inland saline water and potassium-fortified inland saline water

Two trials were conducted to determine the effect of sudden decrease in salinity of raw and potassium-fortified inland saline water on western king prawn Penaeus latisulcatus osmoregulation, ionoregulation and condition. Prawns were subjected to salinity decrease over 1 h from 32 to 25 ppt in the first trial and from 27 to 20 ppt in the second trial in three water types: inland saline water with potassium fortified to 100% and 80% of the marine water concentration (IS100, IS80), and raw inland saline water (ISW). In the first trial condition and ingestion rate were monitored over 19 days following salinity change. In the second trial condition, haemolymph osmo- and iono-regulation were recorded over 48 h following salinity change. In the first trial, 100% mortality was observed in ISW by day 13, with final survival 94% in IS80 and 100% in IS100. Tail muscle moisture content increased significantly (P < 0.05) over time in both trials and in all water types, suggesting loss of energy reserves. In the second trial, serum osmolality, sodium concentration and osmoregulatory capacity decreased following salinity change, stabilising by 24 h in IS100 and IS80 but continuing to decrease till 48 h in ISW, suggesting partial breakdown of osmoregulatory function in the potassium-deficient medium. Prawns were stronger regulators of divalent than monovalent cations. These trials demonstrate that potassium-deficient inland saline water requires fortification with potassium to allow prawn survival and efficient osmoregulation.

The Effect of Biomass Density, Salinity, and Substrate on Transport Survival of Juvenile Freshwater Prawns Macrobrachium rosenbergii in Continuously Oxygenated, Vented Containers

AbstractDuring the stocking of grow‐out ponds, juvenile prawns are usually transported from regional nurseries by truck in vented tanks. Hauling stress and associated delayed mortality have been implicated as potential causes of low pond survival. An experiment was conducted to evaluate the effects of biomass density, substrate, and salinity on water quality and transport survival of juvenile freshwater prawns Macrobrachium rosenbergii. The trial was designed as a 3 × 2 × 2 factorial and evaluated three biomass densities (10, 20, and 30 g/L), the presence or absence of added substrate (plastic mesh to provide a 200% increase in surface area), and the presence or absence of added salt (0‰ or 6‰). Model transport tanks were 15‐L, open styrofoam containers aerated with pure oxygen and compressed air. Water quality analyses were performed prior to stocking. After 24 h, water quality analyses were again conducted and all prawns were removed, designated as alive or dead, weighed, and counted. After 24 h of simulated transport, three‐way analysis of variance indicated no significant interactions (P &gt; 0.05) between the main effects of density, substrate, or salinity for prawn survival or water quality. When the main effects were analyzed separately, survival was significantly influenced by density. Survival was significantly lower (P &lt; 0.05) in the high‐density treatment (30 g/L: 89% survival) than in the medium‐ (20‐g/L) and low‐density (10‐g/L) treatments, which were not significantly different (P &gt; 0.05) and averaged 95% survival overall. Total ammonia nitrogen and un‐ionized ammonia nitrogen concentrations significantly increased (P &lt; 0.05) as biomass density increased. The addition of salt to the transport water did not significantly affect survival (P &gt; 0.05) but did result in a significant decrease (P &lt; 0.05) in both pH and un‐ionized ammonia nitrogen. Added substrate had no significant (P &gt; 0.05) impact on any measured variable. These data indicate that good survival can be achieved at a biomass density of 20 g/L and that increased salinity appears to reduce the buildup of toxic metabolites. The addition of substrate to the transport tank appears to provide no benefit.

Optimization of stocking density of freshwater prawn Macrobrachium rosenbergii (de Man) in carp polyculture in Bangladesh

