Distribution Of Crayfish Research Articles

English

Abstract Due to the increasing anthropogenic pressures and the introduction of invasive alien species, indigenous crayfish species are rarely found in the urban areas of big cities. The aim of this research was to study, for the first time, presence and distribution of freshwater crayfish in artificial lakes of the Maksimir Park, located in the centre of Zagreb, the capital of Croatia. Additionally, the goal was to estimate population size and structure, and analyse morphometric characteristics, the proportion of injuries and crayfish body condition. In 4 out of 5 lakes within the park, two crayfish species, Astacus astacus and Astacus leptodactylus, were recorded with no overlap in their distribution. Each species was established in two lakes in relatively abundant populations. Differences in body condition, sex ratio and proportion of injuries were recorded between species. Recorded differences are most likely the result of different trapping techniques applied, predation of alien invasive species of turtles and intraspecific competition. Obtained results will serve as a baseline for further research and monitoring of the crayfish fauna in the Maksimir lakes.

The Signal CrayfishPacifastacus leniusculus— Distribution and Invasion in the Southern Baltic Coastal River

The signal crayfish Pacifastacus leniusculus (Dana, 1852) of North American origin was introduced to Europe (to Scandinavia) in the 1960s. Since that time due to translocation to many countries, biological features and ecological plasticity, it became widespread, invasive and displaced native species. The paper reports first multi- point colonization of P. leniusculus in the Polish rivers. The aim of the study was to determine the current distribution of the signal crayfish in the coastal Baltic tributary (the River Wieprza) after 20 years of deliberate releases in its drainage area. During sampling at 28 sites with use of the “Pirate” crayfish traps and hand collection methods in spring and summer 2014, 127 P. leniusculus individuals were found at 8 sites in the Wieprza and its two tributaries, both away from and close to known sites of their introduction in 1995 and 1996 in the Wieprza River drainage area. The species spreads via the Wieprza River towards the Baltic brackish waters. With such expansion of this species, it is expected to be found in Polish coastal waters of the Baltic Sea and in other coastal rivers in the near future. The conflict between legal aspects of the signal crayfish farming, colonization by the species of the natural aquatic ecosystems and the expectations of consumers is discussed.

First records of the non-indigenous signal crayfish (Pacifastacus leniusculus) and its threat to noble crayfish (Astacus astacus) populations in Estonia

This study gives an overview of status and distribution of signal crayfish (Pacifastacus leniusculus), the first NICS in Estonia and its influence on native noble crayfish (Astacus astacus) populations. The first specimen of signal crayfish was caught during the monitoring of noble crayfish in North Estonia in 2008. The signal crayfish has since been found in three additional sites. Test fishing has indicated that the abundance of signal crayfish has been fluctuating between years and among localities. It has had strong negative impact on abundance of one noble crayfish population. The disconnected distribution of signal crayfish strongly suggests that these populations are the result of human-assisted introductions. Real-time PCR analyses proved that signal crayfish carry the causative agent of the crayfish plague, an oomycete Aphanomyces astaci, thus contributing to its spread. Mortalities in noble crayfish populations had been caused by A. astaci strains from A, B and E genotype group.

Monitoring of noble, signal and narrow-clawed crayfish using environmental DNA from freshwater samples

For several hundred years freshwater crayfish (Crustacea—Decapoda—Astacidea) have played an important ecological, cultural and culinary role in Scandinavia. However, many native populations of noble crayfish Astacus astacus have faced major declines during the last century, largely resulting from human assisted expansion of non-indigenous signal crayfish Pacifastacus leniusculus that carry and transmit the crayfish plague pathogen. In Denmark, also the non-indigenous narrow-clawed crayfish Astacus leptodactylus has expanded due to anthropogenic activities. Knowledge about crayfish distribution and early detection of non-indigenous and invasive species are crucial elements in successful conservation of indigenous crayfish. The use of environmental DNA (eDNA) extracted from water samples is a promising new tool for early and non-invasive detection of species in aquatic environments. In the present study, we have developed and tested quantitative PCR (qPCR) assays for species-specific detection and quantification of the three above mentioned crayfish species on the basis of mitochondrial cytochrome oxidase 1 (mtDNA-CO1), including separate assays for two clades of A. leptodactylus. The limit of detection (LOD) was experimentally established as 5 copies/PCR with two different approaches, and the limit of quantification (LOQ) were determined to 5 and 10 copies/PCR, respectively, depending on chosen approach. The assays detected crayfish in natural freshwater ecosystems with known populations of all three species, and show promising potentials for future monitoring of A. astacus, P. leniusculus and A. leptodactylus. However, the assays need further validation with data 1) comparing traditional and eDNA based estimates of abundance, and 2) representing a broader geographical range for the involved crayfish species.

