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FARMING FRESHWATER PRAWNS
A manual for the culture of the giant river prawn
(Macrobrachium rosenbergii)
| FAO
FISHERIES
TECHNICAL
PAPER
428 |
The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of the Food and Agriculture Organization of the United Nations concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
ISBN 92-5-104811-8
All rights reserved. Reproduction and dissemination of material in this information product for educational or other non-commercial purposes are authorized without any prior written permission from the copyright holders provided the source is fully acknowledged. Reproduction of material in this information product for resale or other commercial purposes is prohibited without written permission of the copyright holders. Applications for such permission should be addressed to the Chief, Publishing and Multimedia Service, Information Division, FAO, Viale delle Terme di Caracalla, 00100 Rome, Italy or by e-mail to [email protected]
© FAO 2002
ABSTRACT
PREFACE
INTRODUCTION
CHAPTER 1.BIOLOGY
1.1 Names, natural range, and characteristics of freshwater prawns
Naming freshwater prawns (nomenclature)
The natural home of freshwater prawns (distribution)
Identifying Macrobrachium rosenbergii from other freshwater prawn species
1.2 The shape (external morphology) and other characteristics of freshwater prawns
1.3 Life history
1.4 Sources of further biological information
CHAPTER 2. SITE SELECTION
2.1 Hatcheries and indoor nurseries
Needs for good quality water
Deciding how much water is needed
Other requirements for hatchery sites
2.2 Outdoor nurseries and grow-out facilities
Choosing your site: topography and access
Choosing your site: climate
Choosing your site: soil characteristics
Choosing your site: power supplies
Choosing your site: fry and consumables
Choosing your site: labour
Choosing your site: sympathetic authorities
and technical assistance
CHAPTER 3.
BROODSTOCK
3.1 Obtaining and selecting egg-carrying females
Obtaining berried females
Genetic improvement
3.2 Holding your broodstock in temperate zones
3.3 Managing your broodstock
CHAPTER 4.
HATCHERY PHASE
4.1 Buildings and equipment facilities
Basic site and building requirements
Equipment and the distribution of water and air
4.2 Hatchery management
Water treatment
Starting your larval batch
Routine work
Feeding
Hygiene, health and management problems
Monitoring performance
The greenwater system of freshwater prawn culture
4.3 Harvesting postlarvae
CHAPTER 5.
POSTLARVAL HOLDING AND NURSERY PHASES
5.1 Basic requirements and facilities
Holding tanks
Indoor (primary) nursery facilities
Outdoor (secondary) nursery facilities
Nursery cages
5.2 Holding postlarvae before sale
5.3 Transporting postlarvae
5.4 Managing nurseries
Indoor (primary) nurseries
Outdoor (secondary) nurseries
Other systems
CHAPTER 6.
GROW-OUT PHASE
6.1 Site requirements and construction
Defining the pond
Supplying water to the ponds
Discharging water from the ponds
Aeration
Miscellaneous
6.2 Management of the grow-out phase
Size variation
Semi-intensive monoculture in tropical zones
Monoculture in temperate zones
Polyculture and integrated culture
6.3 Feeding and fertilization
Feed type
Measuring feed efficiency
Feeding rate
6.4 Health, predation and disease
Watching for signs of problems
Dealing with problems of predation
Coping with diseases and other problems
6.5 Monitoring performance and record keeping
CHAPTER 7.
HARVESTING AND POST-HARVEST HANDLING
7.1 Harvesting your market-sized prawns
Cull harvesting
Drain harvesting
7.2 Handling your prawns after harvest and ensuring good product quality
Handling prawns to be sold fresh
Handling prawns to be sold frozen
Handling for live sales
7.3 Code of practice for harvesting, processing
and handling prawns
CHAPTER 8.
MARKETING
8.1 Marketing your freshwater prawns alive
8.2 Marketing your freshwater prawns fresh or frozen
8.3 Marketing your freshwater prawns at your farm gate
8.4 International opportunities and general marketing strategy
ANNEXES
ANNEX 1.
Key to larval stages of freshwater prawns (Macrobrachium rosenbergii)
ANNEX 2.
Natural beach filter for seawater
ANNEX 5.
