Now showing items 1-20 of 3061

    • Article

      Mortality of pond-cultured Litopenaeus vannamei associated with acute hepatopancreatic necrosis disease (AHPND) and white spot syndrome virus (WSSV) infection in the Philippines 

      LD de la Peña, NAR Cabillon, EC Amar, DD Catedral, RC Usero, JP Faisan Jr., JI Arboleda, WD Monotilla, AT Calpe, DD Fernandez & CP Saloma - Fish Pathology, 2017 - Japanese Society of Fish Pathology
      Mortalities of up to 60% were observed in pond-cultured Litopenaeus vannamei in Bohol, Philippines. Histopathological examination revealed typical acute hepatopancreatic necrosis disease (AHPND) pathology. PCR test generated 1,269 bp and 230 bp amplicons confirmative for the toxin-producing AHPND strain of Vibrio parahaemolyticus among shrimp sampled from eight ponds. The same samples were subjected to PCR analyses for the presence of other viruses, namely WSSV, IHHNV, IMNV, and TSV. The samples were negative for the viruses except WSSV, which was detected after one-step PCR in six out of eight ponds. These results suggested that shrimp were infected dually with AHPND V. parahaemolyticus and WSSV.
    • Article

      A probiotic Bacillus strain containing amorphous poly-beta-hydroxybutyrate (PHB) stimulates the innate immune response of Penaeus monodon postlarvae 

      JLQ Laranja, EC Amar, GL Ludevese-Pascual, Y Niu, MJ Geaga, P De Schryver & P Bossier - Fish and Shellfish Immunology, 2017 - Elsevier
      In this study, the PHB-accumulating Bacillus sp. JL47 strain (capable of accumulating 55% PHB on cell dry weight) was investigated for its effects on the immune response of giant tiger shrimp (Penaeus monodon) postlarvae (PL) before and after the Vibrio campbellii challenge. Briefly, shrimp PL were cultured and fed with Artemia nauplii enriched with Bacillus sp. JL47. Shrimp receiving the Artemia nauplii without JL47 enrichment were used as control. After 15 days of feeding, the shrimp were challenged with pathogenic V. campbellii LMG 21363 at 106 cells mL-1 by immersion. Relative expression of the immune related genes encoding for prophenoloxidase (proPO), transglutaminase (TGase) and heat shock protein 70 (Hsp70) in the shrimp were measured before (0 h) and after (3, 6, 9, 12, 24 h) the Vibrio challenge by quantitative real-time PCR using β-actin as the reference gene. The expressions of TGase and proPO were significantly up-regulated (p < 0.05) within 9 h and 12 h, respectively after challenge in shrimp receiving the Bacillus sp. JL47 as compared to the challenged and non-challenged controls. Hsp70 expression was significantly increased (p < 0.05) at 3 h post-challenge in all challenged shrimp. Interestingly, proPO and TGase genes were significantly up-regulated (p < 0.05) in Bacillus sp. JL47 treated shrimp even before the Vibrio challenge was applied. No up-regulation in the Hsp70 gene, however, was observed under these conditions. The data suggest that the protective effect of the PHB-accumulating Bacillus sp. JL47 in shrimp was due to its capacity to stimulate the innate immune related genes of the shrimp, specifically the proPO and TGase genes. The application of probiotic Bacillus species, capable of accumulating a significant amount of PHB, is suggested as potential immunostimulatory strategy for aquaculture.
    • Article

      Optimum low salinity to reduce cannibalism and improve survival of the larvae of freshwater African catfish Clarias gariepinus 

      G Kawamura, T Bagarinao, ASK Yong, PW Sao, LS Lim & S Senoo - Fisheries Science, 2017 - Springer Verlag
      The freshwater African catfish Clarias gariepinus is carnivorous and cannibalistic even during the larval and juvenile stages and this behavior causes economic losses in aquaculture. This study examined for the first time the effect of salinity on cannibalism, survival, and growth of African catfish larvae in the hatchery. Larvae (4 days old, median 7.8 mm TL, 2.8 mg BW) of the African catfish were reared for 21 days at nominal salinity 0, 1, 2, 3, 4, 5, 6, and 7 ppt. After 21 days, they grew to 10–39 mm (median 22 mm) and 10–490 mg (median 90 mg), with no significant difference by salinity treatments. Survival ratios were similarly low (24–31%) at 0, 1, 3, and 7 ppt and significantly higher (49–55%) at 2, 4, 5, and 6 ppt. Cannibalism was significantly lower, 15–30% at 4–6 ppt, than the 40–50% at 0–3 and 7 ppt. Size variation was lower at 4–6 ppt and higher at 0–3 and 7 ppt. We recommend hatchery rearing of African catfish at the optimum low salinity of 4–6 ppt rather than in full fresh water at least up to 21 days. This rearing method fosters larval welfare and improves hatchery production.
    • Article

