Facts and FAQs about AIS

Riding Mountain National Park

Increased Monitoring for Zebra Mussel eDNA in Clear Lake

On January 23, 2023, Parks Canada received the results of one water sample test that indicated the presence of environmental DNA (eDNA) from zebra mussels at Boat Cove in Clear Lake at RMNP. The next day the test results were confirmed. The sample was taken on August 4, 2022. Three samples collected on August 26, 2022 returned negative results.

It is important to note that live zebra mussels have not been found in RMNP. It is possible that DNA came to Clear Lake on a boat or other source, but that no living mussel was transferred.

On February 21, 2023 Resource Conservation staff began taking water samples from Clear Lake to test for zebra mussel eDNA. Over the winter, staff will be drilling holes into the ice, collecting and filtering samples, and sending them to a laboratory for eDNA testing.

FAQs (Frequently Asked Questions)

What is eDNA?

Environmental DNA (eDNA) consists of tiny fragments of genetic material found in the environment. In a lake, eDNA can come from living or dead organisms, or be transferred by boats, water toys, or other objects. Zebra mussel DNA cannot become an adult zebra mussel.

What are zebra mussels?

Zebra mussels are small, clam-like aquatic animals native to Eastern Europe and Western Asia. They are 1-3 cm (0.4-1.2 inches) long, have triangular or “D” shaped shells, and most have light and dark brown bands on their shells.

Zebra mussels were discovered in Lake Erie in the mid-1980s. They were accidentally transferred from their native range by cargo ships. Within a decade, the mussels had spread throughout the Great Lakes and many inland water bodies in the Mississippi watershed to the Gulf of Mexico.

Since then, they have spread to hundreds of other water bodies, mainly in eastern North America.


  • Aggressively invade new areas and reproduce quickly. Females produce upwards of one million eggs per year.
  • Colonize almost any hard underwater surface, including watercraft hulls and can interfere with engine cooling systems.
  • Power plants, water treatment plants, and cottages can be negatively affected by clogged intake structures.
  • Threaten native fish and wildlife by reducing algae and food resources at the base of the food chain.
  • Costly nuisance to boaters, commercial fishers, anglers, and beach-goers. They can reduce recreational potential by littering beaches with sharp shells and producing foul odours from decaying, dead zebra mussels.
  • Adult zebra mussels can survive out of water up to 30 days depending on temperature and humidity. Zebra mussel veligers (larvae) are not visible to the naked eye and can survive in very little water.
What does a positive sample of zebra mussel eDNA mean for Clear Lake?

eDNA can serve as an early warning sign that zebra mussels are present, but it does not guarantee that there is an active population. It could take up to four years to determine whether zebra mussels have begun to colonize Clear Lake.

Does this mean there are zebra mussels in Clear Lake?

Not necessarily. It is not a guarantee that there are zebra mussels in Clear Lake. It could be “washout” DNA that was transferred from another lake.

DNA may come from a living organism, a dead organism, or an object with DNA on it. For example, DNA could have been shed by a mussel in Lake Winnipeg. Water containing that DNA may have dried on the surface of the boat. That DNA could then have been transferred to Clear Lake and ended up in a sample we took in early August 2022.


Can zebra mussel DNA turn into a live zebra mussel?

No. Zebra mussels reproduce when females release eggs that get fertilized by males. Those fertilized eggs can grow into adult zebra mussels.

How long until we know if there are actual zebra mussels in the lake?

It can take up to four years to confirm if zebra mussels have populated a body of water. An adult zebra mussel or veliger (larvae) is needed in order to confirm a population.

Aquatic Invasive Species (AIS)

What are aquatic invasive species?

Aquatic organisms that have spread outside of their natural, historic range. They can be plants, animals, fungi, or bacteria that have been introduced to a new body of water either on purpose, or accidentally. AIS are a significant threat to the ecological, cultural, and economic integrity of all aquatic ecosystems.