A study was conducted to optimize stocking density of freshwater prawn, Macrobrachium rosenbergii, in carp polyculture for 3 months in 10 experimental ponds of 80 m2. Five stocking densities of prawn, 2500, 5000, 7500, 10 000 and 12 500 ha−1, were assigned to treatments T1, T2, T3, T4 and T5 respectively. The densities of catla, Catla catla, rohu, Labeo rohita and silver carp, Hypophthalmicthys molitrix, were 2500, 5000, and 2500 ha−1, respectively, in each treatment. Each treatment had two replicate ponds. The mean initial weights of prawn, catla, rohu and silver carp were 1.1±0.02, 8.28±0.1, 25.2±1.1 and 36.32±1.2 g respectively. A pelleted diet containing 30% protein was prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses, and was fed twice daily at a rate of 5% of fish biomass. Water quality parameters were measured fortnightly and the ranges of temperature, pH and dissolved oxygen were 27.5–1.3°C, 6.9–8.6 and 4.5–8.6 mg L−1 respectively. Feed conversion ratios ranged from 2.05 to 2.20 among the treatments. Per cent survival (%) of prawns ranged from 72% to 78%, while it varied from 80% to 93%, 90% to 95% and 90% to 92% for catla, rohu and silver carp respectively. The results showed that there were no significant differences among the weight gains of prawn and carp in different treatments. However, the overall total production of prawn and fish together was significantly (P<0.05) higher in T3 and T4 compared with other treatments. The total production for 3 months ranged between 2618 and 2916 kg ha−1. The production of prawn was significantly higher (361.3 kg ha−1) in T5 with a highest stocking density of 12 500 prawn ha−1. Although there was no significant difference (P>0.05) between the total production of prawn and fish together in T3 and T4, the highest net profit (Tk. 69 006 ha−1) was obtained in T4. Therefore, from the result of the study it may be concluded that a stocking ratio of 4:1:2:1 of prawn:catla:rohu:silver carp at a total density of 20 000 ha−1 may be recommended for prawn–carp polyculture in ponds.

The growth and survival of western king prawns, Penaeus latisulcatus Kishinouye, in potassium-fortified inland saline water

Western king prawns, Penaeus latisulcatus are a candidate species for culture in inland saline water. Western king prawn survival, growth, condition, osmo- and iono-regulation was studied when reared in potassium-fortified inland saline water for 202 days. PL40 prawns were stocked into three media in 250 L tanks: inland saline water with potassium fortified to 80% (IS80) of the marine water concentration, 100% (IS100) of the marine water concentration and marine water (MW). By the conclusion of the trial, survival was 53% in IS80, 64% in IS100 and 68% in MW. Mean prawn weight, total length, carapace length, condition factor and moult interval were significantly higher ( P < 0.05) in MW than in IS100 and IS80. Specific growth rate of prawns in MW was significantly higher ( P < 0.05) than in IS80. There were no significant differences ( P > 0.05) in osmoregulatory capacity of prawns between various media. Serum Na +, K +, Ca 2+and S concentrations were influenced by their concentration in the medium. Ca 2+ was the only major cation hyper-regulated and tended to be accumulated, while Mg 2+ was maintained at a much lower concentration in the serum than in the medium. Moisture contents in hepatopancreas, tail muscle and exoskeleton and organosomatic indices improved from IS80 to IS100 to MW. The lower growth rates and condition factors of prawns reared in potassium-fortified inland saline water suggests the presence of limiting factors other than potassium concentration. Western king prawns are stronger regulators of divalent cations than monovalent cations and the extra energy required to regulate ions in inland saline water may have been the major cause of lower growth rates.

The influence of temperatures ranging from 25 to 36 °C on developmental rates, morphometrics and survival of freshwater prawn ( Macrobrachium rosenbergii) embryos

An in vivo study was conducted to assess effect of incubation temperature on embryonic development and hatching period of freshwater prawn ( Macrobrachium rosenbergii) . Brooders spawned on a single day were distributed among four temperature treatments, each with six replicates, and acclimated at a rate of 1 °C/day above and below ambient water temperature (30 °C) to reach test temperatures (25, 29, 33 and 36 °C) and maintained in separate rearing conditions until hatch. Sampling of developing embryos was done at 24-h intervals until mortality/hatching and observed under a light microscope. Major half axis, minor half axis, area and perimeter were measured at 48-h intervals. Embryonic development rates increased with increasing temperatures [ y (time from early morula hatch; h) = 40.075 x (temperature; °C) + 348.75; R 2 = 0.993). A rapid increase in major half axis, larval length, and faster hatching correlated with higher temperatures. Hence this study revealed that incubation temperature significantly influences the time to and duration of hatching and survival of M. rosenbergii eggs.