Using eDNA to detect the distribution and density of invasive crayfish in the Honghe-Hani rice terrace World Heritage site.

The Honghe-Hani landscape in China is a UNESCO World Natural Heritage site due to the beauty of its thousands of rice terraces, but these structures are in danger from the invasive crayfish Procambarus clarkii. Crayfish dig nest holes, which collapse terrace walls and destroy rice production. Under the current control strategy, farmers self-report crayfish and are issued pesticide, but this strategy is not expected to eradicate the crayfish nor to prevent their spread since farmers are not able to detect small numbers of crayfish. Thus, we tested whether environmental DNA (eDNA) from paddy-water samples could provide a sensitive detection method. In an aquarium experiment, Real-time Quantitative polymerase chain reaction (qPCR) successfully detected crayfish, even at a simulated density of one crayfish per average-sized paddy (with one false negative). In a field test, we tested eDNA and bottle traps against direct counts of crayfish. eDNA successfully detected crayfish in all 25 paddies where crayfish were observed and in none of the 7 paddies where crayfish were absent. Bottle-trapping was successful in only 68% of the crayfish-present paddies. eDNA concentrations also correlated positively with crayfish counts. In sum, these results suggest that single samples of eDNA are able to detect small crayfish populations, but not perfectly. Thus, we conclude that a program of repeated eDNA sampling is now feasible and likely reliable for measuring crayfish geographic range and for detecting new invasion fronts in the Honghe Hani landscape, which would inform regional control efforts and help to prevent the further spread of this invasive crayfish.

Distribution and establishment of the alien Australian redclaw crayfish, Cherax quadricarinatus, in South Africa and Swaziland.

BackgroundThe Australian redclaw crayfish (Cherax quadricarinatus, von Martens), is native to Australasia, but has been widely translocated around the world due to aquaculture and aquarium trade. Mostly as a result of escape from aquaculture facilities, this species has established extralimital populations in Australia and alien populations in Europe, Asia, Central America and Africa. In South Africa, C. quadricarinatus was first sampled from the wild in 2002 in the Komati River, following its escape from an aquaculture facility in Swaziland, but data on the current status of its populations are not available.MethodsTo establish a better understanding of its distribution, rate of spread and population status, we surveyed a total of 46 sites in various river systems in South Africa and Swaziland. Surveys were performed between September 2015 and August 2016 and involved visual observations and the use of collapsible crayfish traps.ResultsCherax quadricarinatus is now present in the Komati, Lomati, Mbuluzi, Mlawula and Usutu rivers, and it was also detected in several off-channel irrigation impoundments. Where present, it was generally abundant, with populations having multiple size cohorts and containing ovigerous females. In the Komati River, it has spread more than 112 km downstream of the initial introduction point and 33 km upstream of a tributary, resulting in a mean spread rate of 8 km year−1 downstream and 4.7 km year−1 upstream. In Swaziland, estimated downstream spread rate might reach 14.6 km year−1. Individuals were generally larger and heavier closer to the introduction site, which might be linked to juvenile dispersal.DiscussionThese findings demonstrate that C. quadricarinatus is established in South Africa and Swaziland and that the species has spread, not only within the river where it was first introduced, but also between rivers. Considering the strong impacts that alien crayfish usually have on invaded ecosystems, assessments of its potential impacts on native freshwater biota and an evaluation of possible control measures are, therefore, urgent requirements.

First record of the invasive Australian redclaw crayfish <i>Cherax quadricarinatus</i> (von Martens, 1868) in the Crocodile River, Kruger National Park, South Africa

The redclaw crayfish Cherax quadricarinatus (von Martens, 1868), a robust freshwater crayfish native to Australia and Papua New Guinea, has now been recorded from the Kruger National Park (KNP). Previously absent from the Crocodile River, SAN Parks received a report in February 2016 of redclaw crayfish below the Van Graan Dam on the border of the KNP. Here, we provide evidence of the presence of redclaw crayfish in the Crocodile River. A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the KNP and the Komati Catchment. The negative impacts of global crayfish introductions justify efforts to discourage further introductions and prevent their secondary spread.Conservation implications: A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the Kruger National Park and the Komati Catchment.

