The Round Goby is a fish that is native to Eurasia, the Black and Caspian Seas. They tend to inhabit waters that do not have much vegetation, instead they prefer more rocky and gravel habitats. They tend to live close to shore, but have been seen in deeper waters during the winter.  Round Gobies were found in the Great Lakes during the 1990's with the first one in Lake Michigan being found by Professor John Janssen, UW Milwaukee School of Freshwater Sciences, in 1994 in Calumet Harbor.  In the Great Lakes Gobies inhabit a similar place, preferring the rocky places in the shore line.  In the Great Lakes the Round Gobies are an invasive species. They came into the Great Lakes through the ballast of Ocean vessels through the canal system.The Round Goby is classified as an invasive species in the Great Lakes due to being introduced to the new environment.
In both habitats Round Gobies are aggressive, and prey on mussels, eggs, and smaller fish. They spawn in the rocky environment and will aggressively defend their territory from other native species trying to spawn. Round Gobies also have modified mouths that enable them to be able to eat mussels like the invasive Zebra Mussel. Round Gobies are similar to a native fish, they both occupy the same territory and look similar. The Round Goby however is distinguishable from the native Sculpin and Tubenose Goby. The Round Goby can be 4 to 10 inches in length and is grey with blotches of black and brown. They usually have a green tinted dorsal fin and the front dorsal fin usually has a large black spot.
Effects of Round Goby
The Round Goby's diet causes different effects on the Great Lakes ecosystem. As mentioned earlier Round Gobies eat invasive mussels which helps keep the mussels from eating too much plankton and clog water intake systems. Round Gobies however do cause some harm, they eat native fish eggs and take spawning ground away from other fish like the Sulpin. However native wildlife have adapted and started to prey on the Round Gobies, like the Cormorants and some sport fish like the Small Mouth Bass. Round Gobies do carry another risk to the Great Lakes besides stealing breeding grounds. Round Gobies can carry and spread botulism. The infected Gobies that are eaten can spread the poison up the food chain to larger fish and birds.
Long Term Impact
The long term impact of the Round Gobies is not yet known, due to the fact that they are taking care of one invasive species, and have integrated into the food chain of the Great Lakes.
- Patrice Charlebois, J. Ellen Marsden, Kirby Wolfe, David Jude, and Svetlana Rudinka, 1997. The Round Goby (Neogobius melanostomus). A Review of European and North American Literature. Aquatic Ecology Technical Report 96/10. INHS Special Publication No. 20. 1996. 9
- Karl Lydersen. "The Round Goby, an Uninvited Resident of the Great Lakes, Is Doing Some Good." The New York Times, May 26, 2011, A23A.
- Carol A Stepien, and Matthew E. Neilson. "What's in a name? Taxonomy and nomenclature of invasive gobies in the Great Lakes and beyond." Journal of Great Lakes Research 39, no. 4 (2013).
- Lydersen. "The Round Goby", 2011.