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  Article

  Immunization regimen in Asian sea bass (Lates calcarifer) broodfish: A practical strategy to control vertical transmission of nervous necrosis virus during seed production 

  R Pakingking Jr., EG de Jesus-Ayson, O Reyes & NB Bautista - Vaccine, 2018 - Elsevier

  Outbreaks of viral nervous necrosis (VNN) in Asian sea bass (Lates calcarifer) at the larval stages via vertical transmission of nervous necrosis virus (NNV) from asymptomatic broodfish remain as a major deterrent during seed production. A five-year study was conducted to produce NNV-specific-free sea bass broodfish reared in land-based tanks through an annual immunization regimen with the formalin-inactivated NNV. We primarily immunized (intraperitoneal injection) sea bass juveniles (5 g) and monitored the neutralizing antibody (Nab) titers in the sera of these fish at scheduled intervals post-immunization. Nab titers in the sera of immunized fish peaked at Month 2 (titer: 1:4480 ± 1185) but thereafter gradually declined and significantly dropped (1:260 ± 83) at Month 12 post-primary immunization. Booster immunization of these fish at Month 12 post-immunization led to abrupt increases in Nab titers in booster immunized (B-Im) fish at Month 1 (1:12800 ± 6704) but thereafter declined and dropped at Month 12 (1:480 ± 165) post-booster immunization. The annual booster injections with the inactivated vaccine or L-15 (Unimmunized [U-Im]) were consecutively conducted for 4 years until the fish became sexually mature. Mature fish from both groups were successively induced to spawn twice (1-month interval) via intramuscular injection with luteinizing hormone-releasing hormone analogue (LHRH-a; 100 µg/kg BW). NNV was not detected by RT-PCR in oocytes and milts, and spawned eggs of B-Im fish. In contrast, oocytes and milts, and spawned eggs of U-Im fish were NNV positive. Spawned eggs of B-Im broodfish exhibited Nab titers ranging from 1:192 ± 34 to 1:240 while such was not detected (<1:40) in eggs of U-Im fish. Taken together, current data clearly demonstrate that annual immunization regimen with inactivated NNV vaccine is a pragmatic approach for sustaining immunocompetent sea bass broodfish reared in land-based tanks and circumvent the risk of vertical transmission of NNV from asymptomatic broodfish to their offspring under stress of repetitive spawning.
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  Article

  Status of sea cucumber fishery and populations across sites with different levels of management in Palawan, Philippines 

  JBS Jontila, HM Monteclaro, GF Quinitio, SM Santander-de Leon & JP Altamirano - Ocean and Coastal Management, 2018 - Elsevier

  This study was conducted to investigate the sea cucumber fishery and compare populations between exploited and unexploited sites. Three islands were selected, the Arrecife Island as the unexploited site and the Johnson and Green Islands representing the exploited sites. In each site, sea cucumber species richness, diversity and densities were assessed by laying as much as 15 transects (50 m × 5 m) per habitat in each island. Differences in species richness, diversity and relative densities across sites and habitats were tested using a Two-way Analysis of Variance (ANOVA) and Tukey test for post hoc comparisons. An interview with gatherers, key informants and focus group discussions were also conducted to gather information on the sea cucumber fishery and its management. Results showed that the unexploited site had a higher species richness (14 vs. 7 and 7). Relative density of species was also higher in the unexploited site at 1245 ind ha^-1 while it was only 78 and 39 ind ha^-1 in exploited sites (p < 0.05). Interviews and a focus group discussion revealed that national regulations on permit system and size limits were not enforced at the local level and that gatherers had low levels of awareness regarding regulations on sea cucumber harvest. Current management measures appear to be ineffective and insufficient, leaving the sea cucumbers in areas open to exploitation at risk of depletion. Given that sea cucumbers provide substantial income to local communities, the depletion of this resource could compromise the livelihood of people in island communities that rely heavily on marine resources for living. Thus, this study highlights the need to review national policies on sea cucumber fishery and place the management at the local level.
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  Newsletter

  AQD Matters 2018 May - June 

  RH Ledesma (Ed.) - 2018 - Aquaculture Department, Southeast Asian Fisheries Development Center
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  Article

  Larval rearing of mud crab (Scylla): What lies ahead 

  K Waiho, H Fazhan, ET Quinitio, JC Baylon, Y Fujaya, G Azmie, Q Wu, X Shi, M Ikhwanuddin & H Ma - Aquaculture, 2018 - Elsevier

