Southeast Asian Fisheries Development Center
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Morphological descriptions and morphometric discriminant function analysis reveal an additional four groups of Scylla spp
No full textThere are four species of mud crabs within the genus Scylla, and most of them live sympatrically in the equatorial region. Apart from a report in Japan about the finding of a natural Scylla hybrid more than a decade ago after the division of genus Scylla into four species by Keenan, Davie & Mann (1998), no subsequent sighting was found. Thus, this study investigates the possible natural occurrence of potential hybridization among Scylla species in the wild. A total of 76,211 individuals from mud crab landing sites around the Malacca Straits, South China Sea and Sulu Sea were screened. In addition to the four-purebred species, four groups (SH 1, n = 2, 627; SH 2, n = 136; SH 3, n = 1; SH 4, n = 2) with intermediate characteristics were found, mostly at Sulu Sea. Discriminant Function Analysis revealed that all Scylla species, including SH 1 - 4, are distinguishable via their morphometric ratios. The most powerful discriminant ratios for each character and the top five discriminant ratios of males and females were suggested. The carapace width of SH 1 males and females were significantly smaller than pure species. Based on the discriminant ratios and the description of morphological characters, we hypothesize that the additional four groups of Scylla with intermediate characteristics could be presumed hybrids. Future work at the molecular level is urgently needed to validate this postulate
Efficacy of poultry by-product meal as an effective alternative to fish meal in aquaculture feed for milkfish Chanos chanos
No full textWe verified the efficiency of poultry by-product meal (PBM) as a substitute for fish meal (FM) in feed for juvenile milkfish (Chanos chanos). Juveniles (mean 48.0 g) were fed for 12 weeks with two experimental feeds containing different levels of PBM (8.0% and 12%), FM (10% and 5.0%), and cod liver oil (fish oil or FO, 4.0% and 3.8%). A feed without PBM having higher levels of FM and FO (20% and 4.5%, respectively) was used as control. Weight gain, specific growth rate, and feed conversion ratio were not significantly affected by the levels of dietary PBM. In addition, no significant differences were detected among the dietary groups in plasma triglyceride, total cholesterol, phospholipid, glucose, or total protein concentrations. Furthermore, crude protein, crude fat, moisture, and ash contents in the whole body, liver, and dorsal muscle were not significantly influenced by the dietary treatments. The results of organoleptic examinations that included tests of smell, flavor, and texture were almost the same among the dietary groups. These results indicated that PBM is the applicable substitute for FM, with performance of the high PBM feed (PBM-FM-FO = 12%-5.0%-3.8%) being comparable to that of the control feed.This study was conducted as part of the international research project “Development of Technologies for Sustainable Aquatic Production in Harmony with Tropical Ecosystems” of the Aquaculture Department of the Southeast Asian Fisher ies Development Center (SEAFDEC/AQD) and the Japan International Research Center for Agricultural Sciences (JIRCAS). The study was funded in part by the Fisheries Agency, Ministry of Agriculture, Forestry and Fisheries, Government of Japan. The authors gratefully acknowledge Dr. R. E. P. Mamauag of SEAFDEC/AQD for his valuable advice. In addition, the authors would like to thank Editage (www.editage.jp) for English language editing
Microbial diversity assessment in milkfish culture ponds
No full textAims: To determine bacterial diversity in milkfish culture ponds that contain different life-cycle stages of the milkfish (pond A: fry, pond B: juveniles and pond C: adults) by DNA sequence analysis of organisms and compare that microbial diversity to organisms found in soil adjacent to the ponds.
Study Design: Comparative metagenomic study of aquatic and terrestrial biodiversity based on DNA sequence analysis of water and soil DNA.
Place and Duration of Study: SEADEC milkfish ponds in Tigbauan, Iloilo, Philippines. All water and soil samples were collected over a three-day period.
Methodology: DNA sequence analysis of nucleic acids extracted from water samples collected from the three types of milkfish ponds along with soil adjacent to the ponds. DNA was extracted and PCR was performed using the 11F-1492R primer pair to amplify 16S rRNA gene. Purified 16S rDNA amplicons were cloned in using the TOPO-TA cloning kit for DNA sequencing. 16s rRNA gene sequences were analyzed with the use of software tools at the National Center for Biotechnology Information website and imported into the ARB phylogenetic analysis software. Distance matrices were exported using the neighbor-joining algorithm in ARB, in the form of PHYLIP-formatted lower triangular matrices. The distance matrices were then used to calculate Shannon-Weaver and Simpson diversity indices to evaluate the richness and evenness of the sampled populations. Rarefaction curves were determined to evaluate sampling efficiency.
