The native fish community remains intact because the river

"The Powder River represents a unique river system…. Consequently, it has a fish community that is also unique. " Hubert, W.S. The Powder River: A relatively pristine stream on the Great Plains.

is relatively undisturbed by water development and channelization, and because the existing flows, turbidity, and water quality remain primarily natural. This is in stark contrast to most other rivers in the Great Plains, which are marked by alien (nonnative) fish species and reductions or loss of the naturally occuring species as a result of habitat changes due to water development, water diversions, other human impacts, and alien species competition or predation.

Of the native fish species in the Powder River, one-the Sturgeon Chub-is globally imperiled. Another native fish, the Western Silvery Minnow, was found in a 1993 survey to be in drastic decline in Wyoming and has experienced serious declines in other states as well. The Shovelnose Sturgeon, Goldeye, Sauger, and Burbot are also rare or uncommon in Wyoming and are of conservation concern. Below we present additional information on several of these species (adapted from Fishes of Wyoming and other sources listed).

Sturgeon Chub, Macrhybopsis gelida

The Sturgeon Chub is a small minnow native to Wyoming that occurs primarily in the Missouri River drainage. Due to habitat changes and alien species, it currently inhabits only 20% of its historic range. In Wyoming, the Sturgeon Chub is known to occur only in the Powder River, and in one location on Crazy Woman Creek just upstream from its confluence with the Powder. It was collected from the Big Horn River in the late 1960's and is listed in the Wyoming Game and Fish Department's database as occurring there today. However, Fishes of Wyoming reports that this species is probably now extirpated from the Bighorn drainage. It is known to have existed in the North Platte River before the turn of the century but appears to be extirpated from this river as well.

According to Fishes of Wyoming, "[T]he sturgeon chub is one of the rare species of fish found in the state and the existing population in the Powder River merits protection." The Sturgeon Chub is ranked G2/S1S2 (imperiled globally and critically imperiled in the state) by the Natural Heritage Network. In 1989, the Sturgeon Chub was identified as a species of special concern by the American Fisheries Society.

The Sturgeon Chub requires large, free-flowing rivers characterized by swift flows, highly variable flow regimes, braided channels, high turbidity and sand/fine gravel substrates. Altering the water temperature, flow timing and magnitude, turbidity and chemical composition could harm these rare fish or allow harmful nonnative fish to become established.

Western Silvery Minnow, Hybognathus argyritis

The Western Silvery Minnow is found in the upper Missouri River drainage.

Western Silvery Minnow

In Wyoming, this species is found only in the Powder and Little Missouri River drainages according to Fishes of Wyoming. This fish was found in Patton's mid-1990s survey to be in drastic decline, occurring in only 2 waters sampled. According to the Wyoming Game and Fish database, Western Silvery Minnow occurs in only 8 streams in the entire state. It was known to inhabit the Big Horn River, but has not been found there since the construction of the Big Horn Reservoir. The Western Silvery Minnow is ranked S2 (imperiled in the state) by the Wyoming Natural Diversity Database. It is also ranked NSS1 by the Wyoming Game and Fish Department (WGFD), which is the highest conservation status ranking given by the WGFD.

Western Silvery Minnows prefer protected areas in large, turbid rivers and prairie streams and are typically found in water less than one foot deep and shallow shore water heavily vegetated with emergent grasses and reeds. The greatest threats to Western Silvery Minnows are "nonpoint source pollution, water depletion from irrigation, degradation of riparian areas, and mainstem impoundments impacting natural flow regimes." Coalbed Methane development and production would be sources of nonpoint source pollution and would almost certainly alter the natural flow regime, and could degrade riparian areas and aquatic vegetation important to this species.

Shovelnose Sturgeon, Scaphirhynchus platorynchus

The Shovelnose Sturgeon can be found in the Mississippi River drainage. It is rare in Wyoming, being found in only three streams: the lower Powder River, Crazy Woman Creek, and Clear Creek. The latter two are tributaries to the Powder. The Sturgeon is considered critically imperiled in Wyoming by the Wyoming Natural Diversity Database. It is ranked very high by the Wyoming Game and Fish Department (WGFD) as well. The preferred habitat of the Shovelnose Sturgeon is at or near the bottom of large rivers with a sand substrate.