  The increasing global demand for mud crabs (genus Scylla) and threats to the wild populations highlight the urgency of fully rearing them in captivity. Despite considerable progress in mud crab production, most crab farms still rely heavily on wild-caught crablets and juveniles while the low and inconsistent success rates of larviculture remain as the main bottleneck impeding the development of mud crab aquaculture. Over the years, numerous studies have been conducted to determine the optimum larval rearing parameters, the ontogenic changes in digestive function and feeding behaviour, and the diets for different larval stages. These data, however, are dispersed and not summarised to inform culture practices. This review provides an update on the current progresses and to pinpoint the gaps in knowledge regarding mud crab larval rearing. We include all four mud crab species under the genus Scylla, i.e. Scylla serrata, Scylla olivacea, Scylla tranquebarica and Scylla paramamosain. Knowledge compiled in this review serves as an important guideline for prospective mud crab larviculture. Future research should gear towards filling in the gaps in our knowledge to advance mud crab larval rearing, thus fully incorporating mud crab into the aquaculture sector.
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  Article

  Low ph water impairs the tactile sense of the postlarvae of the giant freshwater prawn Macrobrachium rosenbergii 

  G Kawamura, T Bagarinao, ASK Yong, SN Noor & LS Lim - Tropical Life Sciences Research, 2018 - Penerbit Universiti Sains Malaysia

  The effect of low pH on the tactile sense of Macrobrachium rosenbergii postlarvae was determined in the laboratory by means of two behavioural assays: shelter (netting) occupancy and jumping response to touch stimuli (taps) by a glass micropipette. The postlarvae were acclimated to pH 4, pH 5, pH 6 and pH 7.5 (control) in 45 L aquaria 5−7 d before the experiments. Shelter occupancy decreased with pH and was significantly lower at pH 4 and pH 5 than at pH 6 and in the control. The jumping response instantly followed a tap 93−98% of the time in the control, pH 6 and pH 5 treatments. However, the postlarvae showed significantly lower jumping response (65%) at pH 4, indicating an impaired tactile sense. Low pH 4−5 probably degrades the chitin of the sensory setae and inhibits the surface mechanoreceptors of the prawn postlarvae.
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  Article

  Does age matter?: The information-seeking behavior of Filipino aquaculture researchers 

  DL Superio - Journal of Library Administration, 2018 - Taylor & Francis

  Findings of previous studies revealed that regardless of the objective, age does affect the information-seeking behavior of an individual. Likewise, this study found the same results. Although all of the younger Filipino aquaculture researchers preferred the Internet to begin their search process, it was found that they were more frequent library users, and more reliant on librarians than their older counterparts. Likewise, they preferred the combination of print and electronic formats when reading. Thus, they would print and save the retrieved electronic copy of information at least very often. The study is a valuable addition to the information-seeking behavior studies on Filipinos, and the first to tackle the effects of age on the information-seeking behavior of Filipino aquaculture researchers.
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  Article

  Responsible aquaculturists: The information-seeking behavior of milkfish farmers in Iloilo, Philippines 

  DL Superio, ES Nemiz, MGH Oliveros, VEV Pacullo, AMA Yap-Zerrudo & JB Canaman - Information Development, 2018 - SAGE Publications

  Compliance with a policy, law, standard or code requires understanding of its provisions. However, for someone to understand it, he must be aware of its existence and be provided access to it. A qualitative-quantitative research was conducted to determine the awareness of milkfish farmers about the Philippine Code of Practice for Aquaculture in the municipalities of Leganes and Zarraga, Iloilo Province, the Philippines and their information-seeking behaviors. Results revealed that the majority of the respondents were not aware of the existence of the Code, hence, there is a low level of compliance. When seeking everyday life information, the majority of the milkfish farmers depended on television, personal or person-to-person communication and radio, while when seeking for fish farming information, personal communication was the preferred source. None of the respondents was aware of the existence of their municipal libraries.
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  Newsletter

  AQD Matters 2018 January - February 

  RH Ledesma (Ed.) - 2018 - Aquaculture Department, Southeast Asian Fisheries Development Center
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  Article

  Characterisation of Vibrio isolates recovered from the eyes of cage-cultured pompano (Trachinotus blochii) infested with caligid parasites (Lepeophtheirus spinifer) 

