clarkii is a freshwater crayfish species, native to the Southeastern
United States, but found also on other continents, where it is often
an invasive pest. It is known variously as the red swamp crawfish,
red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug.
and range expansion
native range of P. clarkii is along the Gulf Coast from northern
Mexico to the Florida panhandle, as well as inland, to southern
Illinois and Ohio. It has also been introduced, sometimes deliberately,
outside its natural range to countries in Asia, Africa, Europe and
elsewhere in the Americas. In northern Europe, the populations are
self maintaining but not expanding, while in southern Europe, P.
clarkii is multiplying and actively colonising new territory, at
the expense of the native crayfish, Astacus astacus and Austropotamobius
spp.. Individuals are reported to be able to cross many miles of
relatively dry ground, especially in wet seasons, although the aquarium
trade and anglers may have hastened the spread in some areas (it
is believed that anglers using P. clarkii as bait introduced it
to the American state of Washington). Attempts have also been made
to use P. clarkii as a biological control organism, to reduce levels
of the snails involved in the life cycle of schistosomiasis, leading
to the dispersal of P. clarkii in, for instance, Kenya.
clarkii is most commonly found in warm fresh water, such as slowly-flowing
rivers, marshes, reservoirs, irrigation systems and rice paddies.
It is considered to be the most ecologically plastic species in
the Order Decapoda, and is able to grow quickly even in only seasonally
present water, being able to tolerate dry spells of up to four months.
P. clarkii grows quickly, and is capable of reaching weights in
excess of 50 g, and sizes of 5.512 centimetres (2.24.7
in) long. It is also able to tolerate slightly saline water, which
is unusual for a crayfish. The average lifetime of Procambarus clarkii
is 5 years. It is known that some individuals have reached ages
(in nature) over 6 years.
burrowing activities of P. clarkii can lead to damage to water courses
and to crops, particularly rice crops, and its feeding can disrupt
native ecosystems. It may out-compete the native crayfish species,
and is a vector for the crayfish plague fungus Aphanomyces astaci,
for crayfish virus vibriosis and a number of worms parasitic on
of P. clarkii account for a large majority of the crayfish produced
in the United States and elsewhere. Crayfish farming began in Louisiana
in the 18th century, taking place in rice fields in a concurrent
or alternate culture system. The concurrent culture of rice and
crayfish makes use of land, resources, equipment, and infrastructure
already being used for rice production. However, crawfish production
has decreased in recent years due to an increase of imports from
China, which is now the world's leading producer of crawfish and
is also using a rice-based system. A number of species of crustaceans
were introduced to China to create markets for aquaculture and because
they are better adapted to growing in a rice field than native fish
species. Rice-fish farming originated in China and is once again
growing as the yields from Green Revolution practices used to grow
rice are no longer increasing and resources, such as land and water,
are becoming more limited.
clarkii has also been introduced elsewhere for cultivation, such
as Spain, where its success is attributable to its ability to colonise
disturbed habitats that would be unsuitable for the native crayfish.
P. clarkii is also marketed by biological supply companies for teaching
and research. P. clarkii also exhibits different color morphs, including
white, blue, and orange and are commonly sold in pet stores.
introduction of P. clarkii has also resulted in economic losses
in some regions. In the Baixo Mondego region of Portugal, it caused
a decrease in 6.3% of profits in rice fields. However, this was
on a wet-seeded field. All negative effects of crawfish can be avoided
if adult crawfish are separated from the seed and seedlings.
clarkii as Food
Procambarus clarkii are eaten in United States,Cambodia, Europe,
China, Africa, Australia, Canada, New Zealand and the Caribbean.
About 98% of the crayfish harvested in the United States come from
Louisiana, where the standard culinary terms are crawfish or écrevisses.
produces 90% of the crawfish in the world and consumes 70% locally.
crawfish are usually boiled in a large pot with heavy seasoning
(salt, cayenne pepper, lemon, garlic, bay leaves, etc.) and other
items such as potatoes, corn on the cob, onions, garlic, and sausage.
There are many differing methods used to season a crawfish boil
and an equal number of opinions on which one is correct. They are
generally served at a gathering known as a crawfish boil.
clarkii normally reproduces sexually, but recent research suggests
it may also reproduce by parthenogenesis.