Zebra Mussels

About Species
Webinar about the Zebra Mussel population
How to properly clean your vessel
  • Small D-shaped mussels with brown and white stripes
  • Size of a fingernail
  • Microscopic larvae hide in infested water
Area Bodies of Water with Zebra Mussels
  • Housatonic River
  • Lake Zoar
  • Hudson River
  • Lake Lillinonah
  • Finger Lakes
  • Candlewood Lake
They can...
  • Damage your boat engine
  • Help blue-green algae take over lakes
  • Injure swimmers with sharp shells
You may find them...
  • Attached to boat hulls and trailers
  • In bilge & ballast water
  • In live wells
  • In boat engine nooks
A Brief History

In 2020, nearly 50 Zebra Mussels were discovered in Candlewood Lake and conservation efforts have been stepped up to reduce the possibility of their growth and subsequent damage to the Lake’s ecosystem.We are still evaluating the current state of the Zebra Mussel population in Candlewood. Please click here for a pre-recorded Webinar about the Zebra Mussel population in Candlewood as of 2/18/2021.

Zebra mussels are an invasive mollusk, not native to North America. They are usually spread via human activity (boats etc.), have no natural predators here, and can spread rapidly throughout a body of water. Once zebra mussels get established in a lake, there is little that can be done to completely eliminate them.  A lake with a hospitable environment can see rapidly increasing numbers of zebra mussels in a short period of time.  Ultimately, preventing zebra mussels requires all the boaters entering the lake to make sure they aren't transporting any hidden hitch hikers!  

Remove if found

Move boat away from the lake. Remove attached mussels and drain any water from bilge, ballast, etc. Wash boat thoroughly with hot, high pressure water.

Always CLEAN, DRAIN and DRY your boat, trailer, and equipment before entering Candlewood Lake.

Threats posed by this species
  1. They can change the lake’s ecosystem forever. They are filter feeders, filtering water (up to 1 liter per day per mussel), and they feed on the tiny organisms at the bottom of the food chain, thus stealing important resources from native species like sport fish.
  2. They can damage personal property by attaching themselves to boat hulls and anything with a solid surface, and clog water intakes on engines, small pipes etc.
  3. They can hurt you! They have sharp shells and can cover rocks on the lake bed, making walking on them dangerous without shoes.
How does this species spread?
Understanding how Zebra Mussels spread

One major pathway that zebra mussels can take to enter Candlewood Lake is attached to our boats and trailers, or hiding in our bilge/ballast water. The adult mussels can be found attached to your boat hull, motor, or trailer, while the microscopic larvae can stow away undetected in water from other water bodies in your bilge, ballast, or livewell.

How to protect Candlewood Lake from Zebra Mussels

"CLEAN - DRAIN - DRY" your boat, PWC, kayak, and equipment before coming to Candlewood from another body of water, as well as when you leave if you plan on traveling to another lake.  Click the link here for instructions on zebra mussels and how to properly clean your vessel.

More information

Check this map to see what areas have been searched already. Searched areas where mussels have not been found are marked in green, areas where they have been found are marked in red. 

Use this form to report your observations, even if you don’t find any zebra mussels. You can do it right on your phone, or take notes in the field and enter them on this form later. Your GPS coordinates can be found by simply clicking or tapping your location on a Google Map, or by using any of a number of GPS apps available for your phone.