  R Pakingking Jr., NB Bautista, D Catedral & EG de Jesus-Ayson - European Association of Fish Pathologists Bulletin, 2018 - European Association of Fish Pathologists

  Exophthalmia was documented among sea cage-cultured pompano (Trachinotus blochii) broodstocks with caligid parasite (Lepeophtheirus spinifer) infestation in the Philippines. Following sequencing, and based on the results of both diagnostic investigations and infection experiments, V. harveyi likely had a role in the reported exophthalmia cases, and this was initiated by L. spinifer infection.
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  Newsletter

  AQD Matters 45th Anniversary Special Issue 

  RDB Dianala (Ed.) - 2018 - Aquaculture Department, Southeast Asian Fisheries Development Center
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  Article

  Dietary onion or ginger modulates the stress response and susceptibility to Vibrio harveyi JML1 infection in brown-marbled grouper Epinephelus fuscoguttatus juveniles 

  EC Amar, MJS Apines-Amar & JP Faisan Jr. - Journal of Aquatic Animal Health, 2018 - American Fisheries Society

  Onion Allium cepa and ginger Zingiber officinale have health‐promoting properties that qualify them as functional foods. The effect of repeated acute stressors was examined in juvenile Brown‐marbled Grouper Epinephelus fuscoguttatus that were fed four diets supplemented with onion at 1.8%, ginger at 1.8%, vitamin C at 0.86%, and β‐glucan at 0.8% of the diet. The non‐supplemented diet served as the control. After 12 weeks of feeding, fish were exposed to stressors and were experimentally infected with a fish pathogen, the bacterium Vibrio harveyi JML1. After repeated exposure to hypoxia, cortisol levels rose significantly in the non‐supplemented fish compared to those fed onion, ginger, β‐glucan, or vitamin C. Within groups, postexposure cortisol levels in the onion‐, ginger‐, and vitamin C‐fed fish did not change relative to pre‐stress levels, whereas significant increases in poststress values were observed in the control and β‐glucan groups. The net cortisol increase was also significantly greater in the non‐supplemented group compared to the supplemented groups. The net cortisol increase did not vary among the supplemented groups except that the β‐glucan‐fed group exhibited a higher net increase than the onion‐fed group. Similarly, repeated acute exposure to osmotic stress significantly increased the plasma cortisol level in the non‐supplemented group compared to groups that received supplements; no differences were found in the supplemented groups except the β‐glucan group. Within groups, significant increases in poststress values relative to pre‐stress levels were found only in the control and β‐glucan groups. Repeated acute exposure to hypoxia significantly increased cumulative mortality in the control group compared to the supplemented groups (except the β‐glucan group), whereas repeated exposure to acute osmotic stress significantly increased cumulative mortality only in the control group 10 d after infection with V. harveyi JML1. Based on our collective results, most of the supplemented groups performed better than the control, but the best supplements were onion and ginger in terms of enhancing stress tolerance and increasing survival of Brown‐marbled Grouper upon infection with V. harveyi JML1.
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  Article

  Limit of colour vision in dim light in larvae of the giant freshwater prawn Macrobrachium rosenbergii 

  G Kawamura, TU Bagarinao, ASK Yong, AB Faisal & LS Lim - Fisheries Science, 2018 - Springer Verlag

  Colour vision depends on sufficient ambient light and becomes ineffective at a particular low light intensity. It is not known how decapod crustaceans see colour in dim light. In the present study we investigated the colour vision threshold in larvae of the giant freshwater prawn Macrobrachium rosenbergii in a tank under natural illumination. Plastic beads of different colours (blue, red, yellow and white) in various combinations were suspended in the tank. The larvae swam straight toward the beads and gathered around them. The number of larvae was highest on the blue and white beads. The luminance in the tank was then gradually decreased by covering it with different numbers of layers of black cloth, and the response of the larvae to the beads was video-recorded under infrared illumination. The preference for blue and white beads remained manifest as the luminance was reduced from 418 to 0.07 cd/m², but not at 0.02 cd/m², indicating a colour vision threshold between 0.07 and 0.02 cd/m². The larvae have apposition compound eyes with large optical parameters, comparable to those of apposition eyes of nocturnal insects, which presumably capture more light and show enhanced sensitivity, enabling the larvae to see colour in dim light.
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  Article