Results: Rarefaction curves indicated that the sampling effort was sufficient to reveal the majority of phyla present in the sample. Shannon-Weaver and Simpson indices suggested that the diversities of all the groups were statistically different from each other. It was observed that pond A was least diverse, followed by pond C and pond B. The soil was most diverse. DNA sequence analysis identified the various species of bacteria in soil and water.
Conclusion: All three pond communities were significantly different in diversity. This study did not identify any significant human pathogens such as Vibrios, Salmonella or Shigella. Bacterial diversity of sites decreased in the following order: soil > fry pond > fingerling pond > adult pond
Survival, growth and biomass of mud polychaete Marphysa iloiloensis (Annelida: Eunicidae) under different culture techniques
No full textPolychaetes are commercially exploited as fishing bait and supplemental diet to crustacean and finfish broodstock. However, scarcity of supply and biosecurity issues limits its use. Polychaete aquaculture has become the best alternative to wild resources. In this study, two different culture techniques (1‐sediment tank throughout the culture period and 2‐nursery tank with bioflocs for 30 days; thereafter, juveniles were transferred to sediment tank until harvest) using two diets [bioflocs (BF) and feed mill sweepings (FS)] were tested to determine the survival, growth and biomass of polychaete Marphysa iloiloensis (Glasby et al., Zootaxa, 2019, 4674) in the grow‐out. The 180‐day trial was conducted in 16 tanks (0.20 m2) stocked with 5,066 ± 575 M. iloiloensis trochophore larvae/tank which were assigned randomly into four culture treatments with four replicates each. The treatments were labelled as: (a) BFS – fed BF in sediment tank for 180 days; (b) BF + BFS – fed BF in nursery tank for 30 days, juveniles were transferred in sediment tank and fed BF for another 150 days; (c) FSS – fed FS in sediment tank for 180 days; and (d) BF + FSS – fed BF in nursery tank for 30 days, juveniles are transferred in sediment tank and fed FS for another 150 days. Results showed that polychaetes in BF + FSS had significantly higher survival than BFS. Polychaetes in both BF + FSS and FSS had significantly higher body weight than BF + BFS and BFS, while biomass in BF + FSS (175.73 ± 42.25 g/tank) was significantly higher compared to other treatments (p < .05). Polychaetes fed with FS had 61%–64% protein and 12%–13% fat, while those fed with BF exclusively had 66%–70% protein and 3.50%–4.50% fat. The findings indicate that FS whether or not BF is included in the diet can improve both survival and growth of polychaetes but significantly higher biomass can be achieved with the combination of BF and FS. Additionally, polychaetes in BF + FSS contained 64% protein and 13% fat. Therefore, BF can be used as an alternative diet to FS in the early life stages of M. iloiloensis and nursery rearing using BF is imperative to increase its biomass in the grow‐out production.This study was funded by the Aquaculture Department, Southeast Asian Fisheries Development Center (SEAFDEC/AQD) under the study code Br-02-Y2016T
Immune response of Litopenaeus vannamei juveniles immersed in Gracilariopsis heteroclada hot-water extract
No full textThe emergence of diseases such as Acute Hepatopancreatic Necrosis Disease and White Spot Syndrome has compelled researchers in shrimp aquaculture to develop more innovative methods in improving shrimp health management for the prevention of diseases. One of these methods involves the use of immunostimulants, which enhance the innate immunity of shrimp. Polysaccharides extracted from red seaweeds such as Gracilariopsis heteroclada, locally known as “Gulaman”, present a great source of immunostimulants. Thus, this study aimed to evaluate Gracilariopsis heteroclada as an immunostimulant for Litopenaeus vannamei, or Pacific white shrimp. Hot-water extracts of Gracilariopsis heteroclada were administered through immersion. Results showed no significant changes in total haemocyte count, ambiguous fluctuations in phenoloxidase activity, and a late temporary increase in respiratory burst activity. Overall, these indicate a lack of significant immunostimulation in Litopenaeus vannamei juveniles when immersed in Gracilariopsis heteroclada hot-water extract
Emergency preparedness and response systems for aquatic animal diseases in Malaysia