The potential of mixed culture of genetically improved farmed tilapia (Oreochromis niloticus) and freshwater giant prawn (Macrobrachium rosenbergii) in periphyton-based systems

The production performance of genetically improved farmed tilapia (GIFT, Oreochromis niloticus) and freshwater prawn (Macrobrachium rosenbergii) in periphyton-based systems were studied in farmers' ponds at Mymensingh, Bangladesh. Fifteen ponds (200-300 m2 area and 1.0-1.5 m in depth) were used to compare five stocking ratios in triplicate: 100% GIFT, 75% GIFT plus 25% prawn, 50% GIFT plus 50% prawn, 25% GIFT plus 75% prawn and 100% prawn. Ponds were stocked at a total density of 20 000 GIFT and/or prawn ha -1. Bamboo poles (mean diameter 6.2 cm and 5.5 pole m-2) were posted in pond bottoms vertically as periphyton substrate. Periphyton biomass in terms of dry matter (DM), ash-free DM and chlorophyll a were significantly higher in ponds stocked with prawn alone than in ponds with different combinations of GIFT and prawn. Survival of GIFT was significantly lower in ponds stocked with 100% GIFT (monoculture) whereas, that of prawn was significantly higher in its monoculture ponds indicating detrimental effects of GIFT on prawn's survival. Individual weight gains for both species were significantly higher in polyculture than in monoculture. The highest total fish and prawn yield (1623 kg GIFT and 30 kg prawn ha-1) over 125-140 days culture period was recorded in ponds with 75% GIFT and 25% prawn followed by 100% GIFT alone (1549 kg ha-1), 50% GIFT plus 50% prawn (1114 kg GIFT and 68 kg prawn ha-1), 25% GIFT plus 75% prawn (574 kg GIFT and 129 kg prawn ha-1) and 100% prawn alone (157 kg ha-1). This combination also gave the highest economic return. Therefore, a stocking ratio of 75% GIFT plus 25% prawn at a total density of 20 000 ha-1 appeared to be the best stocking ratio in terms of fish production as well as economics for a periphyton-based polyculture system

The Effect of Biomass Density, Temperature, and Substrate on Transport Survival of Market-Size Freshwater Prawn, Macrobrachium rosenbergii

After harvest, adult prawn are often transported for sales to live markets, such as ethnic Asian outlets, in major urban centers. Poor survival during transportation has hindered development and expansion of these markets. Methodologies to increase survival during transport could contribute to industry viability. Three independent trials were conducted. In the first trial, three biomass densities (25, 50 and 100 g/L) were evaluated in 100-L, open plastic containers aerated with pure oxygen and compressed air. Water quality analyses were performed prior to stocking. After 24 hours in the model transport containers, water quality analysis was conducted and all prawn were removed, determined to be alive or dead, and each group weighed and counted. There was no significant difference (P > 0.05) for prawn survival (overall mean 98%) among the three densities. Concentrations of dissolved oxygen and nitrite were not effected by hauling density (P < 0.05). Total ammonia-nitrogen and un-ionized ammonia-nitrogen concentrations increased (P < 0.05) as biomass densities increased, though values remained within what are considered tolerable ranges. In the second trial, the effect of added substrate and temperature on transport survival was evaluated with prawns stocked at the high density (100 g/L). Two water temperatures (21°C and 26°C) with and without substrate were evaluated in a 2 × 2 factorial with three replicate, 100-L model transport containers per treatment combination (12 containers total). Factorial analysis indicated no significant statistical interaction (P > 0.05) between the presence of substrate and water temperature on any measured variable. The main effects of substrate and temperature were then analyzed separately. The presence or absence of substrate had no significant impact (P > 0.05) on prawn survival. However, temperature had a highly significantly impact (P < 0.01) on survival; prawn survival at 21°C averaged 97% compared to 24% at 26°C. The third trial was a commercial verification trial in which 500 kg of live prawn were transported to New York from Kentucky. These data indicate prawn can be successfully transported at 100 g/L for 24 hours when temperatures are maintained near 21°C. Adding substrate to the transport tank appears to provide no benefit.

Growth, survival, haemolymph osmolality and organosomatic indices of the western king prawn (Penaeus latisulcatus Kishinouye, 1896) reared at different salinities

The growth, survival, haemolymph osmolality and organosomatic indices of the western king prawn, Penaeus latisulcatus, (2.95±0.26 g mean initial weight), were measured when reared at 10, 22, 34 and 46 ppt salinity for 60 days. Mean final weight, total length and specific growth rate (SGR) of the prawns were highest at 34 ppt. Rearing at different salinities did not alter moult increments and intermoult periods of the prawns. One hundred percent mortalities were observed at 10 ppt.Survival was highest at 22 ppt and food conversion ratios were significantly lowest (P<0.0.5) in prawns cultured at 22 and 34 ppt. Haemolymph osmolality increased with the increase in medium salinity and physiological age of the prawns. Isosmotic points calculated from regression between haemolymph and medium osmolality were 28.87, 29.46 and 31.73 ppt at 0, 20 and 60 days of culture, when body weights were 2.95±0.26, 4.02±0.47, 5.79±0.64 g respectively. After 60 days of culturing, hepatopancreatic moisture levels increased with the increase in salinity, whereas tail moisture levels remained unchanged. Wet and dry hepatosomatic indices were highest at 22 ppt. Wet tail muscle index was highest at 34 ppt, whereas dry tail muscle index did not change by any salinity levels. The results suggest that the optimum salinity range for rearing western king prawns ranges from 22 to 34 ppt and 10 ppt was unsuitable for culture.

