Muskoka's Invasive Animals

Invasive Animals in Muskoka

              Throughout most of Ontario, the Great Lakes region, and Muskoka there has been a silent invasion happening for quite some time, the invasion of invasive animal species. An invasive species is a species that is not native to a specific location (an introduced species), and that has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health. These invasive species change the balance of the ecosystem by competing with native animals for food as well as spawning grounds. They tend to be prolific breeders and voracious eaters usually targeting newly hatched native animals and microscopic organisms.


  • Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a backbone or spine). Familiar examples of invertebrates include arthropods (insects, arachnids, crustaceans), mollusks (chitons, snails, bivalves, squids, and octopuses), annelids (earthworms and leeches), and cnidarians (hydras, jellyfishes, sea anemones, and corals).

  • The Rusty Crayfish is found in Manitoulin, Kawartha and Magnetawan areas and was likely introduced as released bait or aquarium pets. They compete with native crayfish eat fish eggs and cross breed with native species, diluting the species

  • Chinese mystery snails and Banded mystery snails are found in the Trent – Severn water system and in Kawartha Lakes. They were originally introduced as a food source and for aquariums. There has been very little study on their impact except to assume that they compete with native snails for food.

  • Recently flags have been raised about the impacts of the Spiny water flea in over 100 inland lakes including many in Muskoka. It likely arrived in ballast water and is easily transported in or on fishing boats or gear and bait pails. It can colonize with a single female so once present, it can dominate. This species changes the zooplankton communities, competes for food, can foul fish lines and can kill predator fish as it is indigestible.

  • The most recent emergence has been from the freshwater jellyfish. This is a non – native species that is here to stay as there is no known way to remove jellyfish from a lake ecosystem. It is thought that the jellyfish were stowaways on aquatic plants imported to Europe in the 1800s where they then got a ride to Philadelphia in boat ballast. This is likely the same way they were introduced into Ontario, via a contaminated ship or plant. These animals are native to the Yangtze River in China and were first discovered in Georgian Bay in the 1950s and in Lake Muskoka in 2002. Unlike some of the other invertebrates named above it is widely believed that freshwater jellyfish are unlikely to pose a threat to the ecosystem or to humans. They are eaten by native species such as turtles and crayfish and are not known to sting people.



  • In the province of Ontario 17 species of fish have been identified as invasive with 3 being identified in or around Muskoka

  • The first being White Perch which can be found in the Trent-Severn system. These animals are native to the Atlantic seaboard and likely came to the great lakes in the 1900s. They compete with native species for food and change the makeup of the ecosystem. They also typically spawn between 20,000 and 150,000 eggs causing their numbers to increase rapidly.

  • The Round Goby is a small, bottom-dwelling invasive fish. It is believed to have been brought to Ontario waters via ballast water from Europe. In less than a decade it has successfully spread through all five Great Lakes and has begun to invade inland waters. They prefer waters with rocky and sandy bottoms. They feed aggressively on insects and other small organisms found on lake and river bottoms. Their aggressive eating habits and ability to spawn several times each season have helped them multiply and spread quickly. This fish impacts the ecosystem by competing with and preying on other native bottom-dwelling fish, as well as reducing the populations of sport fish by eating their eggs and young.

  • The Rainbow Smelt is a predatory fish that is native to the north Atlantic coastal regions of North America. Deliberate stocking in Michigan in the early 1900s led to established populations in the Great Lakes. More recently people have illegally introduced smelt to inland lakes. By competing with other fish for food and eating the young of other species, Rainbow Smelt has had a serious impact on native species that eat plankton, as well as those that eat other fish. This animals’ eating habits may disrupt food webs and lead to declines of the small animals known as zooplankton that are eaten by other fish. Introduction of Rainbow Smelt has led to reduced populations of native fish species such as yellow perch, walleye, lake herring, whitefish, and lake trout. Rainbow smelt eats the young of other species and may then be eaten by other adult fish, resulting in higher concentrations of contaminants in native fish that may be a human health risk.


Reporting Invasive species

  • If you find an invasive species on your property or in your community, report it by calling the Invading Species Hotline at 1-800-563-7711, or online by using EDDMapS Ontario

  • EDDMapS Ontario is a website and app where you can: report sightings of invasive species, get information and photographs of more than 150 invasive species, view invasive species sighting reports and maps, contribute to a community of citizen scientists, and search for and download records by invasive species and location


We at HRC Insurance hope that this blog helps you understand what invasive species are doing to our ecosystem. If you see any of these animals or any invasive plant life always be sure to report them to the relevant authorities. If we are diligent we might be able to stop these invaders!  

Since the 1900's...

Born under the name George Hutcheson, Hutcheson, Reynolds & Caswell Ltd. began providing insurance policies in Muskoka since the early 1900s. Bernard Reynolds joined the firm in the 1940s and purchased the firm from George Hutcheson in 1967. Finally, in 1980, David Caswell joined the company's ranks to complete Hutcheson, Reynolds and Caswell. We have grown along with our name and provide the same dedication to superior customer service and top-notch insurance coverage that George Hutcheson was famous for over 100 years ago.