Shrimp Hatchery

1. Shrimp Hatchery
INTRODUCTION
Shrimp is a valuable aquatic food resource high in protein and commands good export markets.
It has become the main target commodity for aqua farming in recent years. Traditionally,
shrimp fry are trapped and held in ponds and later collected by shrimp gatherers for stocking in
grow-out ponds. With increasing demand for shrimp, supply of wild fry for the increasing
number of shrimp farms has become insufficient and inconsistent. The breakthrough in the
completion of the life cycle of commercially important shrimps in captivity, such as the tiger
shrimp (Penaeus monodon), the Japanese kuruma ebi (P. japonicus), the eastern shrimp (P.
orientalis) and the banana shrimp (P. indicus or P. merguiensis), has greatly enhanced mass
production of shrimp fry under hatchery conditions. The excellent growth performance of these
hatchery-bred fry in grow-out ponds strongly shows that the shrimp hatchery can answer the
industry needs for ample supply of shrimp fry for farming.
Importance of this Study:
At the end of this assignment we will know how to:
 To construct an ideal shrimp hatchery.
 To maximize production with minimum investment.
 Various types of shrimp hatchery found in world.
 Layout and design variation of a shrimp hatchery.
 Essential components and infrastructure of a shrimp hatchery.
SHRIMP HATCHERY
A shrimp hatchery is one of the locations where shrimp are kept during their lifecycle
development on the way to becoming fully-formed shrimp for commercial sale. Shrimp
hatcheries can be found in any region where the shrimp industry is active, and some regions
have numerous hatcheries supplying large farming operations. People can also make their own
shrimp hatchery out of common materials, to grow their own shrimp at home.
SUCCESS OF SHRIMP HATCHERY
From many years of accumulated experience and research findings, the success of a shrimp
hatchery depends on:
 The choice of a suitable site
 Effectiveness and efficiency of the hatchery design
 Experience of hatchery technicians
 Efficiency of operational management

2. SELECTING SUITABLE SITES FOR A HATCHERY
Prior to the establishment of any shrimp hatchery, it is of primary importance to carry out a
thorough feasibility study to determine the suitability of the proposed site. The main criteria
followed are water quality, availability of spawners and site accessibility.
For establishing large-scale modern hatcheries, the criteria for hatchery site selection must be
rigidly followed because it is costly to change site when high financial inputs have already been
committed. However, site selection for smaller hatcheries are less rigid than the bigger ones.
Criteria in the selection of a suitablesite for a hatchery
1. Sea water supply
The sea water used in a hatchery should be clean, clear and relatively free from silt. The water
quality should be stable with minimal fluctuation in salinity. Suitable sites are usually found in
sandy and rocky shore ecosystem where there is clean, clear and good quality sea water all year
round. Sites not suitable for hatchery are swamps and muddy shores where the water becomes
turbid during heavy rains or due to turbulence. Avoid river mouths where abrupt lowering of
salinity often occurs during heavy rainfall. An added advantage of rocky and sandy shores is
that good quality sea water is relatively near the shoreline thus reducing the cost of piping
installation and pumping cost. The hatchery site should also be free from possible impact from
any inland water discharges containing agricultural or industrial waste.
2. Availabilityof spawners
Presence of spawners at the vicinity of the proposed site is of considerable advantage in
ensuring consistent supply of spawners, reducing the cost of transportation which could affect
the rate of spawning.
3. Availabilityof power source
Electricity is essential to provide the necessary power to run equipment and other life support
systems in the hatchery. Although some marine pumps and aerators can be driven directly by
handy generators, the shrimp hatchery can therefore be operated in areas without electricity
supply. However, it is more economical to operate it in areas where there is a reliable source of
electricity. Installation of an on-site standby generator is absolutely necessary especially in
areas where there are frequent lengthy power failures and fluctuations.
4. Freshwater supply
Freshwater is essential for daily hatchery operation such as salinity adjustment, equipment
maintenance and for domestic use.

3. 5. Accessibility
Ideally, a hatchery should be sited in areas where there are active shrimp farming operations so
that the shrimp larvae produced can be easily transported and distributed to the grow-out
ponds. Hence, the site chosen for hatchery establishment must be easily accessible to facilitate
communication and transportation.
6. Climate conditions
A hatchery can be established in any climatical condition. However, all the commercial
hatcheries take full advantage of nature in terms of energy source and supply of good quality
water. Sunlight is the basic requirement for hatchery operations especially in the mass
production of natural food used as feeds for the growing shrimp larvae. In the temperate region
where adequate sunlight is only available in certain periods of the year, hatchery operations are
usually confined to a certain suitable season. In such situations, hatchery production is
relatively limited to a short period of time. The optimal temperature for hatchery design may
be necessary in areas where there are pronounced long period of rainfalls which often reduces
the intensity of light, cause turbidity in water supply and lowering of water temperature.
HATCHERYDESIGN AND CONSTRUCTION
Basically, there are two hatchery systems being adopted. The large-tank hatchery which was
developed in Japan is still the popular system applied in many Asian countries such as Taiwan,
Thailand, Philippines and Indonesia. The small tank hatchery which originated from Galveston
USA, has been applied in the Philippines and to same extent in Malaysia and Thailand. Recently
a modification of the above systems has been developed which combined the beneficial
characteristics of both systems taking into consideration the limitation of spawner supply.
There are three determinants in designing a hatchery viz: target species, production target and
level of financial inputs. Although multi-purpose hatchery design for shrimps and finfish may
not necessarily be the same. In any case, the target species must be clearly identified before
designing the hatchery.
Production target can be determined based on a market demand and financial input. In the
case of species such as P. monodon at which the production of fry depends on the availability of
spawners from the wild, production target is limited by the supply of spawners. This limits the
production capacity of the hatchery. Whereas in P. japonicus and white shrimps at which
spawners are easily available, production capacity is unlimited. Tank capacity up to 2500 cubic
meters can be seen in many large-scale hatcheries in Japan where P. japonicus is the primary
species grown. However, in most Southeast Asian countries where tiger shrimp forms the
target species for hatchery production, tank capacity is considerably reduced due to limited
spawner supply from the wild.
Hatchery design is aimed at achieving the production target which determines the size of the
hatchery. The tank capacity is based on an approximate ratio between algal culture tank and

