Gobies belong to a large family of fish represented by many species throughout the world. Two species from eastern Europe, the round goby and the tubenose goby (Proterorhinus semilunaris) were introduced to the St. Clair River in the late 1980s. It is believed that both species arrived in North America after being transported in the ballast water of ships originating from eastern Europe. In the fall of 2005, the Ontario government amended the Ontario Fishery Regulations to make it illegal to possess round goby and tubenose goby alive.It is also illegal to use them as bait.
 

Characteristics

Both round and tubenose gobies are relatively small fishes that live on the bottom of lakes and rivers. The round goby is the larger of the two species reaching lengths of 25cm (10 in) and lives for up to 5 years. The tubenose goby only reaches a size of 11cm (3 in) and it too lives up to 5 years. They are typically mottled brown in colour, and bear a resemblance to our native sculpins. Unlike the sculpin, gobies have unique pelvic (bottom) fin that is joined underneath the body to form a suctorial disc. It is this disc feature that makes them identifiable from other fish species. This disc enables them to stay on the bottom in fast currents. The round goby also has a prominent black spot on its first dorsal fin.

Round gobies prefer rocky and sandy substrate. They occupy a broad range of depths but are most abundant near shore. Tubenose gobies prefer shallow areas with aquatic vegetation. Where the round goby has been introduced, their populations become very abundant due to its aggressive nature and its ability to spawn several times each season. Both species of gobies feed largely on insects and other small organisms found on the bottom. As round gobies grow larger, they feed heavily on zebra mussels and occasionally on small fish and fish eggs. Unfortunately, it is unlikely that gobies will be successful in controlling zebra mussel numbers.

Distribution

After being discovered in the St. Clair River in 1990, both goby species have been found in Lake St. Clair, the Detroit River, and Western Lake Erie. Round gobies have also been found throughout much of Lake Erie, Lake Huron, Lake Ontario, southern Lake Michigan, and western Lake Superior. It has been found in Michigan's inland waters and recently in inland Ontario, at Trent Severn Waterway (between village of Hastings and Healey Falls), Rice Lake, the Pefferlaw River and Lake Simcoe at the mouth of the Pefferlaw River. The round goby has completed their dispersal throughout the five Great Lakes in less than a decade, a dispersal almost as fast as the zebra mussel. It is believed that the isolated Great Lakes populations on Lake Superior were transported by intralake ship ballast water transfers from the St. Clair River area.

Download the Round Goby distribution map ( PDF File, 384 kb )

Impact

Round gobies have become extremely abundant in the St. Clair River, Lake Erie and parts of Lake Ontario reaching densities of more than 100 per cubic metre of water. In some areas they have become an annoyance to anglers due to their habit of stealing bait. The round goby is an aggressive fish that can spawn several times each season. These characteristics, combined with its abundance and relatively large size, mean that the round goby will probably have an impact on native fish species. The smaller tubenose goby is not as abundant and widespread as the round goby and should not have as much of an impact.

Although it is too early to tell what impact the round goby will have in the Great Lakes, changes have already occurred in the St. Clair River. As round gobies have flourished, the abundance of the small, native, bottom-dwelling fish such as mottled sculpin and native logperch (a small relative of the yellow perch) has declined dramatically in the river. Similar changes are expected to occur where the round goby becomes abundant elsewhere. It is not clear what this will mean for larger fish species, but it could affect their feeding habits. Round gobies have also been observed feeding on the eggs and fry of sportfish and may impact on these populations. Although walleye and other predators are feeding on gobies, their populations have continued to expand despite this predation. Because adult round gobies feed predominantly on zebra mussels, which often have high contaminant levels in their tissues, concerns have been expressed that fish predators may be exposed to higher levels of contaminants by feeding on round gobies. Out-breaks of botulism Type-E (Clostridium botulinum) have been observed to impact round gobies eating infected zebra mussels resulting in die-offs. The out-breaks can go further up the food chain, however, when ducks and/or other fish eat the infected gobies. All of the above impacts are still being researched and studied by several agencies in the Great Lakes region.

Prevention

Although anglers and boaters can help to prevent the spread of gobies to inland waterways, there are no known ways of eliminating gobies from a large open system such as the Great Lakes. Gobies, like many other exotic species are here to stay. Although some predators are feeding on gobies, it is unlikely that they will significantly reduce goby numbers. The proliferation of zebra mussels and quagga mussels in the Great Lakes provides an ample food supply for the round goby, and they will continue to expand their range in the Great Lakes. Early detection of isolated populations may help slow or restrict the spread of round gobies. You can do the following to prevent the spread:

• Learn to identify round gobies and if caught, kill them. Do not throw them back alive 
• Do not use round gobies as baitfish
• Dispose of bait properly: Do not release bait into the water
• Always drain water from your boat, livewell, and bilge before leaving any water access
• Never dip your bait bucket into a lake or river if it contains water from another water source
• Never dump live fish from one body of water into another body of water

Click here to see video on how to prevent the spread of Round Gobies  

Gobies and many other exotic species have been introduced to the Great Lakes through the ballast water of ships. The zebra mussel, spiny water flea, and ruffe were all transported from Europe in this manner. All ships are now required to exchange their ballast water at sea before entering the Great Lakes. Research is also being conducted to find effective ways of treating ballast water to prevent the introduction of harmful exotic species and their movement by ships within the Great Lakes.

Click here for infomration on the Pefferlaw Brook Round Goby Removal Project

If you catch a round goby in an area not shown on the distribution map, preserve the fish in alcohol or freeze it and call the Invading Species Hotline at 1-800-563-7711 or contact your local MNR office.