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North Dakota's

Federally Listed Endangered, Threatened, and Candidate Species – 1995


Flathead Chub (Platygobio gracilis)

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:
The historical range of the flathead chub extends from Tennessee and Arkansas to Montana and Wyoming. Like the sicklefin and sturgeon chub, it does not ascend the Mississippi River above the mouth of the Missouri.

Present Status:
Flathead chubs are most often collected in large streams and rivers in western North Dakota. They still inhabit some unchannelized and channelized portions of the Missouri and are typically collected from the Little Missouri, Yellowstone, Cannonball, and Heart rivers and Cedar, Cherry, and Beaver (Golden Valley County) Creeks. The flathead chub is also found in Lake Sakakawea.

Habitat:
The minnow inhabits a diverse range of habitats. In the Missouri River it is found in more or less continuously turbid waters where the current is swift and the bottom is composed of sand or fine gravel. But in portions of its range it is collected in pools with moderately clear water, little current, and bottoms composed of coarse gravel and bedrock.

Life History:
Flathead chubs are an active minnow, moving about more or less constantly, often in mixed schools with other big-river minnows. Flathead chubs rely on external taste buds to locate food in turbid water. The diet of the flathead chub is reported to consist mostly of terrestrial insects that fall into the water, supplemented by lesser quantities of other small invertebrates and plant material. In Canada water boatman (Corixidae) make up 35% of the diet. In Missouri, the fish is thought to spawn in July or August, but no studies of spawning have been conducted in North Dakota.

Aid to identification:
The flathead chub is a slender minnow with small eyes and sickle shaped pectoral fins. The head is distinctively wedge shaped in profile. Snout is flattened and rather pointed. The mouth has a small barbel at the corner. Anal fin has 8 rays. Lateral line scales number from 44 to 56. Eye diameter is much less than length of snout. The flathead chub is commonly 3 to 7 inches long with a maximum of 12 inches.

Reasons for decline:
The greatest threats to the flathead chub are nonpoint source pollution, and mainstem impoundments impacting natural flow regimes. Other threats across its range include dewatering of rivers ffom irrigation and degradation of riparian areas.

Comments:
The flathead chub was resumed to the genus Platygobio in 1989 and is sometimes referenced in the literature as Hybopsis gracilis. The flathead chub is also known as the Saskatchewan dace. In Iowa, it is a preferred bait fish for blue catfish because of its size and hardiness.

References:
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.
Common and Scientifc Names of Fishes from the United States and Canada. 1991. American Fisheries Society Special Publication 20.


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