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Conference paper
Mud crab fattening project of KAMAMANA in Del Carmen, Siargao Island
- 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 CenterThe Kaanib ng mga Mangingisda at Magsasaka ng Numancia Aqua-Agrikultura (KAMAMANA), established in Del Carmen, Siargao Island in 2011 is a People's Organization active in promoting the advocacy in 1) protecting the environment and natural resources, 2) providing services for the family welfare, and 3) managing sustainable livelihood programs and community development. One of the major livelihood programs presently being implemented by KAMAMANA is the fattening of mud crab (mangrove crab), Scylla serrata, in plastic containers set up in a mangrove area. Tenurial rights to manage a 2-hectare mangrove area for 25 years was granted to KAMAMANA by the Department of Environmental and Natural Resources.Crabs obtained from the mangrove areas of Del Carmen and nearby municipalities are purchased and stocked in plastic containers. The crabs are fed trash fish and mollusks once every afternoon to satiation until they are fattened, usually for 1-2 weeks. The major problem encountered is mortality after molting. Four KAMAMANA members are involved in the crab fattening. When mortalities occur, the dead crabs are usually charged to members assigned in the operation. The fattened crabs are sold to local restaurants, hotels, resorts and walk-in buyers or brought to traders in Surigao City. The net income is divided into the following: members involved in the culture (50%), treasurer (10%), business manager (15%), organizational share (5%), savings (5%) and trust fund (15%). -
Conference paper
Biological evaluation of existing feed formulations for the grow-out culture of the mud crab, Scylla serrata
- 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 CenterThis study was conducted to identify a formulated pelleted feed for the grow-out culture of the mud crab. A commercial crab feed (CCF) was evaluated together with fish by-catch (FBC) and three test diets (formulated and pelleted) of similar dietary energy (1723 MJ/Kg diet) based on published works. The test diets contained 48% (D-1), 43% (D-2), and 38% (D-3) crude protein (CP), respectively. All the five dietary treatments were fed to crablets (5 to 6 g body weight) that were individually stocked in 60-L tanks. Each dietary treatment was fed to six crabs. Crustaceans grow by molting which is not simultaneous, hence, each crab was monitored daily. After the third molt (M3) survival rates in D-1, D-2 and D-3 ranged from 33%-66% compared with only 16% in FBC, and 0% in CCF where no crab survived to molt for the second time (M2). Nutrients in FBC may not be sufficient to sustain growth and survival, while water stable CCF may lack a feed attractant. Diets D-1, D-2, and D-3 were evaluated in another feeding experiment to identify the basal diet for the crab. All crabs molted until M3 and no significant differences were noted on growth performance between treatments. However, D-1 (48% CP) was identified as the basal diet due to better numerical values observed in terms of feed conversion ratios and specific growth rates. -
Conference paper
Trading of juvenile crabs and grow-out culture in Capiz
- 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 CenterThe article presents the trade of juvenile crabs in the Province of Capiz, Philippines. Moreover grow-out culture was also presented. Likewise, common problems encountered in the trade, and culture of the crabs was discussed. -
Conference paper
Overview of the mud crab industry in the Philippines
- 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 CenterMud 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. -
Conference paper
Philippine National Standard for Live Mud Crabs: establishing food safety and quality requirements
- 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 CenterThe Bureau of Agriculture and Fisheries Standards (BAFS) of the Department of Agriculture (DA), in collaboration with the relevant government and research agencies, academe and industry organization, is currently developing the Philippine National Standard (PNS) for live mangrove crabs (also known as mud crabs). This PNS defines the food safety and quality requirements for live mangrove crabs in order to ensure consumers’ health and make the product globally competitive. The process in the development of standards include review of the existing requirements of local and foreign markets and internationally recognized standards, creation of the Technical Working Group, initial drafting of the PNS, conduct of public consultations in major production areas, finalization of the draft for the PNS, notification to the World Trade Organization and approval of the DA Secretary.The PNS for live mangrove crabs specifies the scope of the standard, product description, essential composition and quality factors, hygiene, handling, labeling requirements, methods of sampling, examination and analysis, definition of defectives, and the requirements for product lot acceptance. -
