Last August, we reported here that red swamp crayfish (Procambarus clarkii) was found in Tilbury. Unfortunately, these captures represented the first confirmed reproducing population of this highly invasive crayfish to Ontario’s waters and were confirmed in the field in June of 2025 by field crews from the federal and provincial governments, non-governmental organizations, including the OFAH Foundation, among others.
In total, 104 red swamp crayfish were captured over five days of surveillance and representing a risk to the Thames River and Lake St. Clair.
To make matters worse, in August of 2025, we received a report of a red swamp crayfish from Lake Aquitaine in Mississauga. A young naturalist used our newly published Guide to Ontario’s Crayfishes to identify the crayfish and posted it online to: www.iNaturalist.org
Shortly after, we worked with the Credit Valley Conservation Authority and the Department of Fisheries and Oceans Canada to follow up on the report. To date, a handful of red swamp crayfish have been confirmed from Lake Aquitaine.
Further surveillance efforts for Tilbury and Aquitaine are planned for the spring and summer of 2026. OFAH Foundation staff will work closely with partners to ensure we are doing everything we can to prevent this provincially prohibited species from spreading farther.
If you are in and around these areas, or on the water in general this summer, keep your eyes peeled and report any suspect crayfish or invasive species by calling the toll-free Invading Species Hotline at 1-800-563-7711 or report online at: www.EDDMapS.org
Download the new Guide to Ontario’s Crayfishes and other great resources at: www.invadingspecies.com/downloads/invasive-invertebrates
Originally published in the Walleye 2026 issue of Ontario Out of Doors
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