Angler's File: Common carp

Common carp

Conservation status
Vulnerable (IUCN 3.1)^[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cypriniformes
Family:	Cyprinidae
Genus:	Cyprinus
Species:	C. carpio
Binomial name
Cyprinus carpio Linnaeus, 1758

The common carp (Cyprinus carpio) is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.^[2]^[3] The wild populations are considered vulnerable to extinction, but the species has also been domesticated and introduced into environments worldwide, and is often considered an invasive species.^[2] It gives its name to the carp family: Cyprinidae. It is on the List of the world's 100 worst invasive species.

Taxonomy

Cyprinus carpio carpio on the dry lake bed of Lake Albert in New South Wales, Australia

The three subspecies are:

Cyprinus carpio carpio (European carp) is found in Eastern Europe (notably the Danube and Volga Rivers).^[2]^[4]
Cyprinus carpio haematopterus (Amur carp) is native to eastern Asia.^[4]^[5]
Cyprinus carpio rubrofuscus, from Southeast Asia,^[4] is treated as a separate species Cyprinus rubrofuscus by many authorities.^[6]

It is related to the common goldfish (Carassius auratus), with which it is capable of interbreeding.^[7]^[8]

History

The common carp is native to Asia which has been introduced to every part of the world with the exception of the Middle East and the poles. The original common carp was found in the inland delta of the Danube River about 2000 years ago, and was torpedo-shaped and golden-yellow in colour. It had two pairs of barbels and a mesh-like scale pattern. Although this fish was initially kept as an exploited captive, it was later maintained in large, specially built ponds by the Romans in south-central Europe (verified by the discovery of common carp remains in excavated settlements in the Danube delta area). As aquaculture became a profitable branch of agriculture, efforts were made to farm the animals, and the culture systems soon included spawning and growing ponds.^[9] The common carp's native range also extends to the Black Sea, Caspian Sea and Aral Sea.
Both European and Asian subspecies have been domesticated.^[4] In Europe, domestication of carp as food fish was spread by monks between the 13th and 16th centuries. The wild forms of carp had reached the delta of the Rhine in the 12th century already, probably also with some human help.^[10] Variants that have arisen with domestication include the mirror carp, with large, mirror-like scales (linear mirror – scaleless except for a row of large scales that run along the lateral line; originating in Germany), the leather carp (virtually unscaled except near dorsal fin), and the fully scaled carp. Koi carp (錦鯉 (nishikigoi) in Japanese, 鯉魚 (pinyin: lĭ yú) in Chinese) is a domesticated ornamental variety that originated in the Niigata region of Japan in the 1820s.^[11] They also invaded the Great Lakes in 1896 when the area near Newmarket, Ontario, flooded and allowed them to escape into the Holland River.

Physiology

Dutch wild carp

Wild common carp are typically slimmer than domesticated forms, with body length about four times body height, red flesh, and a forward-protruding mouth. Their average growth rate by weight is about half the growth rate of domesticated carp ^[12]^[13] They do not reach the lengths and weights of domesticated carp, which (range, 3.2–4.8 times)^[2] can grow to a maximum length of 120 centimetres (47 in), a maximum weight of over 40 kilograms (88 lb),^[2] and an oldest recorded age of at least 65 years, but reliable information seems to exist about nishikigoi of over 100 years.^[13]^[14] The largest recorded carp, caught by an angler in January 2010 at Lac de curtons (Rainbow Lake) near Bordeaux, France, weighed 42.6 kilograms (94 lb).^[15] The largest recorded weight of a domesticated carp was of a nishikigoi especially bred for size, with a length of 125 cm and a weight of 45 kg.^[13]^[16]

Habitat

Carp from Vltava river, Czech Republic

Although tolerant of most conditions, common carp prefer large bodies of slow or standing water and soft, vegetative sediments. As schooling fish, they prefer to be in groups of five or more. They naturally live in temperate climates in fresh or slightly brackish water with a pH of 6.5–9.0 and salinity up to about 0.5%,^[17] and temperatures of 3 to 35°C.^[2] The ideal temperature is 23 to 30°C, with spawning beginning at 17–18°C; they easily survive winter in a frozen-over pond, as long as some free water remains below the ice.^[17] Carp are able to tolerate water with very low oxygen levels, by gulping air at the surface.^[3]

Diet

Common carp are omnivorous. They can eat a vegetarian diet of water plants, but prefer to scavenge the bottom for insects, crustaceans (including zooplankton), crawfish, and benthic worms.

