Round Goby
Round Goby
Neogobius melanostomus
The Round Goby is a freshwater bottom-dwelling fish native to central Eurasia including the Black Sea and Caspian Sea. A type of goby, it is typically 4-10 inches in length and has grey, black, and brown coloring.
While young, its coloring is grey with a distinctive black spot on the front dorsal fin. Upon maturation the coloring becomes spotted with gray, black, brown, and olive green markings. The eyes protrude slightly from the top of the head and it has a suction disk on its pelvic fins.
It feeds nocturnally and is believed to detect prey only while stationary. Its primary diet includes mollusks, crustaceans, worms, fish eggs, small fish, and insect larvae.
Females spawn multiple times during spawning season which spans from April to September. The males guard nest eggs and newly hatched young. Its eggs are 4 by 2.2 mm in size. Female Round Gobys reach maturity in 1-2 years while males do so in 3-4 years.
The species was accidentally introduced into the North American Great Lakes by way of the ballast water of cargo ships. First discovered in the St. Clair River in 1990, the Round Goby is considered an invasive species with significant ecological and economic impact.
An unintended benefit of the introduction is that the Lake Erie Watersnake, an endangered species, has found the Round Goby to be a tasty addition to its diet. A recent study found the Round Goby now accounts for up to 90% of the snake's diet. The new food supply means that the Watersnake is now staging a comeback.
An aggressive fish, the Round Goby feeds off of competitor fish such as the sculpin and longperch, substantially reducing their population size. It also consumes other aquatic resources such as snails and mussels, thereby reducing the availability of food for native species. In areas where the Round goby has become established, the populations of native aquatic life has declined. Its robust ability to survive in degraded environmental conditions has increased its competitive advantage compared to native species.
What effect does the Round Goby have on the other fish and animals of the Great Lakes?
