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Cherax snowden is a species of crayfish from West Papua in Indonesia (Oinsok River Drainage, Sawiat District, Chendravasikh and Kepala Burung Peninsulas). In the wild, they live in freshwater river tributaries. It is popular as a freshwater aquarium pet across Asia, Europe, and North America because of its orange-tipped claws. Specimens were previously misidentified as members of Cherax holthuisi, also from West Papua.


Adult body length is 10 cm for males and 7 cm for females. Different shades of green (brownish-green and bluish-green) is the predominant body color throughout their lives, their claw tips are orange. The first samples became known in the West in 2006 by means of internet pet shops. By the time it was examined by professional zoologists in 2015 ( Cherax snowden, a new species of crayfish (Crustacea, Decapoda, Parastacidae) from the Kepala Burung (Vogelkop) Peninsula in Irian Jaya (West Papua), Indonesia) it was already popular as a pet Europe, East Asia and America under the name "orange tip". The scientific species description was published by German zoologists from the Institute for Environmental Sciences University Koblenz-Landau, Landau. The species was named after Edward Snowden to honor his contribution to the freedom of speech.

The Tasmanian giant freshwater crayfish (Astacopsis gouldi), also called Tasmanian giant freshwater lobster, is the largest freshwater invertebrate in the world. The species is only found in the rivers below 400 metres (1,300 ft) above sea level in northern Tasmania, an island-state of Australia. It is listed as an endangered species on the IUCN Red List due to overfishing and habitat degradation, experts estimate there are less than 100,000 in the wild.

The diet of the freshwater crayfish varies with age, but predominantly consists of decaying wood, leaves and their associated microbes. They may also eat small fish, insects, rotting animal flesh and other detritus when available. A. gouldi is very long-lived, surviving for up to 60 years, it has previously been reported to attain weights of up to 6 kilograms (13 lb) and measure over 80 centimetres (31 in) long, however in recent years the majority of larger specimens are 2–3 kilograms (4.4–6.6 lb). When fully mature the species has no natural predators due to its large size, while smaller individuals can be prey of platypus, river blackfish and rakali.

Name


Although a crayfish, it is locally known as the giant freshwater lobster. Historical accounts suggest the Aboriginal Tasmanians referred to freshwater lobsters as Tayatea. The specific epithet of Astacopsis gouldi was assigned in 1845 and honours the convict artist, William Buelow Gould, whose 1832 Sketchbook of Fishes includes the first-known representation of the species.


Sketch of a giant freshwater crayfish attributed to William Buelow Gould from Sketchbook of fishes (1832)
Biology and ecology

A. gouldi are omnivorous crustacean, primarily eating decaying wood, leaves and their associated microbes. They may also eat small fish, insects, rotting animal flesh and other detritus when available. Colour varies considerably among individuals, with adults ranging from dark brown-green to black or blue. Males can be identified by their larger pincers compared to females. Young juveniles moult several times a year, becoming less frequent as they mature. The species is long lived and known to live up to 60 years of age and attain weights of up to 6 kilograms (13 lb), however in recent years specimens of 2–3 kilograms (4.4–6.6 lb) are considered large.


Results from a genetic study indicated that specimens of A. gouldi from a site in the Pipers River catchment (north of Launceston) were significantly genetically distinct from the rest of the species.

The dispersal and migratory patterns of A. gouldi are largely unknown, but they are recorded to be most active during summer and autumn when water temperatures are higher, they are also known to walk over land. A 2004 study found the species appears to have periods of relative inactivity restricted to a "home-pool" for 1-10 days interspersed with movements involving travel over relatively large distances, including one crayfish moving over 700 m in a single night.

Juveniles are suspected to migrate to seasonal creeks or shallow faster-flowing waters known as riffle zones where they are at less risk from predators including other crayfish, fish, platypus and rakali. Larger sub-adults (<100 millimetres (3.9 in) carapace length) will move to deeper-flowing straight sections of the catchment. Adults have no natural predators and will take refuge in sheltered deep pools and appear to tolerate each other despite being aggressive elsewhere. Males are territorial and maintain a harem of up to several females.

Tasmanian giant freshwater crayfish have extremely slow maturation rates, with females reaching sexual maturity at approximately 14 years of age, a weight of 550 grams (19 oz) and a carapace length of 120 millimetres (4.7 in). Males are thought to reach maturity more quickly at around 9 years, 300 grams (11 oz) and 76 millimetres (3.0 in) carapace length. Females mate and spawn once every two years in autumn after a summer moult, producing 224–1300 eggs proportional to its size. Gestation of the eggs takes about nine months, with females carrying the eggs on their tail through winter. After hatching in mid-summer, the hatchlings of about 6 millimetres (0.24 in) attach to the female's swimming legs and will remain with the mother until a few months later in autumn. A long reproductive process means that females spend much of their life attached to their eggs and hatchlings.

