The combined effects of
temperature and salinity on growth and survival of juvenile mud crabs (Scylla
serrata Forskål)
I.M. Ruscoe, C.C. Shelley, G.R. Williams-2004
Aquaculture, 238: 239-247
Abstract:
An experiment was conducted to determine the effects
of temperature and salinity on the growth and survival of the mud crab Scylla
serrata, and the combined optima for these parameters during the nursery
phase. Instar 2 crablets, mean weight 18.43±0.42 mg were individually
reared at combinations of temperature (20, 25, 30, and 35 °C) and salinity
(0‰, 5‰, 10‰, 20‰, 30‰, and 40‰) for 18 days. Crablets were fed
an artificial penaeid diet to satiety each day and at harvest were weighed,
and the carapace width was measured. All crablets held at 0‰, regardless
of temperature, were dead the morning after stocking and were therefore
excluded from any data analysis. Survival was significantly different among
treatments due to temperature but not due to salinities between 5‰ and
40‰. The mean survival for the various temperatures were 36.0%, 98.0%,
96.0%, and 94.0% for temperatures of 20, 25, 30, and 35 °C, respectively.
Growth, as measured by individual wet weight at harvest, carapace width,
instar 3 intermoult duration, and weight-specific growth rate (WSGR
percentage per day), was influenced more by temperature than by salinity,
although both had significant effects on all parameters examined. Analyses
indicate that maximum WSGR of around 16% day−1 was achieved
at 30 °C and 10–20‰ salinity. Based on the findings of this experiment,
S. serrata juveniles from the Northern Territory of Australia should
be reared at approximately 30 °C with salinities in the range of 10–25‰
in order to achieve maximal production.
(Darwin Aquaculture Centre, Fisheries Group,
Department of Business, Industry and Resource Development, GPO Box 3000,
Darwin, NT 0801, Australia, e-mail: ian.ruscoe@nt.gov.au)