Acute Toxicity of Copper to Juvenile Freshwater Prawns, Macrobrachium rosenbergii

Copper sulfate is an algicide that is commonly used for phytoplankton and filamentous algae control and has been used as a therapeutant in aquaculture. The objectives of this study were to determine the acute toxicity of copper sulfate and the safe level for use in freshwater prawn, Macrobrachium rosenbergii, production ponds in a high calcium and alkalinity environment. Six concentrations of copper sulfate (0, 0.2, 0.4, 0.6, 0.8, 1.0 mg/L) were tested in 8-L glass aquaria for 48 hours with three replicate aquaria per treatment. Concentrations of calcium hardness and alkalinity were set at 100 mg/L using calcium chloride and sodium bicarbonate, respectively. After 48 hours, survival of the control treatment (0% CuSO4) averaged 97%, which was significantly higher (P< 0.05) than that of all other treatments. The survival in the 0.2 mg/L and 0.4 mg/L (70% and 73%, respectively) concentrations of CuSO4 were significantly greater (P< 0.05) than higher dose treatments; but were not significantly different from each other (P> 0.05). Treatments containing 0.6, 0.8, and 1.0-mg/L copper sulfate demonstrated a dramatic decrease in prawn survival, which averaged 30, 7, and 0%, respectively. Regression analysis of the data predicted 48-hour LC50 for copper sulfate tobe0.46 mg/L. Since recommended application rates for use of copper sulfate as an algicide are 1.0 mg/L or more for water with alkalinities of 100 mg/L, copper sulfate treatments are not recommended for prawn production ponds.

Effects of stocking different fractions of size graded juvenile prawns on production and population structure during a temperature-limited growout period

Size grading of juvenile prawns prior to pond stocking is used to disrupt negative social interactions. Animals graded off the upper end of the size range can outperform ungraded animals by 20–50%. However, reports differ on the performance of the lower grade fraction. Some studies indicate that lower grade prawns can out perform ungraded populations within a 120–140-day growing season while other studies indicate that >140 growing days are required. The objective of this study was to compare the growth of this lower grade fraction with the upper grade fraction and an ungraded fraction of the same population within a temperature-constrained growing season of 100–120 days. Prawn juveniles that had been nursed 60 days were separated into three groups. Approximately 50% of the population was maintained ungraded with the full range of size variation. The other 50% was separated into two fractions (large=upper grade; small=lower grade) using a #13 bar grader (0.5-cm spacing). Ponds were randomly assigned to receive one of the three treatments (ungraded controls, upper grade, and lower grade) with average stocking weights of 0.5±0.3, 0.8±0.4, and 0.2±0.1 g ( x̄±S.D.), respectively. There were three replicate 0.04-ha ponds per treatment. All ponds were stocked at 59,280 ha −1. Artificial substrate was added to ponds at a rate to increase available surface area by 50%. After 104 days, there was no significant difference ( P>0.05) in survival of prawns from the three fractions (overall average 88%). Total production, marketable production (>20, >30 g) and average individual weight was significantly greater ( P<0.05) in prawns from the upper grade fraction. At harvest, there was no significant difference ( P>0.05) in total production or average individual weight of prawns stocked from the ungraded or lower graded fractions. Impacts of grading procedures on population structures were much more pronounced in females than in males with upper graded animals having a significantly higher ( P≤0.05) percentage of sexually mature reproductive females. Compared to ungraded juveniles, projected net returns were lower for lower graded prawns, higher for upper graded, and higher for combined lower and upper under all model farm scenarios. In summary, stocking of the upper graded fraction increased total production, average weights, and marketable production. There was no difference in lower graded and ungraded animal production variables.

Impact of silver barb (Barbades gonionotus Bleeker) on growth and survival of prawn (Macrobrachium rosenbergii) in polyculture system.

Impact of silver barb (Barbades gonionotus Bleeker) on growth and survival of prawn (Macrobrachium rosenbergii) in polyculture system.