Aquatic Invasive Species

Aquatic invasive species are a growing risk for National Park resources and values. In the United States there are more than 250 non-native aquatic species from other continents and over 450 non-natives within North America that have been moved outside their native habitats!

Aquatic invasive species pose threats to parks, ecosystems, and visitors by:

  1. Outcompeting native species
  2. Threatening the safety of park employees and visitors
  3. Changing and degrading the experience of park visitors
  4. Requiring intensified maintenance and monitoring
  5. Altering natural ecological processes

NPS Most Wanted Aquatic Invaders

Highlighted invasive species of concern

There are many aquatic invasive species within National Parks. Learn about a few that are especially aggresive below.
rusty crayfish
Rusty Crayfish can out-compete native crayfish and can reduce some fish populations.

Missouri Department of Conservation


Rusty Crayfish and Virile Crayfish are native to North America; however, when these species are introduced outside of their native ranges, they can become extremely problematic for National Parks.

Rusty crayfish (pictured left) are invasive everywhere outside of their native southern U.S. ranges. Virile Crayfish, are invasive everywhere but Missouri, lower Ohio, upper Mississipi, and Great Lakes drainages (FWS, 2015).

Bait buckets are known to be a major pathway for the introduction of crayfish and other invasive species. If possible, avoid the use of live bait OR dispose live bait into trash cans.

Photo of quagga mussels
It is important to clean, drain, and dry your boat to prevent the spread of quagga and zebra mussels.

NPS Photo

Quagga and Zebra Mussels

Quagga and zebra mussels are small freshwater mollusks with zebra-like patterns on their shells. Both species were introduced to the Great Lakes in 1986 and quickly spread to many waters east of the Mississippi River. In 2007, Lake Mead National Recreation Area became the first water body west of the Rocky Mountains to identify an established population of quagga mussels.

Both mussels remove filter plankton from water, which can alter aquatic ecosystems and have devastating effects on native species. Thousands of larvae can be found in a single teaspoon of water, making it easy to transport these aquatic hitchhikers. Once established, both mussels are typically expensive to control and impossible to eradicate.

Lionfish swimming along coral reef.
Lionfish are prolific throughout the Southeastern United States, Gulf of Mexico, and Caribbean.

NPS Photo/ Cliff M.


Lionfish are native in the Pacific and Indian Oceans; however, are invasive in the Atlantic Ocean. Lionfish were first detected off the coast of Florida in 1980s, and have since spread along the Atlantic coast of the United States and throughout the Gulf of Mexico and Caribbean. These venomous fish cause ecologic harm to coral reefs, and can risk visitor safety because of their venomous spines.

The National Park Service manages this invasive species by removing it from the affected waters in order to improve visitor safety and allow the ecosystem to recover.

Removal and Prevention

Most often, removal of aquatic invasive species is difficult and expensive to do. For example, once a population of zebra mussels is establised, eradication is impossible.

Prevention is the best way to stop aquaitc invasive species. This means that you can help the National Park Service by fishing and recreating responsibly. Make sure to clean, drain, and dry your boat and fishing gear. Although using live bait is sometimes necessary (and legal), dispose of unwanted live bait into trash cans and NEVER into waterways. Learn more tips on What You Can Do to prevent invasive species and watch the video below to learn more about clean, drain, dry.

Aquatic Invasive Species

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    Last updated: February 28, 2018