TECHNICAL REPORT OF THE WORKING PARTY ON SMALL-SCALE SHRIMP/PRAWN HATCHERY
1. INTRODUCTION
1.1 Background
Production of shrimps and prawns through aquaculture in many countries of the Indo-Pacific region has long been in existence and has continued to develop gradually. The governments in the region are very much interested and development programmes on these resources are given high priority. However, segments of developed technologies required are scattered among the various countries and are not uniformly spread in the region.
One of the important components of this industry is that of controlled seed production through hatcheries. This is a vital element that requires concerted attention of the countries in order for this industry to succeed.
FAO/UNDP through its various national and regional technical assistance projects in the region has been trying to assist in this work. It will be recalled that the South China Sea Fisheries Development and Coordinating Programme sponsored the ASEAN Workshop-Seminar on Shrimp Culture in Iloilo City, Philippines, 15–23 November 1976; the First ASEAN Meeting of Experts on Aquaculture, Semarang, Indonesia, 31 January to 6 February 1977; and the Joint SCSP/SEAFDEC Workshop on Aquaculture Engineering, Tigbauan, Iloilo, Philippines, 27 November to 3 December 1977. All the above meetings included discussions and produced reference papers pertinent to the present subject. But this subject compose only a small part of these 1976 and 1977 meetings. Some progress have been attained since then; new developments and recent problems and constraints have also cropped up.
This Working Party was organized to assess the status of this very important segment of the fisheries industry; identify the problems, constraints and gaps that need solution; and whenever possible, come up with recommendations for a realistic and rational future programmes in this field.
It is however realized that the time for this assessment is limited and information available meagre and scattered. To counteract this limitation, the Working Party invited the active workers in this subject from the region. The participants, individually and collectively contributed toward the accomplishment of the task of this Working Party.
1.2 Scale
The usage of the terminology “small-scale” has often been subject to question. This is mainly because of the difficulty of identifying where this begins and where it ends, i.e., its limits or boundaries.
There may be a number of approaches by which we may define “small-scale” from “big-scale” or even “small-scale” with “medium-scale” and “big-scale”. This can be under the following criteria:
In all the above criteria, the limits are vague and can slide from one boundary to the other. It could also vary from one country to another or even in different regions in the same country.
Suppose we arbitrarily designate, just to make a start, small project with the following characteristics:
Admittedly the above quantifications are very arbitrary and can change with time. It may even be inadvisable to make specifications, but alternatively just describe the concept or characteristics of what a small-scale venture is.
1.3 Why “small-scale”
What is important to bear in mind in this type of project, is the socially-oriented objective of the various scales and in particular for the small-scale project. It is the aim in a small-scale projects to provide an opportunity for the fishermen or farmers with limited means, and working individually to possibly make a living, generate additional employment for his family and help in the food production and economy of his country.
2. ENVIRONMENTAL CONSIDERATIONS AND SITE SELECTION
Various environmental considerations should be taken into account before selecting the site for setting up small-scale shrimp/prawn hatcheries. It is realized that the success of shrimp/prawn hatcheries depends on quantity and quality of water supply, food, and management. The following categories are the suggested environmental considerations for site selection.
2.1 Quality and sources of water
Shrimp/prawn hatcheries require continuous supply of both freshwater and seawater. The sources of freshwater are very important to be considered. There are two major sources of freshwater, i.e. well water and surface water. Well water sometime contain very high mineral contents, especially iron and manganese, which are not suitable for shrimp/prawn hatcheries. Surface water is sometime contaminated by some toxic chemicals, therefore monitoring of these chemicals is required regularly. With regards to the source of seawater supply, the supply should be taken from areas where there are no incidences of water pollution.