      Shelter colour preference of the postlarvae of the giant freshwater prawn Macrobrachium rosenbergii 

      G Kawamura, T Bagarinao, ASK Yong, TC Fen & LS Lim - Fisheries Science, 2017 - Springer Verlag
      The addition of artificial shelters of various materials has been used in Macrobrachium rosenbergii tanks and ponds as a means of increasing productivity. The present study investigated the shelter colour preference of M. rosenbergii postlarvae (age 15–18 days after metamorphosis) in the laboratory. Shelter occupancy tests were performed on four groups of 200 postlarvae in four 57-l aquaria, into which were placed shelters made of rigid coloured netting sewn into four-layered cubes open on two sides. The shelters were presented in six colour pairs: black vs dark green, black vs light green, black vs blue, dark green vs light green, dark green vs blue, and light green vs blue. Colour preference was tested six times for each colour pair. The data obtained were analyzed using Thurstone’s law of comparative judgment. The mean z-score was significantly highest (i.e., highest preference) for the black shelter. Vision was involved in the detection of and approach to the shelter. When released in aquaria, intact-eyed individual postlarvae directly approached the shelter straight away, whereas blind postlarvae (paint over the eyes) swam around randomly and occupied the shelter only after accidental contact much later. Postlarvae in open water out of the shelter exhibited frequent aggressive contact, while those in the shelter were quiescent. The use of black shelters in rearing tanks is thus recommended for reducing stress and aggression among M. rosenbergii postlarvae in the hatchery.
    • Article

      Clonal production of Kappaphycus alvarezii (Doty) Doty in vitro 

      MRJ Luhan & JP Mateo - Journal of Applied Phycology, 2017 - Springer Verlag
      Micropropagation has proven to be a reliable method to mass produce certain crops. This method also has been applied in macroalgae to produce clones for seaweed farming. Protocols for callus production and shoot regeneration from protoplasts have been established for some seaweed species like Kappaphycus alvarezii. Cells and larger tissues, whether in solid or suspension medium, have been used to propagate clones which were later tested for suitability for farming. Although clonal production was successful, the long duration of culture in vitro limits the production process making the growing of Kappaphycus in vitro an expensive technique to produce clones. In this study, K. alvarezii was grown in vitro to develop a more efficient protocol for the production of clones. Small sections of Kappaphycus were grown in suspension for 1 month under the same temperature, light, and salinity. The type of media, source of explants, length of explants, and stocking density that resulted in the highest growth rate and survival rate were determined. Growth rate of K. alvarezii is significantly higher in media with inorganic nitrogen added than in Grund medium or Ascophyllum nodosum medium only. The appearance of shoot primordia as early as 5 days was observed in media with higher nitrogen concentration. Growth rates of explants approximately 3 and 5 mm are significantly higher than 10 mm sections. Shoots develop significantly faster in explants from tips than sections from older branches. Growth rate of K. alvarezii grown at 0.5, 0.75, 1, 1.25 s 10 mL−1 of medium is not significantly different. This protocol could significantly reduce the (1) time of culture and (2) cost of plantlets production by not using plant growth regulators and formulated media in vitro. Nursery reared plantlets/propagules for farming would be affordable to the stakeholders for sustainability of seaweed production.
    • Book chapter

      Luminous Vibrio and the greenwater culture of the tiger shrimp Penaeus monodon with tilapia 

