Asian carp threaten to invade the Great Lakes and starve out native fish. What's being done to stop them?

摘要

The Midwest is on alert. An invader species is lurking in the Illinois, Mississippi, and Missouri Rivers. These creatures can grow up to 1.2 meters (4 feet) long, weigh as much as 45 kilograms (100 pounds), and threaten to decimate native fish populations. Even worse: They're moving toward the world's largest freshwater ecosystem—the Great Lakes.