Common Yabby, Yabbie

The length of C. destructor often ranges between 10 to 20 cm but occasionally will grow to 30 cm (CAB International 2017). In Australia, the average common yabby caught by amateur anglers usually weighed between 20 g to 80 g. Females will experience a reduced growth rate after maturity is reached likely in response to the energy requirements of spawning; for this reason, females are often smaller than males, who can grow up to 300 g (NSW Department of Primary Industries 2017).

They have two spawning events per season and produce approximately 1000 eggs per spawn. Reproduction is linked to water temperature, so the spring and summer would be ideal seasons (Witnall 2000). The diet of C. destructor is not fully know, but it is known to be an omnivorous species that feeds on plants, detritus, and some arthopods (CAB International 2017). Their diet also switches according to climate. During summer seasons, they tend to eat fish, and in the winter, they eat plants and detritus (Beatty 2005). Cherax destructor may have cannibalistic tendencies in areas where there is an overabundance of the species and low levels of natural food sources (CAB International 2017). Yabby have shown antagonistic behavior to get access to limited resources. In a trial competition between Yabby and the marron, Cherax tenuimanus, Yabby won. They concluded that its aggression led to success (Drake 2007).

Potential pathway(s) of introduction: Unauthorized intentional release

Yabby is not currently in waters connecting to the Great Lakes and is not known to be transported through the Great Lakes region. However, it has been increasingly transported globally which could increase the future risk of introduction into the Great Lakes. Cherax destructor was originally transported for aquaculture and food, but more recently, it has gained popularity as a pet (Chucholl 2013). Cherax destructor has a relatively high commercial value (Chucholl 2013). When used as bait, unused live bait is often directly discarded in to water (Drake 2007). The potential for specimens to be released and become established is extremely high, especially in temperate and warmer climates (CAB International 2013).

Cherax destructor has a Moderate probability of establishment if introduced to the Great Lakes (Confidence level: High).

Cherax destructor is known to have a high tolerance to a variety of environments. They have been found in regions with climates similar to the Great Lakes. Yabby prefer muddy waters opposed to clear water environments (Withnall 2000), and they survive dry periods by burrowing in the mud (Geddes and Smallridge 1993). The extreme temperatures near the Great Lakes may affect the growth of Yabby during some seasons, but their high proliferation would help them survive. They have two spawning events per season and produce approximately 1000 eggs per spawn. Reproduction is linked to water temperature, so the spring and summer would be ideal seasons (Witnall 2000). Their diet switches based on climate and would likely find adequate food in the Great Lakes.

The Great Lakes provide an abundant habitat that is suitable for the survival, development, and reproduction of this species. Yabby’s ideal habitat consists of high oxygen levels and vegetation; they are most likely to be found in swamps, streams, rivers, and dams (Withnall 2000). Predators for Yabby are aquatic birds, such as cormorants, herons, and ibis, and all three of these are found in the Great Lakes region.

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

Environmental	Socioeconomic

There is little or no evidence to support that Cherax destructor has the potential for significant socio-economic impacts if introduced to the Great Lakes.

It has not been reported that Cherax destructor poses a threat to human health or water quality. There is no evidence that this species negatively impacts infrastructure, economic sectors, recreational activities and associated tourism, or the aesthetic appeal of the areas it inhabits.

Cherax destructor has the potential for moderate beneficial impact if introduced to the Great Lakes.

Cherax destructor has commercial value but its economic contribution is small. It is sometimes employed recreationally, but adds little value to local communities or tourism.

Ontario’s Invasive Species Act prohibits the transportation, introduction (into Ontario), possession, release, propagation, purchase, sale, or trade of C. destructor (Invasive Species Act 2015). Pennsylvania prohibits people from transporting, introducing or importing any fish, bait fish or fish bait including crayfish (PA State Laws, Title 30). It is unlawful to possess, import or sell C. destructor in Ohio (OAC Chapter 1501:31-19). It is illegal to possess, import, sell, or offer to sell C. destructor in Michigan (NREPA Part 413). Illinois lists C. destructor as an injurious species as defined by 50 CFR 16.11-15. Therefore C. destructor cannot be “possessed, propagated, bought, sold, bartered or offered to be bought, sold, bartered, transported, traded, transferred or loaned to any other person or institution unless a permit is first obtained from the Department of Natural Resources (17 ILL. ADM. CODE, Chapter 1, Sec. 805).” This law also states that any interstate transporter is prohibited from transferring “any injurious species from one container to another; nor can they exchange or discharge from a container containing injurious species without first obtaining written permission from the Department (17 ILL. ADM. CODE, Chapter 1, Sec. 805).” The law also prohibits the release of any injurious species, including C. destructor. Wisconsin prohibits the transportation, possession, transfer of, or introduction of all nonnative crayfish (Wisconsin Chapter NR 40). Minnesota lists C. destructor as prohibited meaning that a person may not possess, import, purchase, sell, propagate, transport, or introduce C. destructor (Minnesota Rule 6216.0250). There are no regulations on C. destructor in New York or Indiana.

