Southeast Asian Fisheries Development Center
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Antioxidant activities and selenogene transcription in the European sea bass (Dicentrarchus labrax) liver depend, in a non-linear manner, on the Se/Hg molar ratio of the feeds
Get PDFFeeding 3.9 and 6.7 mg Hg/kg (Se/Hg molar ratios of 0.8 and 0.4, respectively) for 14 days negatively affected Dicentrarchus labrax growth and total DNTB- and thioredoxin-reductase (TrxR) activities and the transcription of four redox genes (txn1, gpx1, txnrd3, and txnrd2) in the liver, but a diet with 0.5 mg Hg/kg (Se/Hg molar ratio 6.6) slightly increased both reductase activities and the transcription of txn1, gpx1, and txnrd2. Feeding 6.7 mg Hg/kg for 53 days downregulated the genes of the thioredoxin system (txn1, txnrd3, and txnrd2) but upregulated gpx1, confirming the previously proposed complementarity among the antioxidant systems. Substitution of 20% of the feed by thawed white fish (hake) slightly counteracted the negative effects of Hg. The effects were not statistically significant and were dependent, in a non-linear manner, on the Se/Hg molar ratio of the feed but not on its Hg concentration. These results stress the need to consider the Se/Hg molar ratio of the feed/food when evaluating the toxicity of Hg.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. The work was supported by grants from the Spanish MINECO (RTC-2014–2837-2- “SELATUN: Minimización de la problemática del mercurio del atún y valorización del atún como alimento saludable, Programa Retos-Colaboración 2014” and CTM2012-40203-C02-01- “BMW: Biomarcadores estándar de base científica en mejillón para diagnosticar y monitorizar los efectos biológicos de la polución en el Golfo de Bizkaia: implementación de la DEME”), Euskampus Fundazioa-Campus of International Excellence (307615SAA2), and from the Basque Government Elkartek Grant KK-2016/00057- “MAROMEGA: Nuevas alternativas para la producción de omega-3 a partir de recursos marinos.
Evaluation of community-based livelihood development initiatives: The sustainable livelihood approach
No full textThe sustainable livelihood approach (SLA) is a tool for evaluating livelihood strategies that utilize assets categorized as environmental, human, physical, financial and social assets. In this study, the SLA was applied to determine the main factors that influence the adoption of integrated multi-trophic aquaculture (IMTA) in milkfish (Chanos chanos Forsskål) farming among fisherfolks. The community-based field trials conducted in Nueva Valencia in Guimaras province for 4 years since 2015 revealed that stakeholders were receptive to IMTA and were able to situate its effects on livelihood assets. The assessment of 52 stakeholders showed small but significant improvements in most livelihood assets during the 3-phased evaluation period. Using the 5-scale Likert rating, the environmental livelihood assets were rated highest but showed slight significant decline due to perceived weather and water level changes that may have negatively affected fish production and income. Financial livelihood assets were initially rated low but significantly improved due to supplemental income derived from wages and harvest. The human livelihood assets significantly improved due to sustained hands-on aquaculture experience. Social livelihood assets also improved due to cohesive interaction during projects implementation. In contrast, the acquisition of physical livelihood assets did not significantly improve because these assets were not commensurate with the many stakeholders who would like to have access to these shared assets. Overall, stakeholders expect IMTA’s potential environmental and economic benefits to overcome additional adoption costs. These include the cost of physical and financial investments in seeds of co-culture species and modified enclosures. Stakeholders expect institutional and government support on further studies on the technical details of IMTA. Fisheries and aquaculture regulations should embed the necessary support systems for the adoption of IMTA and ensure a positive public perception of aquaculture
Environmental impact and growth performance of IMTA species in marine pen culture system
Get PDFIn this study, locally available marine species were tested, milkfish (Chanos chanos) as the fed species, seaweed (Kappaphycus alvarezii) as inorganic-extractive species for the water column, and sandfish (Holothuria scabra) as organic-extractive species on the sediments. This study aims to verify and improve IMTA systems suitable for farm conditions in coastal areas in the Philippines, with emphasis on mitigating the environmental impacts of mariculture of milkfish
