Effects of artificial substrates on the growth, survival and spatial distribution of Litopenaeus vannamei in the intensive culture condition

 In order to investigate the effects of artificial substrates (vertical surface of polypropylene fabrics) on cultured shrimp, we reared 28-day old Litopenaeus vannamei post-larvae (PL28) intensively for 90 days at a density of 510 shrimp/m2 in each of 8 tanks. Two tanks containing no artificial substrate were a control group, and 1, 3 and 5 artificial substrates were present in other 6 tanks. The volume of each tank was 100 L. In the tanks with artificial substrates, the percentage of shrimp distribution on the bottom was less significant (P<0.05) than that in the control tanks. The percentage of shrimps attached to the artificial substrates increased and fewer shrimp occupied the tank bottom as more artificial substrates were added to the tanks. Moreover the trends were more significant as rearing days increased. These results showed that artificial substrates could disperse the shrimp from the tank bottom onto the artificial substrates and thus alleviate the negative effect of high stocking density on shrimp growth in the tanks. Both the average weight and survival in the tanks with artificial substrates were significantly higher (P<0.05) than those in the control tanks. Furthermore, weight and survival increased when more artificial substrates were added. Because the shrimps in all tanks were supplied with suitable water quality and adequate nutritional food, we suggest that the differences of growth and survival were affected mainly by living space added with the addition of artificial substrates.