All water-users play an important role as additional eyes and ears on the landscape to protect water bodies from new AIS invasions. If you suspect you have found an AIS, report it by emailing: AIS@gov.mb.ca or following the attached link: https://www.manitoba.ca/stopais/ais_reporting.html

Manitoba employs several complementary monitoring methods that target different life stages, types of AIS and differ in effectiveness seasonally and across waterbodies. These include:

Plankton tows

• A fine mesh net pulled through the water to capture Dreissenid mussel veligers (larval stage)
• Advantageous for early detection monitoring programs because veligers are free-floating and are generally more widely distributed within a waterbody relative to adults
• Veliger collections also allow for concurrent monitoring of Spiny Waterflea, and other AIS of concern.

Environmental DNA (eDNA)

• Describes the genetic material present within a water or sediment sample, which is shed from individuals through natural processes
• Extremely sensitive and requires specialized technology and analytical interpretation

Substrate Samplers

• Constructed of ABS and PVC, materials preferential for byssal thread attachment of settling/settled Dreissenid mussels
• Hung from docks and near other highly used areas
• Provides integrated, season long sampling

Shoreline Surveys

• Visual surveillance and tactile searches of waterbody margins and infrastructure to search for invasive aquatic plants, invertebrates and fish
• Occurs concurrently with other sampling methods

The goals of the Early Detection and Rapid Response (EDRR) program are to:

1. Detect new AIS invasions as soon as possible
2. Respond to these species before they become established.

Early detection and rapid response plans are initiated by a positive AIS detection identified by the surveillance monitoring program, or through a verified report from the public.

The goal of EDRR is elimination of further risks associated with the presence of an AIS, which is likely only achieved through eradication (i.e., complete removal of every potentially reproducing individual). Early detection of AIS is important for response efforts since the likelihood of staging a successful eradication is greater during early-stage invasions. Eradication may only be feasible under very limited circumstances depending on the species detected and where the detection occurred. Thus, the EDRR program encompass a range of responses, including eradication, containment, suppression, among others.

St Malo Reservoir

Live zebra mussel veligers were found within the St Malo Reservoir during several independent sampling events between June and August 2024 including positive eDNA samples. No zebra mussel positive samples were detected upstream of the reservoir in the Rat River, indicating the introduction is a result of human-caused introduction to the reservoir and not from upstream water movement.

Response

St. Malo Reservoir is currently under Restricted Access. In this case, Manitoba has restricted watercraft and water-related equipment from the reservoir UNLESS water users follow standard clean, drain dry requirements and additionally, items must also be decontaminated before being used in any other water body in Manitoba.

Manitoba continues to assess the feasibility eradicating zebra mussels within the reservoir.

Upper Assiniboine River

Dead zebra mussel veligers were detected in the Assiniboine River at the Brandon Generating Station as part of Manitoba Hydro's routine monitoring program and confirmed in follow up sampling. Manitoba initiated its Early Detection and Rapid Response plan which includes the development and implementation of a validation monitoring plan and a containment plan.

Based on the available evidence, Manitoba is currently unable to determine whether this detection at the Brandon Generating Station is a result of:

1. a new introduction of zebra mussels into the Assiniboine River,
2. a new introduction of zebra mussels into the Little Saskatchewan River, or
3. downstream movement of zebra mussels from Clear Lake in Riding Mountain National Park via the Little Saskatchewan River. There is a known population of zebra mussels in Clear Lake near the Little Saskatchewan River's headwaters.

With these uncertainties in mind, a containment plan was developed that includes both the Assiniboine and Little Saskatchewan Rivers. To contain the potential outward spread of zebra mussels to new water bodies, Restricted Access signage has been posted along the following river reaches, including:

• along the Assiniboine River from Provincial Rd 250 bridge crossing (approximately 15 km upstream of the Little Saskatchewan River confluence and 30 km upstream of the Brandon Generating Station) downstream to the Portage la Prairie/Lake Manitoba diversion.
• along the Little Saskatchewan River from its confluence with the Assiniboine River upstream to its confluence with Clear Creek, including Lake Wahtopanah and Minnedosa Lake reservoirs.
• the entire length of Clear Creek within Manitoba jurisdiction, from its confluence with the Little Saskatchewan River to the Riding Mountain National Park Boundary.