4. larval rearing and nursery tanks. Desirable algal tank capacity is 10–20% of the larval rearing
tank capacity. The capacity of maturation tank depends on the number of spawners needed.
Size of hatchery
Generally, the size of a hatchery should be based on its functional requirements and economic
efficiency. Based on the level of operation, production output and financial investment,
hatchery practice can be broadly grouped into three categories viz: small-scale, medium-scale
and large-scale hatchery. The major characteristics of each group are shown in Table 1.
1. Small-scale hatchery
This is a “backyard” hatchery usually owned and managed by the shrimp grower himself using
family members or immediate relatives for additional labour. The main goal is to supply his own
shrimp farm with the required number of fry and the excess may be sold to neighboring
growers. Usually the hatchery site is an extension of the farm house with floor space ranging
from a few square meters up to about 1000 square meters. In such hatchery operation, the
total production capability seldom exceed 5 million postlarvae per annum and the hatchery is
operated by not more than 2 technical personnel. In Southeast Asian countries, such hatchery
entails a capital investment of not more than US$30,000 and operational cost of less than
US$10,000.
Table 1. CRITERIA FOR CLASSIFICATION OF SHRIMP HATCHERIES
Item Small Medium Large
1.
Ownership and
operation set-up
Family members
serve as hatchery
workers
Small
cooperative
Big corporations,
national agencies
Fry for self-use
Supply fry to
members
Fry for commercial
purposes
2.
Area or extent
covered
Usually using the
backyard area
2000–5000
sq.m.
5000 sq.m to 1 ha.
3.
Amount of
production
1–5 million/year
10–20
million/year
More than 20
million
4.
Number of
employees or
technicians
1 technician,
2 workers
3 technicians,
3–4 workers
3–6 technicians
6–10 workers
5. Total tank capacity 20–100 tons 100–1000 tons
More than 1000
tons

5. 2. Medium-scalehatchery
This type of hatchery is relatively larger than the small-scale hatchery in terms of capital
investment, hatchery size, production capability and scale of operation. While hatchery
management is somewhat similar to that of small-scale hatchery, the production capability
range between 10–20 million post-larvae per annual and is operated by about 3 technical
personnel and 3–4 labourers. This type of hatchery is usually put up by small cooperatives to
supply the required shrimp fry to its member growers. Private enterpreneurs or government
agencies may also establish hatchery of such operational scale to produce fry of sale or
distribution to the growers. Capital investment in Southeast Asian countries for such hatchery
ranges between US$30,000 to US$100,000 and operational investment of not more than
US$50,000.
3. Large-scale hatchery
This scale of hatchery is commercially run by big corporations, national agencies or cooperative
projects. While the capital and operational investment far exceed that of the medium-scale
hatchery, production capability of such hatchery usually exceeds 20 million post-larvae per
annum. Such hatchery is centrally and systematically managed and is supported by a pool of
not less than 6 technical personnel and 6-10 labourers. Capital investment and operational cost
are over US$100,000 and US$50,000 respectively.
Hatchery facilities
In designing a hatchery, ample space should be provided for the rearing and support facilities
needed in the operation. A functional hatchery should have the following essential
components-
1. Maturationtanks
The major constraint in hatchery operation of tiger shrimp is the limited supply of spawners
from the wild. Hence, eyestalk ablation techniques can be used to augment the scarcity of
spawner supply. Thus, maintaining ablated shrimp in maturation tanks would ensure a constant
supply of gravid females.
The shape of maturation tanks can either be circular, rectangular or oval. The tank capacity may
vary from 5 to 40 tons with depth ranging from 1.2 to 2 meters. If the shrimps are kept for less
than 5 weeks, bottom substrate is not needed in the tank. The tank is installed with an inlet
pipe from the wall and a double cylinder standpipe at the center for drainage. This system
facilitate continuous flow-through of sea water.

6. 2. Spawningtanks
Spawning tanks should be circular with a flat or conical-shaped bottom. Water holding capacity
may vary from 50 liters to 1.5 tons. The tank can be made of fiberglass, Plexiglass, plastic or
marine plywood. The tanks are used to temporarily hold the gravid females until spawning.
3. Larval rearing tanks
Two types of rearing tanks are being used to rear the newly hatched larvae. In Japan and
Taiwan, larger tanks with a capacity of more than 50 tons are being used. In Southeast Asia,
most of the hatcheries use smaller larval rearing tanks of about 3 tons capacity.
3. i) Small Tank System
The larval rearing tank may be circular, rectangular or oval in shape with tank capacity ranging
from 0.8 to 3 tons. The bottom of circular tanks may either be flat or conical. Rectangular or
oval-shaped tanks always have flat bottom. The circular tank is usually 1.8 m in diameter and
1.2 m in depth with a central double cylinder standpipe drainage system which can be used for
continuous flow of sea water when the larvae reach mysis or post larval stage. Rectangular tank
is about 1.5 × 5 × 1 m in size. The drainage pipe is set at the side of the tank. The drain pipe is
also used for harvesting. In all types of tanks, sea water is delivered into the tank through an
inlet pipe installed at the top of the tank.
3. ii) Big Tank System
The tanks used are rectangular or square in shape with
capacity varying from 50 to 2000 tons or more (5 × 5 ×
2m or 20 × 50 × 2m). The tanks can either be located
outdoors or if located indoors, transparent roofing
should be provided to allow for sources of sunlight .In
a big tank system, spawning, hatching and larval
rearing operations are done in the same tank. The
larvae are reared for 35–40 days (PL25-PL30).
4. Live food culture tanks
In mass cultivation of live food organisms, size of tanks
used usually ranges from 1 to 20 tons. The tanks can
be made of either fiberglass, polyethylene, marine
plywood or concrete. On the average, the total tank
capacity for live food culture is about 20% of the total
tank capacity for larval rearing.
Fig 01: Water storage and
filtration tank