2.2 Quality of water supply
The ranges of water qualities suitable for shrimp/ prawn hatcheries are suggested as follows:
| Freshwater: | Temperature | : 24–31°C |
| pH | : 7–8.5 | |
| Dissolved oxygen (D.O.) | : > 5 mg/l | |
| Hardness | : > 20 mg/l as CaCO3 | |
| Turbidity | : < 50 FTU | |
| Fe | : < 1.0 mg/l | |
| Mn | : < 0.2 mg/l | |
| Hg | : < 0.001 ppb | |
| Pesticides | : undetectable by GLC (0.001 ppb) | |
| Heavy metals | : < 0.01 ppm | |
| Biological | : < 1.0 mg/l (5 days) | |
| oxygen demand (B.O.D.) Unionized ammonia | : < 0.1 mg/l | |
| NO-2 — N | : < 0.02 mg/l | |
| Seawater | Salinity | 28 - 33 ppt |
| (for dilution process, up | ||
| to 120 ppt is usable) | ||
| D.O. | : > 5 mg/l | |
| Turbidity | : < 50 FTU | |
| Pesticides | : undetectable by GLC (0.01 ppb) | |
| B.O.D. | : < 1.0 mg/l (5 days) | |
| Heavy metals | : < 0.01 ppm (for Hg: 0.01 ppb) | |
| Unionizedammonia | : < 0.1 mg/l | |
| NO-2 — N | : < 0.02 mg/l | |
Regarding the biological properties of water, the water must be able to support the existing aquatic life in the area, and the water must be free from certain organisms producing toxic substances, e.g. red tide.
2.3 Climatic considerations
Pronounced changes of climatic conditions might give adverse effects to shrimp/prawn hatcheries. Suitable site for setting up the hatcheries should be in areas where temperature/humidity do not excessively fluctuate, not too pronounced dry or hot season as well as wet season, and preferably not within the typhoon belt. The land elevation should be high enough so that flooding would not be a problem.
2.4 Facilities
The site should be accessible by either road or water-ways. This is in order to facilitate the transportation of hatchery equipments and supplies, and for seed transportation as well. Electricity is also necessary for the hatchery operation. Besides, the facility of telecommunications would be desirable for the bigger small-scale hatcheries to facilitate the orders from distant shrimp/prawn farms.
3. DESIGN AND CONSTRUCTION
Design of the hatchery should be simple, economic, neat, compact and easy to operate with maximum efficiency.
3.1 Materials used
The material used should be locally available, cheap, and long lasting. It can be made from a wide range of materials: wood, concrete, reinforced concrete, ferroconcrete, fibre glass, and wood with plastic lining.
3.2 Design and variation
There is no fixed pattern for layout of the hatchery. The arrangement of tanks and working space should be based on working performance of the hatchery, and techniques to be used in order to save time and labour when they are on operation. The hatchery should be covered to protect against rain and sun, Figures 1 and 2 are typical layouts of penaeid shrimp and freshwater prawn hatcheries, respectively.
3.2.1 Penaeid shrimp hatchery
Size of hatchery
There is no limitation in size of hatchery, but it should have space for broodstock or maturation tanks, spawning tanks, larval rearing tanks, nursery tanks and algal or food organism rearing tanks.
Broodstock/maturation tank
The shape of the tank depends on the preference of the individual farmer. However for successful operation the tank should have a capacity of at least 10 tons with a water depth minimum of 1.20 m (Fig. 3)
Spawning tank
Shrimp should be spawned in a separate tank. The minimum water capacity required is 200 liters.
Larval rearing tank
For maintenance and management point of view, the tank should have water depth up to but not over 0.80 m. The minimum capacity of the tank should be about 2.0 tons. Fig. 4 is a typical larval rearing tank.
Nursery tank
Main function of the tank is to keep the postlarval after PL 1–5. The tank should have water depth of 0.60 m with a bottom area of about 12 m2
3.2.2 Freshwater prawn hatcheries
Size of hatchery
The hatchery can vary in size. The smallest one should have a space for broodstock tank, spawning tank, larval rearing tank and phytoplankton-culture tank.
Broodstock tank
The broodstock of freshwater prawn can be easily obtained with a steady supply either from farms or natural broodstock. The tank is mainly designed to keep the broodstock before and/or after they spawn. The minimum requirement of the water depth of brood-stock tank is 0.50 m with various shapes.
