Recent Submissions

  • Conference paper

    Overview of the mud crab industry in the Philippines 

    ET Quinitio - 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
    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.
  • Conference paper

    Unified provincial fisheries law enforcement of ordinance of Camarines Norte focusing on mud crab 

    EA Estanislao - 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
    Due 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

    Biological evaluation of existing feed formulations for the grow-out culture of the mud crab, Scylla serrata 

    MR Catacutan - 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
    This 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 

    GJ Panaguiton - 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
    The 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

    Enhancing mud crab population through mangrove restoration 

    MJH Lebata-Ramos, EF Doyola-Solis, RC Sibonga, JB Biñas, M Walton & L Le Vay - 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
    Mangroves are known as important nurseries for different species of fish and shellfish. In the Philippines, mud crabs Scylla spp. are among the most valuable crustaceans harvested from the mangroves and are considered a delicacy. However, varying levels of overfishing have been reported in different parts of the country. The decrease in production may be due to increasing demand for the resource and the loss of mangrove habitat. This problem may be addressed through regulation of fishing effort, rehabilitation of habitats, mangrove-friendly aquaculture and enhancement of wild crab stocks. This study shows the effect of mangrove rehabilitation on mud crab population.

    From July 2010 to December 2011, a total of 2.166 tons of mud crabs (n=17,558) have been collected from a 66.5 ha abandoned pond that has been recolonized by mangroves. The catch was dominated by S. olivacea (79.96%), then S. tranquebarica (19.92%) and S. serrata (0.12%). Male to female ratio was at 1.09:1. Individual daily yield ranged from 0.06 to 8.4 kg while catch per unit effort in terms of quantity and biomass ranged 0.02-1.46 crab gear-1 day-1 and 1.1-213.54 g gear-1 day-1, respectively. The results showed that mud crab population in this study site was much higher than the population in the reforested (Walton et al., 2006, 2007) and natural mangroves (Lebata et al., 2007) with almost the same area. For 18 months of sampling (April 2002-September 2003), only 3,924 crabs were sampled in the natural mangroves while 10,504 in the reforested mangroves. Mud crab production in the present study site resulted in a yield of 21 kg ha-1 yr-1, 5 and 3 times higher than the yield reported in the natural and reforested mangrove areas, respectively. These results imply that habitat restoration can be very effective in restoring natural populations of mud crab.
  • Conference paper

    Handling, storage and transport conditions of mud crabs in trading centers 

    JP Peralta & JPD Chan - 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
    This study aims to improve the handling, storage and transport conditions of mud crabs. The usual practice of the crab growers in the Philippines is to bring the market size crabs to middlemen, brokers or operators of small trading centers immediately after harvest; then the crabs are brought to municipal traders or operators of bigger buying station. The crabs are sent to the exporters in Manila or Cebu. The crabs are exported mostly to Singapore, Taiwan, Hongkong and mainland China. The crabs are classified based on the species, body weight, sex, gonad maturity and intactness of limbs. Crabs are rejected for export when they are soft-shelled, very lean, or have incomplete limbs and abnormalities. Crabs with emaciated muscle (‘hagas’), ammoniacal odor (strong urine-like smell) and in an undesirable state are also rejected.

    This paper presents the initial results of the project on the Improvement in the handling, storage and transport of mud crabs under Sub-program C entitled Improvement of Feeds and Stock Management Practices in Mud Crab Grow-out Culture under the National Mud Crab Science and Technology Program. It also presents issues and concerns on the present practices, and presents possible recommendations.
  • Conference paper

