Southeast Asian Fisheries Development Center
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Induction of moulting in hatchery-reared mangrove crab Scylla serrata juveniles through temperature manipulation or autotomy
No full textThe effects of temperature and autotomy of chelipeds on survival, growth and moulting of mangrove crab (Scylla serrata) juveniles were investigated under laboratory conditions for 60 days. Hatchery‐produced crabs with 2.0–2.3 cm internal carapace width (1.7–2.2 g body weight) at intermoult stage were exposed to one of four temperature treatments (constant 29, 32 or 35°C, or ambient [24–31°C]) or subjected to cheliped autotomy. All crabs held at 35°C had 100% mortality due to incomplete moulting during first moult. The mean survival of crabs at termination was 58%, 64% and 50% for ambient temperature, 29 and 32°C respectively. Specific growth rate (SGR) of crabs in the ambient and 29°C were comparable but significantly lower than those at 32°C. The moult interval of the crabs was significantly shorter in treatments with constant water temperature of 29 and 32°C compared with ambient temperature. The survival of crabs with intact chelipeds was comparable with those with one or two autotomized chelipeds. Crabs with intact or one autotomized chelipeds had significantly higher SGR than crabs with both chelipeds autotomized in the first moult. On the second moult, however, high SGR was observed in crabs with two chelipeds autotomized. The moult interval was significantly shorter in the autotomized crabs compared with crabs with intact chelipeds. The results suggest that the optimum water temperature for rearing S. serrata juveniles ranges from 29 to 32°C. Likewise, autotomy of chelipeds can promote moulting without adversely affecting survival of crabs
Aquaculture breeding enhancement: Maturation and spawning in sea cucumbers using a recombinant relaxin-like gonad-stimulating peptide
No full textThe Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fgene.2019.00077/full#supplementary-materialWild sea cucumber resources have been rapidly exhausted and therefore there is an urgent need to develop approaches that will help restocking. Currently, there is a lack of information regarding the genes involved in sea cucumber reproductive processes. The neurohormone relaxin-like gonad-stimulating peptide (RGP) has been identified as the active gonad-stimulating peptide in sea stars (Asteroidea), which could also be present in other echinoderm groups. In this study, a sea cucumber RGP was identified and confirmed by phylogenetic analysis. A recombinant Holothuria scabra RGP was produced in the yeast Pichia pastoris and confirmed by mass spectrometry. To assess bioactivity, four levels of purification were tested in an in vitro germinal vesicle breakdown (GVBD) bioassay. The most pure form induced 98.56 ± 1.19% GVBD in H. scabra and 89.57 ± 1.19% GVBD in Holothuria leucospilota. Cruder levels of purification still resulted in some GVBD. Upon single injection into female H. scabra, the recombinant RGP induced head waving behavior followed by spawning within 90–170 min. Spawned oocytes were fertilized successfully, larvae settled and developed into juveniles. Our results provide a key finding for the development of a break-through new artificial breeding approach in sea cucumber aquaculture
Emergency response to emerging disease: AHPND in shrimp
Get PDFOutbreaks of acute hepatopancreatic necrosis disease (AHPND) have caused great economic losses to many shrimp producing countries in Asia since its first appearance in 2009. The causative agent was first reported in 2013 as specific isolates of Vibrio parahaemolyticus (VPAHPND) that were later found to harbor a plasmid (pVA) encoding the Pir-like binary toxin genes PirvpA and PirvpB. More recent information indicates that pVA plasmid and variants occur in many Vibrio parahaemolyticus serotypes and also in other Vibrio species such as V. campbellii, V. harveyi and V. owensii. Information on such genomic and proteomic studies of different VPAHPND isolates from different countries are reviewed. A cohort study carried out in Thailand in 2014 indicated that AHPND outbreaks account for only a portion of the disease outbreaks reported by shrimp farmers as outbreaks of early mortality syndrome (EMS). It is urgent that the etiology of the other EMS-associated mortalities be investigated and not be overlooked. It is recommended that a regional research network and surveillance program for newly-emerging or re-emerging pathogens be established to speed up the process of diagnosis and the implementation of coordinated control measures and to avoid a repeat of the EMS/AHPND scenario
Induction of gonadal development in protogynous grouper with orally delivered FSH DNA
No full textThe availability of sexually mature fish often dictates the success of its captive breeding. In this study, we induced reproductive development in juvenile protogynous tiger grouper through oral administration of a plasmid (p) containing an engineered follicle-stimulating hormone (FSH). An expression construct (pcDNA3.1) was designed to express a single-chain FSH consisting of giant grouper FSH β-subunit and glycoprotein subunit-α (CGα), linked by the carboxy-terminal peptide (CTP) sequence from the human chorionic gonadotropin (hCG). Single oral delivery of pFSH encapsulated in liposome and chitosan to tiger grouper yielded a significant increase in plasma FSH protein level after 4 days. Weekly pFSH feeding of juvenile tiger groupers for 8 weeks stimulated ovarian development as indicated by a significant increase in oocyte diameter and progression of oocytes to cortical alveolar stage. As the pFSH treatment progressed from 20 to 38 weeks, female to male sex change was initiated, characterized by oocyte regression, proliferation of spermatogonial cells, and occurrence of spermatogenic cysts. It was also associated with significantly lower mRNA expression of steroidogenic genes (cyp11b, cyp19a1a, and foxl2) and basal plasma levels of sex steroid hormones 17β-estradiol (E2), testosterone (T), and 11-ketotestosterone (11KT). Results suggest that pFSH stimulates ovarian development up to cortical alveolar stage and then initiates sex change in tiger grouper. These findings significantly contribute to our knowledge on the role of FSH in the development of protogynous hermaphroditic fish. This study is the first to demonstrate induction of reproductive development in fish through oral delivery of plasmid gonadotropin.This research was supported by the Australian Centre for International Agricultural Research through Project No. FIS/2012/101 granted to Prof. A. Elizur (SEAFDEC/AQD Study code 6149-T-RDACIAR4). Mr. P. Palma was supported by John Allwright Fellowship, an ACIAR-funded Australia Awards
