What are zebra and quagga mussels and where did they come from

Zebra and quagga mussels are freshwater, bivalve mollusks that typically have a dark and white (zebra-like) pattern on their shells. They are alien to North America but have invaded many of our waters. Despite some minor appearance and ecological differences, the species are very similar and pose a significant threat to our waters.

Both species, in general, are usually about an inch or less long, but may be larger. When healthy, they attach to hard substrates. much like marine (saltwater) mussels but unlike any native freshwater bivalve. They are often found in clusters.

Zebra and quagga mussels are native to Eurasia. Until the mid 1980s there were no zebra mussels in North America. It is suspected that zebra mussels hitched a ride in ballast water tanks of commercial ships. Zebra mussels were first discovered in the United States in Lake St. Clair near Detroit, Michigan in 1988. 

Since the 1980s, zebra mussels have spread, unchecked by natural predators, throughout much of the eastern United States. They currently infest much of the Great Lakes basin, the St. Lawrence Seaway, and much of the Mississippi River drainage system. The have spread up the Arkansas River into eastern Oklahoma. Quagga mussels invaded North America later than zebra mussels and have been confirmed in fewer waters, including the Great Lakes, the St. Louis area and now in the Lower Colorado River. 

In November 2016, state officials announced the first documented presence of zebra and quagga mussels in Montana, after positive tests at sites in the Missouri River system in Tiber Reservoir, and “suspect” detections in Canyon Ferry Reservoir. 

Tiber was put under a five-year monitoring study and Canyon Ferry under a three-year monitoring. At the end of 2019 Canyon Ferry was determined to be suspect mussel free, and restrictions were lifted. Tiber will be monitored two more years 2020 and 2021; if mussels aren’t detected the restrictions will be lifted.

When they are present in North American waters, they are usually millions of them. Zebra/quagga mussels are what scientists and engineers call “biofoulers” that block pipes in municipal and industrial water systems, requiring millions of dollars annually to treat. Zebra mussel densities have been reported to be over 700,000 individuals per square meter in some facilities in the Great Lakes area. They produce microscopic larvae that float freely in the water column, and thus can pass by screens installed to exclude them. Monitoring and control of zebra and quagga mussels costs millions of dollars annually.

Zebra/quagga mussels also negatively impact aquatic ecosystems, harming native organisms (including already imperiled indigenous mussels). In huge numbers, they out-compete other filter feeders, starving them. They adhere to all hard surfaces, including the shells of native mussels, turtles, and crustaceans. Zebra/quagga mussels actively feed on green-algae and may increase the proportion of foul-smelling blue-green algae in water systems.


IMPACTS OF AIS

Aquatic invasive species pose a threat to the environment, economy, recreation, and human health in Montana.

Environmental Impacts

Humans have created conditions where plants and animals can aggressively invade and dominate natural areas and water bodies in three ways:

• Introducing non-native species from other regions or countries that lack natural competitors and predators to keep them in check.

• Disrupting the delicate balance of native ecosystems by changing environmental conditions – e.g., stream sedimentation, ditching, building roads – or by restricting or eliminating natural processes – for example building a dam. In such instances, even some native plants and animals can become invasive.

• Spreading aquatic invasive species through various methods – these include moving watercrafts from water body to water body without removing invasive plants and animals and releasing bait into water bodies.

The net result is a loss in diversity of our native plants and animals as invasive species rapidly multiply and take over. About 42 percent of the species on the federal threatened or endangered species lists are at risk primarily because of invasive species.

In U.S. water bodies, the rapid spread of zebra mussels shows how profoundly an AIS can alter the environment. These tiny mussels with huge appetites for microscopic plants and animals rapidly reproduce and are capable of severely altering their environment by reducing the food supply for native organisms and by enhancing conditions for the rapid growth of blue-green algae and aquatic vegetation. 

Avian Botulism

In the Great Lakes, researchers are trying to determine if zebra mussels promote conditions for the growth of avian botulism, which have caused massive bird fatalities in the past few years, especially on Lake Michigan.

Heavy Metals

Aquatic invasive species affect the amount of heavy metals in our waters in two ways. First, many aquatic invasive species (like zebra and quagga mussels) are filter feeders, meaning they filter the water for free-floating microscopic organisms to feed on. However, this process can cause accumulation of heavy metals in the tissues of filter-feeders, which can in turn lead to increased levels of heavy metals in the surrounding sediments in areas with high densities of invasive mussels. Second, anti-biofouling boat paints and coatings that are used to keep zebra and quagga mussels from attaching to boats are usually made with copper or other toxicants. The increased use of these paints has led to higher levels of copper and other heavy metals in harbors and surrounding areas.

Economic Impacts

• In the United States, expenses associated with ecological damage and control of invasive species is estimated at $137 billion per year and increasing.

• In Montana, some industries affected negatively by AIS include sport and commercial fishing, agriculture and raw water users – i.e. power companies and utilities. In the case of power companies and utilities, expenses from AIS are passed on to Montana consumers – in the form of higher water and electric bills.

• In 2007, Montanans and visitors spent $343 million on fishing across the state. In the Upper Missouri River reservoirs alone, the money spent on fishing is estimated as $13.7 million dollars annually from 1989 to 2011. This could change drastically if invasive species take hold in these waters.

• In the United States, congressional researchers estimated invasive mussels cost the power industry $3.1 billion in the 1993-1999 period, with its impact on industries, businesses, and communities over $5 billion (New York Sea Grant 1994a). In Canada, Ontario Hydro has reported zebra mussel impacts of $376,000 annually per generating station (New York Sea Grant 1994b).

• A study has recently shown that the presence of dense, mat-like aquatic invasive plants decreases property values up to 16 percent.

Recreational Impacts

• Aquatic invasive species can also alter your recreational activities. Hunters, anglers, and even birdwatchers, among others are impacted by AIS and may find that they are no longer able to comfortably swim, or easily navigate their favorite water bodies. Also, as the habitat is modified by these invaders, the wildlife that depends on it disappears.

• Fishing outings can result in disappointment when AIS modify our lake and stream habitat. Eurasian watermilfoil can clog boat motors and invasive animals such as the rusty crayfish gobble up aquatic plants like underwater lawn mowers, reducing habitat for native fish at every stage of their life cycle. The invading crayfish may even eat the eggs of our favorite sport fish.

• Boats can be damaged by mussels! Proper boat hull, engine maintenance and cleaning are key to saving thousands of dollars in repair costs resulting from damage caused by zebra and quagga mussels. Juvenile and adult mussels can attach to many different types of substrate including fiberglass, aluminum, wood, and steel. This ability to attach decreases fuel efficiency and damages the boat’s finish. Their larvae (called veligers) are extremely small – too small to see without a microscope. When veligers are present in the water they can be drawn into engine passages or can move into them on their own. Once they settle out in the engine cooling system, they can grow into adults and may block intake screens, internal passages, hoses, seacocks, and strainers.

Health Impacts

Some invasive species may cause significant health problems. For example, a South American strain of human cholera-causing bacteria was found in ballast water tanks of ships in the port of Mobile, Alabama in 1991. Also, sharp zebra mussel shells can cut the feet of unsuspecting swimmers and waders. Zebra mussels “clean” the water by removing the phytoplankton at the base of the food chain which can then affect species higher up on the food chain including game fish. This also allows sunlight to reach higher depths which can increase unwanted plant growth.

Swimmer’s Itch

Swimmer’s itch is caused by the larvae of certain parasitic flatworms that can burrow into your skin while swimming. Humans are not the intended host of this parasite (waterfowl are the intended hosts) but can become an accidental host. Invasive species such as certain snails and plants can harbor the organism’s causing swimmer’s itch and therefore increasing its occurrence in infested water bodies.


CLEAN. DRAIN. DRY.

CLEAN: Completely remove all mud, water and vegetation before leaving access area.

  • Cleaning will remove visible large-bodied organisms attached to or in watercraft or recreational equipment. Rinsing with water removes organisms, while hot water often kills them.
    • Water at least 120°F is recommended; be sure to avoid contact with skin and check manufacturers’ recommendations to ensure equipment can withstand high temperatures.
    • If hot water is not available or may cause damage, rinsing with tap water and completely drying will help prevent spread of aquatic invasive species.
  • Inspect your boat, trailer, and all gear. Pay attention to crevices and hidden areas.
  • Remove all mud and vegetation.  Use a pressurized power sprayer found at most do-it-yourself car washes.  The hot water kills organisms and the pressure removes mud and vegetation. No need to use chemicals or soap.
  • Dispose of vegetation and debris in trash or on dry land away from water or ramp.

DRAIN: All water from watercraft and equipment.

  • Draining removes small and nearly invisible organisms such as invasive mussel larvae (veligers) that can be found in standing water.
  • Drain or remove water from boat, bilge, live well, engine, internal compartments, and bait buckets by removing drain plugs before leaving the access area.

DRY: Your watercraft and equipment. Aquatic invaders can survive only in water and wet areas.

  • Dry your watercraft and fishing equipment thoroughly; this will kill most invasive species.  The longer you keep your watercraft, trailer, waders, and other equipment outside in the hot sun, the better.
  • Drying is necessary as many organisms can survive in standing water.  
  • Dry in the sun (drying times will vary) or use a towel.

Planning to Bring Watercraft into Montana?

All watercraft entering Montana are required to be inspected for aquatic invasive species. You must obtain an inspection before launching on Montana waters. Stop at all open inspections stations you encounter. 

  • Boats with a ballast or bladder, such as wakeboard or wake-surfing boats, that intend to launch on Montana waters must obtain a decontamination before launching.
  • If you do not encounter a Montana watercraft inspection station while traveling, inspections conducted in Idaho and Wyoming fulfill Montana’s inspection-before-launch requirements. Stop at ALL open inspection stations you encounter in Montana where your watercraft may be re-inspected.

Non-resident watercraft launching in Montana must purchase a Vessel AIS Prevention Pass (AISPP). Purchase the Vessel AISPP at FWP regional offices or online, at: https://ols.fwp.mt.gov

  • Motorized watercraft fee is $30. Required for all watercraft that have a motor.
  • Nonmotorized watercraft fee is $10. Required for all nonmotorized watercraft.
  • Proof of purchase can be electronic (cell phone) or paper receipt, there is no decal.
  • The Vessel AISPP expires on December 31.
  • The Vessel AISPP is not transferable between vessels.

Commercially Hauled Watercraft

Requirements for Commercially Hauled Watercraft Entering the State of Montana.  

Commercial haulers transporting watercraft should be aware of Montana’s laws and rules. 

  • Penalties can reach up to a no bond felony. 
  • It is illegal to transport aquatic invasive species, dead or alive, within the state of Montana. Aquatic invasive species can be plants, animals or diseases.  
  • All watercraft being transported in the state of Montana must stop at all open watercraft inspection stations. 
  • It is illegal to transport surface water in the State of Montana. 
  • All aquatic vegetation must be removed from watercraft and trailers prior to transport. 
  • All watercraft must be inspected prior to launch in the State of Montana.

Questions? Call 406-444-2440


Illegal Transportation and Release

It is illegal:

  • To transport AIS into or within Montana.
  • To transport live fish, even baitfish, into Montana. Leeches may be imported if purchased from an approved dealer and accompanied by a receipt.
  • To move live fish, aquatic plants, or invertebrates from one water body to another without FWP authorization.
  • To release live aquarium or bait fish into Montana waters.

It is unlawful to transport surface water.

  • Anglers, where allowed to transport live aquatic bait and bait fish, must use clean non-surface water. 

ENFORCEMENT

  • You can be charged with a felony and fined up to $5000 if you knowingly or purposely attempt to introduce AIS into Montana waters.
  • You can be cited for driving past an inspections station if you are hauling or carrying a watercraft.
  • Different areas of the state have different fishing regulations, especially the transportation of live fish. Do not assume that regulations you follow in eastern Montana apply to central and western Montana. Know the regulations before heading out to fish

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