Distribution and habitat


A. gouldi inhabit rivers and streams at elevations of approximately 20–300 metres (66–984 ft) above sea level with upper limits of 400 metres (1,300 ft). Approximately 18% of the waterways in which the species habitat is predicted to occur are protected in a formal reserve.

Formerly, the species was distributed from the Arthur River in the west and eastwards across northern Tasmania, where it was found in all rivers flowing into Bass Strait, except for those of the Tamar catchment. Today, distribution of A. gouldi is patchy and limited to less disturbed areas. Large declines in numbers or localised extinctions are thought to have occurred in the Welcome, Montagu, Rubicon, Don, Brid, Boobyalla, Pipers, Ringarooma, Duck, Little and Great Forester Rivers and Claytons Rivulet. The species has been introduced into the North Esk catchment (St Patricks River) and the Derwent catchment where populations have become established.


Flowerdale River, Meunna, North West Tasmania. A waterway ecosystem where Astacopsis gouldi is likely to occur
A. gouldi inhabit slow-moving rivers and streams of several sizes including headwaters and rivulets. Water should be of high quality with high dissolved oxygen content, little suspended sediment, and water temperatures between 5.2–21 °C (41.4–69.8 °F), although relatively low temperatures are preferred. Adults need still, deep pools with submerged decaying logs and overhanging, but not eroding, banks to shelter beneath. Juveniles prefer shallow, faster-flowing stream habitats with distinct cavities to hide under and higher portions of bolder substrate and moss cover.

Excellent habitat requires intact, native riparian vegetation which is densely canopied and shades the waterways. However, the species has been recorded in confines of non-native riparian vegetation (e.g. pine plantations), without riparian vegetation and in farm dams. A 1994 study failed to find crayfish in waterways of established agricultural areas where all riparian vegetation had been removed.


Threats and conservation

The principle causes for the population declines of the Tasmanian giant freshwater crayfish has been previous overfishing, continued illegal fishing and habitat disturbance by agricultural, forestry and urban activities. Population surveys and behavioural research are being undertaken in order to be able to provide improved habitat management and protection. Land clearing typically requires approval with a Forest Practices Plan and 10m streamside buffers. Until recently, buffer zones only prohibited machinery operating near waterways with harvesting and burning permitted up to the stream edge. A. gouldi is protected under the federal government Environment Protection and Biodiversity Conservation Act 1999 and Tasmanian state government Threatened Species Protection Act 1995 which prohibit the fishing or handling of the species without permit. The effectiveness of some current conversation efforts are not fully determined and are subject to review in the 2016 Recovery Plan.

The relative ease of catch, slow maturation, infrequent breeding (once every 2 years) and the removal of young when females are caught make A. gouldi highly susceptible to human fishing pressures. The larger individuals were targeted for eating and trophies, which has had a significant effect on breeding stock, completely removing populations from some river systems. The lack of any bag limit until the 1990’s allowed overfishing to occur for many years.

In 1998, the species was listed as "vulnerable" under Australian law and an amendment to the Inland Fisheries Act 1995 made it illegal to catch or handle A. gouldi without a permit, carrying a maximum fine of A$10,000. Although past fishing pressures are believed to have had a significant impact on populations, a degree of illegal fishing is known to continue and has potential to significantly threaten the remaining populations. The level of illegal fishing is not fully known, but is evidenced by prosecutions, the presence of bait lines and anecdotal reports. New developments of roads and forestry tracks can consequentially allow illegal fishers to access previously unexploited populations.

Habitat disturbance for A. gouldi includes the removal or destruction of native riparian vegetation, bank erosion, removal of snags, stream flow alterations such as culverts and farm dams, siltation and toxic chemical runoffs.

The clearance of riparian vegetation causes the destabilisation of waterway banks which impacts the burrowing habitats for A. gouldi and increases sediment runoff into waterways. Increased sediment levels arising from agricultural and forestry related land-uses have been correlated with decreased abundances of freshwater crayfish. The increase in turbidity impacts the ability of the crayfish to effectively transpire oxygen through its gills. Sediment depositions arising from upstream forestry operations have been observed to impact in-stream habitat for considerable distances downstream of up to 10km. Loss of riparian canopy cover allows more light to reach the water and has a negative impact on habitat by increasing water temperatures.