Spawning tank
The egg of the freshwater prawn are already fertilized. The berried females can be hatched in aquarium, jar, bucket and/or pail. There is no limitation of the depth of water, and the size.
Larval rearing tank
The freshwater prawn can be reared from larval stage to juvenile stage in the tank with water depth of 0.20 m. For successful operation the larval rearing tank should be designed to have a water depth at least 0.50 m.
Phytoplankton tank
This tank is not necessary for the hatchery that is designed for operation with the clear water system. But for those who prefer to use the green water system, or combined green water — clear water technique, the phytoplankton tank is required. To utilize the sunlight with maximum efficiency, and management, the tank should have a water depth of not more than 0.50 m. The shape of the tank can be either circular, square or oval.
3.3 Methods of construction
The tanks can be constructed at the site or precast concrete can be used or ready-made product that are available on the local market, can be purchased.
3.4 Auxiliary facilities
3.4.1 Seawater
The seawater has to have a salinity range of 28 to 32 ppt. The water intake may either be from an inshore well or right in the sea. For the later case, extreme care must be taken to be sure that the water will be free from fish, jellyfish as well as silt and mud during heavy runoff. This is done by employing a sand filter. The pipes are made of PVC and should be fully exposed for easier maintenance.
For ground water, it should not contain high levels of minerals, e.g. sulphur, iron, magnesium, manganese, lead, etc. It is essential that the seawater is consistently of the same good quality or with stable chemical parameters.
The hatchery will need a water pump (stainless steel type) with a capacity of 50 m3/min of sea water. Two submersible pumps with a capacity of 2 hp are needed.
3.4.2 Freshwater
The freshwater has to be pure, of drinking quality and not too hard. The pH should be 7 to 7.5. A pump with a capacity of 25 m3/min of freshwater is needed.
3.4.3 Air supply system
A source of air for aeration system can be either a low pressure and high volume given by a Roots air blower or cylindrical air pump, or a high pressure and low volume given by a compressor. However, the former is preferred, because of its safer, less complicated, and provides oil-free air. For the small-scale hatchery, the ordinary cylindrical air blowers may suffice, since the oil introduced into the system has no significant impact on the larval survival, and its cost is only a fraction of what a Roots blower costs. The life span is also much longer.
The size of the aeration system depends on the extent of the hatchery operation. For a 1-m deep tank, a 3.6 liter min m2 of air is enough to ensure aeration of the high organic load in the rearing tank.
Carborundum grinding stones 9 cm long, 3 cm in diameter, hollow inside with an inside-well thickness of 0.5 cm are suitable. The airstone is used with 9 mm (inside diameter) plastic tube and a heavy sinker tied at the neck of the airstone. This type of airstone may be used at a rate of one airstone per 5 m2 of area. PVC pipe are preferred for air distribution lines.
Stoppage of aeration is fatal to the larvae, and sudden power failure can be disastrous. Therefore a battery powered warning system must be installed to notify the culturist of any stoppage of the aeration system. For the compressor type, warning system that is pressure oriented to the air tank is required. For the blower type, a relay-type of warning system is needed.
3.4.4 Electricity
It is essential to have electricity continuously because the air blower is driven by electric motor. Water pumps and housing also need electricity. Two generators (400 V, 50 HZ, 1500 rpm) with an output of 10–15 KVA are required.
4. MANAGEMENT AND OPERATIONS
The management and operations of shrimp/prawn hatcheries in the region basically follow similar lines. However, they differ in detail, often depending on local conditions.
4.1 Broodstock development and spawning
For prawn, berried females are readily available from the wild or under captive conditions.
