Western King Prawn Research Articles

Growth and population characteristics of the Western King Prawn Penaeus latisulcatus (Kishinouye, 1896) from the southeastern Mediterranean off the Egyptian coast

Penaeus latisulcatus (Kishinouye, 1896) is considered one of the most economically important penaeid shrimp species in the Egyptian Red Sea. Recently, it appeared in the Egyptian Mediterranean catches. The present study is concerned with the estimation of growth, age and population characteristics of the non-indigenous P. latisulcatus collected between the months of July 2020 to June 2021 from the landing fishing center of Boughaz El-Maadiyah (Egyptian Mediterranean coast). A total of 2214 individuals were collected monthly. The results showed that the females to males ratio was 1:0.98. According to the Chi-square test, there was no statistically significant difference between the sexes (X2 = 0.181, df = 1, P > 0.05). The distribution of the length frequency showed that the females varied from 5.0 cm to 19.2 cm (TL) with a mean length of 11.73 ± 2.78 cm, while the males ranged from 5.3 cm to 17.1 cm (TL) with a mean length of 10.97 ± 2.06 cm. Positive allometry was detected for the total length-total weight relationship. The parameters of von Bertalanffy were L∞ = 20.56 cm, K = 0.99 yr−1 and to = −0.178 yr−1 for females, L∞ = 18.68 cm, K = 1.05 yr−1 and to = −0.172 yr−1 for males, and L∞ = 20.74 cm, K = 0.90 yr−1 and to = −0.196 yr−1 for the combined sexes. The expected age of females and males were 2.6 and 2.2 years, respectively. According to the parameters obtained, the current exploitation rate of the population of P. latisulcatus was estimated at Ecur. = 0.59. The results indicated that the population of P. latisulcatus is being highly exploited in Boughaz El-Maadiyah landing center (Egyptian Mediterranean coast). Hence, it is important to manage the P. latisulcatus shrimp resources in the studied area. Furthermore, similar studies are recommended for P. latisulcatus along the Egyptian Mediterranean coast to evaluate variations between populations in different fishing areas. Moreover, further studies are needed about the new aspects of the reproductive activity of this species as well as its aquaculture to estimate its growth rate experimentally.

Factors Affecting the Recovery of Invertebrate Stocks From the 2011 Western Australian Extreme Marine Heatwave

The extreme Western Australia 2011 marine heatwave had a lasting effect on the marine ecosystem and after seven years, only parts of the ecosystem have showed good signs of recovery. After the heatwave, scallop fisheries in the Abrolhos Is. and Shark Bay were closed for 3-5 years, while the Shark Bay crab fishery was closed for 18 months; these fisheries at the centre of the heatwave have shown some improvement due to better protection of spawning stock and improved environmental conditions. Also at the centre of the heatwave, Roe’s abalone suffered a catastrophic mortality and has not recovered as spawning stock remains very low. The Perth abalone stock which was outside the peak heatwave area had a major stock reduction but remained opened with reduced catches. The heatwave had a marked indirect effect on brown tiger prawns in Exmouth Gulf due to loss of seagrass habitat. The heatwave also resulted in a decline in western king prawn recruitment in Exmouth Gulf, to the north of heatwave centre, but an improved recruitment in the cooler waters of Shark Bay. Western rock lobsters near the heatwave peak also appear to have been indirectly affected and have not recovered. Factors influencing the recovery rate from the heatwave appeared to be: species near their upper temperature range and/or sensitive to warming temperatures; spatial overlap between the warming event and species distribution; whether spawning stock was affected to the point of recruitment impairment; life-cycle duration of invertebrate (or habitat) species affected; and management intervention. This study provides a framework for managing the consequences of heatwaves on fisheries by highlighting the value of early identification of the event and its effect on fisheries and having flexible harvest strategies for early management intervention. This is particularly important as long-term increases in water temperatures will increase the frequency of marine heatwave events and the fisheries stocks would have less time for recovery

Refining a Nordmøre-grid bycatch reduction device for the Spencer Gulf penaeid-trawl fishery.

