Invasive Species

Invasive species are non-native, introduced species that cause harm to the environment, human health, and/or economy. International trade and travel has increased the rate at which species migrate to new environments where they can have unintended, ill effects. Invasive Species possess certain traits that allow them to out compete and displace native species in their new environment. In the absence of natural predators, an invasive population can grow relatively unchecked and disrupt the native ecosystem until the environment slowly begins to evolve and adapt on its own.



  • Reductions in biodiversity and localized extinctions of native species
  • Losses in ecosystem services such as erosion and flood control
  • Replacement of forage food for native species
  • Direct predation on native species including sport fishes
  • Reductions in dissolved oxygen content in the water, which can lead to fish kills
  • Changes in water clarity
  • Changes in macrophyte abundance


  • Reductions in game fish populations
  • Creation of weed beds impassable to boaters and swimmers
  • Damage to boat engines, steering equipment and other parts
  • Negative aesthetic impacts
  • Sharp shells deter swimmers and divers
  • Fouling of fishing equipment

Human Health:

  • The sap of Giant Hogweed (Heracleum mantegazzianum), in combination with moisture and sunlight, can cause severe skin and eye irritation, painful blistering, permanent scarring and blindness.
  • The sharp shells of Zebra Mussels (Dreissena polymorpha) can potentially cut or scrape swimmers and divers.
  • Feral swine (Sus scrofa) have razor sharp tusks and can be aggressive toward humans and their pets and can carry and transmit several diseases including swine brucellosis, E. coli, trichinosis, and pseudorabies to humans and/or livestock.
  • Feral swine rooting and wallowing habits can disturb water quality in streams, and their resulting waste can foul water supplies.


  • Direct invasive species control and management costs
  • Costs attributed to losses in ecosystem services such as erosion control and fisheries
  • Economic losses to local businesses and tourism relating to impaired uses such as fishing, boating, swimming, navigation, ecological biodiversity, aesthetics, and other recreation uses
  • Annual economic losses due to invasive species in the United States are estimated at over $120 billion per year (Pimental et al 2005)
  • In the Great Lakes region, direct costs attributed to aquatic invasive species accounts for over $100,000,000 a year (Rosaen et al, 2012).

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Prevention is the most cost effective management strategy for the control of invasive species. Increasing awareness levels of invasive species issues and educating the public on prevention best management practices are key. Once a species is established in an ecosystem, direct costs associated with management and indirect economic losses can spiral out of control. 100_6028.JPG

Best Management Practices for Invasive Species Prevention

  • Clean, drain, and dry all boating, angling, and recreational gear before moving between waterways.
  • Never transport uncertified baitfish between waters.
  • Always dispose of unwanted bait in the trash, not the ground.
  • Never release unwanted species from home aquariums. 
  • Never release live seafood into the wild.

Conesus Lake Watershed Council Invasive Species Prevention and Response Plan

The Conesus Lake Watershed Council approved an Invasive Species Prevention and Response Plan in 2013. The plan identifies pathways for invasive species introduction and associated prevention projects, outlines a monitoring program, and prescribes a detailed response protocol in the event of a confirmed sighting.

To report a suspect invasive species sighting, please contact the Conesus Lake Watershed Manager at (585) 243-7550.