Now showing items 1-13 of 13

    • Article

      Culture and economics of wild grouper (Epinephelus coioides) using three feed types in ponds 

      I Bombeo-Tuburan, EB Coniza, EM Rodriguez & RF Agbayani - Aquaculture, 2001 - Elsevier
      The performance of wild Epinephelus coioides juveniles was compared by feeding with live tilapia juveniles, fish by-catch, and formulated diet for 5 months in grow-out ponds. To minimize cannibalism, the groupers were graded into small (BW=24.9±7.3 g), medium (45.8±5.7 g), and large (84.1±30.0 g) size groups as block in a Randomized Complete Block Design (RCBD) and reared in nine 350-m2 ponds. To supply the tilapia juveniles, adult tilapia were grown 2 months prior to stocking of grouper at a rate of 15 tilapia/grouper. Grouper fed by-catch were significantly higher (P<0.01) than the other treatments in terms of final length and total production. The quality of by-catch could be gleaned by its efficient feed conversion ratio (FCR) of 1.0 (dry basis), significantly better (P<0.01) than the formulated diet that had an FCR of 2.8. Using by-catch, 47% of the harvest weighed >400 g and only 14% was classified <200 g. The cost of juvenile grouper and feeds represented 88–89% of the total investment in all treatments. Economic sensitivity analysis showed that a combination of improvement in factors such as price of grouper juveniles, feeds, yield, survival, and FCR would result in higher return-on-investment (ROI). When cost and returns were considered, feeding juveniles with by-catch was more profitable because it resulted in net income of Php 361,623/ha/year, an ROI of 155%, and a payback period of 0.4 year. The results clearly show that these economic indicators appear to be attractive, thus making grouper pond culture using by-catch a viable industry. More research efforts should, however, be directed towards developing a cost-effective formulated diet for the grow-out culture of E. coioides.
    • Article

      Culture of Scylla serrata megalops in brackishwater ponds 

      EM Rodriguez, ET Quinitio, FD Parado-Estepa & OM Millamena - Asian Fisheries Science, 2001 - Asian Fisheries Society
      Three- to five-day old hatchery-reared megalops (4.0 to 6.4 mg body weight) of the mud crab, Scylla serrata, were cultured to the juvenile stage in 20 m2 net cages installed in brackishwater nursery ponds. To establish a suitable stocking density, megalops were stocked at 10, 20, and 30 ind·m-2 in net cages. Treatments were replicated three times over time. After 30 days of culture, mean survival of juveniles ranged from 48.3 to 53.3% and did not vary significantly (P > 0.05) among the three stocking densities. Similarly, the mean final body weights of juveniles ranging from 2.91 to 3.40 g and mass weights 458.9 to 1066 g did not significantly differ among stocking densities. These results show that stocking of crab megalops directly in net cages in a brackishwater pond is feasible at any of the stocking densities tested.
    • Article

      Diet and harvesting regimen for the production of mud crab Scylla olivacea in brackish water ponds 

      EM Rodriguez, AT Triño & M Minagawa - Fisheries Science, 2003 - Japanese Society of Fisheries Science
      The effects of diet (fish bycatch or a mixed diet of 75% brown mussel flesh and 25% cooked cracked corn) and harvesting regimen (bimonthly selective harvesting, or single terminal harvesting) on growth, survival and production of mud crab Scylla olivacea (Herbst) in brackish water ponds were determined in a replicated factorial experiment. The crabs were stocked at 0.6 individuals per m2 for 118 days. There was no significant interaction (P > 0.05) between the diet and harvesting regimen treatments. Regardless of diet, the survival rate and net production of mud crabs were significantly higher (P < 0.05) when crabs were subjected to bimonthly selective harvesting than at single terminal harvest. Comparative cost–return analysis showed that bimonthly selective harvesting and mixed diet treatments attained higher net return and return on investment, and lower cost of production than the other treatments. Partial budgeting analysis showed that bigger profits can be earned by using a bimonthly selective harvesting and a mixed diet of 75% fresh or fresh-frozen brown mussel flesh and 25% cooked cracked corn.
    • Article

      Evaluation of hatchery-based enhancement of the mud crab, Scylla spp., fisheries in mangroves: comparison of species and release strategies 

