Good kreef! Crayfish have high-tailed it to Free State

A thriving population of highly invasive‚ alien crayfish has been found living in a dam in the Free State‚ prompting concern from environmentalists.

Unlike the prized west coast rock lobster found along the coast‚ the red swamp crayfish is considered a pest due partly to its habit of burrowing into muddy embankments – including dam walls – and dislodging indigenous species.

While it is unlikely to encounter too many rival crayfish in the Free State‚ the red swamp crayfish could also disrupt aquatic ecosystems‚ the Department of Environmental Affairs said on Wednesday.

“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 the public‚” the department said in a statement.

Officials caught 53 mostly juvenile crayfish in the dam during two sampling surveys in June. The presence of adults suggests the species is well established.

“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‚” the department said.

“According to reports received‚ there are people in the [Free State] Goldfields area that catch these crayfish and then sell them for R10 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 R10m and/or a prison sentence upon conviction.”

The invasive species has wreaked havoc elsewhere in the world‚ notably in Europe where it has decimated indigenous species. Freshwater crayfish do not occur in Africa.

Red swamp crayfish is used for aquaculture and the pet shop trade.