Ministry of Agriculture & Rural Development 002/05/VIE Technical and economic feasibility of applying the Better Management Practices (BMP) to household aquaculture in Vietnam MS2: BMP PROTOCOL REPORT Nguyen Van Quyen, PhD (1), Nguyen Xuan Suc, MSc (1), Mai Van Ha, MSc (1) Le Van Khoa, PhD (1), Dinh Van Thanh (1), Virginia Mosk, MSc (2) (1): Research Institute for Aquaculture No.1 (2): Animal Biology, University of Western Australia May, 2007 I. POND PREPARATION 1.1 Pond condition The area of semi-intensive pond should be from 0.5-0.7 ha, with well- constructed and separated inlet and outlet. Pond bottom should slope down to outlet. 1.2 Pond cleaning Before PL (Post-larva) releasing 25-30 days, draining out pond water and drying pond bottom from 7-10 days. Ploughing pond bottom after removing mud top-layer. If acidic bottom, repeating water flushing 2-3 times. Ploughing on dry soil using tractor If can not drying pond bottom due to natural condition, wet cleaning method should be applied. Using pump to drain pond bottom then using high pressure pump to remove mud top-layer. If acidic bottom, repeating water flushing 2-3 times. Removing mud layer manually 1.3 Pond liming Use of CaO and CaCO 3 in the ratio of 2:1 for disinfection and bottom pH increasing. Pond bottom needs wetting and pH checking before lime application in order to experience of lime effectiveness and right application amount. Refer to below table as a reference pH bottom soil CaO/ha CaCO 3 /ha >6 1000 500 5-6 2000 1000 <5 3000 1500 Lime application to pond bottom 1.4 Water supplying Water before pumping into culture pond needs filtering and treating within reservoir using permitted chemicals and probiotics. Use of net bag fixed at 2 sides of pipe (small mesh size) for water filtering, discarding unwanted foreign objects and predators from ponds. Suitable water depth is at least 1.0 m. Water filtration by twin bag filter 1.5 Water color inducting About 10 -15 days before stocking, water color induction needs to be implemented using inorganic fertilizer. For example application: - A complex of Nitrogen and Phosphorus in the ratio of 2:1 dosing 20-30 kg/ha water surface. - Utilization of NPK (3:5:1) dosing 20- 30 kg/ha. If water coloration fails 3-4 days after fertilization, an additional application of 3-5 kg/ha to get desired water color soon. Ideal green colored water after fertilization 1.6 Community involvement In the step of pond preparation, involvement of community can be as followings: - An agreement on culture time, pond preparation, wise water tide and pumping. - Well-planed pond bottom cleaning, avoiding negative impact onto wide community. - Cooperation in buying shrimp pond- purposed materials and equipment like lime, fertilization, probiotics so that pond management and operation expenses will be minimize (price negotiation, feed transportation) and maximize benefit as a result. II. POST-LARVA SELECTION AND STOCKING 2.1 Post-larva selection Choosing a prestige PL production station with certified quality of PL granted. PL buyer should come to supplier early to learn and study origin and condition of PL that is to be bought. Observations should be made on activity, color, size, etc. from the selected tanks in the hatchery. The post larvae should be uniform in size with relatively uniform body color and should be actively swimming against the swirling water current produced in a round tub. PL batch should be bred from one brooder, not to be graded (physical damage avoided). A PL15 should have a critically suitable body length of 12 mm, if not, PL is recognized to be stunt and poor quality. Healthy and active PLs uniform size Good color of PL should be ashy grey or bright transparency, telson should open when swimming, clean appendices while poor PL will appear to be milky white. 2.2 Some suggested practices for PL quality checking 1) When stop aeration PLs will jump out of water surface, get some PLs into bucket and swirling manually water in order to create mediate water current, good PLs will stay in the bottom and swim counter clock wise with water movement while weak PLs will concentrate in the central of bucket- reject this PL batch 2) Formalin concentration of 100 ppm and the PL should be treated for above 30 minutes. It is essential that water in the tank is well aerated; ideally using oxygen cylinders. After this treatment the water is stirred to concentrate all the dead and weak seeds at the center- bottom of the tank. 3) Formal sock: using 100 PLs into white color bucket with 10 liter water mixed with 2 ml formalin and aeration. Giving an observation within 30 minutes for mortality, if it is more than 10 PLs the batch is in poor quality. 4) Freshwater sock: Getting 40 PLs into a container with the nursery- origined water, then adding the same volume of fresh water into the container (ratio of 1:1). Giving an observation within 60 minutes for mortality, if it is more than 10 PLs the batch is in poor quality. 