Northern Prairie Wildlife Research Center
Federally Listed Endangered, Threatened, and Candidate Species 1995
Greater Redhorse (Moxostoma valenciennesi)
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- Status: Former Candidate (Note: As of February 28, 1996, this species is no longer listed as a Candidate species. However, it remains a species of management concern.)
- Historical Status:
- The greater redhorse is found
from the Great Lakes to St. Lawrence River region to Ohio and Kentucky. The western extension of its range includes North and South Dakota.
- Present Status:
- The greater redhorse has been found
in the Red, Maple and lower Sheyenne Rivers. However, there have been no recent accounts of the greater redhorse in North Dakota. The Nature Conservancy lists the greater redhorse as G3. (A G3 ranking indicates that this species is either very rare or found in a restricted range).
- The greater redhorse prefers large streams having clear waters throughout most of the year and bottoms of clean sand, gravel or boulders. Less is known of the biology of this species than any of the redhorse.
- Life History:
- The greater redhorse is the largest of the
redhorse reaching over 12 pounds but averaging only slightly over 2 pounds. It is a spring and summer spawner, from May to early July in Canada, and spawns in moderately rapid streams. Males arrive on spawning grounds early and establish territories. Eggs are scattered. Young of year tend to be less than three inches with the longest specimen collected measuring 24.5 inches. The greater redhorses main food items include invertebrates, immature insects, worms, and mollusks.
- Aid to identification:
- Very similar to other
redhorse, the predominant feature is a deep red tail. The greater redhorse also has deep red dorsal and caudal fins which are lighter in younger individuals. The greater redhorse also has a wide lower lip. The lower lip is 2 1/2 times width of upper lip. There are no teeth in the mouth, pharyngeal teeth are heavy but compressed and comb-like. Gill rakers range in number from 27 to 31. Scales are cycloid, large, not crowded anteriorly, each scale base has a definite dark crescent. There are approximately 42 to 45 scales in the lateral line; lateral line complete. Swim bladder has three chambers. Nuptial tubercles on males are confined to anal and caudal fins.
- Reasons for decline:
- The greatest threat to the
greater redhorse is alteration of habitat due to lowhead dams, channelization, increased water velocities, nonpoint source pollution, and degradation of riparian areas. Runoff in the Red River basin has increased the turbidity of the Red, Maple and Sheyenne Rivers.
- Today, the greater redhorse population in North Dakota may only be found in the lower Red River.
- Freshwater fishes of Canada, by W. B. Scott and E. J. Crossman, 1973. Fisheries Research Board of Canada. Bulletin 184.
Endangered, Threatened, and Peripheral Wildlife of North Dakota, by M. G. McKenna and R. W. Seabloom. 1979. Institute for Ecological Studies, University of North Dakota Research Report No. 28.
Northern Fishes, by S. Eddy and T. Surber. 1943. University of Minnesota Press.
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