      GD Lio-Po - In PW Perschbacher & RR Stickney (Eds.), Tilapia in Intensive Co-culture, 2017 - John Wiley & Sons, Ltd
      Luminous vibriosis is a devastating infection of penaeid shrimp larvae and juveniles causing heavy mortalities. To counter the bacterial pathogen, Vibrio harveyi, shrimp farmers in the Philippines modified their growout culture method of the black tiger shrimp, Penaeus monodon, juveniles and developed the greenwater culture technique. This culture method involves the use of pond water of all-male, saline-tolerant Oreochromis hornorum as rearing water for the culture of shrimp juveniles in ponds. Such a modified culture of P. monodon juveniles was found effective in preventing the onset of luminous vibriosis. Basic studies revealed that antiluminous Vibrio factors are inherent in the bacterial, fungal, and microalgal flora of the tilapia water, dermal mucus, and gut that singly or collectively inhibit the growth of V. harveyi, in vitro. The skin mucus studies of other brackishwater fish species showed that the siganids, Siganus guttatus, and red hybrid tilapia (Oreochromis niloticus × Oreochromis mossambicus), as well as sea bass, Lates calcarifer, are promising alternative fish species for this novel shrimp culture method. A review of pond-simulated studies in tanks and ponds, similarly, confirmed these findings and the impact of the greenwater culture technique on water quality, including its economic benefits to the farmer. The greenwater culture of shrimp can sustain the successful production of shrimp juveniles by inhibition of the luminous Vibrio. This culture method is also currently used in the growout culture of the white shrimp, Litopenaeus vannamei.
    • Article

      Growth and feed performance, digestibility and acute stress response of juvenile grouper (Epinephelus fuscoguttatus) fed diets with hydrolysate from milkfish offal 

      REP Mamauag & JA Ragaza - Aquaculture Research, 2017 - Wiley
      Nutritional qualities of fish processing by-products can further be improved through enzymatic hydrolysis. The objective of this study was to elucidate the efficacy of hydrolysed milkfish offal at different inclusion levels when fed to juvenile grouper, Epinephelus fuscoguttatus, with an initial body weight of 2.88 ± 0.06 g. The animals were fed for 56 days with seven diets supplemented with 0 (control), 5%, 15% and 25% of milkfish offal (MO) and milkfish offal hydrolysate (MOH). The diets were formulated to be isonitrogenous (45%) and isolipidic (11%). The diets were assigned to 21 tanks (15 fish per tank) with each diet having three replicates. Results from the experimental trials indicated that feed conversion efficiency, feed intake and weight gain of fish significantly (P < 0.05) improved when fed diets with MOH. No significant differences within the rest of the dietary treatments were observed. Survival rate (>90%) did not differ in all the dietary treatments. Proximate composition (crude protein, crude fat and ash) indicated no significant difference among fish fed from all the dietary treatments. Apparent digestibility of MOH indicated a 95% and 66% digestibility for protein and dry matter respectively. Plasma stress parameters (cortisol and glucose) were not influenced by the dietary treatment when fish were subjected to an acute stressor (5-min chasing). Liver morphology indicated normal hepatocyte shape and the presence of lipid droplets in fish fed from all the dietary treatments. The results indicated that milkfish offal processed as hydrolysate can be utilized in grouper diets and can promote growth and feed efficiency when supplied at 10–15%.
    • Article

      Temporal changes in innate immunity parameters, epinecidin gene expression, and mortality in orange-spotted grouper, Epinephelus coioides experimentally infected with a fish pathogen, Vibrio harveyi JML1 

      EC Amar, JP Faisan Jr., MJS Apines-Amar & RV Pakingking Jr. - Fish and Shellfish Immunology, 2017 - Elsevier
      Changes in innate immunity parameters and epinecidin mRNA transcript levels were examined to characterize the non-specific immune response of E. coioides to pathogenic V. harveyi JML1 isolated from affected cage-cultured fish. After fish had been injected with bacteria at a dose causing 30% mortality, blood and tissue samples were collected at 0, 6, 12, 24, 48, 72, 96, 120, and 240 h post-infection (hpi) for assessment of indices such as the oxidative burst (OB) and phagocytic index (PI) of head kidney cells, and lysozyme activity (LYS) and total immunoglobulin (Total Ig) levels of the plasma. The epinecidin mRNA transcript levels (EGE) from skin, gills, liver, kidney, and spleen tissues were also determined by gelbased RT-PCR. Lastly, daily mortality (DM), liver total bacterial load (TBC), and presumptive Vibrio count (TVC) were monitored up to 240 hpi. The results revealed that bacteria proliferated rapidly in fish tissue, reaching peak densities at 24 hpi for both TBC and TVC but was on a downward trend thereafter. The pattern in fish mortality closely correlated with TBC and TVC. Total Ig, OB, and PI in E. coioides were suppressed in the early part of infection when V. harveyi load was high but recovered and later increased as bacterial density declined. LYS and EGE were consistently high and their activities were not hampered by bacterial infection. The study demonstrated that V. harveyi JML1 interacts with E. coioides by transiently inhibiting some immune parameters resulting in mortalities. However, consistently high LYS, upregulated EGE, and resurgent PI, OB and Total Ig conferred resistance and subsequent recovery in the fish. The study provides new insights on the interaction between E. coioides and V. harveyi JML1 that can aid in formulating health management strategies for groupers. Further studies on prophylactic interventions to enhance the innate immune response in grouper during infection with V. harveyi JML1 are suggested.
    • Article

