Gila cypha
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| ( Miller , 1946) |
Gila cypha ( Engl . : humpback chub) is a fish from the carp family in North America. It only occurs in small isolated stretches of the Colorado River system, especially in Grand Canyon National Park . The Little Colorado River tributaryis the best spawning area. The type is available in the United States after the Endangered Species Act under the protection of species of the Federation and is from the United States Fish and Wildlife Service manages.
One specimen was accidentally found in the collection of the National Park Administration by Robert Rush Miller in 1942 and described by him as a separate species in 1946. The fish had been fished, groomed and added to the collection in 1932 by a park worker in Bright Angel Creek .
description
Gila cypha is slender in shape with a gray or olive-colored back and silver flanks and a white belly. It has a beak-shaped mouth, the upper lip of which protrudes significantly. The head is flat, the cheeks hollow. The species is characterized by the hump, which gives it its name in English, which begins above the gills and extends to the base of the dorsal fin . Like all fins, this is long and distinct. In the spawning season, the gill cover and the fins turn pink to red. It grows up to 38 cm.
It feeds on arthropods , smaller fish, diatoms , plankton and algae . It does not make any special demands on its normal habitat, fast and slow waters, water depths between one and 15 m and subsoils between sand and bare rock are assumed.
Related species
Gila cypha is closely related to Gila elegans (English Bonytail chub) and Gila robusta (English Roundtail chub). All three occur in the river system of the Colorado River, whereby G. cypha is adapted to the fastest flowing waters, G. elegans to medium and G. robusta to slow rivers. G. robusta only occurs in the lower reaches of the Colorado; it has been listed under the Endangered Species Act since 1980 . G. elegans lives in isolated occurrences in different parts of the Colorado and several tributaries.
Multiplication
Gila cypha can live up to 35 years and reaches sexual maturity at 2-3 years. It spawns from May to July. It depends on a sandy or rocky substrate, but probably also takes on gravelly ground. The water depth in the spawning grounds can be between 1.80 and 3.80 m, the flow speed can range from 15 to 30 cm per second.
However, the species is dependent on water temperatures above 14 ° C (up to 24 ° C with greatest success at 20 ° C) , which can no longer be reached in the fast-flowing waters below dams and in rivers that have deepened due to a lack of bed load .
Distribution and existence
Originally, Gila cypha was found in large parts of the Colorado River system in the western United States. In addition to the Colorado itself and Little Colorado, it was found in the Green River , Yampa River and White River . Since the construction of dams on the Colorado, in particular the Hoover Dam , Glen Canyon Dam and the dam wall at the Flaming Gorge Reservoir , the populations were initially isolated and then partially died out. The species has become extinct in around a third of the original range.
Today, the Colorado River in Grand Canyon National Park between the mouth of the Paria River and near the exit of the canyon is the habitat of the only larger population. It only spawns in Little Colorado near its mouth. Around 75% of the total population lives here. It is classified as viable and self-sustaining.
Isolated small populations are also preserved above in Black Rocks Canyon and Westwater Canyon of Colorado, Gray Canyon and Desolation Canyon of the Green River, and Yampa Canyon of the Yampa River. However, they are considered very old and the survivability of the populations is questionable. After evaluating the 2008 data, the five populations in the upper Colorado River were classified as non-self-sustaining.
The total population of the species was estimated at under 1500 adults in 2001.
In Shinumo Creek , another tributary of the Colorado River in the Grand Canyon National Park, a small population was located in 2009. Another population was established in Havasu Creek in 2011, also in Grand Canyon National Park .
The total population of Gila Cypha is given as between 6000 and 10,000 animals for 2008, this corresponds to an increase of around 50 percent between the 2001 and 2008 record. Accordingly, it looks like the decline in the population that was observed between 1989 and 2001 was stopped and the species stabilized. More than 90% of the population live in Little Colorado or around its immediate estuary in the Colorado River.
Protection status and nature conservation measures
Gila cypha was one of the first species to be included in federal conservation under the Endangered Species Conservation Act , and in 1973 it was protected by the subsequent Endangered Species Act . In 1990, a coordinated plan to increase the population ( Humpback Chub Recovery Plan ) was decided and in 1994 its remaining habitat was determined and placed under observation ( final critical habitat ).
The experiments with the targeted opening of the dam gates of the Glen Canyon Dam to flood the Grand Canyon in 1996, 2004, 2008 as well as in November 2012 and November 2013 were carried out specifically to protect Gila cypha . The floods should deposit debris to form sandbars and riparian zones , in which shallow water areas warm up enough for the species to spawn again in Colorado.
In June 2009, 300 animals that had been caught in Little Colorado shortly after hatching the previous year were released into Shinumo Creek . The creek was chosen because it is separated from the Colorado River by a waterfall, so non-native Colorado fish cannot penetrate the Shinumo, which would endanger the spawning. Rainbow trout have been removed from Shinumo Creek whenever possible. More juveniles followed in 2010, 2011 and 2013. In 2011, 2012 and 2013 the Havasu Creek was occupied. The measure is accompanied by biomonitoring , the animals wear passive transponders under their skin, and antennas have been installed in the river. Initial data from July 2009 suggest that the vast majority of the animals will have settled in in the new habitat within a few days. The further development of the populations is promising.
The measures, in particular the flooding of the canyon, the control of non-native species in the mouth area of the Little Colorado River and a general increase in temperature due to drought in the last decade are cited as factors for the stabilization of the population.
literature
- US Fish & Wildlife Service: Humpback chub (Gila cypha) 5-Year Review: Summary and Evaluation , Upper Colorado River Endangered Fish Recovery Program 2011
Web links
- Gila cypha on Fishbase.org (English)
- US Fish and Wildlife Service: Gila cypha
- Gila cypha inthe IUCN 2013 Red List of Threatened Species . Listed by: NatureServe, 2012. Retrieved December 14, 2013.
Individual evidence
- ^ RR Miller, Gila cypha, a remarkable new species of cyprinid fish from the Colorado River in Grand Canyon, Arizona . In: Journal of the Washington Acadademy of Sciences, Volume 36, No. 12, p. 409-415.
- ^ Stephen Carother, Bryan Brown, The Colorado River through Gand Canyon , University of Arizona Press, 1991, ISBN 0-8165-1232-9 , p. 95
- ^ Stephen Carother, Bryan Brown, The Colorado River through Gand Canyon , University of Arizona Press, 1991, ISBN 0-8165-1232-9 , p. 96 f.
- ↑ USFWS 2011, page 6
- ↑ USFWS 2011, page 10
- ^ A b Dean W. Blinn, N. Leroy Poff: Colorado River Basin . In: Artur C. Benke, Colbert E. Cushing: Rivers of North America . Elsevier, 2005, ISBN 0-12-088253-1 , page 493
- ↑ a b c d e National Park Service: Grand Canyon National Park - Humpback Chub Translocation Experiment in Shinumo Creek (accessed August 24, 2009)
- ↑ USFWS 2011, page 8
- ↑ a b c USGS Grand Canyon Monitoring and Research Center: Humpback Chub , as of November 2011
- ^ National Park Service: High-Flow Experiment
- ↑ National Park Service: Second Translocation of Endangered Humpback Chub to Shinumo Creek to Occur in Late June (accessed July 2, 2010)
- ↑ National Park Service: Grand Canyon National Park - Preliminary Data Indicate Humpback Chub Translocation Successful to Date (accessed August 24, 2009)