Yellowstone Forever

May 27, 2009

Hitchhikers Threaten Yellowstone Ecosystem

There are hidden dangers lurking beneath the surface of Yellowstone’s waters.  At serious risk are essential food sources for native cutthroat trout, as well as the eagles, ospreys, pelicans, otters, and grizzly bears that rely on trout as prey.  Non-native aquatic species of snails, mussels, algae, and disease are rapidly spreading in western U.S. streams and lakes, and threatening waterways in Yellowstone.  But visitors like you can help stop these aquatic "hitchhikers.”

Big Dangers in Small Packages

Typically introduced from other continents, aquatic invasive species lack predators which would keep their populations in check.  The organisms compete with and displace native species, thereby harming the native ecosystem. 

Boat on Yellowstone LakeFor example, just one female New Zealand mud snail, which is self-cloning, can spread the species into new waterways.  It competes with native insects such as mayflies and stone flies, which are primary food sources for native cutthroat trout, and thus impacts birds, bears, and other species in the food chain. Already, the New Zealand mud snail and whirling disease have negatively impacted Yellowstone’s native fish.

Because aquatic invaders are usually small and live beneath the water's surface, their presence may go sight unseen until it is too late, and their damage is costly and irreversible. 

In general, aquatic invaders are transported from one place to another by humans.  While fishing and boating are the cause of much of this transport, any recreational activities in the water can pick up aquatic hitchhikers, including snorkeling, windsurfing, river floating, and even swimming.

Since Yellowstone is an international destination for recreational boating and fishing, the potential for spreading aquatic invaders is high. Last year alone, boaters from 43 States arrived in Yellowstone, many from waters contaminated with unwanted hitchhikers such as zebra mussels, didymo (“rock snot”), New Zealand mud snails, and whirling disease.

The Good News

Angler in meadowDespite the significant threat to Yellowstone, the good news is that the spread of these harmful aquatic invaders can be prevented.  The proper cleaning of boats and equipment has proven a simple yet effective way to halt the “hitchhiking” ability of these aquatic invasive species.

“Prevention is, by far, the best strategy for protecting Yellowstone’s premier aquatic resources,” said Dan Reinhart, Supervisory Resource Manager for Yellowstone.  “While some of the Park’s waterways have been contaminated, many others remain free of these invaders.  These relatively pristine ecosystems require protection now, before it is too late,” said Reinhart.

Taking Action in Yellowstone

Starting in 2006, Yellowstone National Park implemented an education and prevention program to protect Yellowstone’s waters from aquatic hitchhikers.  The pilot program has proven successful in raising public awareness about prevention measures.

Boat Launch with PosterEach summer, thousands of visitors are contacted, and hundreds of boats and pieces of angling equipment are inspected. Word is spread through brochures distributed to the public, and  posters displayed at key boat launches and trailheads. A mobile wash station mounted on a trailer is deployed to decontaminate boats and equipment.

The Yellowstone Park Foundation has funded the Stop Aquatic Invaders! program for the past several years in Yellowstone and surrounding public lands.

Funding is being used for the cleaning equipment, educational materials, and project staffing at Yellowstone Lake, including volunteers and interns to help inspect boats and gear and raise public awareness.

According to Dan Reinhart, there is great value in implementing preventative measures now -- and outside the immediate boundaries of Yellowstone -- rather than spending greater time, effort, and expense later to try to remove established invaders. 

“Well-known aquatic invaders such as whirling disease and New Zealand mud snail have acquired a strong foothold in the Park,” said Reinhart. “The costs of controlling and trying to remove these species can been staggering.”

Since 2006, many of the program’s messages have been integrated into existing Park and other public land outreach activities, and awareness about preventing aquatic invaders is gradually growing among area staff and visitors.

How You Can Help

There are several ways you can help Yellowstone with this important effort when you visit the park.

Power washing a boatLearn More.  You can find out about the different types of aquatic invasive species threatening Yellowstone, their potentially damaging effects, and how you can help prevent their spread.

Practice simple procedures.  Always follow these procedures when fishing, boating, or taking part in any recreational activities in the water:


  • Remove any visible mud, plants, fish or animals before transporting boats or other equipment.
  • Eliminate excess water that may have accumulated inside equipment before transporting.
  • Clean and dry anything that came in contact with water -- this even includes clothing and dogs!
  • Never release plants, fish, or animals into a body of water unless they came out of that body of water.


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