Discovery of alien and highly invasive freshwater crayfish in the Free State Goldfields

15 August 2018

red swamp crayfish

The Department of Environmental Affairs (DEA) is working closely with the Free State Department of Economic, Small Business Development, Tourism and Environmental Affairs (FS DESTEA) as well as the local and district municipalities in the Goldfields area to eradicate and stop the spread of red swamp crayfish which was discovered in the Free State. The species is alien and considered to be highly invasive.

Acting on a tip off from a member of the public in Welkom, Dr. Leon Barkhuizen, Aquatic Scientist from the FS DESTEA, discovered a large population of alien and highly invasive red swamp crayfish, Procambarus clarkia, in a dam in the Free State Goldfields. The identification of the species was confirmed by Professor Linda Basson from the Department of Zoology and Entomology at the University of the Free State. The reason for the presence of this alien and highly invasive species in the dam is not clear, but anecdotal reports indicate that it might have been released by members of the public.

During two sampling periods in June 2018, Dr. Barkhuizen caught 53 individuals of which most were juveniles ranging between 2 and 10 cm in length as well as a few adults. From the preliminary results it is clear that it’s an established and breeding population due to the large number of juveniles that were collected. It seems that the crayfish have been present in the area for quite a number of years, considering that two large individuals were found in a swimming pool in the area in October 2017.

Freshwater crayfish do not naturally occur in Africa and a large number of species occur in Europe, America and Australia. The red swamp crayfish, also known as the Louisiana crayfish that was discovered in the Goldfields is indigenous to northern Mexico and south-east United States of America. The species has spread throughout the world, mostly for aquaculture purposes and the pet shop trade.

In many countries the red swamp crayfish has escaped into natural environments where it has decimated indigenous crayfish species and other aquatic organisms and caused irreparable damage to aquatic systems. It is also the carrier of the highly infectious crayfish plague which has wiped out indigenous crayfish species, especially in Europe. The red swamp crayfish grow very fast and start to reproduce at lengths of 40 cm. The females may carry up to a few thousand eggs at a time. Adults dig tunnels with depths between 30 to 90 cm where mostly adults and females with young stay. Due to this digging behaviour, it holds a threat especially for irrigation channels and dams.

In South Africa the red swamp crayfish has been listed on “List 10: Prohibited freshwater Invertebrates”, Alien and Invasive Species regulations of 14 August 2014. According to the regulations, a permit to possess these crayfish in South Africa may not be issued as contemplated in Section 67 (1) of the National Environmental Management: Biodiversity Act. Prescripts in the Act also requires for the immediate eradication of this species where it is found. According to reports received, there are people in the Goldfields area that catch these crayfish and then sell them for R10,00 each. This action must be stopped immediately to prevent the further spread of this highly invasive species. According to the legislation, it is an offence to be in possession of the red swamp crayfish and if a person is found to be in possession, such a person can be fined up to R10 million and/or a prison sentence upon conviction.

Various meetings and onsite inspections will be done in the next coming weeks to determine the exact extent of this invasion. People in possession of red swamp crayfish should immediately contact the officials mentioned below and under no circumstances should they be released into the environment or given to any person.

A website that can provide a detailed list with images of: various invasive species; which ones are totally prohibited, which ones can be permitted and how to apply for such a permit is available through this link » Invasive Species South Africa

If the public in the Goldfields area is aware of any person selling these red swamp crayfish, such information should be reported immediately to:

Dr. Leon Barkhuizen
Cell: 083 256 9446 or

Ms. Trudell Potgieter
Cell: 012 399 9971
E-mail: tpotgieter@environment.gov.za

For media enquiries please contact:
Zolile Nqayi
Cell: 082 898 6483
E-mail: znqayi@environment.gov.za