One surprise I had during the fracas in the Malheur National Wildlife Refuge in Oregon early this year — a group of armed men led by an anti-government protester took over a federal facility — was the existence of a large-scale plan to eliminate carp from Malheur Lake.

The "five-year plan" was set last year, but the effort to get rid of the fish had started earlier. The common carp was introduced to the lake in the 1920s (or in 1951; depends on who's talking) for its food value. Now "millions" of fish abound in the lake that is eight times larger than Manhattan, so it has been a success.

Then why eliminate them? Because the carp, an "invasive species," changed the character of the shallow body of water from a lake to a marsh, the elimination advocates argued. But is it that simple? Is the ominous, belligerent term "invasive" correct?