Technical and economic feasibility of applying the Better Management Practices (BMP) to household aquaculture in Vietnam - MS2" potx

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 pressu

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 CaCO3 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 CaCO3/ha

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/m2)

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 CaCO3 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 (H2S, NH3, etc.) If pond area is 0.5 ha and stocking density

is 20 PL/m2, 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 3th 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

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 CaCO3 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/100m2)

2) DO super-saturation (caused by algae bloom, sunny) that may cause air bubble disease: formalin spraying

or using Na2S203 (3-5 ppm)

3) To dispose of excess Chlorine or Ozone used for disinfection, using

Na2S203 at the rate of 3- 5 ppm 4) Water with low pH (< 7): use of CaO

at the dose of 5-10 kg/100m2 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 m3 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

IV HARVESTING AND

MARKETING

4.1 Partial harvesting

When reaching individual size of

25-30 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 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 of community

responsibility

Community based-market can give an advantage in negotiation selling price and choosing right buyer, particularly when free disease shrimp produced Community plays an important role in the production chain, from production preparation to product marketing