Get PDFThe Department of Fisheries (DoF) Malaysia is the custodian of the Fisheries Act 1985, which serves as the main legislative source for subsidiary regulations, including aquaculture and fish health management. It has established Emergency Disease Task Force Committee for any emergency related to disease outbreak as well as standard operating procedures for massive fish kill. This committee consists of taskforce teams from federal and/or state fisheries and oversee the operations of the task force. Fisheries Biosecurity Division under DoF Malaysia holds the primary responsibility for managing the country s emergency preparedness and response system for aquatic animal diseases. As for early detection system, Fisheries Biosecurity Division has established official control and official analysis for targeted diseases listed under OIE and National Listed Diseases. Fish health monitoring programmes are conducted every six months and samples are analyzed by accredited laboratories. Quarterly and half year reports are submitted to representative offices for the health status of targeted disease. Apart from the targeted fish health monitoring program, epidemiology on common and emerging diseases are conducted by National Fish Health Research Division (NaFisH) which is the only research and development arm under DoF. Laboratories under Fisheries Biosecurity Division are responsible for organizing and coordinating surveillance programs for diseases in the OIE list while NaFisH is responsible for conducting research and development on aquatic diseases that cause high losses in industry since 2002. Currently, the DoF has four servicing laboratories under Fisheries Biosecurity Division and one NaFisH laboratory under Fisheries Research Institute for fish health diagnosis in Malaysia
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
No full textThis 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% (FTBM12.5), 25.0% (FTBM25), 37.5% (FTBM37.5), or 50% (FTBM50). After 8 wk, weight gain, specific growth rate, and feed efficiency of fish fed FTBM0 and FTBM12.5 diets were significantly higher than fish fed the other diets (P 0 and FTBM12.5 diets were significantly higher than those fed FTBM50 diet at Day 9 postchallenge with Edwardsiella tarda (P 0 and FTBM12.5 diets was significantly higher (P 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
Fish disease control in Japan
Get PDFThe regulatory authority responsible for the control of aquatic animal diseases in Japan is the Animal Products Safety Division, Food Safety and Consumer Affairs Bureau, Ministry of Agriculture, Forestry, and Fisheries (MAFF). The ministry (Animal Products Safety Division) specifies certain diseases and their host species that are subjects for import quarantine on the basis of the law called Fisheries Resources Protection Act. The MAFF also implements risk control measures for the same diseases within Japan on the basis of another law, Fish Farming Production Maintaining Act. Currently, 24 such diseases are listed. For disease control within Japan, the MAFF issues Guideline for the Control of Aquatic Animal Diseases, which states the roles of different stakeholders, appropriate actions that are to be taken on the occurrences of specified or other diseases, fish health guidelines for fish farmers, or diagnostic methods for specified diseases, etc. Local prefectural governments in Japan are required to place personnel who work on fish health issues at the prefectural fisheries research laboratories. These people usually inspect fish farms, observe cultured aquatic animals, supervise the use of antibiotics or vaccines, and guide fish farmers for disease control. Disease diagnosis for aquatic animals is usually conducted by these local fisheries research labs for free. The Japan Fisheries Resource Conservation Association provides a comprehensive training course on fish diseases including laws or hands-on trainings for the staff of prefectural fisheries research laboratories. The JFRCA also give local fish health personnel the qualification as the fish health expert, if the person passes the examination conducted after the training course. Primary diagnosis for specified diseases is conducted by local fisheries laboratories. On the occurrence of the diseases that are suspected to be one of the specified diseases or OIE listed diseases that have not been reported in Japan, the samples are sent to the National Research Institute of Aquaculture (NRIA) where confirmatory diagnosis is made. When such diseases are confirmed, it is reported to the MAFF (or to the OIE through MAFF). For specified diseases, Fish Farming Production Maintaining Act enables local governments to implement necessary measures to prevent the disease from spreading, including issuing orders such as to stop the transfer of the animals to other watersheds, to destroy animals, or to disinfect the facilities. When an unknown disease is encountered by a prefectural fisheries research laboratory, the NRIA is requested to conduct diagnosis. The NRIA develops diagnostic methods for new diseases and disseminate the techniques to local fisheries research laboratories. The NRIA provide positive control materials for disease diagnosis, hands-on trainings of specific subjects concerning diagnostic techniques, or proficiency tests for the fish health personnel of the local fisheries research laboratories