Procambarus fallax f. virginalis, marmorkrebs

Closely related crayfishes can often be differentiated by differences in male gonopods. Because P. virginalis is a parthenogenic species consisting only of females, P. virginalis and P. fallax can be differentiated from P. alleni (Everglades Crayfish) by examination of the annulus ventralis where the female receives sperm. Procambarus alleni typically also lack the dark stripe on the side and have dark spots near the base of the antennae (Lyko 2017, Martin et al. 2010).

In its native range, Procambarus fallax is a habitat generalist, occurring in both flowing (lotic) and still (lentic) waters ranging from ditches to lakes and rivers where it is strongly associated with vegetation (Hobbs 1942). Although they do not typically construct burrows like some other crayfishes do, P. fallax will construct simple burrows down to near the water table to pass dry seasons (Hobbs Jr. 1942). They will “explore” during wet weather (Hobbs Jr. 1942). They can live in water with very low dissolved oxygen, and with pH below 5 (Hobbs 1942). They can live in the roots of floating plants such as water lettuce and water hyacinth (Hobbs 1942).

Procambarus fallax is a host to the bacteria Acinetobacter sobria, Citrobacter freundii, Grimontia hollisae, Pasteurella multocida, and Rickettsia-like organisms; the fungus Aphanomyces astaci (also known as crayfish plague); the Mesomycetozoea Psorospermium spp.; the branchiobdellid annelids Cambarincola floridanus, C. goodnighti, and C. manni; the ostracod Uncinocythere equicurva; unidentified mites (Arachnida); and unidentified coccidian and ciliate protists (Longshaw, in Longshaw and Stebbing 2016).

In Europe, P. virginalis can reach sexual maturity at between 14-22 mm carapace length (Hamr 2023).

Potential pathways of introduction: Unauthorized intentional release, Dispersal, Hitchhiking/Fouling

The primary pathway for P. virginalis introductions is the intentional release of aquarium specimens (Souty-Grosset et al. 2006; Chucholl and Pfeiffer 2010). Its striking coloration, undemanding nature, and unique reproductive behavior makes this species especially appealing to aquarium hobbyists. However, its parthenogenic traits mean that P. virginalis can quickly overpopulate an aquarium. To prevent overcrowding, aquarium hobbyists may try to offload excess stock to other hobbyists -- or to the wild (Souty-Grosset et al., 2006). The fact that P. virginalis propagates by parthenogenesis makes the risk of release resulting in a reproducing population considerably greater than for sexually reproducing crayfish species. While regulations exist in the region that restrict the possession and sale of marbled crayfish, the conviction of a woman in Ohio for selling this species suggests introductions from the pet trade remain a concern (Milman 2022).

Procambarus virginalis is a popular model organism, with utility in neuroscience research. This species may be in government or university research labs, where introduced species prevention protocols may not be as stringent (Westhoff and Kobermann 2016). This suggests the potential for introduction via biological supply trade or lab escape.

The persistence of a Procambarus virginalis population in Burlington, Ontario (Hamr 2023) increases the risk of introduction via dispersal and hitchhiking. Procambarus virginalis are able to travel long distances over land (Guo et al. 2019; Vogt et al. 2019) and there are documented instances of active dispersal in Europe (Chucholl et al. 2012); this suggests a potential for further dispersal from the stormwater ponds in Ontario. Additionally, given the close proximity of the Ontario population, the potential exists for waterbird-mediated dispersal, bait bucket transfer, and other forms of hitchhiking introductions (Jones et al. 2009; Anastácio et al. 2014; Vogt 2021).

Procambarus virginalis has a moderate probability of establishment if introduced to the Great Lakes (Confidence level: High)

In recent years, the spread of P. virginalis has been prolific and new populations have been identified in Europe and Canada over the last several years, new records exist for Belgium (Scheers et al. 2021), Romania (Parvulescu et al. 2017), Israel (Carneiro et al. 2023), and Ontario (Hamr 2023). P. virginalis has a broad physiological tolerance and demonstrated the ability to survive a range of salinities, temperature, nutrient, and oxygen levels (Veselý et al. 2017; Vogt et al. 2019; Wisniewski et al. 2020). Climate suitability analysis suggests that P. virginalis has a high climate match with the Great Lakes (USFWS 2023) and its persistence in Burlington, Ontario indicates it can tolerate the abiotic conditions present in the Great Lakes region (Hamr 2023). Predators present in the Great Lakes, such as the round goby Neogobius melanostomus, have the potential to regulate wild populations of P. virginalis but are not expected to prevent establishment (Franta et al. 2021). Ample regulations exist in the Great Lakes region to prevent the establishment and spread of P. virginalis, however documented instances of people selling and distributing marbled crayfish despite current regulations suggest there regulations may be insufficient to prevent establishment (Milman 2022). The high fecundity and parthenogenic reproduction of P. virginalis means a single individual can establish a new population without the need for a mate (Chucholl 2010).

Summary of species impacts derived from literature review. Click on an icon to find out more...