The prevalence of Aphanomyces astaci in invasive signal crayfish from the UK and implications for native crayfish conservation.

The crayfish plague agent, Aphanomyces astaci, has spread throughout Europe, causing a significant decline in native European crayfish. The introduction and dissemination of this pathogen is attributed to the spread of invasive North American crayfish, which can act as carriers for A. astaci. As native European crayfish often succumb to infection with A. astaci, determining the prevalence of this pathogen in non-native crayfish is vital to prioritize native crayfish populations for managed translocation. In the current study, 23 populations of invasive signal crayfish (Pacifastacus leniusculus) from the UK were tested for A. astaci presence using quantitative PCR. Altogether, 13 out of 23 (56·5%) populations were found to be infected, and pathogen prevalence within infected sites varied from 3 to 80%. Microsatellite pathogen genotyping revealed that at least one UK signal crayfish population was infected with the A. astaci genotype group B, known to include virulent strains. Based on recent crayfish distribution records and the average rate of signal crayfish population dispersal, we identified one native white-clawed crayfish (Austropotamobius pallipes) population predicted to come into contact with infected signal crayfish within 5 years. This population should be considered as a priority for translocation.

Freshwater crayfish distribution update and maps for Greece: combining literature and citizen-science data

Crayfish are charismatic creatures of high interest to humans, among others playing key roles in freshwater ecosystems. Considering the significance of indigenous crayfish species (ICS) as well as the risks posed by non-indigenous crayfish species (NICS) that may dissemite a crayfish plague pathogen Aphanomyces astaci , astacological research has advanced particularly in Europe. In this context, crayfish distribution patterns are of fundamental importance. Focused on all crayfish established in the Greek wild, we provide an updated distribution and maps, combining extensive review of existing literature as well as newly emerging sources, largely represented by increasingly important citizen-science data. Obtained results demonstrate that ICS, mainly the Astacus astacus and Austropotamobius torrentium , remain relatively well settled in the country. The last ICS, Astacus leptodactylus , was translocated in few places outside its native range, leading to the formation of new flourishing populations and at least in one case it sustains commercial exploitation. Concerning NICS, a single population of Pacifastacus leniusculus is also established in the artificial lake Agra (Region of Central Macedonia) and keeps spreading. Unfortunately, there are only few methods under a very narrow range of conditions making successful eradication of unwanted NICS populations feasible. This option is even more difficult as this population is commercially exploited and traded. Since further potentially problematic NICS are also pet-traded in the country, educating public and communicating highlighted issues are the most effective ways limiting their releases and consecutive establishment in the wild.

Filling the blank spot: first report on the freshwater crayfish distribution in Albania

The knowledge on the distribution of native and non-native crayfish species in Europe has substantially advanced during last two decades. However, data on the exact distribution of European crayfish are still lacking in some regions of the Balkan Peninsula, e.g. , in Albania. Out of five European crayfish taxa, Astacus astacus and Austropotamobius torrentium are considered to occur in Albanian freshwaters. However, until now the only confirmed localities of the occurrence of any crayfish species in Albania are a single place in the Mat River drainage and Prespa Lake. Five crayfish individuals have been collected recently from two localities in Albania: Ohrid Lake and upper Devolli River (Seman basin), as a result of a repeated sampling in all main Albanian river drainages. All specimens were morphologically and molecularly identified as the noble crayfish, A. astacus , providing confirmation of its presence in this Balkan country. The present paper summarizes historic and current distribution records of the crayfishes in Albania and neighbouring countries as well as provides insight into genetic variability of Albanian A. astacus .

