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Aquatic Invasive Species Resources

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Zebra Mussels

Watch short video on cut feet from zebra mussel shells. 
This was videotaped with home camera on Pelican Lake, MN.

What is a zebra mussel?

  • A zebra mussel is a small freshwater mollusk.
  • Zebra mussels get their name from the striped pattern of their shells, though not all shells bear this pattern. They're usually about fingernail size but can grow to a maximum length of nearly 2 inches.
  • A female zebra mussel begins to reproduce at 2 years of age, and produces between 30,000 and 1 million eggs per year.

What is the issue?

  • Zebra mussels are filter feeders. An adult zebra mussel filters up to a quart of water per day, which multiplied by millions of mussels means that the mussels may be filtering all the water in a lake or stream in a day. The animals and algae that are the food of zebra mussels are also the food for larval fish and other native species, so a large zebra mussel population may cause a decline in other animals, including native fish, mollusks, and birds.
  • The filter-feeding activity of zebra mussels causes a related and frequently dramatic increase in water clarity in infested lakes and rivers which can accentuate aquatic plant growth.

Why should I care?

  • Zebra mussels can severely affect native mussels and clams by interfering with their feeding, growth, movement, respiration, and reproduction. For example, zebra mussels can colonize a clam shell to such an extent that the clam cannot open its shell to eat. Some native mussels have been found with more than 10,000 zebra mussels attached to them. In addition to colonizing native mussels and clams, zebra mussels may attach to slow-moving species such as crayfish and turtles.
  • In addition to the impact on wildlife, zebra mussels cause many problems for people. They may colonize water intake pipes, severely restricting the water flow to power plants or other municipal or private facilities that rely on fresh water. Impacts include damage to the facilities as well as the cost of removing or controlling the mussels. Zebra mussel shells may also foul beaches and near-shore swimming areas.  Bare feet are at risk from the sharp shells, and clean up costs are high.   Due to changes in fish populations, zebra mussels also adversely impact recreational fishing.

What can I do?

  • Clean off plants, animals and mud from your boat, personal watercraft, and recreation gear.
  • Drain your boat, livewell, ballast tanks, and bait containers and leave plugs out while traveling.
  • Rinse boat, livewell and gear with hot water at 140 degrees, spray with high-pressure, or dry for at least 5 days. 
  • Replace water in bait containers with tap water.

Flowering Rush

What is flowering rush?

  • Flowering rush is an aquatic plant that can grow as an emergent plant along shorelines and as a submersed plant in lakes and rivers.

What is the issue?

  • Flowering Rush can form dense stands which crowds out native plants, harms fish and wildlife and interferes with recreational lake use. 

Why should I care?

  • Dense stands of flowering rush interfere with swimming, boating and other use of lakes.

What can I do?

  • Remove all plant fragments from your boat, trailer, and propeller prior to leaving the launch site. The transportation of plant fragments is the main introduction route to new lakes and rivers.
  • Rinse any mud and/or debris from equipment and wading gear and drain any water from boats before leaving the launch area.
  • Get active with local initiatives to control or manage flowering rush in your community.

Eurasian Watermilfoil

What is Eurasion watermilfoil?

  • Eurasian watermilfoil is an invasive, underwater aquatic plant

What is the issue?

  • Eurasian watermilfoil is an aggressive, rapidly growing plant that overruns native plants and clogs waterways.  When mature, the plant forms an extremely dense surface canopy that inhibits boating, fishing and swimming activities.  It causes nuisance algae blooms and the water to become stagnant. 

Why should I care?

  • Eurasian watermilfoil can disrupt the ecology of a water body by crowding out important native aquatic plants needed for a healthy fishery. It can potentially reduce property values. Under severe conditions, property owners and lake associations can expect increased costs to keep boat channels open by mechanical harvesting and for costs associated with disposal of rotting vegetation.
  • In shallow areas the plant can interfere with water recreation such as boating, fishing, and swimming.
  • The plant can clog boat motors causing damage.
  • Can cause a significant increase in permanent pool mosquitoes. 
  • Reduced levels of dissolved oxygen enables nutrients to accumulate, creating possible unfavorable conditions for macroinvertibrates and fish. 

What can I do?

  • Clean boat propeller and trailer of weeds before leaving area. 
  • Get involved in local efforts.
  • INSPECT and REMOVE all aquatic plants and animals
  • DRAIN water from motors, live wells and bait containers
  • DISPOSE of unwanted live bait on land
  • RINSE your boat and equipment with hot (140°F) high pressure tap water or
  • DRY your boat and equipment for at least 5 days
  • Detecting infestations early and report to the Minnesota Department of Natural Resources.
  • Know if Eurasian watermilfoil is in lakes you visit. 

Spiny Waterflea

What is a Spiny waterflea?

  • Spiny waterfleas are zooplankton (microscopic animals).
  • Adults range from 1/4 to 5/8 inch long. A spiny waterflea has a single long tail with small spines along its length.

What is the issue?

  • Spiny waterfleas eat small animals (zooplankton), including Daphnia, which are an important food for native fishes. In some lakes, they caused the decline or elimination of some species of native zooplankton. They can clog eyelets of fishing rods and prevent fish from being landed.
  • They can spread by attaching to fishing lines, downriggers, anchor ropes, and fishing nets. While female waterfleas die out of water, under certain conditions they produce eggs that resist drying and freezing, and can establish a new infestation. They also can be unintentionally transported in bilge water, bait buckets, or livewells.
  • Spiny waterfleas collect in gelatinous globs on fishing lines and downrigger cables. They prefer deep lakes, but can be found in shallow lakes and rivers.

Why should I care?

  • The spiny water flea has become a serious concern for fishermen and affects the economies of local communities where fishing is a tourism draw.  Spiny water fleas collect in masses on fishing lines and can clog the first eyelet of rods, damage a reel’s drag system, and prevent fish from being landed. 
  • Spiny waterfleas can impact tourism in areas when fishermen don’t come to recreate.

What can I do?

  • Learn to recognize them.
  • Inspect and remove gelatinous material from fishing lines.
  • Drain water before transporting boats, personal watercraft, and bait containers.
  • Report new infestations to the Minnesota Department of Natural Resources.


Natural Innovations, 17561 Otto Zeck Road, Detroit Lakes, MN 56501