    Development of aquasilviculture at BFAR-NBFTC, Pagbilao, Quezon 

    RE Dieta & FC Dieta - 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
    Aquasilviculture technology verification project was conducted at the National Brackishwater Fisheries Technology Center (NBFTC) of the Bureau of Fisheries and Aquatic Resources (BFAR) in 1996-2000. Results indicated that given the proper technology, management and favourable market, and polyculture of high-value species (grouper (Epinephelus) and mud crab (Scylla)) will provide better return on investment. Dissemination of the technology through training started in 2001. In 2002, a 4-hectare undeveloped fishpond of NBFTC was converted into an aquasilviculture project to showcase the technical and economic feasibility of the technology with emphasis on the polyculture of mud crab, grouper and saline tilapia (Oreochromis) that would serve as a model livelihood project for coastal fisherfolk. In 2011, the BFAR launched the Philippine National Aquasilviculture Program to help restore mangroves that serve as breeding and nursery grounds of fish, and to provide livelihood projects through aquasilviculture to coastal fisherfolk. With increasing cost of development and management for aquasilviculture, integration of mangrove crab fattening and/or soft-shelled crab production have shown to improve profit under the present economic condition.
  • Conference paper

    Growth, survival, proximate and fatty acid composition of sandworm Perinereis quatrefagesi (Grube, 1878) fed variable feed types 

    JB Biñas, VR Alava & WL Campos - 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
    Sandworm 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

    Evaluation of the bioremediation capacity of the polychaete, Marphysa mossambica (Peters, 1854) in pond sediments 

    MAE Mandario, VR Alava & NC Anasco - 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
    Marphysa mossambica is commonly found in brackishwater ponds and is an important natural food for cultured stocks particularly mud crabs. To understand the burrowing activity of polychaete, survival and capacity to bioremediate pond sediments, tank experiments were conducted. In a completely randomized design with three replicates per treatment, small (1-month old, 28 mg) and large (3-month old, 139 mg) hatchery-bred M. mossambica were reared in two sediment types for 30 days without feeding. Aeration was supplied and water change was done every other day. Polychaete-free sediments served as control. Sediments obtained from SEAFDEC/AQD Dumangas Brackishwater Station were sun-dried, ground and passed through 1-mm sieve.

    Initial sediment A had 1.86% organic matter, 1,171 ppm available sulfur (SO42-), 194.23 ppm iron (Fe) and 7.86 pH while initial sediment B contained higher organic matter (4.1%), available sulfur (2,456.67 ppm), similar iron level (199.34 ppm) and was more acidic (4.91 pH). In sediment A, small and large polychaetes did not differ (p>0.05) with the control in reducing organic matter but both significantly reduced (p<0.05) available sulfur (77-73%) and iron (69-71%). However, only the large polychaetes increased the pH (p< 0.05, 2.67%). In sediment B, only the large polychaetes reduced (p<0.05) organic matter (27%) but both small and large polychaetes significantly reduced (p<0.05) available sulfur (64-70%) and iron (70-74%). The pH increase was similar to control (17-24%). Large polychaetes had higher survival (93%, p<0.05) than small polychaetes (60%) in sediment B but not different (p>0.05) in sediment A (97%, 87%). The study demonstrated the bioremediation capacity of M. mossambica particularly in reducing available sulfur and iron in sediments.
  • Conference paper

    Adoption of modified commercial scale mud crab hatchery and nursery systems in Alaminos City, Pangasinan 

    RB Cerezo & JF Rebugio - 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
    Pangasinan’s vast fishpond and mangrove areas have not been fully tapped for mud crab (Scylla serrata) production. The main reason identified for this is the limited supply of crab seedstock. At present, there is no reliable source of seedstock in Pangasinan. The total requirement of Pangasinan for crab seedstock is estimated at 8.89 million based on the total area (ha) devoted to mud crab polyculture in the province. Mud crab growers in Pangasinan procure wild juvenile crabs from Cagayan, Bicol and Visayas but the volume is limited. Thus, an adoption of a modified commercial scale mud crab hatchery and nursery systems in Alaminos City would be helpful. A model mud crab hatchery will be constructed to enable the local government unit (LGU) of Alaminos City to produce seedstock in commercial quantity to boost the production in Pangasinan and nearby provinces. The hatchery aims to produce 480,000 juvenile crabs per year to supply the nursery and grow-out ponds. Likewise, the hatchery technology will promote the mud crab hatchery and nursery technologies in the city of Pangasinan and coastal towns (Infanta, Dasol, Burgos, Agno, Bolinao, Anda, Bani, Sual, Labrador, Lingayen, Binmaley, Dagupan City and San Fabian), and nearby provinces of La Union, Ilocos Sur, Ilocos Norte and Zambales.
  • Conference paper

