Round gobies are bottom-dwelling fish in the family Gobiidae. They are native to central Eurasia including the Black and Caspian Seas and arrived in the Great Lakes region via the ballast water of large, oceanic cargo ships. Gobies were first introduced in the St. Clair River in 1990 and had since been confirmed to be present in all 5 of the Great Lakes.
Since their introduction in the Great Lakes, Gobies have caused significant economic and ecological harm. They have the capability to spawn multiple times a year allowing them to grow large populations. They out-compete native bottom-dwelling fish, such as sculpins, darters, and important sport fish, such as smallmouth bass and walleye, for food, habitat and spawning areas. They also feed on the eggs and fry of lake trout and other economically significant fish and affect recreational fishing due to their tendency to steal bait from hooks. Furthermore, round gobies have the potential to transfer contaminants to sport fish which could increase health concerns regarding the consumption of fish. This concern exists due to their tendency to eat large quantities of zebra mussels, which as filter feeders consume toxins. Although laboratory studies in North America have shown that a single goby can consume up to 78 zebra mussels a day, it is unlikely that gobies alone will have a detectable impact on zebra mussel populations.
Gobies are found in both fresh and saltwater ecosystems. They are benthic dwellers spending their lives on the bottom of lakes and oceans. There have been confirmed round goby sightings in all of the Great Lakes.
Body: Round gobies are small, soft-bodied fish that have a distinctive black spot on their first dorsal fin. They have a pelvic fin that is fused to form a single disc on the belly that is shaped like a suction cup. They have puffy cheeks and large eyes that protrude slightly from the top of their heads.
Color: upon maturation, round gobies become mottled with gray, black, brown and olive green markings. During spawning season male gobies turn an inky black color and develop swollen cheeks.
Length: Round gobies range from 4-10 inches in length with a maximum length of 9.7 inches.
Weight: they weigh between 1-2 ounces that fluctuate as they mature.
Males are larger than females, and can be differentiated more so from females by their urogenital papilla (external genitalia) which is white to grey colored and pointed in males. males turn black and form puffy cheeks during mating season.
Females are smaller than males and can be differentiated from males by their urogenital papilla (external genitalia) which is brown in color, short and blunt-tipped.
Juvenile gobies less than 1-year-old are grey in color.
Control methods for round goby include the use of electrical barriers and chemical piscicides to deter movement.
What you can do:
Learn to identify round gobies and educate yourself on their impacts. Never empty bait buckets into a different body of water from where you obtained it. Dispose of unused bait in the trash instead of in the water. If you find a round goby in waters that are different from what they are already known to be, contact your state Department of Natural Resources.
Title photo: (lakescientist.com). Habitat/Distribution map: (Protectyourwaters.net). Goby diagram: Donna Francis, (dnr.wi.gov). Close up of goby face: U.S. Fish and Wildlife Service Archive (bugwood.org). Black colored male goby: NY DEC, (bugwood.org). Don’t dump bait logo: (www.protectyourwaters,net).
“Harmful Aquatic Hitchhikers: Fish: Round Goby.” Harmful Aquatic Hitchhikers: Fish: Round Goby. Stop Aquatic Hitchhikers, n.d. Web. 30 July 2015. <http://www.protectyourwaters.net/hitchhikers/fish_round_goby.php>.
“Round Goby.” Round Goby. Aquatic Nuisance Task Force, n.d. Web. 30 July 2015. <http://www.anstaskforce.gov/spoc/round_goby.php>.
“Round Goby.” Wikipedia. Wikimedia Foundation, n.d. Web. 30 July 2015. <https://en.wikipedia.org/wiki/Round_goby>.
“Round Goby Neogobius Melanostomus.” Invasives.org. Center for Invasive Species and Ecosystem Health, n.d. Web. 30 July 2015. <http://www.invasive.org/browse/subinfo.cfm?sub=12252>.