Silver carp
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Silver carp ( Hypophthalmichthys molitrix ) |
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| Hypophthalmichthys molitrix | ||||||||||||
| ( Valenciennes , 1844) |
The silver carp ( Hypophthalmichthys molitrix ) and bighead carp or Silberamur called, is a sociable open water fish from the family Xenocyprididae .
distribution and habitat
The silver carp originally comes from rivers and associated standing waters in East Asia, the Amur region and central China. However, it was released in many places outside of its original range, in Asia and in the 1960s also in Central Europe , often together with grass carp and marble carp . In the 1970s, the species was introduced to North American fish farms, from where it made its way into the Mississippi and quickly spread northward into the Great Lakes.
features
The most noticeable external features are the small, below the center of the head eyes and the large, strongly superior mouth cleft. The sideline is curved towards the abdomen. The top is greenish-gray in color, the belly and sides have a silvery sheen. Silver carp can reach a length of up to 1.30 m, but usually stay smaller. At around 15 times the length of the body, the intestine is extraordinarily long. The silver carp has strikingly small scales along a central longitudinal row (mLR) 110 to 124.
Number of fin rays :
- Dorsal I-III / 6-7
- Anal I-III / 10-14
There is no pronounced gender dimorphism .
Way of life
In their original range, silver carp spawn from May to July in flowing water between 23 and 24 ° C. The up to 500,000 eggs and the hatching fry are pelagic . After eating the yolk sac , the fry initially feed on zooplankton . From a size of about five centimeters, the switch to phytoplankton takes place . The smallest plants are filtered out through the gill spines that have grown together to form a fine network . The particle size of the food ingested can fall below 0.1 mm. Silver carp reach sexual maturity after three to five years. Natural reproduction is almost impossible under the climatic conditions of Central Europe . Under breeding conditions, they spawn from April to May.
Economical meaning
The introduction in Europe was connected with the expectation of being able to better control the rampant growth of planktonic algae in heavily eutrophied waters. However, the positive effects on water quality are negligible. Due to their low-fat, tasty meat, silver carp are suitable as food fish.
Silver carp as an invasive species in the US
Silver carp have spread very widely, especially in the USA. Due to their massive occurrence, they are in threatening food competition with the local fish fauna. As in Europe, they were originally intended to combat algae and plankton and were used in pond farms in Arkansas and Mississippi in the 1970s . Some specimens were able to escape from the closed systems into the Mississippi river system and have multiplied strongly due to the extensive lack of natural enemies. The Illinois River is currently the river with the highest density of carp in the world due to its expansion. Currently the silver carp are about to colonize the Great Lakes . The US Army was commissioned to prevent further spread by means of electronic underwater barriers and fences in the flooded area of Lake Erie . A budget of 80 million USD was made available for this. Measures such as deterrence through light and noise as well as targeted poisoning were unsuccessful. There are even plans to permanently close the lock and canal system between the Illinois River and Lake Michigan near Chicago .
The high population density favors accidents with motorized water sports enthusiasts who can collide with startled fish jumping high out of the water.
literature
- Günther Sterba : Freshwater fish in the world. Weltbild Verlag, Augsburg 1998, ISBN 3-89350-991-7 .
- Horst Müller: Fish of Europe. Neumann Verlag, Leipzig / Radebeul 1983, ISBN 3-7402-0044-8 .
- Roland Gerstmeier, Thomas Romig: The freshwater fish of Europe for nature lovers and anglers. 2. revised u. actual Edition. Franckh-Kosmos Verlag, Stuttgart 2003, ISBN 3-440-09483-9 .
Web links
- Silver carp on Fishbase.org (English)
- Fisheries & Aquaculture - Cultured Aquatic Species Information Program: Hypophthalmichthys molitrix (Valenciennes, 1844)
- Hypophthalmichthys molitrix in the Red List of Endangered Species of the IUCN 2013.1. Posted by: Zhao, H., 2011. Retrieved September 29, 2013.
Individual evidence
- ^ Silver carp invasion in Canada: The fish that came from abroad ( memento from October 19, 2010 in the Internet Archive ), tagesschau.de, message from October 16, 2010.
- ↑ Tyrolean pulled carp weighing more than 40 kg from the quarry pond, Standard, June 26, 2013
- ↑ Environment: Scary Monsters . In: Der Spiegel. 14/2011, pp. 118-119.
- ↑ Asian Carp Jumping, part 1 on YouTube
- ↑ That Will Leave A Mark on YouTube - Report on the ecological problem (English), with collisions with flying fish