      MJHL Lebata, L Le Vay, ME Walton, JB Biñas, ET Quinitio, EM Rodriguez & JH Primavera - Marine and Freshwater Research, 2009 - CSIRO Publishing
      Ranching, stock enhancement and restocking are management approaches involving the release of wild or hatchery-bred organisms to enhance, conserve or restore fisheries. The present study, conducted from April 2002 to November 2005, evaluated the effectiveness of releasing wild and hatchery-reared (HR) mud crabs in the mangroves of Ibajay, Aklan, Philippines where preliminary studies demonstrated declining fishery yields, abundance and size of crabs. Comparison of survival and growth of wild-released and HR Scylla olivacea and HR Scylla serrata demonstrated the effect of nursery conditioning, size-at-release and species differences. Overall yield and catch per unit effort (CPUE) increased by 46% after stock enhancement trials. Recapture rates of released crabs were highest in wild-released S. olivacea and in crabs measuring 65.0–69.9 mm carapace width (CW) and lowest in non-conditioned HR S. serrata. Growth rates were highest for conditioned HR S. olivacea and lowest for conditioned HR S. serrata (11.7 and 3.7 mm month-1 respectively). Fishing mortality was highest for S. olivacea, whereas natural mortality was greater for S. serrata. Conditioning hatchery-bred animals before release is also important in obtaining higher survival. S. olivacea was the more appropriate of the two species for release in mangrove habitats inundated with low-salinity water. However, there is a need for site-specific studies to evaluate the effectiveness of releases.
    • Article

      Extension of nursery culture of Scylla serrata (Forsskål) juveniles in net cages and ponds 

      EM Rodriguez, FD Parado-Estepa & ET Quinitio - Aquaculture Research, 2007 - Blackwell Publishing
      To address the preference of mud crab farmers for larger size Scylla serrata juveniles (5.0–10 g body weight or BW; 3.0–5.0 cm internal carapace width or ICW), a study was conducted to compare the growth and survival of crab juveniles (2.0–5.0 g BW; 1.0–3.0 cm ICW) produced a month after stocking of megalopae in net cages when reared further in net cages installed in earthen ponds or when stocked directly in earthen ponds. In a 3 × 2 factorial experiment, three stocking densities (1, 3 and 5 ind m−2), two types of rearing units (net cages or earthen pond) were used. Megalopae were grown to juvenile stage for 30 days in net cages set inside a 4000 m2 brackishwater pond and fed brown mussel (Modiolus metcalfei). Crab juveniles were then transferred to either net cages (mesh size of 1.0 mm) or earthen ponds at three stocking densities. After 1 month, no interaction between stocking density and rearing unit was detected so data were pooled for each stocking density and rearing unit. There were no significant differences in the growth or survival rate of crab juveniles across stocking density treatments. Regardless of stocking density, survival in net cages was higher (77.11±6.62%) than in ponds (40.41±3.59%). Growth, however, was significantly higher for crab juveniles reared in earthen ponds. The range of mean BW of 10.5–16.0 g and an ICW of 3.78–4.33 cm obtained are within the size range preferred by mud crab operators for stocking grow-out ponds.
    • Book

      Grouper culture in brackishwater ponds 

      DD Baliao, MA de los Santos, EM Rodriguez & RB Ticar - 1998 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 24
      Groupers (Epinephelus) are cultured in the Philippines using tiny fry and juveniles caught from the wild. A SEAFDEC/AQD technology verification study on grouper pond grow-out culture resulted in high productivity and profitability, indicating that grouper culture could become another income source for the country. This aquaculture extension manual is intended as a guide for fishfarmers and aquaculturists, extensionists, and students of aquaculture. It covers the following areas: What are groupers?; Commercially important groupers; Source of fry or fingerlings; Common collection gears for fry/juveniles; Brackishwater pond culture -- pond specifications, site selection, pond preparation, nursery operation, grow-out culture, harvest, post-harvest; Growth, survival and feed efficiency performance of grouper reared in brackishwater pond; Economics; Marketing and transport; and, Diseases.
    • Article

      Mud crab fattening in ponds 

      AT Triño & EM Rodriguez - Asian Fisheries Science, 2001 - Asian Fisheries Society
      Two independent experiments on mud crab (Scylla serrata, Portunidae) fattening were conducted simultaneously in 150 m2 ponds for 30 days: Expt. I - monosex male (286 ± 1.2 g) vs. monosex female (267 ± 0.9 g) stocked at 0.5·m-2, and Expt. II - monosex male (338 ± 3.1 g) or female (338 ± 2.8 g) vs. mixed sex (338 ± 3.4 g) stocked at 0.25·m-2. The crabs were fed daily a mixed diet of 75% brown mussel flesh and 25% fish bycatch at 10% of the crab biomass. Intermolt full male crabs weighing ≥ 400 g and roed females ≥ 350 g were partially harvested from the ponds after 20 days of culture using lift net and current method. Results of partial harvest from all treatments in both experiments showed a total yield of 51-55% of the total initial number of stocked crabs (450 crabs in Expt. I, and 338 crabs in Expt. II). From this partial harvest, crabs in Expt. I attained a mean final body weight of 496 g, a specific growth rate (SGR) of 2.75% in males and 432 g, SGR of 2.4% in females. Expt. II gave a mean final body weight of 520 g (males), 484 g (females), and 517 g (mixed sex) and SGR of 1.1, 0.73 and 0.81, respectively. Results of total harvest showed that the overall mean final body weight (372 ± 4.5 g) of monosex male crabs in Expt. I was significantly higher (P < 0.05) than monosex females. However, specific growth rate, carapace length and width, survival, and production were not significantly different (P > 0.05) between monosex males and females. On the other hand, growth and production of monosex crabs in Expt. II was not significantly different (P > 0.05) from mixed sex crabs. However survival of monosex crabs (100%) was significantly higher (P < 0.05) than mixed sex crabs (87 ± 1.88%).
    • Book