5) PCR testing: Sampling 30 PLs into a prepared nylon bag (good water with well-aerated), then transfer to Lab as soon as possible for PCR and MBV checking. Consulting PCR expert and technician for the quality of tested PLs. 1.3 Stocking Suitable time for PLs stocking into pond is 5-6 am or 5-6 pm. PLs should also have to be acclimatized to pond water conditions like salinity and temperature with gradual addition of pond water to the tank. Acclimatization of seeds to pond water Temperature conditioning by gradually pouring pond water onto PL bags, then put these bags into the ponds within 10 minutes prior to releasing as long as temperature is equal in between in bag and out pond. It is suggested that salinity in PLs nursery station and ponds should be similar in value, the difference should not be more than 5 ppt. Salinity adaptation needs conducting by slowly adding pond water into PL bags or putting al already temperature-adapted in a big container and adding gradually pond water accordingly. 2.4 Stocking density Stocking density will completely depend on investment and technical know-how capacity of household. However, suggested stocking densities as given below: Stocking density (PL15/m 2 ) Expected productivity (kg/ha/vụ) 10 - 25 3000 kg 25 - 30 4500 kg 30 - 40 6.000 kg 2.5 Community- based management - Making groups for selecting and purchasing PLs, gathering PLs prior to PCR and MBV testing - Concentrate PLs transportation and acclimatization. - Production grouping gives more advantage with regard to price bargain and PL quality. III. POND, ENVIRONMENT AND DISEASE MANAGEMENT 3.1 Water quality management To void acute change of temperature and shock to the animals, try to maintain pond water level at least 1 m (ideal suggested is 1.2-1.5m). Pond water with a healthy phytoplankton bloom is green. Suitable transparency of pond water phytoplankton is 30 - 40 cm. If transparency is greater than 40 cm, exchange 20% of pond water and then inorganically fertilize 20 - 30 kg/ha. If transparency is less than 30 cm, exchange 20 - 30% of water volume. If water color is dark and has low transparency caused by dead algae, exchange 20-30% water volume (using reservoir water) till color improved and lime using CaCO 3 at a dose of 50-100 kg/ha. Black color water (poor quality) Do not use any tool or facility (net, boat, etc.) in more than one pond, in order to avoid disease cross-contamination. If you must share these tools, it is necessary to disinfected or clean and then dry for at least one day. Poor pond management Clear pond water indicates poor algae community. Supplement fertilization using phosphate at a dose of 2-3 kg/ha every 2-3 days till getting desired color. Good Bad Water color as an indicator for quality 3.2 Use of Paddlewheels Paddlewheels should be used for a semi- intensive shrimp culture pond in order to increase dissolved oxygen and decrease toxic gases (H 2 S, NH 3 , etc.). If pond area is 0.5 ha and stocking density is 20 PL/m 2 , 4 paddlewheels, with 8 propellers total, should be used. Generally, aerators should be placed to maximize circulation throughout the pond and to avoid leaving any dead areas. Time table for paddlewheel use is below: Shrimp age (week) Paddle-wheel using 1 – 4 4h30 - 5h30 4 – 6 2h - 5h30; 17h - 18h 7 – 11 2h-5h30; 8h30-9h30; 17h-18h; 20h30-21h30 12 – 14 0h-5h30; 8h30-9h30; 17h-18h; 2030-21h30 15 – harvest 23h-6h; 7h-9h; 16h- 18h; 19h30-21h30 3.3 Feeding In the first two months of culture period, it is a habit of shrimp to locate near shore, therefore feed should be casted within the area accordingly. From 3 th month onward feeding should be homogeneous all over pond surface, excluding dirty bottom area and too close to pond bank. Stopping aeration 30 minutes prior to feeding, checking feeding efficiency about 1 hr after feeding and re-operate oxygenation. Use of feeding tray to control feed Poor quality feed including commercial pellet is not advised to use, particularly home-made feed using poor quality materials like trash, crustacean as they can be water-polluted cause and disease infection. Bottom algae and floating lab-lab need manually removing using Keep examining feeding area for pollution condition, it is good if bottom layer is brown color or thin brown layer. Sludge on top soil layer of the pond bottom If bottom soil is black, try to feed offshore using distribution boat, reducing feeding rate within 2 days and exchanging water of 15-20 cm. If acidic soil or yellow water color observed, applying lime along pond bank before and after raining. Yellow water in acidic soil after raining In normal condition (no disease recorded), sampling some shrimp and observing feed fullness in gut 2 hrs after feeding, if not, apply more feed. Quantity of feed depending on quantity of shrimp in the pond. Normally, shrimp is smaller rate of feed is higher. Refer to below table as a reference