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7 Aquaculture to Restocking
order to prevent microbial infection and self-decomposition, which will reduce
water quality. Brief changes in temperature, salinity and mechanical stimuli, which
can cause premature hatching, are avoided. In order to minimize temperature fluctuations, a water flow-through method is applied at a rate of 1 L min
–1
. Fresh seawater
is pumped through an activated carbon filter and stored in a 200-m
3
concrete tank
before gravity-feeding to the hatchery (Fig. 7.7). The current generated by the water
feed also assists in removing waste products by producing an upwelling outflow
through drainage pipes at the centre of the tank. This system is able to maintain an
average temperature of 28°C, a salinity of 30–33 practical salinity unit (psu) and a
Fig. 7.6  Two types of plastic baskets used for nursing the egg capsules, 5 mm mesh (  left) and
10 mm mesh (  right). (Photograph J Nabhitabhata)
Fig. 7.5  Egg clusters of the bigfin squid, Sepioteuthis lessoniana acclimatized in a plastic basket.
(Photograph J Nabhitabhata)