7. 5. Water storage and filtration tank
The water storage tank is normally elevated to effectively distribute water by gravity to the
hatchery. The water storage tank capacity should be at least 20% of the larval rearing tanks.
Storage tanks are normally constructed out of reinforced concrete to withstand the water
pressure.
When the water is turbid, installation of a filtering screen and sand filter unit becomes
necessary. The filter chamber may be constructed adjoining the holding tank. There are two
types of filter systems: (a) gravity filter where water is pumped into the filter chamber over the
surface of the filter bed and allowed to pass through the filter material by gravity to the holding
chamber which is located under the filter chamber and (b) reversing filter, where water is
pumped directly to the space under the filter chamber and pumped upward through the filter
to the surface and on to the holding tank. In both systems, the filter chamber usually contains
either white sand, charcoal, gravel, or all the
three as filter material. The advantage of the
reverse system is that water pass slowly
through
The filter material and the whole surface area
of the filter is utilized. It is easy to backwash by
spraying water from the surface of the filter and
the detritus underneath are easily washed out.
On the other hand, gravity filter method allows
water to pass through the water chamber too
fast and do not fully utilize the surface area of
the filter unless it is provided with a pipe spray water
over the whole surface area. The disadvantage of the
gravity filter systemis that the filter is easily blocked.
With detritus after a few days of operation resulting in turbid water and difficulty in back-
washing.
Aeration
Aeration is essential during the entire larval rearing process in maintaining sufficient dissolved
oxygen concentration in the water, ensuring even water temperature throughout the water
column through turbulence and also help reduce the ammonia content in the water.
Aeration may be provided with a roots blower, rotary blower or an air compressor. A blower
provides large volume of low pressure air while an air compressor provides small volume of
high pressure air. An air blower runs continuously while a compressor which is equipped runs
with the pressure tank whenever
Fig. 02: A gravity water flower

8. The pressure is low. The compressor automatically switches on when pressure drops below a
pre-determined level. In a hatchery, low pressure air available at large volume is more desirable
than high pressure air at small volume. Moreover, the hatchery tanks are seldom more than
two meters deep. Rotary air blowers are not designed for oil free operation and have a
tendency to blow oil particles into the air line producing oil slicks on the surface of the water.
Air filters at the inlet and outlet pipes are therefore needed. When the capacity of an air blower
is less than 10 HP, ordinary air filters for automobile may be used at the inlet pipe, however, for
blowers with high horsepower ratings, synthetic foam can be used. Adjustable pressure tank
with resin glass beads or Bagasse as filter materials are used for the outlet pipes. The roots
blower is more appropriate for hatchery purposes because it seldom breaks down, less
complicated to use and does not produce oil slicks.
In culture tanks with depth less than 2 meters, an air pressure of about 0.2–0.3 kg/cubic
centimeters and a volume of 4–5 liters/m2/minute is sufficient to oxidize the dissolved organic
matter in the tanks.
Since continuous aeration is essential to the survival of larvae in high density, any prolonged
power interruption would seriously affect the culture organisms in the tank. Thus, it is essential
to install an automatic switch which starts a standby generator whenever there is a power
failure. A battery operated warning device to signal the crisis and the required operation of the
standby generator can also be used.
Marine pumps
Centrifugal and submersible pumps are commonly used in hatchery operation. Centrifugal
pump is more desirable in the big hatchery because it has a higher total head capacity (Total
head is the difference in elevation between the surface of the source of water and the point of
discharge).
The selection of the size and type of marine pump depends on the size of hatchery and the daily
water requirement. For the small or backyard hatchery, a submersible pump with a discharge
pipe diameter between 1" to 4" and a discharge capacity of 6–20 tons/ltr is sufficient to provide
the water needed. Medium and large hatcheries normally use centrifugal pumps. The size of
the pump depends on the total water
requirement per day and the maximum
pumping time. The power required can be
calculated with the following formula:
Fig. 03: A Roots Blower

9. Where Pm = output prime mover (kw)
r= specific gravity of water to be handled (gm./am) is normally 1.0
Lay-out and construction
Once the project site is selected and production target defined as an aerial survey of the
proposed site will help to determine the perimeter of the area. An aerial view would show the
important topographic characteristics such as rivers, shoreline, mountain and low lying plains. A
master plan of the hatchery is then made. Lay-out of the hatchery should provide a schematic
design of the location and integration of various facilities such as buildings, broodstock tanks,
larval rearing tanks, nursery tanks, spawning tanks, pump house, air supply and power house,
laboratory, staff house, piping for water supply and drainage canal. The lay-out plan should
include the exact dimension, locality, shape and size of said facility. Examples of a simple lay-
out of small, medium and large scale hatcheries are shown in figure-
Fig. 04: Layout of medium scale hatchery.

