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ABSTRACT In this study tetraploid Marsupenaeus japonicus (Bate) embryos were produced by preventing the first division in mitosis. The effectiveness of temperature and chemical shocks for producing tetraploid M. japonicus [...]

The effects of the blooms of the cyanobacterium Trichodesmium spp. on penaeid prawn larvae were studied through in situ and laboratory rearing experiments and plankton surveys in Albatross Bay, Gulf of Carpentaria, Australia. In situ experiments revealed that larvae of the prawn Penaeus merguiensis did not develop beyond the first protozoa stage during a bloom of Trichodesmium spp. Results indicated that variations in both timing and magnitude of Trichodesmium blooms are significant indicators of prawn larvae abundance in Albatross Bay.

Larval abundance, phytoplankton community structure and chlorophyll a concentration was studied among the larval species of Penaeus merguiensis in Albatross Bay, Gulf of Carpentaria. It was shown that the main diet of the larvae consist of diatoms, green algae and seagrass detritus. Furthermore, it was shown that the diatom flora of the bay can sustain the prawn larvae even during seasonally low levels and therefore is not responsible for the mortality of the species during those periods.

Abstract The present study compares the relative costs of stocking ponds with postlarvae from wild or domesticated Kuruma shrimp, Penaeus japonicus (Bate), broodstock. Wild broodstock were obtained from a commercial trawler. Domesticated broodstock were reared to harvest size (wet weight = 25 g) on a commercial farm and then transferred to controlled environment tanks where they were grown to a final wet weight of 50 g. The costs of stocking ponds with postlarvae were calculated from the observed reproductive output, the costs of purchasing wild broodstock and the costs of domesticated broodstock production in the controlled environment facility. Domesticated P. japonicus spawned comparable numbers of eggs to wild broodstock of similar size, but hatching success was significantly lower. A total of 12 domesticated P. japonicus broodstock would be needed to produce the postlarvae to stock a 1-ha pond, compared to only six wild broodstock. However, the much higher relative costs of wild broodstock means that the cost of using their postlarvae would be Aus$851 per pond compared to Aus$390 for domesticated broodstock. The present authors conclude that the use of domesticated P. japonicus broodstock could be a cost-effective alternative to wild broodstock in Australia and in other countries where P. japonicus is farmed. [ABSTRACT FROM AUTHOR]

Develops strategies for sampling sediment bacteria in intensive shrimp ponds in Australia. Comparison between the bacterial counts of the pond center and the pond periphery; Correlation between the bacterial numbers in the sediment and the sediment grain size; Role of bacteria in nutrient cycling; Association between nitrogen concentration and bacterial numbers in pond sediments.

Describes an automated spawning detection and alarm system that permits timely collection and manipulation of penaeid shrimp embryos. Components of the alarm system; Applications for multiple spawnings; Effectiveness of the system in detecting spawnings of penaeids and a range of aquatic species that release eggs or embryos directly into the water.