Simulated transport of Scylla serrata zoeae at various loading densities

摘要

Percent mortality of mud crab Scylla serrata zoeae was determined after 6 h of simulated transport at mobile and stationary conditions at loading densities of 10, 20, 30 and 40 X 10~3 ind centre dot l~(-1). Mortality was not significantly differentamong treatments immediately after transport. Surviving zoeae were stocked in basins, fed with Brachionus rotundiformis and mortality was compared 15 h after transport. There was no significant interaction between loading density and condition (mobile and stationary) of transport (P > 0.05). However, larval mortality varied significantly among densities (P < 0.001) regardless of the condition. A density of 10 X 10~3 ind centre dot l~(-1) had the lowest mortality (0.56 +- 0.76 percent) followed by 20 X 10~3 (1.28 +- 0.39 percent), 30 X 10~3 (4.3 +- 0.25 percent), and 40 X 10~3 (4.3 +- 0.31 percent) ind centre dot l~(-1). In another experiment, the effect of transport duration was determined at a constant loading density of 10 X 10~3 ind centre dot l~(-1) in control (not subjected to packing and transport), shaken and unshaken conditions. Zoea mortality did not differ significantly (P > 0.05) after the 6, 9, and 12 h transport. Regardless of the duration, mortality was lowest in the control (0.41 +- 0.05 percent) compared to those in the shaken (0.99 +- 0.13 percent) and unshaken (0.79 +- 0.12 percent) conditions. Likewise, the condition but not the duration of transport affected larval survival at 15 h post-transport. Mortality was lower in the shaken(1.92 +- 0.22 percent) than in the unshaken condition (2.46 +- 0.17 percent). Since mortality is low even at 20 X 10~3 ind centre dot l~(-1), this can still be used to transport S. serrata zoeae for 6 h. However, loading density should be reduced to 10X 10~3 ind centre dot l~(-1) for transport duration up to 12 h.