Shellfish Breeding and Hatchery Management (2+1)

9.1.2 Shrimp broodstock quality

9.1.2 broodstock quality

The basic requirement for healthy and quality seed production is healthy broodstock of desired size so that it will yield maximum number of viable eggs. There are two sources for the broodstock. One being the wild natural waters, the other from the culture ponds.

For shrimp hatcheries, mostly broodstock is obtained form wild habitat. Captive broodstock for P.monodon is still under experimentation, while for P. indicus α P. japanicus, captive broodstock development has become possible. However, the brooders from wild are found to be superior to captive brooders which are usually smaller in size. Males of a minimum size of 200 mm total length weighing over 90-150g (9-12 months) are reported to give good results in tiger shrimp seed production. Other criteria of brooder or mother shrimp quality are,

1. Big size without any damages

2. Pigmentation

3. Clear eyes and open telson (broad)

4. Complete antenna

5. Full stomach - no white patches

6. Ovary  occupying the full abdomen portion

7. Thelycum loaded with sperm mass

8. If non-impregnated, there must be readiness for mating

9. If males, bigger size and active.

Transportation of brood stock

Usually the adults are collected from deep sea and from the collection site to the hatchery site, the breeders are transported in bag containing 40-50 litres of sea water @ 4 - 6 nos per bag. After introduction of the breeders, the bag is filled with oxygen and sealed. In this condition the brooders can be transported without much stress. In order to avoid any casuality, the temperature of the bag may be reduced with ice cubes packed polythene bags kept surrounding.

Spawner transportation, particularly by air, by adopting chilled saw dust method is not advisable to any of the currently cultured species in India. P. monodon can not tolerate a temperature below 12⁰C and P. semisulcalus can not withstand exposure for long.  

Acclimatization of brood stock

After the brooders are brought to the hatchery, they are to be acclimated to the hatchery conditions by transferring the brooders to tubs with seawater used in hatchery. Care must be taken to do this slowly in case there is considerable difference in salinity, pH and temperature.

After acclimation, brooders are treated with 100 ppm formalin for about ½ hr for disinfection. In case brooders exhibit some sign of disease such as lying on one side/ abnormal pigmentation/ lesions in the exosleleton, a dip treatment of antibiotic (50 ppm oxytetracycline/ erythromycin/ perfuran) for 10 minutes can be given. Such disinfected and healthy brooders are then transferred to maturation tanks.