Feasibility of stock enhancement of tiger shrimp in Batan estuary in Philippines
No full textText in Japanese.Processes and results of stock enhancement of tiger shrimp performed in Batan Bay in Philippines was reported as a trans-disciplinary research for enhancement of area-capability (AC). Causes of decline in catch amount of tiger shrimp were overfishing and degradation of its nursery grounds such as mangrove forest. Five fishers had participated in the intermediate culture throughout the project period. Technical issues for stock enhancement were solved and expectable recapture rate of released shrimp was more than 20%. Economic feasibility of the stock enhancement was also confirmed. Forty-five percent of the people in the area are realizing the increase of catch amount of tiger shrimp. Effectiveness of stock enhancement is obtaining understanding from common people including public administrations. After the project, the stock enhancement was paused and stakeholders want to proceed with the stock enhancement. Aklan State University is planning to support stock enhancement project as its extension activities and expect participations of researchers from foreign countries. Such activities will provide research opportunities for evaluation and theorization of AC
Utilization of the tropical almond tree leaves in aquaculture
No full textTropical almond tree (Terminalia catappa), also known in the Philippines as “talisay” is a large tropical tree in the Combretaceae (leadwood tree) family that grows mainly in tropical areas of Asia. The tree grows from 10 m to 25 m high and has horizontal whorls of branches with shiny and ovate leaves, 10-25 cm long, and tapering below to a narrow and heart-shaped base with expanded rounded apex. “Talisay” fruit is smooth and ellipsoid, 3-6 cm long, and prominently bi-ridged or keeled down to the sides, with fibrous and fleshy pericarp and hard endocarp. Studies have indicated that the leaves of “talisay” are rich in tannins and a host of organic compounds that help in conditioning the culture water resulting in improved survival, growth, and health of cultured aquatic species
Responsible aquaculturists: The information-seeking behavior of milkfish farmers in Iloilo, Philippines
No full textCompliance 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
The information-seeking behavior of aquaculture researchers at the Southeast Asian Fisheries Development Center
No full textUnderstanding the information-seeking behavior of library patrons is essential for the library to provide quality resources and services, and to satisfy its patrons’ information needs. A quantitative research was conducted to describe the information searching and using behaviors of the Filipino aquaculture scientists, researchers and research staff at the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC/AQD). The study revealed that although the respondents find it useful to go to the library to get assistance from the librarian, and to browse and read current acquisitions related to their research, they visited the library infrequently. However, remote library services, especially email and phone services, were highly utilized. When searching for information, the Internet, mainly via search engines, was highly preferred rather than visiting the Library and using its online public access catalog (OPAC) or its databases. The combination of print and electronic formats was highly preferred when reading, rather than print only or electronic-only. The majority would print and save the retrieved electronic copy
Philippines: Aquatic emergency preparedness and response systems for transboundary diseases
Get PDFThe Bureau of Fisheries and Aquatic Resources (BFAR) of the Department of Agriculture as the Competent Authority, develops and implements rules and regulations on aquatic animal health for the Philippines. It establishes the monitoring system for OIE/NACA listed aquatic animal diseases. The disease surveillance and reporting activities are being carried out by the BFAR Fish Health Laboratory of the National Fisheries Laboratory Division and its counterparts at the regional offices. BFAR Fish Health Laboratories have different levels of diagnostic and detection capabilities for aquatic animal diseases. Diagnostic services and technical assistance are rendered to farmers on aquatic animal health. Results of diagnostic services and surveillance by BFAR central and regional offices, and other laboratories (SEAFDEC/AQD-Fish Health, DA-Biotech, Negros Prawn Cooperative) are part of the country s aquatic animal disease reports to the OIE/NACA. BFAR has a Fish Health Network that responds to aquatic animal disease emergencies. It also coordinates and collaborates through networking with research agencies, academe, private sectors and other stakeholders on aquatic animal health.
The Fisheries Inspection and Quarantine Division implements the policies on biosecurity, quarantine and health certification for trade and transboundary movement of aquatic animals. It is also responsible for risk analysis on the importation of fish and fishery/aquatic products. Other regulatory requirements for in-country movement include local transport permit for fish and fishery/aquatic products for traceability. Importers and exporters are also registered by BFAR to ensure compliance to sanitary and food safety measures and requirements. BFAR is continuously strengthening its technical capacity, human resources, policies and regulations for a more efficient implementation of aquatic animal health services that includes response to transboundary disease emergencies of aquatic animals