The voracious grass carp is one of four carp species threatening to invade the world’s largest surface freshwater system. The grass carp feeds on aquatic vegetation that provides spawning and crucial habitat while the bighead and silver carp are actually the most feared of the species. They compete with native fish and eat microscopic plants and animals. The Canada-U.S. study Between 2013 and 2016, Fisheries and Oceans Canada’s (DFO) Asian Carp Program recorded and examined 23 grass carps caught in Lake Erie and Lake Ontario. Nine of the fish were fertile grass carp, capable of reproducing. DNA analysis indicated all the fish had been born outside the Great Lakes and made their way into Canada.