For shrimp, gravid females are used to be derived mostly from the wild but increasing numbers are being produced under controlled conditions, by unilateral eyestalk ablation of females, with a minimum body weight of 80 gm. The broodstock is kept in 60 m3 concrete rectangular tanks (8 × 5 × 1.5 m), 12 m3 circular, ferro-cement tanks (4 m in diameter, 1.2 m in depth) and pens (16 × 16 × 4 m), made from bamboo and nylon netting. For the tanks, the water exchange is of the flow through system, or recirculating static water with frequent change is also used. The feeds used include pellets, cockle, squid, mussels (Perna sp) and cow liver. The optimum salinity for broodstock tanks is believed to be 28–31 ppt.
Gravid females have been produced from tanks with and without a sandy substrate.
The frequency of broodstock examination in the tanks varies from daily (18–20 hrs) and once every two days, but the duration after the initial eyestalk ablation can be as long as 3–7 days.
Gravid females are transferred to individual spawning tanks with aerated, full salinity water. Eggs may or may not be chemically treated; nauplii are transferred to the larval rearing tanks, with a stocking density of 50–100 nauplii/liter.
4.2 Larviculture water management and monitoring
For prawn, green water, clear water as well as a combined green water/clear water rearing system is used.
For clear water, the rearing water is usually changed partically (20–60 percent) each day, except in the recirculation system, where only the water lost by siphoning is replaced by freshwater. Water change is carried out after the daily siphoning of bottom wastes.
The rearing tanks are covered to reduce temperature fluctuation and to provide shade for the larvae.
For shrimp, salinity is maintained at 27–33 ppt and water temperature at 26–30°C.
Starting with Zoea 1, 10–20 percent of water is changed daily.
Starting with Mysis 1, 30 percent of seawater is changed daily.
Daily monitoring includes observation of larvae for mortalities, disease and feeding behaviour and excess of food on the tank bottom which is siphoned together with other sediments.
4.3 Warning systems
Some hatcheries are equipped with warning sirens in the event of power breakdown. Most hatchery operators keep a close and continuous watch of their hatchery systems.
4.4 Feeds and feeding
4.4.1 For shrimp, diatoms (Skeletonema or Chaetoceros) which are cultured in the hatchery, are fed from Zoea 1 to Zoea 3 at 10 000–50 000 cells/ml. Tetraselmis can be fed starting Zoea 1 or Zoea 2 up to Mysis 3 at 10 000–20 000 cells/ml.
4.4.2 Brachionus, which are cultured on Chlorella or Tetraselmis, can be given at mysis stage at the density 5 to 10 ind/ml. If Brachionus is not available, Artemia nauplii can be given to the mysis.
4.4.3 Artemia nauplii are given at PL-1 with the density of about 50 Artemia nauplii/PL.
4.4.4 A recent development is the feeding of boiled egg yolk (20–150 μ; ave 50 μ) at 15–25 particles/ml from Mysis 2 to Mysis 3 with a reduced density of algal feds.
4.4.5 Pellets (30 percent protein) of 100 μ size are fed at 0.5 gram/ton 4 times a day starting at PL-1.
4.4.6 For prawn larvae, feed used include Artemia nauplii, egg custard, or egg custard mixed with fish flour, shrimp meal, mussel or clam meal, screened fresh fish or cockle, but for the first 5 days, usually only Artemia nauplii are used. Feeding is carried out 3–6 times, with Artemia given as the last feed in the evening. The feed is spread throughout the tank, usually with the aeration stopped temporarily to facilitate observation of the feeding. Sometimes, an extra feeding is given during the night.
4.5 Diseases and their control
Preventing disease through proper nutrition and maintenance of good water quality is more important than control. However, occurrence of Lagenidium and other fungal diseases is controlled by application of 0.01 ppm malachite green or treflan, bacterial disease by 1 ppm chloramphenicol and 3 ppm oxytetracycline, and Zoothamnium by 10 percent formalin at 5 ppm.
For disease prevention, all rearing tanks and utensils are properly cleaned, and in some cases totally sterilized by chlorination.
4.6 Predators and other enemies and pests
These are not major problems but occasionally some aquatic insects are found in prawn larval tanks.
These pests can usually be removed by dipping them out.
