The round goby first appeared in Lake Superior's Duluth/Superior harbor in 1995 and there is a drastic invasion of the fish into many Great Lakes tributaries, including several areas of the Thames, Sydenham, Ausable and Grand Rivers. It is an intruder to Canadian waters and originates from the Black and Caspian Seas. The most likely cause of origin is that the fish arrived in the ballast water of ocean going ships.
This invasion poses many potential threats for native species of fish and mussels. The goby is capable of rapid population growth. Spawning repeatedly during the summer, a female can produce up to 5,000 eggs. Most surprising is that the diet of the goby not only includes fish eggs and insects, but also zebra mussels.
The Ontario Ministry of Natural Resources advises anglers to be watchful for round goby and if they catch one, do not release it back into the water. Other tips to prevent the spread of round goby include not releasing live bait into the water, draining your boat before leaving any water access and never transferring fish from one location to another.
If people do catch round goby they should report the capture to http://www.invadingspecies.com.