Conference paper
Unified provincial fisheries law enforcement of ordinance of Camarines Norte focusing on mud crab
- 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 CenterDue to overfishing and widespread coastal habitat degradation, the Province of Camarines Norte passed a provincial fisheries law enforcement known as the Unified Provincial Fisheries Law Enforcement Ordinance of Camarines Norte (UPFLEON) (P.O. 50-10). Given emphasis in the paper is the banning in the collection and possession of less than 1.0 cm juvenile crabs. -
Conference paper
Recent developments and enhancing transfer of the nursery technology for the mud crab Scylla serrata
- 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 CenterThe development of hatchery techniques for seed production of mud crab is expected to address the present problem on the depletion of wild seedstock supply for stocking in grow-out ponds. The nursery serves as the link between the two phases of culture as this involves growing of juvenile crabs produced in the hatchery to sizes that are suitable for stocking in the ponds.Nursery rearing involves the use of net cages installed in ponds as holding system for ease in harvest and retrieval of crabs. In the first nursery phase, 0.3-0.5 cm carapace width (CW) juvenile crabs are reared to 1.5-2.0 cm CW for 3-4 weeks and stocks are harvested for selling or are grown further in a second nursery phase in which crabs reach 2.5-3.0 cm after another 3-4 weeks. This paper includes a review of techniques initially developed for the nursery and more recent refinements which involve the use of higher crab instar densities, provision of suitable shelters, trimming of claws and sorting. In addition, production results in farms of collaborators are presented to highlight the efficiency of dissemination and also discusses the challenges faced by the potential nursery industry. -
Conference paper
Updates on the larviculture of mud crab at SEAFDEC/AQD
- 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 CenterAlthough the mud crab (Scylla serrata) hatchery technology has been developed, issues such as high cost of production due to the need for additional facilities and labor for natural food culture, inconsistent survival rate at megalopa stage due to Molt Death Syndrome (MDS), and disease due to luminescent bacteria (Vibrio spp.), remain to be addressed. Refinements on the existing mud crab larviculture technology were done to address these problems.Poor nutrition, low water temperature and application of prophylaxis during the zoea l stage have been identified as possible causes of MDS. Six shrimp formulated diets (FD) were tested, and 3 of these proved to be suitable for mud crab larvicuture. Larval performance was compared using the 3 diets + natural food (NF, rotifers and Artemia) and NF alone as control. No significant difference was noted in the survival among the 4 treatments, although BP Nippai fed larvae had higher values. Lesser occurrence of MDS was observed in all the larvae fed FD+NF. Three mud crab larval diets with various attractants (squid, annelids, and squid + annelids) were also formulated and fed to the larvae. Results showed no significant difference among the 3 diets. The results of another experiment investigating the effects of the reduction of natural food showed that larvae fed 50% NF + 50% FD and 75%NF + 25% FD had higher survival compared to those fed 75% AD +25% NF and no NF at all. The results indicate that the larvae cannot survive with formulated diet alone. It has been observed that frequency of antibiotic application can be reduced to every 5 days if good quality mud crab larvae are used. Formalin stress test proved to be a reliable method to determine the quality of a batch of newly hatched zoeae. All prophylactic treatments are stopped when megalopae reach the benthic stage.To accelerate the dissemination of science-based mud crab hatchery technology to industry stakeholders, SEAFDEC/AQD entered into an agreement with private hatchery operators, State Universities and Colleges, and Local Government Units on giving assistance during initial hatchery operations. Technicians were given free training, followed by in-situ hatchery operations with assistance from SEAFDEC/AQD with the funding from PCAARRD-DOST. Crablets are now being produced by the collaborators. Increase in the production of hatchery-reared crablets will eventually reduce the dependence on wild-sourced mud crab seed stock for farming. -
