Effects of stocking density and aged sediment on tiger prawn, Penaeus monodon, nursery system

Abstract

Our study aimed to assess the effects of stocking density and aged sediment on a tiger prawn, Penaeus monodon, nursery system. Twenty-four aquaria were assigned to 12 treatments in a 3 × 4 factorial arrangement, namely, three stocking densities of prawn fry PL35: 72, 108, and 144/m 2; by sediment with four ooze contents: 0, 33, 66, and 100%, four degrees of sediment deterioration. Two replications were used for each treatment. The fry were reared for 54 days. Stocking density was the main factor affecting the growth of prawn fry; ooze content had a relatively slight effect. The growth rate was best at 72/m 2. The growth rate at 108/m 2 was not significantly different from that at 144/m 2. Survival rates were affected by stocking densities only. Survival rate at 144/m 2 was the lowest. There was no significant difference in survival rates between 72/m 2 and 108/ m 2. Since the sediment on day 54 did not show any marked deterioration, it appeared that the nursery period could be extended beyond 54 days. Since organic loading and toxic metabolites were proportional to stocking density, which directly affected water quality and growth of fry, stocking density should be one of the main factors to consider in nursery culture. Since the reduction-oxidation potential was closely related to most constituents in the sediment and the growth and survival rates of fry, it can be used as an indicator of the sediment aging process and as a semi-quantitative indicator of the sediment's effects on cultured organisms.