Now showing items 1-3 of 3

    • Conference paper

      Development of protocol for the production of hatchery-reared mud crab Scylla serrata juveniles for soft-shell crab farming 

      ET Quinitio, GX Libunao & FD Parado-Estepa - In ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.), Philippines : In the forefront of the mud crab industry development : proceedings of the 1st National Mud Crab Congress, 16-18 November 2015, Iloilo City, Philippines, 2017 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Development of economically viable techniques for growing hatchery-reared juvenile crabs to suitable sizes will address the problem on the source of seed stocks for soft-shell crab farming. This paper reports the production of hatchery-reared mud crab Scylla serrata from juveniles in the nursery to 73-106 g body weight (BW) crabs in the grow-out pond for the individual system soft-shell crab farming. Likewise, the performance of hatchery-reared S. serrata, and wild S. tranquebarica and S. olivacea juveniles was determined in the soft-shell crab production set-up.

      The BW increased from 1.8-1.9 g to 78-113.7 g when stocked at 0.5 ind m-2 and from 1.6-2.3 g to 73-106.7 g at 1.0 ind m-2 after 75 days. Growth rates at both stocking densities were comparable. However, survival was significantly higher (P<0.05) in lower (63.6~c1.01%) than in higher (35.6~c3.34%) stocking density. Male S. serrata (46.0 ~c 1.75%) had significantly higher BW increase than females (39.4 ~c 2.05%). Crabs stocked at sizes of 51-60 g showed significantly greater percent increase in BW (43.26~c 0.98%) compared with those at 61-70 g (40.98~c1.33%), 71-80 g (38.55~c 1.04%), 81-90 g (36.34 ~c 1.27%) and 91-100 g (38.52 ~c 1.67%). Among the three species, hatchery-reared S. serrata (42.14 ~c 1.34%) had significantly higher mean percent BW increase compared with S. olivacea (38.23 ~c 0.49%) and S. tranquebarica (36.16 ~c 0.78%). S. serrata had significantly shorter mean culture period (24.11 ~c 0.95 days) than S. tranquebarica (28.48 ~c 0.54 days) and S. olivacea (28.75 ~c 0.34 days).
    • Article

      Reproductive development of the threatened giant grouper Epinephelus lanceolatus 

      The giant grouper is presumed to follow the reproductive pattern of most Epinephelus species, characterized by protogynous hermaphroditism wherein male maturation is attained through sex reversal of a functional female. This hypothesis, however, has not been verified due to lack of biological data. The present study addresses this gap by investigating the reproductive development of giant groupers from juvenile stage through sexual maturity. Gonad histological analysis of hatchery-bred juvenile giant grouper from Queensland, Australia (0.8–5.2 kg, n = 43) have shown earliest occurrence of primary oocytes (i.e. ovarian differentiation) in 47.8 cm and 2.5 kg fish. Monitoring of sexual maturity by gonadal biopsy was performed in a stock of wild-caught giant groupers (2–52 kg) held in sea cages in the Philippines and Vietnam from 2015 to 2017. Onset of female sexual maturity was at 96.9 ± 1.6 cm and 23.5 ± 1.5 kg in the Philippines, and 103.0 ± 4.1 cm and 33.5 ± 2.5 kg in Vietnam. In both locations, development of primary males was observed wherein fish produced milt (or spermiated) without passing through a functional female phase. The ratio of primary males to females in both locations was about 1:2. Size at maturity of primary males is 86.5 ± 4.8 cm and 17.1 ± 2.1 kg in the Philippines, and 97.3 ± 1.3 cm and 34.3 ± 0.9 kg in Vietnam. To aid in the monitoring of female maturation, we developed a non-invasive method based on immunoassay of vitellogenin in skin mucus and this was shown to be effective in detecting female maturation 9 ± 2 months prior to first observation of oocytes through gonadal biopsy. Our findings suggest that giant grouper is a diandric protogynous hermaphrodite. This study provides novel information on the reproductive biology of giant grouper, an economically important and vulnerable species.
    • Book

      Soft-shell crab production using hatchery-reared mud crab 

      EJ Tobias-Quinitio, GXS Libunao, FD Parado-Estepa & AT Calpe - 2015 - Aquaculture Department, Southeast Asian Fisheries Development Center; Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (PCAARRD)
      Series: Aquaculture extension manual; No. 61
      "The production of soft-shell crabs is well established in other Asian countries but its sustainability is already being threatened due to the decreasing mud crab population in the wild where the seedstocks are sourced. In the Philippines, production of soft-shell crabs has only been practiced recently due to lack of seedstock and technology. Sourcing of crablets from the natural environment is not encouraged due to dwindling populations of all sizes of mud crabs. Instead, it is recommended that crablets for soft-shell crab production come from hatcheries. The project on soft-shell mud crab production at SEAFDEC/AQD started in 2012 and was later funded by the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development of the Department of Science and Technology. The project is adopting the individual crab culture sytem of Thailand and Myanmar in pilot-scale and uses hatchery-reared crablets grown to 60-100 g in earthen ponds and stocked in trays. The pilotscale soft-shell production set-up is showcased at the Dumangas Brackishwater Station of SEAFDEC/AQD using crab boxes available in the country. Various sectors are interested to learn how soft-shell crabs are produced. Hence, the previous manual on Soft-shell Mud Crab Farming by Emilia T. Quinitio and May Myat Noe Lwin published in 2009 was revised to include the recent refinements using hatchery-reared crabs and locally available materials. This manual includes sections on the biology of mud crab, how to set-up the facility, management of soft-shell crab production and the cost and return analysis. We hope that various sectors will benefit from this revised manual" -- Foreword