Why are AIS a concern?

If AIS, such as zebra mussels, enter park waters, the consequences could be extremely damaging. They can negatively affect both the environment and the economy. They reproduce quickly, have no natural predators, and outcompete native species for resources.

Our beaches could be covered in sharp shells, fish populations might decline which would impact fishing, our drinking water infrastructure might be at risk, and the costs to repair damages could be high.

How do they spread?

AIS, often referred to as aquatic hitchhikers, are commonly spread on wet items such as:
  • Watercraft (boats, canoes, kayaks, paddleboards, dinghies) and trailers
  • Inflatables (floaties, air mattresses, stand-up paddleboards)
  • Snorkeling and scuba diving gear
  • Beach toys
  • Fishing gear and bait buckets
  • Watercraft equipment (life jackets, anchors, ropes, paddles, and anything else that comes into contact with water)
What can we do to prevent the spread of AIS?

  • Bring your watercraft/equipment for an AIS inspection before you use it in Riding Mountain National Park
  • Clean, drain and dry all watercraft, fishing gear, and other water related equipment after use.
  • Do not transport any live aquatic animals/plants or water
  • Learn which AIS are of concern in Manitoba, the risks they pose, and report all sightings of AIS to Parks Canada Dispatch at 1-877-852-3100
  • Never bring or use live bait in park waters. For fishing regulations, please visit: Fishing in Riding Mountain National Park.

AIS Prevention Program and Inspections

What is the purpose of the AIS prevention program in Riding Mountain National Park?

To protect all bodies of water in RMNP from the introduction of AIS. Parks Canada strives to keep AIS out of park waters with mandatory AIS inspections and decontaminations, along with regular water monitoring and sampling. In doing so, Parks Canada is maintaining and enhancing the ecological integrity of the park.

What are visitors required to bring to the AIS inspection station?

Anything that will go in the water and holds people: motor boats, canoes, kayaks, paddleboards, and flotation devices. This also applies to all water related equipment that can also transport AIS, which includes inflatables, snorkeling/scuba diving gear, fishing gear, life jackets, paddles, beach toys, and any equipment used in the water.

What are AIS inspectors looking for?

As part of AIS inspections, Parks Canada staff look for signs of aquatic invasive species contamination on watercraft and water-related equipment, for instance:

  • Zebra mussel shells
  • Evidence of tiny, young zebra mussels, which feel like sandpaper
  • Standing water, which can contain veligers (microscopic larvae)
  • Mud or plants.

They also ask questions about where boat users have been to identify the level of risk.

Why is it important to get a watercraft inspected by an RMNP official AIS inspector?

Parks Canada staff are working closely with visitors to keep aquatic invasive species (AIS) out of park waters through watercraft inspections and strict decontamination procedures. The cooperation of watercraft operators is essential in preventing this threat to park waters. 100% compliance is necessary to ensure the ecological integrity of park waterways, as it only takes one contaminated watercraft to transport aquatic invasive species into the park.

All motorized and non-motorized watercraft and/or water-related equipment entering RMNP waters are required to undergo an inspection for aquatic invasive species. The service is free of charge and watercraft passing inspection will receive a permit from Parks Canada watercraft inspectors. This applies to all watercraft, trailers, canoes, kayaks, wind-driven vessels, stand-up paddleboards, inflatables, scuba diving gear, fishing gear, life jackets, beach toys and any other equipment used in the water.

Who issues watercraft inspection permits in Riding Mountain National Park?

Only trained Parks Canada AIS Inspectors can issue watercraft inspection permits valid for Riding Mountain National Park.

How long does an AIS inspection take?

An average of 10-30 minutes.

How long does decontamination of watercraft take?

30-90 minutes for most watercraft, and 120+ minutes for large and/or complex watercraft such as wake boats.

How can I prepare for an inspection?

Know your watercraft and equipment and where they were last used.

