JOURNAL OF THE Vol. 40, No. 6 WORLD AQUACULTURE SOCIETY December, 2009 Temperature and Salinity Tolerances of the Tropical Spiny Lobster, Panulirus ornatus Clive M. Jones 1 Department of Primary Industries and Fisheries, Northern Fisheries Centre, PO Box 5396, Cairns, Queensland 4870, Australia Abstract Interest in the development of aquaculture of the tropical spiny lobster, Panulirus ornatus, has increased markedly over the past 10 yr because of strong market demand and high prices. In Australia, economic conditions will necessitate that a semi-intensive approach be taken, possibly involving managed environmental conditions. Identification of optimal temperature and salinity levels will be necessary, and therefore two experiments were performed to examine these two parameters. Juvenile lobsters were grown in tanks at five temperatures (19, 22, 25, 28 and 31 C). Growth was significantly affected by temperature (P< 0.01), and maximal growth occurred at 25–31 C. Examination of the temperature effect on molt increment and intermolt period indicated that 27 C was the optimal temperature, at which molt increment was greatest and intermolt period the least. Temperature also had a significant (P< 0.01) positive effect on apparent feed intake (AFI). Juvenile lobsters were also exposed to four different salinities (20, 25, 30 and 35 ppt) over a period of 91 d. Significant differences (P< 0.01) were apparent for both survival and growth. Lowest survival occurred at 35 ppt which may be attributable to higher cannibalism at that salinity. Growth was highest at 35 ppt and progressively less at lower salinities. Although full marine salinity (35 ppt) will generate best performance of P. ornatus, its capacity to tolerate reduced salinity will provide greater opportunity to develop commercial aquaculture. A small but valuable fishery for the tropical spiny lobster, Panulirus ornatus, exists on the northeast coast of Australia. Between 500 and 1000 ton of live lobster are caught each year and are supplied to eager markets in mainland China, where they are primarily consumed as a sashimi (uncooked) product. The fishery is well managed and fully exploited (Dennis et al. 2004), so increasing demand for the species can only be supplied from aquaculture. In Vietnam, this species is successfully cul- tured in sea cages from wild-caught juveniles (Williams 2004). This low technology approach is effective under the prevailing economic con- ditions; however, in Australia, higher costs for labor and legislative compliance will necessi- tate a more intensive culture method, possibly including managed environmental conditions. This will necessitate a sound understanding of the environmental and biological requirements of the species and identification of optimal con- ditions, which maximize growth and survival. 1 Corresponding author. Temperature and salinity are likely to be two of the more important environmental factors, and each was examined through individual experiments to determine optimal levels and tolerances. As temperature is directly correlated with growth rate (Hartnoll 2001), to a point beyond which growth rate continues to rise, but mortality increases substantially, optimal tem- perature must be identified as that at which growth is maximized relative to survival. For salinity, identification of a capacity to withstand less than fully marine salinities may provide a significant expansion of potential sites and sys- tem requirements for commercial cultivation. Materials and Methods These experiments were performed at the aquaculture facilities of the Northern Fisheries Centre, Cairns, in northeast Australia. Exper- imental lobsters were sourced from the wild either by hand collecting from wharf pylons in Trinity Inlet, Cairns, or from artificial shelters deployed at various sites along the coast in the  2009 The State of Queensland (through the Department of Employment, Economic Development and Innovation) 744