    Private sectors perspectives: Problems and constraints of the mud crab grow-out industry 

    HR Hocson - 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
    Mud crab aquaculture industry in the province of Capiz received much attention after production constraints due to diseases were encountered by the prawn industry. Fishpond operators sought for an alternative high value species and realized the potential of the king crab, Scylla serrata. This species is not native to Capiz and has to be sourced from other parts of the country, particularly from the Bicol region and Samar. The techniques for grow-out culture were gradually refined as farmers learned from the experiences of others. Presently, mud crab aquaculture is being done by private sectors based more on art. However, mud crab culture requires a lot of science to make the production consistent and sustainable. The practices of farmers and the problems they have encountered are presented together with the overall industry concerns.
  • Conference paper

    Diseases affecting wild and farmed mud crab in the Philippines 

    EA Tendencia & MVC Cabilitasan - 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
    Mortalities 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

    Initiatives on mud crab culture at the Palawan Aquaculture Corporation 

    E Tech, C Emboltorio, D Galila, C Ogsimer & K Lim - 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
    Mud crab (Scylla spp) has long been a prime commodity in both local and global market and is regarded as one of the important high-value crustacean species produced in the Philippines. Decades ago, its culture basically relied on the availability of wild seedstock collected and grown to marketable size, or on wild lean adult crabs that were fattened for a short period.

    Developments and refinements in the hatchery and nursery techniques paved the way to bringing up culture activities to commercial levels. The Palawan Aquaculture Corporation embarked on mud crab culture in the mid 2014 where initial trials started. Collaboration with SEAFDEC/AQD was later forged bringing forth improvements in the hatchery, nursery and grow-out culture. Hatchery-reared juvenile crabs are now being sold.
  • Conference paper

    Management strategies for grow-out culture of mud crab 

    JG Genodepa - 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
    There is an increasing interest in mud crab farming because of the growing demand for mud crab in domestic and international markets. Different methods for rearing crabs in ponds, pens and cages have evolved through several years of research and experiences of farmers. Mud crabs are cultured in brackishwater earthen ponds and pens in mangroves. Fattening of lean crabs is also integrated with the grow-out culture system. Cannibalism is one of the major factors affecting the survival of crabs in growout ponds and pens. Hence, various strategies are recommended to reduce cannibalism such as stocking density of less than 2,000 crabs ha-1, provision of suitable shelters, sufficient quantity of natural food and formulated feeds that are evenly distributed in the pond or pen. Feeding rate used in the pen is adjusted to avoid excess feeds that can attract rats and other land animals that can damage the enclosures. Selective harvesting is normally practiced since mud crabs do not grow or get fattened at the same time even if they belong to the same batch.
  • Conference paper

    Morphological deformities in mud crab Scylla serrata juveniles exposed to antibiotics during the larval stage 

    GS Pates Jr., ET Quinitio, GF Quinitio & 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
    The 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 

    VR Alava, MA Lucero, JD Sumile & 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
    Cannibalism 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.
  • Conference paper

    Induction of molting in hatchery-reared mud crab Scylla serrata juveniles through temperature manipulation or autotomy 

    JJDC Huervana - 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
    The effects of water temperature and autotomy of chelipeds on growth, survival and molting of mud crab, Scylla serrata, juveniles were investigated under laboratory conditions in separate experiments. Hatchery-produced crabs at the intermolt stage with 2.0-2.3 cm carapace width and 1.7-2.2 g body weight were either exposed to temperature levels of 29, 32 and 35°C and ambient temperature of 24-31°C or subjected to autotomy (voluntary removal of one or two chelipeds). The crabs were allowed to molt twice prior to termination.

