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Astaxanthin is a ketocarotenoid that is the primary pigment in shrimp and has powerful biological effects. This molecule comprises a 40-carbon chain with multiple double bonds at the end that connects to ketone and hydroxyl groups. The terminal hydroxyl groups can react with fatty acids and form monoester and diester of astaxanthin. Shrimp waste is an inexpensive source of this compound, whose extraction and purification can improve the economy of fishery production and processing in addition to solving the problem of shrimp waste disposal. The efficiency of astaxanthin extraction from Penaeus semisulcatus and Penaeus merguensis wastes was compared for the first time in the present study, employing the fermentation process with two strains of Lactobacillus acidophilus and Lactobacillus plantarum bacteria. The extraction conditions and effects of various treatments on astaxanthin yield were then adjusted using a Box-Benken design with three parameters: fermentation temperature (30–40 °C), fermentation time (12–72 h), and specifically by modifying the waste particle size (40–60 mesh). Following purification of the pigment, H-NMR and FT-IR spectroscopies, as well as Rf values, were clearly utilized to identify the astaxanthin present in the waste. The findings demonstrated that P. semisulcatus shrimp waste had considerably greater extraction yield with both bacterial strains than P. merguiensis shrimp (p<0.05). Also, L. plantarum bacteria had a higher ability to create better fermentation conditions and, as a result, higher extraction of astaxanthin from both shrimp species. Optimum conditions for this bacterium include a fermentation temperature of 35°C, a time of 72 h, and a particle size of 80 mesh. The Rf value for mono (0.59) and diester (0.76) of astaxanthin obtained were in accordance with international standards. FTIR analysis determined the recognizable peaks of mono and diester of astaxanthin, including hydroxyl functional groups and the vibrational mode related to its ester at the end of the polyene chain of astaxanthin. Also, an examination of H-NMR data showed the presence of indicative protons related to astaxanthin and fatty acids attached to it in the chemical shift regions of the spectra of extracted astaxanthin esters. [ABSTRACT FROM AUTHOR]

Reproductive dynamics of commercially important penaeid prawn Penaeus merguiensis was investigated in the coastal waters of Maharashtra during 2002-2003 by collecting data from inshore nearshore and offshore, waters. The size at maturity was 123 mm for males and 133 mm for females. The species spawned throughout the year with two spawning peaks, major one during March-May and minor during October-December and spawning area of the species is offshore waters >40 m depth. Ova diameter study showed tendency to shed all their eggs at one instance, but the progression of modal sizes of mature females demonstrated that females with spawning periodicity of 26±5.5 days could spawn about 12 times during their life span. The sex ratio showed that mainly large sized mature females migrate towards offshore deeper waters. Fecundity was exponentially related to length by F= 0.000000528*TL5.2086. The population fecundity index in nearshore and offshore areas indicated two peaks with major spawning activity during March-April and minor during August-September. The egg production by the surviving population in the sea, gave major peak during April-May and a minor during November. The occurrence of juveniles in the catch was bimodal and their mean size declined twice in inshore, nearshore and offshore waters which pointed to two recruitment pulses in March and November in inshore waters and in March and December in nearshore and offshore waters. The percentage of juveniles was the highest in March which suggested that post-monsoon spawning in November was the most effective. The ratio of juveniles and the egg production gave annual survival rate of 0.03%. The monthly survival showed bimodal trend with peak in April (0.07%) and November (0.03%), which suggested that spawning during November-December and May-June was responsible for the two cohorts, the post-monsoon and pre-monsoon, among which the former was more successful. [ABSTRACT FROM AUTHOR]

