Justification:
The habitat of this species has been extensively altered and fragmented, distribution and abundance of the species have declined over the long term, and number of locations is uncertain but may not exceed 10. Population size is unknown. Despite declines and existing threats, the extent of occurrence remains large, area of occupancy is somewhat more than 2,000 sq km, distribution is not severely fragmented, and trend appears to be relatively stable, so the species is listed as Least Concern..

Historically this species was recorded in 13 states of the Mississippi and Missouri rivers and their larger tributaries, including approximately 85 miles (136 km) of the lower Yellowstone River, 1,950 miles (3,120 km) of the main stem Missouri River (mouth to North Dakota), and about 1,150 miles (1,840 km) of the Mississippi River below the mouth of the Missouri River (south to southern Mississippi) (USFWS 2001); also the lower Kansas River in eastern Kansas (Page and Burr 2011).

Total abundance is unknown. The species is fairly common in the middle Missouri River, rare elsewhere (Page and Burr 2011). Benthic trawls indicate that this species comprises a significant proportion of the fish population at three locations in the Missouri River drainage (up to 42 percent of the catch) (USFWS 2001).

The species occupies approximately 54 percent (1,110 miles, 1,776 kilometres) of the historical range in the Missouri River drainage (USFWS 2001).

Recent surveys using benthic trawls suitable for small fishes indicate that the species is more widespread and common than previously believed (USFWS 2001); apparently stable in distribution and abundance in Missouri (see Figg and Bessken 1995), with viable populations in the Mississippi River (USFWS 2001).

Habitat includes sand and gravel runs of large rivers (Page and Burr 2011); continuously and heavily turbid, warm, large rivers with stable gravel and sand substrate; in shallows in strong current over fine gravel or sand.

Decline has resulted from human-induced changes in river conditions. Dams have flooded river habitat, altered temperature and flow regimes, reduced sediment transport and turbidity, fragmented populations, and reduced movement opportunities. Channelization has reduced habitat diversity and reduced overbank flooding. Pollution and water depletion from industry and agriculture may have altered water quality. Sand and gravel excavation have removed habitat and restricted fish movements in some areas. Further water depletion is likely to occur in the future due to energy development in the Upper Missouri River Basin, increased interbasin transfer of water, and increased municipal, industrial, and irrigation use. Dredging for channel maintenance and sand/gravel extraction will continue in new areas. May be negatively impacted by the numerous species of non-native fishes that have been introduced into the habitat (USFWS 1995). Ongoing and proposed conservation measures are likely to have a beneficial impact on Sicklefin Chub and Sturgeon Chub populations (see USFWS 2001 for details).

USFWS (1993) made the following recommendations: 1) protect the remaining free-flowing rivers with populations of the Sicklefin Chub from development and impoundment; 2) curtail of habitat loss on the Missouri and Mississippi rivers through habitat restoration and alteration of flow regimes; 3) investigate feasibility of propagation.