Common yabby
Encyclopedia
The common yabby, Cherax destructor, is an Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

n freshwater crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

 in the Parastacidae
Parastacidae
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.Three genera are to be found in Chile,...

 family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

. It is listed as a vulnerable species
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

 of crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 by the World Conservation Union
World Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...

 (IUCN), though the validity of this listing is questionable; wild yabby populations remain strong, and have expanded into new habitats created by reservoirs and farm dams.

Its common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 of "yabby
Yabby
Yabby is a name given in Australia to two different kinds of crustacean.* A freshwater yabby is a crayfish of the genus Cherax . They are often caught for food. A widespread species is the common yabby, Cherax destructor.* A marine yabby is a ghost shrimp , which lives in deep burrows in the...

" is also applied to many other Australian Cherax
Cherax
Cherax is the largest and most widespread genus of fully and partially aquatic crayfish in the Southern Hemisphere. Its members may be found in lakes, rivers and streams across most of Australia and New Guinea. In Australia the many species of Cherax are commonly known as yabbies...

species of crustacean (as well as to marine ghost shrimp of the infra-order Thalassinidea
Thalassinidea
Thalassinidea is an infraorder of decapod crustaceans that live in burrows in muddy bottoms of the world's oceans. In Australian English, the littoral thalassinidean Trypaea australiensis is referred to as the yabby , frequently used as bait for estuarine fishing; elsewhere, however, they are...

). Yabbies occasionally reach up to 30 cm (12 in) in length but are more commonly 10–20 cm (4–8 in) long.

Colour is highly variable and depends on water clarity and habitat; yabbies can range from black, blue-black or dark brown in clear waters to light brown, green-brown or beige in turbid waters. Yabbies specifically bred to be a vibrant blue colour are now popular in the aquarium trade in Australia.

Ecology

Yabbies are common throughout Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

 and New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...

, although the species also occurs in southern Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...

, South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...

 and parts of the Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...

, making it the most widespread Australian crayfish. It has been introduced to Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

, where it is an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....

 and poses a threat to other Cherax
Cherax
Cherax is the largest and most widespread genus of fully and partially aquatic crayfish in the Southern Hemisphere. Its members may be found in lakes, rivers and streams across most of Australia and New Guinea. In Australia the many species of Cherax are commonly known as yabbies...

crayfish species native to the region, such as gilgies
Cherax quinquecarinatus
Cherax quinquecarinatus is a small freshwater crayfish endemic to the south-west corner of Australia. It is one of two species known as gilgie, or jilgi, which is a seasonal food source for people of the region...

 (Cherax quinquecarinatus).

Yabbies are found in swamps, streams, rivers, reservoirs and farm dams at low to medium elevations. It appears yabbies were largely restricted to lower altitude habitats in inland areas of south-eastern Australia including the Murray-Darling Basin
Murray-Darling Basin
The Murray-Darling basin is a large geographical area in the interior of southeastern Australia, whose name is derived from its two major rivers, the Murray River and the Darling River. It drains one-seventh of the Australian land mass, and is currently by far the most significant agricultural...

 before European settlement, with the Euastacus
Euastacus
Euastacus is a genus of freshwater crayfish known as "spiny crayfish". They are found in the south-east of the Australian mainland, along with another genus of crayfish, Cherax...

spiny crayfish species found in higher altitude habitats and the coastal river systems. High altitude yabby populations in Lakes Eucumbene
Lake Eucumbene
Lake Eucumbene is a man-made lake on the Eucumbene River in the Snowy Mountains of Southern New South Wales in Australia. The lake was created by the damming of the river as part of the Snowy Mountains Scheme. The dam was built between 1956 and 1958....

 and Jindabyne
Lake Jindabyne
Lake Jindabyne is a man-made lake on the Snowy River on the eastern slopes of the Snowy Mountains in Southern New South Wales. The lake was created by the damming of the River as part of the Snowy Mountains Scheme.-Flow of water:...