Distribution of crayfish species in Hungarian waters

Three native crayfish species, i.e. Astacus astacus, Astacus leptodactylus and Austropotamobius torrentium, occur in Hungary. Lately, however, non-indigenous crustaceans have also invaded the country Their most recent distribution and impact on the occurrences of the native species is not clear. Consequently, the first object of the present study was to investigate the present-day distribution and habitat preference of the native and invasive crayfish and crab species in Hungary according to water types and surface water velocity values. The second aim was to investigate the changes in the distribution patterns of all species over the last 20 years and to identify potential risks for native species in Hungary. Although A. astacus was discovered on several new locations the overall distribution of the species is decreasing. The rarest crayfish is A. torrentium which was found only at three locations, making this the most endangered crayfish in Hungary. Although A leptodactylus used to occur especially in the main branches of the Danube and Tisza Rivers it shifted towards its tributaries after O. limosus appeared here. Despite their overlapping habitat preference and the fact that O. limosus is a carrier of the lethal crayfish plague, both species still co-occur at a few locations in Hungary Pacifastacus leniusculus is invading the country from the West and although it is not present in large numbers yet, it has replaced the local A. astacus populations and may further impact its distribution when it further increases its range in the future. Although occurrences of the Chinese mitten crab (Eriocheir sinensis) the marbled crayfish (Procambarus fallax f. virginalis) and the red swamp crayfish (Procambarus clarkii) have been reported in the literature, these species were not encountered during the survey Thus indicating that their occurrence in Hungary is not widespread yet. The increasing distribution of the invaders forms a constant threat to native crayfish populations in Hungary To ensure the survival of the native species it is important to keep track of the ongoing changes in crayfish distributions. Nevertheless, additional protection measures will be required to safe-guard the survival of the native crayfish populations in Hungary.

Environmental factors influencing the distribution and abundance of the introduced signal crayfish in the north of Iberian Peninsula

The identification of habitat requirements of invasive species is essential to evaluate their spread and to assess the vulnerability of recipient ecosystems. We studied the distribution and abundance of the invasive signal crayfish (Pacifastacus leniusculus) in 43 sites in northern Spain and analysed the relationships with several abiotic and biotic parameters of the aquatic ecosystems. Our results indicated that the abundance of signal crayfish was positively associated with vegetation cover and negatively associated with boulders. Also, its abundance was positively correlated with water temperature, organic matter, cations (e.g. sodium), anions (e.g. sulfates) and abundance of some native fish species (Parachondrostoma miegii and Luciobarbus graellsii). We concluded that the habitat of signal crayfish is among salmonid stretches (headwaters) with cold waters and low proportion of organic debris, and among cyprinid stretches (low waters) with warmer waters which it inhabits with another invasive crayfish, the red swamp crayfish (Procambarus clarkii). Our analysis indicated that the presence of signal crayfish is limited in the uppermost stretches by lower water temperatures and a lower proportion of organic debris. The existence of a natural environmental limiting factor in upstream reaches facilitates the conservation of aquatic ecosystems and native fauna.

Crayfish diversity and distribution of tomlinson run state park, hancock county, West Virginia.

In 2015, a survey of epigean crayfish of Tomlinson Run State Park was conducted. The park is located in Hancock County in West Virginia’s northern panhandle. A preliminary habitat survey was conducted to map all reaches of intermittent and perennial streams as well as other crayfish habitats. Following the survey for habitat, 30 stations, each 100m long, were randomly selected using ArcGIS for both intermittent and perennial streams. Sites were sampled by performing ten seine hauls in best available habitat throughout the reach and scored using an Ohio EPA QHEI form to obtain qualitative habitat data. In order to minimize impacts within the park, all crayfish were identified to species upon capture and released following sampling at each station. In total, 471 crayfish were collected during the survey out of which four species were identified: Cambarus carinirostris, Cambarus monogalensis, Cambarus robustus, and Orconectes obscurus. No statistically significant relations between QHEI score vs. CPUE (catch per unit effort) were shown, but O. obscurus demonstrated a slightly positive correlation with increased score while C. carinirostris demonstrated a slightly negative correlation to increased score. Cambarus monogalensis was collected from three large forested seeps. Only C. carinirostris were collected from intermittent stations with overall CPUE of 0.12 crayfish per haul. CPUE scores for perennial stations indicated 1.43 crayfish per haul, but when split by species, C. carinirostris had lower CPUE (0.39) compared to O. obscurus (0.95). C. robustus had the lowest CPUE (0.09) and was the rarest species encountered in Tomlinson Run State Park.

