Now showing items 1-12 of 12

    • Meeting report

      Capacity of mangroves to process shrimp pond effluents. 

      JH Primavera - 2004 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Shrimp culture has been criticized for causing mangrove loss and discharging effluents laden with chemicals, organic matter and nutrients into waterways. Hence the SEAFDEC Council mandated SEAFDEC/AQD to undertake studies that integrate aquaculture with mangroves. Thus, the Mangrove-Friendly Shrimp Culture Project follows two models: (a) the use of mangrove forests as filters to process effluents from intensive culture ponds, and (b) aquasilviculture which integrates low-density culture of crabs, etc. with mangroves. Worldwide only a few projects to date have tested mangroves as nutrient filters, hence the need to focus on this property of mangroves.
    • magazineArticle

      Environment-friendly schemes in shrimp farming 

      DD Baliao - SEAFDEC Asian Aquaculture, 2002 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Conference paper

      Environmental concerns and strategies for sustainable aquaculture. 

      N Sumagaysay-Chavoso - In Fishlink 2001, 29-31 May 2001, Iloilo City, Philippines, 2001 - University of the Philippines Aquaculture Society, Inc
    • magazineArticle

      Grouper culture 

      MB Surtida - SEAFDEC Asian Aquaculture, 1999 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Article

      The hydraulic control structure: A threat to the fishpen industry in Laguna de Bay. 

      BH Nielsen, AE Santiago & F Petersen - Likas Yaman, Journal of the Natural Resources Management Forum, 1981 - Natural Resources Management Center
    • Article

      Limnological notes on the finfish production problem of Laguna de Bay. 

      AE Santiago - Natural and Applied Science Bulletin, 1988 - College of Arts and Sciences, University of the Philippines
      Environmental problems have significantly affected fishery production and management in Laguna de Bay, the largest lake in the Philippines. Fishermen and fishpen operators are complaining about the slow growth of fish and low yields in the lake. In the 70’s two croppings were possible in fishpens since it took only 3 to 4 months then rear milkfish from fingerlings to marketable size (Felix, 1976). But in the early 80’s, stocked fingerlings attained a marketable size of about 200 g after 8 to 15 months (LLDA, 1983). In 1973 when the total fishpen area was only 5,000 ha, the annual harvest was 4 metric tons (MT)/ha. When fishpens covered 31,000 ha of the lake area in 1982, the annual yield dropped to 2 MT/ha (Centeno et al., 1987). Furthermore, the total open water catch of nearly 83,000 MT in the early 60’s (Rabanal et al., 1964) was reduced to one-fourth in the 80's.

      While the big drop in yield has been largely attributed to the proliferation and mismanagement of fishpens, over-exploitation of lake resources, and seasonal changes in the productivity of the lake (Centeno et al., 1987), the author attributes the present crisis basically to a lack of understanding o the basic ecological attributes of Laguna de Bay and their relation to fish growth and production. This paper is a brief commentary on the Limnological characteristics of Laguna de Bay tat are quite important in finfish production.
    • Article

      Mangroves and shrimp pond culture effluents in Aklan, Panay Is., central Philippines 

      JH Primavera, JP Altamirano, MJHL Lebata, AA delos Reyes Jr. & CL Pitogo - Bulletin of Marine Science, 2007 - University of Miami, Rosenstiel School of Marine and Atmospheric Science
      The capacity of a natural mangrove system in Ibajay, Aklan province, central Philippines to process shrimp pond culture effluents was assessed through analysis of mangrove community structure and 24-hr monitoring of water quality parameters (NH3-N, NO3-N, PO4-P, sulfide, and total suspended solids). Results from the latter showed decreased nutrient levels within 6 hrs after daytime draining of effluents into the mangrove stand, but only nitrate reduction was statistically significant. Based on nitrate loss, volume of water drained, mangrove area, and shrimp farming data (e.g., N loss from ponds, feed composition, feeding rate), calculations show that 1.8–5.4 ha of mangroves are required to remove nitrate wastes from 1 ha of shrimp pond. N uptake by the mangrove macroflora was supported by data showing longer nipa palm leaflets and faster mangrove seedling growth in the experimental mangrove receiving effluents compared to a control mangrove, but not from mangrove biomass measurements. These results have significant implications for the Philippine brackishwater pond culture industry to conserve or rehabilitate mangroves as potential pond biofilters, to implement legally mandated 20- and 50-m greenbelts, and to reverse the national 0.5 ha mangrove: 1.0 ha pond ratio.
    • Conference paper

      Practical water chemistry for fishfarmers I. Teaching strategies 

      JM Ferriols-Pavico, AC Gonzal & EV Aralar - In R Hirano & I Hanyu (Eds.), , 1990 - Asian Fisheries Society
      Years of ambitious, yet seemingly futile, efforts by the authors in the Philippines in making fishfarmers comprehend and appreciate chemical reactions the way chemists do, paved the way for the formulation of teaching strategies that communicate water chemistry. Theoretical concepts, being well understood, served as a springboard for farmers in translating abstract ideas into field situations. Laboratory practicals become less intimidating as standard laboratory glasswares and material were replaced by day to day material within the farmer s easy reach.
    • Meeting report

      Promotion of mangrove-friendly shrimp aquaculture in Southeast Asia. 