10. Fig. 05: Layout of small scale hatchery
Technical drawing should show the detail structure of the facility and size and quantity of
support materials needed to ensure stability of the facility. From the technical drawing, the
owner can roughly estimate the cost of construction. Since the technical drawing presents
details of the structures such as thickness of the tank wall, amount and size of iron bars and
mixing proportion of concrete, the price of these materials will be easy to canvass to arrive at
the cost estimates. However, estimations of construction costs should be done item by item,
before making the total estimation. In the total estimates, labour cost should be included.
PREPARATION OF BROODSTOCK FOR SPAWNING
Inadequate supply of spawners remains as one of the major constraints in the development of
the shrimp farming industry especially for species such as the tiger shrimp, Penaeus monodon.
Recent success in eyestalk ablation techniques has greatly enhanced constant supply of
spawners through ablating captive broodstock to maturation. At the present time, the supply of
broodstocks and spawners still depend on captures from the wild.
1. Conditioningof broodstock
Upon arrival in the hatchery-
 The broodstock are first acclimatized in holding tanks for 4–7 days.
 The holding tanks should be big enough to provide proper space and aeration. 60% of
the water in the tanks is changed daily.

11.  Once the animals have recovered from transport stress, they are induced to molt by
manipulating salinity of water in the holding tank.
 The salinity is decreased by about 4–5 ppt for two days and then increased to the
normal salinity of the seawater. Majority of shrimps will molt after changing salinity.
Mating occurs during this time when the females are newly molted. The shrimps are
then ablated 2–3 days after molting or when the shell is completely hardened.
2. Induced maturation
Only suitable broodstocks are used for eyestalk ablation. The criteria are:
 Complete appendages
 Presence of spermatophore in the thelycum of females
 Size should at least be 100 gm.
Presently, the most practical way of inducing maturation is by unilateral ablation of either right
or left eyestalk of the female. Ablation is done by using a razor blade to cut/open the eye, then
squeezing out the eyestalk from the base to the tip with the thumb and forefinger or using the
fingers alone to break and squeeze the eye. The ablated animals are stocked in maturation
tanks at a density of 5–6 per square meter and a sex ratio of one male to one female.
Maintenanceof broodstock in maturationtanks
The broodstocks are fed with squid, mussel or cockle meat or pellet feeds at the rate of 10% of
total biomass. The water in the tank is allowed to flow through continuously or changed daily at
60–70% of total capacity.
Sampling
Gonadal development of an ablated female is checked 3–5 days after ablation while checking
for gravid females is carried out every other day. Sampling and checking are done at night or at
any time if the tanks are sufficiently covered and kept dark. During sampling, an underwater
flashlight, tied to a pole is held close to the shrimp so that the light strikes perpendicularly on
the dorsal part of the body where the ovaries are located. Water in the maturation tank can be
lowered to 30 cm to allow the worker to get inside for closer observation. Only gravid females
with stages III or IV ovaries are collected and transferred to spawning tanks.
Larval Feed
Under natural conditions, penaeid shrimps are either omnivorous scavengers or detritus
feeders. In general, shrimp larvae feed on phytoplankton, detritus, polychaete and small
crustaceans and their food preference changes with age. They start feeding at protozoea stage.
Protozoea and early mysis stages prefer phytoplankton .At mysis and early postlarvae, food
preference changes to zooplankton such as rotifer or brine shrimp. As the larvae grow older
than P6, feeding habit changes again to that of a bottom feeder. Polychaetes, chopped mussels
or cockle meat are fed during these stages.

12. Large-scale production of phytoplankton for larval rearing can be obtained in two ways: by
direct fertilization of seawater in the rearing tanks or from pure culture. Many hatcheries
depend largely on brine shrimps to feed their growing shrimp and fish larvae. Brine shrimp
(Artemia) eggs are sold commercially but the quality varies with the trade brand representing
different strains, geographical origin and processing methods. The rotifer, Brachionus plicatilis,
is the most important zooplankton utilized as live food for various cultivable marine animals.
Dry acetes diet and egg custard are also used as larval feed.
In addition, many other types of feed have been developed and tested as part of penaeid
shrimp larval rearing strategies. These feed may either be frozen or dry material from molluscs,
crustacean tissue, soy bean cake, soy bean curd, egg mustard and fertilized eggs or oyster.
Other types are available as formulated diet or the newly-developed microparticulate and
microencapsulated diets. However, the choice of a particular feed used should be properly
evaluated based on the following criteria-
 Availability and ease of handling (including technical support);
 Feed performance; and
 Feed cost and rate of return on capital.
The basic feeding strategies regarding the type of larval feed in penaeid shrimp hatchery
employed to date are summarized as follows:
 Use of mixed diatoms through direct fertilization in combination with dry or fresh feed
material such as soybean curd, soy bean cake, fertilized oyster eggs followed by live
food organisms such as rotifer, artemia nauplii.
 Use of mixed diatoms through direct fertilization and/or pure culture diatom followed
by rotifer and Artemia nauplii.
 Use of mixed diatoms through fertilization and/or pure culture of diatoms in
conjunction with fresh/frozen mollusc and crustacean tissue.
 Use of mixed diatom through direct fertilization and/or pure culture of diatoms in
conjunction with other dry feed materials or formulated diet.
 Exclusive use of microencapsulated or microparticulate larval feed.
 Exclusive use of wet or dry product of crustacean tissue.
PREPARATION OF FACILITIES FOR SPAWNING, HATCHING AND
LARVAL REARING
Preparation of basic facilities such as spawning tanks, hatching tanks, larval rearing tanks, water
supply and aeration systems is one of the most important activities in any hatchery operation.
Hatchery production declines if maintenance and preparation of these facilities are not well
done.

