Greater Yellowstone
Coordinating Committee

Threat to the Ecosystem

Aquatic invasive species (AIS) threaten to fundamentally alter aquatic ecosystems and put the native plants and animals of the GYE at risk. AIS are organisms or pathogens that are introduced to an ecosystem outside their historical natural range. They frequently cause irreversible ecological and economic damage or harm to human health. Eliminating AIS after they become established is usually impossible, and efforts to reduce their impact can be extremely expensive. Preventing new introductions and the spread of existing AIS is a fiscally responsible and ecologically important task that requires a focused, coordinated effort among all parties within the GYE, whether governmental, nonprofit, or private.

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Status and Trends in Greater Yellowstone

In addition to nonnative fish in the GYE, these AIS are already having a detrimental effect:
• Myxobolus cerebralis causes whirling disease in cutthroat trout and other species.
• New Zealand mud snails (Potamopyrgus antipodarum) form dense colonies and compete with native species.
• Red-rimmed melania (Melanoides tuberculatus) out-compete native snails.
• American bullfrogs, big-ear radix, red-eared sliders, Eurasian watermilfoil, and curly-leaf pondweed are
also in the GYE.

Numerous species of AIS are expanding in their ranges and pose a tremendous risk to GYE ecological, recreational, and economic values. These AIS include quagga and zebra mussels, Asian clams, Asian carp species, Eurasian watermilfoil, hydrilla, flowering rush, and viral hemorrhagic septicemia. Quagga and zebra mussels, two of the most feared AIS in the U.S., have continued to expand their distribution since they were introduced to the Great Lakes in the 1980s. In 2022, zebra mussels were documented in western South Dakota and central Colorado, less than 400–500 miles from the GYE. In 2023, quagga mussels were confirmed in the Snake River near Twin Falls, Idaho, less than 300 miles from the GYE.

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Publications/Products Produced:

• AIS Pocket Guide for the Greater Yellowstone Ecosystem (3 MB pdf)

• GYA Aquatic Invasive Species Cooperative Strategic Plan, 2016 (53 kB pdf)

• GYA Aquatic Invasive Species Cooperative Strategic Plan, 2009 (65 kB pdf)

• GYA Aquatic Invasive Species Cooperative Implementation Plan, 2009 (384 kB pdf)

• GYA Aquatic Invasive Species Cooperative 2009 Accomplishment Report (171 kB pdf)

• GYCC Risk Analyzer (Adam Sepulveda, USGS, Josh Gage, Gage Cartographics)

  • Online Risk Analyzer Tool

  • Users Guide (976 kB pdf)​