Production of farm-made larval feeds
ANNEX 6.
Stock estimation
ANNEX 7.
Seine nets
ANNEX 8.
Size management
ANNEX 9.
Farm-made pond feeds
ANNEX 10.
Basic code for introductions
ANNEX
11.
Glossary of terms, abbreviations and conversions
FINANCIAL CONSIDERATIONS
ACKNOWLEDGEMENTS
REFERENCES
TABLE 1
Body segments (somites) in Macrobrachium rosenbergii and appendage function
TABLE 2
CHARACTERISTICS OF WATER SUITABLE FOR FRESHWATER PRAWN HATCHERIES
TABLE 3
Artificial brackishwater (12 ppt) for M. rosenbergii hatcheries
TABLE 4
Diluting seawater and brine to make brackishwater for larval freshwater prawn culture
TABLE 5
Water quality requirements for freshwater prawn nursery and grow-out facilities
TABLE 6
Example of water requirements for ponds based on various assumptions
TABLE 7
Relationship between temperature, salinity and dissolved oxygen saturation levels (in ppm)
TABLE 8
Hatchery feeding schedule
TABLE 9
Alternative hatchery feeding schedule
TABLE 10
The major diseases known to affect freshwater prawns, and their exterior symptoms
TABLE 11
Prevention and treatment* of freshwater prawn diseases
TABLE 12
Water discharge capacity (in m3/hr) of concrete pipes under various pressure heads
TABLE 13
Sizes of outlet pipes for ponds with monks
TABLE 14
Time taken to drain ponds (in hours) with different drain pipe sizes
TABLE 15
Oxygen transfer efficiencies of basic types of aerator
TABLE 16
Lime requirements for treating the bottom of ponds between cycles
TABLE 17
Average stocking densities and yield of carps, tilapias and freshwater prawns reared in polyculture, based on a literature study
TABLE 18
Examples of major ingredients either used individually or in mixed freshwater prawn grow-out feeds
TABLE 19
Tentative specifications for semi-intensive freshwater prawn grow-out feeds
TABLE 20
General recommendations to restaurants and consumers for handling and storing freshwater prawns
BOX 1
Removal of iron and manganese
BOX 2
Flow-through requirements for ten 5 m3 larval rearing tanks
BOX 3
Grow-out water requirements
BOX 4
Numbers of berried females required
BOX 5
Activating biofilters
BOX 6
Treatment of brackishwater
BOX 7
Regular monitoring of larval water quality
BOX 8
Alternative larval stocking strategties
BOX 9
Recommendations for good larval water quality
BOX 10
Maintenance schedule for recirculation systemsin the morning:
BOX 11
Feeding bsn depends on tank volume, not the number of larvae in it
BOX 12
Additional recommendations for recirculation system hygiene
BOX 13
Notes on potential disease problems
BOX 14
Definitions of farming intensity used in this manual
BOX 15
Systems of management in grow-out ponds for freshwater prawns
BOX 16
Application of rotenone and teaseed cake
BOX 17
Measuring soil pH
BOX 18
Reasons for not applying organic fertilizers
BOX 19
Keeping rooted plants out of your ponds
BOX 20
Size grading
BOX 21
Polyculture of freshwater prawns with carps in China
BOX 22
Examples of integrated freshwater prawn culture in Viet Nam
BOX 23
Example of feeding rate for freshwater prawns
BOX 24
Examples of freshwater prawn (M. rosenbergii) growth and production rates
FIGURE 1
The external features of Macrobrachium rosembergii.
FIGURE 2
These very large Macrobrachium rosenbergii males were obtained
from a fisheries enhancement
programme (India)
FIGURE 3
How to sex juvenile Macrobrachium rosembergii.
