Aquatic Invasive Species

Aquatic invasive species (AIS) are a serious threat to Door County’s waterways and wetlands.  Whether they are moved in ballast water, recreational boats, or in the water of a livewell or bait bucket, many non-native animals such as the spiny waterflea continue to spread throughout Wisconsin and the Midwest.  These animals can cause severe damage to local ecosystems, industry and  tourism.  In addition, invasive aquatic plants are one of the greatest threats to the long-term health of our wetlands.  Reed canary grass currently dominates almost half a million of Wisconsin’s wetland acres and Phragmites has been expanding westward through Wisconsin from the Lake Michigan shoreline.  DCIST has created the following list of aquatic plants and animals that threaten Door County’s natural environments and economy.  A summary of the “Top 15” Invasive Plants in Door County (with pictures) can be found at the bottom of this page.   


You can help prevent the spread of AIS in our waters and wetlands by doing the following:  

  • INSPECT boats, trailers and equipment  
  • REMOVE any attached aquatic plants or animals before and after each use 
  • DRAIN all water from boats, motors, and equipment 
  • NEVER MOVE live fish away from a waterbody 
  • Know the bait laws and DISPOSE of unwanted bait in the trash. 
  • If possible, DECONTAMINATE equipment (e.g. boat washing station)

    For more steps to slow the spread of invasive species, visit the Wisconsin DNR’s Prevention Page.

Aquatic & Wetland Invasive Species to Know

Eurasian Water-Milfoil

Eurasian Water-Milfoil - Paul Skawinski, UW-Extension Lakes

Myriophyllum spicatum
View More Photos - Explore Facts
Learn How to Control

Photo: Paul Skawinski, UW-Extension Lakes

Curly-Leaved Pondweed

Curly-leaved Pondweed; Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Potamogeton crispus
View More Photos - Explore Facts
Learn How to Control
Photo: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Starry Stonewort

Starry Stonewort; Paul Skawinski, UW-Extension Lakes

Nitellopsis obtusa

View More Photos - Explore Facts
Photo: Paul Skawinski, UW-Extension Lakes

Round Goby

Round Goby - Paul Skawinski, UW-Extension Lakes

Neogobius melanostomus
View More Photos - Explore Facts
Prevent their Spread

Photo: Paul Skawinski, UW-Extension Lakes

Rusty Crayfish

Rusty Crayfish; U.S. Geological Survey , U.S. Geological Survey, Bugwood.org

Orconectes rusticus

View More Photos - Explore Facts

Prevent their Spread
Photo: U.S. Geological Survey , U.S. Geological Survey, Bugwood.org

Bighead & Silver Carp

Silver Carp; Lindsey Lewis, U.S. Fish and Wildlife, Bugwood.org

Hypophthalmichthys nobilis and H. molitrix

View Bighead Photos - View Silver Photos

Explore Facts - Prevent their Spread

Photo: Lindsey Lewis, U.S. Fish and Wildlife, Bugwood.org

Zebra Mussels

Dreissena polymorpha

View More Photos - Explore Facts 

Prevent their Spread

Photo: Randy Westbrooks, Invasive Plant Control, Inc., Bugwood.org

Quagga Mussels

Dreissena bugensis

View More Photos - Explore Facts 

Prevent their Spread

Photo: Mike Quigley, NOAA, Bugwood.org

White Perch

Nate Tessler, EnviroScience, Inc., Bugwood.org

Morone americana

View More Photos - Explore Facts 

Prevent their Spread

Photo: Nate Tessler, EnviroScience, Inc., Bugwood.org


Spiny & Fishhook Waterfleas

Gary Montz, 144, Bugwood.org

Bythotrephes cederstroemi &
Cercopagis pengoi

View More Photos - Spiny Facts

Fishhook Facts - Prevent their Spread

cPhoto: Gary Montz, 144, Bugwood.org

Common Reed (Phragmites)

Photo: Paul Skawinski, UW-Extension Lakes

Phragmites australis

View More Photos - Facts & Identification
Control Guide
Photo: Paul Skawinski, UW-Extension Lakes

European Marsh Thistle

Cirsium palustre

View More Photos - Explore Facts

Control Recommendations

Photo: Kari Hagenow, The Nature Conservancy

Japanese Knotweed

Polygonum cuspidatum
View More Photos - Explore Facts
Control Recommendations - More Control
Photo: Kari Hagenow, The Nature Conservancy

Purple Loosestrife

Lythrum salicaria
View More Photos - Explore Facts
Control Recommendations

Photo: Paul Skawinski, UW-Extension Lakes  

Reed Canary Grass

Phalaris arundinacea
View More Photos - Explore Facts
Control Recommendations
Photo: Kari Hagenow, The Nature Conservancy

Narrow-Leaved Cattail

Typha angustifolia
View More Photos - Explore Facts
Control Recommendations
Photo: Mandy Tu, The Nature Conservancy, Bugwood.org

Flowering Rush

Butomus umbellatus
View More Photos - Explore Facts
Control Recommendations
Photo: Leslie J. Mehrhoff, University of Connecticut, Bugwood.org

Yellow Water-Flag Iris

Iris pseudacorus

View More Photos - Explore Facts
Control Recommendations
Photo: John M. Randall, The Nature Conservancy, Bugwood.org

Lyme Grass

Leymus arenarius
View More Photos - Explore Facts
Control Recommendations
Photo: Nisa Karimi, Wisconsin Department of Natural Resources, Bugwood.org

Canada Thistle

Cirsium arvense
View More Photos - Identification Video
Explore Facts
Control Recommendations
Photo: Jan Samanek, Phytosanitary Administration, Bugwood.org

Glossy Buckthorn

Frangula alnus
View More Photos - Explore Facts
Control Recommendations

Photo: Rob Routledge, Sault College, Bugwood.org