Green River Regional Fish Information

Big Sandy River Restoration Project

The distribution of Bluehead sucker, Roundtail chub and Flannelmouth sucker, collectively known as the three species, has been dramatically reduced across the Colorado River Basin due to the introduction of nonnative species and habitat loss. A concrete fish barrier was constructed on the river in 2016 to prevent the movement of nonnative species, such as burbot. Make sure you stop and read this interpretive sign to learn more about the three species, how and why they need to be protected, and how you can help. The sign is located at the vehicle pullout on Highway 191 towards the town of Pinedale, WY, 7 miles north of the turnoff for Big Sandy Reservoir. The sign was installed by Green River Fisheries Biologist John Walrath and Pinedale Habitat Access Biologist Kyle Berg. 

Thank you to all the partners who made this sign and project possible: WGFD, BLM, WWNRT, Landowners of the Big Sandy River, Wyoming Governor's Office, Sublette County Conservation District, and the US Fish and Wildlife Service.


Native fish restoration project underway on Big Sandy

September 14, 2021


Since the early 2000s, the Wyoming Game and Fish Department has engaged in efforts to conserve and restore Flannelmouth and Bluehead suckers in their native drainages. These efforts are aligned with their responsibility  to conserve and enhance “all aquatic wildlife and their habitats for future generations.” The Green River fisheries management crew, with help from personnel from across the state, is taking steps over the next two weeks to eliminate threats to the future persistence of Flannelmouth and Bluehead suckers inhabiting the Big Sandy River upstream of Big Sandy Reservoir.
The plan entails chemically treating the river and reservoir with rotenone to eradicate nonnative species. The river is the primary habitat for the two native suckers which can hybridize with introduced white suckers and longnose suckers.  The reservoir is being treated to eliminate a large source of nonnative fish, especially the illegally introduced burbot.  White suckers and burbot are significantly reducing the fisheries potential in the reservoir: white suckers bind up the majority of resources in the reservoir and burbot consume trout. The sport fishery in the reservoir will benefit from their removal.  

Rotenone is a naturally occurring chemical found in the seeds and stems of several plants.  It is lethal to fish and other gilled life at very low concentrations but is not a concern for wildlife, livestock, humans, or pets.  It has been used by government agencies to kill fish in rivers and lakes in the United States since 1952.

The Wyoming Game and Fish Department has spent the previous two and half months salvaging native suckers from 56 miles of the Big Sandy River upstream of the reservoir. These fish are being held for safekeeping at two facilities.  Once all nonnative fish are removed from the river and reservoir, the native fish will be repatriated to the river. 

John Walrath, Fisheries Biologist for the Green River Region, understands why some people question the Department’s decision to spend time and money on Wyoming’s native nongame suckers and chubs, but cites the call for federal protection of wildlife species as the reason. 
"Populations of flannelmouth and bluehead suckers have declined in Arizona, Colorado, Nevada, New Mexico, Utah and Wyoming," Walrath said. "The six states have developed a range-wide conservation agreement and strategy with the goal of ensuring the persistence of bluehead sucker and flannelmouth sucker populations throughout their ranges. We believe that, as fisheries managers, we must stay proactive in the management of these two species to keep them from being petitioned for listing under the Federal Endangered Species Act. We do not want these native fish to become endangered, let alone go extinct."


- WGFD -



Anglers Kevin Spence (left) and Nick Walrath hold up some nice Tiger trout caught on High Savery near Baggs, Wyoming. 

Volunteers assist with fish sampling on Sulphur Creek Reservoir


Green River Fisheries Biologist John Walrath (Boat captain) and fish technicians Hunter Weidenborner and Mitch Magruder, Evanston Game Warden Nick Roberts and I&E Specialist Lucy Wold set nets on the reservoir to sample fish species, numbers, lengths and weights. Species included Bear River Cutthroat, White suckers, a few rainbow trout and a few walleye. The reservoir was rough, with high winds and white-caps, and it was wonderful to have the help of area summer school students and their teachers/chaperones. 




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WGFD Photos: Lucy Diggins-Wold

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WGFD Photos: Lucy Wold

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WGFD photos: Lucy Wold

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If you have a good day of catching small lake trout or burbot you might want to try one of the following recipes.


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If you have a recipe you would like to share with us and our readers, please contact John Walrath at:


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