Evaluation of maturation promoting factor in polychaete (Marphysa sp.) on Indian white prawn, Penaeus indicus female broodstock
No full textPolychaete is considered the best maturation diet for penaeids; however, fluctuating supply and quality warrant detailed studies to understand the specific maturation-promoting factors present in polychaete. Indian white prawn, Penaeus indicus, was fed diets supplemented with different fractions of Marphysa sp. extracts. Fractions, such as the total soluble fraction (TSF), neutral lipid fraction (NLF), and polar lipid fraction (PLF), were incorporated in the maturation diet at 0.25, 0.50, and 1.00% following a 3 × 3 factorial design. One group was fed with basal diet (BD), and another was fed with fresh squid, mussel, and polychaete, serving as the control. After a 30-day feeding trial, results showed that the inclusion of polychaete extracts in the diet significantly improved P. indicus maturation compared to groups fed BD and control with 40% maturation rates (MR) (p = 3.4 × 10−4). MR was optimum in groups receiving diets supplemented with ≥0.5% TSF (70.00% ± 0.00) and NLF (60.00% ± 5.77). Similar improved MR was achieved in treatments receiving ≥0.25% PLF supplementation (60% ± 0.00). Accordingly, relative expression of ovarian vitellogenin mRNA of broodstock fed under 0.25 and 0.50% PLF group was 4.44 and 3.96 folds higher than BD, respectively (p = 0.003). No significant differences were detected in the broodstock survival, latency period, hepatosomatic, and gonadosomatic indices. Biochemical content analyses showed no significant differences among the nine treatments except for broodstock's higher ovary protein content in the TSF group (p = 0.037). This study highlights PLF as the most potent component of the polychaete extract in promoting gonad maturation in P. indicus maturation supplemented at a 0.25% optimum inclusion level.Department of Science and Technology-Accelerated Science and Technology Human Resource Development Program, Student Research Support Fund; Southeast Asian Fisheries Development Center/Aquaculture Department, Grant/Award Number: FD-02-C2019
Evaluation of livelihood assets in community-based on-farm demonstration of IMTA in milkfish mariculture in Guimaras, Philippines
Get PDFThis study showed the need to develop the livelihood assets of rural communities to enable them to engage in aquaculture-based income generating activities. The SLA evaluation showed that the benefits in terms of its contribution to livelihood asset build-up is generally positive. While human, social and environmental capacities were improved, the financial and physical assets were dissipated and insufficient for many stakeholders with keen interest to participate in the communal project. Therefore, the recommendation is to organize more and bigger collaborative projects, such as this IMTA of milkfish, with emphasis on sustainable livelihood asset development to create significant economic impact to target beneficiaries
Use of rotifers-fed microalgal paste in the seed production of mangrove crab Scylla serrata in the Philippines
No full textDespite the progress in the production of artificial diets for marine larvae, feeding during the early life stages of most aquaculture species still relies on live feeds such as rotifers. Advanced rotifer culture techniques are also available, however, in the Philippines, majority use batch cultures with fresh microalgae. These microalgae are prone to collapse resulting to inadequate supply of food for the rotifers that are fed to the larvae. Mangrove crab is one of the economically important aquaculture species in the country where mass seed production requires sufficient and steady supply of rotifers. Thus, here we examined the possibility of substituting fresh culture of green microalgae Tetraselmis tetrathele (FA) with flocculated T. tetrathele paste (FP) and commercially available Tetraselmis sp. (CP) as feed for rotifers (Brachionus rotundiformis) in the seed production of mangrove crab. Rearing of larvae was done until crab instar 1 (DOC 24) where growth and survival were taken to evaluate the viability of rotifers-fed microalgal paste. It was observed that the growth index (FA–6.93 ± 0.07; FP–6.91 ± 0.07; CP–6.96 ± 0.05) was similar for all treatments (P > 0.05) at termination. Comparable