Procambarus fallax f. virginalis | Marbled crayfish

Pre 2017

2017 - 2020


Conservation status

Least concern

Legal status

Third schedule listed species under regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011 (Note: regulation 50 not yet enacted).

Listed as a Schedule 9 species under articles 15 & 15A of the Wildlife Order (Northern Ireland) 1985 (Note: article 15A not yet enacted).

Regulated invasive species of Union concern under the European Regulation on the prevention and management of the introduction and spread of invasive alien species [1143/2014].


Invasive species - risk of High Impact

Introduction pathways - 1

Escape from Confinement

Introduction pathways subclass - 1

Pet/aquarium species

Invasive score


NAPRA Ireland risk assessed

Yes. This species underwent a Non-native species APplication based Risk Analysis in 2014.

Overall risk of this species to Ireland is categorised as: MAJOR with a VERY HIGH level of confidence.

Overall conclusion summary: This crayfish species has the potential to seriously threaten the conservation status of native White-clawed Crayfish populations in Ireland. In addition, native biodiversity and ecosystem function are also likely to be threatened if abundant populations establish in the wild in Ireland. Furthermore, this non-native crayfish species could interfere with recreational fisheries.

View the full risk assessment:

Species Biology


A crayfish that can reach 13cm in length but is more usually 10cm. Body colour ranges from tan to brown to green to blue tinged or bright blue but always overlaid with a variable marbled pattern. Claws are small and also marbled (Buglife, undated; National Biodiversity Data Centre, undated).


Unique among crayfish, this species is parthenogenetic i.e. capable of asexual reproduction (cloning). As such, a single animal is sufficient to start a population (Holdich, 2011). It can attain high numbers very quickly and therefore poses a great risk to any ecosystem it invades.

It is a voracious feeder in order to maintain its high rate of reproduction and has the potential to out-compete Ireland's native White-clawed crayfish ( Austropotamobius pallipes) (Zieritz, 2011). It is omnivorous and will consume almost anything under laboratory conditions (Holdich, 2011).

Hides under stones, rocks and logs (Chucholl, 2011) and will burrow but only under extreme conditions (Holdich, 2011). This species can breathe in air and can be kept in unaerated tanks as long as it can get to the surface to breathe (Vogt 2008 in Holdich 2011).

Potential vector of the crayfish plague (Aphanomyces astaci) (Souty-Grosset et al., 2006 in Chucholl, 2011). Its main threat is its potential to alter aquatic ecosystems and decrease biodiversity as other non-indigenous crayfish have done in Europe (Ziertiz, 2011).

May be predated by coots (Fulica atra), herons (Ardea cinerea), perch (Perca fluviatilis), pike (Esox lucius), otter (Lutra lutra), mink (Mustela vison) and eels (Anguilla anguilla) (Holdich & Black, 2007).


Reproduction is by parthenogenesis. Only females of this species have been recorded and she produces young which are genetic replicas (Holdich, 2009). Capable of high rates of reproduction. Each member of the population can produce 270 eggs every 8-9 weeks. The young achieve maturity at 25-35 weeks post hatching (Zieritz, 2011).

Pathway and vector description

Was first introduced to Germany in the 1990's via the aquarium trade. From there it was released to the wild as unwanted pets or escaped captivity (Zieritz, 2011). It is readily available for purchase on the internet (Reynolds & O'Keefe, 2009) and its release to the wild as an unwanted pet is deemed to be the most likely pathway to introduction in Ireland (Millane & Caffrey, 2014). Its speed of breeding and growth mean hobbyists often end up with surplus stock, which may then be dumped in the wild (Holdich, 2009). Once established it can disperse over land and by water. It is reported to be an excellent climber, even vertical glass walls (Vogt, 2008 cited in Holdich, 2011). There is also a small risk of introduction as a contaminant of imported fish stocks or angling gear (Millane & Caffrey, 2014).

Mechanism of impact

Competition, Predation, Disease transmission

Management approach

There is an EU wide ban on the keeping or release of this species (European Commission, 2017). There are no effective methods for control or eradication of crayfish at present (NNSS, 2011). A particular complication with this species is that there is no need for them to maintain a minimum viable population size, thus making them even harder to eradicate (Chucholl, 2011). Control may only be possible by a combination of methods (NNSS, 2011).


