Research on crustaceans
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Crustacean research at the SEAFDEC Aquaculture Department in 1994-1999 focused on two commercially important species: the tiger shrimp Penaeus monodon, and the mud crab Scylla serrata. Research on tiger shrimp dealt with broodstock development, refinement of shrimp culture systems, and health management. Broodstock development aimed to develop a technology for a sustainable supply of good quality captive broodstock through selective breeding. Initial efforts identified polymorphic stocks with low disease prevalence as base population and development of screening protocol to assess their health status using non-lethal procedures. Improvement of reproductive performance through studies on nutritional requirements and sperm quality was also conducted. To refine shrimp culture systems, emphasis was placed on the physiological requirements of tiger shrimp, including salinity adaptation and osmoregulatory capabilities, improvement of formulated diets, and development of culture systems that are compatible with the environment. In shrimp health management, disease problems in various culture systems with emphasis on luminescent vibriosis and some viruses were defined. The quality of hatchery-reared post-larvae compared with those caught in the wild was assessed. Research on the mud crab Scylla serrata started late in 1996. Studies were conducted on all culture phases: broodstock, hatchery, nursery, and grow-out. Broodstock development emphasized the development of an appropriate maturation system and a suitable maturation diet. The influence of eyestalk ablation and dietary history on reproductive performance was assessed. The completion of the mud crab life cycle in captivity was attained in 1997 when spawns from pond-reared females were further reared to produce second-generation broodstock. In the hatchery, larval rearing based on previous trials on feeding schemes, salinity tolerance, and water conditioning hastened progress in larviculture and formed the basis for large-scale production of mud crab juveniles. Research has shown the feasibility of direct stocking of crab megalopae in hapa nets in nursery ponds. In grow-out culture, studies have been done on the effects of stocking density, monosex culture, and practical diet development for the mud crab. Practical diets, formulated using local materials as ingredients, with or without vitamin and mineral supplementation, were found to be economically feasible for mud crab culture in ponds. Grow-out culture in mangrove pens appears to be an environment-friendly alternative to the usual open pond culture system.
Millamena, O. M. (2001). Research on crustaceans. In L. M. B. Garcia (Ed.), Responsible Aquaculture Development in Southeast Asia. Proceedings of the Seminar-Workshop on Aquaculture Development in Southeast Asia organized by the Aquaculture Department, Southeast Asian Fisheries Development Center, 12-14 October 1999, Iloilo City, Philippines (pp. 199–207). Tigbauan, Iloilo, Philippines: Aquaculture Department, Southeast Asian Fisheries Development Center. http://hdl.handle.net/10862/472
PublisherAquaculture Department, 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 The 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.
Conference paperM Chaengkij - In JH Primavera, ET Quinitio & MR Eguia (Eds.), Proceedings of the Regional Technical Consultation on Stock Enhancement for Threatened Species of International Concern, Iloilo City, Philippines, 13-15 July 2005, 2006 - Aquaculture Department, Southeast Asian Fisheries Development CenterThe paper provides a comprehensive list of endangered freshwater, brackishwater, and marine aquatic species in Thailand. The Thai Department of Fisheries is breeding some of the endangered species under the “Rehabilitation of Thai Local Fishes and Aquatic Animals Project.” Some of these species are bred for restocking in the wild.
Conference paperNA Lopez - In JH Primavera, ET Quinitio & MR Eguia (Eds.), Proceedings of the Regional Technical Consultation on Stock Enhancement for Threatened Species of International Concern, Iloilo City, Philippines, 13-15 July 2005, 2006 - Aquaculture Department, Southeast Asian Fisheries Development CenterThe paper provides the lists of fisheries related species perceived to be extinct, rare, threatened and endangered as covered under the CITES, IUCN and the Bureau of Fisheries and Aquatic Resources (BFAR)-Fisheries Administrative Order (FAO) No. 208. The listings of freshwater fisheries resources constitute mostly finfishes that are all, except for one, found in the CITES list, the rest under the IUCN red lists and none in the BFAR list. Majority of the listed species are also specific to some areas like Lanao Lake, few in the RINCONADA lakes of Bicol and scarce in some other minor lakes where they are found to be endemic. Most of the indigenous cyprinid species are of commercial value to the locality and are the main source of fish protein in the daily life of the fisherfolk. The listings of marine finfishes constitute mostly sharks and seahorses which are all, except for one, found in the CITES list, the rest under the IUCN Red List and none in the BFAR-FAO list. Although BFAR listed 20 species of whales and dolphins under its FAO 208, marine mammals are not included in this report. Most of the indigenous shark species are becoming rare and extinct due to the rampant shark Status of Threatened Species and Stock Enhancement Activities in the Philippine Fisheries with the rising demand of shark fins smuggled or exported abroad. These marine finfishes are distributed in coastal waters. The listings of marine gastropods, mollusks, crustaceans and echinoderms are all found in the BFAR-FAO listings as Rare, Threatened and Endangered, while few and selective under the CITES and IUCN lists. Accordingly, these are the most common marine resource commodities that are over-exploited, gleaned and gathered illegally, and frequently exported or smuggled out of the country by unscrupulous traders.