Incremental refinements were made to a generic Nordmøre-grid to minimise bycatches of blue swimmer crabs Portunus armatus and giant cuttlefish Sepia apama, while maintaining catches of western king prawns Melicertus latisulcatus in the Spencer Gulf penaeid-trawl fishery. These refinements involved varying bar spaces, escape-exit areas and guiding-panel lengths, and were compared against a conventional trawl. Catches of teleosts and M. latisulcatus largely remained unaffected by the changes. Maximum reductions in P. armatus and S. apama bycatches (both ~90%) were achieved with a Nordmøre-grid comprising 38-mm bar spaces, 0.81- or 1.05-m2 escape exits and a 2.7-m guiding panel. Catching fewer P. armatus should reduce abrasion and crushing of M. latisulcatus in the codend and so increase the value of this targeted species. While noting some unresolved operational concerns, these results demonstrate the potential improvements in selectivity in this fishery using a Nordmøre-grid, primarily by mechanical separation.

The first complete mitochondrial genome of Melicertus from M. latisulcatus (Decapoda: Penaeidae)

The western king prawn, Melicertus latisulcatus, is a tropical species of ‘grooved shrimps’, which has long adrostral groove along almost the entire dorsal carapace in Penaeidae family. However, the taxonomic revision studies of Penaeidae have been one of the most controversial issues in recent years. In this study, we report the first complete mitochondrial genome of Melicertus from M. latisulcatus. The mitogenome has 15,971 base pairs (64.7% A + T content) and made up of total of 37 genes (13 protein coding, 22 transfer RNAs, and 2 ribosomal RNAs), and a control region. This study was the first available complete mitogenomes of Melicertus and will provide useful genetic information for future phylogenetic and taxonomic classification of Penaeidae.

Visual Stimuli for the Induction of Hunting Behavior in Cuttlefish Sepia pharaonis.

Cuttlefish exhibit typical hunting behavior, including elongating tentacles against specific prey such as prawn and mysid shrimp. Cuttlefish hunting behavior involves three different actions: attention, positioning, and seizure. Hunting behavior is innate and stereotypic behavior, and it is present in newly hatched juveniles. Factors associated with prey are known to induce this behavior, similar to the sign stimulus, whereby young herring chicks imitate pecking behavior against a red dot on their parent's bill. Although the hunting behavior of cuttlefish has been described and used as an indicator to test learning and memory, details of a stimulus that can elicit this behavior remain unknown. Here, we used a variety of visual stimuli presented on a computer screen to investigate the factors that induce hunting behavior of pharaoh cuttlefish, Sepia pharaonis. We found that the appearance of prey (western king prawn, Melicertus latisulcatus) and their movement at a vertical angle of 45° are specific factors that can initiate hunting behavior. We also showed that the height of prey can attract cuttlefish and initiate hunting. To the best of our knowledge, this is the first report of a stimulus that elicits stereotyped hunting behavior by coleoid cephalopods.

Molecular and biometric characterizations of the Western king prawn Melicertus latisulcatus (Kishinouye, 1896) in the Egyptian Red Sea.

Molecular and biometric characterizations of the Western king prawn Melicertus latisulcatus (Kishinouye, 1896) in the Egyptian Red Sea.

Improving fleet efficiency to maximise economic yield in a Western Australian prawn fishery

The Shark Bay trawl fishery is Western Australia's most valuable prawn fishery (worth AUD$25 million in 2014). The 18-vessel fleet targets western king prawns (Penaeus latisulcatus), brown tiger prawns (P. esculentus) and also retains saucer scallops (Ylistrum balloti) and blue swimmer crabs (Portunus armatus). Increased fuel prices, falling prawn prices and lower catches of other species, following extreme environmental events, have impacted fishery profits. A biomass dynamics model with an economic component indicated that total revenue levels start to decline when annual effort increases beyond ~ 200 fishing days per boat. Annual effort required to achieve MEY, when based solely on prawn fishing, is 115–150 days per boat after accounting for fixed and variable fishing costs and annual fishing efficiency increases of 1–2%. From 2007–2014, the adjusted effort was 188–192 days per boat. Fishing occurred between March and November during 7–8 fishing periods, separated by 5–8day (low catchability) moon closure periods. An empirical daily profit assessment (2007–2015), accounting for recruitment variation, daily prawn size compositions, monthly market prices for different prawn species and sizes, and daily fishing costs, showed vessels made profits on ~ 115–160 days and losses on ~ 15–55 days per year, when fishing occurred near the full moon. The fishery benefitted in 2013–2015 by starting later in the year and better targeting within-season effort. This management strategy within the effort-control framework, which improved profitability, maintained higher spawning stocks and reduced ecosystem fishing impacts, has wider application in prawn fishery management.

