What are nonindigenous aquatic species?
We define nonindigenous aquatic species as a member(s) (i.e. individual, group,
or population) of a species that enters a body of water or aquatic ecosystem
outside of its historic or native range.
Most of the nonindigenous introductions are a result of human activities since
the European colonization of North America. This includes not only species that
arrived from outside of North America, which are commonly referred to as exotics,
but also species native to North America that have been introduced to drainages
outside their native ranges within the country. An example of the former
would be the Brown Trout, Salmo trutta, a native of Europe first imported
to the United States in 1883 from Germany. An example of the latter would be
the Coho Salmon, Oncorhynchus kisutch, a native to the Pacific coast
from northern California to Alaska, which was introduced into the Great Lakes
as early as the 1920's.
The importance of studying nonindigenous organisms is to learn what effects
they may have on the native organisms and the physical environment.