Southeast Asian Fisheries Development Center
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Genomic analysis of Vibrio harveyi strain PH1009, a potential multi-drug resistant pathogen due to acquisition of toxin genes
No full textThe following is the Supplementary data to this article: Download .xls (8.95 MB)In has increasingly been observed that viral and bacterial coinfection frequently occurs among cultured shrimp and this coinfection could exacerbate the disease phenotype. Here, we describe a newly discovered bacterial strain, Vibrio harveyi PH1009 collected from Masbate Island, Philippines that was found to be co-infecting with the White Spot Syndrome virus a sample of black tiger prawn, Penaeus monodon. The genome of V. harveyi PH1009 was sequenced, assembled, and annotated. Average Nucleotide identity calculation with Vibrio harveyi strains confirmed its taxonomic identity. It is a potential multi-drug and multi-heavy metal resistant strain based on the multiple antibiotic and heavy metal resistance determinants annotated on its genome. Two prophage regions were identified in its genome. One contained genes for Zona occludens toxin (Zot) and Accessory cholera toxin (Ace), essential toxins of toxigenic V. cholerae strains apart from CTX toxins. Pan-genome analysis of V. harveyi strains, including PH1009, revealed an “open” pan-genome for V. harveyi and a core genome mainly composed of genes necessary for growth and metabolism. Phylogenetic tree based on the core genome alignment revealed that PH1009 was closest to strains QT520, CAIM 1754, and 823tez1. Published virulence factors present on the strain QT520 suggest similar pathogenicity with PH1009. However, PH1009 Zot was not found on related strains but was present in strains HENC-01 and CAIM 148. Most unique genes found in the PH1009 strain were identified as hypothetical proteins. Further annotation showed that several of these hypothetical proteins were phage transposases, integrases, and transcription regulators, implying the role of bacteriophages in the distinct genomic features of the PH1009 genome. The PH1009 genome will serve as a valuable genomic resource for comparative genomic studies and in understanding the disease mechanism of the Vibrio harveyi species.This research was funded by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology, Philippines. We acknowledge the Philippine Shrimp Pathogenomics Program members for their help in collecting, processing, and analyzing various isolates; and the Department of Science and Technology Science Education Institute for funding support to C.A.D.M. and R.M.M
Effect of size grading on growth of yellow Pacific shortfin eel (Anguilla bicolor pacifica)
No full textHeterogeneous growth, which is common among farmed fish, can be remedied by size grading. This study focused on whether the size grading process, which is commonly practiced in aquaculture, improves the subsequent growth performance of the Pacific shortfin eel Anguilla bicolor pacifica. Eels [338.70 ± 4.70 mm total length (TL) and 84.93 ± 1.87 g body weight (BW)] were initially reared for 60 days (pre-size grading period) and manually divided into three size groups: small (≤115 g), large (>150 g) and mixed (>115 g but <170 g), all maintained at a density of 5 kg m−3 and reared until day 150 (size grading period). After size grading, mean BW and TL at harvest significantly differed in all eel groups, suggesting growth was size specific. Nonetheless, at day 150, except for biomass, size grading had no significant effect on growth and survival, coefficient of variation of length and weight, and Fulton's condition factor. Large eels had a significantly higher feed intake than mixed or small eels, whereas feed efficiency did not differ among eel groups. Results suggest that size grading promotes size-specific growth but did not improve the overall growth performance of yellow stage of A. bicolor pacifica.This study was supported by grant funds from the Japan ASEAN Integration Fund (Br-02-Y2018B) and the Government of Japan-Trust Fund (8300-B-RD-FD0415 and 8300-B-RD-FD0120)
Promoting tropical eel culture in the Philippines: Comparative performance of Anguilla bicolor pacifica and A. marmorata in captivity
No full textEel aquaculture is an important activity in Southeast Asian countries such as Indonesia, Philippines, and Viet Nam. With the decline in the wild fishery stock of cold-water eel species (European eel Anguilla anguilla, Japanese eel A. japonica, and American eel A. rostrata (Tatsukawa, 2003; Gómez-Limia et al., 2022), there has been an increasing interest in the culture of tropical eel species as an export commodity. In the Philippines, species of anguillid eels cultured are mainly the Pacific shortfin eel A. bicolor pacifica and the giant mottled eel A. marmorata. Anguilla bicolor pacifica is now being considered as an alternative to A. japonica (Muthmainnah et al., 2016), being the most preferred eel species for consumption in East Asian countries. However, A. marmorata, which comprised the bulk of the wild glass eel catch in the Cagayan River, Philippines, has rarely been cultured as an export commodity. Comparison of performance and feed utilization may provide relevant information on the culture requirements of these two eel species under cage conditions
Culture of natural food for farmed freshwater fish and prawn larvae
No full textThis manual describes the various methods for culturing microalgae and other natural food organisms fed to freshwater fish/prawn larvae that are produced and reared in hatcheries. Hence, it will encourage/ promote the use of natural food organisms be these live and/or processed (concentrated algal pastes), as a means of optimizing larval fish/prawn production.
