Seafood of the Week - Crayfish

Northern kōura, Paranephrops planifrons

Crayfish – also called crawfish, crawdads, freshwater lobsters, or mudbugs – are freshwater crustaceans resembling small lobsters, to which they are related; taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills and are found in bodies of water that do not freeze to the bottom. They are mostly found in brooks and streams where there is fresh water running, and which have shelter against predators. Most crayfish cannot tolerate polluted water, although some species such as the invasive Procambarus clarkii are hardier. Crayfish feed on living and dead animals and plants.





The name "crayfish" comes from the Old French word escrevisse (Modern French écrevisse). The word has been modified to "crayfish" by association with "fish" (folk etymology). The largely American variant "crawfish" is similarly derived.
Some kinds of crayfish are known locally as lobsters, crawdads, mudbugs, and yabbies. In the Eastern United States, "crayfish" is more common in the north, while "crawdad" is heard more in central and southwestern regions, and "crawfish" further south, although there are considerable overlaps.
The study of crayfish is called astacology.





In Australia, New Zealand and South Africa, the term crayfish or cray generally refers to a saltwater spiny lobster, of the genus Jasus that is indigenous to much of southern Oceania, while the freshwater species are usually called yabby or kōura, from the indigenous Australian and Māori names for the animal respectively, or by other names specific to each species. An exception is the freshwater Murray crayfish, which belongs to the family Parastacidae and is found on Australia's Murray River.
In Singapore, the term crayfish typically refers to Thenus orientalis, a seawater crustacean from the slipper lobster family. True crayfish are not native to Singapore, but are commonly found as pets, or as an invasive species (Cherax quadricarinatus) in the many water catchment areas, and are alternatively known as freshwater lobsters.





The body of a decapod crustacean, such as a crab, lobster, or prawn, is made up of twenty body segments grouped into two main body parts, the cephalothorax and the abdomen. Each segment may possess one pair of appendages, although in various groups these may be reduced or missing. On average, crayfish grow to 6.9 in. (17.5 centimeters) in in length, but some grow larger.

Astacidae: Austropotamobius pallipes

There are three families of crayfish, two in the Northern Hemisphere and one in the Southern Hemisphere. The Southern-Hemisphere (Gondwana-distributed) family Parastacidae lives in South America, Madagascar and Australasia, and is distinguished by the lack of the first pair of pleopods. Of the other two families, members of the Astacidae live in western Eurasia and western North America and members of the family Cambaridae live in eastern Asia and eastern North America.
Madagascar has an endemic genus, Astacoides, containing seven species.
Europe is home to seven species of crayfish in the genera Astacus and Austropotamobius.
Cambaroides is native to Japan and eastern mainland Asia.





The greatest diversity of crayfish species is found in southeastern North America, with over 330 species in nine genera, all in the family Cambaridae. A further genus of astacid crayfish is found in the Pacific Northwest and the headwaters of some rivers east of the Continental Divide. Many crayfish are also found in lowland areas where the water is abundant in calcium, and oxygen rises from underground springs.
Crayfish were introduced purposely into a few Arizona reservoirs and other bodies of water decades ago, primarily as a food source for sport fish. They have since dispersed beyond those original sites.





Australasia has over 100 species in a dozen genera. Many of the better-known Australian crayfish are of the genus Cherax, and include the marron (now believed to be two species, Cherax tenuimanus and C. cainii), red-claw crayfish (Cherax quadricarinatus), common yabby (Cherax destructor) and western yabby (Cherax preissii). The marron are some of the largest crayfish in the world. They grow up to several pounds in size. C. tenuimanus is critically endangered, while other large Australasian crayfish are threatened or endangered.
Australia is home to the world's two largest freshwater crayfish – the Tasmanian giant freshwater crayfish Astacopsis gouldi, which can achieve a mass of up to 11 lb (5 kilograms)  and is found in the rivers of northern Tasmania, and the Murray crayfish Euastacus armatus, which can reach 4.4 LB (2 kilograms) and is found in much of the southern Murray-Darling basin.
The two species of Paranephrops are endemic to New Zealand, where they are known by the Māori name kōura.

Crawfish Boil

Crayfish are eaten worldwide. Like other edible crustaceans, only a small portion of the body of a crayfish is edible. In most prepared dishes, such as soups, bisques and étouffées, only the tail portion is served. At crawfish boils or other meals where the entire body of the crayfish is presented, other portions, such as the claw meat, may be eaten. Like all crustaceans, crayfish are not kosher because they are aquatic animals that do not have both fins and scales. They are therefore not eaten by observant Jews.
As of 2005, Louisiana supplies 95% of the crayfish harvested in the US. In 1987, Louisiana produced 90% of the crayfish harvested in the world, 70% of which were consumed locally. In 2007, the Louisiana crawfish harvest was about 54,800 tons, almost all of it from aquaculture. About 70%–80% of crayfish produced in Louisiana are Procambarus clarkii (red swamp crawfish), with the remaining 20%–30% being Procambarus zonangulus (white river crawfish).





Crayfish are commonly sold and used as bait, either live or with only the tail meat, and are good at attracting channel catfish, largemouth bass, pike and muskellunge. Sometimes the claws are removed so that the crayfish don't stop fish from biting the hook. Crayfish easily fall off the hook, so casting should be slow.
The result of using crayfish as bait has led to various ecological problems at times. According to a report prepared by Illinois State University, on the Fox River and Des Plaines River watershed, "The rusty crayfish (used as bait) has been dumped into the water and its survivors outcompete the native clearwater crayfish". This situation has been repeated elsewhere, as the crayfish bait eliminates native species.
The use of crayfish as bait has been cited as one of the ways zebra mussels have spread to different waterways, as members of this invasive species are known to attach themselves to crayfish.