FIGURE 4
Notice that the abdominal pleura of the two females with
this BC male Macrobrachium rosenbergii are enlarged to accommodate eggs (Brazil)
FIGURE 5
The major male morphotypes of Macrobrachium rosenbergii are called blue claw (BC), orange claw (OC), and small male (SM) (Israel)
FIGURE 6
The body shape of freshwater prawns (Macrobrachium rosenbergii) is different to that of penaeid shrimp, as these cross sections of the 5th abdominal segments show
FIGURE 7
Freshwater (caridean) prawns can also be distinguished from penaeid shrimp by looking at the second pleura on the abdomen (see arrow)
FIGURE 8a
Grow-out pond inlets need to be screened to exclude predators
FIGURE 8b
Screened inlets being used in this freshwater prawn grow-out pond (Peru)
FIGURE 8c
This type of inlet screen is used in Thailand, especially when ponds are filled by long-tail pump
FIGURE 9
Pumps can be powered by old diesel bus engines (Thailand)
FIGURE 10
More expensive pumps are used in some countries; this one is being used to harvest freshwater prawns (Hawaii)
FIGURE 11
The eggs of Macrobrachium rosenbergii are carried by the (‘berried’) females until they are ready to hatch; as they ripen, they change from orange to grey/black (Hawaii)
FIGURE 12
This hatching system consists of a 300 litre rectangular hatching tank and two 120 litre circular tanks, one for collecting larvae and one to house a biofilter
FIGURE 13a
Airlift pumps can be constructed in many different ways
FIGURE 13b
Airlift pumps keep the water moving and oxygenated (Peru)
FIGURE 14a
Small hatcheries can be very simply constructed (Peru)
FIGURE 14b
Interior of a simply-constructed inland hatchery for freshwater prawns (Thailand)
FIGURE 14c
Buildings are often rebuilt as the hatchery prospers but the structure remains simple
FIGURE 15
Partially covered larval tanks, made from concrete blocks (Thailand)
FIGURE 16
Hatchery layout is site specific; this is one example
FIGURE 17
This shows the water flow through a freshwater prawn hatchery recirculation system
FIGURE 18
There can be a lot of wasted space around circular tanks but none is wasted between these rectangular larval tanks
FIGURE 19
Inside of cylindrico-conical larval tank, showing the central standpipe used during water exchange (Brazil)
FIGURE 20
Some space can be saved by grouping tanks together but there is still some ‘dead’ space between these cylindrico-conical hatchery tanks (Brazil)
FIGURE 21
The water in these larval tanks recirculates through a shared filter (Brazil)
FIGURE 22
These larval rearing tanks have individual recirculation systems (Brazil)
FIGURE 23
Whatever kind of hatchery tank drain you use, it needs to be protected by a filter sock to prevent the loss of larvae during water-changing operations
FIGURE 24
Turn-down drains are the best way of changing water or harvesting hatchery tanks
FIGURE 25
Tanks for storing hypersaline water and freshwater, and for mixing purposes at an inland hatchery in Thailand; note the roof and side covers for excluding aerial pollution and controlling temperature
FIGURE 26
Installing a ring main air supply system using larger bore piping than you use to connect the main to each valve helps you to ensure that each tank receives the amount of air you wish it to have
FIGURE 27
Close-up of taps for brackishwater, freshwater and air supplies to larval tanks (Brazil)
FIGURE 28
Power supplies are not always reliable. Loss of aeration can quickly cause devastation in a hatchery. This hatchery has not only installed two electrically-driven blowers (one as a back-up) but has also provided a petrol engine so that the drive belts can be rapidly changed if the power fails (Thailand)
FIGURE 29
The water distribution and treatment system is site specific; this is one example
FIGURE 30
The water in physical hatchery filters may flow upwards or downwards; this illustrates an upward-flowing filter
FIGURE 31
Close-up of a biological filter shared between two larval tanks in Brazil, showing the water entering the mechanical filters (foreground), from where it passes through the biological filter and exits back to the two tanks by means of simple airlift pumps