While Tasmanian river basins have been found to be generally less impacted by flow alterations than other catchments across Australia, some river basins (such as the Mersey and Pipers–Ringarooma river basins) are heavily impacted by hydro-electric schemes, the use of in-stream barriers reduce the dispersal potential of the crayfish. Water extraction for irrigated agriculture and urban water use is of concern to a lesser degree, however there has been an identified lack of contingency plans in the event of reduced environmental flows in waterways. Anecdotal reports indicate that low environmental flows caused the death of giant freshwater crayfish in several catchments in the north-west and north-east of Tasmania in 2006–2007


In 1994, a large spill from a holding dam at a pyrethrum extraction plant caused a major kill in the Hogarth Rivulet and the main channel of the Great Forester River. Reports from locals and fisheries officers suggested that there was little life left in much of the main channel, and the incident is believed to have severely harmed any populations that were in the waterways at the time of the spill.

The 2016 Tasmanian floods, which killed 3 people, raised concerns about the future for the Tasmanian giant freshwater crayfish after up to 100 carcasses were found washed up along the banks of the Leven River on a property in North West Tasmania, likely caused by the high water flows during the flood. Previous population surveys in the area had revealed already low numbers. There are further concerns that the floods displaced snags from waterways which are a vital part of the habitat for the species.

The 2006-2010 Giant Freshwater Lobster Recovery Plan highlighted several catchments (or parts of) which had been identified to contain good habitat quality and good crayfish populations and should be considered for conservation efforts. Some areas require renewed evaluation since habitat quality may have changed since surveys were conducted. North-eastern Tasmanian rivers lacked sufficient data to fully determine all areas of importance.

Aitken Creek, downstream of Nook Road to Sheffield Road crossing
Black River and tributaries
Dip Range streams
Duck River catchment above Trowutta Road
Emu River tributaries
Flowerdale River from the top of the catchment to near Lapoinya
Great Forester River and tributaries
Inglis River and tributaries
Little Forester River and tributaries
Cam River catchment
Hebe River (catchment of Flowerdale River)
Arthur River catchments including Frankland, Rapid, Keith and Lyons rivers
^ a b c d e
^ a b
^ "Threatened species and ecological communities publications - Biodiversity". Australian Government – Department of the Environment and Heritage. Retrieved 11 October 2011.
^
^ "Factsheet". Inland Fisheries Service. Retrieved 1 September 2004.
^ Lois Koehnken (2001). North-east rivers environmental review: a review of Tasmanian environmental quality data to 2001 (PDF). Darwin, NT: Environment Australia. ISBN 0-642-24374-3. Supervising Scientist Report 168.
^ Wirsu, Piia (7 August 2016). "Crayfish recovery plan more important than ever after population disaster". The Advocate. Fairfax Regional Media. Retrieved 10 August 2016.
^ Gibson, Sallese (4 August 2016). "Fears for Tasmanian giant freshwater lobsters after carcasses found following major flooding". ABC News. Australian Broadcasting Corporation. Retrieved 10 August 2016.
^


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The signal crayfish, Pacifastacus leniusculus, is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the Scandinavian Astacus astacus fisheries, which were being damaged by crayfish plague, but the imports turned out to be a carrier of that disease. The signal crayfish is now considered an invasive species across Europe and Japan, ousting native species there.

Description and ecology


A white oval patch at the joint of the fingers of the claw distinguishes this species.
Members of this species are typically 6–9 centimetres (2.4–3.5 in) long, although sizes up to 16–18 cm (6.3–7.1 in) are possible. They are bluish-brown to reddish-brown in colour with robust, large, smooth claws. They have a white to pale blue-green patch near the claw hinge, like the white flags that signalmen used for directing trains—hence the name.

The life cycle of the signal crayfish is typical for the family Astacidae. Around 200–400 eggs are laid after mating in the autumn, and are carried under the female's tail until they are ready to hatch the following spring. The eggs hatch into juveniles, which pass through three moults before leaving their mother. Sexual maturity is reached after two to three years, and the life span can be up to 20 years.

The signal crayfish is an omnivore, with most of its dietary intake being detritus.


Native range

The signal crayfish is native to North America west of the Rocky Mountains, including the Canadian province of British Columbia, and the U.S. states of Washington, Oregon, and Idaho. It was introduced to California in 1912 into the San Lorenzo River watershed and from there rapidly spread throughout the state. The only native crayfish remaining in California is the Shasta crayfish (Pacifastacus fortis), where efforts are being made to create a barrier to Signal crayfish invasion. Within North America, it has also been introduced to Nevada, and the populations in Utah may be the results of introductions. It has also been found in Alaska, specifically Kodiak Island, in the Buskin River and BuskinLake. It is listed as a species of Least Concern on the IUCN Red List.