13. Tank facilities
Spawning, hatching, larval rearing and nursery tanks are basic requirements in any hatchery
and preparation of such tanks prior to operation are accomplished in two ways:
1. Newly constructed hatchery
Tank facilities especially concrete ones in a newly constructed hatchery must be conditioned
first before any hatchery operation is done. Alum (Potassium aluminum sulphate), a cheap
chemical, can be used to neutralize tanks. The newly constructed tanks are first filled up with
sea or freshwater, small pieces of alum are then broadcasted into the tanks at a rate of 250
g/cubic meter and allowed to stand for about one week. Fiberglass or wooden tanks can be
conditioned by filling up with water until the pH of the water in the tanks are stabilized.
2. Operationalhatchery
Occasionally, larvae in operational tanks get infected by diseases. To deter such occurences,
tanks must be properly cleaned with freshwater, dried and exposed to the sun for at least one
day prior to stocking. After every run or every other run of operation, the tanks should also be
disinfected with 12% sodium hypochloride solution at the rate of 200 ppm for 24 hours. When
the tanks are ready, filtered fresh/seawater is introduced and aeration is checked especially in
the spawning and hatching tanks. Strong aeration is necessary to float shrimp eggs owing to its
demersal nature. If aeration is not strong-enough, eggs will sink and mix with the scum at the
bottom resulting in low hatching rate.
Water qualityand supply
Water, being one of the most important factors in hatchery operation, must be regularly
monitored for important physico-chemical parameters, viz: salinity, pH, N-NO2 temperature.
Often times, turbid water flowing out from the sand filter is bacteria laden. This occurs when
detritus, small organisms and dirts pass through the filters under high pressure. To avoid this,
initial water passing through the filter must be drained off for about 20–30 minutes or until
water becomes clear. Disinfection of the sand filter with 12% sodium hypochloride solution at
least once a month will help in keeping the filter clean.
SELECTION OF SPAWNERS AND EGG COLLECTION
Although spawning occurs throughout the year among tropical species of shrimps, there are
distinct periods of the year when majority of the shrimps spawn. In the case of P. monodon in
Southeast Asian waters, there are two pronounced spawning season, from December to March
and June to September with only one pronounced period, viz: June-September in the case of P.
merguiensis and P. indicus.
While spawners of these species of shrimps are supposedly available all year round, they are
abundantly caught during the spawning season.

14. A gravid female can be easily recognized by the presence of a very large and distinct diamond-
shaped dark green mass of ovary between the first and second abdominal segment below the
dorsal shell. Selection of spawners can be easily done by holding the animal with its ventral
body facing a light source The criteria used for selecting spawners from the wild are:
 Stage IV ovary
 Complete appendages
 The back is not broken
 Presence of spermatophore underneath the thylecum; and
 The color of the shrimp especially P. monodon should be pink with a faint greenish tint.
Spawners which are slightly reddish could be due to stress caused by abrupt lowering
of the water temperature during transportation by fishermen who try to delay
spawning. Stressed spawners give very low spawning rates.
Procurement and transportationof spawners
Spawners are usually collected by professional fishermen. In Japan, hatchery operators can
easily procure spawners from fish markets because fishermen bring them back alive as live
shrimps are preferred by consumers over dead ones. In other Southeast Asian countries,
however, hatchery operators must deal directly with fishermen, provide them with the
necessary facilities (e.g. containers, battery operated air pumps, etc.) and teach them handling
techniques to ensure getting quality live spawners. In order to do this, hatchery operators must
have comprehensive knowledge of the operating gears and the means of transporting
spawners. In cases where spawners are available only during a certain spawning period (e.g. 3–
4 months in P. orientalis) hatchery operators should carefully plan the hatchery operation to
meet their requirements.
There are several ways by which spawners are transported from the field to the hatcheries.
They can be transported in-
 Live fish holding compartment in the boat with running water system (very convenient
for hatcheries close to the fishing ground).
 Holding tank with aerated seawater at controlled temperature (22–24°C) using ice in
plastic bags and transported by trucks.
 Plastic bags injected with oxygen and packed in styrofoam boxes. The water
temperature can be controlled by using ice mixed with sawdust. In this case, the
rostrums of shrimps could be covered with plastic caps to prevent puncturing of plastic
bags, and
 Bamboo or PVC tubes: the spaweners are immobilized in separate tube without
overstraining them. While transporting in boats, the shrimps are held in cool (22–24°C)
aerated water in tanks but are transferred to plastic bags with oxygenated water while
transporting on land. Tube transport along with reduced temperature reduces the
frequency of untimely spawning in transit and/or injuring themselves.

