Status of mud crab industry in the Philippines
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Mud crab farming has long been established in the Philippines. Scylla serrata, S. tranquebarica and S. olivacea are the common species found in the Philippines. S. serrata is the preferred species for farming by crab growers. The total production of mud crab from aquaculture was estimated at 13,720 valued at US$77,025,000 and 14,437 tons valued at US$86,511,000 in 2009 and 2010, respectively. The sources of crab seeds for farming are from the wild and in recent years, from the hatchery although in small percentage. The overexploitation of mud crabs and habitat losses have resulted in both reduced landings and mean capture size. To stem the wild harvest, the provincial and municipal government along with the Bureau of Fisheries and Aquatic Resources have introduced ordinances that prohibit the gathering and selling of crablets (≤ 3 cm) outside the municipality of origin. This resulted to increased acceptability of hatchery-reared crabs by crab growers.Basic technologies in all phases of culture (hatchery, nursery and grow-out) have been developed. However, there are still several issues that need to be addressed. In the hatchery phase, one of the major causes of low survival are the Molt Death Syndrome in which zoea 5 has difficulty molting to megalopa and diseases due to bacterial and fungal infection in eggs and larvae. The use of antibiotics as treatment for Vibrio spp. has proven to improve larval survival. However, the use of antibiotics can lead to the development of resistant strains of bacteria and abnormalities that become apparent at the juvenile stage.In the nursery phase, economic losses have been attributed to cannibalism. Providing sufficient food and shelters, reducing stocking density, size grading and removal or trimming of claws are the common strategies used to mitigate the high level of cannibalism. Recent findings showed that incorporating tryptophan in the diet can reduce the aggressive behavior of crabs. In the grow-out phase, culture of juvenile crabs to market size with one or two more commodities in earthen brackishwater ponds is the most prevalent practice. Due to the cannibalistic nature of mud crab, polyculture (usually with milkfish and shrimp) pond is carried out. Stocking density of each commodity varies with the size and the number of seed stock available and the abundance of natural food growth in the pond. Culture period ranges from 4-5 months. Monoculture of crabs is usually done for short term culture as in fattening in various systems. Mud crab culture is also integrated with the existing mangroves. Formulated diets have been verified in commercial grow-out ponds and showed promising results. Mud crabs are commonly fed with low value fish, molluscs and other unprocessed natural foods. Mortality in mud crabs in grow-out phase is oftentimes due to the white spot syndrome virus.The domestication of S. serrata has been done at SEAFDEC/AQD. The duration from spawning of the base population to F1 broodstock size was 10-14 months and from F1 to F2 was 11-12 months. Selective breeding of S. serrata is currently being done. The results serve as guide to understand and eliminate the obstacles to broodstock management and seed production. Recently, The Department of Science and Technology has funded the National Mud Crab Science and Technology Program being implemented by SEAFDEC/AQD and University of the Philippines Visayas to refine the existing technologies in all phases of culture and to aggressively promote the establishment of several mud crab hatcheries and nurseries in the Philippines. The Bureau of Fisheries and Aquatic Resources is also implementing the Philippine National Aquasilviculture Program, which includes the rehabilitation of mangrove forests and culture of commercially important aquatic animals including mud crab in established mangrove areas. On-site training on all phases of culture of mud crab has also been done by SEAFDEC/AQD not only in the Philippines but also in other countries like Brunei, Myanmar, India and Timor Leste. With the establishment of several hatcheries and nurseries, there will be sufficient seed stock supply for farming, thereby decreasing the dependence on wild stock.
Quinitio, E. T. (2015). Status of mud crab industry in the Philippines. In E. T. Quinitio, F. D. Parado-Estepa, Y. C. Thampi Sam Raj, & A. Mandal (Eds.), Proceedings of the International Seminar-Workshop on Mud Crab Aquaculture and Fisheries Management, 10-12 April 2013, Tamil Nadu, India (pp. 27-35). Tamil Nadu, India: Rajiv Gandhi Centre for Aquaculture (MPEDA).