      Substrate preference for burying and feeding of sandfish Holothuria scabra juveniles 

      JP Altamirano, CP Recente & JC Rodriguez Jr. - Fisheries Research, 2017 - Elsevier
      Substrate preference for both burying and feeding of sandfish Holothuria scabra juveniles (3–6 g wet body weight) and their associated daily behavior, growth and survival were investigated in laboratory and field experiments using different coastal substrate types (silty mud, sandy mud, and coarse sand) to determine the ideal habitat for potential grow-out culture, sea ranching or stock enhancement of this important sea cucumber species. During the peak hours of burying (03:00–09:00 h) and feeding (15:00–03:00 h), a significantly greater number of sandfish juveniles preferred to bury in (28.3%) and feed on (21.5%) sandy mud, typical of intertidal coastal sand flats. Silty mud was the least preferred substrate for feeding (13.5%) and burying (13.8%). Burying and feeding preferences of sandfish juveniles were not significantly influenced by the presence of seagrass (Thalassia hemprichii) on coarse sand. Growth of sandfish juveniles in the first two weeks of rearing in tanks was significantly greater on coarse sand (growth rate: 0.59 g d−1 or 7.0% d−1), followed by sandy mud (0.34 g d−1 or 4.72% d−1) while OM content of these sediments remain almost unchanged. On silty mud, sandfish juveniles constantly shrunk (−0.02 g d−1 or −0.63% d−1) for 8 weeks while sediment OM content increased. In the field, silty mud substrate of a mangrove pond caused total mortality of sandfish within two weeks, while sandy mud substrate of a sand flat provided significantly higher growth than the control (no sediment), but not significantly different than coarse sand of a seagrass bed. Sandy mud to coarse sand substrates of intertidal sand flats were most preferred by sandfish juveniles while silty mud associated with muddy mangroves and culture ponds seems to be unsuitable that sandfish would opt to avoid. Our results will contribute to the selection of suitable sites for sandfish sea ranching and stock enhancement in coastal areas.
    • Article

      Nutritional evaluation of distiller's dried grain with soluble as replacement to soybean meal in diets of milkfish, Chanos chanos and its effect on fish performance and intestinal morphology 

      REP Mamauag, JA Ragaza & TJ Nacionales - Aquaculture Nutrition, 2017 - Wiley
      A 90-day feeding trial was conducted on milkfish, Chanos chanos with an initial mean body weight of 3.07 ± 0.17 g (mean ± standard error of mean). Six treatment diets were formulated to contain 0 g/kg (Diet 1), 150 g/kg (Diet 2), 25 g/kg (Diet 3), 300 g/kg (Diet 4), 350 g/kg (Diet 5) and 450 g/kg (Diet 6) distiller's dried grain with soluble (DDGS). All the dietary treatments were isonitrogenous (350 g/kg crude protein) and isolipidic (6% crude lipid). Result of the feeding trial indicated that growth rates, feed intake and feed efficiency were not significantly (p > .05) affected by inclusion levels of DDGS by up to 450 g/kg in the feed. Proximate body composition (crude protein, crude lipid, ash, fibre) in fish fed the dietary treatments were not significantly (p > .05) affected as well. The DDGS when used as a milkfish ingredient has a protein digestibility of 910 g/kg, fat disgetsibility of 850 g/kg, carbohydrate digestibility of 750 g/kg and a dry matter digestibility of 520 g/kg Results from the intestinal morphology displayed no apparent pathological changes in the digestive tract of fish fed all dietary treatments. These results indicate that DDGS can be efficiently utilized by milkfish by up to 450 g/kg without negatively affecting performance parameters and intestinal morphology.
    • Article

