Now showing items 1-3 of 3

    • Book

      Feeding prawns for grow-out culture 

      FP Pascual & RV Rivera - 1989 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension pamphlet / SEAFDEC. Aquaculture Department; No. 2
    • Book

      Recent developments in prawn pond culture 

      FD Apud - 1989 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension pamphlet; No. 1
      This document presents the recommended methodology, nominal projections and partial costs and returns, for extensive prawn culture at two production objectives, and semi-intensive culture with costs and returns breakdown for three production targets. Intensive prawn culture procedures are not discussed.

      Extensive Prawn Culture System I projects a production yield of about 110 to 160 kg/ha/crop or more in four months and survival rate of from 65 to 70%. The extensive Prawn Culture System II aims for a production rate of about 230 kg/ha/crop in four months at about 70% survival with expected average body weight of about 25 grams. The procedures indicated have been verified and are now widely practiced.

      Production targets under the Semi-intensive Prawn Culture System I range from 350 to 500 kg/ha in four months at survival rate of about 70 to 75% and expected average size at harvest of about 28 to 30 pcs/kg. This method has been confirmed at different collaborative sites using the modified SEAFDEC diet developed by the Feed Development staff of the SEAFDEC Aquaculture Department.
    • Book

      Recommended practices for disease prevention in prawn and shrimp hatcheries 

      GD Lio-Po, RD Fernandez, ER Cruz, MCL Baticados & AT Llobrera - 1989 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Aquaculture extension pamphlet / SEAFDEC Aquaculture Department; No. 3
      Disease in prawn is any abnormal condition which may affect adversely the appearance, growth, and function of the animal. It may or may not result in mortalities. Disease outbreaks occur commonly in different culture systems such as hatcheries and grow-out ponds.

      Disease develops through the interaction of the prawn (the host), the causal agent (the pathogen), and the environment. In the presence of a susceptible host, a pathogen and predisposing environmental conditions (poor water quality, inadequate food, frequent handling, overstocking), disease is very likely to occur. Improved environmental conditions, healthy prawns and absence of disease agents would therefore lessen the chance of a disease outbreak.

      The causal agents may be pathogenic organisms (viruses, bacteria, fungi, protozoa, helminths, microcrustaceans) or nonpathogenic adverse environmental conditions (extreme temperatures, low oxygen levels, chemical poisons). Living disease agents cause infectious disease which generally result in gradual mortalities. Non-living disease agents cause non-infectious diseases that result in sudden mass mortalities.

      The environment determines the balance between the prawn as host and the disease agent. Microorganisms are always present in the water and some of them cause disease only when the prawn has been weakened through exposure to stressful environmental conditions.

      Hatchery personnel should realize that they themselves could transmit disease through their contaminated hands, clothing, and footwear. Equipment such as water pumps, blowers, pipes, and materials such as scoop nets, water hoses, pails, glasswares are also possible carriers of disease agents. Spawners, live natural food like diatoms, rotifers and brine shrimp, and artificial diets could also be vehicles of disease transmission.

      The prawn culturist, thus, must be able to manage the environment and make it favorable for the prawn. Hatchery management should, therefore, include operation procedures that will reduce the possibility of disease development during larval rearing. This manual recommends practices for disease prevention to prawn hatchery operators and technicians.