A biophysical model to assess the trade-off between larval recruitment and catch in southern Australia's largest prawn fishery

Data from stock assessment surveys, published research and climate sensors were linked to model the interaction between fishing, physical‐oceanographic processes and spatial patterns of larval settlement for western king prawn [Penaeus (Melicertus) latisulcatus]. This information was used to evaluate the trade‐off between larval recruitment and catch during fishing periods that demand high prices but coincide with spawning. Total rates of larval settlement were maximized when tidal currents and atmospheric physical‐forcing components were coupled with simulations of larval swimming behaviour under average gulf temperatures. Average gulf temperatures sustained longer larval durations and increased larval settlement rates by over 12% compared with warmer gulf conditions simulated under a scenario of global warming. Reproductive data coupled with outputs from the biophysical model identified consistent inter‐annual patterns in the areas contributing to larval settlement success. Areas located in the north‐east, and central‐west of the fishery, consistently contributed to over 40% of all larvae reaching a settlement in each year. Harvest sensitivity analyses indicated that changes in the spatial patterns of pre‐Christmas fishing could lead to improvements in overall rates of the larval settlement while maintaining or improving the levels of catch. Future studies to refine the model inputs relating to physical processes, larval behaviour and mortality rates for P. latisulcatus coupled with surveys of juvenile prawn abundance to ground truth the modelled predictions, would allow stock recruitment relationships to be more closely examined and inform adaptive management of the fishery in the future.

Reducing discards in a temperate prawn trawl fishery: a collaborative approach to bycatch research in South Australia

Abstract We present the outcomes of a collaborative research programme tasked with reducing bycatch, and thus discards in a temperate Australian prawn trawl fishery. Sea trials in the Gulf of St Vincent, South Australia, assessed the performance of a modified trawlnet that incorporated a rigid polyethylene grid and a T90-mesh codend. Compared with conventional designs, the modified net yielded marked reductions in bycatch (cumulatively >81% by weight), with pronounced decreases in sponge (92%), elasmobranchs (80%), teleost fish (71%), molluscs (61%), and crustaceans (78%). Using commercial logbook data, we estimate that the use of modified nets could reduce discards by ∼240 tons per year. This outcome was achieved with moderate declines in the catch rate (kg h−1) of the target species, Western King Prawn (mean ∼15%), of which almost all were small adults of low commercial value. Adoption of the modified net by industry was realized in March 2012, because it met environmental objectives (i.e. reducing bycatch and improving public perceptions of sustainability), reduced prawn damage, demonstrated commensurate financial returns, and engaged stakeholders throughout the development process. Overall, the project provides a useful example of bycatch research with demonstrable outcomes of improving the ecological and economic sustainability of prawn harvests.

Mitigating the bycatch of giant cuttlefish Sepia apama and blue swimmer crabs Portunus armatus in an Australian penaeid-trawl fishery

Trawlers in Spencer Gulf, Australia, target western king prawns Melicertus latisulcatus, with nearly all other species discarded; two of the latter have evoked significant, although quite different, concerns. The first is the giant cuttlefish Sepia apama, which has undergone a drastic decline in numbers in Spencer Gulf in recent years, and is listed as 'Near Threatened' by the International Union for the Conservation of Nature. S. apama are susceptible to trawling during their annual spawning migration through Spencer Gulf. The other bycatch problem involves large quantities of blue swimmer crabs Portunus armatus, which currently are separated inside the trawl using a large-meshed liner. Due to the additional handling required and the physical damage caused by the crabs' exoskeletons on the soft-bodied M. latisulcatus and Sepia spp., P. armatus would ideally be able to escape of their own accord during towing. This study examined the utility of mechanical-separating bycatch reduction devices (BRDs) for reducing unwanted bycatches of Sepia spp. and P. armatus. We compared (against conventional codends) the smallest and largest practical sizes of Nordmore-grids (the latter to maximise sorting area), with correspondingly large and low grid angles. The large Nordmore-grid significantly reduced Sepia spp., P. armatus and total bycatch (by 33-50%), but had no effect on catches of M. latisulcatus. Whilst additional research is required, a modified Nordmore-grid should help to resolve the bycatch of P. armatus and S. apama in this fishery, with minimal commercial impacts.