, which are on the upper reaches of the coastal Snowy River
Snowy River
The Snowy River is a major river in south-eastern Australia. It originates on the slopes of Mount Kosciuszko, Australia's highest mainland peak, draining the eastern slopes of the Snowy Mountains in New South Wales, before flowing through the Snowy River National Park in Victoria and emptying into...

 system, are unusual and may be translocated.

Yabbies are found in many ephemeral waterways, and can survive dry conditions for long periods of time (at least several years) by aestivating (lying dormant) in burrows sunk deep into muddy creek and swamp beds.

Yabbies are primarily nocturnal
Nocturnal animal
Nocturnality is an animal behavior characterized by activity during the night and sleeping during the day. The common adjective is "nocturnal"....

 detritivore
Detritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...

s, feeding primarily on algae and plant remains, at night, but also opportunistically feeding on any fish or animal remains they encounter at any time of day.

In Southern Australia it is commonly accepted that yabbies are active and thereby available to catch during the warmer months. (Colloquially any month with the letter "R" in it.) When temperatures fall below 16 °C (60.8 °F), they enter a state of reduced metabolic activity, or "partial hibernation".

Yabbies are an important dietary item for Australian native freshwater fish like Murray cod
Murray Cod
The Murray cod is a large Australian predatory freshwater fish of the Maccullochella genus and the Percichthyidae family. Although the species is a called cod in the vernacular, it is not related to the northern hemisphere marine cod species...

 and golden perch
Golden perch
The golden perch, Macquaria ambigua, is an Australian native freshwater fish, primarily of the Murray-Darling river system. It is not a true perch of the genus Perca....

.

Catching

Catching yabbies, or "yabbying", in rivers and farm dams is a popular summertime activity in Australia, particularly with children. The most popular method involves tying a piece of meat to a few metres of string or fishing line, which in turn is fastened to a stick in the bank, and throwing the meat into the water. The string is pulled tight when a determined yabby grasps the meat in its claws and tries to make off with it. The line is then slowly pulled back to the bank, with the grasping yabby usually maintaining its hold on the meat. When the meat and the grasping yabby reaches the water's edge, a net is used to quickly scoop up both the meat and the grasping yabby in one movement.

Other methods of catching yabbies involve various types of nets and traps. Local fishing regulations must be checked before using any nets and traps for yabbies; many types of nets and traps are banned as wildlife such as platypus
Platypus
The platypus is a semi-aquatic mammal endemic to eastern Australia, including Tasmania. Together with the four species of echidna, it is one of the five extant species of monotremes, the only mammals that lay eggs instead of giving birth to live young...

, water rats and long-necked turtles can become trapped in them and drown.

Aquaculture

The common yabby is a popular species for aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

, although their burrowing can destroy dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

s.

Yabbies can also be found in private property dams where permission to fish must be obtained. Bag limits apply to yabbies in most states. For example in South Australia it is illegal to catch over 200 yabbies a day. All females carrying eggs under their tails must be returned to the water.

Yabbies as food

While less common than prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...

s and other crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s, yabbies are eaten in Australia much like crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 in other countries. Usually yabbies are boiled, and then eaten as is or with condiments. Yabbies are also occasionally served at restaurants, where it may be prepared in salads, ravioli
Ravioli
Ravioli are a traditional type of Italian filled pasta. They are composed of a filling sealed between two layers of thin egg pasta dough and are served either in broth or with a pasta sauce. The word ravioli is reminiscent of the Italian verb riavvolgere , though the two words are not...

, pasta
Pasta
Pasta is a staple food of traditional Italian cuisine, now of worldwide renown. It takes the form of unleavened dough, made in Italy, mostly of durum wheat , water and sometimes eggs. Pasta comes in a variety of different shapes that serve for both decoration and to act as a carrier for the...

 etc.

In New South Wales, yabbies can be seen sold live at some fish markets such as Sydney Fish Market
Sydney Fish Market
The Sydney Fish Market is a commercial enterprise in Sydney, New South Wales, Australia. Sydney Fish Market is located on Blackwattle Bay, in the Inner West suburb of Pyrmont. It is 2 kilometres west of the Sydney central business district, in the local government area of the City of Sydney...

.
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