Conference paper
Capacity building initiatives of Winrock International on mud crab culture in the Caraga Region
- 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 CenterThe paper presents the output of the capacity building initiatives of Winrock International on Mud crab culture in the Caraga Region, Philippines. The capacity building seminar included lectures on the mud crab biology, pond preparation, nursery and grow-out culture, fattening, and soft-shell crab farming. Identification of the various crab body parts, actual pond preparation, nursery and grow-out culture of crab were demonstrated after the series of lectures. -
Conference paper
Mud crab production trials at the College of Fisheries and Marine Sciences, Aklan State University, New Washington, Aklan
- 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 CenterTwo hatchery and nursery trials have been conducted at the College of Fisheries and Marine Sciences, Aklan State University (ASU) for the Multi-species Hatchery and Fishfarm Project from August to September 2014 and April to May 2015, in collaboration with the Aquaculture Department (AQD), Southeast Asian Fisheries Development Center (SEAFDEC) under the National Mud Crab Science and Technology Program of the PCAARRD-DOST.Two ASU staff underwent training on Mud Crab Hatchery, Nursery and Grow-out Operations at SEAFDEC/AQD from September to October 2013. This was followed by SEAFDEC/AQD’s provision of technical assistance during the actual hatchery and nursery operations using Scylla serrata at ASU. Survival rates of 3% and of 66-76% were recorded in the hatchery and nursery phases, respectively. The natural food consisting of rotifer and Artemia, and commercial formulated diet were fed to S. serrata larvae (zoea to megalopa). Juvenile crabs were fed formulated feeds and molluscs. Water temperature ranged from 27 to 30°C and salinity from 29 to 33 ppt in the hatchery. Initial results and insights are discussed and evaluated as guide for future hatchery and nursery protocols. -
Conference paper
Population structure of Scylla serrata from microsatellite and mtDNA markers
- 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 CenterDetermination of the population structure and connectivity of natural populations of Scylla serrata are useful tools for decision making related to conservation and management efforts of this species. They provide important considerations as recovery and sustainability of the industry relies on the availability of hardy recruits that can replenish harvested resources from the system. In the case of marine domesticated species, admixture is expected due to commodity trade and exchanges.Current population structure of five wild populations of S. serrata from Pangasinan, Bataan, Cagayan, Quezon, and Panay was determined using five microsatellite markers, cross-amplified from Scylla paramamosain in a total of 259 samples. Mitochondrial 16S rDNA sequences of 25 representative individuals from the same locations were used to provide a comparison with original evolutionary patterns. Quality check of microsatellite data revealed no null alleles in the data set, with all loci and populations exhibiting Hardy-Weinberg Equilibrium. Pairwise FST analysis reveals FST values between 0.001-0.08432 with 9 out of the 16 possible comparisons considered significant. Phylogenetic analysis was performed on the 16S rDNA sequences, supported by bootstrap values. Both sets of data suggest 2 distinct groupings: the east coast populations of Cagayan and Quezon, the west coast populations of Pangasinan and Bataan, with admixture observed in the group from Panay. Additional data from 5 microsatellite markers specifically developed for S. serrata and the D-loop region will be added to the analysis.The results from both mitochondrial and microsatellite markers, revealing an East-West separation of S. serrata populations, suggest that current and evolutionary population patterns are matching. Aquaculture practices appear to have not yet significantly affected the population structure of this domesticated species, as initially speculated. -
Conference paper
Genetic diversity and stock delineation of Philippine populations of the orange mud crab, Scylla olivacea