4.7 Harvest methods
Harvest is done by partial draining, then scooping out the postlarvae. In bigger tanks, water is siphoned down to 1/3 total volume and the postlarvae are gradually drained into a bagnet.
4.8 Transport methods
In short-distances, the fry are placed in a tank with aerated seawater but for long-distances, the fry are packed in plastic bags in oxygenated seawater of 20–24°C. Stocking density depends on size and age of fry and transport time.
5. ECONOMICS OF SMALL-SCALE HATCHERY
Economics of size of small-scale hatchery was generally of considerable variation within the region, and it is affecting a clear definition of this concept. Economic studies must be conducted concurrently with biological research to make such determinations and demonstrate them in pilot or extension activities. The technology of farm shrimp/prawn is just becoming established on a commercial scale; a relatively high level of risk is therefore anticipated. Factors controlling markets and production costs are complex and variable to some extent. There is minimum information on the economic aspects available from the region.
5.1 Economics of size
Economics of size of small-scale hatchery varies in the region regarding to:
5.1.1 Land purchase/lease
5.1.2 Equipment price
5.1.3 Construction and material cost
5.1.4 Labour cost
5.1.5 Loan interest
5.1.6 Availability of electric power from the community line.
Based on existing local developments, Indonesia suggests clarified small-scale hatchery on the basis of capital investment up to US $50 000, Malaysia US $100 000. Philippines US $25 000 and Thailand up to US $200 000.
5.2 Optimizing production through inputs and its economics
To optimize production through inputs and its economics, consideration on the:
5.2.1 Design of hatchery should be simplified and made of locally available material.
5.2.2 The method of larval rearing should be simplified.
5.2.3 Avoid unnecessary or non-functional structures to reduce unnecessary expenditures.
5.2.4 Perfect layout to ease movements and provide efficiency on the operation is required.
5.2.5 Decentralized aeration system which is economical and practical should be practised.
5.2.6 A hatchery managed and operated by members of a family could be the economical and optimum size.
It is recognized that there is a need to measure bases on standard economic procedure the benefit/cost ratio of various levels of these operations. The format with the capability to develop budget for production system is needed. The investment return on equity, break even price, etc. are the sensitive factors.
5.3 Marketing and price/cost of production/profits
5.3.1 Marketing cost analysis are considered as an integral part of effort to develop shrimp/prawn hatcheries throughout the region.
5.3.2 At present, generally marketing of shrimp/ prawn has no particular problems.
5.3.3 In future years some competition for export markets may arise, therefore product quality must be at a high standard.
5.3.4 Profit is most sensitive to yield and size of shrimp/prawn which is dependent upon biological factors that influence the potential of a commercial operation.
5.3.5 In small-scale operation, cost of production can be extremely variable and difficult to state in monetary terms.
5.3.6 Production and other data must be measured over a relatively long period of time in order to be valid.
6. PROBLEMS AND CONSTRAINTS
The Working Party made a critical review of various issues and agrees to the opinion that establishment of a small-scale hatchery for shrimps and prawns that is technically and economically viable is not an easy task. The participants view that before suggesting one or the other technology for hatchery construction and its management its detailed economics and its appropriateness in respect of the country's socio-political aspirations and policies must be critically assessed.
Some of the more important problems which are likely to stand on the way to materializing the concept of small-scale hatchery operation would relate to:
The members made the following recommendations:
The technique of growing postlarvae and juveniles into marketable size on more economic basis should be further improved and extended to the farmers on priority basis; the government, through appropriate planning and policy divisions; will have to facilitate further expansion of the shrimp culture industry. This will then generate accelerated need for the supply of quality shrimp seed and encourage new entrepreneurs to go for hatchery establishment.
Collection of spawners from wild sources or development of broodstock in the ponds and their induced spawning under controlled conditions involve not only a great deal of technical skill and experience but also a number of equipment requiring initial capital. The potential small-scale operators (generally the fishermen or the rural people of limited means) have neither the required knowledge nor adequate capital. Therefore, government support in respect of maintenance and supply of spawners at the individual farmer level, at least during initial stage, will be essential.