در فصل صید سال 1398، اطلاعات صید، اطلاعات جوی و دریایی با هدف بررسی اثر عوامل محیطی بر میزان صید بر واحد تلاش صیادی (CPUE) میگوی موزی (Penaeus merguiensis) و سرتیز (Metapanaeus affinis) در صیدگاه‌های بندرعباس، قشم و بندر کلاهی به وسیله آزمون‌های رج‌بندی، آزمون جایگشتی و محاسبات رگرسیونی جمع آوری شد.طی 49 مرتبه تورکشی، 1932 کیلوگرم میگو شامل 1379 کیلوگرم میگوی موزی با میانگین 56/12 (با حدود اطمینان 95 درصد 68/9 تا 45/15) کیلوگرم بر ساعت و 553 کیلوگرم میگوی سرتیز با میانگین 18/5 (با حدود اطمینان 95 درصد 69/3 تا 68/6) کیلوگرم بر ساعت صید گردید. طبق نمودار رج‌بندی، صید بر واحد تلاش صیادی میگوی موزی با عمق، میزان بارندگی و دمای سطح آب ارتباط مستقیم و معنادار و با سرعت وزش باد، ابرناکی، رطوبت، شوری و ارتفاع موج ارتباط کمی دارد. میزان صید به ازای واحد تلاش صیادی میگوی سرتیز با شوری و دمای سطح آب ارتباط مستقیم و با ارتفاع موج و رطوبت ارتباط معکوس و با عمق، میزان بارندگی، سرعت وزش باد و ابرناکی ارتباطی نداشت؛ اما در نتایج آزمون جایگشتی، این روابط معنی‌دار نبود. طبق مدل دوجمله‌ای منفی در روش رگرسیون، متغیرهای متغیرهای سرعت شناور و میزان شوری (01/0P

β-glucans are produced by many organisms and could be used as supplementary feed to enhance immunity and growth in some aquatic animals. This study aimed to compare the effectiveness of β-glucans derived from two marine diatoms (Chaetoceros muelleri and Thalassiosira weissflogii) as growth promoters and immunity enhancers in banana shrimp (Penaeus merguiensis). Shrimp were divided into 3 groups: the control group was fed without β-glucan; the second and the third group were fed with 2 g kg−1 of β-glucan derived from C. muelleri and T. weissflogii , respectively. Shrimp were fed over a 30-day period to determine growth performance (final weight, weight gain, average daily gain (ADG), and feed conversion ratio (FCR)) at day 15 and day 30, respectively. The immune parameters determined were total hemocyte count (THC), phenoloxidase activity (PO) and immune gene expression. Survival rates were measured after 14 days of the feeding trial and Vibrio parahaemolyticus infection (6, 24, 48 h post infection). There was no significant difference (P > 0.05) for growth stimulation of shrimps between the two types of β-glucans (C. muelleri or T. weissflogii). Notably, shrimps fed with β-glucans had a higher final weight, weight gain, and ADG (P < 0.05) than shrimps fed with the control diet, while FCR of shrimps fed with both β-glucans was lower when compared to the control diet. Immune parameters, THC, PO, and gene expression of anti-lipopolysaccharide factor (ALF) and crustin were significantly higher (P < 0.05) in shrimps fed with β-glucans, especially with β-glucans from C. muelleri than the control group both before and after V. parahaemolyticus infection. Expression of penaeidin 3 and peroxiredoxin genes was significantly higher in shrimps fed with β-glucans after bacterial infection. Histopathology of hepatopancreas revealed an increase in blasenzellen hepatopancreatic epithelial cells (B cells) after 14 days of feeding which remained higher following infection with V. parahaemolyticus. The survival rate of shrimps fed with the diet containing β-glucan derived from either C. muelleri (82.2%) or T. weissflogii (77.8%) after V. parahaemolyticus infection was significantly higher than for the control group (51.1%) (P < 0.05). In conclusion, we propose that feeding banana shrimps with β-glucans derived from marine diatoms either C. muelleri or T. weissflogii at a 2 g kg−1 diet can significantly improve their growth performance and immunity. • β-glucans from diatom either C. muelleri or T. weissflogii had no toxicity and could be use as supplement for shrimp. • β-glucans derived from marine diatoms (C. muelleri and T. weissflogii) can improve banana shrimp growth and immunity. • β-1,3/1,6-glucan from C. muelleri is superior to β-1,3-glucan from T. weissflogii to promote shrimp growth and immunity. [ABSTRACT FROM AUTHOR]