- 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 CenterThe orange mud crab, Scylla olivacea, is regarded as an important fishery resource due to high demand and high market value. However, mud crab populations are threatened by over exploitation and habitat degradation, and would benefit from resource management interventions. The study examined patterns of genetic diversity and connectivity of orange mud crab populations across the Philippines, with the aim of identifying putative management units. A total of 387 Scylla olivacea were collected from ten localities across the Philippine archipelago. Phylogenetic analysis of mitochondrial control region (mtDNA-CR) DNA sequences revealed cryptic diversity among Scylla olivacea specimens with four mitochondrial lineages recovered. Analysis of molecular variance revealed that Philippine populations do not constitute a single genetic stock (0ST=0.00262; P=0.00015). Thirteen microsatellite loci were also utilized as additional markers to infer population structure and estimate genetic variation. Overall, S. olivacea populations exhibit high haplotype diversity (mean h=0.9803) and nucleotide diversity (mean ~p3.46%), which may be indicative of a large, stable population within Philippine archipelagic waters. This study provides information on genetic diversity and population structure of S. olivacea, which will be useful towards developing management and conservation strategies for sustainable development of natural S. olivacea populations in the Philippines. -
Conference paper
Mud crab Scylla serrata hatchery operation
- 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 CenterThe initial exposure of the Santos family in aquaculture was the culture of milkfish (Chanos chanos) and mud crab (Scylla serrata) in brackishwater pond in Quezon. The milkfish fry were obtained from our own milkfish hatchery, in which several broodstock are maintained as source of eggs. The juvenile crabs for stocking were wild-caught obtained from Quezon, Camarines or Bicol Region traders. In the late 2012, SEAFDEC/AQD collaborated with the Mari-al Hatchery for the seed production of mud crab under the National Mud Crab S and T Program of the Department of Science and Technology. This collaboration was timely since the source of juvenile crabs was no longer reliable. Furthermore, excess crabs that would be produced from the hatchery can also be sold to other farmers. Training at SEAFDEC/AQD and technical assistance on site were provided by SEAFDEC/AQD prior to the operation of the mud crab hatchery. Part of the existing milkfish hatchery facilities were utilized for the crab larval rearing. The protocol of SEAFDEC/AQD was followed with some modifications based on the existing facilities and source of water supply. After the successful runs, a separate hatchery facility dedicated for mud crab larval rearing was constructed in 2013. Four runs were conducted with 1-2% survival rate from zoea 1 to crab instar. Problems encountered during the runs include: insufficient rotifers since the culture had to be shared with milkfish larvae, poor water quality due to typhoon and presence of a wharf nearby, low water temperature, human error, resignation of trained staff, lack of good quality broodstock source nearby, and MDS. The problems were addressed one by one. Although the technology has been developed, this has to be modified accordingly. -
Conference paper
High throughput RNA sequencing reveals temperature tolerance mechanisms in Scylla serrata
- 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 CenterThe effects of increasing temperature from global climate change threaten the sustainability and production of mud crabs from farms and wild populations in mangroves. Adaptation of mud crab populations to temperature stress is difficult to evaluate until now, with the emergence of RNA-Seq, a method which evaluates total mRNA expression under different conditions. In this study, 10 individuals each of S. serrata from Buguey, Cagayan were exposed to 26~’C and 32~’C for two weeks and the mRNA profiles were compared based on 186 million high quality pair-end reads which were aligned to a S. serrata reference transcriptome assembled de novo from 24,350 contigs with an average N50 of 1564 bp. Temperature related differences in gene expression were not significantly detected between the control and treatment groups and this was mostly due to the highly expressed genes such as the low and high molecular weight heat shock proteins. However, variations were greater among genes involved in the process of cell cycle regulation, the dissimilation processes such as oxidative phosphorylation, reproduction and transport across membranes. Greater differences were observed between immature or mature males and females. -
Conference paper
Identification of mud crab species in coastal areas of Pangasinan
