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24<br />

was followed below by rearing tank, <strong>for</strong> nauplii and zoea larvae, then<br />

another <strong>on</strong>e <strong>for</strong> mysis to PL1_5 stages and finally a large <strong>on</strong>e <strong>for</strong> post<br />

larvae.<br />

The more favoured nursery approach necessitates rearing the<br />

nauplii through different stages by supplying appropriate feed —- live<br />

or inert. The success <strong>of</strong> any hatchery operati<strong>on</strong> depends mainly <strong>on</strong> the<br />

availability <strong>of</strong> the phyto plankt<strong>on</strong>-— the meadows <strong>of</strong> the sea, because<br />

the large scale producti<strong>on</strong> <strong>of</strong> molluscan, crustacean and fish larvae<br />

mainly depend <strong>on</strong> mass culture <strong>of</strong> particular species <strong>of</strong> unicellular<br />

algae as a food source in the early stages <strong>of</strong> development (Loosan<strong>of</strong>f<br />

and Davis, 1963).<br />

In the western hemisphere and in China multimilli<strong>on</strong> dollar<br />

hatcheries with high-tech facilities produce large number <strong>of</strong> seed stock<br />

in c<strong>on</strong>trolled envir<strong>on</strong>ment through out the year.<br />

In south east Asia particularly in.Thailand, Taiwan, Ind<strong>on</strong>esia<br />

and Philippines, small hatcheries also known as backyard hatcheries<br />

using low densities and imtreated water is <strong>of</strong> comm<strong>on</strong> occurrence. They<br />

are <strong>of</strong>ten affected by bacterial and viral diseases and water quality.<br />

Hatcheries have been marginally successful, as fast growing<br />

giant tiger <strong>prawn</strong> E. m<strong>on</strong>od<strong>on</strong> reaching a maximum <strong>of</strong> 336 mm does not<br />

mature in captivity. Only the Chinese white shrimp E. chinensis is<br />

well suited <strong>for</strong> captive maturati<strong>on</strong>.<br />

It takes about 6 weeks <strong>for</strong> the larvae from spawning to stocking<br />

in grow out p<strong>on</strong>ds to complete the hatchery cycle. However, hatcheries<br />

remain as the weakest link in the producti<strong>on</strong> cycle.<br />

In India, success was attained to spawn and rear most <strong>of</strong> the<br />

cultivable species <strong>of</strong> shrimps in the laboratory using the Japanese<br />

technology‘ with appropriate local alterati<strong>on</strong>s (Silas, 1978).

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