survival rates were noted for FA and FP at 1.08 ± 0.59% and 3.21 ± 2.09%, respectively (P > 0.05) while a significantly higher survival (P < 0.05) was recorded for CP at 7.73 ± 1.90%. These findings suggest that the algal paste tested are potential alternatives to fresh microalgae and this technique could benefit hatchery operators who lack the capital for setting up the facility and technical skills to maintain microalgae production.This research project was carried out with the support of SEAFDEC/AQD (study code NR-02-C2018T). The authors greatly appreciate the assistance of Phycology laboratory and Crab hatchery staff in the production of algae and rotifers, and in the larval rearing experiments, respectively
Accumulation and depletion of oxytetracycline (OTC) and oxolinic acid (OXA) in Pompano, Trachinotus blochii
No full textAccumulation and depletion including withdrawal period for oxytetracycline (OTC) and oxolinic acid (OXA) in pompano (Trachinotus blochii) were determined following oral administration. Pompano were cultured in 250-L fiberglass tanks in a flow-through system provided with aeration. Observed average temperature was 30°C; salinity was 30 ppt. Fish were starved for 2 days then fed with OTC medicated diet (75mg/kg fish/day) or OXA medicated diet (30 mg/kg fish/day) 3 times a day for 10 successive days at 2% body weight and thereafter switched to regular diet for 45 days. Muscle and blood samples were taken at regular intervals during and after cessation of medication. OTC residues in the muscle and blood were analysed using the high performance liquid chromatography (HPLC). Peak OTC accumulation was observed at day 10 of treatment. Higher OTC accumulation was observed in the muscle (0.88+0.27 µg/g) than in the blood (0.3+0.09 µg/ml). OXA accumulation peaked on day 5 of treatment; higher OXA accumulation was observed in the muscle (0.11+0.06 µg/g) compared to blood (0.005+0.0001 ug/ml). Withdrawal period at 30°C for OTC in pompano muscle was 19 days (570 degree-days) and 17 days (510 degree-days) in the blood. For OXA, the withdrawal period in pompano muscle and blood at 30°C temperature was 3 days (90 degree-days).The study was funded by the Government of Japan under the Trust Fund (GoJ TF 4) granted to SEAFDEC AQD under study code FH-01-F2014T
Grouper - Code of good aquaculture practices (GAqP)
No full textSince 2014, the Bureau of Agriculture and Fisheries Standards-Department of Agriculture (BAFS-DA) has developed various Philippine National Standards (PNS) on the Code of Good Aquaculture Practices (GAqP) specific for finfish, crustaceans, molluscs, and aquatic plants. In 2020, the Southeast Asian Fisheries Development Center (SEAFDEC) requested for a specific PNS on GAqP for grouper considering grouper’s high demand and market potentials. In 2021, BAFS commenced the development of this PNS which aims to set recommended minimum requirements that will help the farmers to have a common understanding on the production practices in rearing groupers. In addition, this standard will also help in achieving the desired safety and quality parameters set out in PNS/BAFS 73:2021 (Live, chilled, or frozen grouper).
The Technical Working Group (TWG) tasked to develop the PNS was created through Special Order (SO) No. 103, series of 2022 (Creation of TWG for the Development of PNS for Agriculture and Fishery Products, Machinery, Tools, and Equipment). The TWG was composed of representatives from the relevant government agencies, academe/research institution, private sector, and Civil Society Organization (CSO). The draft PNS underwent a series of TWG meetings and stakeholder consultations conducted physically and via online platforms before its endorsement to the DA Secretary for approval.
This document was drafted in accordance with the editorial rules of the BAFS Standards Development Division Standardization Guide No. 1: Writing the Philippine National Standards
Influence of water temperature on induced reproduction of milkfish during the off-season
No full textScientific studies on milkfish’s induced spawning and larval rearing by increasing water temperature in tanks are very limited. In order to increase the production capacity of milkfish fingerlings, a preliminary experiment was conducted at the Southeast Asian Fisheries Development Center, Aquaculture Department (SEAFDEC/AQD). This study was on the effect of increased water temperature in milkfish broodstock and larval tanks during the cold and off-breeding season (October to February)