Abstract

The River Murray crayfish, Euastacus armatus, has suffered a considerable reduction in range and abundance over the last 50 years and is now absent from the lower River Murray in South Australia. Environmental degradation and overfishing both may have contributed to this decline. A study on the feasibility of re-establishing E. armatus populations has involved survivability and tolerance studies, establishing a pilot hatchery and nursery for the production of on-grown juveniles and investigating the genetic structure of the species. In the laboratory, juvenile E. armatus showed short term tolerance, expressed as LC₅₀. values, to dissolved oxygen concentrations of 2.2 mg l^-1, temperatures of 30°C and salinities of >16% and longer term tolerances to dissolved oxygen down to 3 mg l^-1, temperature up to about 27°C and salinities >16%. Adult crayfish survived long tenn caging experiments over periods up to 12 months in the lower River Murray. Berried females held in hatchery tanks produced from 60 to 523 stage 3 offspring. These juveniles were held in outdoor, aerated pools at densities of 10 and 50 m^-2 and grew to mean weights of about 5 g in one year with survival of 41% and 31% respectively. Three populations of E. armatus showed little genetic differentiation suggesting that the species has a high level of genetic continuity. Taken together these studies suggest that re-establishment of E. armatus in the lower River Murray is feasible.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: