New England's waterways have served as corridors for spreading legally-illegally introduced fish over the past 170 years, resulting in artificially enriched and altered fish assemblages in many lakes and ponds. Biological contamination - in terms of Maine fish introductions, range from the original transplantation of native species (e.g., chain pickerel - 1832) to the early importation of exotic common carp, goldfish, brown trout, and black bass during the latter half of the 19th century and up to the recent illegal introduction of bluegill and green sunfish in the early 21st century. During the 20th century, introduced (transplanted) fish species included such native 'game' species as golden shiner, white perch, chain pickerel, and yellow perch, as well as exotic black crappie, walleye, northern pike, and rudd. Most 'biologically' contaminated (altered) waterbodies occur in the southern portion of the state/region, in direct correlation with the development of suburban and urban centers along major waterways. However, in Maine, there is also the 'top-down effect' of introduced muskellunge from Quebec, Canada within the relatively pristine St. John River drainage. Currently, there are considerable ongoing debates and arguments pertaining to the use and management of introduced sportfish species in Maine. Meanwhile, potentially invasive exotic green sunfish and bluegill are currently moving downstream in the headwaters of the Sebasticook River drainage and may eventually spread throughout the Kennebec River drainage - quite possibly to the detriment of native sunfish species (i.e. pumpkinseed and redbreast sunfish).