Photographers: E. Cortés, H. Villarreal, and R. Civera. Affiliation: Aquaculture Advocate Copyright: (CC BY 3.0)
Cherax quadricarinatus can easily grow up to 12 inches in length and ranges from dark brown to blue-green; with “quadricarinatus” referring to four keels on the head. This crayfish received the common name “redclaw” because adult males have a soft, fleshy, bright red patch on the outer margin of the major chelae (claw). Females, which are smaller than males, spawn hundreds of olive-green eggs per brood, kept on the underside of her tail until they hatch.
The Australian Redclaw Crayfish is a prohibited species to sell in Texas.
Since researchers found both males and females in south Texas, they worry about a population explosion. Redclaws reach maturity and weigh around two pounds within a year. Their size and rapid reproduction rate allow them to outcompete native species, possibly overtaking food sources and disrupting local ecosystems. The redclaw, competes with native crayfish for food and other resources and preys on native fish as well as alters the native habitat. The redclaw can carry viruses, bacteria, fungi and the crayfish plague against which local crayfish have no immunity; most notably it is a vector of white spot syndrome virus (WSSV) and crayfish plague. WSSV caused heavy mortality in Louisiana crayfish farms during a 2007 outbreak, and although native North American crayfish are less susceptible to crayfish plague, high-stress conditions increase the disease and mortality rate of native crayfish.
Females can breed almost all year long and can lay up to 1,000 eggs three to five times a year. Eggs go through several identifiable stages with changes in color and appearance of body structures in the developing embryo. The time of development changes with water temperature. Fertilized eggs stay situated on the underside of the tail on the female’s pleopods. Incubation takes about six weeks, and the newly hatched juveniles rapidly become independent. Juveniles emerge from the eggs and like adults, they can crawl over land to spread their territory. However, Texas Parks and Wildlife stipulates the main mode of expansion is with flood washes from seasonal rains.
Due to its large size, this species has been imported for consumption to various countries, including Mexico (1990s). Flooding events and its ability to crawl well over land, allowed it to escape captivity. Introduced populations have been documented throughout the Mexican border state of Tamaulipas via researchers (2017-2018) and iNaturalist (2022) as close as 125 miles away from Brownsville, TX. However, the first U.S. sighting was in December 2018 at Lake Balboa. Los Angeles when a crayfish was unintentionally caught via hook and line by a researcher. Subsequently, a scouring of social media platforms showed sightings at Lake Balboa from November 2018- May 2019; along with an iNaturalist post from 2013 documented female and its young in a Brownsville, TX apartment complex near a temporary pond or "resaca". TPWD performed sampling near that apartment complex in 2022 and captured 3 individuals.
Currently, TPWD is funding a survey by UT-Tyler in the Brownsville area.
Northeastern Australian and Papua New Guinea
Habitat: They are found in freshwater creeks and water bodies. Primarily bottom dwellers, the species prefers to hide in crevices or under rocks and debris in the water. Humans would need to search closely to encounter them.
U.S. Present: Confirmed reports from: CA, NV, PR & TX. Thoroughly established in Puerto Rico.
If you believe you see one, please email a picture of the animal and its location to aquaticinvasives@tpwd.texas.gov.
Texas: Brownsville, TX found in 2022
It can be confused with native crayfish, in particular the Red Swamp Crayfish in its blue morph (Procambarus clarkii) and the Painted Devil Crayfish (Lacunicambarus ludovicianus). However, no native species possess the red patches on the outer margin of the claws.
The Australian Redclaw Crayfish, along with all other members of the crayfish Family Parastacidae, are prohibited exotic species in Texas and cannot be legally purchased, sold or possessed in aquariums. It’s also illegal to release these crayfish into a public waterbody.
Physical: Intensive trapping is a common method used to control crayfish. However, trapping has not been found to completely eradicate established crayfish populations.
Chemical: Cypermethrin is a commonly used piscicide for crayfish control.
Text References
Coughran, J., and S. R. Leckie. 1997. Invasion of a New South Wales stream by the tropical crayfish, Cherax quadricarinatus (von Martens). Pest or Guest: the zoology of overabundance:40-46.
Edgerton, B.F., R. Webb, I.G. Anderson, and E.C. Kulpa. 2000. Description of a presumptive hepatopancreatic reovirus, and a putative gill parvovirus, in the freshwater crayfish Cherax quadricarinatus. Diseases of Aquatic Organisms 41:83-90.
García Vázquez, S. 2008. Distribution of exotic Australian crayfish Cherax quadricarinatus (Von Martens, 1868) in Puerto Rico. Unpublished M.S. thesis. University of Puerto Rico, Mayagüez Campus, Mayagüez, PR.
Haubrock, P.J., F.J. Oficialdegui, Y. Zeng, J. Patoka, D.C.J. Yeo, and A. Kouba. 2021. The redclaw crayfish: A prominent aquaculture species with invasive potential in tropical and subtropical biodiversity hotspots. Reviews in Aquaculture 13(3):1488-1530.
Hauck, A.K., M.R. Marshall, J.K.K. Li, and R.A. Lee. 2001. A new finding and range extension of bacilliform virus in the freshwater redclaw crayfish in Utah, USA. Journal of Aquatic Animal Health 13:158-162.
Hyatt, M.W. 2004. Investigation of crayfish control technology. Final report (No.1448-20181-02-J850) to Arizona Game and Fish Department.
Moorhouse, T. P., Poole, A. E., Evans, L. C., Bradley, D. C., and D. W. Macdonald. 2014. Intensive removal of signal crayfish (Pacifastacus leniusculus) from rivers increases numbers and taxon richness of macroinvertebrate species. Ecology and Evolution 4(4):494-504.
Peay, S. 2009. Invasive non-indigenous crayfish species in Europe: recommendations on managing them. Knowledge and Management of Aquatic Ecosystems 3:394-395.
Sanjar, A., D.R. Davis, and R.J. Kline. 2023. Evidence of an established population of Cherax quadricarinatus (von Martens, 1868) in south Texas, USA. BioInvasions Records 12(1):284-291. https://www.reabic.net/journals/bir/2023/1/BIR_2023_Sanjar_etal.pdf.
U.S. Fish and Wildlife Service. 2012. Australian redclaw (Cherax quadricarinatus): ecological risk screening summary. U.S. Fish and Wildlife Service.
Williams, E.H., Jr., L. Bunkley-Williams, C.G. Lilyestrom and E.A.R. Ortiz-Corps. 2001. A review of recent introductions of aquatic invertebrates in Puerto Rico and implications for the management of nonindigenous species. Caribbean Journal of Science 37(3-4):246-251. http://www.biology.uprm.edu/facultad/publications/Lucy_Bunkley_20010101_5.pdf.
Zeng, Y., K.K. Shakir, and D.C.J. Yeo. 2019. Competition between a native freshwater crab and an invasive crayfish in tropical Southeast Asia. Biological Invasions 21:2653-2663.
Internet Sources
https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?Species_ID=220&Potential=Y&Type=2
https://www.fws.gov/sites/default/files/documents/Ecological-Risk-Screening-Summary-Redclaw.pdf.
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