Invasive Threats to Black Canyon Fisheries

The aquatic ecosystems of Black Canyon are threatened by many potentially damaging exotic organisms. The National Park Service is serious about preventing the invasion of exotic species, and asks for your help in keeping the Gunnison River clean, clear, and fishable.

New Zealand mudsnail

USGS Photo

The New Zealand mudsnail occurs in Colorado but is currently not at Black Canyon. If the snail were to become introduced to the Gunnison River, the fishery could be devastated. New Zealand mudsnails can harm aquatic insect communities, impacting the food chain, and can change the physical characteristics of the river by quickly reproducing in high density masses.

There is no environmentally sound or inexpensive way to eliminate New Zealand mudsnails once they are introduced.

Please help prevent further spread of these invaders:

New Zealand mudsnail size comparison

USGS Photo

  • CLEAN and INSPECT - Thoroughly rinse and inspect all gear and boating equipment before you leave/enter an area. Clean gear of all material coming from the water (ex: scrub soles of boots, rinse waders, drain cooling and livewell water away from shore) and inspect hard- to-clean areas like laces, insoles, etc.
  • DRY - Completely dry all gear and boating equipment for 48 hours before using in a different area. Multiple sets of gear are recommended for frequent travelers visiting many areas.
  • FREEZE, SOAK, or SPRAY - Alternative cleaning methods include freezing gear overnight, soaking gear in hot water for 5 minutes (120°F; warning, may damage Gortex®), and applying Formula 409® (50% dilution recommended) for 5 minutes (soak or shake in waterproof gear bag). Dispose of all chemicals and rinse water properly.
  • REMEMBER - Mud, sand, plant fragments, and gravel on your gear are all signs that mudsnails may be hiding in your equipment (boots, nets, boats, trailers, etc.).

It is a state and federal offense to transport or release New Zealand mudsnails.

Please report any sightings of New Zealand mudsnails to a park ranger.

Additional Information:

Colorado Division of Wildlife

Whirling Disease is a parasitic infection affecting primarily rainbow and cutthroat trout populations. The Gunnison River is already positive for this parasite, however, detailed information about this disease and its prevention and control is available from the Colorado Division of Wildlife.

Last updated: March 31, 2012

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Mailing Address:

102 Elk Creek
Gunnison, CO 81230


(970) 641-2337 x205

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