      Colour discrimination in dim light by the larvae of the African catfish Clarias gariepinus 

      G Kawamura, T Bagarinao, PK Hoo, J Justin & LS Lim - Ichthyological Research, 2017 - Springer
      Many demersal fish species undergo vertical shifts in habitats during ontogeny especially after larval metamorphosis. The visual spectral sensitivity shifts with the habitat, indicating a change in colour vision. Colour vision depends on sufficient ambient light and becomes ineffective at a particular low light intensity. It is not known how fishes see colour in dim light. By means of a behavioural experiment on larval African catfish Clarias gariepinus in the laboratory, we determined colour vision and colour discrimination in dim light. Light-adapted larvae were subjected to classical conditioning to associate a reward feed with a green or a red stimulus placed among 7 shades of grey. The larvae learned this visual task after 70 and 90 trials. A different batch of larvae were trained to discriminate between green and red and then tested for the ability to discriminate between these colours, as the light intensity was reduced. The larvae learned this visual task after 110 trials in bright light and were able to discriminate colours, as light was dimmed until 0.01 lx, the minimal illuminance measurable in this study, and similar to starlight. The retinae of the larvae were found to be light adapted at 0.01 lx; thus indicating cone-based colour vision at this illuminance. For comparison, three human subjects were tested under similar conditions and showed a colour vision threshold at between 1.5 and 0.1 lx. For the larvae of C. gariepinus, the ability of colour discrimination in dim light is probably due to its retinal tapetum, which could increase the sensitivity of cones.
    • Article

      Quality assessment of newly hatched mud crab, Scylla serrata, larvae 

      ET Quinitio, JJ dela Cruz-Huervana & FD Parado-Estepa - Aquaculture Research, 2017 - Wiley
      Starvation and exposure to formalin were investigated as possible stress tests for evaluating the quality of mud crab, Scylla serrata, larvae. For the starvation stress test, newly hatched zoeae stocked in 150-ml containers were either starved or fed rotifers. Similarly, newly hatched zoeae were stocked in containers with seawater of 0 (control), 20, 30 and 40 mg/L formalin for the formalin stress test. The zoeae from the same batches were used for seed production to monitor their performance and validate the results of stress tests. Starvation was found to be unsuitable for larval quality evaluation. However, the impact of initial food deprivation on the newly hatched larvae indicates that feeding immediately after hatching is necessary for mud crab larvae. Exposure of larvae to 40 mg/L formalin for 3 hr appeared to be a reliable and practical method for larval quality assessment as the survival of larvae in the mass production tanks validated the classification of good and poor quality batches in the stress tests. On this basis, a hatchery operator can decide which batch should be cultured further. Finally, there appears to be a link between the quality of larvae and the performance at the megalopa and early juvenile crabs.
    • Article

      Use of agar-bound microparticulate diet as alternative food for tropical abalone, Haliotis asinina (Linnaeus 1758) post-larvae in large-scale cultures 

      MN Bautista-Teruel, JRH Maquirang, MR de la Peña & VT Balinas - Aquaculture International, 2017 - Springer Verlag
      The efficacy of using agar-bound microparticulate diet (A-MPD) as alternative food for abalone Haliotis asinina Linne post-larvae in large-scale culture was investigated. Larvae sourced from the hatchery-bred (HB) and wild-sourced (WS) broodstock were fed with either diatoms (TMT1-NF), agar-bound microparticulate diet (TMT2-A-MPD), or a combination of both feeds (TMT3-NF + A-MPD) in six 2-m3 tanks replicated over time. Three hundred thousand veliger larvae were stocked/tank containing 80 corrugated plates with mucus trails hanging on bamboo poles. Feeds were given at 0900 h starting at day 3 with seawater flow through introduced every 1400 h starting day 5. Two-way analysis of variance determined significant differences (p < 0.05) in survival and shell length between larval sources and feed types. Tukey’s post hoc test established differences among treatment means. At day 30, survival for HB- and WS-sourced larvae was significantly higher (42%) in TMT3 compared with TMT2 having 35% for HB and 38% for WS (p < 0.05). Larvae fed with TMT1 had significantly lowest survival among the three treatments. Survival at 60 and 90 days did not show significant difference for TMT2 and TMT3 regardless of broodstock source. Post-larval shell growth (90 days), from both sources fed with TMT2 and TMT3, was significantly higher than TMT1 (p < 0.05). Larval performance did not show any significant interactions between HB and WS broodstock. The use of A-MPD alone or in combination may elicit improvement in survival and shell length growth in abalone larvae regardless of larval sources. A-MPD may be used as full or partial replacements to diatoms as alternative food for abalone post-larvae in large-scale culture.
    • Article

