Researchers from the University of Texas Rio Grande Valley recently discovered the first known introduction of invasive Australian Redclaw Crayfish (Cherax quadricarinatus) in South Texas, and the consequences of the species spreading across the Lone Star State could be detrimental for local wildlife.
The crayfish — which can be identified by its large size, large left claw with a red patch on the outer edge and four distinct ridges on the top of its head — has only been previously detected in the United States in California, according to a news release from the Texas Parks and Wildlife Department. The species grows rapidly and can reach a maximum size of up to two pounds in under a year.
The Australian Redclaw Crayfish had only been previously detected in the United States in California.
Texas Parks and Wildlife DepartmentThe large crayfish prefer slow-moving streams and stagnant water bodies with high turbidity and can move over land and between waterbodies, per the release. In January and February, specimens were collected at an apartment complex pond that connects to a nearby resaca in the Brownsville area. Three additional Australian Red Crayfish were spotted two miles away from the site in July.
Dr. Archis Grubh, an aquatic biologist with TPWD, is calling on the public to report sightings of the invasive species to better understand where it's distributed in the state and potentially take steps to prevent its spread. "We don't know when these invasive crayfish were first introduced or how far they spread, but we do know they can have a negative effect on local species and biodiversity," Grubh said.
Both male and female Australian Redclaw Crayfish have been collected, so the potential for reproduction is a concern, TPWD said in the release. The species can reproduce prolifically, with females brooding up to five times a year at 1,000 eggs per clutch. They can also be easily spread to new areas through rainfall washing them across waterbodies.
Per the agency, the large crayfish can significantly alter habitat and vegetation, competitively exclude native crayfish, and can impact native fish communities by direct predation. The species can also carry Crayfish Plague and other parasites and diseases that could impact native crayfish.
Some hungry Texans have already expressed intentions to hunt the crayfish for food. "Tell the Cajuns where they are and they'll be gone in a month," read one comment on TPWD's Facebook post announcing the crayfish. "A 2lb crawfish! How long do you boil those for?" asked another.
Kirk McDonnell with TPWD said in an emailed statement that crayfish in general, including the Australian Redclaw, are good to eat. "The Australian Redclaw crayfish is used in aquaculture industry elsewhere for human consumption, but TPWD has banned its possession and sale in the state of Texas due to its potential impact on native fauna and flora," he wrote.
It's also illegal to release the crayfish into a public body of water, a key means of which the invasive species is introduced, according to Monica McGarrity, a TPWD senior scientist for aquatic invasive species.
"Well-meaning, uniformed aquarium owners sometimes release their pets thinking they're doing the best thing for them, but if they do survive, they can become invasive and harm the native aquatic species and ecosystem," McGarrity said in the release. "Aquarium owners should research alternatives to aquarium dumping and help prevent introductions of the next invasive species."
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