Sacramento, California - The California Department of Fish and Wildlife (CDFW) has confirmed the presence of New Zealand mudsnails in the low-flow section of the Feather River in Butte County, and is asking recreational users of the river to “clean, drain and dry” fishing and recreational gear and watercraft in order to help prevent the spread of these invasive snails.

New Zealand mudsnails are tiny, aquatic snails that reach, on average, up to 4-6 millimeters long. 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.

Boaters, anglers and others who may visit the Feather River are asked to decontaminate equipment and follow the “clean, drain and dry” directive with 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 in the process of conducting additional sampling in adjacent waterbodies around and connected to the Feather River including Lake Oroville, its Forebay and Afterbay, and the Yuba River in order to better define the geographic range of this new population. 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 waterbodies.

In the coming weeks, CDFW will implement public outreach and education efforts, including information cards, brochures and signage posted within and outside of the hatchery facility, bait shops and boat launches along the Feather River and at various access points and wildlife areas.