Xyrauchen texanus
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Xyrauchen texanus |
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| ( Abbott , 1860) |
Xyrauchen texanus is a largespecies of sucker carp nativeto North America . It is only endemic to the Colorado River basinin the southwestern United States .
distribution and habitat
The fish species was originally distributed in the entire catchment area of the Colorado River in the US states of California , Arizona , Nevada , Utah , Wyoming and Colorado to Baja California in Mexico . After water engineering measures, their occurrence was reduced to the Colorado River above the Grand Canyon , to Lake Mead , Lake Mohave and Lake Havasu on the lower reaches of the river. In 2012, specimens were surprisingly found in Grand Canyon National Park . The population there is probably in contact with the population below in Lake Mead, the exact distribution is the subject of studies in 2013 and 2014.
The fish have a wide habitat, from medium-sized flow channels, through backflows in rivers or streams with gravel, sand or even muddy bottom.
description
The sharp-edged bulge on the back between the head and dorsal fin is characteristic of the species. This bulge gave the genus Xyrauchen (from Greek xyreo "cuts like a knife" and also "neck") its name and the species its common name "Razorback Sucker" (razor-blade back suction carp). In some places it is also known as the “humpback sucker”.
Xyrauchen texanus can grow up to a meter long and weigh six kilograms. It has an olive-green to brown-black color on the back. The belly side is white to yellowish, during the mating season in males bright yellow to orange.
Way of life
The species has a long lifespan. Their maximum age is estimated at 40 years. Both Rogner and Milchner become sexually mature around the age of four. Spawning time is late winter or spring, usually when the water temperature is more than 14 ° C. The fish then go to their spawning areas such as Cottonwood Cove, Arizona Bay, Six-Mile Cove or Eldorado Canyon. The spawning process takes place in groups, there are two to 12 milkers for each Rogner, with the Rogner laying the eggs on the ground. The eggs have an adhesive that allows them to stick to the soil substrate. Rogner defend their clutch by creating light reflections with the retina of their eyes, which can chase the rival away. This defense behavior is specifically directed against other milkers. Rogner and predatory fish do not respond to these flashes of light. The animals feed on algae , insect larvae , plankton and detritus .
Endangerment status
The population of Xyrauchen texanus is threatened by habitat degradation and neozoa . The species, whose population only consists of a few thousand specimens, is classified as critically endangered because the population has declined by more than 80% within three generations. The species was classified as an endangered species by the state of California in 1974, and placed under the federal government's endangered species protection under the Endangered Species Act in 1991 by the US Fish and Wildlife Service . In Lake Mohave, the stock has increased to 3,000 specimens again through the rearing of young fish. In addition, Xyrauchen texanus was reintroduced in Lake Havasu, the Colorado River below Parker Dam and the Verde River .
After specimens were surprisingly found in 2012 and 2013 in the section of the Colorado River within the Grand Canyon National Park , specimens of Xyrauchen texanus marked with transponders were released in the national park in March 2014 . The scientists from the National Park Service and the US Fish and Wildlife Service hope that the tagged animals will join conspecifics so that the population can be found and studied more closely.
In spring 2014, for the first time in decades, larvae of Xyrauchen texanus were found in Colorado within the Grand Canyon after thorough investigations . Independent reproduction of the species was demonstrated in 9 of 47 locations examined.
Web links
- IUCN Red List Xyrauchen texanus
- Xyrauchen Texanus Recovery Plan, Utah State University
- WL Mingkley: Status of the Razorback Sucker, Xyrauchen texanus (Abbott) in the lower Colorado River basin, The Southwestern Naturalist (Engl.)
- Harold M. Tyus and Catherine A. Karp: Spawning and Movements of Razorback Sucker, Xyrauchen texanus, in the Green River Basin of Colorado and Utah, The Southwestern Naturalist (Engl.)
Notes and individual references
- ↑ a b c Xyrauchen texanus on Fishbase.org (English)
- ↑ National Park Service: Grand Canyon National Park - Razorback sucker (Xyrauchen texanus)
- ↑ a b Xyrauchen Texanus Recovery Plan, Utah State University
- ↑ a b IUCN Red List Xyrauchen texanus
- ↑ National Park Service: Grand Canyon National Park - Tagged Razorback Suckers Released in Grand Canyon , Press Release, April 14, 2014
- ^ Department of the Interior: Once Thought Locally Extinct, Endangered Razorback Suckers Discovered Spawning in Grand Canyon National Park , June 18, 2014