Range expansion of the invasive rusty crayfish Orconectes rusticus (Girard, 1852) (Decapoda: Astacoidea) in northeastern Iowa (USA) rivers

The rusty crayfish Orconectes rusticus (Girard, 1852) is an invasive species that has been introduced to the Upper Midwest, USA from the Ohio River Valley, and is associated with ecological damage to aquatic systems. We examined the distributions of rusty and native crayfishes in two Iowa river systems. One hundred sites were surveyed in the upper Cedar and middle Wapsipinicon river drainages from 2013 to 2014. Four native crayfish species were collected, and contrary to a study conducted in 2002, the rusty crayfish was documented in the mainstream of both systems. Analysis of sampling methods indicates that crayfish capture rates were significantly higher in cylindrical minnow traps than in flat crayfish traps. Genetic analyses confirmed field identifications and support a single introduction of the rusty crayfish in northeastern Iowa. The pervasive distribution and life history characteristics of the rusty crayfish suggest that eradication is currently not feasible. Further monitoring is warranted in order to determine its distribution throughout Iowa’s river systems.

English

Abstract As part of a study of aquatic faunal community changes along riverine-lacustrine transition zones upstream of Lewis Smith Reservoir in northwest Alabama, USA, we collected crayfish from 60 sites in the Sipsey Fork, Brushy Creek, and selected tributaries (Black Warrior River system). After finding two unexpected and possibly-introduced crayfish species, we expanded our investigation of crayfish distributions to include crayfish obtained from stomachs of black bass (Micropterus spp.) caught at seven sites in the reservoir. To explore what crayfish species were in the drainage historically, we examined museum databases as well as stomach and intestinal contents of a variety of preserved fishes that were caught in the Sipsey Fork and Brushy Creek drainages upstream of the reservoir in the early 1990’s. Of the seven crayfish species collected, one, Orconectes (Procericambarus) sp. nr ronaldi, was not previously reported from Alabama, and another, O. lancifer, was not reported from the Black Warrior River system prior to the study. Three are known or possibly introduced species. Upstream of the reservoir, the native species Cambarus obstipus, C. striatus, and O. validus were common. The same three species were found in fish collected in the 1990’s. Orconectes perfectus was found only in the reservoir but may be native to the drainage. Orconectes lancifer was in the reservoir and in stream reaches influenced by the reservoir. Evidence points to O. lancifer being introduced in the drainage, but this is uncertain. Orconectes sp. nr ronaldi was found in a relatively small portion of Brushy Creek and its tributaries, in both flowing and impounded habitats, and may be introduced. Orconectes virilis is introduced in Alabama and was found only in stomachs of fish collected in the reservoir.

Over-invasion in a freshwater ecosystem: newly introduced virile crayfish (Orconectes virilis) outcompete established invasive signal crayfish (Pacifastacus leniusculus)

Biological invasions are a key threat to freshwater biodiversity, and identifying determinants of invasion success is a global conservation priority. The establishment of introduced species is predicted to be hindered by pre-existing, functionally similar invasive species. Over a five-year period we, however, find that in the River Lee (UK), recently introduced non-native virile crayfish (Orconectes virilis) increased in range and abundance, despite the presence of established alien signal crayfish (Pacifastacus leniusculus). In regions of sympatry, virile crayfish had a detrimental effect on signal crayfish abundance but not vice versa. Competition experiments revealed that virile crayfish were more aggressive than signal crayfish and outcompeted them for shelter. Together, these results provide early evidence for the potential over-invasion of signal crayfish by competitively dominant virile crayfish. Based on our results and the limited distribution of virile crayfish in Europe, we recommend that efforts to contain them within the Lee catchment be implemented immediately.

What do metabolic rates tell us about thermal niches? Mechanisms driving crayfish distributions along an altitudinal gradient.

Humans are rapidly altering thermal landscapes, so a central challenge to organismal ecologists is to better understand the thermal niches of ectotherms. However, there is much disagreement over how we should go about this. Some ecologists assume that a statistical model of abundance as a function of habitat temperature provides a sufficient approximation of the thermal niche, but ecophysiologists have shown that the relationship between fitness and temperature can be complicated, and have stressed the need to elucidate the causal mechanisms underlying the response of species to thermal change. Towards this end, we studied the distribution of two crayfishes, Euastacus woiwuru and Euastacus armatus, along an altitudinal gradient, and for both species conducted experiments to determine the temperature-dependence of: (1) aerobic scope (the difference between maximum and basal metabolic rate; purported to be a proxy of the thermal niche); and (2) burst locomotor performance (primarily fuelled using anaerobic pathways). E. woiwuru occupied cooler habitats than E. armatus, but we found no difference in aerobic scope between these species. In contrast, locomotor performance curves differed significantly and strongly between species, with peak locomotor performances of E. woiwuru and E. armatus occurring at ~10 and ~18 °C, respectively. Crayfish from different thermal landscapes may have similar aerobic thermal performance curves but different anaerobic thermal performance curves. Our results support a growing body of literature implying different components of ectotherm fitness have different thermal performance curves, and further challenge our understanding of the ecology and evolution of thermal niches.

