Aquatic Invasive Species



Forest Aquatic Invasive Species Program

Aquatic invasive species can threaten the water resources on the Shoshone National Forest. We rely on the careful actions of visitors to keep these invaders out of our waters.

Wyoming is home to many great streams, rivers, and lakes, and over 1 million people visit annually, many for the fishing and boating opportunities. Aquatic hitchhikers can come along for the ride and harm the very systems we so value. The Shoshone National Forest, in cooperation with the Wyoming Game and Fish Department and Wyoming State Parks, is spreading the word on aquatic invasive species, what they are, what they can do, and how to prevent them. The Clean Inspect Dry program will let you know what you can do to help prevent the spread of aquatic invasive species. 

What Can You Do?

Boaters should get the aquatic invasive species sticker for your boat before you launch. The sticker program helps fund boat inspection stations to keep invading species out of our lakes. Make sure you stop if you pass an inspection station, and seek one out if you are coming from a state with quagga or zebra mussels.  Everybody should Clean, Inspect, and Dry your fishing, boating, and other water gear.  Hitching a ride on dirty water gear is the primary way aquatic invasives travel, so make sure you scrub the mud from all those nooks and crannies on your wading boots and that you drain out your live wells and bilges before leaving the lake.  If you see anything suspicious, put it in some water and bring it to your nearest Game and Fish or Forest Service office.  We are counting on you to inspect your gear, clean it before you move to a new water body, and dry it thoroughly whenever you get the chance.  Thank you so much for helping us keep the Shoshone National Forest a healthy place for fish and other aquatic critters!

Zebra and Quagga Mussels

Both are generally small (thumbnail-sized) and attach to nearly any surface via hair-like structures.  Zebra mussels are triangular with a flat ventral side and distinct striping pattern. Quagga mussels are rounder with dark rings that lighten toward the hinge.
Spread:  Originally carried from Europe in ships’ ballast water, these mussels have moved from the Great Lakes attached to the surface of boats or carried in pockets of trapped water. They have been found in the Rocky Mountain West, but not in Wyoming, and your efforts can help keep it that way.
Impacts:  Zebra and quagga mussels can quickly colonize any surface, in some cases forming a carpet that clogs pipes and boat motors, outcompetes native mussels, and changes the aquatic food chain, impacting local fisheries.

New Zealand Mudsnails

These snails are very small (1/5 inch) with conical shells and 5-6 right-leaning whorls.
Spread:  Native to New Zealand, these snails were first found in the Snake River in Idaho in the late 1980s.  They have since established in the Firehole River and several other waterways including, most recently, the Shoshone River downstream from Cody.  Mudsnails can be spread on unwashed boats and fishing gear and can survive the digestive systems of fish, so dispose of the remains of harvested fish carefully.
Impacts:  Reproduces quickly and can reach very high densities, crowding out native invertebrates and altering the aquatic food chain.

Whirling Disease

ID:  Whirling disease is the result of a parasite that impacts trout and other salmonids. It is identifiable by characteristic skeletal changes in young fish leading to awkward swimming, frenzied tail chasing, and, eventually, death.
Spread:  The parasite originated in Europe, where native trout have developed resistance.  The disease is spread by waterborne spores which can easily attach to fishing gear and survive for decades in storage. 
Impacts:  The primary impact of whirling disease is the direct mortality it causes in primarily spring spawning trout populations.

Didymo (Rock Snot)

This diatom can produce thick mats along stream and lake beds.  These mats appear slimy but feel like wet wool to the touch.
Spread:  Although native to the Greater Yellowstone Area at higher elevations, didymo has expanded its range with increasing incidences of nuisance outbreaks.  It can be easily spread by fishing gear or waders that have not been cleaned.
Impact:  Large nuisance mats can choke out most other aquatic life, including fish.  Didymo mats can cover more than half a mile of stream, and last for months.