History shows that achieving the desired effect is difficult. Grass carp introduced to control unwanted aquatic plants in inland lakes resulted in native plant species being decimated. The building of channels, canals and locks creates artificial connections between waterways, allowing the free movement of species across physical barriers. It also facilitates the transport of species by vessels. Commercially-sold live worms and other aquatic organisms for the recreational fishing industry, both the bait species and its packing material, can result in introductions through intentional and unintentional release.
Individuals discard non-native plants in public waterways.
Non-native plants are sometimes accidentally attached to other horticultural species and discarded unintentionally or intentionally. Individuals who do not follow strict protocols for animal management may accidentally release specimens. Accidental release may also occur when those protocols do not exist. Intentional release and escape from confinement are also possible. Ships and boats can introduce organisms through ballast discharge and hull fouling.