Zebra Mussels

Zebra Mussels

What are Zebra Mussels and where can they be found?

Zebra Mussels (Dreissena polymorpha) are small freshwater mussels which are approximately an inch long, and are native to the streams and lakes within the Black Sea region of Eastern Europe and Western Asia. The Zebra Mussel gets its name from the dark, striped pattern on their shells. Usually the shell is a light colour (tan or beige) with darker zig-zag stripes. The average life span for an individual mussel is approximately four to five years.

Zebra Mussels on lifebuoy at Kelso CAZebra Mussels are believed to have hitch-hiked from Europe to North America in ballast water from transoceanic ships. They were first observed in Ontario in 1988 and have spread throughout the Great Lakes, Lake St. Clair and the Mississippi River watershed. The range expansion of Zebra Mussels continues to grow with additional observations in Lake Simcoe, Thames River and now Sixteen Mile Creek.

Zebra Mussels were first seen in Kelso Reservoir in the fall of 2013 when a small number of mussels were seen attached to a boat. They have spread throughout the reservoir along rocky shorelines and natural debris (logs, tree stumps) within the reservoir and also attached themselves to infrastructure below water including boardwalk piers, safety buoys and walls adjacent to Kelso Dam.

They disperse downstream on water currents during their free-floating larval stage. They are only able to disperse into upstream areas, like Kelso Reservoir, through human activity. Like other new infestations of Zebra Mussels, it is believed they were introduced to the Kelso Reservoir as attached mussels or veligers (larvae) to an infested recreational boat or were dumped into the reservoir from a live well or bait bucket.

How they impact humans and wildlife

The impacts of Zebra Mussels include:

  • Filter water to the point where food sources such as plankton are removed and alter the food web for other species
  • They can impact fish and other wildlife by increasing algal blooms and large colonies affect fish spawning areas
  • Impact infrastructure and recreational equipment by clogging pipes resulting in damage and maintenance
  • Their sharp shells can cut a swimmer’s foot
  • They can have health impacts on fish, wildlife and humans. Zebra Mussels filter contaminants from the water, and can move them up the food chain as mussels are consumed by fish and wildlife

What is Conservation Halton doing about Zebra Mussels in Kelso?

Conservation Halton is undertaking two main steps, monitoring and managing. Conservation Halton is monitoring the presence of Zebra Mussels in Kelso Reservoir and other parks with lakes and dams – Hilton Falls, Mountsberg and Robert Edmondson. Staff implemented a baseline inventory of Sixteen Mile Creek in the stream reaches immediately downstream of the Kelso Reservoir, to assess if Zebra Mussels have spread downstream in 2015. Juvenile Zebra Mussels were found throughout the study area attached to stream substrates as far downstream as Kelso Road. Long-term monitoring of the population downstream of the Kelso Reservoir will continue in 2016 and subsequent years.

Staff are evaluating options to manage and address the population within Kelso Reservoir. The normal lowering of water levels each year is helping to manage the population as it exposes the Zebra Mussels to the air for long periods of time, typically over the winter months. This results in mussels dehydrating and freezing in the exposed areas of the reservoir. Unfortunately only one or two Zebra Mussels can cause an infestation and many are still able to survive in the water which remains in the reservoir during winter.

What can you do to help stop the spread?

  • Inspect all recreational equipment that is submersed in water (boats, canoes, paddleboards, trailers, paddles and bait buckets) after each use. Remove all plants, animals and mud before leaving the area
  • Drain water from motor, bilge, live wells, and buckets while on land and away from a water source. Flush equipment with hot tap water.
  • Do not re-use bait from infested waters. Any live bait should be disposed of properly in the garbage to prevent introductions of zebra mussels and other non-native or invasive species into new areas.
  • Rinse all recreational equipment used in infested waters with high pressure hot water, or let it dry in the sun for at least five days.
  • If you find Zebra Mussels or other invasive species in the wild, please contact the toll-free Invading Species Hotline at 1-800-563-7711.

Are Zebra Mussels edible?

Most clams and mussels are edible, but that does not mean they taste good! Many species of fish and ducks eat Zebra Mussels, so they are not harmful in that sense. However, since they are filter feeders, they can accumulate contaminants in their body that can be passed up the food chain. If a fish eats a mussel, and a person eats the fish, the person can be ingesting a significant amount of contaminants. To be safe, it is not recommended to eat Zebra Mussels.

Further information on how to reduce contamination from eating wild fish can be found in the “Guide to Eating Ontario Fish”, which you can view online, or obtain a copy from the Ministry of Natural Resources and Forests.