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Lake Manitoba Zebra Mussel Detection


In late July 2021 zebra mussel veligers (larval stage) were detected in water samples collected from Lake Manitoba Narrows. These samples were taken as part of the Aquatic Invasive Species (AIS) Unit’s annual surveillance monitoring.

Veligers were found in all nine samples taken from this area of the lake in quantities ranging from two to 12 veligers per sample. Additionally, environmental DNA (eDNA) samples taken by Oceans and Fisheries Canada at the Narrows, were positive for zebra mussel DNA.

Subsequent sampling has revealed various zebra mussel life stages. As a result, this indicates there is a reproducing population in the lake.

It didn’t have to be this way

In Manitoba, to prevent the spread of aquatic invasive species, such as zebra mussels, water users using watercraft and water-related equipment in a water body must follow the general AIS requirements.

As well, watercraft and water-related equipment must be also decontaminated prior to placing them into another water body if they were last used in:

  • an Aquatic Invasive Species Control Zone
  • an invaded water body e.g., Lake Manitoba, Assean Lake
  • a tributary to the first impassible barrier or connected water body of a control zone or an invaded water body


Restricted access signage (as shown) is placed at access points of invaded water bodies that are not yet designated as AIS Control Zones. This includes water bodies such as Lake Manitoba. The signs are to notify surface water users of this decontamination requirement.

Prevention is our best defense

It is essential that all water-users follow the AIS requirements to prevent the spread of aquatic invasive species.

In Manitoba, it is illegal to possess, transport, import or release an AIS.
The set fine for individuals:

  • possessing an AIS is $1,296
  • transporting an AIS is $1,296
  • failing to decontaminate a watercraft used in an AIS Control Zone prior to launch in another water body is $2,542
  • releasing an AIS in Manitoba is $2,542

Set fines for AIS offences are in effect year round.

Provincial watercraft inspection stations can assist surface water-users with inspections and decontaminations. Operating hours and locations of the watercraft inspection stations can be found here.

The open-water season and the winter (ice-covered) season checklists are helpful resources that can help you comply with the AIS requirements.



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