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Spiny Waterflea

Sneaky Little Creatures

The spiny waterflea is a non-native species of zooplankton introduced from Eurasia into the Great Lakes in the ballast of ocean-going ships in 1982. It has now spread to over 100 inland lakes. The spiny waterflea has been observed in Nepahwin Lake as well as Wanapitae, McCharles, Panache and Wavy Lakes. Currently there is no way to remove spiny waterflea from a lake.

Why Are They Harmful?

Although spiny waterfleas are not harmful to humans or pets, do not carry disease, and do not affect lake water quality for swimming, their presence can be harmful to our aquatic ecosystems. Researchers believe that spiny waterfleas are the greatest threat to the biodiversity and structure of native zooplankton communities on the Canadian Shield since acid rain.


  • A few animals can quickly multiply into a large population.

  • Because their main diet is native zooplankton, they reduce food supplies for small fish and the young of sport fish such as bass, walleye and yellow perch.

  • Spiny waterflea introductions result in an average 30 to 40 per cent decline in native populations of zooplankton.

  • Dense clusters of spiny waterfleas can disrupt residential water intake lines.

What Can You Do to Stop the Spread?


They are easily spread between water bodies on watercraft, angling equipment, bait buckets, live wells bilge waters and even swimsuits. To decrease the spread to other inland lakes, take the following precautionary actions:

  • Learn how to identify spiny waterflea. Try to preserve the organism in rubbing alcohol.

  • Inspect your boat, trailer and equipment after each use. Remove all plants, animals and mud before moving to a new water body.

  • Drain water from your motor, live well, bilge and transom wells while on land.

  • Rinse all recreational equipment with high pressure (>250 psi) or hot water (50°C/122°F) OR let it dry in the sun for at least five days.

If you’ve seen an invasive waterflea or other invasive species in the wild, please contact the toll-free Invading Species Hotline at 1-800-563-7711, or the local Ministry of Natural Resources and Forestry office at 705-564-7823. 

City of Greater Sudbury:
Ontario’s Invading Species Awareness Program:

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