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Lake Havasu Quagga Mussels
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What are quagga or zebra mussels?

Zebra mussels (Dreissena polymorpha) are small, freshwater bi-valve mollusks (relatives to clams and oysters) that are triangular in shape with an obvious ridge between the side and bottom. The zebra mussel gets its name from the black- (or dark brown) and white-striped markings that appear on its shell.

Quagga Mussels Lake Havasu

Where did quagga or zebra mussels come from?


Quagga mussels are native to the Dneiper River drainage of the Ukraine. Zebra mussels are native to the Caspian, Black, and Azov seas of Eastern Europe. These exotic mussels were first discovered in the United States in Lake Saint Clair, Michigan, in 1988 and are believed to have been introduced in 1986 through ballast water discharge from ocean-going ships. Since their initial discovery, zebra mussels have spread rapidly throughout the Great Lakes and Mississippi River Basin states and other watersheds throughout the eastern and central United States. Quagga mussels have not spread as extensively.

How did these invasive mussels get to Lake Havasu?

These invasive mussels in Lake Havasu are 1,000 miles farther west than any other known colony of zebra mussels.  The primary method of overland dispersal of these mussels is through human-related activities. Given their ability to attach to hard surfaces and survive out of water, many infestations have occurred by adult mussels hitching rides on watercraft. The microscopic larvae also can be transported in bilges, ballast water, live wells, or any other equipment that holds water.

What do they eat?

They are primarily algae feeders.  They feed by filtering up to a liter of water per day through a siphon.

Why should we be concerned about these mussels?

These mussels are filter feeders that consume large portions of the microscopic plants and animals that form the base of the food web. The removal of significant amounts of phytoplankton from the water can cause a shift in native species and a disruption of the ecological balance of the lake.

These mussels often settle in massive colonies that can block water intake and affect municipal water supply and agricultural irrigation and power plant operation.  In the United States, Congressional researchers estimated that zebra mussels alone cost the power industry $3.1 billion in the 1993-1999 period, with their impact on industries, businesses, and communities more than $5 billion.

Do these mussels have any predators?

These mussels do not have many natural predators in North America, but it has been documented that several species of fish and diving ducks have been known to eat them.

What can I do to help?

It is up to each of us to take extra precautions to stop the spread of mussels or any other invasive species. The following actions should be taken with any equipment used in potentially infested waters:

All equipment (e.g., dive gear, boats, trailers, motors, etc.) should be visually and tactically (by feel) inspected for the presence of zebra mussels prior to and after use in any water body. Additionally, any vegetation attached to this equipment must be removed and left at the site of origin.

Remove all sediment and gritty organic materials; these could actually be zebra mussel veligers (juveniles).

Clean and scrub boat hulls, motors, anchors and trailers. Then hose equipment with hot (140° F) and/or high-pressure water.  Bilges, live wells, and any other compartments that could hold water should be drained at the site of origin, and, if possible, flushed with disinfectant or hot water. All boat equipment should be allowed to remain completely dry for at least 24 hours before being used again.

Thoroughly clean all equipment in a saltwater bath (1/2 cup per gallon) or with warm tap water (104 ° F). Ensure that all equipment remains completely dry for at least 24 hours before being used again. Pay special attention to those areas and equipment that can hold water.

Take similar precautions with waders, bait buckets, and other equipment that can hold water or comes into contact with water.


Before leaving a lake or other waterway, always:

CLEAN the hull of your boat, remove all plant and animal material.

DRAIN the water from the boat, livewell and the lower unit.

DRY the boat, fishing gear, and equipment. If you are a day user, please wait five days before launching your boat someplace else. This five-day waiting period will aid tremendously in killing those hidden hitchhikers on your boat, such as the microscopic quagga larvae. Also, it is a good idea to wash the hull of your boat with high-pressure water, either at the lake, if washers are available, or after leaving the waterway.Visiting a self-help car wash that has high-pressure soapy water is an excellent idea either on your way home, or while on the way to the next lake – it can even help keep your boat looking new. Or, giving your boat a hot soapy bath when you get home can also help protect your investment and while also helping protect the next lake you visit. Remember, many of these aquatic hitchhikers can harm your boat as well. These invaders will attach themselves to boats and can cause damage to boat motors if they block the flow of cooling water through the engine.If you are moving a boat that has been moored on a mussel-positive lake, please take at least one of these extra precautions:

Power wash the hull so that it is clean “to the touch”

Bilge decontamination that consists of either a 140-degree hot water flush of the bilge spaces OR

A household vinegar flush of the bilge spaces, OR

A 27-day desiccation period where the boat is removed from the waterway and allowed to dry out; all through-hull fittings and bilge plugs must be opened to the air with no residual lake water allowed to remain standing in the bilge spaces; if, for any reason, water cannot drain or standing water remains in the bilge, it must be treated with heated water or vinegar solution. Quagga mussels do not pose a known threat to human health. Biologists are concerned that quagga mussels may cause ecological shifts in the lakes they invade, with consequences to valued wildlife resources. Because these invasive mussels attach to hard surfaces like concrete and pipes, they will affect canals, aqueducts, water intakes and dams, resulting in increased maintenance costs for those facilities.