      Mud crab nursery in ponds 

      ET Quinitio, E Rodriguez, RF Agbayani, B Juanga, D Baticados, M Catacutan & R Bombeo - 2010 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 47
      An extension manual that is highly illustrated, detailing the biology, nursery, harvest, marketing, costs-and-returns of mudcrab nursery in ponds.
    • Book


      AT Triño, EM Rodriguez, EB Coniza & BP Juanga - 1999 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension manual; No. 27
      A 32-page manual that gives a general overview of mudcrab species of commercial value and their grow-out monoculture in ponds; polyculture with milkfish; and fattening in ponds, mangroves, and cages.
    • Article

      Nursery rearing of Penaeus monodon (Fabricius) using suspended (hapa) net enclosures installed in a pond 

      EM Rodriguez, I Bombeo-Tuburan, S Fukumoto & RB Ticar - Aquaculture, 1993 - Elsevier
      The use of suspended (hapa) nets as nursery enclosures for shrimp fry was tested. In the first trial, four stocking densities (72, 144, 288, and 432 fry m−3) of P. monodon fry (PL20, body weight = 8 mg, body length = 12.6 mm) were evaluated in 1×1×1.5 m hapa nets. Results showed that shrimp BW, BL, and survival rates were inversely related to stocking density. Shrimp fry stocked at 72 fry m−3 attained significantly greater BL of 22 and 37 mm and BW of 50 and 260 mg after 15 and 30 days, respectively, and survival of 92%. A verification trial using PL28 (BW = 10 mg, BL = 13.2 mm) at a stocking density of 288 fry m−3 in hapa nets of 2×3×1.5 m yielded a mean survival of 97%, BL 48.1 mm, and BW 780 mg. Hapa nets are therefore useful as alternative shrimp fry nursery systems in the absence of specialized tanks or pond nursery facilities.
    • Article

      Pen culture of mud crab Scylla serrata in tidal flats reforested with mangrove trees 

      AT Triño & EM Rodriguez - Aquaculture, 2002 - Elsevier
      Growth and survival of mixed sex mud crabs Scylla serrata (Forskal), held in 200 m2 pens located in reforested mangrove tidal flats, were evaluated. The effects of stocking density (0.5 or 1.5 m−2) and feed (salted fish bycatch or a mixed diet of 75% salted brown mussel flesh and 25% salted fish bycatch) were determined in a replicated factorial experiment. Duration of the experiment was 160 days. There were no significant differences (P>0.05) in growth, apparent feed conversion ratio (FCR), survival, and production among the two types of feed. Regardless of feed, the mean±SE FCR of 5.30±0.34 and survival of 56.00±1.90% at 0.5 m−2 stocking density were significantly better (P<0.05) than at 1.5 m−2 stocking density (7.6±0.63 FCR and 33.00±3.61% survival). However, growth was not significantly affected by stocking density. Cost–return analysis on a per crop per 200 m2 basis showed that the use of either of the two stocking densities with either diet was economically viable with a return on capital investment of 49–68%. However, crabs stocked at 1.5 m−2 and fed a mixed diet of 75% salted brown mussel flesh and 25% salted fish bycatch is more profitable. The integration of crab aquaculture within natural mangroves is therefore feasible in the Philippines, providing both immediate and long-term commercial and environmental benefits.
    • magazineArticle

      Seed production of mud crab Scylla spp. 

      ET Quinitio, FD Parado-Estepa & E Rodriguez - Aquaculture Asia, 2002 - Network of Aquaculture Centers
      Mud crab farming is an important source of income for fish farmers in the Philippines. The expanding export market for mud crab as an alternative for shrimp has led to intensified collection of wild seed for grow-out and has threatened the wild stocks. To ensure the sustainability of crab farming and reduce the fishing pressure on wild stocks, the SEAFDEC Aquaculture Department developed a technology for large-scale production of juvenile mud crabs, Scylla serrata (giant mud crab), S. olivacea (orange mud crab) and S. tranquebarica (purple mud crab).
    • magazineArticle

      Seed production of the crucifix crab Charybdis feriatus 

      FD Parado-Estepa, ET Quinitio & EM Rodriguez - Aquaculture Asia, 2002 - Network of Aquaculture Centers