      Abdominal segment deformity syndrome (asds) and fused body segment deformity (fbsd) in cultured Penaeus indicus 

      The abdominal segment deformity disease (ASDD) is a new shrimp disease reported only in cultured Penaeus vannamei in Thailand. Shrimp with ASDD have deformed abdominal segment, jagged gut line and bumpy surfaces. Similar signs were observed in cultured P. indicus in the Philippines. However, aside from the signs described for ASDD, some P. indicus showing abdominal segment deformity syndrome (ASDS) had more severe deformities up to the extent that the number of body segments was reduced due to fusion. Shrimp with fused body segment deformity (FBSD) had four instead of five pairs of legs. To account the prevalence of the deformities in P. indicus, shrimp were classified into grossly normal shrimp (NS), shrimp with abdominal segment deformity syndrome (ASDS) and shrimp with fused segments (FBSD). Out of the shrimp sampled, 83.4 ± 5.4% was NS, 10.9 ± 6.2% was ASDS and 5.7 ± 3.0% was FBSD. Morphometric characteristics of the shrimp were measured. There was no significant difference in body weight (BW) among male and female NS, ASDS and FBSD. In both sexes, total length (TL) of FBSD was significantly shorter compared to NS and ASDS. Shrimp samples were also screened to be negative for known infectious viral diseases including white spot syndrome virus (WSSV), infectious hypodermal and haematopoietic necrosis virus (IHHNV), infectious myonecrosis virus (IMNV), P. vannamei nodavirus (PvNV), Macrobrachium rosenbergii nodavirus (MrNV) and Taura syndrome virus (TSV). Occurrence of ASDS and FBSD in post-larvae (PL) produced from captive and wild spawners were also determined. Based on a tank experiment, no significant difference was detected between the percentages of ASDS in PL produced from wild or captive spawners but FBSD was only noted in PL produced from the latter. Deformities generally did not affect the size of P. indicus except for the reduced length of shrimp with FBSD which when coupled with missing pleopods could lead to major economic loss for shrimp farmers if not addressed properly.
    • Article

      Morphological deformities in mud crab Scylla serrata juveniles exposed to antibiotics during the larval stage 

      GS Pates Jr., ET Quinitio & FD Parado-Estepa - Aquaculture Research, 2017 - Wiley
      The effects of antibiotics on the external deformities, growth and survival of mud crab Scylla serrata larvae and juveniles were determined. Zoeae were exposed to oxytetracycline (OTC) (0, 3.0, 6.0, 9.0, 12 mg L-1) and furazolidone (FZD) (0, 0.5, 1.0, 1.5, 2.0 mg L-1) in the first and second experiments, respectively, until the late megalopa. The crab instars were grown in nursery tanks for 1 month. Larvae survived until megalopa only at 3.0 and 6.0 mg L-1 OTC or 0.5 and 1.0 mg L-1 FZD. These four concentrations were run simultaneously in another experiment. Morphological deformities in zoea 5 were bent dorsal, rostral and furcal spines. There was no significant difference (P > 0.05) on the deformities of zoea 5 in 3.0 and 6.0 mg L-1 OTC and 0.5 and 1.0 mg L-1 FZD. Significantly (P < 0.05) higher survival and faster growth were attained in 3.0 mg L-1 OTC and 0.5 mg L-1 FZD. Deformities observed in juveniles were fused frontal and lateral spines, asymmetrical and depressed tip of abdominal flap and gap between sternites. High percentage occurrence of deformities was observed in the 6.0 mg L-1 OTC and 1.0 mg L-1 FZD in the first and third experiments, respectively. There was no significant difference (P > 0.05) observed in the survival of juveniles in OTC and FZD treatments. However, growth was significantly (P < 0.05) faster in lower concentrations of the two antibiotics. The study shows the effects of OTC and FZD in the morphology of mud crab. Therefore, there is a need to eliminate the use of antibiotics and find alternatives.
    • Conference paper