The search for a filter-feeding alternative for integrated shrimp aquacultures– a preliminary study with the polychaete Sabella spallanzanii for water quality improvement

The search for a filter-feeding alternative for integrated shrimp aquacultures– a preliminary study with the polychaete Sabella spallanzanii for water quality improvement

The effects of temperature on larval size in the western king prawn, Penaeus (Melicertus) latisulcatus Kishinouye, from Spencer Gulf, South Australia: implications for fishery management

Temperature, salinity and food availability are generally considered to have the most influence on larval growth and survival in penaeid species. Larval size has previously been used as a measure of animal quality in a range of crustacean species. The aim of this project was to investigate the effects of temperature (17°C, 20°C, 22.5°C and 25°C) on stage-specific larval size in Penaeus latisulcatus collected from the Spencer Gulf, in South Australia. Five different measurements of larval size were assessed: body length, body width, antenna length, carapace length and abdomen length. Results showed that larval growth rate was dependant on temperature, with growth rate greater at higher temperatures. Despite this, larvae reared at 20°C reached the largest size, while those at the temperature extremes (17°C and 25°C) were smallest. When considering average annual temperature, the spawning time that would most likely maximise larval size in the Spencer Gulf is approximately December. This coincides with current management arrangements for the fishery that protect the spawning biomass at this time of year.

Integration of blue mussel (Mytilus edulis Linnaeus, 1758) with western king prawn (Penaeus latisulcatus Kishinouye, 1896) in a closed recirculating aquaculture system under laboratory conditions

Integrated farming methods, where filter feeders are used to absorb suspended particles have been used for treating nutrients and particulate wastes from prawn culture system. This study investigated the effects of integrating varying stocking densities of blue mussels (Mytilus edulis) with western king prawns (Penaeus latisulcatus) on the water quality and animals growth rates under a closed recirculating aquaculture system. The experiment was conducted using fifteen indoor recirculating systems which tested four different mussel and prawn stocking ratios (replicates of three) with a control of having prawns only. The four mussel densities and prawn biomass ratios were 0.25, 0.50, 1.00 and 2.00. Mussels in the system removed significant (P<0.05) amounts of the total nitrogen, total suspended solids and total bacteria but did not alter the ammonia nitrogen. The dissolved inorganic nitrogen, orthophosphate and total phosphorus concentrations increased with the increasing mussel stocking densities. Integrating mussels and prawns did not affect the prawn growth and survival but mussel growth rate was positively correlated with the increasing stocking mussel densities. Nitrogen and phosphate contents in dried mussel meat in integrated environment were lower in those were integrated with prawns than in the initial mussel stocks. The study showed that mussels can grow and survive in the closed integrated culture system and effectively remove total suspended solids, total nitrogen and the total bacteria from the cultured environment. The research recommends mussel stocking density to prawn biomass ratio of 2.00 for the closed integrated recirculating aquaculture system.

Effects of feeding rates on the growth, water quality and nutrient budget of western king prawn (Penaeus latisulcatusKishinouye) reared in recirculating aquaculture systems

Feed rate is one of the important variables considered for the improvement in production of prawns. The effects of four feeding rates on growth, water quality and the nutrient budget of Penaeus latisulcatus were investigated for 98 days. The specific growth rate (SGR) at 3.0% feed rate was significantly higher than at all higher feed rates, and there was no significant difference in SGR between 4.5%, 6% and 7.5%. Total ammonia nitrogen concentrations in all treatments remained low in the safe range for prawn culture. Dissolved inorganic nitrogen and nitrate nitrogen were significantly higher (P < 0.05) in prawn tanks received feed rates of 6.0% and 7.5%. Total phosphorus and the soluble reactive phosphorus linearly increased with the progression of the trial and feeding rates. Nutrient conversion rates were significantly higher (P < 0.05) in prawns receiving the feeding rate of 3.0% than feeding rates of 6.0% and 7.5%. The lowest food conversion ratio was recorded at feeding rates of 3% and 4.5%. Nutrient budget showed that 6.01–15.99% nitrogen and 4.53–9.29% phosphorus of the nutrient inputs were retained in the prawn biomass. The results indicated that the growth and nutrient conversion rate may not increase with the increase above 3.0% of biomass per day.

