Ž .
edwardsii. Lobsters held at this temperature showed reduced survival compared to those at 188C , Ž
. reduced growth compared to those at 228C and appeared to be suffering from respiratory stress
Ž .
moult-related mortalities, low Q between 228C and 248C . Overall, the results indicate that
10
juvenile J. edwardsii can be cultured at 228C without adversely affecting their growth, survival or feed efficiency with optimal temperature range between 19 and 218C. q 2000 Elsevier Science
B.V. All rights reserved.
Keywords: Jasus edwardsii; Temperature; Growth; Respiration; Feed conversion ratio; Ammonia excretion
1. Introduction
The southern rock lobster, Jasus edwardsii, forms the basis of an important fishery in southern Australia and New Zealand. Research has shown that the Australian and New
Ž .
Zealand stocks are the same Booth et al., 1990 . J. edwardsii commands a high market price, identifying them as a potential aquaculture species. Typical of most spiny lobsters,
they have a long and complex early life history. The planktonic phyllosoma stage is spent dispersed by oceanic currents for a period of 8–16 months before settling as
Ž .
puerulus in shallow coastal waters Kennedy, 1990 . Presently, it is not feasible to commercially produce puerulus in hatcheries; therefore, initial industry development is
focussing on the collection and ongrowing of recently settled puerulus. One of the important variables that will affect the efficiency of J. edwardsii culture is temperature.
Temperature is one of the major environmental factors affecting the growth of Ž
. crustaceans reviewed by Hartnoll, 1982 . Growth rate has been shown to increase with
increasing temperature to a maximum, before declining near the upper thermal limits Ž
. Chittleborough, 1975 . Elevated temperature could potentially reduce the culture period,
Ž which would be important for the economic viability of J. edwardsii culture Hooker et
. al., 1997 . The optimum temperature range suggested for culture of J. edwardsii is
Ž .
between 18–208C Booth and Kittaka, 1994 . However, considerable variation in results has been obtained at similar temperatures. It is unclear whether this variation is a result
Ž of different husbandry practices or from intraspecific variations Sastry and Vargo,
. Ž
. 1977 . For example, Bunter and Westaway 1993 found reduced survival of juvenile
Ž .
lobsters at 188C compared to lower ambient temperatures 10–168C in Tasmania. Ž
. However, Manuel 1991 found that 188C did not adversely effect survival of the same
species collected in southern New Zealand. Previous studies also indicated that growth Ž
. Ž
. rate was reduced at 228C Hollings, 1988; Manuel, 1991 ; while Hooker et al. 1997
reported increased mortalities associated with water temperatures of 23.38C. Defining the upper thermal limits will be important for site selection and the most appropriate
culture temperature. In addition, few data are available on the influence of temperature on feed consumption, food conversion ratio, oxygen consumption or ammonia excretion
of juvenile J. edwardsii. This will have important implications for culture in regards to feeding costs and systems management.
The aim of this study was to determine the effect of elevated temperature on survival, growth, feeding, oxygen consumption and ammonia excretion of post-puerulus J.
edwardsii, and to identify the upper thermal limit and the most efficient temperature for culture.
2. Materials and methods
