Since the round goby arrived in the Great Lakes more than a decade ago, the small but feisty fish has spread rapidly and has caused local extinctions of a native species. Researchers now have identified just how the gobies take over.
In those places where the pencil-length bottom-dwellers have proliferated, populations of the mottled sculpin, an important prey species for larger fish, have crashed. In a soon-to-be-published study, lake researchers show that the gobies win turf by appropriating sculpins' nesting sites. With its ability to spawn diminished, the days of this indigenous population are numbered, the researchers say.