Round Goby

Daniel Kelly | Fondriest Environmental

A Eurasian native, the Round Goby is believed to have originated from parts of the Black Sea, Caspian Sea and the Sea of Azov. From there, it most likely made its way into U.S. lakes and waterways via ship ballast water. It has proven itself to be an aggressive bottom-dweller with a penchant for expanding into new areas, and inhabits all five of the Great Lakes and many of their tributaries.

The small goby, which only reaches about 6 inches in length, resembles Sculpins, which are a native fish in the Great Lakes basin and have a similar gray color. Round Gobies are distinct from all other non-native fish in the basin, however, because they are the only kind to have a single pelvic fin. This fin is useful because it acts as a suction cup to hold them in place.

Round Goby. (Credit: Center for Great Lakes and Aquatic Sciences Archive, University of Michigan)

Round Gobies are harmful in the Great Lakes and other waterways because of their capability to reproduce quickly. As they can produce offspring six times in just one summer, their populations can increase in a small amount of time. Once established, they eat up food that native fish species need to survive and have a good chance of coming to dominate aquatic habitats. Their reproductive prowess aside, Round Gobies can survive in very poor-quality water, a distinct advantage over other fish.

In addition to their environmental impacts, Round Gobies are a nuisance to fishermen. Many have found that they steal bait off their hooks, eat the eggs of popular game fish and often out-compete with smaller fish looking for food.

Round Gobies can be found in all five of the Great Lakes, as well as tributaries flowing into Illinois, Indiana, Michigan, New York, Ohio, Pennsylvania and Wisconsin:

Distribution map of the Round Goby across the continental United States. (Credit: U.S. Geological Survey)

Prevent Its Spread

Once Round Gobies have established populations in an area, there is little that can be done to eliminate them. Most efforts rely on preventing their spread into new areas, and common steps for doing this include draining water from boats, live wells or bait buckets before use in different waterways; avoiding throwing unwanted bait into the water and instead placing it in the trash; and making sure not to use Round Gobies as bait. Fishermen catching Round Gobies should not release them alive, as it is against many state laws to do so.

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Round Goby

Prevent Its Spread

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