A study was carried out to determine the maturation period, quality and quantity of sperms production in Banana shrimp male broodstock, Penaeus merguiensis fed different natural diets. The three different natural diets namely; squid, fish and shrimp flesh used in this study were obtained from known sources and fed to the tested shrimp in triplicate groups. Based on the results obtained, squid seem to be the most effective natural diet as it enhances the sperms maturation within 20 days. Feeding fish and shrimp flesh as diets for the Banana shrimp broodstock resulted in the observation of maturation in 22 and 24 days, respectively. Similarly, squid diet also recorded the highest (p = 0.002; p < 0.05) sperms count (58.6 to 74.5) as compared to fish diet (44.0 to 61.3) or shrimp diet (28.0 to 42.8). Also, feeding squid diet resulted in a higher percentage of live sperms with ranged between 97.75% to 98.80%. On the other hand, broodstocks fed fish and squid flesh was observed with ranges of between 96% to 97.86% and 92.54% to 96.06%, respectively. It was therefore concluded that squid diet was most effective to improve sperm quality, quantity and maturation period in male broodstock of P. merguiensis. Further study should be carried on the reproductive performance of broodstock fed with squid as diets and it effect on the performances of post larvae obtained. [ABSTRACT FROM AUTHOR]

Study on ovarian maturation stages were carried out using external morphological assessment of ovarian colourations and histological assessment of Oocyte structure for broodstock selection purpose. Stage 1 to Stage 4 of female shrimps broodstock were sampled from Kuala Muda, Kedah, Malaysia. Four obvious colourations of ovary stages were identified which are: yellow (Stage 1), green yellowish (Stage 2), light greenish (Stage 3) and dark green (Stage 4) through the morphological assessment. The Gonadosomatic Index (GSI) showed significant increment as the gonad reach advance stages. Histological assessment of Stage 1 ovary identified perinucleolar oocyte (PO) with small size oocytes. Stage 2 ovary was identified with yolkless oocyte (YO), Stage 3 ovary was identified with late stage of yolky globules and Stage 4 ovary was identified with fully yolky globules. From the results achieved, it can be concluded that the ovarian colourations and GSI can be applied to identify the ovarian maturation stages, meanwhile, the histology assessment is the most precise method to determine the ovarian maturation stages in more details and accurate for each of the ovarian maturation stages. [ABSTRACT FROM AUTHOR]

The water quality supporting the growth of aquatic animals on the surface is usually better than that those accumulated at the seabed and more bottomless sea. Since water usually brings many materials along the path all the way to reaching its end, their quality varies in places and seasons as area it passes also influences the possessed quality. By employing Penaeus merguiensis larvae produced by the Jepara's Marine Center for Brackishwater-Aquaculture Development owned by Jepara's government, this study analyzes varying effects in three nominal salinities (28, 32, and 36 ppt) and types of diets (Diet A: 100% live feed; Diet B: 100% FRIPPAK; Diet C: a combination of Diet A and Diet C, 50 % each) and finds the optimum water quality parameters such as dissolved oxygen, pH, and temperature on the growth of the newly introduced Penaeus merguiensis larvae. The results show that salinity of 28 and 32 ppt with Diet A works well in supporting the growth from Zoea to Postlarvae-1: Zoea-1 at 28 ppt with Diet A; Zoea-2 at 32 ppt with Diet A; Zoea-3 at 32 ppt with Diet A; Mysis-1 at 28 ppt with Diet A; Mysis-2 at 28 ppt with Diet C; Mysis-3 at 28 ppt with Diet A; Postlarva-1 at 28 ppt with Diet A. All shrimp prefers temperature ranging from 31-32.4°C with dissolved oxygen of 4.9-5.74 ppm and pH 7.0-8.1. [ABSTRACT FROM AUTHOR]