PublisherRajiv Gandhi Centre for Aquaculture (MPEDA)
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BookEJ 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
Conference paperK Ganesh, GK Dinakaran, T Sundaresan, K Satheesh Kumar, KV Gangadharan, S Viswanathan, S Pandiarajan & YC Thampi Sam Raj - In ET Quinitio, FDP Estepa, YC Thampi Sam Raj & A Mandal (Eds.), Proceedings of the International Seminar-Workshop on Mud Crab Aquaculture and Fisheries Management, 10-12 April 2013, Tamil Nadu, India, 2015 - Rajiv Gandhi Centre for Aquaculture (MPEDA)Soft-shell crab production is being practiced in many Asian countries but the major source of seedstock is from the wild, which could no longer sustain the increasing demand. Commercial scale soft-shell crab production can become sustainable only if there is a continuous supply of seedstock not dependent on wild stock. Rajiv Gandhi Centre for Aquaculture (RGCA) under the Marine Products Export Development Authority (MPEDA) has established a pilot-scale mud crab hatchery at Thoduvai, Nagapattinam District, Tamilnadu in 2004 with the technical assistance from SEAFDEC/AQD. At present, RGCA has the biggest mud crab hatchery in India and a demonstration farm at Karaikal, U.T. of Puducherry, where nursery rearing, grow-out and soft-shell crab production are conducted using hatchery- produced mangrove crabs or mud crabs, Scylla serrata. This paper presents the results of the soft-shell crab production using hatcheryproduced S. serrata juveniles maintained in perforated low density polyethylene (LDPE) boxes. The duration of the molt interval, time of molt (day or night) and the increase in body weight and carapace width of each size group (40-60, 61-80, 81-100, 101-120, 121-140, 141-160, 161-180 g) after molting were determined.Results showed that the percentage increase in body weight and carapace width increased as the crabs grew bigger. Likewise, the molt interval was longer in bigger-sized groups of crabs. Sixty to seventy percent of the population molted during night time and the next molt occurred within 25 days in 80-160 g size groups. Soft-shell crabs in boxes within the water surface and juvenile crabs (2.5 cm CW initial size) for culture until market size in the pond can be a viable technology technology for mud crab growers.
Monosex culture of the mud crab Scylla serrata at three stocking densities with Gracilaria as crab shelter AT Triño, OM Millamena & CP Keenan - In CP Keenan & A Blackshaw (Eds.), Mud Crab Aquaculture and Biology. Proceedings of an International Scientific Forum, 21-24 April 1997, Darwin, Australia, 1999 - Australian Centre for International Agricultural ResearchThe effects of three levels of stocking density (0.5, 1.5 or 3.0/m2) and monosex culture (male or female) on the growth, survival and production of Scylla serrata were investigated. Juvenile crabs were stocked in 150 m2 enclosures in earthen ponds with Gracilaria as shelter and fed a mixed diet of 75% fresh brown mussel flesh and 25% fish bycatch. There was no interaction between stocking density levels and monosex culture (P<0.05) so the data were pooled for each sex or stocking density treatment. Results showed that highest survival was obtained from a stocking density of 0.5/m2 (P<0.05). Crab growth at different stocking densities was not significantly different (P>0.05). Highest return on investment (ROI) and lowest production costs were attained from 0.5/m2. Partial budgeting analysis showed that no net benefit accrued from stocking beyond 1.5/m2. Male crabs attained significantly better (P<0.05) final weight and specific growth rate than female crabs. Length, width, survival and production between male and female crabs were not significantly different (P>0.05). Male and female monoculture gave high net revenue and ROI of more than 100 but male monoculture is more profitable. Overall the results suggest that the culture of male or female mud crabs at 0.5–1.5/m2 with Gracilaria is economically viable.