D. Tech. Science by V. Muthuwan, 1998
Summary :
A prototype of a closed recirculating system for intensive culture of marine shrimp (Penaeus monodon) was developed and its performance was evaluated. A series of the experiments was conducted on ammonia production of shrimp, characteristics of shrimp pond water and treatability, nitrification rate of submerged biological filter, and removal efficiency of biotreatment animal (Artemia). The result obtained from these experiments were used to determine capacity of settling tank, maximum ammonia loading, flow rate, estimated biological media volume, and stocking density of Artemia for a recirculating, intensive, shrimp culture system.
Maximum excretion rate of ammonia-N by shrimp occurred between 3 and 6 hours after feeding. There was an inverse relationship between excretion rates (g/BW) and size of shrimp. Three mathematical models were developed for prediction of ammonia-N excretion rates of tiger shrimp based on weight, size, and food fed, for example, the daily ammonia-N excretion of a 25-g tiger shrimp was 12.7 mg. Similarly, the daily ammonia excretion of Artemia increased with the size of the animal. The maximum ammonia-N excreted from Artemia (7.7-mm) was 2.6+/-0.2 microg ammonia-N/ind/d. Ammonia released from shrimp feed and feces was relatively low at about 1.3 and 4.0 mg/g/d based on dry weight of shrimp feed and feces in 24 hours, respectively.
Excretion of feces was also related ot the feeding rate of shrimp. Average amount of feces generated from feed intake for various sizes of tiger shrimp was 19.7 +/- 4.8% (+/- SD) on dry weight basis. The models represented relationships between body weight and feed intake, and feces excreted. Solid wastes generated from Artemia included feces and exuviae of the animal. It was found that daily comulative solids produced from individual Artemia increased with size of the animal. The maximum solid production of 8-mm Artemia was 0.09 +/- 0.01 mg dry wt./ind/d.
Feeding efficiency of Artemia on different types of phytoplankton was determined in attempt to use Artemia for removal of excessive phytoplankton in the culture system. Feeding rates of Artemia increased with increasing size of the animal. Increasing phytoplankton concentration from 10 to 100 mg dry wt/L enhanced feeding rates of Artemia at all stages and with all types of phytoplankton, except for Chlorella sp. whose highly density seem to interfere with feeding of small Artemia. Artemia preferred Tetraselmis sp. over Chlorella sp. and Chaetoceros sp.
During the 129-day experimental period, shrimp grew from 0.12 +/- 0.00g (2.6 +/- 0.3 cm) at stocking to 19.5 +/- 1.2 g (13.0 +/- 0.3 cm) at harvest, with an average daily weight gain 0.15 +/- 0.02 g/d. The average total shrimp harvest was 10.7 +/- 1.1 kg/tank (19.6 m2), or 0.55 kg/m^2/crop or 1.56 kg/m^2/yr. The average survival of shrimp was 55.1 +/- 0.7%. The average maximum feeding rate at the end of experiment was 2.0 +/- 0.3% body weight d-1 (11.0 +/- 0.8 g m-2d-1), and mean feed conversion ratio was 1.78 +/- 0.13 for the culture period.
(AARM Newsletter, Vol. 3, No. 4, October 1998)