Good Bad Shrimp size (g/shrimp) Rate of feed (%) 2 6.5 5 5.5 10 4.5 15 3.8 20 3.5 25 3.2 30 2.8 35 2.5 Good 3.4 Disease management Making note daily for abnormal shrimp health condition and syndrome, number of death and disease infected near by pond bank. Dead shrimp must be remove out of pond and treated correctly (bury them away from the ponds). Removal of dead shrimp from pond margin Netting 10 shrimp weekly to check cleanness of shell and gill. If dirtiness found applying offshore feeding, eliminating bloom algae using hand or net with small mesh size. If possible experiencing water exchange and liming with a rate of 200-300 kg/ha Shrimp with fouling on shell About 3-4 week after stocking if shrimp keeps swimming a long pond bank/edge, pond bottom should be checked whether bottom algae occurrence or black mud layer accumulation. If so, lessening feeding amount and frequency, exchanging water, dolomite or lime application. If disease infected and dead shrimp found nearby pond edge, cutting down feeding rate and replacing water at 15- 20 cm height, applying CaCO 3 powder or Dolomite (200-300 kg/ha). Shrimp with black gill disease If then high mortality in 2 consecutive days, considering emergency harvesting can be carried out. If White Spot Disease (WSD) recorded, not to discharge water and immediately inform neighboring pond owners. Check any abnormalities in water and soil condition and take immediate action to correct the problem. In case of dead shrimp found after raining, instantly liming pond water and banks, best practice is to apply lime before raining. Shrimp with WSD infection In early morning if swimming nearby pond edge, feeding and oxygenation need putting in to operation. 3.5 Community- based management Working in group to choose feed, probiotics and other materials supplier/seller so as to purchase them with suitable price, and lower transportation cost. Inter-supervising sanitation condition and environment protection attitude in term of waste water treatment, disease report and putting out. Timely report disease infection condition to wide community. Giving a capital assistance in disease control, management, and zoning. Sharing experience and technical know- how in shrimp pond management and operation. In cooperation with neighboring communities for the mission of water quality protection and management, disease control and quarantine. Farming in groups/communities may be economical by contribution in investing environment and disease monitoring devices like test kits, pH and DO meters, PCR kit. Community can also bring social atmosphere that motivate significantly culturists. 3.6 Frequently faced issues and its remedies 1) Low transparency (less than 30-40 cm): water exchange (20-30 %), application of Zeolite or Diatomite (5-10 kg/100m 2 ) 2) DO super-saturation (caused by algae bloom, sunny) that may cause air bubble disease: formalin spraying or using Na 2 S 2 0 3 (3-5 ppm). 3) To dispose of excess Chlorine or Ozone used for disinfection, using Na 2 S 2 0 3 at the rate of 3- 5 ppm 4) Water with low pH (< 7): use of CaO at the dose of 5-10 kg/100m 2 . 5) Water with high pH (>8.5): application of fine sugar 10-12 kg/ha, or drive water through bio- treatment system, or acid acetic produced by fermenting 10-15 kg rice bran in 1 m 3 pond water in 7 days (extract supernatant only). 6) Oil film can be eliminated and skimmed using clean cloths or inner part of maize 7) Temperature stratification (mainly caused by heavy rain): draining out top layer water, operating mixing devices, and then Zeolite or Dolomite applied. [...]...Community based-market can give an advantage in negotiation selling price and choosing right buyer, particularly when free disease shrimp produced IV HARVESTING AND MARKETING 4.1 Partial harvesting When reaching individual size of 2530 g If shrimp is not uniform in size use of grading device to catch wanted one 4.2 At once harvesting Drain out water for this method of harvesting Shrimp after smolting should... should not be experienced with harvesting due to soft shell 4.3 Post-harvesting preservation As soon as harvesting, shrimp have to washed and iced (ice/shrimp ratio is 1/1), transportation to processing unit directly 4.4 Critical role responsibility of community Community plays an important role in the production chain, from production preparation to product marketing . Ministry of Agriculture & Rural Development 002/05/VIE Technical and economic feasibility of applying the Better Management Practices (BMP) to household aquaculture in Vietnam. PLs the batch is in poor quality. 4) Freshwater sock: Getting 40 PLs into a container with the nursery- origined water, then adding the same volume of fresh water into the container (ratio of. repeating water flushing 2-3 times. Removing mud layer manually 1.3 Pond liming Use of CaO and CaCO 3 in the ratio of 2:1 for disinfection and bottom pH increasing. Pond bottom needs