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Harvesting
Basically there are two methods of harvesting: cull-harvesting drain harvesting.
Harvesting time depends partly on growth rate and the size of animals you want to
sell. This, in turn, depends on your market requirements. It also depends on the
pond management technique chosen. Cull-harvesting is used to harvest market-sized
animals from the pond at intervals and removes the faster growing prawns. In tropical
ponds cull-harvesting usually starts 5-7 months after PL have been stocked, or sooner
if juveniles have been stocked. After cull-harvesting commences, you should totally
seine each pond once per month or partially seine it twice per month (i.e. seine
half the pond twice per month or all of it once per month). Take out the market-sized
animals and sell them. Keep the smaller ones and soft-shelled animals in the pond
for further growth. After about 8-11 months, drain the pond and sell the whole harvest.
Cull Harvesting : In this technique a seine net is pulled
through the pond to remove market-sized animals. The net may be a simple seine or
one constructed especially for the purpose, usually made of monofilament nylon,
and provided with floaters, sinkers and sometimes a bag. The size of the seine you
use depends on the size of pond you are using it for. Nets which are 2.5 m high
with a length equivalent to 1.6 times the pond width are suggested. The mesh you
choose depends on the size of animal to be marketed. Although stretched knot mesh
sizes of as low as 0.7 inches (1.8 cm) are sometimes used where there is a market
for small prawns, the usual recommended mesh size is 1.5-2 inches (3.8-5 cm).
Care must be taken to ensure that the bottom of your seine is kept on the bottom
of your pond. If you do not, many prawns will escape beneath it. Preferably you
should pull the seine down the long axis of the pond (this is why rectangular ponds
of 30 m maximum width are preferred) so that the ends of the net are pulled along
the banks of the pond. Seining different halves of the pond once every two weeks
avoids disturbing the whole of the pond at once.
Harvesting prawns through seining
Drain Harvesting:
The method and efficiency of drain harvesting depends on the design of the pond.
As with any other method of harvesting, speed is important and harvesting should
start very early in the morning while the temperature is cool. You can partially
draw down the pond water level during the night before harvesting commences.
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Harvesting by castnetting
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Prawns from cull harvest
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Prawns from final harvest
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