Environmental	Socioeconomic	Beneficial

As a crayfish of North American origin, Procambarus virginalis is a carrier of Aphanomyces astaci, the crayfish plague, is speculated to transmit the chytrid fungus Batrachochytrium dendrobatidis, and a carrier of rickettsiosis and coccidiosis (Souty-Grosset et al. 2006; Francesconi et al. 2021; Maciaszek et al. 2022). This species’ fast growth rate and r-selected life history traits may allow it to outcompete native species (Jones et al. 2009; Chucholl and Pfeiffer 2010). P. virginalis can occupy multiple trophic levels and be a prey item for top level predators, it has the potential to significantly modify the food web of invaded systems (Vogt 2021). Classified as a tertiary burrower, P. virginalis may impact water quality, hydrology, and facilitate bank erosion, similar to the impacts observed for the closely related red swamp crayfish P. clarkii (Rodríguez et al. 2005; Souty-Grosset et al. 2006; Kouba et al. 2016).

Procambarus virginalis has the potential for moderate socio-economic impact if introduced to the Great Lakes.

The marbled crayfish is a tertiary burrower, and have been reported to damage irrigation systems and dams (Souty-Grosset et al. 2006), particularly in rice paddies, where they may also feed on and injure young plants (Jones et al. 2009; Kawai et al. 2009; Heimer 2010): similar effects may be possible in wild rice paddies around the Great Lakes. Fishermen in Madagascar also report severe negative impacts on their fishing grounds in the presence of marbled crayfish, but currently all evidence is anecdotal (Jones et al. 2009; Heimer 2010).

Procambarus virginalis has the potential for high beneficial impact if introduced to the Great Lakes.

The marbled crayfish remains a popular pet species in Europe and North America (Chucholl 2010; Faulkes 2010), and is also used as fishing bait. The marbled crayfish is a useful laboratory model organism for developmental physiology, epigenetics, and toxicology. Its large numbers of genetically identical offspring, rapid reproductive rate, and simple care requirements make it an ideal species for lab research (Vogt 2008; 2010). Recent publications document its increasing use as model organism and for cancer research (Jirikowski et al. 2010; Rubach et al. 2011; Hossain et al. 2018).

• Illinois: This species is not on the Illinois Aquatic Life Approved Species List and if it is not otherwise native to Illinois it is illegal to be imported or possessed alive without a permi (515 ILCS 5/20-90).
• Michigan: It is prohibited in Michigan and is unlawful to possess, introduce, import, sell or offer this species for sale as a live organism, except under certain circumstances (Natural Resources Environmental Protection Act).
• Minnesota: The transportation of live native and invasive crayfish from one waterbody to another within the state is prohibited, except by permit issued by the DNR. Live crayfish or crayfish eggs may not be imported without a permit issued by the DNR. Live crayfish may not be sold for live bait. Live crayfish can only be sold for aquarium use if the species cannot survive in Minnesota if released. Live crayfish taken from a waterbody can only be used as bait in that same waterbody (Statute 84D.07).
• Ohio: In Ohio, it shall be unlawful for any person to possess, import or sell live individuals of this species (Ohio Administrative Code 1501:31-19-01).
• Pennsylvania: It is unlawful to sell, purchase, offer for sale, barter, possess, introduce, or import all species of live crayfish in Pennsylvania except when used: as bait on, in, or about the water from which taken; for testing and scientific purposes; for restaurant consumption when adequate measures have been taken to prevent their escape and they are accompanied by documentation stating the point of origin and the destination to which they are to be delivered (58 Pa. Code § 63.46, 58 Pa. Code § 71.6).
• Wisconsin: All species of the family Cambaridae are prohibited in Wisconsin and one cannot transport, possess, transfer, or introduce it without a permit (Chapter NR 40, Wis. Adm. Code).
• Ontario: It is prohibited in Ontario, making it illegal to import, possess, deposit, release, transport, breed/grow, buy, sell, lease or trade this species (Invasive Species Act, 2015).

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control

Biological

No specific data exists on Procambarus virginalis control, but native predatory fish may be worth considering. Smallmouth bass (Micropterus dolomieu) and rock bass (Ambloplites rupestris) are known crayfish predators and good candidates to control unwanted crayfish populations. Fish predation has been shown to be effective in combination with other control methods like intensive trapping (Hein et al. 2007; Aquiloni et al. 2010).

Physical

Procambarus fallax is known to be susceptible to drought (Dorn and Trexler 2007). Provided that P. virginalis shares this characteristic, draining habitats for longer periods might reduce confined populations. Physical removal of crayfish through trapping or electrofishing can be effective, research suggests that artificial refuge traps can be a valuable tool in crayfish control (Curti et al. 2021). A triple drawdown trapping method can also support crayfish control, but is not recommended for juvenile dominated populations (Chadwick et al. 2020).

Chemical

The application of biocides such as pyrethroid insecticides at the very early stages of invasions or in confined habitats may result in complete eradication (Sandodden and Johnsen 2010). Cypermethrin and deltamethrin are lethal to Procambarus virginalis at low concentrations and do not persist in aquatic environments long-term, suggesting these are suitable biocides for the eradication of crayfish populations (Lidova et al. 2019). At a larger scale, however, the use of biocides is both expensive and ineffective because of adverse impacts on non-target organisms (Anastacio et al. 1995) and the tendency of crayfish to escape lethal doses by retreating into burrows or by climbing out of the water. Research is ongoing for chemical crayfish control, carbon dioxide treatments have been found to be a possible behavioral stimulant to enhance capture of the red swamp crayfish Procambarus clarkii (Smerud et al. 2022).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

The current status of the species in Ontario, Canada is unknown, but eradication efforts are ongoing (J. Brinsmead, Canadian Ministry of Natural Resource and Forestry, personal communication, 27 February, 2023; Hamr 2023). Species identification was morphological, and all animals found were female. Presence of the species was also confirmed with eDNA.