      Sulit, Virgilia T. - 2004 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This publication comprises two major parts : Report on the Regional Seminar-Workshop on Mangrove-Friendly Shrimp Aquaculture, Bangkok, Thailand, 24-27 June 2003 ; Report on the Mangrove Friendly Shrimp Culture Project: Phase I (2000-2003).
    • Conference paper

      Research on marine and freshwater fishes 

      AC Emata - In TU Bagarinao & EEC Flores (Eds.), Towards sustainable aquaculture in Southeast Asia and Japan: Proceedings of the Seminar-Workshop on Aquaculture Development in Southeast Asia, Iloilo City, Philippines, 26-28 July, 1994, 1995 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Most of the fish research at SEAFDEC AQD in 1992-1994 was on milkfish. Studies were conducted on year-round spawning through hormonal or environmental manipulation; optimum lipid and protein levels and ration size for captive broodstock; and the influence of spawner age on reproductive performance. The economics of hatchery operations, alone or integrated with broodstock as a commercial enterprise, was assessed. Mass production of larvae was refined with the use of commercial or SEAFDEC-formulated larval diets. Alternative rearing schemes in large tanks and ponds were tried. Hatcheryproduced and wild-caught larvae were compared in terms of growth and production in experimental nursery and grow-out ponds. Supplemental diets for brackishwater grow-out culture were formulated.

      Studies on broodstock management of grouper Epinephelus spp. included lipid enrichment of the diet and hormonal induction of sex inversion. Seed production techniques were developed but survival rates were low. Grouper culture was found economically feasible in experimental ponds with 'trash' fish as feed.

      The mangrove red snapper Lutjanus argentimaculatus was successfully induced to spawn with injection of human chorionic gonadotropin. Initial larval rearing trials were successful but survival rates must be improved.

      Hormonal manipulation of spawning of the Asian sea bass Lates calcarifer allows seed production during most of the year. Photoperiod manipulation leads to maturation of females, but not males, beyond the natural breeding season (April-November). Nursery rearing of 9 mm juveniles is feasible in floating net cages with night lights that attract food zooplankton. The requirements of sea bass for lipid, protein, carbohydrates, and essential amino acids were determined.

      In the rabbitfish Siganus guttatus, weekly injections of luteinizing hormone releasing hormone analogue (LHRHa) sustains milt production for three weeks. Thyroid hormones injected into broodstocks improved the growth of larvae to day 7.

      Induced spawning techniques for the Asian catfish Clarias macrocephalus were refined by determining the seasonal responsiveness to LHRHa and pimozide injections and testing for pheromonal induction of spontaneous spawning. The optimum insemination rate was determined and egg hatchability was enhanced by removal of the adhesive coat before incubation. Several practical diets for catfish during grow-out culture were tested against 'trash' fish.

      The broodstock management for bighead carp Aristichthys nobilis was studied. Cage-reared juveniles from cage-reared broodstock showed the best growth. To improve the reproductive performance, the broodstock diets were supplemented with vitamins A, C, and E.

      Research on tilapias focused on genetics and strain selection. Several strain testing procedures for Nile tilapia were evaluated in their efficiency to detect economically important strain differences. Reference lines were developed from two existing red tilapia strains to measure and reduce the effects of uncontrolled nongenetic variables in strain evaluation experiments with Nile tilapia. The tolerance of two Nile tilapia strains to heavy metals was similar when gauged by the 24-hour and 96-hour lethal concentration and by fish growth, survival, and reproductive performance. In a separate study, four strains of red tilapia showed generally higher seed production when reared in tanks than in cages. Improvements in the feed and feeding management for Nile tilapia were also studied.

      Intensive tilapia farming and feeding have led to oxygen depletion and fish kills in Sampaloc Lake. To rehabilitate the lake, it is imperative to reduce the farming area from 30 to 6 hectares; stop the use of commercial feeds; and remove the water hyacinths and other debris. Fish kills in Laguna de Bay have also become serious in recent years, and a review of the occurrences, losses, and possible causes is currently being conducted. Studies on the epizootic ulcerative syndrome of snakeheads in Laguna de Bay have yet to pinpoint the pathogen. Skin lesions in tilapias in several ponds and lakes in the country were found to be due to bacteria.
    • magazineArticle

      Shrimp culture: a global overview 

      WG Yap - SEAFDEC Asian Aquaculture, 1999 - Aquaculture Department, Southeast Asian Fisheries Development Center
    • Oral presentation

      Water quality criteria for farming the grass shrimp, Penaeus monodon. 

      HC Chen - In Y Taki, JH Primavera & JA Llobrera (Eds.), Proceedings of the First International Conference on the Culture of Penaeid Prawns/Shrimps, 4-7 December 1984, Iloilo City, Philippines, 1985 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Physiological and growth effects of pH, salinity, temperature, heavy metals, pesticides and others on juvenile grass shrimp Penaeus monodon have been investigated to

      determine the biologically safe concentrations. Optimal pH, salinity and temperature are found to be in the range of 8.0-8.5, 15-25 ppt, and 28-33°C, respectively. A dissolved oxygen concentration of 3.7 ppm seems to be the critical oxygen pressure to support the normal life of grass shrimp. To avoid poor survival and retarded growth, the recommended level for each pollutant are: heavy metals, 0.0025 ppm Hg, 0.1 ppm Cu, 0.15 ppm Cd, 0.25 ppm Zn; pesticides, 0.0004 ppb parathion, 0.001 ppb malathion, 0.008 ppb rotenone, 0.01 ppb Azodrin, 0.033 ppb Saturn, 0.01 ppb paraquat, 0.01 ppb Endosulfan, 1 ppb Butachlor; surfactants, 0.1 ppm Dunall OSE, 0.2 ppm BP 1100, 0.5 ppm Seagreen 805; and others, 0.033 ppm H2S, 0.1 ppm NH3.