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Resources | Invasive Species
Round Goby
The round goby (Neogobius melanstomus) is a small, bottom— dwelling fish that was first found in the Great Lakes region in 1990. Originally from the Black and Caspian Sea areas of Eastern Europe, it is believed that this exotic species arrived in the ballast water of vessels coming into the Great Lakes. Since the first sighting in the St. Clair River, round gobies have spread to all of the Great Lakes and are working their way inland through the rivers and canal systems.
Characteristics
Gobies are relatively small (about 25 cm) bottom dwelling fishes. They prefer rocky and sandy lake bottoms and can occupy a broad range of depths, but are the most abundant in the nearshore.
Their populations have exploded in the Great Lakes because of their aggressive nature, and their ability to spawn several times per season. The fish feeds on insects and other small organisms found on the lake bottom. They also feed heavily on Zebra Mussels and occasionally on small fish and fish eggs.
Gobies link to Bird and Fish Die-offs
Field investigations have suggested that the die-offs observed in Lake Huron may be the result of botulism type E poisoning. Toxins from the bacterium Clostridium botulinum and specifically Type E botulism, which is found in fish-eating birds in the Great Lakes, cause these die-offs. The botulism toxin is produced in the absence of oxygen and with suitable temperature and nutrient conditions. It remains unclear which factors trigger the bacterium to produce the neurotoxin and the ensuing fish and wildlife die-offs.
Species commonly found during die-off events include: Freshwater Drum (Sheepshead), Smallmouth Bass, Rock Bass, Round Gobies, and Channel Catfish. Bird species include Loons, Cormorants, Mergansers, Gulls and other waterbirds. It is suspected that zebra and quagga mussels are ingesting the botulinum bacteria (invertebrates are not affected by botulism).
Round gobies are known to heavily feed on mussels; therefore, they are thought to be ingesting the bacteria. Native fish species such as those commonly associated with the die-off are starting to feed primarily on the round goby; thus, they become affected by botulism. This movement of botulism is believed to be leading to the fish die-offs commonly.