Journal of the Royal Society of Western Australia, 87:187-191, 2004 
Introduction of redclaw crayfish Cherax quadricarinatus (von Martens) 
to Lake Kununurra, Ord River, Western Australia: 
prospects for a 'yabby' in the Kimberley 
R G Doupe 1,3 , D L Morgan 2 , H S Gill 2 & A J Rowland 2 
1 Fish Health Unit, Division of Veterinary and Biomedical Sciences, 
Murdoch University, Murdoch, WA 6150. 
2 Centre for Fish and Fisheries Research, Division of Science and Engineering, 
Murdoch University, Murdoch, WA 6150. 
3 Correspondence to Rob Doupe: R.Doupe@murdoch.edu.au 
Abstract 
The recent introduction of redclaw crayfish for aquaculture to the Ord River region of Western 
Australia has been followed by the detection of a 'wild' population in Lake Kununurra. A gut 
survey of the lake's fish fauna was used to estimate the degree of assimilation of redclaw crayfish 
into the lake's food chain, however very few crayfish were found in only two catfish species 
(Ariidae). These results leave us uncertain of whether this low detection rate is due to either low 
numbers of redclaw crayfish in the lake, or that alternative food resources in the lake means that 
predation of redclaw crayfish is either due to opportunism or is of dietary insignificance. A further 
possibility is that the survey was undertaken at a time too soon to allow redclaw establishment and 
assimilation into the lake ecosystem. Whichever, translocating non-endemic freshwater crayfish 
into novel environments inevitably raises the possibilities of competitive interactions between the 
introduced and endemic species, food web alterations via predation and grazing pressure, the 
addition of symbionts, habitat alterations, and disease introductions. An account of how the 
introduction of a non-endemic crayfish causes all or some of these problems is yet to be adequately 
described in Australia, however there is an urgent need for such an assessment and the opportunity 
is now available at Lake Kununurra. 
Keywords: redclaw crayfish; Cherax quadricarinatus ; introduced species; translocation 
Introduction 
The redclaw crayfish Cherax quadricarinatus (von 
Martens) is a physically robust species that grows 
relatively quickly in a wide range of environments (Jones 
& Ruscoe 2001). Redclaw crayfish typically breed 
annually during the spring/summer months, although 
recurrent spawning has been observed in at least some 
females (King 1993; Barki et al. 1997). Females are 
moderately fecund (King 1993; Austin 1998) and incubate 
their eggs until hatching of highly developed juveniles 
Oones et al 2000). 
In Australia, the pre-European distribution of redclaw 
crayfish is thought to be confined to the ephemeral 
catchments of far northern Queensland and the northern 
and eastern parts of the Northern Territory (Riek 1969; 
Curtis & Jones 1995), however the significant aquaculture 
potential of this species (see Jones et al 2000) has resulted 
in them being widely translocated within Australia and 
overseas (Horwitz 1990; Curtis & Jones 1995). There are 
no known native freshwater crayfishes in the Kimberley 
region of Western Australia's far north (Riek 1967,1969; 
Jasinska et al 1993) and redclaw crayfish is classified as a 
restricted fish species for importation into Western 
Australia (Anon 1997). In 1998, the Western Australian 
Department of Fisheries (WADF) introduced a small 
population of the selectively improved 'Walkamin' strain 
of redclaw crayfish (see Jones et al 2000) to a quarantine 
station near the northeast Kimberley town of Kununurra, 
© Royal Society of Western Australia 2004 
to determine its suitability for aquaculture in the Ord 
River Irrigation Area (ORIA). Following a quarantine 
period of about 12 months, the Walkamin stock were 
certified as 'disease-free' by WADF personnel and 
redclaw crayfish aquaculture licences were issued to a 
few farms in the ORIA. In 2000, 'wild' redclaw crayfish 
were first found in Lake Kununurra (R. Doupe unpub 
data; D. Harvey, WADF, pers comm), a Ramsar listed 
irrigation water supply reservoir on the Ord River (Fig 
1). Initial speculation was that the animals had escaped 
from aquacultures in the ORIA, but a comparative 
investigation of the genotypes of Lake Kununurra 
redclaw and a range of redclaw genotypes from 
elsewhere by Greenway & Mather (2000), indicated that 
these animals were not of the 'Walkamin strain, but 
were more closely related to Northern Territory redclaw 
crayfish populations; the exact population has never been 
identified. Who translocated redclaw crayfish to Lake 
Kununurra is unknown, however in the time since their 
detection, officers of the Australian Quarantine and 
Inspection Service have occasionally confiscated redclaw 
crayfish from recreational fishermen attempting to bring 
these animals from the adjacent Northern Territory into 
the Kimberley for use as fish bait (T. Thorne, WADF, 
pers comm). 
There are significant risks associated with the 
movement of aquatic species by human agency. For 
example, translocating freshwater crayfish into novel 
environments raises the possibilities of competitive 
interactions between the introduced and endemic species 
(including epibiotic species associated with the crayfish 
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