Control

Biological

If C. destructor were to become established in the Great Lakes basin, populations might be controlled by predatory fish. Eels, Burbot, perch, pike, and Smallmouth bass are some well-known predators of crayfish that exist in the Great Lakes (Westman 1991 in Gherardi et al. 2011). One study observed in a mesocosm experiment that Northern pike (Esox Lucius) were an efficient predator of crayfish independent of prey size (Neveu 2001 in Gherardi et al. 2011), which could be significant considering the large size of C. destructor. Fish predation could be effective in managing C. destructor, but some studies have suggested that stocking predacious fish could actually increase non-indigenous crayfish species population densities (Gowing and Momot 1979, and Holdich and Domaniewski 1995 in Gherardi et al. 2011). Predatory aquatic birds, such as cormorants, herons, and ibis are predators of C. destructor and all exist in the Great Lakes region (Farrell and Leonard 2001).

The use of microbial agents to control crayfish populations has been reviewed in previous studies (Gherardi et al. 2011; Scalici et al. 2009). C. destructor is known to be susceptible to the crayfish plague, Aphanomyces astaci (Scalici et al. 2009), of which North American species are much more resistant (Persson et al. 1987; Unestam 1975). Four populations of C. destructor in Spain were eradicated by introducing signal crayfish (Pacifastacus leniusculus)  infected with the plague into the populations (J. Dieguez-Uribeondo, pers. comm. in Souty-Grosset et al., 2006 via Scalici et al. 2009). C. destructor is also susceptible to the microsporidian disease, Thelohania parastaci (Moodie, Le Jambre, and Katz 2003) and the Cherax destructor systemic parvo-like virus (CdSPV) (Edgerton 1996, Edgerton et al. 1997 in Diggles 2011). Gherardi et al. (2011) mentions that the use of genetically modified strains of A. astaci has been hypothesized as a potential way to control invasive crayfish in Europe, but there is a significant risk that using a genetically modified strain in conjunction with the existing wild-type could affect more than just the target species. The use of microbial agents as a method of control for C. destructor in the Great Lakes basin would also warrant the consideration of indirect effects on native crayfish populations.

Aside from predatory fish and disease, other potential methods of control would be the use of sex pheromones or the release of sterile males. Aquiloni and Gherardi (2010) observed the capability of sex pheromones as a method of control in another species of crayfish, which could have implications for the control of C. destructor if it becomes established in the Great Lakes. Additionally, the release of sterile male C. destructor into a population could be an effective method of control if the species were to become established within the Great Lakes basin. The sterile male release technique is species-specific and has been tested for other species of invasive crayfish in laboratory settings (Aquiloni et al. 2009). 

Chemical

The use of chemical agents to control C. destructor populations has been examined by Gherardi et al. (2011) and the New South Wales Department of Primary Industries (2017). In particular, the assessments of insecticides as a possible control of crayfish populations could provide insight on the viability of this control method for C. destructor. C. destructor is susceptible to organochlorines found in some insecticides and herbicides (NSW Department of Primary Industries 2017). Gherardi et al. (2011) noted the success of insecticides derived from natural pyrethrum and synthetic pyrethroids in eradicating crayfish populations in Europe (Gherardi et al. 2011). Organophosphate insecticides (e.g. fenthion and methyl parathion) have also been utilized in attempts to eradicate invasive crayfish species, but these organophosphates apparently lack specificity among crustaceans and insects (Gherardi et al. 2011), so using this control method may harm native species as well as C. destructor. Other studies have observed the effect surfactants have on controlling crayfish activity, but this method has shown to have a limited effect in the eradication of populations (Cabral et al. 1997 and Fonseca et al. 1997 via Gherardi et al. 2011). Salt can be used as a chemical control in confined settings; C. destructor will die at a salinity of 25 ppt or above (NSW Department of Primary Industries 2017).

Physical

The use of physical barriers and diversions have been reviewed as a method to control non-indigenous crayfish species populations in Europe and America (Gherardi et al. 2011; Kerby et al. 2005). Kerby et al. (2005) observed that red swamp crayfish (Procambarus clarkii) movement was significantly reduced by natural barriers. Other physical control methods include the use of electric fences and vibrations (Gherardi et al. 2011). Mechanical removal of C. destructor could also be a potential control method. Continuous trapping has been demonstrated to work on rusty crayfish (Orconectes rusticus) in a Northern Wisconsin lake (Hein et al. 2007) as well as in aquaculture ponds (Bills and Marking 1988). Gherardi et al. (2011) suggests that electrofishing and trapping could also be an effective way of controlling non-indigenous crayfish species populations.

Note: Check state and local regulations for the most up-to-date information regarding permits for pesticide/herbicide/piscicide/insecticide use.