Optimizing sampling effort to detect rusty crayfish (Orconectes rusticus) in southern Ontario rivers

The distribution and status of native and non-native crayfish are monitored across hundreds of lakes in Ontario (Canada). However, a corresponding effort has not been undertaken in flowing waters. Reliable and efficient sampling methods are essential for the detection of new aquatic invaders and tracking the spread of existing invasive species. In this study, a recent dataset for the invasive rusty crayfish (Orconectes rusticus) was used to determine whether the detection probability associated with intensive sampling by hand-capture (20 minutes) of 10 transects could be achieved with fewer transects. Results indicate that sampling more than three transects does not improve rusty crayfish detection. Monitoring designs based on three transects would reduce search effort by 140 minutes at each site; permitting greater spatial coverage or more frequent sampling.

Water chemistry and endangered white-clawed Crayfish: a literature review and field study of water chemistry association inAustropotamobius pallipes

Populations of the endangered white-clawed crayfish (Austropotamobius pallipes) have rapidly declined in distribution and density in recent decades as a result of invasive crayfish, disease and habitat degradation. The species is thought to be particularly sensitive to water chemistry, and has been proposed as a bio-indicator of water quality. Here we detail the results of a systematic review of the literature regarding the chemistry of waterbodies inhabited by white-clawed crayfish, along with a wide-scale field study of the chemistry of crayfish-inhabited waterbodies in the UK. We use these data to examine potentially significant variables influencing crayfish distribution. Several variables appear to have thresholds that affect crayfish distribution; crayfish presence was associated with high dissolved oxygen, low conductivity, ammonium, sodium, and phosphate, and to a lesser extent low sulphate, nitrate, and total suspended solids. Some variables (magnesium, potassium, sodium, sulphate, nitrate, and total suspended solids) may be tolerated at moderate to high concentrations in isolation (indicated by the presence of some populations in high levels of these variables), but suites of chemical conditions may act synergistically in situ and must be considered together. Recent efforts to conserve white-clawed crayfish have included relocations to Ark Sites; novel protected habitats with reduced risk of the introduction of disease, invasive crayfish and habitat degradation. We use our findings to propose the first detailed guidelines for common water chemistry variables of potential Ark Sites for the conservation of the species throughout its European range.

Marmorkrebs (Procambarus fallaxf.virginalis) are the most popular crayfish in the North American pet trade

Key-words: Marbled crayfish, pet trade, Marmorkrebs, Cambarellus Introductions of non-native crayfish around the world are increasingly tied to the distribution, sale, and eventual release of pet crayfish. As part of risk assessment for the introduction of non-native crayfish in North Amer- ica, I monitored the sale of crayfish on an auction website that special- izes in aquatic pets and aquarium supplies for a year. Three species accounted for the majority of sales: the parthenogenetic crayfish, Mar- morkrebs (Procambarus fallax f. virginalis), the Cajun dwarf crayfish (Cam- barellus shufeldtii), and the orange morph of the endangered Mexican dwarf crayfish (Cambarellus patzcuarensis). Almost half of individual cray- fish sold (48.5%) were Marmorkrebs, which is more than twice as many as C. shufeldtii, the second most commonly sold species. The Louisiana red swamp crayfish (Procambarus clarkii) was often offered for auction, but was bought much less often than the other three species. About 11% of P. clarkii auctions were successful, while more than 45% of auctions were successful for the other three. Four Cherax species were the only crayfish sold online whose native range was outside North America. Neither Mar- morkrebs nor the orange morph of C. patzcuarensis can be collected regu- larly from natural habitats in North America, suggesting that most crayfish sold online in North America are obtained from existing stocks in the pet trade, rather than being collected from natural habitats.