Aquatic Invasive Species (AIS)
Most Yukon lakes and waterways appear to remain free of aquatic invasive species. That makes prevention especially important.
Aquatic invasive species are non-native plants, animals, diseases or other organisms that can spread through water and cause harm. Many can travel unnoticed on boats, trailers, fishing equipment, footwear, mud or trapped water.
How aquatic invasives spread
Boats and fishing equipment are among the pathways people can most easily control. Plants, animals, microscopic organisms, mud and water can travel on or inside boats, trailers, motors, bilges, live wells, paddles, waders, nets and other gear.
Aquarium species, pond plants, bait and fish can also become invasive when people release or move them into new waters.
Our watchlist
Zebra and quagga mussels
Dreissena polymorpha and Dreissena rostriformis bugensis
Status: Prevention priority, not known to be established in Yukon
These small freshwater mussels can attach in large numbers to boats, docks and water infrastructure and change aquatic food webs. Adults can hitchhike on watercraft and equipment, while microscopic larvae can travel in standing water.
Keeping them out of Yukon is much easier than managing them after establishment.
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New Zealand mud snail
Potamopyrgus antipodarum
Status: Prevention priority, not known to be established in Yukon
This tiny freshwater snail can be difficult to notice and can travel in damp mud on waders, boots, nets and other equipment. Yukon research has identified it as one of the aquatic invasive species of greatest management concern for the territory.
Eurasian watermilfoil
Myriophyllum spicatum
Status: Prevention priority, not known to be established in Yukon
Eurasian watermilfoil is an invasive aquatic plant that can spread from small fragments caught on boats, trailers and fishing equipment. Dense growth can displace native aquatic vegetation and interfere with recreation.
Yukon has native aquatic plants that may look similar, so photograph and report suspicious plants rather than trying to identify them from appearance alone.
Whirling disease
Caused by Myxobolus cerebralis
Status: Prevention priority, Yukon currently designated free of the disease
Whirling disease is caused by a microscopic parasite that affects trout, salmon and whitefish. It can be spread through infected fish and contaminated mud, water or equipment.
As of May 2026, Yukon waters are designated by the Canadian Food Inspection Agency as free areas for whirling disease.
Didymo
Didymosphenia geminata
Status: Present in Yukon, may be native
Didymo is an algae that can form thick brown, tan or whitish mats on streambeds. It occurs in Yukon, but Government of Yukon notes that it may be native here, so it should not be treated in the same way as a confirmed introduced invader.
Regardless of its origin, cleaning fishing and boating equipment helps prevent organisms from being moved between waterways.
What you can do
1
Clean plants, animals, mud and other debris from boats, trailers and equipment.
2
Drain all water before leaving the water access.
3
Dry your boat and equipment completely before entering another waterbody.
4
Don't Let It Loose. Never release aquarium animals, pond plants, bait or aquarium water into the environment.
5
Never move live aquatic organisms between Yukon waters unless specifically authorized.
See something unusual?
Early detection gives us the best opportunity to respond before a new aquatic invasive species spreads.
Take a clear photo, record the exact location and avoid moving the organism to another waterbody. Report suspected aquatic invasive species to the Government of Yukon Fisheries Unit using the current contact information on its aquatic invasive species webpage.
And before visiting another lake or river: Clean, Drain, Dry.
Sources
Information on this page was reviewed in September 2026 using current Yukon and Canadian sources, including, but not limited to:
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Government of Yukon — Aquatic Invasive Species: The primary source for Yukon-specific prevention and reporting guidance, including Clean, Drain, Dry practices and how to report a suspected aquatic invasive species.
Government of Yukon aquatic invasive species guidance
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Government of Yukon — Framework for the Management of Aquatic Invasive Species in Yukon: Used for Yukon-specific information on priority aquatic threats, introduction pathways, risk and prevention. This assessment was produced in 2016, so older species-status information was checked against newer territorial and federal sources.
Yukon aquatic invasive species framework
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Government of Yukon — State of the Environment Reports: Used to check current information on introduced and invasive species in the territory. The most recent report available during this review was the 2025 interim report.
Yukon State of the Environment reports
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Fisheries and Oceans Canada: Used to confirm current Canadian aquatic invasive species prevention guidance, including cleaning, draining and drying watercraft and equipment and avoiding the release of aquatic organisms.
Fisheries and Oceans Canada aquatic invasive species information
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Canadian Food Inspection Agency — Whirling Disease: Used for current information on whirling disease, its transmission and its status in Canada. The federal information was last updated in May 2026.
CFIA whirling disease information
Aquatic invasive species distributions can change quickly. YISC will update this page as new Yukon detections, risk assessments or official guidance become available.