A map of these areas can be found by clicking here.

Response

Restricted Access signage was posted in this larger area indicating decontamination of watercraft and water-related equipment is required before items are used in a different waterbody. This follows the same requirements that exist for Aquatic Invasive Species Control Zones.

Restricted access status is subject to change based on monitoring results, which could include expanding or contracting the intended restricted areas listed above. Any such changes to the containment plan would be communicated appropriately.

On-going Responses – Validation Monitoring

Four waterbodies currently fall under the validation monitoring protocol of the Early Detection and Rapid Response program: Foot Print Lake, Assean Lake, Lake of the Woods and Shoal Lake (on the Manitoba-Ontario Border).

Foot Print Lake

Foot Print Lake had an initial detection of spiny waterflea in 2022, a subsequent detection in 2023 and no detections in 2024. Spiny waterflea are notoriously patchy and highly seasonal, a lack of findings in 2024 does not provide a high level of confidence that a population is not present. Further monitoring of the waterbody is required to confirm this detection, and therefore, will continue to undergo validation monitoring.

Assean Lake

Zebra mussel veligers were first detected within Assean Lake in 2019 and found again in 2020, albeit at low densities. Intensive monitoring from 2021 to 2024 failed to find further veligers. Validation monitoring of Assean Lake will continue throughout the 2025 open-water season.

U.S. Portion of Lake of the Woods

Zebra mussel veligers were detected in the U.S portion of Lake of the Woods in 2019. Subsequent monitoring by U.S counterparts continues to find low densities of veligers, suggesting a slowly increasing population. To date, no zebra mussels have been detected in the Canadian portion of the lake.

Shoal Lake

Shoal Lake, a waterbody of shared jurisdiction between Manitoba and Ontario, and the source of the City of Winnipeg's drinking water, had a detection of a single zebra mussel veliger in 2018. Joint monitoring efforts by Manitoba and Ontario authorities have yet to find other zebra mussel positive samples since the initial detection.

Use of separate watercraft or water-related equipment for each water body greatly reduces the risk of humans transporting AIS from one water body to another.

For example:

• rent or use locally supplied watercraft and equipment rather than transporting and using your own.
• use specific equipment, like angling gear and nets in an invaded area and use a different set of equipment for non-invaded areas.
• suggest to visiting friends and family that they use your locally kept and used items rather than bringing and using their own.

Decontamination is not required for dedicated equipment since the items are kept and used only for the same water body.

In Manitoba, whenever items (e.g., watercraft, inflatables, fishing gear, anchor) come in contact with a water body, the Clean, Drain, Dry actions are required. These sequential steps each add layers of protection against the spread of AIS by humans and apply year-round.

The risk of humans spreading AIS to other areas is much greater after being in an areas with an AIS detection or known AIS invaded area (e.g., control zones). These greater risks are met with a corresponding level of AIS protection.

When an AIS has been found or is otherwise present, Manitoba can restrict public access to the area. Restricted access is part of the suite of tools available to contain or eradicate an AIS.

In some cases, Restricted Access may require decontamination of watercraft and water-related equipment before entering a different water body, as is frequently employed during zebra mussel responses. Other Restricted Access conditions may include guidance on avoiding disruption of certain areas which may contain an AIS species. Under specific circumstances, site access may be restricted entirely.

Restricted Access Signage

Restricted Access signage (Figure. 1) notifies water-users of their need to comply with additional AIS prevention measures and requirements specific to the nature of the AIS response within a given area and/or water body.

For more information on AIS detections and the corresponding Restricted Access measures, click here.

An example of a type of Restricted Access sign