The stocks are usually harvested upon reaching the marketable size (about 30 pcs/kg). Harvesting may be done completely at one time or partially depending on demand. Complete harvesting is usually undertaken by the use of a bag net installed at the drainage gate of the pond. The shrimps that go with the drained water are collected at the bag net and the remaining ones are hand picked when the pond is completely drained. The shrimps should be harvested only when they are not molting because newly molted shrimp have soft shell and fetch lower price.
Partial harvesting is normally practiced in culture operation with higher stocking density (i.e. in semi-intensive or intensive culture). The stock, upon reaching the marketable size (30 g and above) can be harvested by the use of selective harvesting net (Fig. 23).
The selective harvesting net is a modified shrimp trap net installed in the pond with mesh size big enough to retain the bigger shrimps. Several harvesting nets may be installed at various pond locations. This harvesting device is more efficient at night. Selective harvesting improves pond yields because it reduces intra-specific competition thus giving chance to the smaller ones to grow better.
The shrimps can be partially harvested after 2–1/2 months of culture or when a lot of stocks reach the marketable size. This operation is usually carried out at bi-monthly interval until most of the stocks are harvested or the remaining ones reached the marketable size.
Upon harvesting, the shrimps should be washed and placed immediately in chilled water (10–15°C) for about 15 minutes. They are then packed in styrofoam box with alternate layers of crushed ice at a ratio of 1:1. Smaller styrofoam boxes are preferred to facilitate transportation. If bigger styrofoam boxes are used, it is better to fill up the box with chilled water, shrimps and ice to avoid physical damage on the shrimps at the bottom.
Fig. 23. Selective harvesting net