The manual was written purposely for local freshwater fish/prawn hatchery owners/operators and their technicians. The authors prepared the manual for hatchery operators to have a better understanding of how and why there is a need to culture natural food organisms as part of the standard larval rearing protocol and to increase/boost fish and/or prawn seedstock production.Englis
Comparison of reproductive aspects of the tropical eel Anguilla bicolor (McClelland 1884) in freshwater and estuarine habitats
No full textThe tropical anguillid eel, Anguilla bicolor McClelland, experiences significant growth up to the adult size in both freshwater and estuarine ecosystems, encountering salinity gradients that may impact their reproduction. Therefore, this study aimed to investigate the reproductive aspects of A. bicolor collected from Serayu River (freshwater) and Segara Anakan (estuary), Cilacap, Central Java, during July 2020 field surveys. The examined parameters included eye index (EI), fin index (FI), gonadosomatic index (GSI), hepatosomatic index (HSI), and sex ratio of eel specimens in freshwater and estuary. Furthermore, the total length (TL) and body weight (BW) ranged from 260 - 630 mm and 18 - 419 g in freshwater, and 260 - 630 mm and 18 - 447 g in estuary. Significant differences (P<0.01) were observed in the reproductive characteristics between the two habitats (P<0.01), with higher eye index, fin index, gonadosomatic index, and hepatosomatic index in freshwater-caught eels than the values obtained in estuary inhabitants. The mean of these four parameters were 6.99 ± 2.98%, 4.08 ± 0.71%, 1.70 ± 1.13%, and 1.92% ± 1.07 in freshwater, while 3.48 ± 1.60%, 3.45 ± 0.479%, 1.12 ± 0.23%, and 0.28 ± 0.19% were found in estuary. The sex ratio was significantly affected by habitat, with female eels dominating in freshwater (62.5%) compared to estuary (32%). These results suggested that eels in freshwater habitats might exhibit early gonadal maturation compared to those in estuary
AQD Matters 2023 July - August
No full textIn this issue: 1) SEAFDEC/AQD's new facilities to boost milkfish, shrimp production; 2) Chief Baliao graces bilateral talk between PH, Papua New Guinea; 3) Executive Committee members engage in dialogue at global aquaculture conference; 4) Strengthening bonds and cultivating skills: The SEAFDEC/AQD OJT Program; 5) Week-long 50th anniversary celebration; 6) 6 Aquaculture manuals unveiled in SEAFDEC/AQD's 30th book launching; 7) Filipinos, Thais train on marine fish hatchery; 8) Fish farmers, stakeholders gather for Farmer's Forum; 9) Training in marine fish hatchery organized for MAFAR-BARMM; 10) SEAFDEC/AQD at 37th PH Chemistry Congress in Bacolod; 11) More lab services accredited to meet international standard
Achieving high production of micropropagated seaweed through optimization of the culture protocol
No full textKappaphycus and Eucheuma are the two carrageenanproducing red algae extensively cultured and farmed in tropical and subtropical waters. Seaweed production accounted for 5.4 percent of the world’s aquaculture production in 2019, which was over USD 15 billion in value. With this value share, the production of seaweed farming was higher than other aquatic commodities, such as tilapia, carp, shrimps, and others (Cai et al., 2021). The red algae production of the Philippines started in the 1960s (Ronquillo & Gabral-Llana, 1989), and by the early 2000s, the country had become the world’s top supplier of seaweed, particularly Kappaphycus sp., until 2007, when Indonesia outperformed it.
