Mute swans are territorial, behave aggressively toward other geese and swan populations and produce quantities of waste that foul the water and shorelines. Scientists are studying the Rapa whelk to determine whether its presence could upset the ecosystem. The task of removing exotic species can be extremely costly, running into the millions of dollars. During World War II, the Army Corps of Engineers first conducted a massive effort to remove the water chestnut, an Asian species that spreads in large, dense mats of spiny vegetation that choke creeks and rivers. The water chestnut first appeared in the Bay watershed in the Potomac River in the 1920s.
Vigilance is essential when dealing with exotics.
In 1993, the Chesapeake Executive Council adopted the Policy for the Introduction of Non-Indigenous Aquatic Species . The policy's goal is to minimize the economic or ecological risk associated with first-time introduction of exotic aquatic species to the Bay region. Although regulatory controls currently exist to prevent further introduction of exotics, public education is the best possible method for controlling accidental and intentional introduction.