Orconectes limosus

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 (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

Introduction pathways - 2

Release in Nature

Introduction pathways subclass - 2

Fishing in the wild

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 of the native White-clawed Crayfish populations in Ireland. . In addition, native biodiversity and ecosystem function are likely to be threatened if abundant populations establish in the wild in Ireland. Furthermore, this non-native crayfish species could interfere with bank stability, and reduce the value of commercial and recreational fisheries.

 View the full risk assessment:

Species Biology


Freshwater crayfish with distinctive spiny cheeks, reaching up to 11cm long (Aldridge, 2006). Usually coloured dark brown to olive green (may appear from living in anoxic sediments) with reddish stripes across the abdominal segements. Light yellow colour under the body (Holdich & Black, 2007, Holdich & Sibley, 2009). The underside of the claws have orange tips with a black band below (Buglife, undated). 


Ideal habitat conditions for this species are calm turbid waters but they will tolerate fast flowing waters (NNSS, 2011). Cold, polluted and euthrophic waters are within the physiological tolerances of this invasive species giving it a broad range of habitats in which it can thrive (Aldridge, 2006). In dry spells, when water levels drop, Orconectes limosus digs a burrow and waits for conditions to become more favourable (Holdich & Black, 2007).

Their burrowing activities can destabilize river/lake banks leading to erosion (Aldridge, 2006) and reducing water quality (NNSS, 2011). A combination of high fecundity and rapid growth means large populations can develop rapidly (Holdich & Sibley, 2009) and this omnivore may outcompete the native white-clawed crayfish (Austropotamobius pallipes) for resources. They are known carriers of Crayfish plague (Aphanomyces astaci) (Holdich & Sibley, 2009) which can decimate native crayfish populations. Their sheer numbers may interfere with fish spawning sites (NNSS, 2011).

They 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; Reynolds & O'Keefe, undated). 




The females produce >300 eggs in spring (Holdich & Black, 2006). They are carried for 1-3 weeks and hatch into independent juvenile crayfish in May or June (Aldridge, 2016). Reach sexual maturity early at 18 months of age (NNSS, 2011) and can live for 4 years (Aldridge, 2016). 

Pathway and vector description

Originally introduced to Europe to supplement the dwindling native crayfish (Astracus astracus) stocks due to Crayfish plague (Aphanomyces astaci). Once established they readily disperse along waterways, across land, sometimes by predators (Aldridge, 2016). The nearest population to Ireland is in the UK where they may have been introduced as unwanted pets, as bait or as a food source for fish by anglers or (Holdich & Black, 2006; NNSS, 2011; Aldridge, 2016) or as a contaminant with commercial fish stocks (Holdich & Black, 2006; Millane & Caffrey, 2014). 

Mechanism of impact

Competition, Disease transmission

Management approach

There are no effective methods for control or eradication of crayfish at present (NNSS, 2011).


Currently trapping is most used but juveniles don't often enter the traps and the adults are very wary making them difficult to trap (Holdich & Black, 2006).


Biocides can be used but they are expensive and cannot be used in flowing water (NNSS, 2011).

Broad environment


Habitat description

Freshwater rivers, lakes, canals, ponds, waterfilled gravel pits and substantial streams. They have a preference for turbid calm conditions. (NNSS, 2011). 

Species group


Native region

North America

Similar species

Austropotamobius papilles (White-clawed crayfish). A. papilles is brown to olive coloured, sometimes blueish and the underside of the claws are whiteish (National Biodiversity Data Centre, undated). 


World distribution(GBIF)

Has been introduced to 19 EU member states – Austria, Belgium, Bulgaria, Croatia, the Czech Republic, France, Germany, Hungary, Italy, Latvia, Lithuania, Luxembourg, the Netherlands, Poland, Romania, Slovakia, Slovenia, Spain and the United Kingdom (European Commission, 2017). 

Native distribution

East coast of the U.S.A.

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. 



Aldridge, D (2016) Spinycheek crayfish, Orconectes limosus. Factsheet. Non-native Species Secretariat (NNSS). Site accessed 6 October 2017.

Alekhnovich, A., Buric, M. (2017): NOBANIS – Invasive Alien Species Fact Sheet – Orconectes limosus. – From : Online Database of the European Network on Invasive Alien Species – NOBANIS Site accessed 6 October 2017.

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

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

European Environment Agency (EEA) (2012). The impacts of invasive alien species in Europe. Technical report No 16/2012. EEA, Copenhagen. 114 p. Site accessed 6 October 2017.

Hobbs, HH (1948) On the cray-fishes of the limosus section of the genus Orconectes (Decapoda, Astacidae) Journal of the Washington Academy of Sciences. 38 Site accessed 6 October 2017.

Holdich, D & 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. 

Holdich D.M. & Sibley P.J. (2009) ICS and NICS in Britain in the 2000s; 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.

Millane, M. & Caffrey, J. (2014) Risk Assessment of Orconectes limosus (Rafinesque 1817) – Spiny-cheek Crayfish. Prepared for Inland Fisheries Ireland and the National Biodiversity Data Centre.

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

Non-native Species Secretariat (NNSS) (2011) Rick assessment for Orconectes limosus – Spiny-cheek crayfish. Risk assessment carried out for Great Britain. Site accessed 6 October 2017.

Pavlovic, S; Miloševic, S; Borkovic, S; Simic, V; Paunovic, M; Žikic, R & Saicic, Z (2006) A Report of Orconectes (Faxonius) limosus (Rafinesque, 1817) [Crustacea: Decapoda: Astacidea: Cambaridae: Orconectes: Subgenus Faxonius] in the Serbian Part of the River Danube, Biotechnology & Biotechnological Equipment, 20 (1) pp. 53-56, DOI:10.1080/13102818.2006.10817304. Site accessed 6 October 2017. 

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

Inland Fisheries Ireland

UK Crayfish Hub