Temperature dependent larval duration and survival of the western king prawn, Penaeus (Melicertus) latisulcatus Kishinouye, from Spencer Gulf, South Australia

The effects of temperature on growth, development and survival of penaeid prawn larvae ultimately influence recruitment to fisheries. This is of particular importance for temperate prawn fisheries in South Australia that target the semi-tropical western king prawn Penaeus (Melicertus) latisulcatus. P. latisulcatus resides at its lower temperature limit in South Australia, where it is restricted to the warmer waters of the gulf and embayment systems. Duration and survival were determined for three larval stages of P. latisulcatus reared at constant temperatures: 17, 20, 22.5 and 25°C. Data were subsequently used to construct a larval development model to generate predictions of larval duration for varying hatch dates when water temperature was within spawning range (November–May) at two different spawning grounds within Spencer Gulf (north vs. south). Results demonstrated that water temperature had affected larval development, duration and subsequently total survival. A power relationship was found between temperature and larval duration such that lower temperatures exerted the greatest influence. Under a constant laboratory temperature regime, total larval development ranged from 12.7days (at 24.4°C) to 31.3days (at 17.1°C). Stage-specific duration was generally greatest for protozoea, while developmental variability among individuals was greatest at later stages and at higher temperatures. Daily survival (~98% day−1) was similar between 17°C (total end survival: 36%) and 25°C (total end survival: 74%) treatments, suggesting the upper thermal tolerance limit is greater than mean water temperature maxima in temperate Spencer Gulf. A seasonal larval duration model predicted total duration to be shorter at the beginning of the spawning season (26.8days: 9 November) due to increasing daily water temperatures, compared to later in the season (35.4days: 29 May). Furthermore, larval duration was predicted to be significantly shorter in warmer northern (minimum 12.7days) compared to southern (minimum 17.2days) spawning grounds. These results improve the understanding of the factors that affect larval dispersal, settlement and recruitment of P. latisulcatus.

Integration of western king prawn ( Penaeus latisulcatus Kishinouye, 1896) and green seaweed ( Ulva lactuca Linnaeus, 1753) in a closed recirculating aquaculture system

Integrating recirculating aquaculture systems with seaweeds is one of the strategies that can minimise wastes and risk of disease outbreaks. This study investigated the effect of integrating green seaweed ( Ulva lactuca) with western king prawns ( Penaeus latisulcatus) at varying stocking densities on the water quality, nutrient conversion rates and nutrient budget under closed recirculating culture system. The experiment was conducted using fifteen indoor tank recirculating systems and tested four different stocking ratios of prawns and seaweed with a control having prawns only. The four stocking ratios of seaweed and prawn biomass were 2, 4, 8 and 16 per tank. The mean concentrations of total ammonia nitrogen (TAN), NO 3 −–N and PO 4 3−–P in the prawn and seaweed tanks were significantly lower (P < 0.05) in the integrated culture systems than in the prawn monoculture. U. lactuca was highly efficient in removing the inorganic nutrients from the culture systems with TAN removal rate of 59–81% and PO 4 3−–P removal rate of 50–55%. Integrating seaweed with prawns did not significantly alter the specific growth rate (SGR) and survival rate of the prawns (P > 0.05). Ratio of C:P in seaweed tissues decreased with increasing seaweed stocking densities while C:N ratio showed an adverse trend. The nutrient conversion rate into total biomass (prawns plus seaweed) in the integrated systems was significantly higher at the highest seaweed stocking density (2.00 kg m − 2 ). Nutrient budget revealed that seaweed retained about 6.5–29.7% nitrogen and 1.6–13.5% phosphorus inputs while values for prawns were 28.0–31.9% and 13.5–14.6%, respectively. Seaweed also removed dissolved inorganic nitrogen effectively in the closed recirculating aquaculture system.

