Aquatic invasive species

  • What are aquatic invasive species?
  • Help stop aquatic invasive species
  • ​Report aquatic invasive species

  1. What are aquatic invasive species?

    Aquatic invasive species can harm native species by bringing disease and altering natural ecosystems. This can have a negative effect on fisheries, tourism, health and recreation. The Yukon Invasive Species Council defines an invasive species as:

    "An organism (plant, fungus, or bacterium) that is introduced into an ecosystem and has negative effects on the economy, environment, and/or health. The term “invasive” is reserved for the most aggressive species, which reproduce rapidly and cause major changes to the areas where they become established."

    How are aquatic invasive species spread?

    People spread aquatic invasive species when they:

    • dump their aquariums illegally; and
    • move from place to place. Aquatic organisms can cling to boats, fishing gear and footwear and unknowingly be transported from one area to another.

    Are there aquatic invasive species in the Yukon?

    • Most Yukon lakes and waterways appear to be free of invasive species.
    • Some species of fish have been introduced to Yukon waters but are not considered invasive. These include rainbow trout, stickleback, Arctic char and goldfish.

    What aquatic invasive species should I be aware of?

    Zebra and quagga mussels

    Zebra mussels and quagga mussels attach to boat hulls and underwater infrastructure and can cost millions of dollars in damage. Adult mussels can live several weeks out of the water and be transferred from one body of water to another.

    Identify zebra and quagga mussels

    Zebra and quagga mussels:

    • are small and only up to 3 cm;
    • are shaped like propeller blades;
    • have yellow or brownish shells;
    • can have light-coloured zebra stripes; and
    • form dense clumps and firmly attach themselves to solid objects.

    Didymo algae

    Didymo algae is found in the Yukon. It is considered an invasive species in other parts of Canada, but may be native to the Yukon. Further research will provide us with an answer.

    This algae can form large, slippery mats that cover stream beds. These mats can damage organisms in Yukon waters and degrade fisheries by changing the natural ecosystem and disrupting fish rearing habitat. As stream levels drop, didymo mats resemble and are mistaken for toilet paper.

    This YouTube video produced by New Zealand Fish and Game explains how didymo can form large algal blooms.

    Identify didymo algae


    • is brownish-yellow to white and form in clumps or ropes. It isn't didymo if it is green or dark brown or black or transparent;
    • has a rough texture like wet cotton wool when pulled apart. It isn't didymo if it has a slimy texture or falls apart when handled; and
    • is found in clumps on rocks or plants, or floating in the current. It isn't didymo if it is attached to the bottom with roots.

    Find out more about aquatic invasive species in the Yukon

    Reports on Yukon aquatic invasive species

  2. Help stop aquatic invasive species

    One of the most important things you can do to stop aquatic invasive species is to not move water, fish, plants or aquatic life from one water body to another. If you boat, fish or use Yukon waters you should follow the Clean, Drain, Dry guidelines to stop aquatic invasive species.

    Note: It’s illegal to bring live water creatures into Yukon waters or to transfer them among bodies of water without a permit. This includes live fish, uncured fish eggs, crayfish, leeches and water plants.

    Clean, Drain, Dry guidelines

    Clean mud, weeds and aquatic life from equipment before leaving the area

    Mud and weeds can keep invasive species cool and moist, allowing them survive a long time.

    Drain water from bilges, pumps, coolers and buckets before leaving the area

    Draining water makes it harder for aquatic invaders to survive and be transferred to new waters.

    Dry boat and gear

    Dry your boat and equipment before heading to another body of water. It can take 5 days in the sun to dry. If your equipment won't dry before you head onto another body of water, you should:

    • power wash your boat and trailer;
    • freeze small items like footwear, waders and reels in a bag overnight until solid; or
    • soak gear in very hot water for 30 minutes.

    Choose your gear wisely

    • Studded or soft rubber waders are the best choice. Felt and other porous boot soles can trap moisture and spread aquatic invaders.
    • Didymo algae, also known as "rock snot" can live several weeks when attached to felt soles.
    • If you have felt-soled waders, it's best to freeze them solid overnight.

    Report an aquatic invasive species

    Help stop the spread of aquatic invasive species by reporting them when you spot them. If you think you've spotted an aquatic invader email or phone 1-800-661-0408, ext. 5721.

    See the next section for more details.

  3. ​Report aquatic invasive species

    If you think you've spotted an aquatic invader:

    1. Report the incident to the Fisheries Unit by calling 1-800-661-0408, ext. 5721 or emailing
    2. If possible, take a photograph and a small sample for identification in a secure plastic bag, and note the exact location.
    3. Prevent its spread with Clean, Drain, Dry.
    4. If you find a potential invasive species on equipment after leaving a site, throw it in the garbage and not down the drain.


If you have further questions about aquatic invasive species in the Yukon, email or phone: 867-667-5721, toll free in the Yukon: 1-800-661-0408 ext. 5721.