Yellowstone National Park--Exotic Threats

Yellowstone National Park Fishing Regulations
General Regulations
Area Specific Regulations
Species Regulations
Exotic Threats
Advice to Anglers

Exotic Threats to
Yellowstone Fisheries

Yellowstone fisheries are threatened by two potentially damaging exotic organisms. Whirling Disease has been implicated in the decline of wild trout in the Madison River outside of the park. The New Zealand Mud Snail, which occurs in the Firehole and the Madison Rivers, may harm aquatic insect communities. Please help prevent further spread of these invaders by thoroughly cleaning mud, plants, and debris from your fishing equipment, and inspecting footwear before leaving your angling site. Drain livewells and only clean fish in the same body of water in which they were caught. Report sightings of the tiny (less than 1/4 inch) black snails to a park ranger.