- 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 CenterThe study was conducted to identify the mud crab species (Scylla spp.) that thrive in 12 coastal municipalities and 2 cities in Pangasinan. Ten mud crab samples were taken from each of the sampling site and classified based on Keenan et al. (1998). Likewise, the abundance and differences in size and weight of the mud crab samples were determined. The study showed that there are only three mud crab species, Scylla serrata, S. tranquebarica and S. olivacea, found in the coastal areas of Pangasinan. S. serrata was the most abundant species (54.28%), followed by S. tranquebarica (24.28%) and S. olivacea (22.14%). Crabs weighing more than 300 g (~.12 cm carapace width or CW) were obtained from the municipalities of Anda, Bolinao, Dasol, Burgos, Bani, Agno, Alaminos and Infanta. These municipalities are geographically situated in coastal areas where S. serrata are found. Crabs weighing below 300 g (~.12 cm CW) were collected from the municipalities of Sual, Labrador, San Fabian, Lingayen, Dagupan and Binmaley. These towns have mangrove areas and low saline waters where S. tranquebarica and S. olivacea thrive. -
Conference paper
Polyculture of mud crab in Region 3
- 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 CenterThe polyculture of mud crab with one to three other species (milkfish (Chanos chanos), tilapia (Oreochromis spp.) and shrimp or sugpo (Penaeus monodon)) is a common practice in Region 3. Pond preparation is given importance prior to stocking of various species. Removal of sludge in the pond and application of probiotics are included in the standard pond preparation. The size and stocking densities of each species vary depending on the season. The volume of water to be replaced is based on the transparency of the water.The various species are fed natural food grown in the pond in addition to mollusks and low value fish given specifically for mud crab and shrimp. When pond water becomes transparent (indicating the decrease in phytoplankton density), the water is agitated using a small boat. If water continues to be transparent, fertilizers are applied to enhance growth of natural food. The pond water and animals are closely monitored to prevent diseases. Some of the early signs of occurrence of disease include the presence of bubbles on the water surface, and presence of weak shrimp on the feeding trays and along the dikes. The presence of weak shrimp and crab on the pond bottom and continuous swimming of these animals from night to dawn indicate poor pond water quality which can be remedied by circulating and flushing of the pond water every other day. -
Conference paper
Diseases affecting wild and farmed mud crab in the Philippines
- 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 CenterMortalities due to cannibalism and diseases have been reported as major problems in the grow-out phase of mud crab production. This study aimed to identify and describe diseases affecting farmed and wild mud crab (mangrove crab) including predisposing, risk and protective factors, and possible prevention and control measures. A total of 767 wild and farmed mud crab samples were collected. External examination showed abnormalities such as short abdominal flap, discoloration of the abdominal region, darker carapace, lesions on carapace, claws and legs, and presence of epibionts like algae and the barnacles Balanus sp. on the carapace. Internally, necrotic, black and brown gills, and discolored gonads were observed. Stalked barnacles, Octolasmis spp., were observed in the gills. White spot syndrome virus (WSSV) was detected in 14 samples sourced from farms and Infectious hypodermal and haematopoietic necrosis virus (IHHNV) in 2 wild samples. WSSV was implicated in mortality cases. Low temperature and presence of WSSV positive shrimp were identified as risk factors for WSSV infection or outbreak. Pathogenicity tests for some isolated bacteria suggested that these may cause mortality in mud crab under stressful conditions. To prevent mortality due to WSSV infection, it is recommended to avoid polyculture of mud crab with shrimp and/or other crustaceans. -
Conference paper
Growth, survival, proximate and fatty acid composition of sandworm Perinereis quatrefagesi (Grube, 1878) fed variable feed types