  Genetic assessment of milkfish (Chanos chanos Forsskal) stocks based on novel short tandem repeats for marker-aided broodstock management 

  MRR Romana-Eguia, BS Santos, M Ikeda, ZU Basiao & A Kijima - Aquaculture Research, 2018 - John Wiley and Sons

  Milkfish hatchery broodstock are either from on-grown wild-caught or hatchery-produced fry/juveniles. To determine if a marker-assisted management scheme can be formulated for improved milkfish hatchery production, milkfish stocks were genetically characterized using nine novel short tandem repeats or microsatellites. Eight wild-bred Philippine stocks (CLA, CUR, CAM, SIH, SBH-I1, HH, PAL and ZH-P₀), four hatchery-bred stocks (SBH-I2, SBH-D, BoH and ZH-F₁), two farm stocks of known mixed lineages (SPH and BDH) and one Indonesian hatchery-bred stock (WJH) were assessed. WJH was included since milkfish fingerlings from Indonesia reared in Philippine farms could be developed into future broodstock. Mean allelic richness (Ar) was highest in wild-bred stocks (9.5) and lowest in hatchery-bred spawners (9.1). Mean expected heterozygosities (He) were relatively similar in all stocks with wild-bred stocks slightly higher (0.67) than the others. An analysis of molecular variance indicated significant yet low genetic differentiation among stocks (F_ST = 0.013; p = .000) where variation (98.6%) was explained by intra-stock differences. In some of the domesticated stocks, reductions in mean allelic richness were observed in first generation hatchery broodstock (e.g. ZH-F₁; Ar = 8.3), compared with their founder stock (e.g. ZH-P₀; Ar = 9.4). The Indonesian stock was similar to local wild-bred stocks based on genetic variability indices; thus, it might be likely that the local stocks’ fitness traits could be comparable with the imported milkfish stock which has been perceived to be better. The quality of locally available farmed milkfish and prospects of formulating a broodstock management scheme for the production of good quality milkfish seedstock are herewith discussed.
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  Newsletter

  AQD Matters 2018 March - April 

  JMV de la Cruz (Ed.) - 2018 - Aquaculture Department, Southeast Asian Fisheries Development Center
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  Article

  Effects of the dietary fermented tuna by-product meal on growth, blood parameters, nonspecific immune response, and disease resistance in juvenile olive flounder, Paralichthys olivaceus 

  FO Oncul, FA Aya, A Hamidoghli, S Won, G Lee, KR Han & SC Bai - Journal of the World Aquaculture Society, 2018 - World Aquaculture Society

  This study evaluated the effects of dietary fermented tuna by‐product meal (FTBM) in juvenile olive flounder, Paralichthys olivaceus. Five diets were formulated to replace fishmeal (FM) with FTBM at 0% (FTBM₀), 12.5% (FTBM_12.5), 25.0% (FTBM₂₅), 37.5% (FTBM_37.5), or 50% (FTBM₅₀). After 8 wk, weight gain, specific growth rate, and feed efficiency of fish fed FTBM₀ and FTBM_12.5 diets were significantly higher than fish fed the other diets (P < 0.05). Also, mean cumulative survival rates (%) of fish fed the FTBM₀ and FTBM_12.5 diets were significantly higher than those fed FTBM₅₀ diet at Day 9 postchallenge with Edwardsiella tarda (P < 0.05). Protein efficiency ratio of fish fed FTBM₀ and FTBM_12.5 diets was significantly higher (P < 0.05) than fish fed diets FTBM_37.5 and FTBM₅₀. Broken‐line regression analysis of weight gain showed an optimal FM replacement level of 10.65% with FTBM. Therefore, the optimal dietary inclusion of FTBM in juvenile olive flounder diets could be greater than 10.65% but less than 12.5% without any adverse physiological effects on fish health.
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  Article

  Phylogeographic patterns in the Philippine archipelago influence symbiont diversity in the bobtail squid-Vibrio mutualism 

  RL Coryell, KE Turnham, EG de Jesus Ayson, C Lavilla-Pitogo, AC Alcala, F Sotto, B Gonzales & MK Nishiguchi - Ecology and Evolution, 2018 - Wiley Open Access