15. Treatment of spaweners
Upon arrival, each spawner is nowmally placed directly in a spawning tank without any further
treatments. However, during winter or when there is known spread of disease, spawners are
usually treated with either (a) Treflan (trade name), 0.5–1 ppm (b) KMnO4, 3ppm or (c)
Formalin, 25 ppm for 10–15 minutes.
Spawning activity
In nature, adult shrimps mate after the females have molted. Spawning usually occurs while
swimming with the spermatophore in the thylecum and eggs are released from the genital pore
which is located at the base of the third pereiopod; sperms are likewise discharged into the
water through an apperture at the base of the fourth pereiopod. Fertilization is external.
Spawning usually occurs between 0200 to 0300 hours at water temperature and salinity ranging
from 25 to 30°C and 28 to 32 ppt, respectively.
Egg collectionand treatment
After spawning, the animal is removed from the tank the following morning. The eggs are then
cleaned either by siphoning into egg collectors or draining 2/3 of the water through a filter net
that effectively retains the eggs within the tank . When draining is completed, the scum is then
removed using a scoop net with a mesh size bigger that the shrimp eggs. (Fig. Collection of egg)
The tank is then filled up with new seawater During the cold season, fungus and bacteria are
likely to infect the eggs during incubration. Preventive treatment normally consists of dipping
the eggs in 1 ppm of methylm ene blue or 0.5 ppm of malachite green for 10 minutes or 3 ppm
KMnO4 for 30 minutes. After that, the eggs are transferred to a cleaner tank for further
incubation and subsequent hatching. From the incubation/hatching tank, samples of eggs are
counted to determine the number of eggs spawned per female.
Hatching and Transportationof nauplii
Eggs of most species of shrimps within 12–18 hours after fertilization at temperature and
salinity range of 26–30°C and 30–23 ppt, respectively.
1. Determinationof hatchingrate
The density of nauplii is estimated a day after hatching.
Nauplii from three 100 ml water samples taken from the
spawning tank are counted and averaged. The total number
of nauplii in the tank is then obtained by multiplying the
volume by the average density.
To determine the hatching rate, the following formula is
employed:

16. Nauplii are then directly transferred to larval rearing tanks.
2. Transportationof nauplii
At the nauplii stage, the larvae hardly feeds and thus depends on its yolk for development. This
stage is easy to transport even for long durations. In some cases, where the site of the
established hatchery is far from the spawner collecting areas, it is more advantageous to
transport the nauplii instead of the spawners which are more prone to stress.
The nauplii are transported to the hatchery in two ways:
Plastic containers - Only strong and healthy larvae should be transported. This is done by
concentrating the nauplii at the water surface with a light source at night, gather them by
scooping with a plastic or glass container. The larvae are then transferred into plastic jars which
are half-filled with seawater. The container is then gradually filled up. A 20 liter plastic
container can contain a maximum number of 500,000 nauplii. The open end of the container
must be properly sealed to prevent leakage. The survival rate after 6–8 hours during
transportation is more than 50%.
Plastic bags - Each bag containing about 6–8 liters of water can be stocked with 200,000
nauplii. The water in the bags are oxygenated and the open end is closed with rubber bands.
The survival rate is about 80–90% if transport takes about 4–6 hours .
Larval rearing
From the spawning tank, smaple of eggs are counted to determine the number of eggs
spawned per female. In normal condition, fertilized eggs hatched within 12–15 hours. The
hatching rate is measured by assessing the number of hatched nauplii. Nauplii are then
transferred directly into the 40-ton tanks if the number of nauplii is between 0.5 million and 1
million. They are then reared directly in the large tank up to the 25th post larval day. On the
other hand, if the number of nauplii is less than 0.5 million, they are stocked in 2.5-ton indoor
tanks at a density of 100–150 larvae/liter. The larvae are reared either to the third mysis stage
(M3) or one day old (P1) post larvae. They are then transferred to the outdoor 40-ton nursery
tanks for further nursing.

17. 1. Larval rearing in small indoortanks
After hatching, the newly hatched nauplii are stocked at a density of 100–150 nauplii per liter in
the 2.5-ton larval rearing tanks with fresh filtered seawater filling up to 3/4 of tank capacity. No
feed is required at the nauplii stage since the nauplius still utilizes its yolk as food. However,
diatom are inoculated immediately after stocking to ensure availability of feed when the nauplii
molt into the protozoea stage.
I) Protozoea stage
This is a critical stage of larval rearing. The larvae at this stage start feeding on external food
and feed on minute and easily digested microscopic algae such as Skeletonema costatum,
Chaetoceros sp. and Tetraselmis sp. The optimal feeding of phytopla ton in the rank is 50,000
cells/ml for Skeletonema or Chaetoceros and 10,000 cells/ml for Tetraselmis.
On the other hand, there is a bright prospect in the use of wet or dry processed invertebrates
tissue or encapsulated or microencapsulate feeds in shrimp hatchery feeding strategy. The
feeding scheme advocated is based either on the exclusive use of a marine invertebrate wet or
dry processed tissue as feed for all the shrimp larval stages or the exclusive use of
microencapsulated The use of these types of feed can reduce production cost as well as make
the feeding regime of shrimp larvae more convenient especially for small-scale hatcheries. The
use of marine invertebrates as food organisms can be purchased at low prices and in large
quantities since these are available locally. The commonly used food organisms are paste
shrimp (Acetes sp.), rock shrimp (Metapenaeus sp.), stomatopod (Oratosquilla sp.) blood cockle
(Anadara sp.) and mussel (Perna sp.)The shrimp larvae are fed with either wet or dried
processed crustacean tissue during protozoea stage.
Fig. 6: Schematic diagram of prawn production from hatchery to grow-out ponds.