FIGURE 32
There are many types of biological filters for hatchery recirculation systems; these are the most common types
FIGURE 33
Freshwater prawn larvae in tanks are difficult to see; using a white board will help
FIGURE 34a
Tanks need regular siphoning to remove faeces, the larval exoskeletons that are cast off during moulting, and waste food
FIGURE 34b
Good tank hygiene is essential for hatchery success (Hawaii)
FIGURE 35
Many of the larvae that go missing during the larval rearing cycles are not mortalities but are lost through operator error. For example, it is easy to lose larvae during water changing and tank cleaning. Losses can be minimized by filtering the water removed from tanks and returning the live larvae, if healthy
FIGURE 36a
A method of evaluating the quality of Macrobrachium rosenbergii larvae is illustrated in this diagram
FIGURE 36b
This form provides a convenient way of recording your observations on the quality of Macrobrachium rosenbergii larvae
FIGURE 37
Postlarval freshwater prawns can use a nylon screen as an additional surface area in holding tanks (Brazil)
FIGURE 38
Overhead air and water distribution systems are used to supply these indoor nursery tanks (USA)
FIGURE 39
Substrates can be used in nursery tanks to increase the surface area available to juvenile prawns; this substrate consists of the material used to make barriers around roadworks (USA)
FIGURE 40
The standpipe drain in this pond, normally vertical, is turned down to allow water to flow out (USA)
FIGURE 41
Postlarvae in plastic bags can be transported long distances in modified trucks provided with shelves, a small fan, and simple cooling
FIGURE 42
The substrate material shown dry in FIGURE 39 can be seen beneath the water surface in this nursery tank (USA)
FIGURE 43
Macrobrachium rosenbergii farms can be large (this one was 70 ha) but need careful production, marketing and business management for sustained success (Brazil)
FIGURE 44
The bottoms of grow-out and nursery ponds need to be sloped towards the drainage point and to be smooth; this increases the efficiency of both drain-harvesting and seine-harvesting
FIGURE 45
When you construct ponds in areas where the soil structure is less suitable, the banks will leak less if you bring clay from another site and use it to make an inner impervious core
FIGURE 46
Pond banks should have the proper angle of slope if you want to minimize erosion and cut down the costs of maintenance
FIGURE 47
The bank of this freshwater prawn pond is being eroded because its slope is too steep (Hawaii) The banks of these ponds have had grass turfs laid on them (Brazil)
FIGURE 48
The banks of these ponds have had grass turfs laid on them (Brazil)
FIGURE 49
Pond bank planted with coconut, grass, and banana; besides stabilising the bank this is a form of integrated farming (Thailand)
FIGURE 50
The dissolved oxygen levels of incoming pond water can be increased by rippling and cascading
FIGURE 51
Simple gravel filters on the water intake system help to minimize the predators in freshwater prawn ponds (Peru)
FIGURE 52
Design your water distribution system so that each pond has a separate supply and the discharge from each pond does not enter any other
FIGURE 53
Where the topography of the site makes it feasible, supplying water by gravity keeps the dissolved oxygen level high (Brazil)
FIGURE 54
Supplying water above the pond water level provides some oxygenation, while grass minimizes erosion of the bank (Brazil)
FIGURE 55
There are many different ways of controlling the water entering your ponds: these are some examples
FIGURE 56
The outlet structure, sometimes known as a ‘monk’, can be used to control the level of the water as well as to screen the water to prevent the loss of freshwater prawns (Brazil)
FIGURE 57
Most prawns will have been previously removed by seining; the rest are harvested not only at the drain but also by cast net (as shown in this photo from India) while draining proceeds.