Introduction into Europe


A signal crayfish in Spain
From 1907, crayfish plague, an infectious disease caused by the water mould Aphanomyces astaci, damaged stocks of the native European crayfish Astacus astacus. Since the signal crayfish occupied a similar ecological niche in its native range, it was imported in the 1960s to Sweden and Finland to allow recreational and commercial crayfish capture. It was not realised at the time that the signal crayfish was a carrier of the crayfish plague. All American species carry the infection, but it is only lethal to individuals that are already stressed; to European species, the infection is rapidly fatal.


The signal crayfish is now the most widespread alien crayfish in Europe, occurring in 25 countries, from Finland to Great Britain and from Spain to Greece. It was first introduced to Great Britain in 1976, and is now widespread across the British mainland as far north as the Moray Firth. It has also been observed on the Isle of Man, but not in Ireland.

In both Sweden and Finland (where crayfish are eaten) the catch of signal crayfish exceeds that of the noble crayfish. The signal crayfish is sold at roughly half the price compared to the noble

crayfish.



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Parastacidae is the family of freshwater crayfish found in the southern hemisphere. The family is a classic Gondwana-distributed taxon, with extant members in South America, Madagascar, Australia, New Zealand and New Guinea, and extinct taxa also in Antarctica.

Distribution


The natural range of the family Parastacidae
Three genera are found in Chile, Virilastacus, Samastacus and Parastacus, the last of which also occurs disjunctly in southern Brazil and Uruguay.


There are no crayfish native to continental Africa, but seven species on Madagascar, all of the genus Astacoides.

Australasia is particularly rich in crayfish. The small genus Paranephrops is endemic to New Zealand. Two genera, Astacopsis and Parastacoides are endemic to Tasmania, while a further two are found on either side of the Bass Strait – Geocharax and Engaeus. The greatest diversity, however, is found on the Australian mainland. Three genera are endemic and have restricted distributions (Engaewa, Gramastacus and Tenuibranchiurus), while two are more widespread and contain more than one hundred species between them: Euastacus, around the Australian coast from Melbourne to Brisbane, and Cherax across Australia and New Guinea.

Fossil record

The oldest specimens from the family Parastacidae are the Albian fossils of Palaeoechinastacus from Victoria, Australia. The only northern hemisphere representative is also a fossil, Aenigmastacus crandalli from Canada.



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Hobbseus is a genus of crayfish in the family Cambaridae. It comprises seven species, six of which are endemic to Mississippi; H. prominens is the only species to range outside Mississippi, being also found in Alabama. Three of the seven species are listed as endangered (EN) on the IUCN Red List, while three are of uncertain status (DD) and one is of least concern (LC).


Hobbseus attenuatus Black, 1969 – DD
Hobbseus cristatus (Hobbs, 1955) – DD
Hobbseus orconectoides Fitzpatrick & Payne, 1968 – EN
Hobbseus petilus Fitzpatrick, 1977 – DD
Hobbseus prominens (Hobbs, 1966) – LC
Hobbseus valleculus (Fitzpatrick, 1967) – EN
Hobbseus valobushensis Fitzpatrick & Busack, 1989 – EN
^ "Hobbseus Fitzpatrick and Payne, 1968". Integrated Taxonomic Information System. Retrieved March 4, 2011.
^ Susan B. Adams (2008), "Hobbseus prominens" (PDF), Crayfishes of Mississippi website, 1.0, Oxford, Mississippi: United States Forest Service
^ James W. Fetzner, Jr. (January 14, 2008). "Genus Hobbseus Fitzpatrick and Payne, 1968". Crayfish Taxon Browser. Carnegie Museum of Natural History.
^ S. Adams, J. Cordeiro & C. A. Taylor (2010). "Hobbseus attenuatus". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. Retrieved March 4, 2011.
^ S. Adams (2010). "Hobbseus cristatus". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. Retrieved March 4, 2011.
^ S. Adams, J. Cordeiro & C. A. Taylor (2010). "Hobbseus orconectoides". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. Retrieved March 4, 2011.
^ S. Adams (2010). "Hobbseus petilus". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. Retrieved March 4, 2011.
^ S. Adams (2010). "Hobbseus prominens". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. Retrieved March 4, 2011.
^ S. Adams, J. Cordeiro & C. A. Taylor (2010). "Hobbseus valleculus". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. Retrieved March 4, 2011.
^ S. Adams (2010). "Hobbseus valobushensis". IUCN Red List of Threatened Species. Version 3.1. International Union for Conservation of Nature. Retrieved March 4, 2011.


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Astacus pachypus, the Caspian crayfish is a species of crayfish found in the Caspian Sea, the Don river, and parts of the Black Sea and Sea of Azov, where it lives in salinities of up to 14‰. It is listed as Data Deficient in the IUCN Red List.



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