Illegal tin mining or unconventional mining activities produce tailings. Tailings contain dangerous heavy metals one of which is Lead (Pb). The increasing concentration of Pb in the waters will also increase its concentration in the body of the biota, one of which is shrimp. The purpose of this study was to analyse the Pb content in gills, hepatopancreas and muscle in Penaeus merguiensis, analyse the Pb content in water and sediments, measure the ability of Penaeus merguiensis in accumulating Pb in water and sediments, and determine the safe limit for consumption. Shrimp, water and sediment samples were analysed using AAS. The results showed that the highest Pb concentration in Penaeus merguiensis was hepatopancreas> gill> meat, with an average range of 0,1897–0,4064 mg/kg, gills 0,2424-0,4770 mg/kg, and meat 0,1348-0,1636 mg/kg. The average Pb concentration in water ranged from 0,2624 to 0,5713 mg/L, while the sediment ranged from 0,2783 to 0,9760 mg/kg. The ability of Penaeus merguensis to accumulate Pb included in the low category. The value of daily intake is around 9,760-11,128 kg/week. Aktivitas penambangan timah illegal atau tambang inkonvensional menghasilkan sisa limbah buangan (Tailing). Tailing mengandung logam berat berbahaya salah satunya Timbal (Pb). Meningkatnya konsentrasi Pb di perairan akan meningkat pula konsentrasinya dalam tubuh biota, salah satunya udang. Tujuan dilakukannya penelitian ini adalah menganalisis kandungan Pb pada insang, hepatopankreas dan daging pada Penaeus merguiensis, menganalisis kandungan Pb pada air dan sedimen, mengukur kemampuan Penaeus merguiensis dalam mengakumulasikan Pb di air dan sedimen, dan menentukan nilai batas aman konsumsi. Sampel udang, air dan sedimen dianalisis menggunakan AAS. Hasil penelitian menunjukkan bahwa konsentrasi Pb tertinggi pada Penaeus merguiensis adalah hepatopankreas>insang>daging, dengan kisaran rata-rata 0,1897–0,4064 mg/kg, insang 0,2424-0,4770 mg/kg, dan daging 0,1348-0,1636 mg/kg. Konsentrasi Pb rata-rata dalam air berkisar antara 0,2624-0,5713 mg/L, sementara sedimen berkisar dari 0,2783-0,9760 mg/kg. Kemampuan Penaeus merguensis untuk mengakumulasi Pb termasuk dalam kategori rendah. Nilai asupan harian sekitar 9,760-11,128 kg/minggu.

The two banana prawns Penaeus merguiensis and P. indicus are arguably the most commercially important species of penaeid prawns in the tropical and sub-tropical Indo-West Pacific region. They are fecund, short-lived, and have a complex life history involving offshore spawning, inshore mangrove-lined nursery grounds, and migrations between the two locations. We have reviewed and assessed published research on: the fisheries and aquaculture; taxonomy and identification; distribution and habitat preferences; growth; mortality; food and feeding; predation, and the importance of the mangrove habitat to banana prawns. We have examined the life history patterns of these two banana prawns and the many environmental and biological factors that affect different life history stages, often resulting in large interannual variations in abundances of adult prawns and commercial catches. We have also reviewed research on the ecosystem relationships involving these prawns, including fishery impacts on the environment and other species caught as bycatch. In reviewing the published information on factors affecting recruitment dynamics and variability, we have sometimes found contrasting and confounding results, suggesting that these factors are not yet fully understood. Therefore, for each aspect of the prawns' biology we have pointed to areas with incomplete or conflicted understanding, which will hopefully guide future research on these extremely valuable prawn species. [ABSTRACT FROM AUTHOR]

Modification of freshwater flow regimes can impact estuarine ecosystems at the receiving end of these flows. This is particularly true in tropical areas, such as the wet-dry tropics, where major freshwater flows in the wet season may result in prolonged and large-scale flooding, followed by periods of little or no flow during an extended dry season. Estuarine species, such as the commercially important prawn Penaeus merguiensis, have lifecycles adapted to seasonal flows. The potential effects of flow regulation on estimated catches of P. merguiensis were explored using a Bayesian belief network (BBN) model. Probability statements were generated about the ecological implications of different magnitudes of natural flow, as well as three water-extraction scenarios: 1) reduced flow in the wet season; 2) the introduction of flow in the dry season; and 3) the combination of scenario one and two. Thresholds of freshwater flow that affect the likelihood of high prawn catches in the fishery were identified, and the cumulative effects explored. This is the first time that these thresholds have been identified and the model suggests there is little capacity to regulate or modify the freshwater flow without reducing the probability of high prawn catches. [ABSTRACT FROM AUTHOR]