Inspectors will need full access to your watercraft or equipment to inspect them. For example, be prepared to take your canoe, kayak, or paddleboard off your roof rack, open up your inflatables, lower your motor, or open up watercraft compartments.

Do I need to have my watercraft re-inspected if I leave Riding Mountain National Park and launch elsewhere?

YES. Every time you launch outside of park waters, your watercraft must be re-inspected. All watercraft must also be re-inspected after their AIS inspection permit has expired.

Why have leeches been banned as bait?

Due to the increased risk of spreading AIS via natural bait, the use and possession of leeches is prohibited. Parks Canada encourages anglers to confine the use of tackle to individual lakes and to ensure that all fishing gear is clean and dry before use in park waters. Fish and fish parts are also not allowed to be used as bait in RMNP. Please see: 
pdf-icon Fishing Regulations (1.2 MB) 

More AIS of Concern in Manitoba

Spiny waterflea (Bythotrephes longimanus)


Photo: Emily DeBolt

These are tiny aquatic animals, approximately 1 cm in length. They have a long, straight tail spine that is twice as long as its body. The spines on their tails make it easy for them to attach onto fabric materials, such as life jackets, ropes, carpet on bunks or boats. They can also survive in small amounts of water.


  • Able to reproduce asexually by cloning, which means it only takes one to populate a body of water. They also reproduce sexually, and can multiply very quickly. When they reproduce sexually, the eggs can survive through the winter on lake bottoms.
  • Their eggs can survive out of water so ensuring that the watercraft and all water related equipment are completely dry for five days will reduce the risks.
  • Outcompete native species for food and habitat resources, which can reduce populations of popular angling fish species.
  • No known way to eradicate once a population has been established.
  • They can be found in Lake of the Woods, the Winnipeg River, Lake Winnipeg, the Nelson River, Shoal Lake (MB/ON border), and the Saskatchewan River (including Cedar Lake) in MB.
Rusty crayfish (Faxonius rusticus)


Photo: Doug Watkinson DFO

Have large claws with black bands near the tips and are larger in size than native crayfish. They have dark, rusty spots on each side of their brown body.


  • Aggressive eating habits – outcompete native crayfish.
  • No practical way to remove them once they’ve been established.
  • Reduce spawning habitat for native fish.
  • Females can carry up to 200 fertilized eggs under their tail – rapid spread.
  • Illegal to possess and transport ANY crayfish (native species or not).
  • They can be found in Falcon Lake, a portion of the Birch River near Prawda, the ON portion of the Winnipeg River, and Lake of the Woods in Manitoba.
Black algae

This type of algae forms dense mats and has a strong musty smell.

  • Very dark green or black in colour, and has the appearance and feel of wet wool or dog fur. 
  • Grows densely on lake bottoms and chokes out native species.
  • Found in Betula, Jessica, and White Lakes in Whiteshell Provincial Park, Manitoba.
Whirling Disease

Whirling Disease is caused by a parasite that affects salmonids such as whitefish and trout. It has a complex life cycle that requires an aquatic worm, Tubifex tubifex, as a host. The effects of Whirling Disease can vary greatly depending on the species and age of the fish; young fish are the most susceptible.


Signs of infection include: infected fish swimming in a circular pattern (whirling) and changes in physical appearance including skeletal deformities of the body or head and/or a darkened tail.

Whirling Disease is not harmful to humans.

Where is Whirling Disease Present?

Whirling Disease was first discovered in Canada in Johnson Lake, Banff National Park in 2016. Since then, it has spread to multiple other watersheds within Alberta. Prior to that, it was detected in fish hatcheries in the USA in the 1950s.

Photo: Ben Vasquez


What are the chances of Whirling Disease occurring in RMNP?

The life cycle of Whirling Disease requires Tubifex tubifex worms and a salmonid fish. Clear Lake has both Tubifex tubifex worms and Lake Whitefish, which are part of the salmonid family. This means that if a contaminated vessel enters park waters it greatly increases the risk of a Whirling Disease infection.