18. II) Mysis stage
The larvae at this stage will start feeding on rotifers (Brachionus plicatilis) or the brine shrimp
nauplii required depends on the density of shrimp larvae being reared. Each mysis larvae
consumes about 100–200 rotifers or about 20–50 Artemia nauplii per day or a standard ratio of
about 5 grams dry Artemia cysts is required per cubic meter of rearing water.
2. Larval rearing in large nursing tanks
The initial water level in the 40-ton nursery tanks during stocking is 100 cm. The nauplii density
is usually about 20–50 per liter. Immediately after stocking, diatom starters are inoculated to
ensure bloom of the desirable species. Technical grade fertilizers can be used directly to
enhance algae growth. The fertilizers used are:
KNO3 3 ppm
Na2HPO4 0.3 ppm
It is pertinent to monitor the types and density of algae in big tanks to ensure that the optimal
density is maintained.
During the protozoea stage, about 10–20 cm of fresh filtered seawater is then added daily.
However, the amount of water added is dependent on the diatom growth. When diatom
density is below the desired level in the culture tank, more cultured diatom and fertilizers are
added to accelerate algal bloom. On the other hand, over-blooming of algae should also be
controlled by shading or by draining out a portion of water and replenished with fresh
seawater.
ROUTINE HATCHERYMANAGEMENT
The maintenance of optimal environmental conditions is necessary for maxima growth and
survival of the cultured organisms.
1. Maintenanceof water quality
 Salinity - Biologically, most penaeid shrimps do not breed in brackish water while
mating, spawning and even hatching of eggs take place only in the open sea. Salinity in
spawning grounds normally ranges from 30 to 36 ppt. Thus, seawater salinity in
spawning tanks should be maintained at 30–32 ppt to ensure good hatching rates.
Moreover, low salinity affects larval growth during the first 15 days of rearing. Though
abrupt or extreme variations in salinity may adversely affect larval survival, slight
variations in salinity is not detrimental.
 Temperature - Temperature directly affects the metabolic system of any given species.
In penaeid shrimps, eggs do not hatch at temperatures lower than 24°C. Larvae usually
grow and molt faster at higher temperature. The optimum temperature is 26–31°C.

19. Below this level, larvae do not grow well and molting may be delayed. The protozoea of
P. monodon, for instance, molt to mysis stage within 4 days at temperatures ranging
from 28°C to 31°C, however, molting takes 6 days when temperature drops to 24–26°C.
Slight increase in water temperature above threshold may be lethal in the tropic
species. Gradual variations in temperature throughout the day is not critical, however,
sudden changes even as narrow as 2°C can cause high mortalities due to stress and
temperature stock.
 Dissolved oxygen - Dissolved oxygen is a critical factor in larval rearing. High mortalities
can occur if aeration stops even for only one hour.
 pH and nitrogenous compound - Normal pH of seawater ranges from 7.5 to 8.5. The pH
value is a key indicator of changes in the water environment of the rearing tank relative
to ionized and un-ionized ammonia. This is so because NH3 and NH4 ratio in water is pH
dependent. If pH value is high, this signifies increased levels of un-ionized ammonia
(NH3) which is toxic to larvae. Ionized ammonia (NH4
+) however, is not toxic because it
is unable to pass through the gill membrane of the larvae. Safe ammonia concentrations
in water should not exceed 1.5 ppm for NH4
+ and 0.1 ppm for NH3.
2. Feeds and feeding schemes
Shrimp larvae at the first protozoan stage cannot efficiently seek food as the swimming
appendages have yet to develop. On the other hand, diatoms often overbloom in the rearing
tank especially those in the outdoor hatchery. This causes high mortality due to attachment of
diatom on the appendages of the larvae which makes them unable to move and molt properly.
In addition, overblooming of diatom collapses easily the next day and this results in water
fouling. To monitor if the feed is sufficient in the rearing tank, the density of diatoms is counted
daily before and after water management. Once diatoms in the larval rearing tank become
brown, new diatom cultures are added to meet the density requirement of the larvae. The
approximate density sufficient for larvae in the rearing tank is 50,000/ml for Chaetoceros sp. or
Skeletonema costatum and 10,000/ml for Tetraselmis sp. Brachionus must be maintained at 20
individuals/ml and Artemia at 50 grams for every 100,000 post-larvae. Overblooming of
diatoms during summer days is controlled by shading the larval rearing tank or by draining out a
portion of the water and replenishing with fresh filtered seawater.
3. Monitoring
Environmental parameters such as water temperature, salinity and pH should be checked twice
daily. Meanwhile, the estimated number of larvae at each stage of development should also be
recorded. Count larvae in three 1-liter samples for small tanks and 10 times for big tanks. The
average number of larvae per liter will give an idea of total amount of larvae. However, larval
estimates can be done until P4 only because the larvae changes to demersal feeding habit after
this stage. The precise number of larvae will be known during harvest when head counts are
done.

20. NURSERY OF POST LARVAE
Since small tank nurseries normally produce up to P5 - P6 post-larvae only, such stages cannot
be stocked directly in grow-out ponds. Therefore, nursing of post-larvae from the small
hatchery is still necessary. Nursing of post-larvae can be done in many ways, eg. in concrete
tank, earthen pond or in net cages.
1. Concrete tanks
Concrete tanks are prepared by filling up with filtered seawater provided with aeration and
pure cultures of diatom added to preserve water in good condition and make it less
transparent. Ideal stocking density of the larvae is about 50/cubic meter of water. It is advisable
to use substrates to increase surface area in the nursery tank, because postlarvae have a habit
of clinging to the wall and tank bottom. Polyethylene nettings can be used and being synthetic,
they do not decompose in water and can last longer without deterioration.
2. Earthen pond
Nursery pond size ranges from 500 to 20002 and water depth at 40–70 cm. The nursery pond
should have at least one gate installed with a fine screen (1 mm mesh size) to prevent
predators and competitors from entering.
Fig. 7: NURSERY POND
P9-P10 are suitable sizes for stocking in the nursery ponds. Stocking density is 100–150
individuals per square meter.
Prior to stocking, the pond should be completely drained and dried until soil cracks. In cases
where the pond cannot be completely drained, derris root (Rotinone) may be applied at 20
kg/ha to eradicate predators. Derris root is crushed until it breaks, soaked on water overnight
and the resulting milky solution applied. Fertilizers are applied at 1000 kg/ha and 50 kg/ha for
organic (chicken manure) and inorganic (Ammonium sulphate) fertilizers, respectively.
Water exchange depends upon the time of spring tide when water can enter the pond.
Chopped mussel or cockle meat are fed to the larvae at the rate of 10% the total biomass. The
culture period lasts 30–45 days when larvae becomes P40 or P60.

