California Agency Finds Invasive Mudsnails in Feather River

CDFW biologists are conducting additional sampling in adjacent water bodies around and connected to the Feather River, including Lake Oroville, its Forebay and Afterbay, and the Yuba River to get a better idea of the geographic range of this new population.

The California Department of Fish and Wildlife announced Feb. 12 that it has confirmed the presence of New Zealand mudsnails in the low-flow section of the Feather River in Butte County. The agency is asking recreational users of the river to clean, drain, and dry their fishing and recreational gear and watercraft to help prevent the spread of the invasive snails, which reach an average length of 4-6 millimeters. "Dense populations of New Zealand mudsnails can displace and outcompete native species, sometimes by consuming up to half the food resources in the waterway. The snails have been linked to reduced populations of aquatic insects, including mayflies, caddisflies, chironomids, and other insects upon which trout and salmon populations depend," according to CDFW.

The agency has issue a directive for all equipment used in the river:

  • If you wade, freeze waders and other gear overnight (at least six hours).
  • After leaving the water, inspect waders, boots, float tubes, boats and trailers, or any gear used in the water. Remove any visible snails with a stiff brush and follow with rinsing. If possible, freeze or completely dry out any wet gear.
  • Never transport live fish or other aquatic plants or animals from one water to another.

CDFW biologists are conducting additional sampling in adjacent water bodies around and connected to the Feather River, including Lake Oroville, its Forebay and Afterbay, and the Yuba River to get a better idea of the geographic range of this new population. The target sampling areas will include high-traffic areas, boat launches, access points, and side channels.

"To date, the snails have not been identified at the Feather River Hatchery, but CDFW is setting up decontamination procedures for the hatchery as a precaution. Decontamination procedures are currently being implemented by field crews working on the Feather River and surrounding water bodies," according to the agency's release.

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