Aquatic Invasive Species (AIS)

An aquatic invasive species is as a waterborne, non-native organism that threatens the diversity or abundance of native species, the ecological stability of native waters or threatens a commercial, agricultural, aquacultural or recreational activity. Increasingly, we live in a world of aquatic invasive species.  From weeds to fish, we intentionally and unintentionally move species around at an amazing pace, often with disastrous results to our native species.  In some states, such as Arizona, there are more introduced non-native fish species than native ones, and introduced species have caused widespread loss of fish populations across the country.  Introduced brook trout displace threatened native greenback cutthroat trout in Colorado's Rocky Mountains, but in their native range, brook trout themselves often are displaced by brown and rainbow trout.  In Yellowstone Lake, introduced lake trout and whirling disease have combined to cause a nearly 90% decline in the lake’s Yellowstone cutthroat trout population.  Introduction of aquatic invasive species ranks second only to loss of habitat as the primary threat facing our fish, wildlife and plants and pose a serious threat to TU’s mission to conserve North America’s cold water fisheries. 

Aquatic invasive species make their way into our lakes and streams by many means.  Some species are intentionally introduced as sport or forage species while others are illegal releases by “bucket biologists” who selfishly want their favorite fish to be available in their home waters.  Some species are released unintentionally or escape from aquaculture facilities, and still others stow away in ship ballast water only to be released thousands of miles from their native habitat.  Exotic diseases and parasites such as Viral Hemorrhagic Septicemia and Whirling Disease may accompany the introduced fish and spread to native species. Anglers can do their part to lower the risk of spreading aquatic invasive species. Carefully clean and dry all equipment afar use to avoid contaminating clean waters.  See our guide to equipment disinfection methods for guidelines and sign the clean angling pledge.

Find out more about specific invasive species

• Non-native Fishes:  Rudd, Snakeheads
• Invertebrates: New Zealand Mudsnail, Zebra Mussels
• Pathogens:  Whirling Disease
• Plants:  Eurasian Water-Millfoil, Didymo