Tracking Missouri's Exotics

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Published on: Jan. 2, 2000

Last revision: Nov. 4, 2010

The word "exotic" brings to mind something unique, rare and beautiful, but in essence the word primarily refers to something that has come from another place, that is not native. Organisms that have been moved into areas where they did not naturally live are called exotic or introduced species.

Scientists estimate that over the past 100 years close to 4,500 plants and animals have been introduced into North America. Exotic species have been introduced intentionally by natural resource managers to enhance hunting and fishing opportunities or to control other organisms. For example, many of us feel we have benefited from the introduction of pheasants from China and brown trout from Europe.

Introduced species have become a national concern because they can cause problems for native species. Exotic plants or animals can disrupt the harmony of an environment, even completely changing the habitat and displacing the species that originally lived there. Introduced species have been cited as the second leading cause in the extinction of North American freshwater fishes, following habitat destruction and ahead of pollution. In response to the damage caused, President Clinton recently issued an executive order to encourage action to control invasive and introduced species.

Scientists believe introduced species may play a major role in the decline of native fish and other aquatic organisms. The negative effects of introduced species are not always immediately apparent and may be difficult to separate from the problems caused by declining habitat and pollution. Sometimes we don't recognize a problem until an exotic plant or animal has already established itself and driven out other species.

Exotics plants and animals sometimes are introduced intentionally into ponds, lakes or streams in Missouri to increase recreation, to provide food for other fish and to control vegetation.

Sometimes these introductions go awry. Take the common carp, for example. It was intentionally introduced in the U.S. in 1876. At the time, carp were a popular sportfish in Europe. Stocking was stopped by 1895, but the carp had already established itself in Missouri waters. Now they are the most common large fish in the state.

To get an idea of their effect, imagine that each pound of carp takes up the space and resources that might be used by a pound of game fish. Although carp feed a commercial fishing industry in Missouri and elsewhere, the aggressive fish uproot plants, muddy the water and eat the eggs of other fish, adversely impacting native species and

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