STATUS OF THE POTENTIALLY INVASIVE AUSTRALIAN REDCLAW CRAYFISH (CHERAX QUADRICARINATUS)

The introduction of invasive species, including crayfish, is common through aquaculture and aquarium trade pathways and is an important factor causing the decline and/or extinction of native species. Invasive species cause billions of dollars in damages annually and threaten almost half of the native species in the United States. Australian Redclaw Crayfish (Redclaws) are a species of large individuals that originated in Australia and New Guinea and have been introduced specifically for aquaculture and the aquarium trade. Redclaws are known to thrive in tropical and subtropical locations. They can tolerate high temperatures and low oxygen and are generalist omnivores that are also known to be capable of overland movement. Redclaws can reach sexual maturity in less than a year. Females can produce up to 1,000 eggs and may reproduce multiple times within a year, up to five times in ideal conditions. They are known to be ecosystem engineers, altering nutrient cycling, food webs, and habitats, and directly and indirectly compete with and even cause the decline of native species. Based on these characteristics, Redclaws have the potential to become established, spread, and have harmful impacts if environmental conditions are met. This study describes the current distribution and habitat use of Redclaws in South Texas. A total of 43 sites were sampled over the course of 13 months, with over 100 Redclaws collected during this study period. Water quality and habitat descriptions also were recorded. Statistical analyses were conducted to help assess and predict the establishment and spread of Redclaws in south Texas. The most consistent predictors of Redclaws presence were temperature, resaca, conductivity, and dissolved oxygen with increased detection probabilities connected to warmer temperatures and higher dissolved oxygen. Spatial prediction of suitable habitat indicates areas north of Brownsville could support Redclaws populations if they were to migrate north, which is concerning because of the number of Species of Greatest Conservation Need that are located there; however, dispersal simulations suggest that it is unlikely. This study will serve as a baseline to support future studies on the long-term impacts of the Redclaws on Texas’ invaded aquatic ecosystems.