Crayfish in South Africa: Species, Environmental Impact, and Regulations

Dec 01, 2025 0

The introduction of alien freshwater crayfish into regions outside their native range has led to negative impacts on biodiversity and human well-being. This has necessitated the need to control and manage their movement and utilization, partly through risk analysis protocols.

Continental Africa has no native freshwater crayfish species. Over the years, mostly because of aquaculture practices and the aquarium trade, humans have introduced crayfish species in areas beyond their native ranges. Many of these species survived and now thrive in areas where they were not supposed to exist.

Procambarus clarkii, the red swamp crayfish, is a notable invasive species in South Africa.

Invasive Crayfish Species in South Africa

Several alien crayfish species have been introduced into Africa. Three are originally from Australia: the Australian redclaw crayfish (Cherax quadricarinatus), the smooth marron (Cherax cainii) and the yabbie (Cherax destructor). These three species were introduced into South Africa during the 1970s for aquaculture purposes. From there they were translocated to Zambia.

One species has already caused enormous problems in Kenya. Another is threatening the Okavango Delta, which is a World Heritage Site. Crayfish interlopers slow down plant growth, eat rice seedlings and can even make dams’ banks collapse.

The red swamp crayfish (Procambarus clarkii) is native to North America. It has been introduced into Uganda, Kenya, Egypt, Zambia, Sudan and South Africa.

A concerning new discovery was made in Vredendal where the North American Red Swamp Crayfish (Procambarus clarkii) was detected in the Lower Olifants River irrigation system. The crustacean is a notorious invader of many countries worldwide and can have negative ecological and economic impacts.

The introduction and spread of any alien species into a new region threatens native communities. Alien species can act as novel predators, competitors and parasites, and they can carry diseases. They may also breed with indigenous species.

The crayfish managed to spread over the lake in a very short time, almost totally destroying its floating and submerged aquatic plants. These plants had provided food and refuge for fish and other aquatic animals. The crayfish also decreased native populations of snails and freshwater crabs from adjacent rivers. Fishermen’s livelihoods were affected too. The crayfish ate fish caught in gill nets, getting entangled in or destroying the nets and disturbing the reproductive and breeding activity of many bottom-spawning species. This crayfish is now present in large areas of Kenya.

A prospective aquaculturist applied to farm this species in South Africa and was turned down by the authorities. He managed to get permission for his venture in neighbouring Swaziland. Several rivers make their way through Swaziland before re-entering South Africa. It was exactly through one of these - the Komati river - that the redclaw crayfish made its way into South African freshwaters about 16 years ago.

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The crayfish is now present in a large part of the eastern Mpumalanga province and in some scattered locations elsewhere in South Africa. In Zambia it mainly exists on the Kafue Flats and in Lake Kariba. An isolated population was recently reported spreading on Zambia’s Barotseland floodplain. There is an extremely high risk of this population spreading to the Okavango Delta, with potentially disastrous consequences to this World Heritage Site.

Another species that bears mentioning is the marbled crayfish or “Marmokrebs” (Procambarus fallax). It was introduced to Madagascar for mysterious reasons, but there may be a link with a road building project carried out by foreign contractors in 2003/2004. In 2005, biologists at the University of Antananarivo noticed it being sold in markets close to the capital.

This particular crayfish has a peculiar history: nobody knows where it comes from. It simply appeared in the German aquarium trade in about 1995. It is also the only decapod in the world known to be able to reproduce by parthenogenesis - a female is able to reproduce without being fertilised by a male. This means that a single individual is sufficient to start a whole new population.

Ecological Impacts of Invasive Crayfish in a Naïve Riparian System

Ecological and Socio-Economic Impacts

The spread of this invasive crayfish not only poses ecological impacts - by altering river morphology, consuming and degrading macrophytes, invertebrates and fish communities - but also socio-economic impacts estimated to cause losses in fisheries of up to US$512 352 per year in e.g. Lake Kariba, Zimbabwe.

Freshwater crayfish are carried downstream by currents. They can also swim or even walk upstream. Human beings use them as fishing bait for bass, for aquaculture and for sale. Some people keep them as pets.

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Environmental and Socio-economic Impact Classification

Recently developed protocols have been used to assess potential current and future impacts of introduced crayfish in South Africa. These include the Environmental Impact Classification Scheme for Alien Taxa (EICAT) and the Socio-economic Impact Classification Scheme for Alien Taxa (SEICAT) for assessing environmental and socio-economic impacts and the Risk Analysis Framework for Alien Taxa (RAAT).