      Development of protocol for the production of hatchery-reared mud crab Scylla serrata juveniles for soft-shell crab farming 

      ET Quinitio, GX Libunao & FD Parado-Estepa - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Development of economically viable techniques for growing hatchery-reared juvenile crabs to suitable sizes will address the problem on the source of seed stocks for soft-shell crab farming. This paper reports the production of hatchery-reared mud crab Scylla serrata from juveniles in the nursery to 73-106 g body weight (BW) crabs in the grow-out pond for the individual system soft-shell crab farming. Likewise, the performance of hatchery-reared S. serrata, and wild S. tranquebarica and S. olivacea juveniles was determined in the soft-shell crab production set-up.

      The BW increased from 1.8-1.9 g to 78-113.7 g when stocked at 0.5 ind m-2 and from 1.6-2.3 g to 73-106.7 g at 1.0 ind m-2 after 75 days. Growth rates at both stocking densities were comparable. However, survival was significantly higher (P<0.05) in lower (63.6~c1.01%) than in higher (35.6~c3.34%) stocking density. Male S. serrata (46.0 ~c 1.75%) had significantly higher BW increase than females (39.4 ~c 2.05%). Crabs stocked at sizes of 51-60 g showed significantly greater percent increase in BW (43.26~c 0.98%) compared with those at 61-70 g (40.98~c1.33%), 71-80 g (38.55~c 1.04%), 81-90 g (36.34 ~c 1.27%) and 91-100 g (38.52 ~c 1.67%). Among the three species, hatchery-reared S. serrata (42.14 ~c 1.34%) had significantly higher mean percent BW increase compared with S. olivacea (38.23 ~c 0.49%) and S. tranquebarica (36.16 ~c 0.78%). S. serrata had significantly shorter mean culture period (24.11 ~c 0.95 days) than S. tranquebarica (28.48 ~c 0.54 days) and S. olivacea (28.75 ~c 0.34 days).
    • Conference paper

      Strategies to reduce disease incidence in mud crab culture 

      EC Amar, MD Somera, SB Madero, EA Tendencia & JP Faisan Jr. - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Mud crab hatchery suffers from low survival due to susceptibility to bacterial infection in the early larval stages among many causes. Despite food safety issues, antibiotics continue to be used in the absence of effective alternatives. In this study, screening of plant extracts was conducted to determine their suitability as antimicrobial agents against pathogens causing low survival in the hatchery. In addition, potential probionts were isolated from the gastrointestinal tract of mud crab, and water and sediments of mud crab grow-out ponds.

      Crude ethanolic extracts from various terrestrial and mangrove trees were tested for in vitro antimicrobial activity and toxicity to mud crab zoea and megalopa. In addition, the in vivo antimicrobial efficacies of the selected extracts were tested by oral administration followed by experimental challenge with Vibrio harveryi. On the other hand, the putative probionts, were tested for pathogenicity against mud crab zoea and megalopa and quorum sensing inhibition activity against V. harveyi. Finally the extracts and probionts were tested for their efficacy in simulated hatchery and grow-out trials.

      Results showed that extracts of Terminalia cattapa and the potential probiont Bacillus subtilis G100R11 showed antimicrobial and probiotic activity in in vitro and in vivo tests. In simulated hatchery trials, T. cattapa administration successfully produced crab instar with a survival of 1.3-1.8% in trials 1 and 2 comparable to antibiotic control. B. subtilis produced crab instar with survival of 0.8-1.0% in trials 1 and 2, better than the commercial probiotic with 0-0.13% survival. Using T. cattapa and B. subtilis, survival was above 30% until zoea 5 but suddenly dropped below 5% during metamorphosis to megalopa where high incidence of incomplete molting was observed. If difficulty affecting the molting process is addressed, high survival from zoea to megalopa and crab instar will be achievable.
    • Conference paper

