One of the Wyoming Game and Fish Department’s largest native fish restoration projects is giving two native species a chance to sustain their populations in southwest Wyoming.
Bluehead sucker and flannelmouth sucker are native to the Big Sandy watershed. Few people are aware of these lesser-known fish, though, because they haven’t seen them, nor are the fish readily caught by anglers. These fish have been sampled in Big Sandy since the 1970s, however, data was typically collected for gamefish, and historical information about native, nongame fish was limited.
John Walrath, Game and Fish fisheries biologist, holds a bluehead sucker during salvage operations in the Big Sandy watershed. (WGFD photo)
Bluehead and flannelmouth suckers are Species of Greatest Conservation Need in Wyoming, which means Game and Fish makes extra efforts to help their populations stabilize and grow through focused projects. Their populations have declined dramatically throughout their native ranges in Wyoming due to loss of habitat, and interaction with nonnative fish such as white sucker, longnose sucker, burbot and creek chub. Burbot were also shown to have fed on bluehead and flannelmouth suckers. Hybridization of bluehead and flannelmouth suckers with the nonnative sucker species in the drainage also was a concern.
To restore these native fish, Game and Fish conducted a salvage operation that involved capturing thousands of bluehead and flannelmouth suckers and returning them to the water after undesirable fish species were removed. The project spanned 52.5 miles of river above the Big Sandy Reservoir, provides benefits for some more common sportfish and was made possible by a lot of work and cooperation among Game and Fish, landowners and partners.
GETTING STARTED
Game and Fish started work to identify where these native suckers were in 2003, along with an assessment of other nongame fish. This effort identified four primary basins: Big Sandy River, Little Sandy River, Muddy Creek and Bitter Creek.
“Those were the areas where we felt we could make the biggest difference for the two sucker species,” said Kevin Gelwicks, Game and Fish assistant fisheries management coordinator.
In 2009 and 2010, Game and Fish personnel mechanically removed undesirable species. With this method, at least four people operated a cataraft with electrofishing equipment. Fish were stunned, put in a livewell on the raft and sorted. Native species were returned to the water, but nonnative species were not. Mechanical removal efforts in the entire salvage area in 2009 removed more than 1,000 longnose suckers and 1,600 white suckers. However, those species rebounded and large numbers of both were in the salvage area a decade later — along with a high proportion of hybrid suckers.
In 2021, fisheries crews conducted a salvage effort, and 6,221 bluehead and flannelmouth suckers were salvaged — 94 percent of those fish were flannelmouth suckers. Those fish were taken to temporary homes at the Game and Fish’s East Fork facility near Boulder and to the University of Wyoming’s Red Buttes Biological Laboratory in Laramie.
The majority of the native sucker species salvaged in this project were flannelmouth suckers. (WGFD photo)
SALVAGE SPECIFICS
John Walrath, Game and Fish fisheries biologist in the Green River Region, headed this salvage project. In Walrath’s administrative report to the department, Walrath said three size groups for bluehead and flannelmouth suckers were selected: less than 4 inches, 4-14 inches and greater than 14 inches.
Salvage work started on July 6, 2021, and was completed Sept. 15. A typical work week consisted of one day of preparation and travel to base camp, followed by three days of electrofishing and a half-day of travel back to the town of Green River. As time went on, water flows throughout the salvage area declined, which was a challenge for personnel. Another challenge for native fish survival and logistical planning was water temperatures in the river that ranged from 50-55 degrees in the morning to more than 70 degrees by mid-afternoon on sunny days. Water in the stock truck that transported the salvaged fish was filled each morning with water in the 50-55 degree range, and by midafternoon it would be 5-7 degrees warmer. Mortality of fish increased the later salvage occurred in the afternoon. There also was high juvenile mortality of salvaged fish, especially those less than 2 inches long.
Low water levels during the salvage were a challenge to workers. (WGFD photo)
Trout were also salvaged during the project along the upper 13 miles of the project area. Salvage efforts began after a picket weir was installed Aug. 30, 2021, on Bureau of Land Management land and were completed Sept. 13. The same electrofishing gear for the native suckers was used for the sportfish. A total of 636 trout were salvaged and relocated above the treatment area in the river on public land and in a privately owned pond.
Once the native fish and sportfish were salvaged from the river, fisheries personnel worked to remove undesirable species. The project crossed a mix of private and public land, and in the winter of 2020, all the landowners granted Game and Fish permission for a rotenone treatment. Rotenone is an organic compound found in the roots of several plant species and is commonly used as a treatment to kill fish. Rotenone treatments were conducted in the fall of 2021-22.
Rotenone was used to remove undesirable fish species during the salvage project. (WGFD photo)
HOLDING PATTERN
Holding the native fish posed several challenges. Getting them to their holding facilities was stressful for the fish, and some died during transport. Others didn’t live long enough to return to their native waters after 2½ years in captive facilities. Gelwicks said some disease issues at East Fork made Game and Fish move many of the fish to Red Buttes Environmental Biology Laboratory in Laramie.
Native suckers were held in holding tanks and taken to captive facilities before being transported back to the wild. (WGFD photo)
“It was a challenge keeping the fish alive,” Gelwicks said. “We don’t have a broodstock for these native species of the Big Sandy, so that’s why we tried to keep as many younger fish alive prior to their release.”
In May 2024, all remaining small native suckers at East Fork were sorted to ensure only pure native suckers remained on station. When these fish were salvaged in the summer of 2021, their average length was about 1½ inches long. After nearly 2½ years in captivity, they grew to just under 4 inches.
A RETURN HOME
From October 2022-May 2024, 2,109 native suckers were returned — also known as repatriated — to the Big Sandy River. Ninety-one percent were flannelmouth suckers, and most of those were juveniles and subadults. Although there were fewer bluehead suckers, their survival rate in captivity was 62 percent compared to 49 percent for flannelmouths. Blueheads also had less issues with disease while in captivity. All fish were sorted prior to being repatriated to ensure only pure flannelmouth and bluehead suckers went back in. Genetic samples were also submitted for analysis as a verification for field identification and disease testing was completed to ensure pathogens were not being transported.
More than 2,300 flannelmouth and bluemouth suckers were returned to the Big Sandy River from October 2022-May 2024. (WGFD photo).
In August 2024, Walrath led a group of workers to see how the native suckers were doing after repatriation. Eight sites were sampled, and multiple size classes of bluehead and flannelmouth suckers were sampled. No adult fish were found, but young-of-the-year flannelmouths were sampled in the bottom half of the treatment area and landowners reported seeing schools of small suckers in the upper half.
“This is encouraging as it means adults repatriated in October 2022 successfully spawned,” Walrath said in his report to the department.
Many of the native suckers were found around overhanging willows. An adult bluehead sucker was also confirmed via snorkeling on a section of the river on private land. No white or longnose suckers were observed.
Game and Fish worked with the BLM, Trout Unlimited, U.S. Fish and Wildlife Service, University of Wyoming, landowners and personnel at fish hatcheries in Colorado and Utah to complete this momentous project.
The landowners — Pete and Sue Arambel, Tom and Mike Triplett, Dale Thrash and John and Joy Erramoupse — were awarded the Game and Fish’s Landowners of the Year in 2024 for their cooperation.
“This project is something we’re really proud of, and wouldn’t have been possible without landowner cooperation and the hard work of countless individuals,” Gelwicks said. “This project was not easy, but will safeguard the future of native flannelmouth and bluehead suckers in Wyoming.”
— Robert Gagliardi is the associate editor of Wyoming Wildlife magazine.