    All crabs held at 35°C had 100% mortality due to incomplete molting during the first molt. The mean survival of crabs upon termination was 58, 64 and 50% for ambient temperature, 29 and 32°C, respectively. Specific growth rate (SGR) of crabs in the ambient (2.83 ± 0.12%) and 29°C (3.02 ± 0.15%) were comparable but significantly lower than (P<0.01) those at 32°C (3.85 ± 0.28%). The molt interval of crabs was significantly shorter in treatments with constant water temperature (29°C: 32 ± 0.80 days, 32°C: 28 ± 1.11 days) compared to ambient temperature (39 ± 0.93 days).

    The survival of crabs with intact chelipeds (51.17 ± 3.56%) was comparable to those with one (50.55 ± 2.36%) or two (43.41 ± 1.59%) autotomized chelipeds. Juveniles with intact (5.80 ± 0.47%) or one autotomized cheliped (5.45 ± 0.30%) had a significantly higher SGR than crabs with both chelipeds autotomized (4.20 ± 0.52%) in the first molt. On the second molt, however, high SGR was observed in crabs with two chelipeds autotomized. The molt interval was significantly shorter in the autotomized crabs (one cheliped: 28 ± 1.66 days; two chelipeds: 23 ± 0.63 days) compared to those with intact chelipeds (36 ± 1.52 days). The results suggest that optimum water temperature for rearing S. serrata juveniles ranges from 29 to 32°C. Likewise, autotomy of one cheliped can promote molting without adversely affecting the growth and survival of the juveniles.
  • Conference paper

    Effect of feed binder on water stability and digestibility of formulated feed for the mud crab Scylla serrata 

    MR Catacutan - 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
    The binding capacity of six natural and eight synthetic feed binders were tested in a basal diet formulated for the mud crab. Incorporation levels of natural binders ranged from 1 to 25% while those of synthetic binders ranged from 0.1 to 5% and these were tested for pellet stability in seawater by a) 10-min immersion, and b) at different time intervals. Pellets with synthetic binders were more water-stable than pellets with natural binders. Three synthetic binders and natural binders (glutinous rice starch and carrageenan + CMC) showed best results. The Apparent Digestibility Coefficients (ADC) of crude protein (ADCCP) and crude fat (ADCCFt) of the basal diet were determined when selected feed binders were included in the formulation. These were determined by using an inert indicator, chromic oxide. Results showed that the ADCCP and ADCCFt of the basal diet were not similar when different binders were used, and these differences ranged from 3 to 7%. Carrageenan combined with a synthetic binder improved ADCCP and CDCCFt values.
  • Conference paper

    Mangroves as mud crab habitats 

    JH Primavera - 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
    The paper reports the use of mangroves by Scylla species both as wild and culture habitats. Based on published literature, natural mangrove crab populations are described in terms of population density, dispersal and movement within and outside mangroves, crab burrows and associated mangrove species. Strategies for Scylla conservation depend on the kind of mangrove habitat - (mangrove) restoration for open fringing mangroves where crab recruitment and abundance are determined by habitat availability vs stock enhancement in closed basin mangroves with restricted recruitment and limited movement of crabs.

    Mangrove crabs are also reared in monoculture in mangrove cages and pens, or in polyculture with milkfish in extensive ponds (where mangroves used to thrive). The paper describes a SEAFDEC Aquaculture Department study to evaluate the effects of mud crab net pen systems on mangrove macroflora, and the replacement of dietary trash fish with low-cost pellets. Results showed that incomplete, low-cost pellets can replace fish biomass requirement in mud crab diets, but that crab presence resulted in fewer mangrove seedlings and saplings. Economic analysis showed the viability of crab culture in mangrove pens using a combination of fish biomass and pellets to reduce the requirement for (low-value) fish, which is a food item of poor coastal communities.
  • Book | Conference publication

    Philippines: In the forefront of the mud crab industry: Proceedings of the 1st National Mud Crab Congress 

    ET Quinitio, FD Parado-Estepa & RM Coloso (Eds.) - 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

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