      Pilot scale production of pellets suitable for mud crab Scylla serrata 

      RM Coloso, MR Catacutan, JP Peralta, JG Genodepa, K Duno & R Gardoce - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Studies were conducted towards the pilot scale production of stable and nutritionally adequate pellets suitable for mud crab Scylla serrata to help in efforts to increase mud crab production in the Philippines. Preliminary studies showed that mud crabs preferred pellets which were spherical or cylindrical and contained marine based attractants. Two practical diets were formulated and prepared in the Pilot Feed Mill of SEAFDEC/AQD. The extruded diets, along with a commercial mud crab grow-out diet, were subjected to proximate and Ca/P analyses as well as cholesterol analysis and water stability tests. The diets were fed to crabs in a controlled laboratory experiment using fiberglass tanks with flow-through, aerated seawater, and monitored from initial molt (M0) up to the second molt (M2). Tests revealed that the crabs fed Diet 1 (CP 48.28 %, CF 7.74 %, Ca 5.23%, P 12.93 %, cholesterol 0.173 %) showed the highest growth and better survival than those fed Diet 2 or commercial diet. Crabs fed Diet 1 took a shorter time to attain two molt cycles from M0. Survival was 70% after M2. Diet 1 was water stable within two hours. Abnormalities were observed including absent swimming legs or chelae, exposed gills, sores on exoskeleton, incomplete molting, or soft exoskeleton, but none that could be directly attributed to a specific treatment. Incomplete molting and slow hardening of the exoskeleton in crabs that accounted for the mortalities could be due to the low cholesterol levels in the diets especially in the commercial diet which had the lowest cholesterol level. Cholesterol supplementation of the artificial diet would be needed to improve molting success and survival of mud crabs in grow-out culture. The results of these experiments will be used to formulate a cost-effective grow-out diet for mud crab (supported by DOST-PCAARRD Grant in Aid).
    • Conference paper

      Development of immunostimulant for mud crab, Scylla serrata 

      RF Traifalgar - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Non-specific immune activitation is considered a potential prophylactic approach in the prevention of disease outbreaks in crustacean aquaculture. The present investigation evaluates the dietary supplementation of bacterial and algal derived immunostimulants including peptidoglycan, ergosan, mannan oligosaccharide and acidic polysaccharides from Ulva, Sargassum and Padina to enhance the immunological responses and resistance of Scylla serrata juveniles against white spot syndrome virus (WSSV) infection. Each of the test immunostimulant was optimized for dose and frequency of administration.

      Results showed significant enhancement of shrimp survival against WSSV infection if Mannan oligosaccharide is supplemented at 2000 mg kg-1 diet applied every 3 days. Optimum dose and frequency of application for peptidoglycan was determined as 1000 mg kg-1 diet applied every 3 days while a dose of 2000 mg kg-1 diet applied every 3 days was found optimum for ergosan. Enhancement of survival was also observed in crabs given the acidic polysaccharide extracts from seaweeds. Better survival was observed in the treatment receiving Ulva at 1000 mg kg-1 applied every 3 days. Similar dose and frequency were also observed to enhance the resistance of the juvenile crabs against WSSV when maintained with diets supplemented with Padina and Sargassum acidic polysaccharides. The high survival in these treatments is associated with the prominent enhancement of immunological responses including phenol oxidase activity, respiratory burst and total hemocyte counts. At optimum dosage and application frequency, these immunostimulants are observed to improve overall growth performance of the juvenile crab. These results suggest that dietary supplementation of peptidoglycan, ergosan mannan oligosaccharide, and acidic polysaccharides from Ulva, Sargassum and Padina at a dose described above can be used to boost the immunological response and enhance the resistance of S. serrata juveniles against WSSV infection.
    • Conference paper

      Handling, storage and transport conditions of mud crabs in trading centers 

      JP Peralta & JPD Chan - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This study aims to improve the handling, storage and transport conditions of mud crabs. The usual practice of the crab growers in the Philippines is to bring the market size crabs to middlemen, brokers or operators of small trading centers immediately after harvest; then the crabs are brought to municipal traders or operators of bigger buying station. The crabs are sent to the exporters in Manila or Cebu. The crabs are exported mostly to Singapore, Taiwan, Hongkong and mainland China. The crabs are classified based on the species, body weight, sex, gonad maturity and intactness of limbs. Crabs are rejected for export when they are soft-shelled, very lean, or have incomplete limbs and abnormalities. Crabs with emaciated muscle (‘hagas’), ammoniacal odor (strong urine-like smell) and in an undesirable state are also rejected.

      This paper presents the initial results of the project on the Improvement in the handling, storage and transport of mud crabs under Sub-program C entitled Improvement of Feeds and Stock Management Practices in Mud Crab Grow-out Culture under the National Mud Crab Science and Technology Program. It also presents issues and concerns on the present practices, and presents possible recommendations.