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North Dakota's

Federally Listed Endangered, Threatened, and Candidate Species – 1995

Western Silvery Minnow (Hybognathus argyritis )

GIF -- species photo gif--species map

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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:
Western silvery minnows were first reported in North Dakota in 1930 in the Red River. Their historic U.S. range extended from Montana to Ohio and southward to the Gulf States. They were common in small streams throughout Minnesota, especially those with muddy bottoms.

Present Status:
Western silvery minnows are most often collected in large prairie streams in western North Dakota. They still inhabit some unchannelized and channelized portions of the Missouri and Mississippi Rivers. Typically they are collected from the Little Missouri and Cannonball Rivers. The western silvery minnow is also found in lakes Audubon, Sakakawea, and Oahe.

Western silvery minnows inhabit larger prairie streams with silt or sand bottoms and in the backwaters and pools of large streams and in the quiet reaches of their tributaries. The western silvery minnow is often found in association with the plains minnow, silver and flathead chubs, and the red, sand and emerald shiners.

Life History:
Western silvery minnows spawn from early May through June at temperatures of 55° to 69° F. Prior to spawning, adults migrate to well-vegetated lagoons or slow moving lower reaches of tributary streams. The western silvery is typically found in water less than one foot in depth and shallow shore waters heavily vegetated witb emergent grasses and reeds providing effective cover. The western silvery minnow is 3 to 5 inches in length and is very similar to the central silvery minnow in appearance with a slightly smaller eye. Detailed food studies have not been conducted but bottom ooze and algae have been reported from the stomachs and probably are the main food items. The western silvery minnow may constitute important forage for the young of game species inhabiting the same habitat.

Aid to identification:
Very similar to the central silvery minnow but differing in these respects: eye slightly smaller, its diameter going 4 to 4.8 times into head length; diameter of eye less than width of mouth opening; basioccipital process (a backward extension of bone at lower rear margin of skull) broad and blade-like, its back margin straight or only slightly concave.

Reasons for decline:
The greatest threats to the western silvery minnow are nonpoint source pollution, water depletion from irrigation, degradation of riparian areas, and mainstem impoundments impacting natural flow regimes.

Original references to the western silvery minnows occurrence in the Red River were probably erroneous. The accounts were probably of the central silvery minnow.

Freshwater fishes of Canada, by W. B. Scott and E. J. Crossman, 1973. Fisheries Research Board of Canada. Bulletin 184.
The Fishes of Missouri, by W. L. Pflieger, 1975. Published by the Missouri Department of Conservation.
Northern Fishes, by S. Eddy and T. Surber. 1943. University of Minnesota Press.

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