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Razorback Sucker
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Xyrauchen texanus |
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Razorback Sucker
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Xyrauchen texanus |
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Description: |
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The razorback sucker is one of a suite of now-endangered, endemic ‘big-river’ fishes of the Colorado River basin of western USA. Razorback suckers live for over 40 years reaching a meter in length and weighing 6 kilograms. They are brownish above and yellow to white below (sometimes the belly is mottled or salt and pepper) and adults develop a dorsal keel that differs from the humps present on some species of chubs (genus Gila) by the presence of a sharp edge or keel. Feeding on insects and planktonic food sources, the razorback sucker prefers slower moving off-channel habitat of rivers and is also found in impoundments.
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Status: |
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Federally listed as Endangered in 1991
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Historical Distribution: |
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Found throughout the Colorado and Gila River basins.
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Present Distribution: |
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The razorback sucker has now been nearly extirpated from Arizona. The only natural population found within Arizona is an old, declining population of less than 1,000 fish in Lake Mohave, Arizona-Nevada. A small population also exists in the Nevada portion of Lake Mead, Arizona-Nevada. In the upper Colorado River basin a couple of smaller natural populations exist in the Yampa and Green rivers of Utah and Colorado. A younger population of over 1,500 fish in Lake Mohave has been created by an augmentation program in Lake Mohave using larvae that were produced naturally in the lake. In addition, reintroduction programs have released hatchery raised fish into Lake Havasu, the Colorado River below Parker Dam, and the Verde River. Success of these programs has not been properly assessed.
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Research: |
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Although the razorback sucker was known to be in decline as early as the 1970s, the species was not listed in the hope that the species could be recovered without federal protection. Stocking efforts in the 1980s failed to augment populations. Since federal listing, ongoing stocking programs in the lower and upper Colorado River have had limited success.
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Literature Citations: |
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Federal Register (1980) Endangered and threatened wildlife and plants; notice of withdrawal of an expired proposal for listing of the razorback sucker. Fish and Wildlife Service 45: 35410.
Federal Register (1990) Endangered and threatened wildlife and plants; proposal to determine the razorback sucker (Xyrauchen texanus) to be an endangered species. Fish and Wildlife Service 55: 21154-21161.
Marsh P. C., Pacey C. A. & Kesner B. R. (2003) Decline of the razorback sucker in Lake Mohave, Colorado River, Arizona and Nevada. Transactions of the American Fisheries Society 132: 1251-1256.
Marsh P. C. & Tyus H. M. (1994) Razorback sucker. In: Life on the edge (eds. C. G. Thelander & M. Crabtree) pp. 372-374. BioSystems Books, Santa Cruz, California.
Minckley W. L. & Gustafson E. S. (1982) Early development of the Razorback Sucker, Xyrauchen texanus (Abbott). Great Basin Naturalist 42: 553-561.
Mueller G. A., Marsh P. C., Foster D., Ulibarri M. & Burke T. (2003) Factors Influencing Poststocking Dispersal of Razorback Sucker. North American Journal of Fisheries Management 23: 270-275.
Schooley J. D. (2004) Searching for Suckers! AZ-NM Chapter American Fisheries Society Newsletter 35: 2-3.
USFWS (1990) Razorback sucker (Xyrauchen texanus): Final rule. |
