"Flathead catfish — native to the Mississippi River basin — were first detected in the Susquehanna River in Pennsylvania in 2002, according to the U.S. Geological Survey. In the two decades since then, the invasive species has spread throughout the river basin. The impact of the large predator on the waterway’s food webs and ecology was unknown, but now a research team is beginning to understand what Susquehanna flatheads are eating and how their presence is affecting native aquatic species in the river.

The findings, which the team said state fisheries managers can use to better manage the waterway, were recently published in Transactions of the American Fisheries Society. The researchers from Penn State, the Pennsylvania Fish and Boat Commission, the U.S. Fish and Wildlife Service, and the U.S. Geological Survey, reported that flatheads are opportunistic feeders preying on dozens of aquatic species. The invaders are voracious and have become the apex predators in the river — some specimens are known to grow more than 4 feet long and nearly 70 pounds in Pennsylvania waters. They have great potential to affect the abundance of riverine fish species, according to the researchers. . ."