FIGURE 58
This freshwater prawn pond has just been totally drained (Thailand)
FIGURE 59
Pond outlets need to be screened to prevent the loss of your prawns; this type of structure can be designed to hold screens and to control the flow rate
FIGURE 60
Long-tail pumps are easily available in Thailand
FIGURE 61
Long-tail pump being used to lift water from a Thai irrigation canal into a supply channel for freshwater prawn ponds (this type of pump can also be used to drain ponds by pumping)
FIGURE 62
Using paddlewheel aerators keeps the dissolved oxygen level high enough to increase stocking levels
FIGURE 63
Power supplies are not always reliable. Loss of aeration at a critical time of the day and/or when ponds are heavily stocked. This Thai farm is using a mobile engine to drive long-shaft aerators in two adjacent ponds
FIGURE 64
Long-shaft aerator in action (Thailand)
FIGURE 65
The sediment in continuously operated freshwater prawn ponds can become so deep that it reduces the water volume and depth and disturbs the drainage pattern; this pond had not been drained for many years (Hawaii)
FIGURE 66
The bottoms of ponds can be tilled with a disc harrow (USA)
FIGURE 67
There are some advantages in rearing freshwater prawns (Macrobrachium rosenbergii) to a larger (juvenile) size before stocking
FIGURE 68
Sudden changes in temperature and pH can cause mortalities when prawns are stocked. Before their release, the bags containing the postlarvae should be floated in your pond to bring the temperature within them gradually to that of the pond. Any adjustments to the pH of the transport water should have been made in the hatchery, before transport (Brazil)
FIGURE 69
When the temperature in the bag is the same as in your pond, the postlarval Macrobrachium rosenbergii can be released (Brazil)
FIGURE 70
Grass is invading the shallow areas of this pond (Brazil)
FIGURE 71
Close-up of material used as pond substrate for Macrobrachium rosenbergii culture (USA)
FIGURE 72
Substrates have been placed vertically in this temperate zone rearing pond for Macrobrachium rosenbergii culture (USA)
FIGURE 73
In this temperate zone rearing pond the substrates have been placed horizontally (USA)
FIGURE 74
Macrobrachium rosenbergii farming can be integrated with crop and other livestock production; in this case prawn culture is associated with rice culture and vegetable production (Viet Nam)
FIGURE 75
If hatchery-reared Macrobrachium rosenbergii are not available, brushwood can be used to capture wild postlarvae (Viet Nam)
FIGURE 77
Using a lift net for observing feed consumption (Puerto Rico)
FIGURE 76
Feed can be distributed within the pond by simple boats, which can be lifted from one pond to another; manual feeding along at least one side of the pond would be quite difficult in this case because of the method of construction, which has set a water channel in a very narrow pond bank (Thailand)
FIGURE 78
Measuring
transparency can be
very simple, even when the design of the Secchi disk is unconventional
FIGURE 79
A simple gravel filter on a farm supply system helps to
exclude predators
FIGURE 80
Netting can be used to protect freshwater prawns from
predators that arrive overland
FIGURE 81
A large BC Macrobrachium rosenbergii broodstock male from the CAUNESP (Aquaculture Center, São Paulo State University, Brazil) being measured in the ‘scientific’ way (from behind the eye orbit to the tip of the telson)
FIGURE 82
There is a relationship between the total length and the weight of your prawns; this shows a typical length/weight relationship for Macrobrachium rosenbergii
FIGURE 83
You can cull-harvest your ponds by seining the pond towards one end
FIGURE 84
In a longer pond you may find it easier to carry out seining operations with two nets
FIGURE 85
Larger ponds may also be cull-harvested by making several seining operations; beating the water surface with a stick can help to keep the prawns from escaping from the open end of a seine before it is brought to the side of the bank
FIGURE 86
Sorting prawns while seine harvesting
FIGURE 86
Sorting prawns while seine harvesting
FIGURE 87
Market sized freshwater prawns can be kept alive while harvesting continues (Martinique)
FIGURE 88
Prawns destined to be sold alive need clean and well-oxygenated water to keep them in peak condition (Martinique)
FIGURE 89
Cull-harvesting or sampling is an opportunity to check the health of your prawns
FIGURE 90
An internal harvesting sump can be used for Macrobrachium rosenbergii during drain-harvesting
FIGURE 91
Harvesting Macrobrachium rosenbergii from ponds with an internal harvesting sump (Brazil)
FIGURE 92
Cull-harvesting freshwater prawns several times before drain harvesting increases the yield of market-sized animals in your crop (Martinique)
FIGURE 93
The last few prawns may have to be caught by hand, especially when the pond does not drain well (India)
FIGURE 94
Bird predation causes problems during drain harvesting (Hawaii)
FIGURE 95
If you are not marketing your freshwater prawns alive, you should kill-chill them in a bath of iced water immediately after harvesting to get the best quality (Puerto Rico)
FIGURE 96
Freshwater prawns need sorting while being processed (Brazil)
FIGURE 97
Package your prawns attractively (Mauritius)
FIGURE 98
Freshly harvested (blue) Macrobrachium rosenbergii can be cooked (pink) at the pond-side to provide a tasty barbeque (Brazil)
FIGURE 99
Advertise your freshwater prawns at the farm gate (Martinique)
FIGURE 100
Supermarkets sell Macrobrachium rosenbergii in Europe (France)