  Marine microbes encounter a myriad of biotic and abiotic factors that can impact fitness by limiting their range and capacity to move between habitats. This is especially true for environmentally transmitted bacteria that cycle between their hosts and the surrounding habitat. As geologic history, biogeography, and other factors such as water temperature, salinity, and physical barriers can inhibit bacterial movement to novel environments, we chose to examine the genetic architecture of Euprymna albatrossae (Mollusca: Cephalopoda) and their Vibrio fischeri symbionts in the Philippine archipelago using a combined phylogeographic approach. Eleven separate sites in the Philippine islands were examined using haplotype estimates that were examined via nested clade analysis to determine the relationship between E. albatrossae and V. fischeri populations and their geographic location. Identical analyses of molecular variance (AMOVA) were used to estimate variation within and between populations for host and symbiont genetic data. Host animals demonstrated a significant amount of variation within island groups, while symbiont variation was found within individual populations. Nested clade phylogenetic analysis revealed that hosts and symbionts may have colonized this area at different times, with a sudden change in habitat. Additionally, host data indicate restricted gene flow, whereas symbionts show range expansion, followed by periodic restriction to genetic flow. These differences between host and symbiont networks indicate that factors “outside the squid” influence distribution of Philippine V. fischeri. Our results shed light on how geography and changing environmental factors can impact marine symbiotic associations at both local and global scales.
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  Article

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

  ET Quinitio, JJ dela Cruz-Huervana & FD Parado-Estepa - Aquaculture Research, 2018 - 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.
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  Article

  Parasites from the green mussel (Perna viridis Linnaeus 1758) (Mollusca: Mytilidae) of Ivisan, Capiz, Philippines 

  G Erazo-Pagador - Philippine Agricultural Scientist, 2018 - College of Agriculture and Food Science, University of the Philippines Los Baños

  This study reports the parasites found in green mussel (Perna viridis L.) from Ivisan, Capiz, Philippines. Samples were collected monthly from January to December 2009. A total of 360 samples were collected, fixed in 10% formalin in seawater solution, and processed by standard histological techniques that included staining the sections with hematoxylin and eosin (H & E). The water temperature ranged from 24 to 30°C and salinity from 18 to 23 ppt. Microscopic analysis showed that the most prevalent parasites were Nematopsis sp. occurring mostly in connective tissues (46%), metacestodes of Tylocephalum sp. in the mantle (12%), and a turbellarian (4%) and metacercariae in the mantle (4%). Based on these findings, these parasites may not yet be a problem to mussel farming as they were low and caused no apparent damage to the host.
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  Article

  Microalgal paste production of the diatom Chaetoceros calcitrans using electrolytic flocculation method at optimum culture conditions 

  MR de la Peña, AV Franco, HP Igcasan Jr., MDGN Arnaldo, RM Piloton, SS Garibay & VT Balinas - Aquaculture International, 2018 - Springer Verlag

  The optimum culture conditions of the local strain Chaetoceros calcitrans were determined to improve biomass and reduce cost of production. Under outdoor culture conditions, higher cell density was attained when the cultures were enriched with Tungkang Marine Research Laboratory (TMRL) medium composed of cheap technical grade reagents and cultured at 25 g L⁻¹ salinity. The cultures were lighted with two 40 W cool-white GE fluorescent tubes (24–35 μmol photon m⁻² s⁻¹). Using semi-continuous culture system under established optimum culture conditions, C. calcitrans can be re-cultured thrice and concentrated at each culture cycle using electrolytic flocculation method to produce 4.6 kg m⁻³ of diatom paste. The viability of concentrated C. calcitrans after 3 months of storage was comparable to live diatom cells. Simple preservation technique by low-temperature storage is convenient for storing algal concentrates for use as starter cultures and for feeding invertebrates. The paste costs USD 8.24 kg⁻¹ inclusive of the assets and flocculation materials for culturing and harvesting the diatom, respectively. This study established the suitable conditions for mass culture of C. calcitrans and produced concentrated diatoms in paste form that is readily available for aquaculture hatcheries at a lower cost.
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  Report

  SEAFDEC/AQD Highlights 2017 

  Aquaculture Department, Southeast Asian Fisheries Development Center - 2018 - Aquaculture Department, Southeast Asian Fisheries Development Center

  SEAFDEC/AQD Highlights 2017 is SEAFDEC/AQD’s annual report updating on its accomplishments and progress for the year 2017.

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