Constant production and supply of adequate quantity of live food is a pre-requisite to commercial hatchery operation. The process of live food culture is as complicated as shrimp culture itself. Government supportive and promotional role in this field also is vitally important initially.
A small-scale hatchery has to be big enough to generate sufficient income to the operator; in many cases, the hatchery may be the only source of income to the family of the operator. To maintain the hatchery at good efficiency and productive level, even the small hatchery would need certain expensive equipment like a water pump, an air blower, a generator (in case there is no electricity supply) etc. Though essential, it is not possible for the small-scale operators to purchase one or all of these equipment, individually. Government may have to take a role in organizing a number of operators into viable groups so that each group may share the cost and enjoy the benefit of the expensive equipment.
The hatchery operators must have an assured market for their produce. Any surplus production must be purchased by the government at fair price in order to help keep up the production incentive of the farmers.
In most instances, the sites which are environmentally suitable for establishing a hatchery are remotely located and devoid of essential infrastructure facilities, e.g., roads, electricity, medical and schooling facilities, etc. The government should identify areas of high potentials and provide the needed infrastructure facilities. Security aspect of such areas should also be taken cared of by the government.
To promote hatchery as a new industry further government support in terms of subsidy or special privileges e.g., exemption of import duty and sales taxes on capital equipment, will be very helpful.
Quite often, there are conflicts amongst the various government agencies on the land utilization. The coastal land may belong to the forestry, revenue, agriculture, industries or other departments. Government policy decision at appropriate level to utilize one or the other plot of such lands for fisheries purpose is required. In view of great economic potential and possible social benefits, the use for fishery should demand special consideration from the government.
7. RECOMMENDATION FOR FUTURE PROGRAMMES
7.1 Research needs
Research was discussed by the Working Party and it was found to be an important consideration for overall development of shrimp/prawn hatcheries.
The first step the group considered important was to establish the research needs and objectives that would generally apply for the entire region. These needs were established as necessary short or long term studies. It was generally agreed that there is a considerable need to conduct research and this research is presently being subsidized for the benefit of small-scale producers before the technology can be transferred. The following list of research needs was agreed upon by the group. This list was not prioritized and it can be applied to the entire region of consideration, each country having specific requirements.
Broodstock development of shrimp/prawn
Reproductive biology and physiology
Larval rearing
Nutrition and feeding
Post harvest handling
7.2 Training and extension
The Working Party clearly indicated the need for extension and training. The various levels and groups to be trained were discussed and they varied depending upon the country of concern.
The types of training, whether they be pilot demonstration or Government workers, should be given consideration in order to develop country programmes. There were many factors to be considered, i.e. the language, the level of participation, the proper background of the persons dealing with the farmers, the methods used, all were very important to the discussion.
The following list was agreed upon as accomplishing the development of future programmes concerned with training.
7.3 Development needs
Among the more important recommendations arising from the Working Party are the items concerned with future development. The major sources of assistance for shrimp/prawn hatchery development in the region are expected to remain the same. These efforts must be coordinated with national requirements which have been developed by the individual governments within the region.
In some cases countries are taking action for the formulation of suitable projects. In other cases this information should be made available to the various donor agencies as representative of the general needs within the region or country.
The following list was developed after much discussion as covering the basic development needs as envisioned by the Working Party.
The above discussions and recommendations for future programmes of research, training and extension, and development covered a wide range of initiatives to provide full-scale support to assist greatly in the economic improvement of small-scale producers.
Assistance could take many forms based on the needs of a particular country within the region.
It was agreed that initial preplanning and evaluation would be necessary for each of the above points of research, training/extension and development on a country by country basis within the region.
Fig. 1. Layout of the small-scale shrimp hatchery
Fig. 2. Layout of the small-scale prawn hatchery
Fig. 3. Broodstock holding tank
Fig. 4. Larval rearing tank