Mosquito cell lines (C6/36) were reported in the literature to support the propagation of Penaeus monodon hepandensovirus (PmoHDV). We aim to evaluate the susceptibility and viral propagation of P. merguiensis hepandensovirus (PmeHDV) which is ∼22% different to PmoHDV in Aedes albopictus cell line (C6/36). Cellular changes in the infected cell culture were detected. Vacuole formation was seen in both infected and uninfected cell cultures. The average number of disrupted cellular membranes in the infected cells (presumptive dead cells) was significantly higher than that of uninfected cells at passage two (F = 9.749, d.f. 1, 22, p < 0.05). Using a proliferation assay, light absorption of infected cells peaked at 2 weeks post-infection (O.D. = 0.27) but was significantly lower than that of the uninfected groups (O.D. = 0.37) (F = 6.879, d.f. 1, 94, p < 0.05) suggesting hindered cell growth. PCR of the serial passages of the infected cell cultures indicated weak positive results for PmeHDV infection and TaqMan quantitative PCR confirmed that the average number of viral copies declined from 3.8 × 10 5 to 5.69 × 10 2 copies per μL and the mean of cycle times increased from 19.26 to 27.63. These results are interpreted to mean C6/36 allows the initial stage of PmeHDV replication, but the virus was incapable of using C6/36 for patent replication of its’ virions. [ABSTRACT FROM AUTHOR]

Decapod Hepandensovirus 1 (HDV), formerly known as hepatopancreatic parvovirus, has been associated with stunting, lowered production and outright mortalities in prawns in aquaculture. Despite the fact that broodstock are sourced and aquaculture farms are planned in the regions of northern and Western Australia, data on these parvoviruses from this region are limited. The prevalence of HDV in Penaeus esculentus and Penaeus merguiensis is moderate (34–51%) in southern Western Australia, Exmouth Gulf and the Gulf of Carpentaria but statistically higher (P < 0.05) in Shark Bay (82%). We speculate this is due to the topography of Shark Bay combined with the currents of the Indian Ocean gyre (IOG). Despite an on average 8–12% genomic heterogeneity, the nucleotide sequences of HDV in WA most closely align with HDV in regions associated with the IOG; Thailand, India, Tanzania, Madagascar; eastern Asia, Korea and less commonly, with sequences from the eastern coast of Australia. This potentially changes the paradigm of a single strain of HDV being ubiquitous in Australia and there was little risk in moving broodstock from WA to the eastern states, so there was no testing of broodstock for HDV. There is no strong evidence to clarify whether the strain of HDV in WA P. esculentus came from either its' nearest genetic relatives, P. monodon or P. semisulcatus or from P. merguiensis from the Solanderian province of Australia. P. esculentus HDV appears to be most related to strains within the IOG. The HDV nucleotide heterogeneity of wild prawns contrasts strongly to studies undertaken with prawns from aquaculture where genetic selection may have occurred. [ABSTRACT FROM AUTHOR]

Biotechnology of enzyme has gained popularity due to the growing need for novel environmental technologies and the development of innovative mass-production. The work describes the original application of biosensors based on Penaeus merguiensis alkaline phosphatase (PM ALP) immobilized on gold nanorods (GNRs) to heavy metal determination. Penaeus merguiensis alkaline phosphatase (PM ALP) was immobilized on gold nanorods (GNRs) by ionic exchange and hydrophobic interactions. The optimum pH and temperature for maximum enzyme activity for the immobilized PM ALP are identified to be 11.0 and 60 °C, respectively, for the hydrolysis of para-Nitrophenylphosphate ( p- NPP). The kinetic studies confirm the Michaelis–Menten behavior and suggests overall slightly decrease in the performance of the immobilized enzyme with reference to the free enzyme. K m and V max values were 0.32 µm and 54 µm. min −1 for free and 0.39 µm and 48 µm min −1 for immobilized enzymes, respectively. Similarly, the thermal stability, storage stability and stability at extreme pH of the enzyme is found to increase after the immobilization. The inhibitory effect heavy metal ions was studied on free and immobilized PM ALP. The bi-enzymatic biosensor were tested to study the influence of heavy metal ions and pesticides on the corresponding enzyme. The obtained high stability and lower decrease in catalytic efficiency suggested the great potential and feasibility of immobilized PM ALP nanobiocatalyst in efficient and apply the biosensor in total toxic metal content determination. [ABSTRACT FROM AUTHOR]