- 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 CenterSandworm Perinereis quatrefagesi has been used as feed for crustacean broodstock due to its reproductive-enhancing properties particularly protein and highly unsaturated fatty acids (HUFAs). Juvenile sandworms collected along the coast of Guimbal, Iloilo were reared in tanks and fed three nutritionally variable feed types: fish fecal waste, fish meal and rice bran. After 56 days, feeds affected (p<0.05) sandworm growth and crude fat contents but not (p<0.05) survival and crude protein levels. Survival rates were 86~c3 to 89~c5% while crude protein levels were 57.0 ~c 2.5 to 68.0 ~c 5.3 g 100 g-1 dry weight. High crude protein fish meal promoted better (p<0.05) growth (2.2~c0.4% day-1) than fish feces (1.2~c0.3% day-1) and rice bran (1.1~c0.3 % day-1). However, crude fat content of sandworm was higher (p<0.05) in rice bran (18.9~c1.6 g 100 g-1) than in fecal waste (13.6~c2.9 g 100 g-1) and fish meal (10.5~c3.1 g 100 g-1) treatments. Levels of highly unsaturated fatty acids (HUFAs) such as 20:4 n-6, 22:6 n-3 and 20:5 n-3 did not differ significantly (p>0.05) at 0.41~c0.21 to 0.89~c0.51 g 100 g-1, 0.21~c0.24 to 0.43~c0.22 g 100 g-1 and 0.57~c0.46 to 0.88~c0.31 g 100 g-1, respectively.The study demonstrated that P. quatrefagesi: (1) can survive well in nutritionally variable feed types although it grows better in high protein diet; (2) crude protein levels were high regardless of feed types; and (3) crude fat content was high in high fat diet but n-3 and n-6 HUFAs were not significantly different regardless of feed types. -
Conference paper
Morphological deformities in mud crab Scylla serrata juveniles exposed to antibiotics during the larval stage
- 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 CenterThe effects of antibiotics on the survival, growth and external deformities of mud crab Scylla serrata larvae and juveniles were determined. Zoeae were exposed to 0, 3, 6, 9, 12 mgL-1 oxytetracycline (OTC) and 0, 0.5, 1, 1.5, 2 mgL-1 furazolidone (furan) until the late megalopa in the first and second experiments. The treatments that gave the best results in the first and second experiments were conducted simultaneously in the third experiment. The surviving crab instar from each replicate were grown in nursery tanks for one month.Significantly higher survival and faster growth rate of Z5 were attained when 3 and 6 mgL-1 OTC or 0.5 and 1 mgL-1 furan were used. Morphological deformities observed in zoea 5 were bent dorsal, rostral and furcal spines. Percentage occurrence of morphological deformities was similar in all treatments. Significantly (P<0.05) higher survival and faster growth were attained among Z5 in the treatments using 3 mgL-1 OTC and 0.5 mL-1 furan in the third experiment. Morphological deformities observed in juveniles were fused frontal and lateral spines, asymmetrical and depressed tip of abdominal flap and gap between sternites. High percentage of deformities was observed in juveniles that were previously exposed to 6 mgL-1 OTC or 1.0 mgL-1 furan. There was no significant difference (P>0.05) observed in the survival of juveniles in both treatments of OTC and furan. However, growth was significantly (P<0.05) faster in lower concentrations of the two antibiotics.The study shows the apparent negative effects of antibiotics and highlights the need to eliminate or find alternatives, thereby preventing possible harm to the organisms and the environment. -
Conference paper
Nursery culture of mud crab Scylla serrata fed diets supplemented with trytophan at two stocking densities
- 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 CenterCannibalism has been recognized as one of the major problems in crab culture. The use of dietary tryptophan (TRP) that has been reported to reduce cannibalism in crabs under laboratory conditions was verified in pond nursery culture at two stocking densities. The first phase used hatchery-produced early crab instar. After 3-4 weeks, survivors were sorted and the small size crabs were further reared in the second phase. Crabs were stocked in 12-m2 net cages installed in brackishwater pond and fed three times daily at 0830, 1300 and 1630 h. The feeding scheme used was a combination of mussel meat (M) and formulated diet (FD) at 30:70 ratio. The original FD contained 45% crude protein (used in Experiment 1, 2 and 3) that was lowered to 40% crude protein in the new basal diet used in the succeeding experiment. The two TRP-supplemented diets had 0.5% and 0.7% TRP levels. Results showed that the TRP-supplemented feeds did not give consistent results in terms of growth and feed conversion ratio, indicating that the original basal diet (0.4% TRP and 45% crude protein) or the new basal diet (0.4% TRP and 40% crude protein) were sufficient to be used together with mussel meat as feed for crab juveniles. Higher survival rates were obtained at 50 m-2 (phase 1) and 10 m-2 (phase 2) than at 30 m-2 and 5 m-2 stocking density, respectively. All trial runs produced positive returns on investment.
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