Reproduction

An egg-layer, a typical adult female can lay 300,000 eggs in a single spawn.^[18] Although carp typically spawn in the spring, in response to rising water temperatures and rainfall, carp can spawn multiple times in a season. In commercial operations, spawning is often stimulated using a process called hypophysation, where lyophilized pituitary extract is injected into the fish. The pituitary extract contains gonadotropic hormones which stimulate gonad maturation and sex steroid production, ultimately promoting reproduction.

Predation

A single carp can lay over a million eggs in a year,^[3] yet their population remains the same, so the eggs and young perish in similarly vast numbers. Eggs and fry often fall victim to bacteria, fungi, and the vast array of tiny predators in the pond environment. Carp which survive to juvenile are preyed upon by other fish such as the northern pike and largemouth bass, and a number of birds (including cormorants, herons, goosanders, and ospreys)^[19] and mammals (including otter and mink).

Introduction into other habitats

Carp gather near a dock in Lake Powell

Carp in Maribyrnong River, Australia

Carp in the duck pond in Herbert Park, Dublin, Ireland

Koi in Chinese Garden Zürich, Switzerland

Common carp have been introduced, sometimes illegally, to most continents and some 59 countries. Due to their fecundity and their feeding habit of grubbing through bottom sediments for food, they are notorious for altering their environments. In feeding, they may destroy, uproot, disturb and eat submerged vegetation, causing serious damage to native duck, such as canvasbacks, and fish populations.^[20] Similar to the grass carp, the vegetation they consume is not completely digested, and rots after excretion, raising the nutritional level of the water and causing exsessive algae growth. They destroy nests of other fish and eat their eggs, reducing their numbers significantly.
Efforts to eradicate a small colony from Tasmania's Lake Crescent without using chemicals have been successful, but the long-term, expensive and intensive undertaking is an example of both the possibility and difficulty of safely removing the species once it is established.^[21] One proposal, regarded as environmentally questionable, is to control common carp by deliberate exposing them to carp-specific Koi herpes virus with its high mortality rate. In Utah Lake, the common carp's population is expected to be reduced by 75% by using nets to catch millions of them and either give them to people who will eat them or processing them into fertilizer. This, in turn, will give the native June sucker a chance to recover its declining population. Another method is by trapping them in tributaries they use to spawn with seine nets and exposing them to rotenone. This method has shown to reduce their impact within 24 hours and greatly increase the native vegetation and desirable fish species. This also leaves the baby carp easily preyed upon by native fish.
In Australia, enormous anecdotal and mounting scientific evidence indicates introduced carp are the cause of permanent turbidity and loss of submergent vegetation in the Murray-Darling river system, with severe consequences for river ecosystems, water quality and native fish species.^[22] In Victoria, Australia, common carp has been declared as noxious fish species, the quantity a fisher can take is unlimited.^[23] In South Australia, it is an offence for this species to be released back to the wild.^[24] An Australian company converts common carp into plant fertilizer.^[25]
Common carp were brought to the United States in 1831.^[26] In the late 19th century, they were distributed widely throughout the country by the government as a food-fish, but they are no longer prized as a food-fish. As in Australia, their introduction has been shown to have negative environmental consequences,^[27] and they are usually considered to be invasive species. Millions of dollars are spent annually by natural resource agencies to control common carp populations in the United States.^[22]
Common carp are believed to have been introduced into the Canadian province of British Columbia from Washington. They were first noted in the Okanagan Valley in 1912, as was their rapid growth in population. Carp are currently distributed in the lower Columbia (Arrow Lakes), lower Kootenay, Kettle (Christina Lake), and throughout the Okanagan system.^[28]

Angler's File

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Tuesday, 20 November 2012

Common carp