I just watched this striking piece on the CBC about an incredibly invasive species, the asian carp. You need to watch until the three-minute mark, when they send a jolt of electricity through the water:
The Army engineer corps has actually built an electric fence between the encroaching fish and Lake Michigan, in the hopes they can keep them out of the Great Lakes. Yeah, like that’ll work. The whole thing reminds me of a particular type of amphibian.
There’s more information on the Asian carp’s trip up the Mississippi on the EPA’s site.