Mylopharodon conocephalus

Mylopharodon conocephalus
Mylopharodon conocephalus
Systematics
without rank: Otophysa Order : Carp-like (Cypriniformes) Subordination : Carp fish-like (Cyprinoidei) Family : White fish (Leuciscidae) Genre : Mylopharodon Type : Mylopharodon conocephalus
Scientific name
Mylopharodon conocephalus
( Baird & Girard , 1854)

Mylopharodon conocephalus , also hardhead or Sacramento Blackfish, is a carp fish from North America .

Systematics

Mylopharodon conocephalus was previously incorrectly described as Gila conocephala in the San Joaquin River in 1854 and then renamed again to Mylopharodon robustus. Although Mylopharodon robustus was then classified as a separate species, Mylopharodon is a monotypic genus according to Jordan. Only in 1991 did electrophoretic studies by Avise and Ayala, as well as morphometric analyzes by Mayden et al. the realization that Mylopharodon conocephalus is related to the Sacramento Squawfish, but different enough to belong to an independent genus.

So there is a certain genetic relationship between Mylopharodon conocephalus and Ptychocheilus ssp.

description

The hardhead has a streamlined body and a brown, bronze or bluish color on the back. The fins can be reddish or orange in color. Mylopharodon conocephalus grows to an average of 35 centimeters. Hardheads are often seven to eight centimeters long in the first year of life, but the speed of growth slows down in the following years, for example they become 30 centimeters long after four years. In the Pit and Feather Rivers, however, they only reach this size on average after six years. Hardheads from the Feather River with a length of 44 to 46 centimeters are already nine to 10 years old. In the Sacramento River, they are likely to get older and bigger. The largest specimens, weighing 10 kilograms and one meter in length, come from the Sacramento River and Russian River.

distribution

In North America, the hardhead is endemic to California . There it is distributed in the river system of the Sacramento River and San Joaquin River , Kern River in the Russian River and Napa River . Furthermore, it occurs in the Merced Canyon of the Yellowstone National Park or in smaller rivers of the Californian mountain region of the Sierra Nevada up to approx. 1,500 meters Mylopharodon conocephalus is particularly common in reservoirs at medium altitude such as the Redinger and Kerkhoff Reservoirs in the San Joaquin River. While the fish species was still widespread in California in the early 20th century, hardheads now live in small isolated local populations in many places.

Way of life

The fish often live in company with Sacramento Pikeminnows or Sacramento Suckers. Young fish like to stay on shallow edges, the transition from fast-flowing stretches of water to calmer ones. Adults, on the other hand, prefer the lower half of the water column. The hardhead prefers deep pools with sand or rock bottom from small to large rivers of the flatlands or medium altitudes of 10 to 1,400 meters. They can also be found in clear lakes and some reservoirs. Mylopharodon conocephalus is often found in stretches of water with medium flow velocity. The water temperature should not exceed 20 ° C, as the species is dependent on high oxygen levels. However, the ideal water temperature in summer is 24 to 28 ° C. In Britton Reservoir / Shasta County, hardheads often appear motionless in surface water, so that their behavior makes them the preferred prey of eagles that nest in the surrounding forests. While young fish feed on small animals, algae or aquatic plants, adult specimens also eat water snails, insects such as fish. B. Mayflies and occasionally smaller prey fish, as studies from the Shasta Reservoir show. Ontogenetic studies of the tooth structure show a change in your eating habits. The sexual maturity of the fish begins at the age of three. The spawning season takes place between April and May, when the fish migrate upstream into the tributaries. Female animals produce between 7,000 and 24,000 eggs. In order to find suitable spawning grounds, the hardhead undertakes hikes of up to 35 kilometers in length.

use

The hardhead is of no greater importance either as a food fish or as a sport fish.

Hazardous situation

In 1986, in order to “protect” the game fish populations of trout and Pacific salmon, Rotenone was introduced into some California rivers to combat “brood predators” such as the hardhead. In many places, however, the population of the fish species has recovered. If there are many introduced sunfish in the water , the hardhead population is declining, which is due to the perch's predatory behavior. For example, if they are still relatively common in Upper Lake Britton, their number of individuals in Lower Lake Britton is correlated with the number of sunfish, which find ideal living conditions there. Anthropogenic interventions such as dam construction and the resulting change in the flow rate of a river or introduced foreign fish species can affect the population of Mylopharodon conocephalus .

literature

• Peter B. Moyle: Inland Fishes of California: Revised and Expanded, University of California Press, 2002, ISBN 978-0520227545 .

Web links

• [1] (PDF; 4.7 MB) Ecology of some Native and Introduced Fishes of the Sierra Nevada Foothills in Central California

Notes and individual references

1. ↑ ^{a b c d} Mylopharodon conocephalus on Fishbase.org (English)
2. ↑ ^{a b c d e f g h i j k l m n o p} Fish Species of Special Concern in California http://www.dfg.ca.gov/habcon/info/fish_ssc.pdf
3. ^ DS Jordan and CH Gilbert: Synopsis of the fishes of North America, Bull. US Nat. Mus, 1882, 16: 1-1018
4. ↑ JC Avise, JJ Smith and FJ Ayala: Adaptive differentiation with little genic change between two native California minnows, 1975, Evolution 29: 411-426
5. ^ RL Mayden, WJ Ra and DG Buth: Phylogenetic systematics of the cyprinid genera Mylopharodon and Ptychocheilus: comparative morphometry, 1991, Copeia 1991: 819-834
6. ↑ Phylogenetic Systematics of the Cyprinid Genera Mylopharodon and Ptychocheilus: Comparative Morphometry at http://www.jstor.org/pss/1446409
7. ^ Fishing World Records
8. ↑ http://www.yosemite.ca.us/library/fishes/hardhead.html
9. ↑ Ecology, Assemblage Structure and Status of Fishes in Streams Tributary to the San Francisco Estuary, California at http://www.sfei.org/sites/default/files/general_content/No530_Leidy_FullReport_revised_0.pdf#page=8
10. ↑ ^{a b} Archived copy ( memento of the original dated June 1, 2009 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
11. ↑ ^{a b} Archived copy ( memento of the original from July 23, 2010 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. 
12. ↑ Movements and Reproduction of Hardhead and Sacramento Squawfish in a Small California Stream at http://www.jstor.org/pss/30055225
13. ↑ 2005 Hardhead (Mylopharodon conocephalus) Surveys in the South Fork American River, El Dorado County / California at http://www.project184.org/doc_lib/documents/2008/2005HardheadMonitoringReport.pdf  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.  
14. ^ Peter B. Moyle: Inland Fishes of California: Revised and Expanded, University of California Press, 2002, p. 152