Cosgrove et al. (2008 as cited in Millane & Caffrey, 2014) regards trapping as 'ineffective' due to the complicated nature of the habitat.


'The use of biocides (e.g. natural pyrethroides) is an option for a pond population but these are unlikely to work in a complex river catchment, or indeed in a canal or large lake' (Millane & Caffrey, 2014).

Broad environment


Habitat description

As no indigenous populations of this species have been discovered its habitat can only be indicated from its introduced range. In Germany it inhabits only lentic habitats (Zieritz, 2011).

Species group


Native region

North America

Similar species

White-clawed crayfish (Austropotamobius pallipes). A. pallipes shows no marbled pattern and its claws are more substantial.


World distribution(GBIF)

Established in Madagascar, where its populations are rapidly expanding (Zieritz, 2011). In the EU it has been recorded in the wild in Croatia, the Czech Republic, Germany, Italy, the Netherlands, Slovakia (European Commission, 2017).

Native distribution

Native to South Georgia and Florida (Zieritz, 2011).

Temporal change

Records submitted to Data Centre in 2024

The following map is interactive. If you would prefer to view it full screen then click here.

How can you help

Report any sightings to the National Biodiversity Data Centre. Do not purchase or dispose of in the wild.



Buglife (undated) Crayfish identification, distribution and legislation. Leaflet produced for Buglife and the Environment Agency. Buglife, Plymouth Site accessed 9 October 2017.

Chucholl, C (2011) Invasive Species Compendium Datasheet report for Procambarus fallax f. virginalis (marmorkrebs). Site accessed 13 October 2017.

Cosgrove, P.J., Maguire, C.M. and Kelly, J. (2008). Non-native crayfish exclusion strategy andcontingency plan. Prepared for NIEA and NPWS as part of Invasive Species Ireland pp. 10.

European Commission. (2017). Invasive Alien Species of Union Concern. European Union, Luxembourg.

Holdich, D.M. (2009). Identifying crayfish in British waters. Crayfish Conservation in the British Isles pp. 147-164. Brickland J., Holdich D.M. and Imhoff E.M. (eds) (2009). Crayfish conservation in the British Isles. Proceedings of a conference held on 25th March 2009 in Leeds, UK. Site accessed 9 October 2017.

Holdich, D. (2011). GB Non-native Organism Risk Assessment for Procambarus sp. - Marbled crayfish Site accessed 13 October 2017.

Holdich, D.M. & Black, J (2006) The spiny-cheek crayfish, Orconectes limosus (Rafinesque, 1817) [Crustacea: Decapoda: Cambaridae], digs into the UK. Aquatic Invasions 2 (1) pp. 1-15, Site accessed 6 October 2017.

Millane, M. & Caffrey, J. (2014) Risk Assessment of Procambarus sp. – Marbled Crayfish. Prepared for Inland Fisheries Ireland and the National Biodiversity Data Centre Site accessed 13 October 2017.

National Biodiversity Data Centre (undated) Crayfish identification. Handout. Site accessed 9 October 2017.

Reynolds, J.D. & O'Keefe, C. (2009) Protect Irish Crayfish. Leaflet. National Parks and Wildlife Service. Dublin. Site accessed 6 October 2017.

Souty-Grosset C.; Holdich D.M.; Noel P.Y.; Reynolds J.D.; Haffner P., (2006). Atlas of crayfish in Europe. Paris, France: Muséum National d´Histoire Naturelle, 187 pp.

Vogt, G. (2008). The marbled crayfish: a new model organism for research on development,epigenetics and evolutionary biology. Journal of Zoology 276(1): 1-13.

Zieritz, A. (2011) Marbled crayfish, Procambarus marmorkrebs Factsheet. Non-native Species Secretariat (NNSS). Site accessed 13 October 2017.

CABI Datasheet

Additional comments

Genetically Procambarus fallax f. virginalis is the parthenogenetic form of P. fallax, which is native to South Georgia and Florida. However, a native population of the parthenogenetic form has not been identified. This means that there is 'no known native founder population of this species' (Zieritz, 2011).

This species can also be known as P. marmorkrebs.