Zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena rostriformis bugensis) are small, fingernail-sized freshwater mollusks native to freshwater lakes in Russia and Ukraine and are non-native to North America.

They have a distinct striped pattern, hence the name “zebra” and “quagga” (an extinct subspecies of Plains Zebra).

They were first introduced to Canada’s Great Lakes region and the United States in the 1980s after ballast water was discharged by vessels traveling from Europe.

Zebra mussels can have significant negative impacts on ecosystems. They outcompete native species for food and habitat, leading to declines in native mussel populations, fish, and other aquatic organisms. They can also disrupt food chains, alter water quality, clog water intake pipes, and cause damage to infrastructure.

Invasive mussels use their byssal threads to swim and attach to watercraft, including boats, kayaks and paddleboards, hip waders, tackle boxes, life jackets – any hard surface that has spent time in infested waters. They can also be transported in water-filled containers, such as bait buckets, and can live 30 days out of water in a damp space.

At their youngest stage, the invasive mussels are microscopic – about the size of a grain of sand. At their largest they are the size of your thumbnail (1.5 to 2 cm) and have a distinct D-shaped shell with alternating light and dark stripes.

Invasive mussels promote toxic algae blooms that pollute water, putting swim areas and drinking water at risk. Their sharp shells have also been known to cut feet.

They also damage in-lake infrastructure like water intakes, outfalls, docks and other in-water equipment. They can also clog water treatment and power plant infrastructure, requiring increased tax dollars to treat.

These mussels are filter feeders, meaning they extract microscopic organisms, plankton and organic particles from the water column. While this may initially improve water clarity, their high densities can result in the depletion of food resources for other species and lead to harmful algal blooms and reduced water quality.

Controlling zebra and quagga mussels is challenging. Their ability to reproduce rapidly, attach to surfaces and spread through water currents makes eradication difficult. Control measures typically focus on managing their populations and minimizing their impacts.

Some methods used to manage zebra mussel populations include draining of a reservoir, chemical treatments, physical
removal, and biological control with the use of natural predators or parasites.

At this time, none of these options are feasible for the Okanagan, except an ongoing removal program, similar to the way invasive milfoil is managed on a continuing basis.

The best way to prevent introducing zebra and quagga mussels into the Okanagan’s waters is by keeping vigilant and following clean, drain, dry protocols with all water toys when leaving a waterway and before launching in another waterbody.

Zebra and quagga mussels are found in freshwater environments such as lakes, rivers, and reservoirs. They cannot tolerate the high salinity of saltwater.

The Okanagan region is valued for its high biodiversity and is home to some of the most endangered species in Canada. Among those at risk is our own native Rocky Mountain Ridged Mussel, a large mussel that can grow almost five inches in length. Zebra and quagga mussels outrival native species for food, causing a negative shift in the food web. In addition, they can create toxic algae blooms that contaminate lake water and kill fish and birds.

Boaters and recreational water users can help prevent the spread of zebra/quagga mussels by cleaning and inspecting their boats and equipment, removing any visible plants or animals, draining water from all compartments, and drying equipment thoroughly before moving to another water body. Ideally, avoid launching in more than one waterway per day to allow your equipment to fully dry.

Eating the mussels is not recommended since they accumulate toxins as they filter water. They’re also pretty small! These toxins can also harm pets and birds.

Zebra mussels have few natural predators in their non-native habitats. Some fish species, such as drum, crayfish and some waterfowl will eat the mussels, but native species often lack the ability to crush the shells. Plus, their ability to control the mussel populations would be limited.

Zebra/quagga mussels impose significant economic costs. They can clog water intake pipes of power plants, water treatment facilities and industrial facilities, leading to increased maintenance and operational expenses. They can also damage boats, docks and infrastructure, resulting in costly repairs. Additionally, the mussels can reduce recreational opportunities, impacting tourism and local economies.

A single female zebra mussel can produce up to a million eggs per year. In some areas with warm waters, like Lake Mead, there have been six to eight reproductive cycles a year.. They have a free-floating larval stage called veligers that can be transported by water currents, facilitating their rapid spread to new areas.

In their native range, zebra and quagga mussels have natural predators, such as diving ducks and some fish species. However, in non-native habitats, the absence of these predators contributes to the rapid spread and population growth of zebra mussels.

Signs of a water body infested with zebra mussels may include large numbers of adult zebra mussels attached to hard surfaces such as rocks, docks, or boats. Water intake structures may be clogged with zebra mussels, and their sharp shells may accumulate on beaches and shorelines.

However, at the earliest stages of an infestation, the mussels may be difficult to detect since they are microscopic at their youngest stage. And since the best chance of dealing with an infestation is to act as early as possible, water samples from a number of Okanagan and B.C. waterbodies are collected and tested on a regular basis.

The public can play a crucial role in preventing the spread of zebra mussels. Some ways to get involved include:

  • Cleaning and inspecting boats, trailers and equipment before and after entering water bodies.
  • Removing any visible plants, animals or debris from boats and equipment.
  • Draining water from all compartments and equipment.
  • Drying boats and equipment thoroughly before launching them in another water body.
  • Following local regulations and participating in educational programs or campaigns to raise awareness about invasive species and their impacts.
  • Talking with your family and friends about the importance of stopping at all inspection stations along their travel route, and cleaning, draining and drying watercraft before launching them in the Okanagan’s waters.

Yes! The B.C. government has introduced a pull-the-plug order requiring anyone hauling watercraft on B.C. roads to travel with drain plugs pulled.

Also, there are six permanent and two roving inspection stations for 2024.

If you are transporting any type of watercraft in B.C. (boat, kayak, paddleboard, etc.) it is mandatory to stop and report to all provincial invasive mussel watercraft inspection stations along your travel route. Failing to stop at a B.C. inspection station can result in a $345 fine. In addition to a $345 fine for failure to stop at an open B.C. inspection station, those hauling watercraft can face the following:

Allowing an aquatic invasive species (AIS) to escape for a first time offender:

  • fines ranging from $2,500 to a maximum of $250,000; or
  • a term of imprisonment not exceeding two years;
  • or both a fine and a sentence.

Failing to comply with an officer’s order to remove mussels from watercraft and equipment for a first time offender:

  • fines up to a maximum of $100,000; or
  • a term of imprisonment of one year;
  • or both a fine and a sentence.

Possessing, failing to prevent AIS from breeding, shipping or transporting or failing to safely dispose of waters used to clean or remove mussels for a first time offender:

  • fines up to a maximum of $50,000; or
  • a term of imprisonment not exceeding 6 months;
  • or both a fine and a sentence.

Importing, possessing, transporting, releasing or engaging in an activity that may release AIS is prohibited and subject to fines upwards of $100,000 under the Federal Fisheries Act.