Seed production of mud crab Scylla serrata juveniles
View/
Date
2001Author
Page views
3,197ASFA keyword
AGROVOC keyword
Taxonomic term
Metadata
Show full item recordShare
Abstract
A protocol for the large-scale rearing of the mud crab Scylla serrata juveniles was developed based on the results of small-scale experiments on feeding and water management. This paper also reports the success in producing the second generation (F2) crabs.
Pond-reared adult S. serrata held in 10 m3 concrete tanks with sand substrates were given fish, mussel, annelids and formulated diet. The zoeae produced were stocked in 1.5 or 10 m3 tanks at 30 to 50 ind-l-1 and fed 10 to 15 Brachionus rotundiformis ml-1, 1 to 5 Artemia sauna nauplii ml-1 and 1.5 to 2.0 g shrimp larval commercial diet-m-3 day. Water was replaced daily at 30 to 50% of the total volume starting day 3. Megalops were nursed until crab stage either in tanks or in net cages installed in ponds. Crabs were fed mussel or small shrimps (Acetes sp).
Hatching occurred 6 to 12 days after spawning at 26.5 to 30.5°C. A female produced 0.42 to 5.23 x 106 zoeae at a time. Mean survival rate from zoea 1 to 3- to 5-day old megalopa was 2.6 ± 0.8% and 32.8 ± 4.8% from megalopa to crab stage. The development from zoea 1 to megalopa required 16 to 18 days. Cannibalism and luminescent bacteria were identified as the major causes of mortality. Highest mortality was observed during the metamorphosis from zoea 5 to megalopa and megalopa to crab 1. First crab stage was obtained 23 to 25 days after hatching. Sorting the crabs during the nursery period minimized cannibalism.
Completion of the cycle in captivity was attained in 1997 and 1999 when spawns from pond-reared crabs grew to become the second-generation broodstock. The results point to a minimum age of 7.5 to 9 months at which S. serrata hatched their eggs after rearing from zoea 1.
Suggested Citation
Quinitio, E. T., Parado-Estepa, F. D., Millamena, O. M., Rodriguez, E., & Borlongan, E. (2001). Seed production of mud crab Scylla serrata juveniles. Asian Fisheries Science , 14(2), 161-174. http://hdl.handle.net/10862/1910
Type
ArticleISSN
0116-6514Collections
- Journal Articles [1266]
Related items
Showing items related by title, author, creator and subject.
-
Overview of the mud crab industry in the Philippines
Quinitio, Emilia T.
(Aquaculture Department, Southeast Asian Fisheries Development Center, 2017)
Mud crab farming has long been established in the Philippines and the country is the second top producer in the world. Except for Scylla paramamosain, the three other species, S. serrata, S. tranquebarica and S. olivacea are commonly found in the country, but S. serrata is the preferred species for farming. Crab seeds for farming are mainly from the wild and in recent years, a small percentage from the hatchery. Due to the apparent decline of the wild crab stocks, provincial and municipal ordinances have been issued by a number of Local Government Units (LGUs) along with the Bureau of Fisheries and Aquatic Resources (BFAR) to conserve and manage the remaining resources. From the hatchery, megalopa or crab instars are grown in net cages installed in the nursery pond. Mud crab farming engages mostly in long-term grow-out culture of juvenile crabs to market size for 3-5 months, short-term fattening of lean crabs for 15-45 days, and recently, soft-shell crab production. Polyculture of juvenile crabs to market size with one to three other commodities in earthen brackishwater ponds is usually practiced. Mud crabs for soft-shell crab production are mainly from the wild, while SEAFDEC/AQD demonstrates the use of hatchery-produced juvenile mud crabs as seedstock. Refinement is continuously being done to improve the economic viability of producing crabs, although basic technologies have been developed for all phases of culture (hatchery, nursery, grow-out, fattening and soft shell crab production). The major issues facing the industry are the lack of seedstock, difficulty of zoea 5 to molt to megalopa stage, cannibalism particularly at the nursery phase, species identification at the juvenile stage, use of fish as aquafeed, diseases, effects of climate change and quality of crabs at postharvest. In 2012, the Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (PCAARRD) of the Department of Science and Technology (DOST) started funding projects under the National Mud Crab Science and Technology Program (NMCSTP) to address these issues. The major aim of the Program was to improve the production, profitability and sustainability of crab farming. SEAFDEC/AQD leads in capacity building with focus on the sustainability of the mud crab industry. Various collaborations and research studies on mud crab culture enabled SEAFDEC/AQD to package mud crab technologies, conduct local and international training courses and on-site technology demonstrations, and publish extension manuals and scientific publications since the mid1990s. Research and Development activities have been translated into improved production. With the recent developments and refinements of technologies, it is expected that the Philippines will increase its production by 25-50% in the next 5 years. -
Updates on the seed production of mud crab
Quinitio, Emilia T.; ; ; (Aquaculture Department, Southeast Asian Fisheries Development Center, 2015)
Widespread interest in mud crab species is increasing because these are highly prized both in domestic and export markets. Among the three mud crab species commonly found in the Philippines, Scylla serrata, S. olivacea, and S. tranquebarica, S. serrata is preferred by farmers because it is larger and less aggressive than the other species. Likewise, S. serrata is the most widely distributed species in the Indo-west Pacific region. Hatchery-produced seedstock are presently used by some crab farmers in their grow-out operations. In the hatchery phase, feeding mud crab larvae with shrimp formulated diets and natural food was found to reduce the occurrence of molt death syndrome, one of the major problems in seed production. Larvae given 25% formulated diet (FD) + 75% natural food (NF; rotifers and Artemia) and 50% FD + 50% NF showed better performance than those larvae fed 100% FD, 100% NF and 75% FD + 25% NF indicating that usage of natural food, especially the expensive Artemia, can be reduced. Since the early crab instar (C) produced in the hatchery need to be grown further before stocking in grow-out ponds, two phases of nursery culture have been developed. C1-2 are grown to 1.5-2.0 cm carapace width (CW) size in the first phase and further grown to 3.0-4.0 cm CW in the second phase. Nursery rearing is done in net cages installed in ponds for easy retrieval. A combination of mussel or trash fish and formulated diet is used as feed. Domestication of the mud crab S. serrata as a prerequisite to selective breeding has been done at SEAFDEC/AQD. Likewise, defining criteria for the determination of quality of newly hatched zoeae for stocking in the hatchery was initiated. Newly hatched zoeae were subjected to starvation and stress test using formalin. Starvation failed to elicit responses that were significantly different between the good and poor quality larvae hence it is not suitable for larval quality evaluation. Based on three-year data, the formalin stress test gave mean cumulative mortalities of 2.38±0.32, 8.24±0.88, 20±1.58 in good quality larvae, and 43.74±2.39 while 22.93±4.19, 63.68±7.17, 84.29±3.88 and 97.65±1.06 for poor quality larvae at 0 (control), 20, 30 and 40 ppm formalin, respectively. As formalin level increased, cumulative larval mortality also increased regardless of the quality of the larvae. Formalin stress test proved to be a reliable method to determine whether a batch of newly hatched zoeae was of good or poor quality. -
Development of protocol for the production of hatchery-reared mud crab Scylla serrata juveniles for soft-shell crab farming
Quinitio, Emilia T.; ; (Aquaculture Department, Southeast Asian Fisheries Development Center, 2017)
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).