Problems and challenges in seaweed farming, including climate change, pests and diseases, and biosecurity issues, caused the continuous decline of the seaweed production yield (Faisan, Sollesta-Pitogo, & de la Peña, 2022). Furthermore, the deterioration of seaweed quality caused by the repetitive use of vegetative cutting methods has also become one of the most pressing concerns in seaweed farming. Unfortunately, this procedure of growing plantlets for farming is one of the most common methods many seaweed farms used in the Philippines and other countries.
Research in SEAFDEC Aquaculture Department (AQD) looks into breaking from the conventional method of farming seaweed plantlets and optimizing laboratorybased production. With this, it hopes to create a more sustainable source of propagules, better growth and survival in grow-out, and a higher carrageenan quality in cultured Kappaphycus alvarezii
Nursery and grow-out culture of snubnose pompano (Trachinotus blochii, Lacepede) in brackishwater ponds
No full textThis manual, titled “Nursery and Grow-out Culture of Snubnose Pompano (Trachinotus blochii, Lacepede) in Brackishwater Ponds,” includes culture techniques and good practices developed through extensive research done at the Aquaculture Department of the Southeast Asian Fisheries Development Center. The manual also tackles a viable technology that can guide fish farmers in raising pompano in brackishwater ponds.This research is funded by SEAFDEC/AQD under the study code TV-05-F2021D
Lime application to condition soil to pH 11 controls growth of harmful vibrios and WSSV
No full textShrimp farming has been devastated by several diseases. Disease outbreaks can be prevented by optimising environmental conditions or by eliminating risks factors including carrier organisms. These can be achieved through proper pond preparation. One important step in pond preparation is the application of hydrated lime.
This paper describes the effect of hydrated lime application to condition pond soil to pH 11 on the pond ecosystem, more specifically on soil pH and biota. The experiment was done using three 600 m2 brackish water ponds. After hydrated lime application, the wet soil pH on the 1st-8th day was significantly higher (P<0.05) compared to the pH before liming to pH 11, and flushing after flooding for 24 h. Soil pH of 11 was observed 24-48h after lime application. Moreover, unwanted species like crabs and fish were found dead. Liming to pH 11 negatively affects the counts of green vibrio colonies thereby decreasing the percentage of green vibrios (PGV). In another experiment, three 750m2 earthen ponds were used. The pond soils were previously positive for the Whitespot Syndrome Virus (WSSV), hydrated lime were applied to bring the pond soil pH to 11. After lime application, WSSV was not detected in the pond soils.
Results showed that increasing the soil pH to ≥11 positively affects the pond ecosystem. Liming encourages the proliferation of yellow vibrios and the eradication of carrier species (i.e. crabs) as well as predators (i.e. fish) in the ponds. Furthermore, liming to pH 11 may also eradicate White spot virus from the pond sediment. To implement a 1-unit increase in wet pH, hydrated lime should be applied at 2T/ha.The study was funded by the Government of Japan (GoJ), under the trust fund awarded to SEAFDEC/AQD (study code: 8300-T-RD-FH0710)
Effect of diet isotopic ratios on the δ13C and δ15N signatures of scallop-gut contents in a natural setting
No full textThe relationship between diet isotopic signatures and the extent of the tissue-diet isotope fractionation factors have been shown previously in controlled feeding studies, but this relationship remains poorly resolved for marine invertebrates in a natural setting. Using isotope analysis of gut contents, this study investigated the variability in tissue-diet isotopic fractionation factors (Δδ13C and Δδ15N) between scallop tissues (i.e. muscle and digestive gland) and gut content in the Japanese scallop Mizuhopecten yessoensis (Jay, 1857) and assessed how the growth rate of juvenile scallops and gut content quality (as carbon to nitrogen (C/N) molar ratios) would affect the values of tissue-diet isotopic fractionation. Tissue-diet isotopic fractionation factors (Δδ13C and δ15N) varied according to tissue, which averaged 1.7‰ and −0.1‰ for N in muscle and digestive gland, and 3.4‰ and 1.2‰ for C in muscle and digestive gland, respectively. Muscle-gut δ15N isotopic factors negatively correlated with growth rate, suggesting that the juvenile δ15N signatures were strongly dependent on food quantity. The influence of diet quality on δ15N was also evident, where δ15N decreased as C/N molar ratios in gut contents increased. The wide difference in Δδ13C and δ15N from accepted standard values may be, in part, a consequence of using gut contents as a dietary proxy. Results of this study have implications for diet reconstruction studies of this scallop species reared under field conditions