It has been established that baculovirus-insect cell line is applicable for shrimp virus replication, propagation and secretion in the in vitro culture system. We thus aimed to produce Macrobrachium rosenbergii nodavirus (MrNV) clone within S2 cell to improve viral production over the previous model using Sf9 cell. Upon the transfection of genomic RNA1 and RNA2 into S2 cells, the recognizable cellular changes including cytoplasmic swelling and clumping of cells were observed within 24 h. The culture media containing secreted MrNV particles were re-transfected into healthy S2 cells and similar cellular changes as with the first transfection were observed. Immunohistochemistry analysis of the re-infecting S2 cell revealed an intense immunoreactivity against MrNV capsid protein confirming that S2 cell was permissive cells for MrNV. In vivo infectivity test using P. merguiensis as a model animal exposed to the secreted MrNV revealed the presence of RNA2 fragment in shrimp tissue accompanied with the sign of whitish abdominal muscle at 24 h post-infection (p.i.). In addition, the number of shrimp hemocytes decreased at 6–24 h p.i. and returned to the normal level at 48 h p.i., whereas a significant up-regulation of immune-related genes including HSP70 and trypsin was noted. These data suggested that rescued MrNV produced in S2 is practically useful for MrNV infection test in which their natural virion inoculae are difficult to obtain. In addition, the molecular basis of viral pathogenesis can further be investigated which should be beneficial for any antiviral therapy developments in the future. • S2 cells improved production of MrN infectious virions over Sf9 cells. • MrNV could infect P. merguiensis in vivo and cause white tail disease. • MrNV infection decreased number of hemocyte and altered the expression of immune-related gene of P. merguiensis. [ABSTRACT FROM AUTHOR]

The ability of three proteases producing bacteria such as Pseudomonas aeruginosa , Serratia marcescens , and Bacillus pumilus on the demineralization and deproteinzation efficiency of shrimp waste, for chitin extraction, was investigated. Statistical analysis of data was showed a significant difference between the percentage of demineralization and deproteinization in different bacteria species ( p < 0.05). The highest deproteinization (74.76%) and demineralization rate (78.46%) was obtained with P. aeruginosa and the lowest was observed in the treatment of S. marcescens . Then, chitin was converted to chitosan by deacetylation in the presence of NaOH 50%. The antioxidant activity of chitosan solution was determined using different tests. The highest activity (DO 700 nm = 0.74, DO 695 nm = 0.31) was observed for chitosan sample at concentration of 1000 μg/ml. The antioxidant potential of the hydrolysates was also evaluated. The highest reducing power in a volume of 400 μl hydrolysate of S. marcescens and the highest total antioxidant capacity in a volume 100 μl hydrolysate of B. pumilus were observed. These results indicated that the P. aeruginosa bacterium in comparison with other bacterial strains, higher ability to remove proteins and mineral from shrimp waste. Therefore, the use of this bacterium is recommended for protein and mineral removal from marine crustaceans. [ABSTRACT FROM AUTHOR]

Hemocyanin (HC) was purified from hemolymph of Fenneropenaeus merguiensis (de Man, 1888). Purified HC showed one band in non-denaturing PAGE with a molecular mass of 457 kDa, determined by gel filtration. Using an ELISA, HC content was 85.6% of total hemolymph protein. HC's hexamer form contained no phenoloxidase activity under trypsin or SDS activation. FmHC, cloned from F. merguiensis, had a full-length cDNA comprised of 2128 bp with an open reading frame encoding a peptide of 661 amino acids with two Cu-binding sites. Expression of FmHC was found only in the hepatopancreas where it was up-regulated after exposure to Vibrio harveyi injection into shrimp and with tissue incubations. HC protein levels in the hemolymph of bacterial injected shrimp also increased. FmHC expression was also up-regulated after shrimp were challenged with a lipopolysaccharide, which is a surface component of gram-negative bacteria. These results indicate that HC is inducible and up-regulated in response to pathogenic challenge, confirming that HC participates in the innate immune response in F. merguiensis. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the population dynamics ofPenaeus merguiensisstock in the coastal waters of the Persian Gulf. A total of 4994 male and 5264 female prawns were collected monthly by a bottom-trawl net, from July 2010 to September 2012. The carapace length and weight relationship demonstrated that growth in both sexes was allometric. The asymptotic carapace length (CL∞) was estimated at 48 mm for males and 54 mm for females. The growth parameterKwas calculated as 1.6 Yr− 1for males and 1.8 Yr− 1for females. The total mortality rate for males was more than that for females. And the exploitation rates were 0.75 for males and 0.69 for females. The sex ratio identified that it was not a constant 1:1 throughout the year, with 51.3% females. Banana prawns can spawn all year round and have a spawning peak from February to May. The Lm50%was estimated at a carapace length of 33.64 mm. The exploitation ofP. merguiensisin the area is intended to protect spawners and juvenile stock for renewal. Also, the results showed that long-term monitoring is still required to better understandP. merguiensispopulation dynamics. [ABSTRACT FROM PUBLISHER]