Goldeye, Hiodon alosoides

The Goldeye ranges across much of eastern North America but are relatively rare in Wyoming. In this state, they are found "in the Powder, Little Powder, and Little Missouri Rivers, and in Clear and Crazy Woman Creeks. It has been extirpated from the North Platter River in Wyoming," according to Fishes of Wyoming. Patton found the Goldeye only 5 rivers in the 1990's, while the WGFD database lists Goldeye in only 4 waters. Because the Goldeye is relatively rare, and because it has been completely eliminated from the North Platte River, we are concerned about its continued survival and consider it to be a conservation priority. Goldeye prefer large rivers and associated backwaters and marshes, as well as shallow waters of larger lakes and reservoirs.

Other Powder River Native Fish Information from the Scientific Literature

"One aspect of habitat management is to protect the tributaries to the Powder River. Tributaries provide spawning and nursery habitat for riverine fishes… they support unique fish assemblages…. Seasonal movement of riverine fishes into tributaries may be essential to the continued maintenance of several species, such as shovelnose sturgeon, goldeye, river carpsucker, shorthead redhorse, channel catfish, and sauger….

"A second aspect of habitat management is preservation of existing flows, turbidity, and water quality in the Powder River. The endemic fishes in the Powder River have evolved life history strategies that allow them to survive in extreme conditions. Water development that alters discharge patterns, reduces turbidity, changes water quality, modifies sediment transport, or blocks migratory routes for fish is likely to result in changes in the fish community.

"Smith (1988) made several recommendations regarding habitat management in the Powder River system: (1) prevent dewatering of tributaries in the summer caused by irrigation; (2) prevent dams from being constructed that provide barriers to fish movement, serve as sediment traps, and alter water quality; and (3) prevent alteration of natural stream channels through channelization and other anthropogenic modifications." All three quotes from Hubert, W.S. 1993.

"In an inventory of all streams in the Great Plains of Wyoming, the Powder River was found to support the most intact assemblage of fish species. Notable among these is the Sturgeon Chub, a globally rare species…" The Nature Conservancy. 1999.

References

Federal Register. January 18, 1995. Endangered and Threatened Wildlife and Plants; Notice of 90-day finding on the Petition to List the Sturgeon Chub and Sicklefin Chub as Endangered. U.S. Fish and Wildlife Service/Government Printing Office, Washington, DC.

Fertig, Walter and Gary Beauvais. 1999. Wyoming Plant and Animal Species of Special Concern. Wyoming Natural Diversity Database. University of Wyoming, Laramie.

Hubert, W.S. 1993. The Powder River: A relatively pristine stream on the Great Plains. Pp. 387-395 in Proc. of the symposium on restoration planning for the rivers of the Mississippi River ecosystem. (Hesse, L.W., C.B. Stalnaker, and N.G. Benson, tech eds). Biological Report 19. U.S. Dept. of the Interior, National Biological Survey, Washington, D.C.

The Nature Conservancy. 1999. Ecoregional conservation in the northern Great Plains steppe.

Patton, Timothy M. 1997. Distribution and Status of Fishes in the Missouri river Drainage in Wyoming: Implications for Identifying Conservation Areas. Ph.D dissertation. Department of Zoology and Physiology, University of Wyoming, Laramie.

Stewart, Daniel D. 1981. The Biology of the Sturgeon Chub in Wyoming. Master's Thesis. Department of Zoology and Physiology, University of Wyoming, Laramie.

U.S. Geological Survey Northern Prairie Wildlife Research Center. No Date. North Dakota's Federally Listed Endangered, Threatened, and Candidate Species--1995. http://www.npwrc.usgs.gov/resources/distr/others/nddanger/species/hyboargy.htm.

Wyoming Game and Fish Department. 1998. Streams and Lakes Database. Wyoming Game and Fish Department, Cheyenne, WY.