Eggs and
hatchlings of the freshwater crayfish, marron (Cherax tenuimanus
Smith), can be artificially incubated at high population densities, and are
most successfully incubated at water temperatures between 20°C and 24°C
M. Henryon, I.W. Purvis-2003
Aquaculture
Research, 34(14):
1311-1320
Abstract:
This study tested two premises. First,
that there is a range in water temperature within which to artificially
incubate marron eggs and hatchlings, which enables a combination of rapid
development, high survival, and the production of large juveniles. Second,
that the population density of marron eggs and hatchlings incubated
artificially can be increased without altering development time, survival,
or juvenile body weight. Marron eggs were collected from 31 gravid females
and artificially incubated at four water temperatures (i.e. 16°C, 20°C, 24°C,
28°C), while eggs were collected from eight females and artificially
incubated at three population densities (i.e. 0.35, 0.70, 2.80 eggs mL-1).
The eggs and hatchlings were assessed for development time and survival as
they hatched and developed into juveniles. The juveniles were weighed at the
conclusion of the incubation period. As water temperature was increased from
16°C to 28°C, there was an inverse curvilinear relationship between
development time and water temperature, the time required for the eggs to
hatch and develop into juveniles decreasing from 70.2 to 24.5 days. However,
at 16°C and 28°C, the survival of the eggs and hatchlings was reduced
(i.e. 83.8% and 87.7% at 20°C and 24°C vs. 70.4% and 57.5% at 16°C and 28°C),
while incubation at 28°C resulted in the development of small juveniles
(i.e. 29.7, 29.2, and 28.5 mg at 16°C, 20°C, and 24°C vs. 25.1 mg
at 28°C). In comparison with water temperature, increasing the population
density of the eggs and hatchlings from 0.35 to 2.80 eggs mL-1
did not have a significant effect on development time, survival, or juvenile
body weight. The two premises tested in this study were supported,
demonstrating that marron eggs and hatchlings can be artificially incubated
at high population densities, and are most successfully incubated in water
maintained between 20°C and 24°C.
(Department of Animal Breeding and
Genetics, Danish Institute of Agricultural Sciences, Research Centre Foulum,
PO Box 50, 8830 Tjele, Denmark, E-mail: Mark.Henryon@agrsci.dk)