Penaeus merguiensis hepandensovirus (PmeDV) is a strain of the hepatopancreatic parvoviruses that causes overt mortalities and stunting in survivors in many penaeids around the tropical and temperate world. This study was to investigate if RNA interference (RNAi) could be used to ameliorate pre-existing PmeDV infection in a therapeutic manner rather than in a simultaneous exposure when delivered via live bacteria in pelleted food. One hundred and fifty Australian Penaeus merguiensis testing positive for PmeDV by PCR were divided into 5 treatment groups which were bled weekly for viral copies measured by real time PCR and treated for 5 weeks with the appropriate RNAi. The treatments were no treatment control, carrier fish oil, plasmid delivered nonspecific RNAi, plasmid delivered specific RNAi and plasmid delivered specific RNAi in live Escherichia coli . Statistically, the specific RNAi microencapsulated in live E. coli was the best overall treatment against pre-existing PmeDV when delivered in the food. Specific RNAi in bacterial cells had the lowest mortality (P < 0.0001), the highest relative percentage survival (68%), most prawns with no detectable viral copies (53%) and it was equal to the nonspecific RNAi with the lowest viral copies when virus was detected (P < 0.0001). The naked plasmid, specific RNAi and the nonspecific RNAi as plasmids were very similar being the next most protective across all measures. The week of the trial was not significant (P > 0.05), but the week by treatment interaction was (P < 0.05) with the number of RNAi-control prawns significantly increasing viral copies at week 2 whilst copies in other treatments fell. Also, fish oil lost its protective effects by 5 weeks as evidenced by statistically increased number of viral copies. Overall, this study showed that RNAi microencapsulated in live E. coli and fed via pelleted feed could increase survival of P. merguiensis and lower viral copies in pre-existing infections of PmeDV. This methodology herein should be the simplest for farmers to apply and when utilized, these results should allow farmers to increase yields, profitability and therefore, sustainability. [ABSTRACT FROM AUTHOR]

Biomass, catchability, and natural mortality are key parameters in fish stock assessment. Yet, it is difficult to estimate these quantities, especially natural mortality, when only fishery data are available. Using a method of population depletion analysis, we estimated these population and biological quantities for the white banana prawn (Penaeus merguiensis) in Australia's valuable Northern Prawn Fishery. In addition, we directly included fishing power change over time. The models were implemented in a Bayesian framework by incorporating process error, observation error, and random variability for the underlying parameters. The posterior median initial fishable biomass ranged from ∼2000 to 7000 t year−1, and the median catchability varied from ∼3.8 × 10−4 to 7.3 × 10−4 boat-day−1, resulting in an average fishing power increase of 2.6% per year. An unexpected result is the estimate of exponential natural mortality rate of ∼0.03 week−1. This value is substantially lower than an earlier estimate of 0.05 week−1, which was based on a single year's fishery data in one stock region and has been widely used for over four decades without validation. We attribute this low natural mortality estimate mainly to prawn aggregation behaviour. [ABSTRACT FROM PUBLISHER]