Why can’t my watercraft be decontaminated?

Decontamination methods for Whirling Disease include using very hot water (90° Celsius) and/or harsh sanitization chemicals. These methods have proven to be damaging to both watercraft and the chemicals used are harmful to aquatic ecosystems.

Because we are seeing an influx of watercraft that had previously launched in infected areas and decontamination methods are not feasible at this time, we have made the decision to prohibit watercraft coming from moderate to high-risk Whirling Disease zones from launching in Riding Mountain National Park.

How does it spread?

Whirling Disease spores can remain viable at the bottom of a lake or river for 20-30 years and may become suspended in the water by wind, waves, or watercrafts. Once in the water column, the spores can be spread in multiple ways including:

  • Live fish or fish remains that contain the disease;
  • Watercrafts or equipment (i.e. fishing gear, chest waders, etc.) that come into contact with the disease;
  • Bait or bait buckets that have infected fish or contaminated water.

If you have information about unlawful use of live bait including minnows and leeches, please contact Parks Canada Dispatch 1-877-852-3100

How can you prevent the spread?

Ensure that you are following Riding Mountain National Park boating regulations (Fishing).

  • Never move live or dead fish, including remains, from one waterbody to another;
  • Do not transport water or sediment between bodies of water- Remember: CLEAN-DRAIN-DRY
  • Refrain from launching your watercraft in moderate to high-risk Whirling Disease zones;
  • Consider renting a local watercraft at your desired destination;
  • If you have used your watercraft in a moderate to high-risk Whirling Disease zone, please be advised that you will have to wait until the next season to launch;
    • This includes new boats that have been purchased and testing in high-risk areas;
    • Boats will be required to be exposed to seven days of below freezing temperatures or one full year without being in water;
  • Report sick or dead fish to Parks Canada Dispatch at 1-877-852-3100.

For more information, please contact: 204-848-7275

You can also visit: Canadian Food Inspection Agency: Whirling disease

Smallmouth Bass/Fisheries Operations

How did they get here?

We cannot say for sure. It may have been an intentional introduction, where someone illegally transferred smallmouth bass from another waterbody in hopes of creating a new recreational fishing opportunity. It also could have been an accidental introduction, where someone illegally used or dumped live bait in Clear Lake. Possession and use of leeches, minnows, and other fish parts as bait are prohibited in RMNP.

Parks Canada does not currently stock fish species in any National Park bodies of water, except in the case of restoring a population of a Species at Risk.

If you have information about unlawful use of live bait or the introduction of smallmouth bass, please contact the park wardens through Parks Canada Dispatch at 1-877-852-3100.

How can you help?

Ensure that you are following Riding Mountain National Park. fishing regulations

Starting in 2022, smallmouth bass is no longer subject to the game fish Catch and Possession Limit in RMNP. As a result, anglers who possess a valid fishing license are authorized to catch and possess as many smallmouth bass as they like. If you catch a smallmouth bass, retain it, euthanize it, and take it to the AIS inspection station at the Boat Cove. There, Parks Canada staff will measure the fish and collect information about where and when the fish was caught. Afterwards, you can choose to keep the fish or donate it for further research on population characteristics like age, health, and diet.

Thank you for doing your part to protect the ecological integrity of Clear Lake!

Walleye were also introduced. Why are they not considered an invasive species in Clear Lake too?

Walleye were introduced through federal stocking programs from the 1920s through the 1960s, ceasing in 1968. Over the last 60 years, Parks Canada’s perspective on stocking non-native fish species has evolved. Introducing non-native species can have unintended consequences for aquatic ecosystems, such as impacts to community dynamics like competition for food or habitat resources and spreading disease.

While the ecosystem impacts of the walleye introduction are unknown, they have been naturally reproducing and co-existing with Clear Lake’s native fish species for nearly a century and can be considered naturalized, meaning that they do not disrupt the native ecosystem.


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