Southeast Asian Fisheries Development Center
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Resiliency of Gracilariopsis heteroclada (Zhang et. Xia) carpospores at different salinity and temperature levels
No full textEnvironmental factors like temperature and salinity play an important role in the growth and reproduction of aquatic organisms. The change in these two factors will be a major challenge in the future. Development of different culture techniques for Gracilariopsis heteroclada (Zhang et. Xia), a species usually found in the Philippines are being undertaken due to its increasing demand, however, there is a rapid depletion of natural populations. This study tested the resiliency of Gp. heteroclada to different water temperatures and salinities. Diploid spores from mature cystocarpic thalli of Gp. heteroclada were shed and grown at different temperatures and salinities under laboratory condition. Higher germination rate was obtained at 20°C (152.21 ± 69.88 carpospores) and 30°C (155.58 ± 66 carpospores) than at 40°C (7.56±6.54 carpospores) and 10°C (no spores were shed). Carpospores shed at 40°C degraded after 3 days. Growth rates of carpospores cultured on slides at 20 °C ranged from 2.37 to 5.92% day-1 while carpospores at 30°C ranged from 2.02 to 3.44% day-1. When carpospores were transferred to aerated vessels, growth rates decreased. At 20 °C, growth rates ranged from 0.84 to 2.96 % day-1 while at 30°C, growth rates ranged from 1.65 to 2.56 % day-1. Development rates had a wide range from 0.51 to 27.27% at 20 °C while at 30 °C, development rates ranged from 1.27 to 30 %. These results showed that Gp. heteroclada can shed carpospores at a range of 20-40 °C and 20-40 ppt. However, carpospores cannot fully develop at 40 °C. Optimum temperature for growth was at 20 °C and can grow at a wide range of salinity (20-40 ppt)
Addressing gaps in the culture of pathogen-free polychaetes as feed in shrimp hatcheries
No full textOne of the factors that contribute to the success of shrimp hatchery operations is the availability of good quality broodstock diets. Polychaetes have been regarded as the best maturation diet for shrimps as they contain essential nutrients requisite for the reproduction of shrimps. Consequently, the demand for polychaetes increased with the intensification of shrimp farming and as a result, the natural stocks are depleting gradually and thus, could no longer provide sustainable supply for shrimp hatcheries. In addition, the issue on biosecurity concerning wild polychaetes prompted the shrimp farmers to obtain polychaetes from reputable sources, thus, the culture of polychaetes under controlled condition has become a sustainable alternative. The SEAFDEC Aquaculture Department (SEAFDEC/AQD) therefore initiated the “Refinement of rearing and feeding techniques for sustainable mass production of the polychaete Marphysa sp.” to address the gaps in polychaetes culture and ensure the sustainability of polychaetes production to supply the shrimp hatcheries at SEAFDEC/AQD, and where the potential mass production of the polychaetes (Marphysa sp.) in indoor tanks is being undertaken to ensure that these are pathogen-free
Tigbauan Main Station
Get PDFEstablished in 1973, the Tigbauan Main Station (TMS) is the SEAFDEC/ AQD headquarters located on the south coast of Panay Island. The 40-hectare complex includes various research laboratories, hatcheries, and broodstock facilities for experiments in artificial propagation, feed development, and health management. TMS also has training facilities, a library, and a medical clinic. On-campus housing and cafeteria cater to resident staff, trainees, guests, and visiting researchers and their families
Limit of colour vision in dim light in larvae of the giant freshwater prawn Macrobrachium rosenbergii
No full textColour 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
Does age matter?: The information-seeking behavior of Filipino aquaculture researchers
No full textFindings 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
Larval rearing of mud crab (Scylla): What lies ahead
No full textThe 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
Parasites from the green mussel (Perna viridis Linnaeus 1758) (Mollusca: Mytilidae) of Ivisan, Capiz, Philippines
No full textThis 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
Promoting responsible aquaculture for the sustainable production of soft-shell crabs
No full textSoft-shell crabs command a high price because these could be eaten whole when cooked. Myanmar, Viet Nam, and Thailand are among the Southeast Asian countries that produce considerable quantities of soft-shell crabs mostly sold to local restaurants as well as exported to Australia, Europe, Hong Kong, Japan, Singapore, South Korea, Taiwan, and the USA. Production of soft-shell crabs is an emerging technology in the Philippines, where the demand for this product has been increasing and the technology becoming a growing interest. With prices that could range from US 15 US$ or higher per kilogram depending on the size, soft-shell crabs are bought in bulk by elite restaurants in the Philippines that usually serve this delicacy with complimentary food or drinks. Although the demand for soft-shell crabs is high, production is still unstable due to lack of seedstocks, which are mainly sourced from the wild. To reduce the pressure on the natural population, SEAFDEC/AQD has initiated the development of soft-shell crab technology using hatchery-produced seedstocks, and is currently promoting the use of hatchery-produced seedstocks for soft-shell crab farming to local and international stakeholders all over the Southeast Asian region through its training courses. With funding support from the Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development (PCAARRD) of the Department of Science and Technology (DOST) through its National Mud Crab Science and Technology Program (NMCSTP), SEAFDEC/AQD has intensified the development of the soft-shell crab technology. Applicable to all mangrove (mud) crab species, the technology for the production of soft-shell crabs could now be pursued using hatchery-produced seedstocks is described in this article
Preliminary findings on supplementation of snapper fry, Lutjanus sp. with DHA-rich thraustochytrid strain, Schizochytrium sp. LEY7 showed increased growth, survival and robustness
No full textIn this study, a preliminary experiment was conducted to investigate the beneficial effects of an indigenous DHA-rich thraustochytrid strain, Schizochytrium sp. LEY7 as supplement for snapper fry Lutjanus sp. using a long-term enrichment method (24 h) via Artemia. Results on the average total length (ATL) indicated that Schizohchytrium sp. LEY7 can be used as a growth enhancer (3.07 ± 0.03 mm) over the hatchery-produced emulsion (2.87 ± 0.04 mm) and the commercial enrichment SELCO (2.91 ± 0.04 mm). Starved treatment has an ATL of 2.89 ± 0.03 at the end of the feeding trial. Highest survival was obtained in the treatment fed Schizochytrium-enriched Artemia, with a mean survival of 65.52 ± 4.83, as compared to treatments fed Artemia enriched either with hatchery-produced emulsion (30.69 ± 25.17) or SELCO (54.14 ± 4.48). Survival of the starved treatment was 27.93 ± 10.69. There was a trend of lowest mortality seen for the treatment fed Schizochytrium-enriched Artemia when immersed at different salinity levels. Treatment fed SELCO-enriched Artemia was infested with the parasitic dinoflagellate Amyloodinium sp. Overall, the preliminary data obtained from this study indicate that the supplementation of Schizochytrium sp. LEY7 increases the quality of snapper fry and its chance of survival under adverse environmental conditions. Confirmatory experiments are therefore suggested to verify the results obtained