2 aquatic invasive species found in Flaming Gorge Reservoir

    (Green River, WY) 一 The Wyoming Game and Fish Department has verified the presence of two aquatic invasive species in Flaming Gorge Reservoir 一 curly pondweed and New Zealand mudsnails. Both species of AIS have been found in Wyoming before, however this is the first time New Zealand mudsnails have been documented above the Flaming Gorge dam. Game and Fish AIS personnel were able to confirm the presence following tips from the public.

    In mid-June, an angler reported a sighting of curly pondweed at the reservoir south of the Anvil Draw boat launch. Subsequently, the same angler, while fishing from a boat, found another clump of curly pondweed floating in the south end of Big Bend. Upon investigation, more curly pondweed was found north of Brinegars Ferry boat launch, as well as mudsnails.

    “We’re disappointed to verify the presence of curly pondweed and mudsnails in Flaming Gorge,” said Robb Keith, Green River regional fisheries supervisor. “This discovery exemplifies the need for diligence from all watercraft users to stop at AIS check stations and follow Clean, Drain and Dry procedures to keep all AIS 一 even those already found in Wyoming 一 from spreading.”


    Although historical records show curly pondweed was detected in Flaming Gorge Reservoir in 1979 and 1980, subsequent surveys had not detected the plant until now. Keith said he is grateful to the members of the public for reporting their sightings. 

    “Thank you for any and all reports of AIS sightings. These tips are crucial to our AIS response. Because of this information, we are able to act quickly to verify the presence of AIS to contain the spread,” Keith said.

    At this time, there are no changes for boaters or other water users. To help limit the spread of these aquatic invasive species, the Game and Fish asks recreationists to Clean, Drain and Dry their watercraft after every use and to take an extra minute to ensure they are not transporting any vegetation or debris on their watercraft, equipment or trailers. Boaters are reminded that Game and Fish regulations require the immediate removal of all visible vegetation from watercraft and trailers when leaving waters of this state.

    Curly pondweed is native to Eurasia, Africa and Australia and was introduced into the United States in the mid-1800s. It is now found throughout the continental U.S. In Wyoming, curly pondweed has been found in Boysen, Deaver, and Keyhole reservoirs, Lake DeSmet, Wheatland Reservoir #3, West Newton Lake and in the Miracle Mile (North Platte River between Kortes and Pathfinder reservoirs). 


    Curly pondweed reproduces by seed or leaf fragments, which can be easily transported in mud or water and has the potential to form dense mats of vegetation, negatively impacting water-based recreation. It is typically introduced into new areas accidentally and as an ornamental plant.

    New Zealand mudsnails are native to New Zealand and surrounding islands as the name suggests. First discovered in Idaho in the Snake River in 1987, they have spread to other western states, including Wyoming, where they are found in Lake Cameahwait, and the Bighorn, Shoshone, Snake, Salt and North Platte rivers. 

    “Because they reproduce asexually, these snails can be easily spread and produce a new population,” said Eric Hansen, Green River AIS specialist. “They seal themselves off allowing them to survive for extended periods of time out of water, or even through the digestive system of birds and fish.” 


    Game and Fish will continue to monitor these occurrences and determine how widespread the populations of these AIS are within Flaming Gorge Reservoir and surrounding areas. 


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