A major decline in the catch of the banana prawn [shrimp], Penaeus (Fenneropenaeus) merguiensis, occurred over a six-year period in the Weipa region of the northeastern Gulf of Carpentaria, Australia. Three main hypotheses have been developed to explain this decline: (1) prawn recruitment collapsed due to overfishing; (2) recruitment collapsed due to a change in the prawn's environment; and (3) adult banana prawns were still present, but fishers could no longer effectively find or catch them. Qualitative mathematical models were used to link population biology, environmental factors, and fishery dynamics to evaluate the alternative hypotheses. This modeling approach provides the means to rapidly integrate knowledge across disciplines and consider alternative hypotheses about how the structure and function of an ecosystem affects its dynamics. Alternative models were constructed to address the different hypotheses and also to encompass a diversity of opinion about the underlying dynamics of the system. Key findings from these analyses are that: instability in the system can arise when discarded fishery bycatch supports relatively high predation pressure; system stability can be enhanced by management of fishing effort or stock catchability; catch per unit effort is not necessarily a reliable indicator of stock abundance; a change in early-season rainfall should affect all stages in the banana prawn's life cycle; and a reduced catch in the Weipa region can create and reinforce a shift in fishing effort away from Weipa. Results from the models informed an approach to test the hypotheses (i.e., an experimental fishing program), and promoted understanding of the system among researchers, management agencies, and industry. The analytical tools developed in this work to address stages of a prawn life cycle and fishery dynamics are generally applicable to any exploited natural resource. [ABSTRACT FROM AUTHOR]

Mangroves are traditionally considered to provide important nutrition to tropical estuarine consumers. However, there is still controversy about this, and the extent and importance of these inputs are largely unquantified. In particular, there is no information for food webs of small estuaries that dominate wet-dry tropical coasts, where freshwater inflow is intermittent, leading to highly seasonal inputs of nutrients from terrestrial systems. Since the relative importance of the different sources depends on the type and extent of different habitats and on hydrological and topographic conditions, results from other regions/type of systems cannot be extrapolated to these estuaries. Here, δC is used to determine the importance of mangrove-derived carbon for Penaeus merguiensis (detritivore; shrimp), Ambassis vachellii (planktivore; fish), and Leiognathus equulus (benthivore; fish) from six small wet-dry tropical estuaries that differ in mangrove (C) cover and in type of terrestrial vegetation adjacent to the estuary. Bayesian mixing models confirmed that mangrove material was important to consumers in all estuaries. There was a gradient in this importance that agreed with the extent of mangrove forests in the estuaries, as C sources were the most important contributors to animals from the three estuaries with the greatest (>40 %) mangrove cover. There was also evidence of incorporation of C material for the three estuaries with lower (<30 %) mangrove cover. Since these latter estuaries had no adjacent terrestrial C forests, the detected C influence can only be of mangrove origin. This shows that mangroves are important contributors to these food webs, underlining the importance of mangroves in supporting estuarine nursery ground value and fisheries productivity. [ABSTRACT FROM AUTHOR]

This study investigated short-term effects of high temperature on survival and feed consumption of the tropical banana shrimp Penaeus merguiensis. Three 7-day experiments were conducted with three age group of P. merguiensis : PL 25 (postlarvae 25 days old), PL 50 and PL 100. In these experiments water temperature was maintained at 27 °C in the control, but increased to 32, 35, 38 and 41 °C at a constant rate of 1 °C every 8 h. Once reached, the desired level of water temperature was kept stable until the end of the experiment. Results showed that water temperature above 35 °C significantly reduced survival of the experimental shrimp (P < 0.01). Shrimp survival was only 24% and 0% in the 38 °C and 41 °C treatments, respectively while ranging between 91 and 96% in the other treatments. Feed consumption was significantly affected by both ambient water temperature and shrimp size (P < 0.01). It was highest in the 41 °C treatment (1.7%/shrimp×day), followed by the 38 °C treatment (1.3%/shrimp×day) (P < 0.01). Feed consumption in the PL 50 and PL 100 age groups was 3.5 to 4.0 fold higher than that in the smallest age group PL 25 (P < 0.01). This study suggests that P. merguiensis in tropical areas may survive water temperature up to 35 °C in commercial shrimp ponds. • This study is reports short-term tolerance of Penaeus merguiensis to high water temperatures. • Shrimp survival were not different from 27 to 35oC, but significantly reduced at 38oC and 41oC (P < 0.01) • Feed consumption was not different from 27 to 35oC, but significantly increased at 38oC and 41oC (P < 0.01) • P. merguiensis could be farmed during the hot season when water temperature may reach 35oC. [ABSTRACT FROM AUTHOR]