David A. Fahrenthold updates the status of the local population of northern snakeheads in the Potomac River and its tributary creeks, where the fish is an alien species.
…Snakeheads are thriving. Virginia state scientists who use electric current to stun and capture fish in these creeks used to catch one snakehead every five hours. This year, they got 6.9 fish an hour, nearly 35 times more.
But the snakeheads don’t appear to have had a serious impact on the river’s largemouth or smallmouth bass, which are also top predators in the river. Scientists say they believe this might be because the snakeheads prefer shallower water or different prey.