Murray Crayfish

Scientific name

Euastacus armatus

Status in NSW

Vulnerable

Characteristics

Murray Crayfish have characteristic white claws and three rows of large white spines on each side of the tail. Males generally have larger claws while females have broader abdomens. Individuals have a dark green to green-brown body.

Species similar in appearance

Other Euastacus species.

Size

The species grows to more than 150 mm in carapace length; with the maximum recorded size being 174 mm and 2.5 kg. The Murray Crayfish is the largest of over 40 species in the genus Euastacus which represents freshwater 'spiny' crayfish.

Did you know?
The Murray Crayfish is the second largest freshwater crayfish in the world!

Murray Crayfish (Photo: E. Lake)

Distribution

The Murray Crayfish is endemic to the southern tributaries of the Murray-Darling Basin. It historically occurred in New South Wales, Victoria, South Australia and Victoria but has seen significant declines throughout its range.

Habitat

Murray Crayfish prefer cool, flowing water that is well oxygenated. The species is tolerant of water temperatures up to 27°C and moderate salinities, but are intolerant to low dissolved oxygen concentrations. They create burrows that vary in complexity, from deep burrows with multiple entrances to simple burrows under a rock or log

Image credit Maryrose Antico

Why is the Murray Crayfish threatened?

Habitat modification from the construction of weirs
River regulation which in turn alter water temperatures
Sedimentation can fill deeper holes, smother snags and bury clay banks required for burrowing
Historic overfishing and current illegal fishing practices remove individuals from a population
Pollution and pesticide run off into rivers
Extreme weather events such as flooding can create blackwater events which can be devastating to a population
Competition with and predation by introduced species
Local extinctions may not be naturally recolonised because of the species' inability to disperse the long distances required