Carp (Cyprinus carpio)
Order: Cypriniformes Family: Cyprinidae
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Fotos: Jussi Pennanen |
Description: The carp is a relatively large, thick-bodied cyprinid. It has a broad-based dorsal fin with a serrated anterior ray and 17−22 branched fin rays. The two pairs of barbels on the upper jaw distinguish it from species of the genus Carassius, which has two representatives in Finland (crucian carp and gibel carp). The pharyngeal bones are quite firm and the teeth blunt and robust. Cultured European stocks of carp show variability in their scaly cover, some individuals having an incomplete cover but others having a compact cover, thus resembling the wild ancestor form.
Origin and distribution: The carp probably originates somewhere between Asia Minor and the Caspian Sea, from where it is thought to have spread eastwards and westwards. In China, pond-culture of carp started about 2000 years ago. In Europe, carp culture began during the Middle Ages, when wild carp from the middle reaches of the Danube were moved into ponds. The carp has now been introduced world-wide and is currently one of the most important fish species in aquaculture. Central European carp were introduced into Finland from Sweden in the 1950s, followed by carp of mixed Russian origin in the 1960s. So far, there is no established carp population in Finnish waters, all stocks being dependent on releases. When stocked as two-year-olds or older, carp have survived as far north as the Kajaani region. However, releases are concentrated in the southernmost part of the country. Releases in the shallow estuaries and bays of the Gulf of Finland have also been reasonably successful.
Reproduction: The female matures at about 2 kg, the male at a somewhat lower weight. Spawning is a short event near the shoreline, among sedges or other vegetation at a water temperature of 19−21 ºC. The eggs are adhesive and stick to plants. In aquaculture, brood fishes are allowed to spawn spontaneously in ponds or are stripped to provide eggs and milt for artificial fertilization and incubation in jars. Larvae hatch after three or four days when 5−6 mm long. In Finland, the carp has been dependent on rearing because of the long winter. Young-of-the-year carp have to be removed from ponds in autumn so that they can overwinter under conditions warmer than those prevailing in nature.
Diet, growth and migrations: Carp larvae feed first on rotifers and cladocera. Juveniles and adults feed mainly on bottom fauna such as larvae of chironomids and trichopterans, also on gastropods and small mussels. Feeding is most intense in mid and late summer, but stops in autumn when the water temperature falls to 8−10 ºC. In Finland, carp fast for a minimum of six months before the next summer.
Carp grow rapidly, and one-summer-old juveniles reared in ponds may weigh as much as 50−120 g. In cool summers, however, they may weigh less than 10 g. Under favourable natural conditions, carp may attain a weight of 1−2 kg during their fourth summer. They can live to an age of 20−30 years and reach, even in Finland, weights of 17−21 kg and lengths of 90−105 cm. They barely migrate, but may move from their release site towards a more suitable environment.
Fishing and catches: Carp angling is very popular in many European countries and is now becoming more popular in Finland, too. Catch-and-release angling is widely practised. The profitability of many carp releases has been minimal due to the lack of specialized fishing, and most carp are caught in gillnets along with other fish. Carp weighing over 10 kg have been caught both in fresh water and in bays of the Baltic Sea.
Vulnerability, threats and management: The status of the carp in Finland is not evaluated because of its foreign origin. It has, however, been a productive species when released into eutrophicated lakes and estuaries in the south of the country. Its future is uncertain due to the decline in rearing activities.
Comments: Worldwide annual production of carp in aquaculture ponds totals about two million tonnes. A genetically selected variety of Asian carp, the koi carp, is a popular ornamental fish kept in aquaria and garden ponds.
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