Application of Electrochemical Treatment for the effluent from Marine Recirculating Aquaculture Systems

Abstract An actual wastewater from a western king prawn (Penaeus latisulcatus) culturing tanks located in Zhoushan (Eastern coast of China) was investigated through electrochemical process. Under an electrical field, ammonia and nitrite were indirectly oxidized by electro-generating HOCl, whereas organic compounds were directly oxidized at the anode surface. To achieve simultaneous removal of total ammonia nitrogen (TAN), nitrite (NO2-N) and Chemical oxygen demand (COD), the current density had to be controlled over 23.4 A/m2. Concurrently, finely suspended particles (SS) were effectively separated from wastewater by electroflotation, while the current density was below 25 A/m2. The retention time had insignificant effect on TAN, NO2-N and SS removal. However, the removal efficiency of COD was highly related with the retention time. Experimental results indicated the optimum operating conditions: 25 A/m2 of current density, and 40 minutes of retention time. Under these conditions, the energy consumption was 1.75 kWh/m3 wastewater.

Effect of Customized Probiotics on the Physiological and Immunological Responses of Juvenile Western King Prawns (Penaeus latisulcatus Kishinouye, 1896) Challenged with Vibrio harveyi

Juvenile western king prawn P. latisulcatus were fed 105 colony-forming units (CFU)/mL of two probiotics Pseudomonas synxantha and P. aeruginosa for 28 days. P. latisulcatus were then challenged with V. harveyi at 0 (control), 103, 105, and 107 CFU/mL. During the seven days of challenge, disease resistance of the probiotic-fed prawns was compared with that of prawns not fed probiotics. The immunological responses of the prawns did not improve during the challenge period in terms of total haemocyte count, hyalinocyte, semi-ganulocyte, granulocyte, clotting time, bacteraemia, and intestinal bacterial load. Overall, when prawns were challenged with V. harveyi, the LT50 values got shorter as V. harveyi concentration increased. LT50 values of prawns fed probiotics were significantly longer (P < 0.05) than those not fed probiotics. At a V. harveyi concentration of 103 CFU/mL, the 100% survival of the prawns fed probiotics was three times more likely than those of the prawns not fed probiotics.

Evaluation of Sargassum sp. as a nutrient-sink in an integrated seaweed-prawn (ISP) culture system

Effluent water from intensive prawn aquaculture systems typically has a high concentration of dissolved nutrients such as nitrogen and phosphorus. A study was conducted for 42 days to investigate the nutrient flow in a system where brown seaweed ( Sargassum sp. ) was integrated into western king prawn ( Penaeus latisulcatus) culture. Three treatments namely, western king prawn monoculture (5.48 ± 0.29 g), Sargassum sp. monoculture and seaweed/prawn integrated culture were tested for nutrient flow among feed, water and species cultured. The results showed that by integrating seaweed into prawn culture, the concentrations of total ammonium nitrogen (TAN), nitrite–nitrogen (NO 2 −) and nitrate–nitrogen (NO 3 −), dissolved inorganic nitrogen (DIN), total nitrogen (TN), phosphate (PO 4 3−) and total phosphorus (TP) were significantly lower (p < 0.05) in the integrated culture system than in the prawn monoculture (p < 0.05) and remained within non-toxic limits for the duration of the study. In addition, the integration of Sargassum sp. with western king prawn culture did not significantly alter the nitrogen and phosphorus conversion rates from feed into prawns (approximately 17.69–18.99 and 13.79–14.47%, respectively). The specific growth rate (SGR) and survival rate of the prawns in integrated treatment did not significantly differ (p > 0.05) from the prawn monoculture. The mean biomass of Sargassum sp. in integrated culture increased at the rate of 3.16 ± 0.74% g day −1 after 7 days of the study, which was significantly higher than in the monoculture system (5.70 ± 0.82% g day −1). The results suggest that integrating Sargassum sp. into western king prawn culture can benefit prawn farming by assisting in the maintenance of optimum water quality and thereby, reducing environmental impacts on surrounding areas.

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.