21. 3. Nursery cages
Cages made of synthetic netting can either be floating or stationary in calm water in bays,
lagoons or fishponds. Sites for installation of the nursery cages should be as far as possible free
from biofouling because nursery cages are made of very small mesh size nettings which can be
easily covered up by bio-foulers and thus prevents water exchange. The cages are normally
supported by frame and by floating bouys made of bamboo or Styrofoam drums. Stationary
cages are held up by bamboo or wooden poles. Postlarvae (P6–7) is suitable for stocking in cages
at a stocking density of 1000–2000 per cubic meters of water.
HARVEST AND TRANSPORT OF LARVAE
P21-P25 is suitable for harvesting from nursery tanks because this
size can be stocked directly to the pond and easily be transferred.
The larvae in nursery tanks can be harvested by first reducing the
water level to about 1/3 of its depth and then can be collected
from the bag net positioned at the tip of the drained pipe. This
method is efficient enough to collect all the larvae.
The postlarvae can also be harvested with a scoop net, dip net or
seine net after 2/3 of the tank water has been drained. This
method however, is time-consuming.
The number of harvested postlarvae is estimated from a single
water basin of known volume from which animals within have
been individually counted. This basin serves as a constant where
visual comparisons are made with the rest of the harvest in similar basins. This method is
reliable especially if the size of the larvae is uniform.
Methodsof transporting post-larvae
Tanks – Post-larvae can be transported in plastic, fiberglass or canvass tanks of a suitable
transport size (500–1000 liters) and provided with aeration. Temperature of water can be
lowered by floating plastic bags with ice. Post-larvae at a density of 200–500/liter can be
transported for 10 hours without heavy mortalities.
Plastic bag - Very often, post-larvae are transported in polyethyelene bags provided with
oxygen. The bag (60 cm × 40 cm) is first filled with 6–8 liters of fresh seawater and then packed
with 3000–5000 post-larvae. The density may be reduced if the expected transport time is
longer. After properly tightening the mouths of the bags, they are placed in styrofoam boxes or
plastic buckets. Temperature is reduced to about 22–25°C by crushed ice mixed with sawdust
on the bottom, side and top of the styrofoam box. Under these conditions, post-larvae may be
kept alive for more than 12 hours during transport.
Fig. 8: Nursery Cages
(stationary cages & floating
cages)

22. GUIDELINES — SHRIMP HATCHERIES
 Community property rights and regulatory compliance
 Community-community relations
 Community-worker safety and employee relations
 Environment-ecosystem protection
 Environment-effluent management
 Food safety, drug and chemical management
 Environment storage and disposal of hatchery supplies
CONCLUSION
Shrimp hatcheries may require some facilities, such as pipe -lines, to be located on public land.
Where this is the case, hatcheries shall ensure that local communities are consulted, approval is
granted by pertinent authorities and adequate precautions are taken to prevent the facilities
from being a hazard, nuisance or eyesore. In residential areas and especially at night, special
care shall be given to minimize noise pollution, such as that caused by electric blowers,
generators or other intensive activities. Shrimp hatchery management should attempt to
accommodate traditional uses of coastal resources through a cooperative attitude toward
established local interests and environmental stewardship. Hatcheries should not block
traditional access corridors to public mangrove areas and fishing grounds.

23. References:
1. Crespi V., Coche A. (2008) Food and Agriculture Organization of the
United Nations (FAO) Glossary of Aquaculture.
2. FAO (2010) State of World Fisheries and Aquaculture.
3. Frankenberger (2002). A livelihood analysis of shrimp fry collectors in
Bangladesh: future prospects in relation to wild fry collection. Report
from the Shrimp Action Plan. Department of Fisheries/DFID.
4. Huntington (2002). Scoping study for the certification of shrimp
aquaculture in Bangladesh. Report from the Shrimp Action Plan.
Department of Fisheries/DFID.
5. BOBP (1993) Nursery rearing of tiger shrimp post larvae in West Bengal,
India. BOBP/WP/92.
6. BOBP (1994) Cage nursery rearing of shrimp and prawn fry in Bangladesh.
BOBP/WP/92.
7. Banks (2002). Brackish and marine water aquaculture. Report from the
Fisheries Sector Review. DFID.
8. Chanratchakool, P. 1993. Health Management in Shrimp Ponds. Aquatic
Animal Health Research Institute, Bangkok, Thailand. 111 pp.
9. FAO. 2007. Improving Penaeus monodon hatchery practices. Manual
based on experience in India. FAO Fisheries Technical Papers T446. Rome,
FAO. Online version.
10. Kongkeo, H. 1997. Comparison of intensive shrimp farming systems in
Indonesia, Philippines, Taiwan and Thailand. Aquaculture Research,
28:789-796.
11. Kungvankij, P. 1986. Shrimp hatchery design, operation and
management. NACA Training Manual Series No.1. NACA, Bangkok,
Thailand. 88 pp.
12. Limsuwan, C. & Chanratchakool, P. 2004. Shrimp farming industry in
Thailand. National Research Council of Thailand, Bangkok, Thailand. 206
pp.
13. Rosenberry, B. 1996. World Shrimp Farming 1996. Shrimp News
International, San Diego, USA. 164 pp.