Round gobies (Neogobius melanostomus) invaded the Great Lakes via ballast water transfer in the early 1990’s. Since that time they have colonized all of the Great Lakes, with significant impacts on benthic fish and invertebrate communities. Recently, researchers documented the migration of these aggressive benthic fish into tributary streams of some of the lakes. Researchers within the GLC are investigating the impact of goby invasion on stream macroinvertebrate communities.
Most identified stream populations of round gobies are composed of relatively small fish compared to lake populations. Since small gobies tend to consume a diverse array of invertebrates, before switching to a diet high in molluscs when older, there is concern they might reduce the prey base for other stream species. Of particular concern is their possible effects on stream-spawning salmonid species since gobies readily consume fish eggs.
The invasive round goby has had clear documented effects on native benthic fishes and recent studies have shown they could have significant effects on recruitment of nest-guarding species like smallmouth bass via egg consumption. Male round gobies locate and defend nests during reproduction, and then guard the eggs laid by females. Native crayfish make use of similar nest cavities during egg incubation, and egg-brooding dates in the two species overlap. These observations set the stage for potential competition for nest cavities between the invasive goby and resident crayfish. GLC researchers are investigating nest cavity competition between the species to understand the possible effects of this fish invader on the benthic community of the Lakes.