EICAT and SEICAT Assessments

The EICAT and SEICAT assessments indicated that only three species (21%): red swamp crayfish (Procambarus clarkii), rusty crayfish (Faxonius rusticus), and signal crayfish (Pacifastacus leniusculus) had documented environmental impacts in their alien range. The remaining 11 species (79%) had no documented evidence of impacts and were classified as Data Deficient (DD), such that a closely related species with similar traits (e.g., feeding behaviour) and documented evidence of impact was used to infer their potential impacts.

Most environmental impacts were associated with competition, predation, the transmission of diseases, and structural changes to ecosystems. Their magnitude varied from minor to massive.

SEICAT assessments were also affected by a general lack of socio-economic data in the alien range, and most socio-economic impacts were associated with transmission of diseases, disruption in recreational activities, and the compromisation of employment opportunities, with the magnitude varying from minor to moderate.

RAAT Framework

The RAAT framework was then used to assess the potential risk of the 14 alien freshwater crayfish species that have been introduced outside their native range. Of these, species (86%) pose a high-risk of invasion into South Africa, of which four species, marron (Cherax cainii and C. tenuimanus), P. clarkii, and redclaw crayfish (Cherax quadricarinatus) are already present in the country, but they have different introduction status.

Cherax cainii and C. tenuimanus are present but not established.
Procambarus clarkii is established but not invasive.
Cherax quadricarinatus is invasive.

Based on their introduction status and ecological traits, the ease of management for each of these species was scored as medium.

Permit records indicate that C. cainii and C. tenuimanus are likely confined to aquaculture facilities. The current known distribution of P. clarkii in the wild is localised to two localities within Mpumalanga and Free State Provinces. Therefore, eradication is highly feasible.

Cherax quadricarinatus is already widespread in the Inkomati River and adjacent river systems in Mpumalanga Province and is still spreading, and the most appropriate control is to minimise its further spread.

Recommendations from the risk analyses of 5 species do not agree with the current listing under the South African Alien and Invasive Species (A&IS) Regulations because of no occurrence data in the country.

Regulations and Management

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.

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.

The question is how to manage these populations. African countries need to develop better strategies to prevent further spread and to reduce the possible impacts of invasion. More stringent legislation and more scientific research will also be crucial. If these species keep spreading unchecked, the future of Africa’s freshwaters doesn’t look bright.

Eradication efforts are underway to manage the spread of invasive crayfish in South Africa.

General Marine Recreational Fishing Regulations

Here are some general regulations for marine recreational fishing:

No person shall, except on authority of a recreational permit obtainable from the South African Postal Services, engage in recreational fishing.
No person shall sell, barter or trade any fish caught through recreational fishing.
No recreational fishing permit is transferable from one person to another.
A persona of a recreational permit shall not use any artificial breathing apparatus, other that a snorkel.
No person shall, engage in fishing, collect or disturb any fish by means of a gaff, club, flail, stick, stone or similar implement.
No person shall engage in fishing, except for octopus, cuttlefish or squid, by the jerking of a hook or jig in the sea jigging), with the intention of impaling the fish thereon.
No person shall engage in the fishing, collection or disturbing of any fish with a speargun in a tidal river or tidal lagoon.
No person shall use any cast net for fishing from sunset to sunrise.
No person shall disturb, catch, kill or be in possession of any dolphin or any part or product derived thereof.
No person shall, except with the authority of a permit, disturb, catch or kill any whales at any time, or approach closer than 300 m to a whale.
No person shall, except with the authority of a permit, attract by using bait or any other means, any great white shark, or catch, attempt to catch, kill or attempt to kill any great white shark, or purchase, sell or offer for sale any part or product derived thereof.
No person shall, except with the authority of a permit, damage, uproot, collect or land or attempt to damage, uproot, collect or land any live or dead coral.
No person shall, except with the authority of a permit, engage in fishing, collecting or disturbing any live or empty pansy shell.
No person shall, except with the authority of a permit, engage in fishing, collecting or removing any aquatic plants, except for own use and in quantities not exceeding 10 kg aquatic plants, however, 1 kg dead shells or 50 kg shellgrit per day is permitted without a permit.
No person shall, except with the authority of a permit, damage, pick, uproot, collect or land or attempt to damage, pick, uproot, collect or land any live or dead sea fans or sea pens.
No person shall, without a permit issued by the Director-General, culture any marine organisms.
No person shall, except with the authority of a permit, catch any fish or collect any aquatic plants for commercial purposes.

For more information phone: (021) 402-3911 or consult the Amended Regulations (R24 of 14 January 2000) in terms of the Marine Living Resources Act, 1998.